JP6609124B2 - Engine valve and manufacturing method thereof - Google Patents

Description

The present invention relates to an engine valve and a manufacturing method thereof.

In vehicles such as automobiles equipped with an engine, a large amount of heat is generated in the engine part, but the generated heat is easily diffused to the surroundings through the engine member, and the generated heat is not necessarily fully utilized. It is.

Therefore, researches have been actively conducted to effectively use the heat generated in the engine and improve characteristics such as fuel efficiency, and attempts have been made to insulate engine valves in order to reduce heat loss. It has been broken.

Patent Document 1 discloses a technique for heat insulation of an engine valve, in which a film is formed by spraying ceramics or an alloy on the umbrella front and back of the valve. Patent Document 2 discloses a paint for exhaust system parts that is a technique for achieving heat insulation and is applied to a base material made of metal.

JP 2003-307105 A International Publication No. 2014/034395

However, in Patent Document 1, since the coating is formed by thermal spraying, the adhesion between the metal engine valve and the coating cannot be said to be sufficient. During engine operation, engine valves are subject to significant thermal and physical shocks. Under the harsh environment in which such an engine valve is used, the technique of Patent Document 1 has a problem that the film peels from the engine valve.

When a coating film is formed on a base material made of metal using the paint for exhaust system parts of Patent Document 2, since the glass component is baked on the base material made of metal, the metal component and the glass component are chemically bonded to each other. Good adhesion can be ensured. However, the technique of Patent Document 2 has a problem that the paint contracts when the paint containing the glass component is baked to form a film. This is a phenomenon caused by the difference in thermal expansion coefficient between the metal and the paint, and this shrinkage phenomenon becomes significant when the film thickness is large. Due to this contraction, there is a problem that the end of the formed film is drawn (retracted) toward the center of the film, and the thickness of the film is reduced at the end. Therefore, even if the above-mentioned film is formed on the side surface of the umbrella part of the engine valve for the purpose of enhancing the heat insulation, for example, the end of the film on the umbrella hem side is pulled toward the shaft part side, and the film on the end part is It will be thinner. Thus, if there is a thin portion in the film, the heat insulating performance of the portion is inferior, and therefore sufficient heat insulating performance cannot be exhibited.

The present invention has been made in view of the above-described problems, and provides an engine valve that has high heat insulating properties and that makes it difficult for a glass coat layer formed on the back of an engine valve umbrella to peel off from a metal substrate. With the goal.

In order to achieve the above object, the engine valve of the present invention is an engine valve composed of an umbrella part and a shaft part, and is a metal base material constituting the engine valve and a side surface of the umbrella part of the metal base material. The glass coat layer is formed in a portion other than the umbrella skirt on the back of the umbrella, and a part of the glass coat layer is exposed, and the end of the glass coat layer on the umbrella skirt side is formed on a part of the surface of the glass coat layer. It consists of a ceramic member arranged so as to cover.

The umbrella back surface of the engine valve of the present invention includes an umbrella skirt portion where the glass coat layer is not formed and a portion other than the umbrella skirt portion where the glass coat layer is formed. In the present specification, the “umbrella back surface” refers to the side surface of the umbrella portion. When the engine valve of the present invention is used in an engine, the rear surface of the umbrella is the surface of the engine valve that does not face the engine combustion chamber when the engine valve is closed. The engine valve umbrella surface is the surface of the engine valve umbrella that faces the engine combustion chamber when the engine valve is closed.
The umbrella skirt portion on the back surface of the umbrella is a predetermined region from the umbrella skirt on the back surface of the umbrella toward the shaft portion. The umbrella hem is the end of the umbrella back side on the umbrella surface side.
The portion other than the umbrella skirt portion on the back surface of the umbrella is the umbrella back surface from the shaft portion side end portion of the umbrella skirt portion to the shaft portion of the engine valve.

When the engine valve of the present invention is used in an engine, the umbrella skirt portion where the glass coat layer is not formed becomes a portion in contact with the cylinder.
In the present invention, since the glass coat layer is formed on the portion other than the umbrella skirt portion on the back side of the umbrella of the engine valve, the heat insulation of the engine valve can be enhanced.

The engine valve of the present invention is fired to form a glass coat layer by arranging a ceramic member so as to cover an end of the glass coat layer formed on the metal substrate on the umbrella skirt side. In the process, even if the glass coat layer (glass paste layer) adjacent to the umbrella skirt portion tends to shrink in the axial direction of the engine valve, the shrinkage is inhibited by the weight of the ceramic member. For this reason, even if it passes through the sintering process for forming a glass coat layer at the time of manufacture, the edge part by the side of the umbrella bottom of a glass coat layer does not generate | occur | produce in the umbrella back surface. For this reason, the problem that the thickness of the glass coat layer on the back surface of the umbrella becomes thin at the end on the umbrella skirt portion side does not occur, and as a result, high thermal insulation performance can be exhibited.

Further, in the engine valve of the present invention, when the glass coat layer is formed by sintering, strong adhesion is developed between the metal substrate and the glass coat layer and between the glass coat layer and the ceramic member. For this reason, even in a harsh environment where the engine valve is used, the glass coat layer formed on the back surface of the umbrella of the engine valve is difficult to peel off from the metal base material, and high heat insulation performance can be exhibited.

Furthermore, in the engine valve of the present invention, since the glass coat layer is partially exposed on the surface (the glass coat layer is not covered with the ceramic member), the ceramic member and the glass coat layer are The bonded part is the minimum area necessary for these close contact. As a result, the stress due to the difference in thermal expansion coefficient between the ceramic member and the glass coat layer can be alleviated as much as possible, and even if the toughness of the glass coat layer is low, the glass coat layer breaks in the sintering process. Damage is prevented.

The engine valve of the present invention has high heat insulation. Therefore, the following effects are exhibited.
When the engine valve of the present invention is used for an engine, the engine valve of the present invention can be used as both an intake side engine valve and an exhaust side engine valve.
When the engine valve of the present invention is used as an engine valve on the intake side, the engine valve of the present invention has high heat insulation, so that the heat of the engine valve is not easily transmitted to the intake air. Therefore, the engine can be operated without reducing the intake efficiency.
Further, when the engine valve of the present invention is used as an engine valve on the exhaust side, the engine valve of the present invention has high heat insulation properties, so that the heat of the exhaust is not easily transmitted to the engine valve. Therefore, the temperature of the exhaust gas is unlikely to decrease. Exhaust gas from the engine is purified by a carrier installed in an exhaust gas purification device installed downstream of the engine. If the temperature of the exhaust gas is not lowered, the exhaust gas quickly raises the temperature of the carrier. The exhaust gas purification function of the carrier can be suitably exhibited. That is, when the engine valve of the present invention is used as an engine valve on the exhaust side, exhaust gas purification efficiency is improved.

In the engine valve of the present invention, the ceramic member preferably has pores.
When the ceramic member has pores, the heat insulating performance of the engine valve is further improved. Moreover, even if a stress due to a difference in thermal expansion occurs between the glass coat layer and the ceramic member in the sintering step when forming the glass coat layer, the stress is relieved by the pores. For this reason, even when the toughness of the glass coat layer is low, the glass coat layer is prevented from being broken and broken during sintering.
Moreover, it is preferable that the component of the glass coat layer has penetrated into the pores of the ceramic member. In the sintering process, the glass coat layer raw material diffuses into the pores and exhibits an anchor effect, whereby stronger adhesion between the glass coat layer and the ceramic member is possible.

In the engine valve of the present invention, the glass coat layer preferably has pores.
When the glass coat layer has pores, the heat insulating performance of the engine valve is further improved. Moreover, even if a stress due to a difference in thermal expansion occurs between the glass coat layer and the ceramic member in the sintering step when forming the glass coat layer, the stress is relieved by the pores. For this reason, even if the toughness of the glass coat layer is low, the glass coat layer is prevented from being broken and broken in the sintering process.

In the engine valve of the present invention, the glass coat layer preferably has a thickness of 1 to 1000 μm.
If the thickness of the glass coat layer is less than 1 μm, the heat insulation of the engine valve may not be sufficiently improved. If the thickness of the glass coat layer exceeds 1000 μm, cracks may easily occur when a thermal shock or the like is applied to the glass coat layer.

In the engine valve of the present invention, the width of the umbrella skirt is preferably 3 to 20% of the width of the umbrella back in the direction from the umbrella skirt on the back of the umbrella toward the shaft of the engine valve.
When the width of the umbrella bottom surface is within the above range, when the engine valve of the present invention is used in an engine, the portion of the engine valve that comes into contact with the cylinder can be made sufficiently large. It is possible to prevent the engine valve from being broken by an impact caused by repeated collisions. Moreover, since the ratio of the umbrella back surface covered with the glass coat layer can be sufficiently increased, a sufficient heat insulating effect can be obtained.

When the width of the umbrella hem is less than 3% of the width of the back of the umbrella, when the engine valve of the present invention is used in an engine, the portion of the engine valve that comes into contact with the cylinder becomes small. Will repeatedly impact, so the impact per unit area on the umbrella skirt will be stronger, and the engine valve will be easily broken. On the other hand, when the width of the umbrella skirt exceeds 20% of the width of the umbrella back surface, the ratio of the umbrella back surface covered with the glass coat layer decreases, and it becomes difficult to obtain a sufficient heat insulating effect.
In this specification, “the direction from the umbrella hem on the back of the umbrella toward the shaft portion of the engine valve” means the direction of a straight line connecting the point from the umbrella hem to the shaft portion so as to be the shortest distance. To do.

