JPH02243732A - Valve made of composite material for internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the wear resistance of the face part of a valve and to increase the output of an internal-combustion engine by reinforcing the face part of the valve with a prescribed volume percentage of silicon carbide whiskers and chromium carbide particles in combination. CONSTITUTION:A valve 56 for an internal-combustion engine is formed with composite materials each using a light metal as the matrix. The face part 62 of the valve 56 is made of a composite material 64 which is a light alloy reinforced with 20-40vol.%, in total, of silicon carbide whiskers 30 and chromium carbide particles 32 in combination. The wear resistance of the face part 62 of the valve 56 is improved and the output of an internal-combustion engine using the valve 56 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to valves for internal combustion engines, and more particularly to valves for internal combustion engines made of composite materials.

Conventional Technology In order to reduce the weight of valves incorporated into internal combustion engines, attempts have been made to form valves from composite materials made of light metals reinforced with reinforcing materials. For example, as one of the engine valves,
As described in Japanese Patent No. 1-143535, a valve for an internal combustion engine made of an aluminum alloy compositely reinforced with silicon carbide whiskers having a volume fraction of 15 to 35% has been known. According to such a valve for an internal combustion engine, the inertial mass can be reduced compared to a conventional valve made of steel, and the durability and heat resistance can be improved compared to a valve made only of an aluminum alloy. .

Problems to be Solved by the Invention However, with the increase in output and rotation speed of internal combustion engines in recent years,
The temperature around the valve tends to be higher than before, and the valve is exposed to a harsher thermal environment than before, so as mentioned above, carbonization with a volume ratio of 15 to 35% Aluminum alloys compositely strengthened with silicon whiskers alone cannot ensure sufficient wear resistance on the valve face, and therefore, depending on the valve, it is not possible to sufficiently increase the output and rotation speed of an internal combustion engine. cannot be achieved.

In consideration of conventional valves for internal combustion engines made of aluminum alloys compositely reinforced with silicon carbide whiskers with a volume fraction of 15 to 35%, the present invention has excellent wear resistance of the valve face, and therefore improves the output of internal combustion engines. The purpose of the present invention is to provide a valve for an internal combustion engine made of a composite material that enables the achievement of high engine speeds and high engine speeds.

Means for Solving the Problems According to the present invention, the above-mentioned objects are as follows: (1) A valve for an internal combustion engine made of a composite material having a matrix of light metal, in which the valve face portion is made of a mixture of silicon carbide whiskers and chromium carbide particles. The total volume fraction of silicon carbide whiskers and chromium carbide particles is 20
A valve for an internal combustion engine characterized by ~40%, ■
In an internal combustion engine valve made of a composite material with a light metal matrix, the valve face is made of a light metal reinforced with a mixture of silicon carbide whiskers and Ni particles, and the total volume fraction of the silicon carbide whiskers and Ni particles is 1
0 to 40%; and (1) an internal combustion engine valve made of a composite material with a light metal matrix, in which the valve face is made of a mixture of silicon carbide whiskers and potassium titanate whiskers. By a valve for an internal combustion engine made of a reinforced light metal, characterized in that the total volume fraction of silicon carbide whiskers and potassium titanate whiskers is 20 to 40%, and the volume fraction of silicon carbide whiskers is 8% or more. achieved.

Effects and Effects of the Invention According to the above configuration, the total volume ratio is 20 to 40%.
silicon carbide whiskers and chromium carbide particles with a total volume fraction of 10 to 40% and N
It is clear from the results of experimental research later conducted by the inventors that the valve face is compositely strengthened by i-particles or by silicon carbide whiskers and potassium titanate whiskers with a total volume fraction of 20 to 40%. As such, the wear resistance of the valve face can be greatly improved compared to the case where the valve face is made of an aluminum alloy compositely reinforced with only silicon carbide whiskers.
Thereby, it is possible to achieve higher output and higher rotation speed of the internal combustion engine.

According to one detailed feature of the present invention, in the above configuration (1), the total volume fraction of silicon carbide whiskers and chromium carbide particles is set to 30 to 40%.

