JP2000008132A - Valve guide made of high silicon aluminum alloy for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve guide enhanced in heat resistance, wear resistance, seizing resistance, scuffing resistance and thermal emission by subjecting the atomized powder of an alloy composed of specified weight ratios of Si, Fe, Cu, Mg and one or more kinds among Zr, Ni, Mn and Zn, and the balance Al to extrusion molding. SOLUTION: The atomized powder of an alloy composed of, by weight, 15 to 40% Si, 1.0 to 10.0% Fe, 0.5 to 5% Cu, 0.1 to 3.0% Mg, one or more kinds of Zr, Ni, Mn and Zn by <3%, and the balance Al is used. Preferably, either or both of hard particles of SiC and Al2O3 having <=5 μm average particle size and a solid lubricant of graphite, sulfide and fluoride are added to this powder by 1 to 10 weight% of the whole weight. As for the high silicon aluminum alloy, by atomizing molten metal by gas atomizing, rapid solidification of >=103K/sec can be executed, and fine powder of precipitates including primary crystal Si is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a valve guide for an internal combustion engine.

[0002]

2. Description of the Related Art A valve guide is a cylindrical member which is fitted into a cylinder head concentrically with a valve stem to guide reciprocating sliding movement of a valve stem such as an intake valve and an exhaust valve of an internal combustion engine. . Here, with the recent demand for higher output of the internal combustion engine, each member inside the internal combustion engine is exposed to a very high combustion temperature, and the valve stem slides on the valve guide at a high speed. As well,
Abrasion resistance and seizure resistance are required. This tendency is particularly remarkable for a valve guide projecting toward the exhaust port for discharging exhaust gas.

When a bending load is applied to the valve stem during operation of the internal combustion engine, a large pressing force is applied to the inner peripheral surfaces at both ends of the valve guide. Furthermore, with the recent trend of a decrease in oil consumption, the amount of oil leaking from the oil stem seal in the valve train of the internal combustion engine has been reduced, and lubrication in sliding between the valve guide and the valve stem has become insufficient. The likelihood of sticking has increased. Due to these recent changes in internal combustion engine conditions, valve guides are required to have high heat resistance, wear resistance and high seizure resistance.

[0004] In order to solve these problems, cast iron materials and iron-based sintered materials having a relatively large mass, in which carbide is precipitated, are widely used as valve guide materials. For example, Japanese Patent Application Laid-Open No. 7-150914 proposes a valve guide for manufacturing a metal material such as an Fe-based sintered material with a partial density change.
In Japanese Patent Laid-Open Publication No. H11-264, a valve guide made of an Fe-based sintered alloy containing carbon, copper, and phosphorus is proposed. A metal material having excellent seizure resistance and abrasion resistance, which is not limited to the purpose used for the valve guide, is disclosed in JP-A-6-73489.
Japanese Patent Laid-Open Publication No. H11-163873 proposes a cast iron containing 20 to 45% by weight of copper and having copper precipitated around graphite, and this cast iron is considered to be used for a valve guide. Can be

[0005]

However, such a valve guide made of a cast iron material or an iron-based sintered material has a heat resistance enough to withstand the recent increase in output of a gasoline engine or a diesel engine and an increase in combustion temperature. It does not have abrasion resistance and seizure resistance. Cast iron and sintered iron valve guides have limited wear resistance and scuff resistance at high temperatures, and have problems maintaining proper sliding of the valve stem and sealing between the valve and valve seat. Is coming out. In addition, high temperature, deformation due to pressing, abrasion or seizure occurs in the valve guide, and when the confidentiality inside the combustion chamber decreases,
As a result, the output of the internal combustion engine is reduced. In addition, cast iron,
The valve guide composed of an iron-based sintered material has a relatively large mass, which hinders the reduction of the mass of the internal combustion engine itself, further causes a decrease in the function of the internal combustion engine, and also has insufficient thermal conductivity. Was.

Accordingly, the present invention provides heat resistance against high-temperature exhaust gas, abrasion resistance against sliding with a valve stem at high temperature, anti-seizure resistance, scuff resistance, and heat conduction for enhancing heat release to the outside of an internal combustion engine. An object of the present invention is to provide a valve guide that solves the problem of sexuality.

