JP2643680B2 - Valve seat made of metal-filled sintered alloy for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve seat made of a metal-filled sintered alloy for an internal combustion engine, which exhibits excellent wear resistance even under severe conditions and has a remarkably low aggressiveness to a counterpart.

[0002]

2. Description of the Related Art Conventionally, many other materials have been used as valve seats for internal combustion engines such as automobiles, for example, a copper infiltration sintered alloy described in Japanese Patent Application Laid-Open No. 58-178073.

[0003]

On the other hand, the speed and output of an internal combustion engine in recent years have been remarkable, and with this,
The use environment of the valve seat, which is a structural member of this, is also becoming more severe, but in conventional valve seats, those with excellent wear resistance have greater opponent aggression, while those with low It is inferior in abrasion resistance and does not have both of these characteristics. Therefore, at present, it does not exhibit sufficient performance for practical use under severe conditions.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoints, as a result of researching to develop a valve seat for an internal combustion engine which shows excellent wear resistance under severe use environment and has low aggressiveness to the other party, the valve seat is reduced by weight% ( Hereinafter,% relating to the composition ratio indicates weight%), and the micro Vickers hardness (MHv) is 700 to 1
Fe-Cr-Co-W-based alloy phase having 800 (hereinafter referred to as first phase): 3 to 15%, MHv: 500 to 1000
Co-Mo-Cr-based alloy phase having the following (hereinafter referred to as the second phase): 2 to 12%, and MHv: 100 to 300
e-Co-based alloy phase (hereinafter referred to as third phase): Cu or Cu alloy is infiltrated into a sintered alloy substrate having a residual three-phase mixed structure and a porosity of 5 to 20%. Or made of a copper infiltrated sintered alloy or a lead impregnated sintered alloy impregnated with Pb or a Pb alloy,
The research results show that the resulting valve seat made of a metal-filled sintered alloy shows excellent wear resistance even under practical use under severe conditions, and that the valve as a mating member has extremely small wear.

[0005] The present invention has been made based on the above research results, and the first phase of the Fe-Cr-Co-W alloy having MHv: 700 to 1800: 3 to 15
%, MHv: Co-Mo-C with 500-1000
Second phase of r-based alloy: 2 to 12%, MHv: 100 to 30
Cu or Cu alloy is infiltrated into a sintered alloy substrate having a three-phase mixed structure having a ratio of: a third phase of a Fe—Co-based alloy having 0 and a porosity of 5 to 20%. A valve seat made of a metal-filled sintered alloy for an internal combustion engine comprising a copper infiltrated sintered alloy or a lead impregnated sintered alloy impregnated with Pb or a Pb alloy.

[0006] In the valve seat of the present invention,
Fe-Cr-C of the first phase of the sintered alloy substrate constituting this
The oW alloys are: Co: 10 to 30%, W: 5 to 30%, Cr: 20 to 40%, Nb: 0.2 to 2%, Si: 0.2 to 2%, C: 1 to It is desirable that the Co-Mo-Cr-based alloy of the second phase contains: Mo: 20 to 40%; Cr: 5 to 15%; Si: 1 to 5%, the balance being Co and unavoidable impurities, and the third phase Fe—Co alloy is Co: 2 to 10%, Mo: 0.5 to 3%, Ni : 0.5 to 4%, C: 0.5 to 1.5%, and if necessary, Cr: 0.5 to 5%, Nb: 0.1 to 2% It is desirable to contain one or two of them, with the balance having the composition of Fe and inevitable impurities.

[0007] In the valve seat of the present invention,
The hardness and the content ratio of the first to third phases constituting the sintered alloy base are all empirically determined based on a large number of test results, and accordingly, the hardness and the content of each phase are determined. If any of the above is out of the above range,
When the overall hardness balance of the valve seat is lost and the hardness is relatively reduced or increased, the desired wear resistance may not be obtained, or the opponent aggression may increase. Therefore, by limiting the hardness and the content ratio of the first to third phases within the above ranges, it is possible to secure desired excellent wear resistance and small aggressiveness to a partner.

Further, the hardness of each of the first to third phases can be obtained by limiting the alloy composition constituting the first to third phases as described above, and the control of the hardness within the above range is performed by controlling the alloy composition. This is done by adjusting.

On the other hand, if the porosity is less than 5%, copper infiltration or lead impregnation becomes insufficient to obtain a desired strength, while if the porosity exceeds 20%, the wear resistance becomes poor. The porosity was determined to be 5 to 20% because it would be significantly reduced. Further, as the copper infiltration material, oxygen-free copper, C
Cu- having a composition of u-1 to 4% Co-1 to 2% Zn
Co-Zn alloy and Cu-2-5% Fe-1-6%
Cu-Fe-Mn- having a composition of Mn-1 to 4% Zn
It is preferable to use a Zn alloy, and as a lead impregnated material, pure P
b, It is desirable to use a Pb-30 to 40% Sn alloy.