According to another detailed feature of the present invention, the above-mentioned
In the configuration, the total volume fraction Va of silicon carbide whiskers and chromium carbide particles is set to 30 to 40%, and the volume fraction VS of silicon carbide whiskers is 5% or more and (Va-5)%.
It is set as below.

According to another detailed feature of the present invention, the above-mentioned
In this configuration, the total volume fraction of silicon carbide whiskers and Ni particles is set to 20 to 40%.

According to still another detailed feature of the present invention, in the above-mentioned configuration (2), the total volume fraction vb of silicon carbide whiskers and Ni particles is set to 20 to 40%, and The volume fraction VS is set to (Vb-0,5)% or less.

According to yet another detailed feature of the present invention, in the above-mentioned structure (1), the total volume fraction of silicon carbide whiskers and potassium titanate whiskers is set to 30 to 40%.

According to yet another detailed feature of the present invention, in the configuration (2) above, the total volume fraction Vc of silicon carbide whiskers and potassium titanate whiskers is set to 30 to 40%, and the silicon carbide whiskers The volume fraction Vs of is 9% or more (
Vc-5)% or less.

The average fiber diameter of silicon carbide whiskers in the present invention is 0.
．． 1~0.5μm, average fiber length 20~200μm
m, the average particle size of the chromium carbide particles and Ni particles may be 3 to 45 μm, the average fiber diameter of the potassium titanate whiskers is 0.1 to 0.3 μm, and the average fiber length is 20 to 45 μm. It may be 30 μm.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

Example IA Silicon carbide whiskers (manufactured by Tokai Carbon Co., Ltd.) with an average fiber diameter of 0.48 m and an average fiber length of 30 μm and an average particle diameter of 30
By mixing micron chromium carbide powder (manufactured by Showa Denko K.K.) at various ratios and molding the mixture, silicon carbide whiskers 10 and chromium carbide particles 12 are formed as shown in FIG. 23 molded bodies 14 having dimensions of 80 x 80 x 20 mm were formed. In this case, the volume fraction Vs of silicon carbide whiskers, the volume fraction Vr of chromium carbide particles, and the total volume fraction Va of these were as shown in Table 1 below.

Next, after preheating each molded body to 600°C, it is placed in the mold cavity 20 of the mold 18 of the high-pressure casting apparatus 16 as shown in FIG. %Cus 1%St
, the remainder is substantially AI), and a plunger 24 that fits the molten metal into the mold is used to produce 1000 kg/♂
The pressurized state was maintained until the molten metal completely solidified. Next, parts reinforced with silicon carbide whiskers and chromium carbide particles are cut out from the thus obtained solidified body, and each composite material is subjected to solution treatment by heating to 580°C for 8 hours and artificial aging by heating to 180°C for 6 hours. Processed.

Block specimens for wear testing were then formed from each of the thus treated composite materials. However, a composite material in which the total volume fraction of silicon carbide whiskers and chromium carbide particles was 50% had extremely low toughness, and it was not possible to form a block test piece from them by machining. Next, each block test piece was sequentially set in an abrasion tester, and the sintered metal (0.9% C, 5% Mo, 2.5% C01
The outer peripheral surface of a cylindrical specimen made of 16% Pb, the remainder being substantially Fe) was brought into contact in a dry, non-lubricated state, and a contact load of 12.6 k was applied.
g, sliding speed 0. 94 m/see, sliding distance 10
An Okoshi type abrasion test was conducted in which a cylindrical test piece was rotated at a distance of 0 m. The results of these wear tests are shown in FIGS. 3 to 6.

In the inner cylinders 3 to 6, the dashed lines and dashed-dotted lines are for comparison reference, respectively, and are reinforced with silicon carbide whiskers with a volume ratio of 35% and are the same as the aluminum alloy used in this example. Composite material A with an aluminum alloy as a matrix and Ni-Cr alloy B, which is commonly used as a filler metal for the valve face of internal combustion engine valves.
shows the amount of wear (area of wear scars).

