JPH01156453A - Valve gear mechanism member for internal combustion engine - Google Patents

Abstract

PURPOSE:To obtain a valve gear mechanism member for internal combustion engine excellent in wear resistance and scuffing resistance and reduced in damage to mating sliding material by subjecting an alloy powder prepared by blending powders of the oxides of specific metals and a graphite powder and reducing the resulting mixture to compacting and sintering. CONSTITUTION:A graphite powder is blended with respective powders of Fe2O3, MoO3, NiO, Cr2O3, WO3, V2O5, and Nb2O5 of <=5mum grain size, and the resulting powder mixture is heated in an ammonia decomposed gas atmosphere to under go the reduction of the above-mentioned respective metal oxides by means of the graphite powder, by which an alloy powder having a composition consisting of, by weight, 1-4% C, 10-40% Mo, 3-20% Cr, 1-10% Ni, at least one kind among 0.05-1% Nb, 0.3-5% W, and 0.1-3% V, and the balance Fe is formed. By subjecting this powder to compacting and sintering, the valve gear mechanism member for internal combustion engine having a structure in which nearly spherical closed pores of >98% density ratio and <5mum diameter are uniformly dispersed and also spherical hard carbides of <10mum average grain size are uniformly dispersed in 10-40% area ratio and excellent in wear resistance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a valve train member for an internal combustion engine, and more specifically, to a valve train member constituting a valve train mechanism for an internal combustion engine used in an automobile or the like. The present invention relates to valve train members of internal combustion engines, such as rocker arms and valve lifters, which require excellent wear resistance in the surrounding parts with cams and the like.

[Prior Art] In the valve train of an internal combustion engine, the rocker arm, valve lifter, and other valve drive system members that convert the rotational movement of a cam into the vertical movement of a valve are subject to complicated actions such as bending, tension, and compression. Not only is it necessary to have sufficient mechanical properties to withstand the stress caused by the stress, but especially in WIiIJ parts with other parts (cams, valves, etc.) There is a need for a material that has excellent performance and less damage to the mating material on which it slides.

Therefore, conventionally, the main body parts of internal combustion engine valve train parts such as rocker arms and valve lifters are generally made of carbon steel, alloy steel, etc., and the sliding surface with the cam is made of abrasion-resistant material. In order to improve the properties, carburizing and quenching treatment,
It was common practice to use chill hardening treatment, hard chrome plating treatment, thermal spraying treatment of self-fluxing alloys, etc.

[Problems to be Solved by the Invention] However, carburized and quenched products have poor scuffing resistance, and chill-hardened products have poor durability as sliding members.

In addition, in hard chrome plated products, peeling or abrasion of the hard chrome plating may occur due to local contact during internal combustion engine operation, and in thermal sprayed products made of self-fluxing alloys, there is a risk of damage to sliding mating materials. Each of the above-mentioned materials and treatments used for conventional internal combustion engine valve train components has its own problems, such as increased damage and severe cam wear, and the development of better internal combustion engine valve train components is necessary. is desired.

To solve the above problems, Japanese Patent Application Laid-Open No. 60-19404
In Publication No. 8, C: 1 to 4%, 1ylo: 1o to 4
There is a disclosure of a sintered alloy having a composition of 0% Cr, 3 to 20% Cr, 1 to 10% CO, and the remainder substantially Fe. This sintered alloy still has insufficient improvement in corrosion resistance and attack resistance, and improvements in this respect have been desired.

Therefore, the present invention was made to solve the above-mentioned problems of the prior art.In particular, in order to improve the aggressiveness against opponents, fine gold containing each metal element to have a specific composition after reduction is prepared. By molding and sintering the alloy powder produced by adding graphite powder to a mixed powder containing ffi oxide and reducing it, it has excellent wear resistance and scuffing resistance.
Moreover, it is an object of the present invention to provide a valve train member for an internal combustion engine that is less likely to cause damage to sliding mating members, especially cam wear.

