JPS59229034A - Piston for internal-combustion engine - Google Patents

Abstract

PURPOSE:To check the diametrical expansion of a piston skirt shoulder part as well as to prevent its seizure or binding with a cylinder bore, by complexly strengthening a portion lying between an oil ring groove and a skirt part looking in the piston axial direction, with a bow-shaped reinforced fiber. CONSTITUTION:A portion lying between an oil ring groove 7 of a side wall 4 and a skirt part 12 looking in the direction of a piston axis 8 is complexly strengthened substantially with a bow-shaped reinforced fiber, for example, a silicon carbide whisker at both of a first range 14 vertically and linearly extending in a substantial manner to an axis 11 of a piston hole 10 and a second range 16 circularly extending along an outer circumferential surface 15 at the side of a piston from both ends of the said range 14. At the range 14, there is provided with a bent part 17 at which the skirt shoulder part bypasses the piston hole 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to internal combustion engines, and more particularly to pistons for internal combustion engines.

Pistons of internal combustion engines are generally made of aluminum alloy in order to reduce weight. Aluminum alloys have a large coefficient of thermal expansion, and the piston is essentially a hollow cylinder closed at the upper head, so it has a small heat capacity. The diameter expands as it is heated by the heat. Excessive expansion and expansion of the piston's diameter can cause problems such as seizure with the cylinder bore, so internal combustion engine pistons have traditionally been made of ring-shaped wire or plate-shaped steel, which has a smaller coefficient of thermal expansion than aluminum alloy. Struts are cast along a plane perpendicular to the axis of the piston, and these wires and struts 1- suppress expansion of the diameter of the piston, especially the shoulder of its skirt.

However, since steel has a higher specific gravity than aluminum alloy, it is difficult to improve the performance of an internal combustion engine because of the weight of the piston, which has steel wires and struts cast into it as described above. It is. In addition, as the performance of internal combustion engines increases, the maximum temperature of the piston tends to rise, and in such internal combustion engines, the steel wires and struts are also heated to a relatively high temperature and therefore expand relatively significantly. , it is difficult to effectively suppress the expansion and expansion of the diameter of the piston.

In view of the above-mentioned problems with conventional pistons for internal combustion engines in which steel wires and slats are cast, the present invention provides a piston for internal combustion engines that has been improved to avoid such problems. The purpose is to provide the following.

According to the present invention, the piston for an internal combustion engine is made of a light metal and has an oil ring groove, a skirt portion, and a piston pin hole. two regions whose portions between the skirt portion extend linearly substantially perpendicularly to the axis of the piston pin hole; and substantially along the side outer circular surface of the piston from both ends of the regions. This is achieved by a piston for an internal combustion engine which is compositely reinforced with reinforcing fibers in a substantially arcuate manner in a region extending in an arcuate manner.

According to the present invention, the portion between the oil ring groove and the skirt portion when viewed in the axial direction of the piston has two regions extending linearly substantially perpendicularly to the axis of the piston pin hole; Since the area extending substantially in an arc shape from both ends along the side outer circumferential surface of the piston is compositely reinforced with reinforcing fibers in a substantially arcuate manner, the screw F-n, especially its scar [ - Expansion of the diameter of the shoulder portion is effectively suppressed by the reinforced aHH, thereby reliably preventing problems such as seizure with the cylinder bore. Furthermore, according to the present invention, the reinforcing fibers used for composite reinforcement of the screw I/N may be fibers such as alumina fibers, which have a specific gravity lower than that of steel, and the matrix metal of the composite reinforcement may also be a piston. The other parts of the piston can be made of a light metal such as an aluminum alloy, which reduces the weight of the piston compared to conventional pistons with cast steel YA7 or struts, thereby reducing the weight of the piston. It is possible to improve the performance of

The reinforcing braid used in the present invention may be either long fibers (continuous fibers) or short fibers (discontinuous fibers), but in particular, it may be made of aluminum alloy or magnesium alloy that constitutes the bis. It is preferable to use short fibers such as alumina fiber, alumina-silica sM1 silicon carbide fiber, which has excellent properties and a small coefficient of thermal expansion, and voice fibers such as silicon carbide voice force and silicon nitride voice force. Although it varies depending on the fiber used, it is preferably about 10 to 50%.

In addition, the bis[.-n] according to the present invention is produced by forming a plate-shaped reinforcing fiber molded body with a reinforced m-thickness, placing the reinforcing fiber molding at a predetermined position in a mold for casting a piston, and placing it in the mold. Manufactured by a pressure casting method such as a high-pressure casting method in which molten metal such as aluminum alloy is poured, the molten metal is pressurized with an upper mold, and the molten metal is filled and infiltrated between the individual reinforcing fibers of the reinforced fiber molded product. In addition, struts made of a composite material made of a matrix metal and reinforcing materials oriented randomly in two dimensions or three dimensions are formed by high-pressure casting, etc., and the struts are placed in a predetermined position in a mold for piston casting. The strut may be manufactured by placing the strut in the mold, pouring a molten metal such as aluminum alloy into the mold, and casting the strut, but the former method is preferable from the viewpoint of improving productivity and reducing costs. .