From these graphs, it can be seen that a composite material using silicon carbide whiskers and chromium carbide particles as a reinforcing material has better wear resistance than a composite material using only either of these as a reinforcing material. In addition, a composite material in which the total volume fraction Va of silicon carbide whiskers and chromium carbide particles is 20 to 40% has better wear resistance than the comparative reference composite material A. The total volume fraction Va is preferably 20 to 40%, particularly 30%.
It turns out that it is preferable that it is 40%.

Further, when the total volume fraction Va is 20%, the volume fraction Vs of silicon carbide whiskers is preferably 15% or less, and especially when the total volume fraction Va is 30 to 40%, the silicon carbide whisker The volume ratio of whiskers is 5% or more (V a
-5)% or less, the wear resistance of the composite material is Ni-C
It can be seen that it is equivalent to or better than r alloy.

The same results as those shown in Figures 3 to 6 were obtained in a wear test similar to the above wear test except that an aluminum alloy (JIS standard AC8A) was used as the matrix metal. Ta.

Example IB Silicon carbide whiskers (manufactured by Tokai Carbon Co., Ltd.) with an average fiber diameter of 0.5 μm and an average fiber length of 30 μm were suction molded and machined to form a carbonized product with a volume ratio of 25% as shown in FIG. A molded body 28 for a valve body made of silicon whiskers 26 was formed. In addition, the average fiber diameter is 0.5 μm,
A mixture of silicon carbide whiskers (manufactured by Tokai Carbon Co., Ltd.) with an average fiber length of 30 μl and chromium carbide powder (manufactured by Showa Denko Co., Ltd.) with a particle size of 30 μl was vacuum-molded and then machined to form the material shown in Figure 8. As shown, the volume fraction 2
A molded body 34 for a valve face portion was formed from a mixture of 0% silicon carbide whiskers 30 and 20% volume fraction chromium carbide particles 32.

Next, as shown in Figure 9, stainless steel (JI
A cylindrical case 36 made of S standard 5US304) having an air chamber 40 at one end that communicates with the inside of the case through a communication hole 38 is prepared, and a valve body molding is placed inside the case as shown in the figure. The body 28 and the molded body 34 for the valve face portion were arranged in a mutually assembled state, and a round bar 42 for preventing the molded body from floating was fixed to the inner surface of the case by welding.

Next, after preheating the two molded bodies to 600°C in each case,
As shown in FIG. 10, two molded bodies are placed in each case in a mold cavity 48 of a mold 46 of a high-pressure casting device 44.
A molten metal 50 of 4% Cu, 1% Si1 and the balance substantially AI) is poured, and the molten metal is pumped with a plunger 52 to a weight of approximately 1000 kg.
/anl! The pressurized state was maintained until the molten metal completely solidified.

After the molten metal has completely solidified, the solidified body is removed from the mold using the knockout pin 54, and the solidified body is machined to take out the cylindrical body formed inside the case 36. By performing solution treatment by heating to 180°C for 8 hours, artificial aging treatment by heating to 180°C for 6 hours, and further performing mechanical pre-processing, an intake valve 56 for an internal combustion engine as shown in FIG. 11 is manufactured. Formed. In FIG. 11, 58 and 60 respectively indicate the valve stem and the valve part, and the valve face part 62 of the valve part.
is a silicon carbide whisker with a volume fraction of 20% and a volume fraction of 20%
The aluminum alloy composite material 64 was reinforced with chromium carbide particles.

The intake valve thus formed was then adjusted to a displacement of 1600
A durability test was conducted in which the test piece was installed in a cc four-cylinder gasoline engine and the engine was operated for 100 hours at a rotational speed of 6000 rpv and a full load of 1:1. Also, for comparison purposes, the entire valve is made of an aluminum alloy composite reinforced with silicon carbide whiskers, the silicon carbide whiskers and aluminum alloy are the same as those used in this example, and the volume fraction of silicon carbide whiskers is A similar test was also conducted on a valve (hereinafter referred to as a valve of a comparative example) in which the intake air pressure was 35%.

As a result of these tests, the amount of wear (wear depth) on the knob face portion of the valve of the comparative example was 67 μm, while the amount of wear on the knob face portion of the valve of this example was 10 μm. Therefore, it can be seen that the durability of the valve of this example is far superior to that of the valve of the comparative example.

