JPH0330604Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of an aluminum alloy piston used in an internal combustion engine such as a gasoline engine or a diesel engine.

[Conventional technology]

In order to improve the strength of this type of aluminum alloy piston, a strut member made of mild steel or the like is cast in the vicinity of the piston pin boss, for example.
-Disclosed in Publication No. 54248, etc.

[Problems to be solved by the invention] However, when casting a strut member into a piston in this way, the problem is how to fit the strut member into a core mold for piston casting. The question is whether to hold it. In other words, fitting and holding the strut member in a recess formed on the outer circumferential surface of the core mold prevents the molten aluminum alloy from flowing into the casting space between the core mold and the outer mold outside the core mold. Since the strut member is separated from the recess of the core mold, the strut member cannot be cast in the correct position.

The present invention solves this problem and ensures that the means for solving this problem do not adversely affect the performance of the piston.

[Means for solving problems]

Therefore, the present invention provides a piston for an internal combustion engine made of aluminum alloy in which a strut member is cast in the periphery of a piston pin boss, in which the strut member is exposed inside the piston. A pin hole into which a retaining pin protruding from the outer periphery of the casting core mold fits is bored on both left and right sides of the piston pin hole, and the piston is provided with the strut member from the inner periphery of the outer mold for casting the piston. A cast hole formed by a presser pin that protrudes to press the strut member against the core mold is provided on both left and right sides of the piston pin hole, and the pin hole in the strut member and the The cast holes in the piston are arranged to be offset from each other.

〔Example〕

The present invention will be explained below with reference to the drawings of the embodiments. In the drawings, reference numeral 1 indicates strut members 4, 4 made of a strong metal material such as mild steel or aluminum alloy, around the piston pin bosses 3, 3 for the piston pin holes 2, 2. 1 shows an aluminum alloy piston for an internal combustion engine which is made by simultaneously casting the piston 1, and 5 and 6 show a core mold and an outer mold, respectively, for casting the piston 1. Further, 12 is a core mold for the piston pin hole 2.

Pin holes 7, 7 are formed in both strut members 4 at positions exposed on the inner surface of the piston 1, and at positions on both left and right sides of the piston pin hole 2. Then, the pin holes 7, 7 are fitted and locked into a pair of left and right holding pins 8, 8 protruding from the outer peripheral surface of the casting core 5.

On the other hand, the casting outer mold 6 is provided with presser pins 9, 9 protruding toward the strut member 4 at positions on both the left and right sides of the piston pin hole 2, and these presser pins 9, 9 are used to hold the strut. Component 4 into core mold 5
to press.

As a result, the pin holes 7, 7 in both strut members 4, 4 are fitted and engaged with a pair of holding pins 8, 8 protruding from the outer periphery of the core mold 5, and the strut members 4, 4 are directed inwardly from the outer mold 6. Since it is pressed against the core mold 5 by a pair of presser pins 9, 9 that protrude from the center, it is held immovably in any of the front and rear, left and right, and up and down directions.

Therefore, even if the molten aluminum alloy is press-fitted into the casting space between the core mold 5 and the outer mold 6 outside it,
The two strut members 4, 4 are cast into a predetermined correct position without movement, and the piston 1 is formed with a cast hole 10 at each presser pin 9 in the outer mold 6.

In this case, each holding pin 8 in the core mold 5
When the presser pins 9 in the outer mold 6 are provided concentrically at the same position as shown in FIG. 8, the cast holes 10 formed by the presser pins 9 in the outer mold 6 FIG. 7 shows a piston pin recess 11 that communicates with the pin hole 7 in the strut member 4, in other words, is recessed against the piston outer circumferential surface at a portion where the piston pin hole 2 opens on the piston outer circumference. As shown, since it communicates with the inside of the piston 1 through the cast hole 10 and the pin hole 7, when lubricating oil is supplied to the piston pin by splashing it into the inside of the piston 1, A part of this lubricating oil communicates with the cast hole 10 and the pin hole 7 as described above.
Since the lubricating oil flows into the piston pin recess 11 on the outer circumferential surface of the piston through the lubricating oil and accumulates there, a large amount of oil comes up into the combustion chamber, causing a problem that the amount of lubricating oil consumed increases.

In contrast, the present invention provides a holding pin 8 into which the pin hole 7 in the strut member 4 is fitted as described above.
and the holding pin 9 on the outer mold are shifted by an appropriate dimension e in the axial direction of the piston 1. In this case, the holding pin 8 and the holding pin 9 are shifted in the circumferential direction of the piston 1, or Alternatively, the piston may be shifted in both the axial and circumferential directions.

As a result, the pin hole 7 in the strut member 4 and the cast hole 10 in the piston 1 are staggered and do not communicate with each other, so that problems caused by communication between the pin hole 7 and the cast hole 10, i.e. Therefore, it is possible to avoid an increase in the amount of lubricant consumed due to an increase in the amount of lubricant remaining in the piston pin recess 11 on the outer peripheral surface of the piston 1.

[Functions and effects of the idea]

As described above, according to the present invention, a strut member for reinforcing the piston pin boss portion of an aluminum alloy piston is provided, and a pin hole is bored in the strut member to fit into a retaining pin of a core mold for piston casting. and a presser pin protruding inward from the outer mold for piston casting, it is possible to correctly cast the piston at a predetermined position within the piston, while a pin hole that fits into the retaining pin in the core mold and a retainer pin in the outer mold Since there is no communication with the cast hole formed by the presser pin, there is an effect that there is no increase in the consumption of lubricating oil due to the communication.

[Brief explanation of the drawing]

Figures 1 to 6 show embodiments of the present invention;
The figure is a front view of the piston, and Figure 2 is the same as Figure 1.
Fig. 3 is a sectional view taken from the - side of Fig. 1, Fig. 4 is a sectional view taken from the - side of Fig. 1, and Fig. 5 is a view of the casting mold for the piston, showing the same parts as Fig. 4. 6 is a sectional view taken from the side of FIG. 5, FIG. 7 is a sectional view of the same part as FIG. 4 in a piston before the present invention, and FIG. 8 is a casting for use in the case of FIG. 7. It is a sectional view of a mold. 1... Piston, 2... Piston pin hole, 3...
...Piston pin boss, 4...Strut member,
5... Core mold for casting, 6... Outer mold for casting, 7...
...Pin hole, 8...Holding pin, 9...Press pin, 10
...Cast hole, 11...Diameter recess for piston pin.

Claims (1)

[Scope of utility model registration request] A piston for an internal combustion engine made of an aluminum alloy, in which a strut member is cast into the periphery of a piston pin boss, the strut member is exposed inside the piston, and the strut member is provided with a core mold for casting the piston. A pin hole into which a retaining pin protruding from the outer periphery of the piston is fitted is bored on both left and right sides of the piston pin hole, and the piston is provided with a pin hole extending from the inner periphery of the outer mold for casting the piston toward the strut member. A cast hole formed by a presser pin that protrudes so as to press the core against the mold,
A piston for an internal combustion engine, wherein a piston pin hole is provided on both left and right sides, and the pin hole in the strut member and the cast hole in the piston are offset from each other.