JP4306986B2 - Piston structure of internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piston structure for an internal combustion engine having an oil gallery.
[0002]
[Prior art]
An annular oil gallery is provided in the piston of the internal combustion engine near the top surface forming the bottom wall of the combustion chamber. FIG. 5 is a schematic vertical plan view of the piston 200 at the oil gallery 90 position according to the invention of Japanese Patent Application No. 2000-51143 (hereinafter referred to as the previous invention) filed by the applicant of the present application. Incidentally, in relation to the reference numerals used in the present invention, the reference numerals given to the piston 200 in FIG. 5 do not match the reference numerals used in the previous invention.
[0003]
A raised surface 91 is formed on the bottom wall 93 of the oil gallery 90. The raised surface 91 is provided with an inlet hole 92 through which lubricating oil supplied from a nozzle fixed to a cylinder block (not shown) flows. . Further, outlet holes 94 to 96 for discharging the lubricating oil in the oil gallery 90 are provided at other positions of the bottom wall 93 of the oil gallery 90. By providing the opening portion of the inlet hole 92 at a position higher than the other portions of the bottom wall 93, the lubricating oil that has entered the gallery is unlikely to flow back to the inlet hole 92.
[0004]
The inlet hole 92 penetrates to the lower side of the piston 200, and the lubricating oil is injected into the inlet hole 92 by the nozzle provided at the lower end of the inlet hole 92, so that the lubricating oil is reliably supplied into the oil gallery 90. It is like that. The outlet holes 94 to 96 are through holes penetrating the bottom wall 93, and the lubricating oil in the oil gallery 90 flows out from any of the outlet holes 94 to 96.
[0005]
In addition, the arrangement angles θ _{1 to} θ ₃ of the outlet holes 94 to 96 and the arrangement angle θ ₄ of the inlet hole 92 with respect to the orthogonal line 98 orthogonal to the piston pin center line 97 and the arrangement angle θ ₄ of the inlet hole 92 are determined by the position of the boss part that supports the piston pin. The above-mentioned problems are different due to the problem of forming the lubricating oil passage.
[0006]
By the way, even if the oil gallery 90 is configured as described above, there is still a problem that affects the cooling performance of the piston 200. The lubricating oil that has flowed into the oil gallery 90 from the inlet hole 92 is prevented from flowing back from the inlet hole 92 and flowing out of the oil gallery 90 by the raised surface 91, but the lubricating oil is high in the current internal combustion engine. It has been clarified that the gas flows out from the outlet holes 94 to 96 (especially 94 and 96) before the cooling effect to suppress the high temperature of the piston due to the output.
[0007]
Further, it is preferable to use the piston 200 as a common specification product corresponding to mass production because it leads to cost reduction. However, in the piston 200 shown in FIG. It is conceivable that the flow environment of the lubricating oil in the oil gallery 90 greatly depends on whether the inlet hole 92 comes downward or upward, and has a great influence on the cooling effect of the piston 200.
[0008]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide a piston structure including an oil gallery for an internal combustion engine that can exhibit a cooling effect corresponding to high output.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, in the piston structure of an internal combustion engine, an annular oil gallery is provided on the back surface side of the piston top wall, and three oil discharge holes provided by a core support are provided on the bottom wall of the oil gallery. and one oil inlet dedicated hole extending to the lower end, which is molded by casting punching or machining, the piston pin center line, whereas the side, the two oil discharge holes at intervals in the circumferential direction 1 oil discharge hole and oil inlet dedicated hole are arranged on the other side at intervals in the circumferential direction, and the first raised surface is formed at the position where the oil inlet dedicated hole is provided in the bottom wall. and, among the three oil discharge hole, the oil inlet dedicated hole and adjacent two oil discharge hole in the bottom wall of the positions provided, provided lower than the first raised surface second raised surface, the oil Dedicated inlet hole and oil inlet One of the two oil discharge holes adjacent to the hole is arranged so as to be axisymmetric with respect to the piston pin center line, and the two of the oil discharge holes adjacent to the oil inlet dedicated hole are arranged. The other and the oil discharge hole which is not adjacent to the oil inlet dedicated hole are arranged so as to be symmetrical with respect to the piston pin center line .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
( First embodiment )
FIG. 2 is a longitudinal front view of the piston 100 of the internal combustion engine embodying the present invention. 1 is a cross-sectional view taken along the line II of FIG. As shown in FIG. 2, the piston 100 is provided with an annular oil gallery 1. The oil gallery 1 is partitioned by a top wall 3, a bottom wall 4, an inner wall 17 and an outer wall 18.