Example IC Made of alumina short fibers ("Safil" manufactured by IC1) with an average fiber diameter of 3 μm and an average fiber length of 3 mm, and a fiber volume percentage of 30
%, the volume fractions of silicon carbide whiskers and chromium carbide particles in the valve face molded body were set to 10% and 30%, respectively, and a magnesium alloy (690°C) was formed as the matrix molten metal. J.I.
The intake knob was formed in the same manner and under the same conditions as in Example IB above, except that S standard MDCI-A) was used and no heat treatment was applied to the composite material. A durability test was conducted under the same conditions as in the case of . As a result, the amount of wear (wear depth) in the 71 Leboeuf area of the valve of this example was 12 μm, and the durability of the valve of this example was also far superior to the /<Lube of the comparative example. was recognized.

Example 2A Pure Ni particles (with an average particle size of 5 μm) were used instead of chromium carbide powder.
(manufactured by Rare Metallic Co., Ltd.) was used, and the volume fraction of silicon carbide whiskers, the volume fraction of SNi particles, Vn, and the total volume fraction of these, Vb, were set to the values shown in Table 2 below,
Composite materials were manufactured in the same manner and conditions as in Example IA above, except that the preheating temperature of the molded body was set at 400°C, and each composite material was manufactured in the same manner as in Example IA. A wear test was conducted under the following conditions. The results of these wear tests are shown in FIGS. 12 to 15.

In this case, the total volume fraction of silicon carbide whiskers and Ni particles is 40%, and the composite material in which the volume fraction of Ni particles is 4% or more, and the total volume fraction of silicon carbide whiskers and Ni particles is 50%. Regarding composite materials, cracks occurred when machining block specimens from these composite materials, so it was not possible to perform wear tests.

From the graphs shown in FIGS. 12 to 15, it can be seen that, except when the total volume fraction vb of silicon carbide whiskers and Ni particles is 10%, the composite material using silicon carbide whiskers and Ni particles as a reinforcing material is It can be seen that this material has better wear resistance than a composite material that only uses silicon whiskers as a reinforcing material. Further, the total volume fraction vb of silicon carbide whiskers and Ni particles is 10%, and the volume fraction of silicon carbide whiskers is 7.
Composite materials in which the volume fraction of silicon carbide whiskers and Ni particles is 5% or more and composite materials in which the total volume fraction of silicon carbide whiskers and Ni particles is 20 to 40% have better wear resistance than the comparative reference composite material A. It can be seen that the total volume fraction of whiskers and Ni particles is preferably 20 to 40%. In addition, when the total volume fraction vb is 20 to 40%, and the volume fraction Vs of silicon carbide whiskers is (Vb-0,5) or less, the wear resistance of the composite material is equal to or equal to that of Ni-Cr alloy. From the above, it can be seen that especially when the total volume fraction vb is 40%, it is preferable that the volume fraction Vn of the Ni particles is 3% or less.

The same results as those shown in FIGS. 12 to 15 were obtained in a wear test similar to the above wear test except that an aluminum alloy (JIS standard AC8A) was used as the matrix metal. Ta.

Example 2B A molded body for a valve face portion was formed from a mixture of silicon carbide whiskers with an average fiber diameter of 0.5 μm and average fiber length of 30 μm and Ni particles with an average particle size of 5 μm, and the volume ratio of the silicon carbide whiskers and Ni particles was are 20% and 3, respectively.
An intake valve was formed in the same manner and under the same conditions as in Example IB above, except for the point set at went.

As a result, the amount of wear on the valve face portion of the valve of this example was 9 μm, and it was confirmed that the durability of the valve of this example was also far superior to that of the valve of the comparative example.

Example 2C Made of short alumina fibers ("Safil" manufactured by IC1) with an average fiber diameter of 3 μm and an average fiber length of 3 mm, and a fiber volume percentage of 25
%, the volume fraction of silicon carbide whiskers and Ni particles in the valve face molded body were set to 25% and 1%, respectively, and the molten metal of the matrix was formed using a magnesium alloy (JIS Standard M
The intake valve was formed in the same manner and under the same conditions as in Example 2B above, except that DCI-A) was used and no heat treatment was applied to the composite material, and the same as in Example IB. Durability tests were conducted under the following conditions.