Moreover, it is preferable that the area of the umbrella skirt part in the back of the umbrella is 5 to 50% of the area of the back of the umbrella.
When the area of the umbrella skirt is less than 5% of the area of the back of the umbrella, when the engine valve of the present invention is used in an engine, the portion of the engine valve that contacts the cylinder becomes small. Since the engine valve and the cylinder repeatedly collide, when the umbrella skirt becomes small, the impact per unit area at the umbrella skirt becomes strong. Therefore, if the area of the umbrella skirt is less than 5% of the area of the back of the umbrella, the engine valve is likely to be broken.
When the area of the umbrella skirt exceeds 50% of the area of the umbrella back surface, the ratio of the umbrella back surface covered with the glass coat layer decreases. Therefore, it becomes difficult to obtain a sufficient heat insulating effect.

The glass coat layer is preferably made of an amorphous inorganic material and a crystalline inorganic material.
The amorphous inorganic material functions as a glass layer covering the engine valve. Further, the crystalline inorganic material plays a role as a member for improving heat resistance. Further, the presence of the amorphous inorganic material and the crystalline inorganic material in the glass coat layer increases the strength of the glass coat layer.

In the engine valve of the present invention, the amorphous inorganic material is preferably a low softening point glass having a softening point of 300 to 1000 ° C.
When the amorphous inorganic material is the above-mentioned low softening point glass, the amorphous inorganic material is softened and melted by heating at a temperature exceeding the softening point and spreads on the surface of the engine valve to become a glass coat layer.

In the engine valve of the present invention, the crystalline inorganic material is preferably made of at least one selected from the group consisting of alumina, zirconia, yttria, calcia, magnesia, ceria and hafnia.
The glass coat layer containing the crystalline inorganic material having excellent heat resistance performance is improved in heat resistance. Also, the heat insulation performance is improved.

In the engine valve of the present invention, the ceramic member is preferably made of zirconia.
A ceramic member made of zirconia is preferable because of its excellent heat resistance. Zirconia is preferable because of its good adhesion to the glass coat layer.

In the engine valve of the present invention, the ceramic member has a ring shape, and a concave portion is formed in a portion adjacent to the umbrella skirt portion on the back surface of the umbrella, and the end portion of the glass coat layer enters the concave portion. The ring-shaped ceramic member is preferably fitted into a recess in which the glass coat layer is formed.
When the engine valve of the present invention is configured as described above, the metal base material expands larger than the ceramic member during firing to form the glass coat layer, and is strong when the temperature is returned to room temperature. A so-called “shrink fit” occurs in a fitted state, and the adhesion of the ceramic member to the metal substrate is improved.
The cross-sectional shape of the recess is preferably an arc shape or a right-angled V shape.

The method for manufacturing the engine valve of the present invention includes:
A method of manufacturing the engine valve,
A step of forming a glass paste layer by applying a glass paste to a portion other than the umbrella hem portion on the back surface of the umbrella, which is a side surface of the umbrella portion of the metal base composed of the shaft portion and the umbrella portion;
A step of disposing a ceramic member on a part of the surface of the glass paste layer so as to cover an end of the glass paste layer on the umbrella skirt side; and
A step of forming the glass coat layer by sintering the glass paste layer and bonding the ceramic member and the metal base material via the glass coat layer are included.

In the manufacturing method of the present invention, the glass coating layer is formed by disposing the ceramic member so as to cover the end portion of the glass paste layer applied to the portion other than the umbrella hem portion on the back surface of the umbrella of the metal base material. Even after the sintering for forming the film, the end of the glass coat layer on the umbrella skirt portion side does not shrink on the back surface of the umbrella. For this reason, the problem that the thickness of the glass coat layer on the back surface of the umbrella becomes thin at the end on the umbrella skirt portion side does not occur, and as a result, an engine valve that can exhibit high heat insulation performance can be manufactured.

In the manufacturing method of the present invention, since the ceramic member is disposed on a part of the surface of the glass paste layer, a part of the glass paste layer is exposed on the surface. For this reason, the part where the glass coat layer formed from the glass paste layer and the ceramic member are in contact with each other is the minimum area necessary for the adhesion. As a result, the stress due to the difference in thermal expansion coefficient between the ceramic member and the glass coat layer can be alleviated as much as possible, and even if the toughness of the glass coat layer is low, the glass coat layer breaks in the sintering process. Damage is prevented.

Furthermore, in the manufacture of the engine valve, a ceramic member is disposed on the glass paste layer, and then the glass paste layer is sintered, so that the gap between the metal substrate and the glass coat layer and between the glass coat layer and the ceramic member is reduced. Strong adhesion is developed between them. For this reason, according to the method for manufacturing an engine valve of the present invention, it is possible to manufacture an engine valve that has high heat insulating properties and the glass coat layer formed on the back of the engine valve is difficult to peel from the metal substrate.

The ceramic member used for the engine valve is the engine valve of the present invention.
For this reason, the engine valve using the ceramic member can exhibit high heat insulation performance.

Fig.1 (a) is a perspective view which shows an example of the engine valve of this invention, FIG.1 (b) is the sectional view on the AA line of the engine valve shown to Fig.1 (a). Fig.2 (a) is a perspective view which shows another example of the engine valve of this invention, FIG.2 (b) is a BB sectional drawing of the engine valve shown to Fig.2 (a). FIG. 3 is a longitudinal sectional view showing still another example of the engine valve of the present invention. FIG. 4 is a longitudinal sectional view showing still another example of the engine valve of the present invention. FIG. 5 is a longitudinal sectional view showing still another example of the engine valve of the present invention. FIG. 6 is a cross-sectional view schematically showing an example of the structure of an engine combustion chamber in which the engine valve of the present invention is used. It is sectional drawing which expanded further the AA sectional view taken on the line in FIG.1 (b). FIG. 8 is a schematic cross-sectional view of a sample for coating layer strength measurement. FIG. 9 is an external view of a tensile test by a tensile tester.

Hereinafter, the engine valve of the present invention will be described in detail.

Detailed Description of the Invention
The engine valve of the present invention is
An engine valve consisting of an umbrella part and a shaft part,
A metal base material constituting the engine valve, a glass coat layer formed on a portion other than an umbrella skirt on the back of the umbrella, which is a side surface of the umbrella part of the metal base material, and a part of the surface of the glass coat layer And a ceramic member arranged so as to cover the end of the glass coat layer on the umbrella skirt side.

Examples of the engine valve of the present invention include the following configurations.
That is, the engine valve which is an example of the engine valve of the present invention includes a rod-shaped shaft portion and a substantially conical umbrella portion, and the shaft portion includes a metal substrate. On the other hand, in the umbrella portion, a glass coat layer is formed on a portion other than the umbrella skirt portion on the back surface of the umbrella, which is the side surface of the umbrella portion of the metal base material. Moreover, the recessed part (counterbore part) is formed by the cutting process in the part adjacent to the umbrella skirt part of an umbrella back surface, and the edge part of the glass coat layer has entered the inside of a recessed part. A ceramic member having a substantially right-angled cross-section and a ring-shaped three-dimensional shape is accommodated in the recess and arranged to cover the end of the glass coat layer on the umbrella skirt side. And the ceramic member are bonded to each other.

In the engine valve having the above configuration, a concave portion is formed on the umbrella back surface of the umbrella portion, and an end portion of the glass coat layer enters the inside of the concave portion. The ceramic member is accommodated in the recess and is disposed so as to cover the end of the glass coat layer on the umbrella skirt portion side, and the end of the glass coat layer and the ceramic member are bonded. For this reason, even if the glass paste layer for forming the glass coat layer adjacent to the umbrella skirt portion in the firing process tries to shrink in the axial direction of the engine valve, the shrinkage is hindered by the weight of the ceramic member, and the glass coat layer is manufactured at the time of manufacture. Even after the sintering step for forming the layer, the end of the glass coat layer on the umbrella skirt side does not shrink on the back of the umbrella.

The shape and structure of the above-described engine valve of the present invention will be further described in detail.
Fig.1 (a) is a perspective view which shows an example of the engine valve of this invention, FIG.1 (b) is the sectional view on the AA line of the engine valve shown to Fig.1 (a).

As shown in FIGS. 1A and 1B, an engine valve 10 which is an example of the engine valve of the present invention includes a rod-shaped shaft portion 11 and a substantially conical umbrella portion 12, and the shaft portion 11 is It consists of a metal substrate. On the other hand, in the umbrella part 12, the glass coat layer 13 is formed in parts other than the umbrella skirt part 220 of the umbrella back surface 22a which is the side surface of the umbrella part 22 of a metal base material. Moreover, the recessed part (counterbore part) 220a is formed by the cutting process in the part adjacent to the umbrella skirt part 220 of the umbrella back surface 22a, and the edge part of the glass coat layer 13 has entered the inside of the recessed part 220a. . And the ceramic member 15 whose cross section is a substantially right triangle (refer FIG.1 (b)) and whose three-dimensional shape is a ring shape is accommodated in the recessed part 220a, and the edge part by the side of the umbrella skirt part 220 side of the glass coat layer 13 The edge part of the glass coat layer 13 and the ceramic member 15 are adhere | attached.

