JP2006214298A - Piston of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston of an internal combustion engine, achieving enough cooling for a piston head while holding down the thickness of a land part to reduce the weight. <P>SOLUTION: A through passage penetrating from one skirt side to the other skirt side is provided on the more crest surface side than a piston pin of at least one piston pin, thereby generating a swirl stream of lubricating oil from the inner peripheral side of one skirt through the through passage to the inner peripheral side of the other skirt. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piston for an internal combustion engine.

Conventionally, in a piston of an internal combustion engine, in order to cool the piston head, an annular oil passage is provided inside the land portion of the piston head to introduce oil. This annular oil passage is provided on the inner peripheral side of the piston ring, and is provided so as to supply oil from an oil jet provided on the crank chamber side (see, for example, Patent Document 1).
JP 2004-232589 A

  However, in the above prior art, since the annular oil passage is a tunnel-like oil passage provided inside the land portion of the piston head, the land portion needs to be thick enough to form the annular oil passage. . For this reason, the weight of the apparatus is increased, which hinders weight reduction.

  The present invention has been made paying attention to the above-mentioned problems. The object of the present invention is to provide a piston for an internal combustion engine that achieves sufficient cooling of the piston head while suppressing the thickness of the land portion and reducing the weight. It is to provide.

  In order to achieve the above object, in the present invention, in the piston of the internal combustion engine, a penetrating passage penetrating from one skirt side to the other skirt side is provided on the crown side of the piston pin of at least one piston pin boss, The lubricating oil generates a swirling flow that flows from the inner peripheral side of the one skirt to the inner peripheral side of the other skirt through the inside of the through passage.

  Therefore, it is possible to provide a piston for an internal combustion engine that can sufficiently cool the piston head while suppressing the thickness of the land portion.

  Hereinafter, the best mode for realizing a piston of an internal combustion engine of the present invention will be described based on an embodiment shown in the drawings.

[Configuration of piston head]
Example 1 will be described with reference to FIGS. 1 and FIG. 2 are AA and BB cross-sectional views of the piston head 1 according to the first embodiment of the present invention, FIG. 3 is a front view of the z-axis direction, and FIG. 4 is a partial cross-sectional view of I-O-II. (See FIG. 5). Note that the movement axis direction of the piston head 1 is defined as the y axis, and the crank chamber side in the engine is defined as a negative direction, and the combustion chamber side is defined as a positive direction. Furthermore, the axial direction of the piston pin 3 is defined as the z-axis, and the axis orthogonal to each of the z-axis and the y-axis is defined as the x-axis.

  The outer periphery of the piston head 1 extends in the negative y-axis direction and has a bottom by an arc-shaped skirt 12 provided on both ends of the x-axis and an apron 14 provided on both ends of the z-axis and parallel to the xy plane. Form a cup shape. The apron 14 is provided with a pin boss 13 having a z-axis direction through hole 131, and the piston pin 3 is rotatably inserted into the pin boss 13.

  An oil jet 4 is provided on the y-axis negative direction side of the piston head 1, and oil is injected / supplied to the piston head back side surface 11. The oil jetted from the oil jet 4 is provided so as to be jetted from the circumferential tangential direction of the circumferential groove 100 while being parallel to the yz plane and inclined with respect to the xz plane. By spraying from the tangential direction, the oil is easily swirled in the circumferential groove 100.

[Details of circumferential groove]
FIG. 5 is a front view of the piston head 1 in the y-axis negative direction. A circumferential groove 100 that is recessed in the positive y-axis direction is provided on the outer peripheral portion of the piston head back side surface 11 of the piston head 1, and is positioned on the outer peripheral side of the apron 14 and the inner peripheral groove portion 110 positioned on the inner peripheral side of the skirt 12. And it is formed from the penetration groove part 120 which penetrates the pin boss | hub 13 and connects with the inner peripheral side groove part 110 (refer FIG. 1, 2).