[0007]

Means for Solving the Problems To achieve the above object, the means adopted by the present invention is as follows:
40%, Fe: 1.0 to 10.0%, Cu: 0.5 to 5
%, Mg: 0.1 to 3.0%, Zr, Ni, Mn, Zn
One or more of the following: atomized powder of a high silicon aluminum alloy consisting of less than 3%, balance 1: Al; or SiC, A having an average particle size of 5 μm or less.
Hard particles such as l ₂ O ₃ and graphite, sulfides such as MoS ₂ , WS ₂ , MnS, fluorides such as CaF ₂ , L
One or both of solid lubricants such as iF and a mixture of 1 to 10% by weight are extruded to form a valve guide. After molding, if necessary,
Performs age hardening treatment.

[0008] The high silicon aluminum alloy is formed by spraying a molten metal by gas atomization to 10 3 K / sec.
The above-mentioned rapid solidification can be performed, and a high-aluminum aluminum alloy becomes a fine powder of precipitates including primary crystal Si. By heating and extruding this, a valve guide having high heat resistance, wear resistance and seizure resistance can be obtained. In addition, since this valve guide is made of an aluminum alloy having high thermal conductivity, heat release to the outside is better than that of a conventional cast iron.

The reasons for limiting the high silicon aluminum alloy, the hard particles, the components of the solid lubricant and the like of the present invention are as follows. 1) For Si, fine primary crystal Si particles have an effect on abrasion resistance. If the content is less than 15% by weight, the effect is not obtained. If the content is more than 40%, the powder becomes too hard and the extrudability is reduced. become worse.

By adding Fe, the heat resistance can be enhanced. If the content is less than 1.0% by weight, the effect is not obtained, and if it exceeds 10%, the high melting point component is increased, so that the spraying property is increased. Make it difficult. Cu imparts age hardening properties and improves mechanical strength, hardness, and abrasion resistance.
In less than 0.5%, there is no effect, and when it exceeds 5%, the strength and elongation decrease.

Mg imparts age hardening together with Cu,
It improves the mechanical strength, hardness and abrasion resistance. However, if it is less than 0.1% by weight, it is not effective, and if it exceeds 3%, the thermal expansion increases. Zr, Ni, Mn, and Zn have the effect of improving high-temperature strength and thermal expansion. However, if the content exceeds 3% by weight, the strength and elongation decrease. 2) Hard particles have an effect on abrasion resistance, but are not effective at less than 1% by weight and workability is deteriorated at more than 10% by weight. If the average particle size exceeds 5 μm, the partner material is worn. 3) The solid lubricant improves abrasion resistance. However, if it is less than 1% by weight, it is not effective, and if it exceeds 10%, the strength is reduced. When the average particle size exceeds 5 μm, the strength further decreases.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A valve guide according to the present invention will be described with reference to FIG. FIG. 1 is a sectional view of a cylinder head portion of an internal combustion engine, and the cylinder head portion is constituted by a cast cylinder head 1. The upper side of the cylinder head 1 shown in FIG. The cylinder head 1 has a tubular through-hole 1a penetrating the inside of the cylinder and the outside of the cylinder, and an exhaust port 2 for discharging exhaust gas. The opening 2a of the exhaust port 2 has a substantially circular shape, and an annular recessed step 1b for fitting the substantially ring-shaped valve seat 3 is formed around the opening 2a. I have. The valve seat 3 is a member that prevents direct contact between the valve 4 on the inner end side of the valve stem and the cylinder head 1 and protects the cylinder head 1.

A valve stem 5 penetrates through the through-hole 1a, and an elongated cylindrical valve guide 9 formed coaxially with the valve stem 5 is press-fitted between the through-hole 1a and the valve stem 5. And is fixed to the cylinder head 1.
An inner end of the valve guide 9 slightly projects into the exhaust port 2, and an outer end of the valve guide 9 slightly projects from the cylinder head 1. At the outer end of the valve stem 5, a boss-shaped spring retainer 6 that extends in the radial direction of the valve stem is fixed.

The outer end of the valve stem 5 projects slightly from the spring retainer 6 toward the outside of the cylinder. A valve spring 7 is disposed between the spring retainer 6 and the cylinder head 1, and urges the valve guide 5 and the valve 4 upward in FIG.
The outer end face of the valve stem 5 is in contact with a rocker arm 8 that swings around the axis of the shaft 10.