As a result, the amount of wear (wear depth) on the valve face of the valve of this example was 11 μm, and it was confirmed that the durability of the valve of this example was also far superior to that of the valve of the comparative example.

Example 3A Potassium titanate whiskers (manufactured by Otsuka Chemical Co., Ltd.) with an average fiber diameter O of 12 μm and an average fiber length of 30 μm were used instead of chromium carbide powder, and the volume ratio of silicon carbide whiskers was V.
Same procedures and conditions as in Example IA above, except that the volume fraction Vt1 of potassium titanate s, the volume fraction Vt1 of the Wiss force of potassium titanate, and the volume fraction Vc of these totals were set to the values shown in Table 3 below. Composite materials were manufactured in the same manner as in Example IA, and each composite material was subjected to an abrasion test under the same procedure and conditions as in Example IA. The results of these wear tests are shown in FIGS. 16 to 18.

In this case, for composite materials in which the total volume fraction of silicon carbide whiskers and potassium titanate whiskers is 50%, cracks occur when forming professional test specimens from these composite materials by machining. It was not possible to perform a wear test.

From the graphs shown in FIGS. 16 to 18, it can be seen that the composite material containing silicon carbide whiskers and potassium titanate whiskers as a reinforcing material has better wear resistance than the composite material containing only silicon carbide whiskers or potassium titanate whiskers as a reinforcing material. It turns out that they are good at sex. In addition, the total volume fraction Vc of silicon carbide whiskers and potassium titanate whiskers is 20 to 4.
The composite material has a silicon carbide whisker volume fraction Vs of 0%.
is 9% or more, the wear resistance is superior to the comparative reference composite material A, especially when the total volume fraction Vc of silicon carbide whiskers and potassium titanate whiskers is 30 to 4.
0%, the composite material has a volume fraction of silicon carbide whiskers of 8
% or more, it can be seen that the wear resistance is superior to that of the comparative reference composite material A. In addition, when the total volume fraction Vc is 30 to 40%, and the volume fraction Vs of silicon carbide whiskers is 9% or more and (V c -5)% or less, the wear resistance of the composite material is that of the Ni-Cr alloy. It can be seen that it is equal to or higher than.

In addition, the same results as shown in FIGS. 16 to 18 were obtained in a wear test similar to the above wear test except that an aluminum alloy (JIS standard AC8A) was used as the matrix metal. Ta.

Example 3B Silicon carbide whiskers with an average fiber diameter of 0.5 μl and an average fiber length of 30 μm and an average fiber diameter of 0.2 μm and an average fiber length of 30 μm.
m potassium titanate whisker (manufactured by Otsuka Chemical Co., Ltd.)
The molded body for the valve face portion was formed from a mixture consisting of the above, and the same as in Example 2B described above, except that the volume percentages of silicon carbide whiskers and potassium titanate whiskers were set to 25% and 10%, respectively. An intake valve was formed in the same manner and under the same conditions as Example I.
A durability test was conducted under the same procedure and conditions as in case B.

As a result, the amount of wear on the valve face portion of the valve of this example was 13 μm, and it was confirmed that the durability of the valve of this example was also far superior to that of the valve of the comparative example.

Example 3C Made of short alumina fibers ("Safil" manufactured by IC1) with an average fiber diameter of 3μ11 and an average fiber length of 3mm, and a fiber volume percentage of 30
%, the volume percentages of silicon carbide whiskers and potassium titanate whiskers in the valve face molded body were set to 10% and 30%, respectively, and the molten metal of matrix 2 was heated to 690°C. The intake knob was prepared in the same manner and under the same conditions as in Example 3B above, except that a magnesium alloy (JIs standard MD'CI-A) was used and no heat treatment was applied to the composite material. A durability test was conducted under the same conditions as in Example IB. As a result, the amount of wear on the valve face of the knob in this example (
The wear depth) was 15 μm, and it was confirmed that the durability of the valve of this example was also far superior to that of the valve of the comparative example.