In the engine valve 10 shown in FIGS. 1 (a) and 1 (b), a concave portion 220a is formed on the umbrella back surface 22a of the umbrella portion 22, and the end portion of the glass coat layer 13 enters the inside of the concave portion 220a. Yes. The ceramic member 15 is accommodated in the recess 220a and is disposed so as to cover the end of the glass coat layer 13 on the umbrella skirt 220 side, and the end of the glass coat layer 13 and the ceramic member 15 are bonded to each other. . For this reason, even if the glass paste layer for forming the glass coat layer 13 adjacent to the umbrella skirt portion in the firing process tends to shrink in the axial direction of the engine valve, the shrinkage is hindered by the weight of the ceramic member 15, and at the time of manufacture. Even after the sintering process for forming the glass coat layer 13, the umbrella back surface 22 a does not cause the end of the glass coat layer 13 on the umbrella skirt side.

In the engine valve of the present invention, a part of the glass coat layer is exposed on the surface, and a portion where the ceramic member and the glass coat layer are bonded is the minimum area necessary for the adhesion. As a result, the stress due to the difference in thermal expansion coefficient between the ceramic member and the glass coat layer can be alleviated as much as possible, and even if the toughness of the glass coat layer is low, the glass coat layer breaks in the sintering process. Damage is prevented.

Although the material of the metal base material which comprises the engine valve of this invention is not specifically limited, The metal conventionally used for the engine valve can be applied.
For example, stainless steel, heat resistant steel, aluminum, aluminum alloy, iron, inconel, hastelloy, invar, and the like can be given. Moreover, various cast products (for example, cast iron, cast steel, carbon steel, etc.) etc. are mentioned.
As a material of the umbrella part of the metal substrate constituting the engine valve of the present invention, heat resistant steel (SUH) may be mentioned. Specifically, martensitic heat resistant steel (SUH3, SUH11, etc.), austenitic heat resistant steel (SUH35, etc.), ferritic heat resistant steel (SUH446, etc.) and the like can be mentioned. Further, Ni-based heat-resistant alloys such as Inconel (NCF751 etc.) are also included.

In the engine valve of the present invention, in order to improve the adhesion between the metal substrate and the glass coat layer, sandblasting or roughening treatment with chemicals may be applied to the back surface of the umbrella other than the umbrella skirt of the metal substrate. Good.

In the engine valve of the present invention, the surface roughness Rz _JIS of the back surface of the umbrella of the metal substrate formed by the roughening treatment is preferably 0.3 to 20 μm. The surface roughness Rz _JIS described above is a ten-point average roughness defined by JIS B 0601 (2001).
When the surface roughness Rz _JIS of the metal base is less than 0.3 μm, the surface area of the back of the umbrella of the metal base becomes small, so that the adhesion between the back of the metal base and the glass coat layer is sufficient. It becomes difficult to obtain. On the other hand, when the surface roughness Rz _JIS of the metal substrate is more than 20 μm, it is difficult to form a glass coat layer on the metal substrate. This is because when the surface roughness Rz _JIS on the back surface of the umbrella of the metal base material is too large, slurry (composition for forming a glass coat layer) is formed on the concave and convex valleys formed on the back surface of the umbrella of the metal base material. It is thought that this is because a gap is formed in this portion without entering.
The surface roughness _{Rz JIS} of the umbrella back surface of the metal substrate is manufactured by Tokyo Seimitsu Co., it can be measured in accordance with JIS B 0601 (2001) using a Handy Surf E-35B.
The measurement is performed at 25 ° C. and atmospheric pressure.

The shape of the shaft portion constituting the engine valve of the present invention is not particularly limited, but is preferably a cylindrical shape. Moreover, it is preferable that the shape of an umbrella part is a substantially cone shape.

In the engine valve of the present invention, the width of the umbrella skirt is preferably 3 to 20% of the width of the umbrella back in the direction from the umbrella skirt on the back of the umbrella toward the shaft of the engine valve. Moreover, it is preferable that the area of the umbrella skirt part in the back of the umbrella is 5 to 50% of the area of the back of the umbrella.

In the engine valve of the present invention, the ceramic member has a ring shape, and a concave portion is formed in a portion adjacent to the umbrella skirt portion on the back surface of the umbrella, and the end portion of the glass coat layer enters the concave portion. The ring-shaped ceramic member is preferably fitted into a recess in which the glass coat layer is formed.
When the engine valve of the present invention is configured as described above, the metal base material expands larger than the ceramic member during firing to form the glass coat layer, and is strong when the temperature is returned to room temperature. A so-called “shrink fit” occurs in a fitted state, and the adhesion of the ceramic member to the metal substrate is improved.

In the engine valve described above, a concave portion is formed on the back surface of the umbrella, but the concave portion is not necessarily formed, and the ceramic member is a portion adjacent to the umbrella hem portion of the back surface of the conical umbrella portion without the concave portion. In addition, the glass coating layer and the ceramic member may be bonded to each other, and the glass coating layer and the metal substrate may be bonded to each other. However, considering the shape of the ceramic member and the ease of fixing the metal base to the back of the umbrella, a recess is formed in a portion adjacent to the bottom of the umbrella on the back of the metal base, and the ceramic member is accommodated in the recess. An engine valve having a different structure is easy to manufacture and is preferable. The cross-sectional shape of the recess is not limited to a right triangle, and is preferably an arc shape or a right V shape. In addition, the glass coat layer may be formed also on the axial part of the metal base material, and may be formed also on the umbrella surface of the metal base material.

FIG. 7 is a cross-sectional view further enlarging the cross-sectional view taken along the line AA shown in FIG.
In the engine valve 10 shown in FIG. 7, the width (w ₁ ) of the umbrella bottom is 3 to 20% of the width (w _H ) of the umbrella back in the direction from the umbrella bottom of the umbrella back to the engine valve shaft. It is preferable. Incidentally, _{D 1} the diameter of the head front, _{D 2} the shortest part of a diameter of the recess 220a, _{d 1} the width of the recess, the depth of the recess When _{d 2,} the diameter _{D 1} of the head front is, 20 to 40 mm Is desirable, and D ₂ / D ₁ is desirably 0.35 to 0.85. Further, the width d ₁ of the recess is desirably 2.0 to 4.0 mm, and d ₂ / d ₁ is desirably 0.5 to 2.0.

The ceramic member constituting the engine valve of the present invention is preferably made of a ceramic raw material, and the ceramic raw material is preferably a crystalline inorganic material.
The crystalline inorganic material is preferably made of at least one selected from the group consisting of alumina, zirconia, yttria, calcia, magnesia, ceria, and hafnia. Of these, zirconia is more preferred.

In the engine valve of the present invention, the shape of the ceramic member is not particularly limited, and may be a shape that can cover the end portion of the glass coat layer formed in a portion other than the umbrella hem portion on the back surface of the umbrella of the metal base material. That's fine.
Examples of the shape of the ceramic member include a ring shape and a skirt shape. Among these, a ring shape is preferable. The cross-sectional shape of the ceramic member is not limited to the triangular shape shown in FIG. 1, and examples thereof include a square, a circle, a semicircle, an ellipse, and the like, and preferably a triangular shape.

In the engine valve of the present invention, the ceramic member preferably has pores, and the porosity of the ceramic member is preferably 10 to 60%. The reason why it is desirable to have pores in the ceramic member is that a part of the glass coat raw material penetrates into the pores of the ceramic member during firing and exhibits an anchor effect, so that the adhesion between the glass coat layer and the ceramic member becomes strong. Because.

When the porosity of the ceramic member is less than 10%, it becomes difficult to follow the change in size due to the difference in the coefficient of thermal expansion from the metal base material, and it is easy to break due to the stress generated by the temperature change. If the porosity exceeds 60%, the mechanical strength is lowered and it is easily destroyed.

In the engine valve of the present invention, the porosity of the ceramic member is measured by the Archimedes method. Specifically, the porosity can be measured by the following method.
First, as a pretreatment, a sample to be subjected to porosity measurement is washed with ultrasonic waves using ion-exchanged water and acetone, and then dried at 100 ° C.
Next, the pretreated sample is boiled with ion exchange water for 3 hours to prepare a saturated sample. Subsequently, the saturated sample is hung with a thread in water, and the buoyancy (W1) of the saturated sample is measured with an electronic balance. Further, the mass (W2) of the saturated sample is measured with an electronic balance, dried at 120 ° C. for 60 minutes, and then the mass (W3) of the dried material is measured.
Using the results obtained by the above method, the porosity is calculated by the following calculation formula.
{[Mass of saturated sample (W2) −mass of dried material (W3)] / buoyancy of saturated sample (W1)} × 100 (%)

In the engine valve of the present invention, the size of the ceramic member is not particularly limited, but the glass coat layer on which the ceramic member is disposed is an end portion on the umbrella skirt side of the glass coat layer formed on the umbrella back surface of the metal base material From 3 to 20% of the width of the glass coat layer formed on the back of the umbrella in the direction toward the shaft portion of the engine valve.
Moreover, it is preferable that the area of the glass coat layer in which a ceramic member is arrange | positioned is 5 to 50% of the area of the glass coat layer formed in the umbrella back surface of the metal base material.