[0011]
The top wall 3 and the inner wall 17 of the oil gallery 1 partition the combustion chamber 2 and the oil gallery 1. Therefore, the heat generated by the combustion performed in the combustion chamber 2 is directly transmitted to the top wall 3 and the inner wall 17.
[0012]
As shown in FIG. 1, a raised portion 14 is provided on the bottom wall 4 of the oil gallery 1. The raised portion 14 is provided with a lubricating oil supply hole 5. Further, the bottom wall 4 is provided with raised portions 15 and 16 lower than the raised portion 14. The raised portion 15 is provided with a discharge hole 6 for discharging high-temperature lubricating oil in the oil gallery 1, and the raised portion 16 is similarly provided with a discharge hole 8. The height of the raised portions 15 and 16 is set to, for example, 1/3 to 1/3 of the height of the raised portion 14. Further, the bottom wall 4 is provided with a discharge hole 7.
[0013]
As shown in FIG. 1, the lubricating oil supply hole 5 and the discharge holes 6 to 8 are arranged at an arrangement angle θ with respect to an orthogonal line 13 orthogonal to the piston pin center line 12. The arrangement angle θ can be set to an angle between 30 degrees and 60 degrees, for example. In the conventional piston 200 (FIG. 5), only the arrangement angle of the inlet hole 92 is different from the arrangement angles of the outlet holes 94 to 96, but here, all the arrangement angles shown in FIG. 1 can be set to θ. Are provided with a boss portion for supporting the piston pin and a lubricating oil passage 9.
[0014]
As shown in FIG. 2, when the piston 100 reaches bottom dead center, the tip (upper end) of the lubricating oil injection nozzle 11 (FIG. 2) fixed to a cylinder block (not shown) moves from the lower end of the piston 100 to the combustion chamber 2. Is accommodated at the lower end of the lubricating oil passage 9 (FIG. 2) extending in the direction of.
[0015]
Lubricating oil injected from the lubricating oil injection nozzle 11 passes through the lubricating oil passage 9 and enters the oil gallery 1 from the lubricating oil supply hole 5. The lubricating oil in the oil gallery 1 is shuffled when the piston 100 reciprocates between the top dead center and the bottom dead center, and adheres to the top wall 3 and the inner wall 17 of the oil gallery 1 that also serves as the wall surface of the combustion chamber 2. To cool hot walls.
[0016]
The lubricating oil heated by cooling the wall surface of the combustion chamber 2 falls from the discharge holes 6 to 8 into the crank chamber 10 (FIG. 2) spreading below the piston 100 and is stored in an oil pan (not shown).
[0017]
Although FIG. 1 shows an example in which the raised portions 15 and 16 are formed on the bottom wall 4 provided with the two discharge holes 6 and 8, the raised portions 15 and 16 are also formed at the position of the discharge hole 7 on the bottom wall 4. A similar raised portion (preferably a raised portion lower than the discharge holes 6 and 8) may be formed. Further, the raised portions (15, 16) may be formed in only one of the discharge holes 6 or 8.
[0018]
FIG. 3 is a partially enlarged view of the vicinity of the discharge hole 6 provided with a raised portion 15a instead of the raised portion 15 at the bottom 4 in FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. In FIG. 3, the raised part 15a is formed in the bottom wall 4, and the discharge hole 6 is provided so that this raised part 15a may be penetrated. As shown in FIG. 4, the raised portion 15a does not connect the inner wall 17 and the outer wall 18, and lubricating oil can be interposed between the inner wall 17 and the outer wall 18 and the raised portion 15a.
[0019]
The discharge holes 6 to 8 can be formed by using a core when the piston 100 is formed. The lubricating oil supply hole 5 and the lubricating oil passage 9 can be formed by casting. The lubricating oil passage 9 can be cast and formed in the skirt portion 19, but may be formed by machining using a cylindrical member.
[0020]
( Second Embodiment )
A piston 100 having the structure shown in FIGS. 1 and 2 (the configuration shown in FIGS. 3 and 4 is acceptable) is used for a V-shaped internal combustion engine. In a V-shaped internal combustion engine, the piston 100 is provided with an inclination and reciprocates in an oblique direction.
[0021]
The four lubricating oil supply holes 5 and the discharge holes 6 to 8 are all set at an angle θ with respect to the orthogonal line 13 as described above, and are in a symmetrical relationship with the piston pin center line 12. .