The invention will now be described in detail with reference to embodiments, with reference to the accompanying drawings.

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the piston according to the present invention, FIG. 2 is a vertical cross-sectional view along the line ■-■ in FIG. 1, and FIG. 3 is a vertical cross-sectional view along the line ■-■ in FIG. FIG.

In these figures, 1 designates a head part, in which two combustion chamber recesses 2 and 3 are provided. Two compression ring grooves 5 and 6 and one oil ring groove 7 are provided on the outer circumferential surface of the substantially cylindrical side wall J of the piston along a plane perpendicular to the axis 8. Although not shown in the drawings, a compression ring and an oil ring are fitted into the groove 5.6 and the oil ring groove 7, respectively. Further, an oil drain @9 is provided on the side wall 4 to guide the oil scraped down by the oil ring into the inside of the piston.

A piston pin hole 10 is provided in the center of the piston, and the piston is connected to a crankshaft of an internal combustion engine by a piston pin and a connecting rod inserted through the piston pin hole 10, although not shown in the figure. It has become. Skirt portions 12 are provided at the end of the side wall 4 opposite to the head portion 1 on both sides of the axis 11 of the piston pin hole 10.

The illustrated piston is made of aluminum alloy, and in particular, the portion between the oil ring groove 7 of the side wall 4 and the skirt portion 12 when viewed in the direction of the axis 8 of the piston is relative to the axis 11 of the piston pin hole 10. two first regions 14 extending substantially perpendicularly in a straight line; and a second region extending substantially in an arc shape from both ends of the second region along the side outer circumferential surface 15 of the piston. Region 16 is compound reinforced with silicon carbide voice forces in a substantially arcuate manner. A curved portion 17 is provided in the first region 14 and bypasses the piston pin hole 10 at the curved portion. Although not shown in the figure, the silicon carbide voice force is applied to the first region 14 and the second region 16.
The particles are substantially randomly oriented and distributed in three dimensions.

A biscuit tube having the above-described structure was manufactured in the following manner. First, silicon carbide voice force 18 (manufactured by Tokai Carbon Co., Ltd. [TOKAMAX 1 (registered trademark)) and colloidal silica aqueous solution were combined with tfP and the mixture was compression molded to form the mixture shown in FIGS. 4 and 5. One curved plate-shaped fiber molded body was formed as shown in FIG. 4.The straight portion 20 of this fiber molded body 19 in FIG. The radius of curvature of the outer peripheral surface of the arc-shaped portion 21 is 39.5
nv, provided in the portion 20 and 1. : Looking at the curved part 22 in FIG. 1
It was 8 mJ l, 4.11111. Also part 2
0 was provided with two bottle insertion holes 20' with a diameter of 4 mm, and the volume fraction of silicon carbide voice force was 30%.

Next, this fiber molded body 19 was preheated to 800°C, and as shown in FIG. A molten metal 26 of aluminum alloy (JIS standard AC8B>) at 750° C. is poured into the lower mold 25, and the molten metal is solidified while being pressurized with a pressure of about 1000 kg/- in the upper mold 24. After the molten metal 26 was completely solidified, the solidified body was pushed into the lower mold 2 by a knockout pin 27.
5, and the solidified body was subjected to machining such as grinding to obtain an outer diameter of 82.4 m as shown in Figures 1 to 3.
The piston had a thickness of 74n+m.

A thermal expansion test was conducted on the piston formed as described above in the following manner. In the test, the head part 1 of the piston was heated to 320°C for 30 minutes using a burner.
In this case, the change in length in the diametrical direction between the surfaces of the skirt shoulder portion 13 was measured. For comparison, a piston with the same size and shape but not cast in a strut, and a steel (S)
A similar test was conducted on a conventional piston in which a plate-shaped strut made of PCG was cast. The results of this test are shown in Figure 7. ．． In FIG. 7, the thermal expansion ratio refers to a percentage value when the thermal expansion amount of the piston without a strut is set as 100.

From FIG. 7, it can be seen that in the piston formed as described above, the expansion and expansion of the skirt shoulder portion of the piston is effectively suppressed by the silicon carbide voice force. In addition, the piston formed as described above has a steel strut cast into it (weight approx. 342k (1) J: Rimo 21
g It was recognized that it was lightweight.