When the glass coat layer on which the ceramic member is disposed is in the above range, the glass coat layer (glass paste layer) adjacent to the umbrella skirt in the firing step for forming the glass coat layer is the shaft portion of the engine valve. Even if an attempt is made to shrink in the direction, the shrinkage is hindered by the weight of the ceramic member. For this reason, even if it passes through the sintering process for forming a glass coat layer at the time of manufacture, the edge part by the side of the umbrella bottom of a glass coat layer does not generate | occur | produce in the umbrella back surface. For this reason, the problem that the thickness of the glass coat layer on the back surface of the umbrella becomes thin at the end on the umbrella skirt portion side does not occur, and as a result, high thermal insulation performance can be exhibited.

The glass coat layer constituting the engine valve of the present invention is preferably composed of an amorphous inorganic material and a crystalline inorganic material.
The amorphous inorganic material is preferably made of glass, and more preferably low-softening point glass having a softening point of 300 to 1000 ° C.
Examples of the low softening point glass having a softening point of 300 to 1000 ° C. include SiO ₂ —B ₂ O ₃ —ZnO glass, SiO ₂ —B ₂ O ₃ —Bi ₂ O ₃ glass, and SiO ₂ —PbO glass. SiO ₂ —PbO—B ₂ O ₃ glass, SiO ₂ —B ₂ O ₃ —PbO glass, B ₂ O ₃ —ZnO—PbO glass, B ₂ O ₃ —ZnO—Bi ₂ O ₃ glass, B ₂ O ₃ -Bi ₂ O ₃ based _glass, B ₂ O 3 -ZnO based glass, BaO-SiO ₂ based _glass, SiO ₂ -B ₂ O 3 -RO based _{glass, SiO 2 -B 2 O 3 -R} 2 O-type glass (R is a transition metal) etc. are mentioned.
The softening point is measured using, for example, a glass automatic softening point / strain point measuring device (SSPM-31) manufactured by Opto Corporation, based on the method defined in JIS R 3103-1: 2001. Can do. The measurement is performed at atmospheric pressure.

In the engine valve of the present invention, the crystalline inorganic material is preferably made of at least one selected from the group consisting of alumina, zirconia, yttria, calcia, magnesia, ceria, and hafnia.
The crystalline inorganic material is also preferably an oxide of at least one metal selected from manganese, iron, cobalt, copper, chromium, and nickel.

In the engine valve of the present invention, the content of the crystalline inorganic material contained in the glass coat layer is desirably 1 to 50% by weight, and preferably 10 to 45% by weight, based on the weight of the glass coat layer. Is more desirable.

In the engine valve of the present invention, the glass coat layer preferably has a thickness of 1 to 1000 μm.
For the measurement of the thickness of the glass coat layer, a dual scope MP40 manufactured by Fisher Instruments Inc. can be used. After performing film thickness correction in the film thickness measurement of the dual scope MP40 at any 30 points on the glass coat layer, the film thickness measurement is performed on any 10 points on the glass coat layer, and the measured values are averaged. Thus, the thickness of the glass coat layer can be measured. When film thickness measurement is performed with respect to 10 points, it is desirable to prevent the measurement site from being biased within the measurement region. For example, a method of performing measurement at regular intervals of 1 mm may be used.
When the thickness of the glass coat layer is within the above range, it is possible to prevent a decrease in intake efficiency without the heat of the in-valve being transmitted to the intake. Further, since the heat of the exhaust gas is not easily transmitted to the exhaust valve, and the temperature of the exhaust gas is less likely to decrease, the exhaust gas can be purified by sufficiently warming the carrier when the exhaust gas reaches the carrier. When the thickness of the glass coat layer is less than 1 μm, for example, when pores are to be formed in the glass coat layer, bubbles easily escape from the glass coat layer, resulting in a large surface roughness on the surface of the glass coat layer. Become. Since the back of the umbrella is in contact with the air flow, if the surface roughness increases, heat transfer between the air flow and the glass coat layer increases, and there is a problem in that the heat insulation performance of the glass coat layer decreases. On the other hand, if the thickness of the glass coat layer exceeds 1000 μm, cracks may easily occur in the glass coat layer when a thermal shock or the like is applied to the glass coat layer. There is also a problem that the intake or exhaust path becomes narrow.

In the engine valve of the present invention, the glass coat layer preferably has pores. The average pore diameter of the pores formed in the glass coat layer is preferably 0.5 to 15 μm.
The average pore diameter is more preferably 3 to 13 μm, still more preferably 5 to 10 μm.
When the average pore diameter of the pores is 0.5 to 15 μm, the pores are present as independent pores in the glass coat layer, and function effectively as a structure that enhances heat insulation.

In the engine valve of the present invention, the porosity of the glass coat layer is preferably 10 to 60%.
The porosity is more preferably 15 to 50%, still more preferably 20 to 40%.
When the porosity is 10 to 60%, sufficient heat insulation by the pores is maintained.

In the engine valve of the present invention, the average pore diameter of the pores of the glass coat layer is measured by cutting a portion of the engine valve umbrella where the glass coat layer is formed and observing a cross section using an SEM or the like. Can do.
Specifically, the average pore diameter can be obtained by photographing the SEM image so that the entire area of the glass coat layer in the thickness direction is included, measuring the pore diameters of all the pores, and obtaining the average value. When the shape of the pores is not substantially spherical, the diameter of the pores is the diameter corresponding to the projected area circle (Haywood diameter).
The measurement magnification of SEM is 3000 times when the thickness of the glass coat layer is 1 μm or more and less than 5 μm, 2000 times when the thickness is 5 μm or more and less than 50 μm, 1000 times when it is 50 μm or more and less than 100 μm, and 1000 times when 100 μm or more and less than 300 μm. 500 times, 200 times when 300 μm or more and less than 500 μm, 150 times when 500 μm or more and 1000 μm or less.

In the engine valve of the present invention, the porosity of the glass coat layer is calculated by calculating the bulk density from the weight of the glass coat layer and the thickness of the glass coat layer measured by a film thickness meter (dual scope), and the true density calculated by a pycnometer The ratio is calculated by subtracting the value from 1 and calculating the ratio as a percentage.

In the engine valve of the present invention, the thermal conductivity of the glass coat layer at room temperature is preferably 0.1 to 1.0 W / m · K.
If the thermal conductivity is less than 0.1 W / m · K, the porosity required to achieve the above thermal conductivity is increased, so that the mechanical strength of the formed glass coat layer may be too low. is there. On the other hand, if the thermal conductivity exceeds 1.0 W / m · K, there is a problem that a sufficient heat insulating effect cannot be obtained. In order to obtain a desired heat insulation effect, it is necessary to increase the thickness of the glass coat layer, so that the heat capacity of the glass coat layer is increased.
In addition, the thermal conductivity at 25 ° C. of a member requiring measurement of thermal conductivity such as a glass coat layer can be measured by a laser flash method. Below, the case where the thermal conductivity of a glass coat layer is measured is demonstrated.

The thermal conductivity is measured by the laser flash method by measuring the thermal diffusion coefficient (α). The thermal conductivity (k) is a value calculated from the measured thermal diffusion coefficient (α), specific heat capacity (Cp), and density (ρ).
The thermal diffusion coefficient can be measured under the following conditions.
Measuring device: LFA467 made by NETZSCH
Surface treatment: Graphite spray Measurement temperature: 25 ° C
Measurement atmosphere: N ₂
Sample size: φ10mm, thickness = 2mm
When measuring the thermal diffusion coefficient of a glass coat layer, it measures in the state integrated with a base material, and calculates the thermal diffusion coefficient of only a glass coat layer by multilayer analysis. Further, when measuring the thermal diffusion coefficient of the glass coat layer, the sample is set so that the laser is irradiated perpendicularly to the glass coat layer.

The thermal conductivity (k) is calculated from the following formula.
k = ρ · Cp · α [W / mK]
<Measurement of bulk density (ρ)>
When determining the bulk density of the glass coat layer, first measure the weight of the substrate, then form a glass coat layer on the substrate and then subtract the glass coat layer from the measurement of the weight of the substrate with the glass coat layer. The weight of (= A) is measured. Thereafter, the volume (= B) of the glass coat layer is calculated from the film thickness of the glass coat layer, and A / B is defined as the bulk density.
<Measurement of specific heat capacity (Cp)>
The specific heat capacity can be measured under the following conditions.
Measuring device: Seiko Denshi Kogyo DSC210 type Measuring temperature: 25 ° C
Measurement method: DSC method Measurement atmosphere: Ar
When measuring the specific heat capacity of the glass coat layer, the measurement can be carried out by forming the glass coat layer into a bulk body having a diameter of 4 mm and a thickness of 1 mm.

In an engine valve of the present invention, it is preferable that the thermal resistance of the glass coating layer is 1~10000mm ² · K / W, and more preferably 500~5000mm ² · K / W.
If the thermal resistance is less than 1 mm ² · K / W, the heat insulation is not sufficient, and it is technically difficult to produce a glass coat layer having a thermal resistance exceeding 10,000 mm ² · K / W.
The thermal resistance of the glass coat layer can be calculated by the equation “thermal resistance = thickness of glass coat layer / thermal conductivity of glass coat layer”.

In the engine valve of the present invention, the coating strength of the glass coat layer is preferably 15 to 50 MPa.
The film strength can be measured by the following method.
FIG. 8 is a schematic cross-sectional view of a sample for coating layer strength measurement.
The stud pin 330 is attached to the surface of the glass coat layer 320 of the engine valve 300 with a glass coat layer by using a clip, and is heated and fixed at 150 ° C. for 1 hour to prepare a measurement sample. As the stud pin 330, P / N901106 (2.7 mm epoxy adhesive Al stud pin made by QUAD GROUP) can be used.

