JPH04263037A - Engine and structural member for vehicle - Google Patents

Abstract

PURPOSE: To provide a structural member for engine which is low in density and friction and excellent in heat resistance and wear resistance by allowing the fine layer-shaped eutectic magnesium silicide and lump-shaped magnesium silicide to be present in the matrix of the magnesium casting.

CONSTITUTION: A structural member for an engine and a vehicle is obtained from magnesium or its alloy through the low pressure casting, the die casting, the pressure casting, etc. Fine layer-shaped eutectic magnesium silicide 7 and primarily separated lump-shaped magnesium silicide 6 are present in the matrix. The quantity of the magnesium silicide is 1-50 mass %, preferably, 3-50%. In the structure, ≤12% Al or Zn, ≤16% Ag, ≤1% Zr or Ti, ≤7% rare earth metal, ≤1% one or more kinds of Mn, Cu, Co, Ni and Cr, can be added as necessary. The ceramic fiber such as Al₂O₃ and SiC may be present in the matrix as the formed body.

COPYRIGHT: (C)1992,JPO

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to structural members for engines and vehicles manufactured from magnesium or magnesium alloys by low pressure casting, die casting or pressure casting, particularly pistons, cylinders, cylinder heads for internal combustion engines or compressors, This invention relates to structural members used in cylinder blocks and gear housings.

0002

BACKGROUND OF THE INVENTION The goal of fuel-efficient, quiet, and low-vibration engines and vehicles has resulted in high demands on the structural components that constitute them. In order to achieve this goal, it is important to reduce the mass of structural members that will be put into practical use. This is because this reduction provides a broader secondary weight reduction to the engine and vehicle, and in addition to this weight reduction, provides a larger fuel consumption savings. And said reduction in mass of structural members results in lower vibrations in the engine,
This not only promotes more effective noise suppression, but also results in even greater comfort.

In the piston described above, in addition to a reduction in the compression height of the piston, for example, which results in a clear reduction in the piston mass in the piston pin boss, ring groove and piston head, and a reduction in the height of the piston skirt, the relative In internal combustion engines, there has always been an attempt to use magnesium or magnesium alloys as piston materials in order to reduce the vibrating mass and bearing loads of internal combustion engines caused by the lighter weight of the pistons. Was.

[0004] However, magnesium materials have significant drawbacks when compared to aluminum-silicon alloys that are commonly used in the manufacture of light metal pistons for internal combustion engines. In other words, the service life of a piston made of magnesium material is shortened in proportion to the mixed wear that occurs during start-up, steady-state and emergency operation of the driven engine due to the lack of wear resistance. Also, its strength is relatively low against dynamic stresses caused by gas pressure.

[0005] In order to improve the above wear resistance, DE-20
No. 46 862, the sliding surface of a piston made of magnesium material is covered with a wear-resistant metal layer, for example chromium. Note that this metal layer is fixed to the piston body via an intermediate layer made of aluminum.

[0006] Furthermore, aluminum alloy, iron,
It is also known to provide coatings of wear-resistant materials consisting of graphite, manganese, nickel, tin, lead, cadmium or zinc, or to alloy magnesium with wear-resistant elements such as aluminum or silicon.

[0007] To further improve the strength, magnesium is alloyed with cerium and thorium, and the piston is forged so that the grains are oriented in a fibrous manner (as reported by the company journals Mahle Car Game and Electron). −
K. M. B. Har, Sututtgart-Bad Kanstutt, 1946 (Firmenschri)
ft MahleKG and Electron-C
o. mbH, Stuttgart-Bad Can
Nstadt, 1946).

[0008]

[Problem to be Solved by the Invention] However, all of the above-mentioned measures do not provide a functional piston for internal combustion engines.
Production from magnesium materials has hitherto been insufficient. It is true that JP-63-042338A discloses a piston for an internal combustion engine made of a magnesium alloy and reinforced with 3 to 30% by volume aluminum oxide-silicon oxide fiber, but this type of light metal piston is It has not been put into practical use so far. This is because pistons of this type cause relatively high wear on the cylinder sliding surfaces.

[0009] It is thus an object of the present invention to provide an engine or vehicle engine which satisfies high strength requirements against dynamic stresses, particularly when used in internal combustion engines, and which meets the strength requirements with very high special results. An object of the present invention is to provide a magnesium or magnesium cast structural member.

0010

[Means for Solving the Problem] This problem is achieved by using the above-mentioned material, which contains hard fine layered eutectic magnesium silicide and primary separated bulk magnesium silicide in a heat-resistant and ductile matrix. This is solved by a structural member consisting of Such structural members have a relatively low mass compared to conventional aluminum-silicon alloy cast structural members, and at the same time have sufficient heat resistance, wear resistance, and relatively low friction. be.

When magnesium silicide or silicon is added to a magnesium or magnesium alloy melt, a separation of finely layered eutectic magnesium silicide and primary separated bulk magnesium silicide is obtained during solidification. This gives the structural member good strength properties at high temperatures. In particular, it improves fatigue strength at high temperatures.