[Means for Solving the Problems] The valve train member of the internal combustion engine of the present invention has a composition after reduction in weight ratio of C: 1 to 4%, Mo: 10 to 40%, and Cr:
3-20%, N+: 1-10%, and Nb: 0.05
-1%, W: 0.3-5%, ■: 0.1-3%, the balance is substantially Fe (iron), and the fine particles containing each of the metal elements mentioned above. It is characterized by being a metal sintered body formed by molding and sintering an alloy powder produced by mixing graphite powder with a mixed powder containing metal oxide powder and reducing the mixture.

The composition of the alloy powder constituting the metal sintered body of the present invention will be explained.

MO is useful because it reacts with C to form carbides and improve wear resistance, and a portion of it is solidly dissolved in the base structure to strengthen the base structure, but if the content is less than 10%, it will not form. Since the amount of carbide formed is small, the wear resistance is not sufficiently improved, and the strength of the base structure is also insufficient, which increases the wear of the valve train parts themselves.If the amount exceeds 40%, the amount of carbide in the structure increases. 10 to 4 because if there is an excessive amount of
Use 0%.

In addition, like MO, Or reacts with C to form carbides to improve wear resistance, and a portion of Or is solidly dissolved in the base structure to increase the strength of the base structure and improve corrosion resistance. Although it is effective, if it is less than 3%, the amount of carbide formed in the structure is extremely small and the wear resistance and corrosion resistance are insufficient.On the other hand, if it exceeds 20%, the amount of carbide formed is excessive and it is difficult to wear. It increases the damage to moving mating materials and significantly reduces toughness, so it is used at a maximum of 3 to 20%.

In addition, C strengthens the base organization and 1ylo.

Reacts with Cr'= to form M@C, M7C3, M23G@,
It is effective in forming M2C type carbides and improving wear resistance, but if it is less than 1%, the amount of precipitated carbide is small, so the above effect is not sufficient, and if it exceeds 4%, the M2C type carbide is effective in improving wear resistance.
Since most of O1Cr forms carbides and the MO and Cr dissolved in solid solution in the base structure become insufficient, the abrasion resistance and corrosion resistance are lowered, so 1 to 4% of O1Cr is used.

In addition, Ni is effective because it dissolves in the base structure and strengthens the base structure, but if it is less than 1%, the effect is not sufficient.
If it exceeds 10%, the strength will actually decrease, so 1.
~10% floor is used.

Furthermore, W, V, and Nb all react with C to form hard fine carbides and are effective in improving wear resistance, but W is less than 0.3%, and ■ is 0.3%. Less than 1%, Nb
If it is less than 0.05%, the effect is not sufficient because the amount of precipitated carbide is small, W is 5%, ■ is 3%, and Nb is 1%.
W is 0.3 to 5%;
(2) is 0.1 to 3%, and Nb is 0.05 to 1% for ffi.

By using at least one of the above-mentioned Ni, W1, and Nb, the member obtained from this sintered alloy was able to improve the wear resistance and damage resistance of the mating material.

The reason why the fine metal oxide powder of each metal element is reduced using graphite powder is as follows.

That is, conventional methods for producing alloy powders use a spraying method, a pulverization method, a reduction method, etc., but in the present invention, since the metal oxide powder that is the raw material is finely pulverized (
The average particle size is 3 μm or less), and the reduction temperature during reduction can be set to a relatively low temperature (900 to 1000°C), and the alloy powder particles will not be strongly sintered or grain grown (mutual) during the reduction process. It becomes a weakly bonded state, and can be easily made into a fine alloy powder with a particle size of 10 um or less by pulverization.

Furthermore, since the fine alloy powder produced by reducing graphite powder has excellent activity, it has excellent sinterability, and alloying and carbide formation reactions can proceed easily.