The outer end surface of the valve stem 5 is pressed by the rocker arm 8 swinging counterclockwise, and the valve stem 5 slides downward while sliding against the valve guide 9. With the downward movement of the valve stem 5, the valve 4 integrated with the valve stem 5 also moves downward,
The combustion chamber communicates with the exhaust port 2, and exhaust gas generated in the combustion chamber is led out to the exhaust port 2. At this time, one end of the valve guide 9 on the inner side of the cylinder is exposed to high-temperature and high-pressure exhaust gas. When the rocker arm 8 swings clockwise, the spring force of the valve spring 7 causes the spring retainer 6 and the valve stem 5 and the valve 4 integrated with the spring retainer 6 to move upward. At this time, the valve stem 5 slides again at a high temperature with respect to the valve guide 9 at a high speed, and the valve 4 sits on the valve seat 3 at a high speed.

The valve guide 9 is made of Si: 2 by weight%.
0.0%, Fe: 5.0%, Cu: 1.0%, Mg:
0.5%, Zr: 1.0%, balance: Al: A molten silicon of a high silicon aluminum alloy is rapidly cooled by an atomizing method at an average cooling rate of 10 3 K / sec or more, and powdered.
The powder was extruded at 400 ° C.

[0017]

Next, a comparison test between the valve guide of the present invention and a conventional one will be described. FIG. 2 shows a schematic diagram of a test on a valve guide. The testing machine used was an Amsler-type abrasion testing machine. Rotating piece 11 corresponding to valve guide 9
Is rotatably supported such that the axial direction is horizontal and the vertical lower portion is immersed in the lubricating oil 13. The fixed piece 12 corresponding to the valve stem 5 receives the load P from vertically above and comes into contact with the vertically upper portion of the rotating piece 11 from above. By rotating the rotating piece 11, the rotating piece and the fixed piece 12 are relatively slid, and the amount of wear on the rotating piece 11 (corresponding to the amount of wear of the valve guide) and the amount of wear on the fixed piece 12 (valve stem). (Corresponding to the amount of abrasion).

The test conditions were as follows. Rotating piece rotation speed 1 m / s Lubricating oil SAE # 30 equivalent oil Lubricating oil temperature 80 ° C. Load 80 kg Test time 8 Hr Five kinds of high silicon aluminum alloy of the present invention subjected to the test as a rotating piece and conventional cast iron and iron Table 2 shows the average particle size of the two types of components, the hard particles and the solid lubricant mixed therein. The fixed piece of the sliding partner with respect to the rotating piece is a common material whose base material is made of high-speed tool steel and whose outer peripheral surface is subjected to tufting.

[0019]

[Table 1]

The test results of Examples 1 to 5 and Comparative Examples 1 and 2 are as shown in FIG. 3, and the wear amount of the rotating piece of Examples 1 to 5 was 0.8 to 2.3 μm. 2 itself is much smaller than the wear amount of 5 to 8 μm. Further, the wear amount of the mating fixed pieces of Examples 1 to 5 is 0.5 to 1.5 μm, which is substantially the same as the wear amount of the mating fixed pieces of Comparative Examples 1 and 2 of 0.7 to 1.5 μm. The test results show that the valve guide of the present invention is superior in wear resistance to that of the conventional cast iron or iron-based sintered alloy.

[0021]

As described above, since the valve guide for an internal combustion engine of the present invention is formed by extruding high silicon aluminum alloy powder, it is compared with conventional cast iron or iron-based sintered alloy. It has the effect of excellent heat release to the outside of the internal combustion engine and good wear resistance, sintering resistance and scuff resistance at high temperatures.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a valve train for an internal combustion engine having a valve guide.

FIG. 2 is a schematic diagram showing a wear test of a valve guide;

FIG. 3 is a graph showing a wear test result of a valve guide;

[Explanation of symbols]

 1: Cylinder head, 1a: Through port, 1b: Stepped portion 2: Exhaust port, 2a: Opening 3: Valve seat 4: Valve 5: Valve stem 6: Spring retainer 7: Valve spring 8: Rocker arm 9: Valve guide 10: Shaft 11: Rotating piece 12: Fixed piece 13: Lubricating oil

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 1/04 B22F 5/00 Z

Claims (2)

[Claims] 1. The method according to claim 1, wherein Si is 15 to 40% by weight and Fe:
1.0-10.0%, Cu: 0.5-5%, Mg: 0.
1 to 3.0%, one or more of Zr, Ni, Mn and Zn: less than 3%, balance: high silicon aluminum alloy for internal combustion engines obtained by extrusion molding of an alloy spray powder consisting of Al Valve guide. 2. The method according to claim 1, wherein said powder has an average particle size of 5 μm or less.
C, a hard particle made of Al ₂ O ₃ and / or a solid lubricant made of graphite, sulfide, or fluoride added in an amount of 1 to 10% by weight in total. Silicon aluminum alloy valve guide.