[0010]

Next, the valve seat of the present invention will be described in detail with reference to examples. As the raw material powder, Table 1, Table 2,
And a particle size having the hardness and composition shown in Table 3: 1
Atomized powders of less than 00 mesh were prepared, and these raw material powders were blended in the composition shown in Tables 4 and 5; zinc stearate: 1% was added and mixed with a mixer for 30 minutes, and then 5-7 ton / cm ^The green compact is press-molded at a predetermined pressure in the range of ² , and the green compact is held at 500 ° C. for 30 minutes to degrease it.
Sintering is carried out at a predetermined temperature in the range of 100 to 1200 ° C. for one hour to obtain a composition having the same porosity as shown in Tables 4 and 5 and substantially the same as the composition. A sintered alloy substrate having a three-phase mixed structure was formed, and a portion of the sintered alloy substrate was made of pure Cu and Cu-2.4% Co-1. 3% Zn alloy (hereinafter referred to as Cu alloy 1) or Cu-3.6%
With the Fe-4.1% Mn-2.1% Zn alloy (hereinafter referred to as Cu alloy 2) mounted in a combination shown in Tables 4 and 5, the copper melt was held at a temperature of 1100 ° C. for 15 minutes. The copper infiltration sintered alloy is subjected to immersion to form a copper infiltration sintered alloy.
Heat treatment is performed at a predetermined temperature in the range of 00 to 700 ° C. for 1.5 hours, and the remaining sintered alloy substrate is
Pure Pb or Pb-35% heated to 600 ° C. in a nitrogen atmosphere with a pressure of 8 kg / cm ² applied to the bath surface
By performing lead impregnation under a condition of immersion and holding in a Sn alloy bath for one hour to obtain a lead-impregnated sintered alloy, each of them has an outer diameter of 3
The metal-filled valve seats 1 to 16 of the present invention and the comparative metal-filled sintered alloy valve seats 1 to 12 having dimensions of 4 mm × inner diameter: 27 mm × thickness: 7 mm were produced, respectively.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

[Table 5]

[0016] The comparative metal-filled sintered alloy valve seats 1 to 12 have any one of hardness, content ratio, and porosity of the first to third phases in the sintered alloy base constituting the valve seats. This is outside the scope of the present invention.

Next, regarding the various metal-filled valve seats obtained as a result, the material of the valve: JIS SUH36, the heating temperature of the valve: 850 to 900 ° C., the number of seating times of the valve: 3000 r. p. m. Atmosphere: Propane gas at a pressure of 0.4 kg / cm ² , combustion gas with oxygen at a flow rate of 1.6 l / min, Surface heating temperature of valve seat (internal water cooling): 350 to 4
A wear test was performed under the following conditions: 00 ° C. Test time: 100 hours, and the maximum wear depth of the valve seat and the maximum wear depth of the valve as the mating member were measured. Tables 4 and 5 show the measurement results.

[0018]

From the results shown in Tables 4 and 5, all of the metal-filled valve seats 1 to 16 of the present invention show excellent abrasion resistance and low aggressiveness on the other side, while the comparative metal As seen in the filled valve seat, the hardness and content ratio of the first to third phases constituting the sintered alloy substrate,
It is clear that, if any of the porosity is out of the range of the present invention, at least one of the abrasion resistance and the aggressiveness to the opponent becomes inferior.

As described above, the valve seat made of a metal-filled sintered alloy of the present invention has excellent wear resistance and remarkably low opponent aggressiveness, so that it can maintain excellent performance even in practical use under severe conditions for a long time. It is exerted over.

Claims (2)

(57) [Claims] 1. Micro Vickers hardness (MHv): 7
First phase of Fe-Cr-Co-W-based alloy having 00 to 1800: 3 to 15%, MHv: second phase of Co-Mo-Cr-based alloy having 500 to 1000: 2 to 12%, MHv: A third phase of a Fe-Co alloy having 100 to 300: a remaining (the weight%) three-phase mixed structure, and a sintered alloy substrate having a porosity of 5 to 20%;
A valve seat made of a metal-filled sintered alloy for an internal combustion engine, comprising a copper infiltrated sintered alloy obtained by infiltrating Cu or a Cu alloy. 2. Micro Vickers hardness (MHv): 7
First phase of Fe-Cr-Co-W-based alloy having 00 to 1800: 3 to 15%, MHv: second phase of Co-Mo-Cr-based alloy having 500 to 1000: 2 to 12%, MHv: A third phase of a Fe-Co alloy having 100 to 300: a remaining (the weight%) three-phase mixed structure, and a sintered alloy substrate having a porosity of 5 to 20%;
A valve seat made of metal-filled and bonded gold for an internal combustion engine, comprising a lead-impregnated sintered alloy impregnated with Pb or a Pb alloy.