Therefore, although the alloy powder is a fine powder, it has excellent compression moldability and can be easily compacted using a normal molding method. The compact is then sintered under normal conditions. i.e. 1100 under inert gas
It is preferable to conduct the reaction at a temperature of 1200°C to 1200°C.

If the density ratio of the obtained metal sintered body is less than 98%, there will be too many residual pores, which will increase pitting resistance, abrasion resistance, and damage to the sliding mating material. Therefore, the density ratio should be 98% or more. is desirable.

Furthermore, if the diameter of the residual pores exceeds 5 μm, the above-mentioned characteristics deteriorate, so it is desirable that the residual pores be as small as 5 μm or less.

Furthermore, the closer the shape of the residual pores is to a spherical shape, the better the pitting resistance is, and the fact that the residual pores are closed pores improves the lubricating oil retention effect and makes the scuffing resistance excellent.

In this metal sintered body, the area ratio of spherical carbides with an average grain size of 10 μm or less in the structure is 10 to 40%.
The reason why the particles are uniformly dispersed within this range is that if the average particle size exceeds 10 μm, the damage to the sliding mating material increases.

Moreover, the reason why the carbide shape is spherical is that damage to the mating material on which it slides can be reduced.

Furthermore, if the area ratio of carbides in the structure exceeds 40%, the amount of carbides becomes excessive and increases damage to the sliding mating material, while if it is less than 10%, the amount of carbides is too small and reduces wear resistance. Therefore, it is preferably 10 to 40%.

[Example] The present invention will be explained below with reference to Examples.

l”e2Q3 powder, M003 powder, N with a particle size of 5 μm or less
iO powder, Cr t O3 powder, WO3 powder, VtOs
The powder, NbzOs powder, and C powder were mixed so that each sample composition shown in Table 1 was obtained after i addition, and mixed for 10 hours in hexane as a solvent using a ball mill.

Next, the mixed powder of fine metal oxide powder blended as described above was dried and passed through a 100-mesh sieve, and the mixed powder was incubated at 1000°C for 2 hours in an ammonia decomposition gas with a dew point of 40'C. Based on this, various compositions of spongy alloys as shown in Table 1 were manufactured.

Next, this spongy alloy was crushed using a crusher to give 100%
After passing through a mesh sieve, the finely crushed alloy powder was used as it was and compacted at a pressure of 5 tons/cn2, and then heated for 11 hours in ammonia decomposition gas with a dew point of 40°C.
Sintering was performed at 20° C. for 1 hour.

In Table 1, Example No. 1 Mo: 20%, Ni
: 5%, Cr: 8%, W: 2%, C: 1° 8%, and the remainder substantially consists of Fe, Fezo3 powder with a particle size of 5 μm or less:: 90g, MOO3 Powder: 309, NiO powder = 10g, Cr103 powder = 1
2g of C powder (graphite) and 19.4G of C powder (graphite) were blended and manufactured according to the above process.

In Example No. 2, NbzOs powder was added in place of the WO3 powder in Example No. 1, and other fine metal oxide powders were blended in the composition shown in Table 1.

It was formed by reduction in the same manner as 1. This thing is N
Contains 0.7% of b.

Example No. 34. t, Example No. 0.1 (7) VtOs powder was added in place of WO2 powder, and other fine metal oxide powders were blended in the composition shown in Table 1.

It was reduced, molded, and sintered in the same manner as 1. This material contains 1% V.

In Example No. 1, NbtO5 powder and VtOs powder were added in place of the WO2 powder in Example No. 1, and other fine metal oxide powders were blended in the composition shown in Table 1.
It is reduced, molded and sintered in the same manner as . This material contains 0.2% Nb and 1.5% ■.

In Example No. 065, Nb2O5 powder was added in addition to the WO2 powder of Example No. 1, and other fine metal oxide powders were blended in the composition shown in Table 1.

It was reduced, molded, and sintered in the same manner as 1. This material contains 4% W and 0.1% Nb.

