JPH11247629A - Engine valve made of aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the mechanical strength and wear resistance of an engine valve made of an aluminum alloy by uniformly dispersing ceramic particles having projecting and recessed parts with the rounded outer periphery in a base material made of an aluminium alloy. SOLUTION: The whole of a valve in an engine valve 1 for intake is formed from a raw material made by uniformly dispersing ceramic particles 3 in a base material 2 made of an aluminum alloy. The base material 2 to be used is preferably a non-heat treated aluminum alloy such as JIS 5083 material composed of 4-4.9 wt.% Mg, 0.4 wt.% Si, 0.4 wt.% Fe, 0.4-1.0 wt.% Mn, 0.25 wt.% Zn, 0.15 wt.% Ti, 0.05-0.25 wt.% Cr, 0.1 wt.% Cu and the residue, which is composed of Al and inevitable impurities. As the ceramic particles 3, preferably used is a mixture of one or two kinds such as Al2 O3 , ZrO2 moderately having the projecting and recessed parts on the outer peripheral surface thereof in an arbitrary sectional form, with a mean particle diameter of about 3 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy engine valve having excellent strength and wear resistance, for example, used on the intake side of an internal combustion engine.

[0002]

2. Description of the Related Art Intake and exhaust valves used in internal combustion engines are usually made of martensite or austenitic heat-resistant steel. Recently, attempts have been made to form an intake valve having a relatively small heat load from an aluminum alloy.

[0003]

The above-mentioned heat-resistant steel engine valve has high mechanical strength, excellent durability and reliability, but has a problem of large inertial mass and poor thermal conductivity. is there.

[0004] On the other hand, aluminum alloy valves are lightweight, so that the inertial mass of the valve train can be reduced, engine performance can be improved, heat conductivity is excellent, and heat dissipation to the cylinder head is improved. It has the advantage of being expensive.

However, valves made of aluminum alloy are
Since the mechanical strength is small and there is a problem in abrasion resistance of the valve face portion, the shaft portion, and the like, durability and reliability are lacking.

[0006] In order to solve this problem, the surface layer of the valve face, which particularly requires wear resistance, is modified and hardened by an alloy containing a reinforcing element, or the shaft is treated with a surface treatment such as alumite. It is possible to take countermeasures such as applying or dispersing ceramic particles in a base material made of an aluminum alloy.

However, the above-described modification with a strengthening element or surface treatment such as alumite is a partial measure and does not improve the mechanical strength of the entire valve. The problem remains.

[0008] Dispersing ceramic particles in a substrate has the advantage that the mechanical strength of the entire valve is improved and the wear resistance of the valve face portion, shaft portion, and the like can be improved. Depending on the size and shape of the
The ceramic particles fall off from the surface layer of the base material, and the wear resistance is impaired, and the aggressiveness of the other party is increased, thereby promoting the wear of the valve seat and the valve guide.

The present invention has been made in view of the above problems, and disperses ceramic particles having an optimum size and shape into a base material, so that the ceramic particles fall off or enhance the opponent's aggressiveness. It is an object of the present invention to provide an aluminum alloy engine valve capable of greatly improving mechanical strength and wear resistance without causing the problem.

[0010]

According to the present invention, the above-mentioned problem is solved as follows. (1) Ceramic particles having rounded irregularities on the outer peripheral surface are uniformly dispersed in a base material made of an aluminum alloy.

(2) In the above item (1), the base material is JI
It is assumed that it is made of a 5,000-series aluminum alloy in S.

(3) In the above item (1) or (2), the ceramic particles are made of Al ₂ O ₃ , ZrO ₂ , SiC, Nb
C, Si ₃ N ₄ , BN, CrC, TiB ₂ , or a mixture of two or more.

(4) In any one of the above items (1) to (3), the average particle size of the ceramic particles is set to approximately 3 μm.
The content is at least 15% by volume in the substrate.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an intake engine valve (1) of the present invention. The entire valve is formed by uniformly dispersing ceramic particles (3) in a base material (2) made of an aluminum alloy. I have.

The substrate (2) is made of a non-heat-treated aluminum alloy, that is, one of JIS No. 5000 series.
Species, for example, the composition of the component is Mg: 4 to 4.9% by weight, Si:
0.4 wt%, Fe: 0.4 wt%, Mn: 0.4 to 1.0 wt%, Zn: 0.25 wt%, Ti: 0.15 wt%, C
It is preferable to use a JIS5083 material consisting of r: 0.05 to 0.25% by weight, Cu: 0.1% by weight, and the balance being Al and inevitable impurities. Even if this material is kept at a temperature of, for example, about 250 ° C. for a long time, its hardness hardly changes.