In addition, as described above (the formed piston is 6 cylinders, m exhaust m
2759cc, P, large output 170P S/56
00rDM, 1 person torque 24. ,0kgm/7140
When test operation was carried out for 200 hours under a full load at a rotational speed of 560 rpm using a 4-cycle gasoline engine, it was found that the effect of reducing diameter expansion and reduction of C noise was observed. There were no problems such as seizure, and the weight reduction resulted in improvements in revving and output.

Moreover, a piston having the same structure as the piston shown in FIGS.
It was manufactured by forming a rat and casting the slat.

First, a mixture of the same silicon carbide whiskers as the silicon carbide whiskers used in the above-mentioned examples and an aqueous colloidal silica solution was compression molded to obtain a length of 180 mm.
A cylindrical Il fiber molded body 19' having a thickness of 1.4 mm and a thickness of 1.4 mm was formed. Next, after preheating this fiber molded body to 800°C, it is placed at a predetermined position in the lower mold 29 of the high-pressure casting device 28, as shown in FIG. (JIs standard △C8, A > melting 11
30, and the molten metal is poured into the upper mold 31 to weigh approximately 1000 kg/]
The mixture was solidified while being pressurized at a pressure of . After the molten W30 has completely solidified, the solidified body is removed from the lower mold 2 by the knockout pin 32.
9, and subjected the solidified body to mechanical processing such as grinding and cutting to give it a shape as shown in FIGS. 4 and 5, which is the same as one fiber molded body in the previous example. A composite strut was formed having dimensions of . The volume fraction of carbon-41 miscellaneous in this annular body was approximately 30%.

Next, the strut thus formed is placed in a predetermined position in a mold for casting a piston, and an aluminum alloy (JIs standard AC8) is placed in the mold.
Pour the molten metal △), and after the molten metal has completely solidified, mold J,
The solidified body is taken out, and the solidified body is subjected to machining such as grinding to form a piston similar to the piston shown in FIGS. 1 to 3.

The piston thus formed was subjected to a thermal expansion test in the same manner as in the previous example.

The results of this test are shown in FIG. From FIG. 9, it can be seen that according to the piston formed as described above, the screws 1 to 1 are
- It can be seen that the expansion of the diameter of the shoulder part is effectively suppressed 3.
It has also been found that the piston formed as described above has a lighter weight of 21° compared to a conventional piston (weight 342 mm) with cast steel struts.

Furthermore, as in the previous embodiment, J=, i! When a piston formed as shown in FIG. As a result of the reduction, a reduction in noise was observed, no seizure with the cylinder bore was observed, and as a result of the weight reduction, improvements in blow-up and output were observed.

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

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a tenth embodiment of a piston according to the present invention, and FIG. 2 is a vertical sectional view taken along line IT-II in FIG. 7
1 side view, Figure 3 is a plan cross-sectional view taken along the line 6 is an illustration showing the casting process of the piston shown in FIGS. 1 to 3, FIG. 7 is a graph showing the results of a thermal expansion test, and FIG. 8 is a diagram showing the piston other than the piston according to the present invention. FIG. 9 is a diagram showing the casting process of an annular body cast during the production of one embodiment of the invention, and FIG. 9 is a graph showing the results of a thermal expansion test. 1...Head part, 2.3...Combustion chamber recess, 4...
side wall. 5.6... Compression ring iR+7... Oil ring groove, 8... Axis line, 9... Oil drain groove, 10... Piston pin hole, 11... Axis line, 12
...Skirt portion, 14...First region, 15...
Side outer peripheral surface, 16... Second region, 17... Curved portion, 18... Silicon carbide voice force, 19... Fiber molded body, 20... Straight portion, 20' ... Bottle insertion holes 9, 21 ... Arc-shaped part, 22 ... Curved part, 23 ... Casting device, 24 ... Upper mold, 25 ...
Lower mold, 26... Molten aluminum alloy, 27 Kawa no Tsukuau [-bottle, 28... Casting device, 29... Lower mold, 30... Molten aluminum alloy. 31...Upper mold, 32...Knockout pin patent
Applicant Toyota Motor Corporation Representative
Person Patent Attorney Masaki Akashi No. 1 Figure m-4 Figure 2 Figure 3 Figure 4 Figure Q Figure 6 Figure 8

Claims (1)

[Claims] An internal combustion engine biscuit made of light metal and having an oil ring groove and a piston pin hole.
When viewed in the axial direction of the piston, the portion between the oil ring groove and the skirt portion is substantially relative to the axis of the piston pin hole! I! The reinforcing fibers are substantially arcuate in two regions that extend directly in a straight line and in a region that extends substantially in an arc from both ends of the regions along the side outer circumferential surface of the piston. A biscuit for internal combustion engines that is compositely reinforced.