Although the present invention has been described above in detail with reference to several embodiments, the present invention is not limited to these embodiments, and various other embodiments are possible within the scope of the present invention. It will be clear to those skilled in the art that

Table 1 Table 3 Vs (%) Vt (%) Table 2 9.5 19,5 29, 5 39,. 5 49,5

[Brief explanation of drawings]

Figure 1 is a perspective view showing a molded body made of silicon carbide whiskers and chromium carbide particles, Figure 2 is a sectional view showing a high-pressure casting process performed using the molded body shown in Figure 1, and Figure 3. Figures 6 to 6 show the results of wear tests on composite materials made of aluminum reinforced with silicon carbide whiskers and chromium carbide particles when the total volume fraction va of silicon carbide whiskers and chromium carbide particles is 10%, 20%, respectively. 30%,
Graph showing the case of 40%, Figure 7 is a perspective view showing a molded body for a valve body for manufacturing a valve for an internal combustion engine, and Figure 8 is a molded body for a valve face part for manufacturing a valve for an internal combustion engine. FIG. 9 is a sectional view showing the molded body shown in FIGS. 7 and 8 placed in the case, and FIG. 10 is a perspective view showing the assembly shown in FIG. 9. FIG. 11 is a cross-sectional view showing the high-pressure casting process to be carried out; FIG. Figures 1 to 15 show the results of wear tests conducted on composite materials made of aluminum alloys reinforced with silicon carbide whiskers and Ni particles, respectively, with the total volume fraction vb of silicon carbide whiskers and Ni particles.
The graphs shown in FIGS. 16 to 18 for cases where the The results of the wear test were determined when the total volume fraction Vc of silicon carbide whiskers and potassium titanate whiskers was 20%, 30%, and 4, respectively.
It is a graph shown about the case of 0%. DESCRIPTION OF SYMBOLS 10... Silicon carbide whisker, 12... Chromium carbide particle, 14... Molded object, 16... High pressure casting device, 1
8... Mold, 20... Mold cavity, 22...
... Molten aluminum alloy, 24... Plunger,
26... Silicon carbide whisker, 28... Molded body for valve body. 30... Silicon carbide whiskers, 32... Chromium carbide particles, 34... Molded body for valve face portion, 36...
・Case, 38...Communication hole, 40...Air chamber, 42.
··Round bar. 44... High pressure casting device, 46... Mold, 48...
Mold cavity, 50... Molten aluminum alloy 52... Plunger, 54... Knockout pin,
56... Valve, 58... Valve stem, 60...
Umbrella section 62... Valve face section patent applicant: Toyota Motor Corporation representative
Attorney Patent Attorney Ro Akishi
Tsuyoshi diagram Chromium carbide particle volume ratio Vr (%) Figure Chromium carbide particle volume ratio Vr (%) Figure Chromium carbide particle volume ratio Vr (%) Figure 11 Figure 12 13 14 16 17 Figure Silicon carbide whisker volume ratio Vs (%) Potassium titanate whisker volume ratio Vt (%) Figure 18 Figure Silicon carbide whisker volume ratio Vs (%)

Claims (3)

[Claims] (1) In an internal combustion engine valve made of a composite material with a light metal matrix, the valve face is made of a light metal reinforced with a mixture of silicon carbide whiskers and chromium carbide particles, and the valve face is made of a light metal reinforced with a mixture of silicon carbide whiskers and chromium carbide particles. A valve for an internal combustion engine, characterized in that the total volume fraction is 20 to 40%. (2) In an internal combustion engine valve made of a composite material with a light metal matrix, the valve face is made of a light metal reinforced with a mixture of silicon carbide whiskers and Ni particles, and the total amount of silicon carbide whiskers and Ni particles is A valve for an internal combustion engine, characterized in that the volume fraction is 10 to 40%. (3) In an internal combustion engine valve made of a composite material with a light metal matrix, the valve face is made of a light metal reinforced with a mixture of silicon carbide whiskers and potassium titanate whiskers, and the valve face is made of a light metal reinforced with a mixture of silicon carbide whiskers and potassium titanate whiskers. A valve for an internal combustion engine, characterized in that the total volume fraction of whiskers is 20 to 40%, and the volume fraction of silicon carbide whiskers is 8% or more.