When 0.25 to 7.0% by weight of magnesium silicide or 0.1 to 2.5% by weight of silicon is added to magnesium or a magnesium melt, it is aligned with the magnesium in the form of a finely layered eutectic. A structure containing predominantly magnesium silicide and resulting in a network structure of eutectic magnesium silicide yields a remarkable high-temperature strength (cohesive strength) of the structural member.

[0013] Furthermore, when more than 3.6% by mass of magnesium silicide or more than 1.3% by mass of silicon is added to a magnesium or magnesium alloy melt, primary separated lump-like magnesium silicide and magnesium/magnesium silicide A structure consisting of a eutectic and essentially contributing to improvement of high-temperature strength is obtained.

[0014] In a special embodiment of the invention, the matrix of the structural member comprises 1 to 50% by weight (excluding 1).
, preferably 3 to 50% by weight of magnesium silicide.

The magnesium or magnesium alloy cast structural member contains all magnesium silicide in eutectic and primary form. That is, silicon, especially 0.
It is contained in a concentration range of 3 to 18% by mass (excluding 3).

Magnesium alloys of particular interest include 6-9% aluminum, 0.13% manganese, 0.
．． Consisting of 68-0.7% zinc, remainder magnesium,
Or 3.5% rare earth, 5.25% yttrium, 0
．． Consists of 5% zirconium, balance magnesium.

[0017] Within the scope of the invention, the matrix of the structural component contains up to 12% by weight of aluminum and/or zinc. Furthermore, this aluminum and zinc are
Separation has the effect of increasing piston strength.

The above-mentioned increase in strength, especially high-temperature strength, occurs with the addition of up to 16% by weight of silver.

[0019] In order to getter dissolved hydrogen, the matrix of the structural element can further contain up to 1% by weight of zirconium and/or titanium. Note that this zirconium or titanium additionally has the effect of refining crystal grains.

The addition of up to 7% by weight of one or more rare earth metals improves the creep strength. In addition, the specific gravity of the magnesium material is particularly reduced by adding up to 7% by mass of lithium.

In the present invention, age hardening of cast structural members is promoted by the addition of up to 1% by weight of one or more of the metals manganese, copper, gobalt, nickel and chromium.

Ceramic fibers, in particular aluminum oxide, silicon carbide, carbon, aluminum nitride or silicon nitride fibers, can be incorporated into the matrix of the structural component. In this way, the fibrous molding is prepared in an expedient manner.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a cross-sectional view of a piston for an internal combustion engine taken along a plane including a piston shaft and a piston pin shaft. This piston is a magnesium cast piston,
Piston head part 1 with combustion recess 2, ring groove part 3
and a skirt portion provided with a piston pin hole 5.

[0025] A part of the piston (X part in Fig. 1) is
In the microscopic structure photograph shown in Fig. 2, which is magnified twice, the volume is approximately 50% of the primary separated lump-like magnesium silicide 6.
is observed and its color is dark gray. Note that this block-like magnesium silicide 6 has fine layered eutectic magnesium silicide therein and is surrounded by magnesium 7 having a light gray color.

The above material has the properties shown in Table 1. For comparison, the table also shows the characteristics of a common aluminum alloy for pistons, that is, an AlSi12CuNiMg alloy.

[0027]

[Effects of the Invention] Since the present invention has the above-mentioned configuration,
Common aluminum-silicon alloys for piston manufacturing;
When compared with the structural member of the present invention, the structural member of the present invention has its density reduced by at least a full 30%, yet still retains a sufficiently high heat resistance similar to the prior art. .

[Brief explanation of the drawing]

[Figure 1] Cross-sectional view of a piston for an internal combustion engine

[Figure 2] Microscopic organization diagram within the X region of Figure 1

[Explanation of symbols]

6 Blocked magnesium silicide

Claims (9)

[Claims] Claim 1: Structural members for engines and vehicles manufactured from magnesium or magnesium alloys by low pressure casting, die casting or pressure casting, particularly pistons, cylinders, cylinder heads, cinder blocks and gear housings for internal combustion engines or compressors. A structural member for engines and vehicles in which fine layered eutectic magnesium silicide 7 and primary separated bulk magnesium silicide 6 are present in a matrix. [Claim 2] 1 to 50% by mass (1
2. Structural component according to claim 1, wherein magnesium silicide is present in an amount of 3 to 50% by weight. 3. Structural component according to claim 1, in which up to 12% by weight of aluminum and/or zinc is added. Claim 4: Claim 1 in which up to 16% by mass of silver is added.
, 2 or 3. 5. Structural element according to claim 1, in which up to 1% by weight of zirconium and/or titanium is added. 6. Structural component according to claim 1, 2, 3, 4 or 5, to which up to 7% by weight of rare earth metals are added. 7. A structural member according to claim 1, wherein up to 1% by weight of one or more of the metals manganese, copper, cobalt, nickel and chromium is added. 8. Structure according to claim 1, 2, 3, 4, 5 or 6, wherein ceramic fibers, in particular ceramic fibers consisting of aluminum oxide, silicon carbide, carbon, aluminum nitride or silicon nitride, are present in the matrix. Element. 9. A structural member according to claim 8, wherein said fibers are present within said matrix as shaped bodies.