FIG. 9 is an external view of a tensile test by a tensile tester.
Using the tensile tester 1000, the stud pin 330 fixed to the glass coat layer 320 is pulled. The coating layer strength is calculated from the maximum value of the force applied until the glass coating layer 320 in contact with the stud pin 330 peels from the base material 310 constituting the engine valve 300 and the cross-sectional area of the stud pin 330. As the tensile tester 1000, Autograph AGS50A manufactured by Shimadzu Corporation can be used. The measurement is performed at 25 ° C. and atmospheric pressure.

In the engine valve of the present invention, the specific heat of the glass coat layer is preferably 650 to 900 J / kgK.
Specific heat can be measured by DSC (differential scanning calorimetry).
Moreover, it is preferable that the heat capacity (heat capacity per unit area) of the glass coat layer is 200 to 2500 [J / m ² · K]. The heat capacity of the glass coat layer can be calculated by multiplying the specific heat, density and film thickness of the glass coat layer.

In the engine valve of the present invention, the surface roughness Rz _JIS of the glass coat layer is preferably 0.05 to 5 μm.
It is technically difficult to produce a glass coat layer having a surface roughness Rz _JIS of less than 0.05 μm. On the other hand, when the surface roughness Rz _JIS of the glass coat layer exceeds 5 μm, there is a problem that the heat transfer coefficient between the intake or exhaust and the glass coat layer increases and the heat insulation performance decreases.

Further, the engine valve of the present invention includes the following configuration.
That is, an engine valve which is another example of the engine valve of the present invention includes a rod-shaped shaft portion and a substantially conical umbrella portion, and the shaft portion includes a metal base material. On the other hand, in the umbrella portion, a glass coat layer is formed on a portion other than the umbrella skirt portion on the back surface of the umbrella, which is the side surface of the umbrella portion of the metal base material. In addition, a ceramic member having a rectangular cross section and a three-dimensional shape is arranged in a portion adjacent to the umbrella hem on the back of the umbrella so as to cover the end of the glass coat layer on the umbrella skirt side. The ceramic member is bonded to the end of the glass coat layer.

In the above-described example of the engine valve of the present invention, no concave portion is formed on the umbrella back surface of the umbrella portion, and the ceramic member is disposed on the planar umbrella back surface. For this reason, even if the glass coat layer (glass paste layer) adjacent to the umbrella skirt in the firing process tries to shrink in the axial direction of the engine valve, the shrinkage is hindered by the weight of the ceramic member, and a glass coat layer is formed during manufacturing. Even if it goes through the sintering process, the end of the glass coat layer on the umbrella skirt portion side does not shrink on the back surface of the umbrella.

In this example, since the ceramic member can be arranged without forming the recess, the manufacturing process can be simplified. However, it is necessary to manufacture the ceramic member so that the inside of the ceramic member is substantially parallel to the back surface of the triangular pyramid umbrella, which makes it difficult to manufacture the ceramic member. Therefore, a method is preferred in which a concave portion is formed on the back surface of the umbrella of the metal base, a honeycomb structure having a shape that can be accommodated in the concave portion is manufactured, and the honeycomb structure is disposed so as to be accommodated in the concave portion. . In that case, the glass coat layer needs to be formed so that the edge part may enter into a recessed part.

The above-described engine valve of the present invention will be further described in detail.
Fig.2 (a) is a perspective view which shows another example of the engine valve of this invention, FIG.2 (b) is a BB sectional drawing of the engine valve shown to Fig.2 (a). Since the materials and characteristics of the members constituting the engine valve of the present invention have been described in the section of the engine valve shown in FIG. 1, the description thereof will be omitted below.

As shown in FIGS. 2 (a) and 2 (b), an engine valve 30 which is an example of the engine valve of the present invention includes a rod-shaped shaft portion 31 and a substantially conical umbrella portion 32. It consists of a metal substrate. On the other hand, in the umbrella part 32, the glass coat layer 33 is formed in parts other than the umbrella skirt part 420 of the umbrella back surface 42a which is a side surface of the umbrella part 42 of a metal base material. Further, in the portion adjacent to the umbrella skirt portion 420 of the umbrella back surface 42a, the ceramic member 35 having a rectangular cross section (see FIG. 2B) and a three-dimensional shape is the umbrella skirt of the glass coat layer 33. The ceramic member 35 is bonded to the end portion of the glass coat layer 33.

In the engine valve 30 shown in FIGS. 2 (a) and 2 (b), no concave portion is formed on the umbrella back surface 42a of the umbrella portion 42, and the ceramic member 35 is disposed on the flat umbrella back surface 42a. Yes. For this reason, even if the glass coat layer 33 (glass paste layer) adjacent to the umbrella skirt portion in the firing process attempts to shrink in the axial direction of the engine valve, the shrinkage is hindered by the weight of the ceramic member 35, and the glass coat layer is produced during production. Even after the sintering step for forming 33, no shrinkage occurs at the end of the glass coat layer 33 on the umbrella skirt side on the back surface of the umbrella.

In this example, since the ceramic member 35 can be disposed without forming the recess, the manufacturing process can be simplified. However, it is necessary to manufacture the ceramic member so that the inside of the ceramic member 35 is substantially parallel to the triangular pyramid-shaped umbrella back surface 42a, and the manufacturing method of the ceramic member 35 becomes difficult. Therefore, a method is preferred in which a concave portion is formed on the back surface of the umbrella of the metal base, a honeycomb structure having a shape that can be accommodated in the concave portion is manufactured, and the honeycomb structure is disposed so as to be accommodated in the concave portion. . In that case, the glass coat layer needs to be formed so that the edge part may enter into a recessed part.

Examples of the engine valve of the present invention include the following configurations.
In the engine valve, the shaft portion of the engine valve has a rod shape and is made of a metal substrate.
In the umbrella portion of the engine valve, a glass coat layer is formed on a portion other than the umbrella skirt portion on the back surface of the umbrella, which is the side surface of the umbrella portion of the metal base material. Moreover, the recessed part is formed by the cutting process in the part adjacent to the umbrella skirt part of an umbrella back surface, and the edge part of the glass coat layer has entered the inside of a recessed part. A ceramic member having a rectangular cross section and a ring shape in a three-dimensional shape is accommodated in the recess and disposed so as to cover the end of the glass coat layer on the umbrella skirt side. A ceramic member is bonded to the portion. The shape of the recess is a right-angled V-shape.

The engine valve will be further described in detail.
FIG. 3 is a longitudinal sectional view showing still another example of the engine valve of the present invention. The longitudinal sectional view shown in FIG. 3 is a sectional view showing the same cross section as the sectional view taken along the line BB of the engine valve shown in FIG.

Since the shaft portion 51 of the engine valve 50 is configured in the same manner as the shaft portion 31 of the engine valve 30 shown in FIG. 2A, the illustration is omitted here.
As shown in FIG. 3, in the umbrella part 52 of this engine valve 50, the glass coat layer 53 is formed in parts other than the umbrella skirt part 620 of the umbrella back surface 62a which is the side surface of the umbrella part 62 of a metal base material. . Moreover, the recessed part 620a is formed in the part adjacent to the umbrella skirt part 620 of the umbrella back surface 62a, and the edge part of the glass coat layer 53 has entered the inside of the recessed part 620a. The ceramic member 55 having a rectangular cross section (see FIG. 3) and a three-dimensional shape is accommodated in the recess 620a and arranged to cover the end of the glass coat layer 53 on the umbrella skirt 620 side. The ceramic member 55 is bonded to the end portion of the glass coat layer 53. Moreover, the shape of the recessed part 620a is a right-angled V-shape.

The shaft portion 51 of the engine valve 70 is configured in the same manner as the shaft portion 31 of the engine valve 30 shown in FIG.
As shown in FIG. 4, in the umbrella part 72 of this engine valve 70, the glass coat layer 73 is formed in parts other than the umbrella skirt part 820 of the umbrella back surface 82a which is the side surface of the umbrella part 82 of a metal base material. . Moreover, the recessed part 820a is formed in the part adjacent to the umbrella skirt part 820 of the umbrella back surface 82a, and the edge part of the glass coat layer 73 has entered the inside of the recessed part 820a. The ceramic member 75 having a circular cross section (see FIG. 4) and a three-dimensional shape is accommodated in the recess 820a and is arranged so as to cover the end of the glass coat layer 73 on the umbrella skirt 820 side. The ceramic member 75 is bonded to the end portion of the glass coat layer 73.

Examples of the engine valve of the present invention include the following configurations.
The shaft portion of the engine valve is rod-shaped and made of a metal substrate. In the umbrella portion of the engine valve, a glass coat layer is formed on a portion other than the umbrella skirt portion on the back surface of the umbrella, which is the side surface of the umbrella portion of the metal base material. Moreover, the recessed part is formed by the cutting process in the part adjacent to the umbrella skirt part of an umbrella back surface, and the edge part of the glass coat layer has entered the inside of a recessed part. The ceramic member having a circular cross section and a ring shape in a three-dimensional shape is accommodated in the recess and arranged to cover the end of the glass coat layer on the umbrella skirt side, and the end of the glass coat layer A ceramic member is bonded to the portion. The shape of the recess is an arc shape.

The above-described engine valve of the present invention will be further described in detail.
FIG. 4 is a longitudinal sectional view showing still another example of the engine valve of the present invention. The longitudinal sectional view shown in FIG. 4 is a sectional view showing the same cross section as the sectional view taken along the line BB of the engine valve shown in FIG.