[0022]
Further, although the position of the lubricating oil injection nozzle 11 fixed to the cylinder block is determined, the lubricating oil supply hole 5 and the discharge holes 6 to 8 are positioned symmetrically with respect to the piston pin center line 12. The tip of the lubricant injection nozzle 11 can be accommodated at the lower end of the lubricant passage 9 by using the piston 100 having the same shape. The present embodiment is mainly applied to a V-type internal combustion engine, but can also be applied to a W-type internal combustion engine.
[0023]
【The invention's effect】
According to the present invention, a raised portion 14 (first raised surface) having a lubricating oil supply hole 5 (oil inlet dedicated hole) on the bottom wall 4 and raised portions 15 and 16 (second raised portions) having discharge holes 6 and 8 are provided. Surface) and the raised portions 15 and 16 are formed lower than the raised portion 14, so that the lubricating oil flowing into the oil gallery 1 from the lubricating oil supply hole 5 exhibits a sufficient cooling effect, and then the discharge holes 6 to 6. 8 can be discharged.
[0024]
That is, the lubricating oil in the oil gallery 1 can be replaced while exhibiting a good cooling effect. Therefore, the temperature distribution of the piston 100 is less likely to be biased, and the internal combustion engine can perform a stable operation.
[0025]
In addition, by implementing the present invention, a good cooling effect can be exerted on the piston 100 (including the combustion chamber 2), so that the operation of the internal combustion engine with high output can be stably performed.
[0026]
Further, according to the present invention, the lubricating oil supply hole 5 (oil inlet dedicated hole) and the three discharge holes 6 to 8 (oil discharge holes) are formed on the bottom wall 4 of the oil gallery 1 with respect to the piston pin center line 12. Since the pistons 100 are inclined and installed in a V-type internal combustion engine, the lubricating oil supply holes 5 of all the cylinders are used even when the same pistons 100 are used for all the cylinders. The height can be made constant, and it is possible to prevent a difference in cooling effect between the cylinders. That is, the same cooling effect can be achieved in all cylinders, and a stable operating environment of the V-shaped internal combustion engine can be provided.
[0027]
Further, by implementing the present invention, there is no restriction on the arrangement of the cylinder head and the lubricating oil pipe in the V-shaped internal combustion engine, the degree of freedom in designing the internal combustion engine is increased, the layout can be easily changed, and the space is saved. Can be achieved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view taken along the line II of FIG.
FIG. 2 is a longitudinal front view of a piston of an internal combustion engine embodying the present invention.
FIG. 3 is a partially enlarged view of the vicinity of the discharge hole provided with a raised portion having a shape different from that in FIG. 1 in the discharge hole.
4 is a cross-sectional view taken along the line IV-IV in FIG. 3;
FIG. 5 is a schematic vertical plan view of an oil gallery position of a conventional piston.
[Explanation of symbols]
1 oil galleries 2 combustion chamber 3 top wall 4 bottom 5 lubricating oil supply hole (oil inlet only hole)
6 to 8 discharge holes (oil discharge holes)
9 Lubricating oil passage 10 Crank chamber 11 Lubricating oil injection nozzle 12 Piston pin center line 13 Orthogonal lines 14-16, 15a Raised part 17 Inner wall 18 Outer wall 19 Skirt part 100 Piston θ Arrangement angle

Claims (1)

In the piston structure of an internal combustion engine,
An annular oil gallery is provided on the back side of the piston top wall,
Wherein the bottom wall of the oil gallery, and molded and three oil discharge hole by a core support, one and the oil inlet only hole extending to the piston lower part, the cast punching or machining,
Two oil discharge holes are arranged on the one side of the piston pin center line with a gap in the circumferential direction, and one oil discharge hole and an oil inlet are arranged on the other side with a gap in the circumferential direction. Holes are placed,
Forming a first raised surface at a position where the oil inlet dedicated hole is provided in the bottom wall;
Among the three oil discharge holes, a second raised surface lower than the first raised surface is provided on the bottom wall at a position where two oil discharge holes adjacent to the oil inlet dedicated hole are provided,
The oil inlet dedicated hole and one of the two oil discharge holes adjacent to the oil inlet dedicated hole are arranged so as to be symmetrical with respect to the piston pin center line,
The other of the two oil discharge holes adjacent to the oil inlet dedicated hole and the oil discharge hole not adjacent to the oil inlet dedicated hole are arranged so as to be symmetrical with respect to the piston pin center line. A piston structure for an internal combustion engine.

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