The ceramic particles (3) have an average particle size of about 3 μm (particle size range of 1 to 5 μm) or an average particle size of about −
A having a mesh of 200 and moderate irregularities without any sharp corners on its outer peripheral surface in any cross-sectional shape of the particle.
l ₂ O ₃ , ZrO ₂ , SiC, NbC, Si ₃ N ₄ , BN,
It is preferable to use any one kind of CrC, TiB ₂ or the like, or a mixture of two or more kinds.

The shape of the particles (3) can be specified, for example, by the degree of unevenness (non-circularity) of the cross section of the particles (3) as shown in FIG. That is, assuming that the cross-sectional area of the particle (3) is A, the circumferential length is L, and the pi is π, the degree of irregularity X is
Is

[0018]

(Equation 1) Can be obtained by From the above equation, the value is 1 in the case of a perfect circle having no unevenness, and the larger the unevenness, the longer the circumferential length L
Is larger, the value of X is larger than 1.

Ceramic particles (3) used in the present invention
, The value of X is in the range of 1.3 to 4.0.
In other words, when the value of X is 1.3 or less, as shown in FIG. And wear resistance is impaired. When the value of X is 4.0
4, the particle (3) has a higher resistance to falling off, but the projections on the outer peripheral surface are sharpened, thereby increasing the aggressiveness to the opponent.

In forming an engine valve, first, 70-80% of particles having an average particle diameter of about 3 μm are added to the above-mentioned JIS No. 5,000-series aluminum alloy.
A material containing 15 to 20% by volume of the above-mentioned ceramic particles (3) is produced, and this material is inserted into a mold for molding a valve and forged by hot or warm. Then, as shown in FIG. 1, an engine valve (1) in which the ceramic particles (3) are uniformly dispersed in the substrate (2) is obtained.

In the intake engine valve (1) of the above embodiment, the non-heat-treated JIS 5,000 is applied to the base material (2).
No. 2 aluminum alloy is used, and ceramic particles (3) are dispersed therein, so that the decrease in hardness (strength) due to the operating temperature of the engine is small, and the mechanical strength of the entire valve is increased. Face (1
a) and the abrasion resistance of the shaft portion (1b) and the like can be improved.

Further, by using ceramic particles (3) having irregularities with a rounded cross section,
As shown in FIG. 5, the bond strength with the base material (2) is increased, the drop-out resistance is increased, and no sharp projections are exposed on the surface layer of the base material (2). The nature also decreases.

[0023]

According to the present invention, the following effects can be obtained. (A) By dispersing ceramic particles having rounded irregularities on the outer peripheral surface in a base material made of an aluminum alloy, the ceramic particles may fall off from the base material,
The mechanical strength and wear resistance of the entire engine valve can be greatly improved without increasing the opponent's aggressiveness.

(B) According to the second aspect of the present invention, the decrease in hardness due to the operating temperature of the engine is reduced, so that, for example, the durability and reliability as an intake-side engine valve are improved.

(C) According to the third aspect of the present invention, since all are hard and have a high melting point, the base material is strengthened and the durability of the engine valve is enhanced.

(D) According to the invention as set forth in claim 4, the structure of the base material is densified, the mechanical strength can be increased, and the strength of the entire valve is made uniform.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention.

FIG. 2 is an explanatory view showing an arbitrary cross-sectional shape of ceramic particles.

FIG. 3 is an enlarged cross-sectional view of a surface layer portion of a base material when using ceramic particles having a small degree of unevenness.

FIG. 4 is an enlarged sectional view of a surface layer portion of a base material when ceramic particles having a large degree of unevenness are used.

FIG. 5 is an enlarged cross-sectional view of a surface layer portion of a base material when ceramic particles having an appropriate degree of unevenness are used.

[Explanation of symbols]

 (1) Intake engine valve (1a) Valve face (1b) Shaft (2) Base material (3) Ceramic particles

Claims (4)

[Claims] 1. A substrate made of an aluminum alloy,
An aluminum alloy engine valve characterized by uniformly dispersing ceramic particles having rounded irregularities on an outer peripheral surface. 2. The aluminum alloy engine valve according to claim 1, wherein the base material is made of a 5,000-series aluminum alloy according to JIS. 3. The ceramic particles are made of Al ₂ O ₃ , ZrO
_{2, SiC, NbC, Si 3} N 4, BN, CrC, TiB 2
The aluminum alloy engine valve according to claim 1 or 2, wherein the aluminum alloy engine valve is made of any one of the following, or a mixture of two or more thereof. 4. The method according to claim 1, wherein the average particle size of the ceramic particles is approximately 3 μm.
The aluminum alloy engine valve according to any one of claims 1 to 3, wherein at least 15% by volume of m is contained in the base material.