The shaft portion 51 of the engine valve 70 is configured in the same manner as the shaft portion 31 of the engine valve 30 shown in FIG.
As shown in FIG. 4, in the umbrella part 72 of this engine valve 70, the glass coat layer 73 is formed in parts other than the umbrella skirt part 820 of the umbrella back surface 82a which is the side surface of the umbrella part 82 of a metal base material. . Moreover, the recessed part 820a is formed in the part adjacent to the umbrella skirt part 820 of the umbrella back surface 82a, and the edge part of the glass coat layer 73 has entered the inside of the recessed part 820a. The ceramic member 75 having a circular cross section (see FIG. 4) and a three-dimensional shape is accommodated in the recess 820a and is arranged so as to cover the end of the glass coat layer 73 on the umbrella skirt 820 side. The ceramic member 75 is bonded to the end portion of the glass coat layer 73. Moreover, the shape of the recessed part 820a is circular arc shape.

Examples of the engine valve of the present invention include the following configurations.
The shaft portion of the engine valve is a rod-like shaft portion made of a metal substrate. In the umbrella portion of the engine valve, a glass coat layer is formed on a portion other than the umbrella skirt portion on the back surface of the umbrella, which is the side surface of the umbrella portion of the metal base material. Moreover, the recessed part is formed by the cutting process in the part adjacent to the umbrella skirt part of an umbrella back surface, and the edge part of the glass coat layer has entered the inside of a recessed part. A ceramic member having a semicircular cross-section and a ring-shaped three-dimensional shape is accommodated in the recess and arranged to cover the end portion of the glass coat layer on the umbrella skirt side. A ceramic member is bonded to the end. The shape of the recess is an arc shape.

In the above-described engine valve of the present invention, a concave portion is formed on the back surface of the umbrella portion, and the end portion of the glass coat layer enters the inside of the concave portion. The ceramic member is accommodated in the recess and is disposed so as to cover the end of the glass coat layer on the umbrella skirt side, and the ceramic member is bonded to the end of the glass coat layer. For this reason, even if the glass coat layer (glass paste layer) adjacent to the umbrella skirt in the firing process tries to shrink in the axial direction of the engine valve, the shrinkage is hindered by the weight of the ceramic member, and a glass coat layer is formed during manufacturing. Even if it goes through the sintering process, the end of the glass coat layer on the umbrella skirt portion side does not shrink on the back surface of the umbrella.

The above-described engine valve of the present invention will be further described in detail.
FIG. 5 is a longitudinal sectional view showing still another example of the engine valve of the present invention. The longitudinal sectional view shown in FIG. 5 is a sectional view showing the same cross section as the sectional view taken along the line BB of the engine valve shown in FIG.

Since the shaft portion 91 of the engine valve 90 is configured in the same manner as the shaft portion 31 of the engine valve 30 shown in FIG. 2A, the illustration is omitted here.
As shown in FIG. 5, in the umbrella part 92 of this engine valve 90, the glass coat layer 93 is formed in parts other than the umbrella skirt part 1020 of the umbrella back surface 102a which is the side surface of the umbrella part 102 of a metal base material. . Moreover, the recessed part 1020a is formed in the part adjacent to the umbrella skirt part 1020 of the umbrella back surface 102a, and the edge part of the glass coat layer 93 has entered the inside of the recessed part 1020a. The ceramic member 95 having a semicircular cross section (see FIG. 5) and a three-dimensional shape is accommodated in the recess 1020a so as to cover the end of the glass coat layer 93 on the umbrella skirt 1020 side. The ceramic member 95 is bonded to the end of the glass coat layer 93. Moreover, the shape of the recessed part 1020a is circular arc shape.

In the engine valves 50, 70 and 90 of the present invention shown in FIGS. 3, 4 and 5, the concave portions 620a, 820a and 1020a are formed on the umbrella back surfaces 62a, 82a and 102a of the umbrella portions 62, 82 and 102, respectively. In addition, the end portions of the glass coat layers 53, 73, and 93 enter the recesses 620a, 820a, and 1020a. The ceramic members 55, 75, and 95 are accommodated in the recesses 620a, 820a, and 1020a, and are disposed so as to cover the end portions of the glass coat layers 53, 73, and 93 on the umbrella skirt portions 620, 820, and 1020 side. Ceramic members 55, 75, and 95 are bonded to the end portions of the coat layers 53, 73, and 93. Therefore, even if the glass coat layers 53, 73, 93 (glass paste layer) adjacent to the umbrella skirts 620, 820, 1020 in the firing process try to shrink in the axial direction of the engine valve, the ceramic members 55, 75, 95 Shrinkage is hindered by the weight of the umbrella, and the umbrella bottom portions of the glass coat layers 53, 73, 93 on the umbrella back surfaces 62a, 82a, 102a even after the sintering process for forming the glass coat layers 53, 73, 93 during manufacturing. No shrinkage occurs at the ends on the 620, 820, 1020 side.

The engine valve of the present invention is used for an engine.
Here, an example of the structure of an engine using an engine valve will be described.
In the engine combustion chamber, an intake engine valve and an exhaust engine valve (exhaust valve) are arranged on the upper part of a cylindrical cylinder. A spark plug is provided at the top of the cylinder, and a piston is provided inside the cylinder.

The engine valve of the present invention is most suitable for the engine combustion chamber having such a configuration.
The back surface of the umbrella of the engine valve is a side surface of the umbrella portion of the engine valve, and means a surface that does not face the engine combustion chamber in the umbrella portion of the engine valve. Moreover, the umbrella skirt part of the umbrella back surface in which the glass coat layer is not formed is a part which contacts a cylinder.

Although the engine valve for intake and the engine valve for exhaust have the same configuration, in the following description, when it is necessary to distinguish between the two, the engine valve for intake is referred to as an in-valve, and the engine valve for exhaust is used. Is described as an exhaust valve, and when it is not necessary to distinguish between the two, it is simply described as an engine valve.

The engine valve has a high heat insulating property because a glass coat layer is formed on the back surface of the umbrella of the in-valve and the exhaust valve. Therefore, the following effects are exhibited.
Since the in-valve has high thermal insulation, the heat of the in-valve is difficult to be transmitted to the fuel that is sucked. Therefore, the engine can be driven without reducing the intake efficiency.
Moreover, since the exhaust valve has high heat insulating properties, the heat of the exhaust gas is difficult to be transmitted to the exhaust valve. Therefore, the temperature of the exhaust gas is unlikely to decrease. Exhaust gas will be purified by the carrier installed in the exhaust gas purification device installed downstream of the engine. The exhaust gas purification function can be suitably exhibited. That is, exhaust gas purification efficiency is improved.

Further, when the engine is driven, fuel is sucked and exhaust gas is discharged. At this time, the engine valve repeatedly contacts the cylinder.
In the engine valve of the present invention, when the glass coat layer is formed by sintering, a strong adhesive force is developed between the metal substrate and the glass coat layer and between the glass coat layer and the ceramic member. For this reason, even in a harsh environment where the engine valve is used, the glass coat layer formed on the back surface of the umbrella of the engine valve is difficult to peel off from the metal base material, and high heat insulation performance can be exhibited.

The engine in which the engine valve of the present invention is used will be further described in detail.
FIG. 6 is a cross-sectional view schematically showing an example of the structure of an engine combustion chamber in which the engine valve of the present invention is used.

As shown in FIG. 6, in the engine combustion chamber 150, an intake engine valve 160 (in-valve 160 a) and an exhaust engine valve 160 (exhaust valve 160 b) are disposed above a cylindrical cylinder 170. A spark plug 180 is provided at the top of the cylinder 170, and a piston 190 is provided inside the cylinder 170.
The engine valve of the present invention is most suitable for the engine combustion chamber having such a configuration.
The umbrella back surfaces 166 a and 166 b of the engine valve 160 are side surfaces of the umbrella portion 166 of the engine valve 160, and mean surfaces of the umbrella portion 166 of the engine valve 160 that do not face the engine combustion chamber 150. . Moreover, the umbrella skirt part 1660 on the back surface of the umbrella where the glass coat layer is not formed is a part in contact with the cylinder 170. In addition, about the position of a glass coat layer, etc., since it has shown with the engine valve shown in FIGS. 1-5, it does not show in figure here.

Although the intake engine valve 160 and the exhaust engine valve 160 have the same configuration, in the following description, when it is necessary to distinguish between the two, the intake engine valve 160 is referred to as an in-valve 160a, and the exhaust The engine valve 160 for use is described as an exhaust valve 160b, and when it is not necessary to distinguish between the two, it is simply described as the engine valve 160.

Since the glass coat layer is formed on the back of the umbrella of the in-bulb 160a and the exhaust valve 160b, the heat insulation is high. Therefore, the following effects are exhibited.
Since the in-valve 160a has high heat insulating properties, the heat of the in-valve 160a is not easily transmitted to the fuel that is taken in. Therefore, the engine can be driven without reducing the intake efficiency.
Further, since the exhaust valve 160b has high heat insulating properties, the heat of exhaust gas is difficult to be transmitted to the exhaust valve 160b. Therefore, the temperature of the exhaust gas is unlikely to decrease. The exhaust gas is purified by the carrier installed in the exhaust gas purification device installed downstream of the engine. If the temperature of the exhaust gas is not lowered, the exhaust gas quickly raises the temperature of the carrier, The exhaust gas purification function can be suitably exhibited. That is, exhaust gas purification efficiency is improved.