Comparative example No. 001 did not add Ni and the MO content was 10%.
Less than 5%, Cr less than 3% and 2% Nb 0.2%
This is a case where the area ratio of carbide in the sintered body added to 1q is less than 10%.

Comparative example N002 contains 4% or more of C, 20% or more of Or,
The average grain size of the carbide in the sintered body containing 3% or more of (2) is 10 μm or more, and the area ratio is 40% or more.

Comparative Example No. 3 has a density ratio of less than 98%, an average residual pore diameter of 5 μ or more, and a W peak of 5% or more.

Comparative example No. 094 is C, Cr, and MC of the prior art.

It is a sintered alloy consisting of Co (cobalt) and the remainder Fe.

After the above sintered body was brazed onto a rocker arm, it was processed and finished into the shape of a rocker arm pad, and as shown in FIG. 1, it was assembled into an internal combustion engine and subjected to a bench durability test.

In FIG. 1, reference numeral 1 denotes a swing arm type rocker arm, and the rocker arm main body 1a, including the part that contacts the valve 2 and the lash adjuster 3, is made of steel or alloy like the conventional rocker arm. On the other hand, the portion 1lIlvJ, that is, the rocker arm pad portion 1b, is formed of the sintered alloy as described above.

The rocker arm pad portion 1b made of a sintered alloy may be fixed to the rocker arm main body portion 1a by any means, such as brazing, mechanical caulking, casting, or the like.

Note that in this example, a brazing method was used.

The opening properties of the sintered body [hardness (HV), density ratio (%),
Table 1 shows the measurement results of the average residual pore diameter (μ), structure (carbide particle size, carbide area ratio)], and the measurement results of the amount of wear on the rocker arm pad portion 1b and the amount of cam wear at the end of this bench durability test. Shown below.

In all of the Examples, the cam wear ■ (amount of wear on the mating member) is smaller than that of the Comparative Examples. The amount of pad wear (wear ff1 of the member of the present invention) is almost the same as that of Comparative Examples No. 2 and 2, in which large amounts of V and Cr are added, and the overall level is improved.

Furthermore, it is shown that when Or is used instead of Comparative Example No. 014, the damage to the mating member (cam wear amount) is inferior to that of this example.

[Effect of the invention] During the metal sintering of the valve train member of the internal combustion engine according to the present invention,
A mixture of fine metal oxides containing each metal element is reduced with graphite powder to achieve the reduced composition, and the resulting alloy powder is shaped and sintered to provide excellent wear resistance and scuffing resistance. Moreover, it can be applied to a sliding mating member (cam member), for example, a valve lifter, and depending on the type and type of valve train member, it can be applied not only to the part that contacts the cam but also to other parts.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a valve mechanism of an internal combustion engine. 1...Rocker arm 1a...Rocker arm main body 1b...Rocker arm pad part 2...Valve 3...Lash adjuster 4...cam

Claims (3)

[Claims] (1) Composition after reduction: C (carbon): 1 to 4% by weight
, Mo (molybdenum): 10-40%, Cr (chromium)
: 3 to 20%, Ni (nickel): 1 to 10%, and Nb (niobium): 0.05 to 1%, W (tungsten)
: 0.3 to 5%, V (vanadium): 0.1 to 3%, the balance is substantially Fe (iron), and the fine metal oxide contains each of the above metal elements. 1. A valve train member for an internal combustion engine, characterized in that it is a metal sintered body formed by molding and sintering an alloy powder produced by mixing and reducing graphite powder into a mixed powder containing a compound powder. (2) The metal sintered body has a density ratio of 98% or more and a diameter of 5
A valve train member for an internal combustion engine according to claim 1, wherein substantially spherical closed pores of μm or less are uniformly distributed. (3) The internal combustion according to claim 1, wherein the metal sintered body has spherical carbides having an average particle size of 10 μm or less and uniformly dispersed in an area ratio of 10 to 40% in the structure. Engine valve train components.