Further, when the engine is driven, fuel is sucked and exhaust gas is discharged. At this time, the engine valve 160 repeatedly comes into contact with the cylinder 170.
In the engine valve of the present invention, when the glass coat layer is formed by sintering, a strong adhesive force is developed between the metal substrate and the glass coat layer and between the glass coat layer and the ceramic member. For this reason, even in a harsh environment where the engine valve is used, the glass coat layer formed on the back surface of the umbrella of the engine valve is difficult to peel off from the metal base material, and high heat insulation performance can be exhibited.

Next, a method for manufacturing the engine valve of the present invention will be described.
As a method of manufacturing the engine valve of the present invention,
A step of forming a glass paste layer by applying a glass paste to a portion other than the umbrella hem on the back of the umbrella, which is the side of the umbrella part of the metal base composed of the umbrella part and the shaft part,
A step of disposing a ceramic member on a part of the surface of the glass paste layer so as to cover an end of the glass paste layer on the umbrella skirt side; and
A method for producing the glass paste layer is formed by sintering the glass paste layer, and includes a step of bonding the ceramic member and the metal substrate through the glass coat layer. .
The above-described method for manufacturing an engine valve is also included in the present invention.

(A) Preparation of Metal Base In the method for manufacturing an engine valve of the present invention, first, a metal base constituting the engine valve is prepared.

Since the shape, material, and the like of the metal base are the same as those described in the description of the engine valve of the present invention, the description thereof is omitted here. You may form the recessed part for accommodating a ceramic member in the part which the umbrella base part of a metal base material adjoins.

In preparing the metal substrate, it is preferable to perform a cleaning treatment to remove impurities on the back surface of the umbrella, which is a surface on which the glass coat layer is formed.
The cleaning treatment is not particularly limited, and a conventionally known cleaning treatment method can be used. Specifically, for example, a method of performing ultrasonic cleaning in an alcohol solvent can be used.

When it is desired to further improve the adhesion between the umbrella back surface of the metal substrate and the glass coat layer, the umbrella back surface may be roughened. Examples of the roughening treatment include sand blast treatment, etching treatment, and high temperature oxidation treatment. These may be used alone or in combination of two or more. You may perform a washing process after this roughening process.
In addition, it is preferable to perform a roughening process prior to the process of forming the glass paste layer mentioned later.

(B) Step of forming a glass paste layer (b-1) Glass paste preparation step In the glass paste preparation step in the method for manufacturing an engine valve of the present invention, a glass paste for forming a glass paste layer following the above steps. To prepare.
The glass paste is obtained by mixing glass raw materials. When carbon particles for forming pores are added to the glass paste, the glass raw material and carbon particles are mixed.

The amount of the carbon particles is preferably 0.005 to 1 part by weight, more preferably 0.008 to 1 part by weight with respect to 100 parts by weight of the entire glass coat layer.

The carbon particles are preferably particles that can be vaporized by heat treatment to form pores, and are materials that are blended as a material for forming pores in the glass coat layer in the course of manufacturing an engine valve. .

As specific examples of the carbon particles, graphite particles are preferable, and specifically, ET-10 manufactured by Ibiden Co., Ltd., pitch, coke and the like are preferably used.
Moreover, it is preferable that the average particle diameter of a carbon particle is 0.1-30 micrometers.

In the method for producing an engine valve of the present invention, the raw material mixture can be obtained, for example, by mixing a glass raw material, water, and optionally added carbon particles, and wet-mixing with a ball mill or the like. The order and combination of mixing the three components are not particularly limited. For example, the glass raw material and water may be mixed first, and then carbon particles may be added, or water may be added after mixing the glass raw material and carbon particles. Alternatively, the glass raw material, carbon particles, and water may be mixed at a time.

When the glass paste contains carbon particles, the carbon particles burn in the subsequent firing step to generate CO and CO ₂ to form pores. That is, the carbon particles function as a pore forming agent.

The compounding ratio of the glass raw material and water is not particularly limited, but is preferably about 100 parts by weight of water with respect to 100 parts by weight of the glass raw material. This is because, when the glass raw material and water are mixed at such a weight ratio, the viscosity is suitable for application to the back of the engine valve umbrella. Moreover, you may mix | blend dispersion media, such as an organic solvent, and an organic binder with the said glass paste as needed.

In the method for producing an engine valve of the present invention, as the dispersion medium, for example, water or an organic solvent such as methanol or ethanol can be used. Although content of the dispersion medium in a glass paste is not specifically limited, For example, it is preferable that a dispersion medium is 50-150 weight part with respect to 100 weight part of glass raw materials. This is because, by blending the dispersion medium at such a ratio, the viscosity of the glass paste becomes a viscosity suitable for application to the back of the umbrella of the metal substrate.
Examples of the organic binder include polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and the like. These may be used alone or in combination of two or more. Further, a dispersion medium and an organic binder may be used in combination.

In the method for producing an engine valve of the present invention, the content of carbon particles in the glass paste is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the glass raw material.
The content of carbon particles is more preferably 0.005 to 8 parts by weight, and further preferably 0.008 to 5 parts by weight.
By setting the content of the carbon particles in such a range, a glass coat layer having mechanical strength and heat insulation performance can be formed.

In the method for manufacturing an engine valve of the present invention, a crystalline inorganic material may be further added to the glass paste as necessary.
When the crystalline inorganic material is added to the glass paste, the timing of adding the crystalline inorganic material is not particularly limited. For example, before mixing the glass raw material, water, and optionally added carbon particles, the glass raw material is mixed. And a step of mixing the crystalline inorganic material.
Since the crystalline inorganic material is the same as that described in the description of the engine valve of the present invention, the description thereof is omitted here.
In addition, when adding a crystalline inorganic material as a glass paste, it has the process of mixing a glass raw material and a crystalline inorganic material before mixing the glass raw material mentioned above, water, and the carbon particle added as needed. May be.

(B-2) Coating process As a coating process in the method for manufacturing an engine valve of the present invention, a glass paste for forming a glass paste layer is applied to a portion other than the umbrella skirt on the back of the umbrella of the metal substrate. A glass paste layer is formed.

In the engine valve manufacturing method of the present invention, the thickness of the glass paste layer is not particularly limited, but is preferably 2 to 2000 μm, and a glass coat layer having a thickness of 1 to 1000 μm can be formed. A thickness is preferred.
When the thickness of the glass paste layer is less than 2 μm, for example, when pores are to be formed in the glass coat layer, bubbles easily escape from the glass coat layer, resulting in a large surface roughness on the surface of the glass coat layer. Become. Since the back of the umbrella is in contact with the air flow, if the surface roughness increases, heat transfer between the air flow and the glass coat layer increases, and there is a problem in that the heat insulation performance decreases. On the other hand, when the thickness of the formed glass paste layer exceeds 2000 μm, cracks are likely to occur when a thermal shock or the like is applied to the formed glass coat layer. There is also a problem that the intake or exhaust path becomes narrow.

In the method for manufacturing an engine valve of the present invention, as a method for forming a glass paste layer on the back of an umbrella of a metal substrate, for example, spray coating, electrostatic coating, dipping, ink jet, spin coating, a stamp, a roller, or the like was used. Examples of the method include transfer and brush coating. When the glass paste layer is formed by spray coating or the like, the portion other than the glass paste layer is covered with a tape or a resin, and after the glass paste layer is formed, the tape or the resin is removed to a predetermined area. A glass paste layer can be formed. When the concave portion is formed on the back surface of the umbrella of the metal base material, a glass paste layer is also formed inside the concave portion.

(C) Step of Disposing Ceramic Member In the step of disposing the ceramic member in the method for manufacturing an engine valve of the present invention, a part of the surface of the glass paste layer is covered with an end portion on the umbrella skirt side of the glass paste layer. A ceramic member is disposed on the surface.
For example, when a ring-shaped ceramic member is used, the ceramic member may be fitted into the umbrella portion of the metal base so as to cover the end portion on the umbrella skirt portion side of the glass paste layer. When a concave portion is formed in a portion adjacent to the umbrella skirt portion on the back of the umbrella, the ceramic member is fitted so that the ceramic member is accommodated in the concave portion. At this time, a glass paste layer bonded to the ceramic member is formed on at least a part of the recess.

(D) Sintering step In the sintering step in the method for manufacturing an engine valve of the present invention, the glass paste layer is sintered to form a glass coat layer, and the ceramic member and the metal substrate are combined with the glass coat layer. Glue through.
For example, when carbon particles are contained in the glass paste, the carbon particles can be vaporized and eliminated in the glass paste layer by the sintering process, and pores can be formed in the glass coat layer.

In the engine valve manufacturing method of the present invention, the glass paste layer can be sintered by subjecting the engine valve on which the glass paste layer is formed to a heat treatment. Moreover, in this invention, before performing sintering, you may perform the drying process for drying a glass paste layer with respect to the engine valve in which the glass paste layer was formed as needed. A drying process can be performed at the temperature of about 50-150 degreeC, for example.
The heat treatment conditions for sintering can be arbitrarily set in consideration of the material of the engine valve, etc., but when the material of the engine valve is stainless steel, it is 400 to 900 ° C., when it is heat resistant steel Is preferably heat-treated at 400 to 1000 ° C. The heating time is preferably 3 to 120 minutes.
Moreover, it is preferable that the heat processing temperature for sintering shall be more than the softening point of a glass raw material. By setting the heating temperature to a temperature equal to or higher than the softening point of the glass raw material, the applied glass raw material is softened and melted, and the formed glass coat layer and the metal substrate engine valve umbrella back firmly adhere to each other.

At this time, the carbon particles contained in the glass paste are dispersed in the softened glass raw material, and pores are formed by causing thermal decomposition.

Below, the effect of the engine valve of this invention is enumerated.
(1) In the engine valve of the present invention, the ceramic member is disposed so as to cover the end of the glass coat layer formed on the back surface of the umbrella of the metal base on the umbrella skirt side, so that the glass coat layer is manufactured at the time of manufacture. Even after the sintering step for forming the film, the end of the glass coat layer on the umbrella skirt portion side does not shrink on the back surface of the umbrella. For this reason, the problem that the thickness of the glass coat layer on the back surface of the umbrella becomes thin at the end of the umbrella skirt portion does not occur, and as a result, the engine valve can exhibit high heat insulation performance.

(2) In the engine valve of the present invention, the metal base and the glass coat layer and the glass coat layer and the ceramic member are in close contact with each other. For this reason, even in a harsh environment where the engine valve is used, the glass coat layer formed on the back surface of the umbrella of the engine valve is difficult to peel off from the metal substrate, and high heat insulation performance can be exhibited.

(3) In the engine valve of the present invention, since part of the glass coat layer is exposed on the surface, it becomes possible to alleviate stress due to the difference in thermal expansion coefficient between the ceramic member and the glass coat layer as much as possible. Even when the toughness of the layer is low, the glass coat layer is prevented from being broken and broken in the sintering process.

In the engine valve of the present invention, the ceramic member has a ring shape, and a concave portion is formed in a portion adjacent to the umbrella skirt portion on the back surface of the umbrella, and the end portion of the glass coat layer enters the concave portion. When the ring-shaped ceramic member is fitted in the recess in which the glass coat layer is formed, the metal base material expands more than the ceramic member during firing to form the glass coat layer. As a result, a so-called “shrink fit” occurs in which a strong fitting state occurs when the temperature is returned to room temperature, and the adhesion of the ceramic member to the metal substrate is improved.

(Example)
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.
Example 1
(A) Engine valve base material preparation step A metal base for an engine valve comprising an umbrella part and a shaft part was prepared. The constituent material of the engine valve base material was stainless steel (SUS430).
The shape of the shaft part of the engine valve base material was a rod-like shape having a diameter of 60 mm and a total length of 110 mm.
The shape of the umbrella portion of the engine valve for the substrate, the diameter D ₁ of the bottom surface (umbrella surface) is circle 30 mm, height was conical shape that is 7 mm (see Fig. 7).

Next, a concave portion (a counterbore portion) was formed by cutting in a portion adjacent to the umbrella skirt portion on the back surface of the umbrella portion of the engine valve base material. Concave cross-sectional shape is a right-angled V-shape as shown in FIG. 7, is circular in plan view, with the shortest diameter portion D ₂ is 15.6mm in diameter, the width of the recess is located in 3.1mm The depth of the recess was 3.1 mm.

(B) Coating layer forming step (b-1) Raw material mixture preparing step Next, 100 parts by weight of barium silicate glass (softening point 770 ° C.) as a ceramic raw material, 100 parts by weight of water, and 1 part by weight of methyl cellulose as an organic binder A raw material mixture was prepared by wet-mixing 0.23 parts by weight of graphitized carbon particles as a pore former with a ball mill or the like.

(B-2) Application step Next, a part for forming a glass coat layer is formed by applying a raw material mixture to a part including a concave part on the back surface of the umbrella of the metal base for an engine valve, except for the bottom part of the umbrella. A coating layer was formed. The thickness of the coating layer was 50 μm.
Subsequently, a ceramic member made of a zirconia sintered body was fitted into the recess so as to be accommodated in the formed recess. The ceramic member had a ring shape with a triangular cross-sectional shape, and the innermost part had a diameter of 15.8 mm and a width of 3 mm. Moreover, it was 16% when the porosity of the ceramic member which consists of a zirconia sintered compact was measured by the above-mentioned Archimedes method.

(C) Heat treatment step Next, the substrate was dried in a dryer at 70 ° C. for 20 minutes.
Furthermore, a glass coat layer having a thickness of 40 μm was formed by heat treatment at 800 ° C. for 90 minutes in a firing furnace in air, and the production of the engine valve was completed.
In the top view seen from the top, the glass coat layer was formed in the annular | circular shape, and the glass coat layer was formed in the part to diameter 5-30mm.
The produced glass coat layer had pores, the porosity was 25%, and the average pore diameter was 4 μm. The thickness of the glass coat layer was determined with a film thickness meter (dual scope), and the average pore diameter was determined using a photograph obtained by photographing the glass coat layer with SEM.
The porosity of the glass coat layer is calculated from the weight of the glass coat layer and the thickness of the glass coat layer measured with a film thickness meter (dual scope), and the ratio of the true density calculated with a pycnometer is calculated. Then, the value was subtracted from 1, and the value as a percentage was calculated as the porosity.
As a specific method of calculating the true density with a pycnometer, the glass coat layer is made into a powder form and measured with a continuous automatic powder true density measuring instrument [Autotrudenser MAT-7000, manufactured by Seishin Enterprise Co., Ltd.]. The measurement solvent is not particularly limited as long as it does not react with the diffusion member to be measured. In Example 1, n-butanol was used.

(Comparative Example 1)
(A) In the engine valve base material preparation step, an engine valve according to Comparative Example 1 was manufactured in the same manner as in Example 1 except that the ceramic member was not disposed in the recess.

(Evaluation of glass coat layer)
Regarding the manufactured engine valve according to Example 1 and the engine valve according to Comparative Example 1, a portion close to the shaft portion was cut in parallel to the shaft portion, and the thickness of the glass coat layer in the cross section was observed with a microscope. As a result, in the engine valve according to Example 1, the glass coat layer did not shrink, and the glass coat layer had a substantially uniform thickness, whereas in the engine valve according to Comparative Example 1, the shrinkage occurred. A portion having a thin thickness or a portion where the glass coat layer was not formed was observed with a width of 5 mm.

10, 30, 50, 70, 90 Engine valve 11, 31, 51, 71, 91 Shaft (engine valve)
12, 32, 52, 72, 92 Umbrella (engine valve)
13, 33, 53, 73, 93 Glass coat layer 15, 35, 55, 75, 95 Ceramic member 22, 42, 62, 82, 102 Umbrella (metal substrate)
22a, 42a, 62a, 82a, 102a Umbrella back surface 220a, 420a, 620a, 820a, 1020a Recess 220, 420, 620, 820, 1020 Umbrella hem

Claims (14)

An engine valve consisting of an umbrella part and a shaft part,
A metal substrate constituting the engine valve;
A glass coat layer formed in a portion other than the umbrella hem portion on the back surface of the umbrella, which is the side surface of the umbrella portion of the metal base, and a portion of the glass coat layer is exposed,
An engine valve comprising a ceramic member disposed on a part of the surface of the glass coat layer so as to cover an end of the glass coat layer on the umbrella skirt side. The engine valve according to claim 1, wherein the ceramic member has pores. The engine valve according to claim 2, wherein a component of the glass coat layer penetrates into the pores of the ceramic member. The engine valve according to claim 1, wherein the glass coat layer has pores. The engine valve according to claim 1, wherein the glass coat layer has a thickness of 1 to 1000 μm. The engine valve according to any one of claims 1 to 5, wherein a width of the umbrella skirt portion is 3 to 20% of a width of the umbrella back surface in a direction from the umbrella skirt of the umbrella back surface toward the shaft portion of the engine valve. . The engine valve according to any one of claims 1 to 6, wherein the glass coat layer comprises an amorphous inorganic material and a crystalline inorganic material. The engine valve according to claim 7, wherein the amorphous inorganic material is a low softening point glass having a softening point of 300 to 1000 ° C. The engine valve according to claim 7, wherein the crystalline inorganic material is at least one selected from the group consisting of alumina, zirconia, yttria, calcia, magnesia, ceria, and hafnia. The engine valve according to claim 1, wherein the ceramic member is made of zirconia. The ceramic member is ring-shaped,
A recess is formed in a portion adjacent to the umbrella hem on the back of the umbrella,
In the concave portion, an end portion of the glass coat layer enters,
The engine valve according to any one of claims 1 to 10, wherein the ring-shaped ceramic member is fitted into a recess in which the glass coat layer is formed. The engine valve according to claim 11, wherein a cross-sectional shape of the recess is an arc shape. The engine valve according to claim 11, wherein a cross-sectional shape of the recess is a right-angled V shape. It is a manufacturing method of the engine valve according to any one of claims 1 to 13,
A step of forming a glass paste layer by applying a glass paste to a portion other than the umbrella hem on the back of the umbrella, which is the side of the umbrella part of the metal base composed of the umbrella part and the shaft part,
A step of disposing a ceramic member on a part of the surface of the glass paste layer so as to cover an end of the glass paste layer on the umbrella skirt side; and
A method for manufacturing an engine valve, comprising: forming a glass coat layer by sintering the glass paste layer; and bonding the ceramic member and the metal substrate through the glass coat layer. .

Images