  The through groove 120 is provided between the z-axis direction through hole 131 of the pin boss 13 and the piston head back side surface 11. Further, the through-groove 120 opens at the outer periphery of the apron 14 and forms a discharge passage 123 for discharging a part of the oil introduced into the circumferential groove 100 (see FIG. 3). Grooves are formed in the inner periphery of the skirt 12 and the outer periphery of the apron 14 to reduce the volume of the piston head 1 to reduce the weight.

  In the following, the x-axis negative and positive skirts 12 are distinguished from each other and defined as an x-axis negative skirt 12a and an x-axis positive skirt 12b, respectively. Similarly, the inner circumferential groove portion 110 is also distinguished from the x-axis negative direction side inner circumferential groove portion 111 and the x-axis positive direction side inner circumferential groove portion 112. Similarly, the pin boss 13 and the through groove portion 120 are also referred to as z-axis negative and positive direction side pin bosses 13a and 13b, and z-axis negative and positive direction side through grooves 121 and 122, respectively.

  The circumferential groove 100 functions as an oil passage used for cooling the piston head 1 and lubricating each member. Further, the oil injection position of the oil jet 4 is provided so as to be the groove 111 on the inner circumferential side 111 on the x-axis negative direction side. The injection position may be the x-axis positive direction side inner circumferential groove 112 and is not particularly limited.

  Since the inner circumferential groove portion 110 and the through groove portion 120 are a part of the circumferential groove 100, the inner circumferential groove portion 110 extends in the circumferential direction via the through groove portion 120 and communicates with each other, and each of the through grooves 121 and 122. Is also arcuate. The through groove 120 may be any as long as it communicates the inner circumferential groove 110 with a continuous curved surface, and does not have to be arcuate. Further, the through groove 120 is not particularly limited as long as it is provided on either the z-axis negative or positive direction side pin boss 13a, 13b.

  In the embodiment of the present application, the inner circumferential groove portion 110, the through groove portion 120, and the discharge passage 123 of the circumferential groove 100 are all formed by molding. It may be a cutting process and is not particularly limited. When forming a tunnel-like oil passage in the land 1a of the piston head 1, it is necessary to form it by casting using a core. However, the circumferential groove 100 of this embodiment is formed on the piston head back side surface 11. Since it is a groove, it is not necessarily required by casting. Costs are reduced by avoiding the need to use a core.

[Oil flow in piston head]
6 is a cross-sectional view taken along the line AA, FIG. 7 is a cross-sectional view taken along the line BB, and FIG. 8 is a view showing the oil flow on the piston head back surface 11. The injection direction of the oil jet 4 is parallel to the yz plane and inclined with respect to the xz plane, and the oil is injected from the z-axis negative direction side to the positive direction side with respect to the xz plane. On the other hand, since the circumferential groove 100 is parallel to the xz plane, the oil is injected with an inclination with respect to the circumferential groove 100, and the normal line of the surface where the oil reaches on the piston head back surface 11, that is, the y axis is It will incline with respect to the injection direction of the oil jet 4.

  Here, the oil is injected from the tangential direction of the circumferential groove 100 to the inner circumferential groove 111 on the x-axis negative direction side of the circumferential groove 100, so that the oil reaching the circumferential groove 100 rotates clockwise along the circumference. A swirling flow that flows in the flow direction is formed and flows over the entire circumference of the circumferential groove 100 to cool the entire piston head 1.

  At this time, the inner peripheral side groove portions 110 provided on the inner peripheral portions of the x-axis positive and negative direction skirts 12a and 12b communicate with each other through the through groove portion 120, and the inner peripheral side groove portion 110 and the through groove portion 120 are continuous. Therefore, the oil flows smoothly over the entire circumference of the circumferential groove 100 to improve the cooling efficiency.

  Along with the flow, a part of the oil is discharged from the discharge passage 123 provided on the outer diameter side of the through groove portion 120 and drops in the direction of the crank chamber. Thereby, it is possible to cool and lubricate the connecting rod 2, the piston pin 3, the cylinder and the piston head 1. Oil is easily discharged along with the reciprocating motion of the piston, and cooling and lubrication can be further improved by smoothly replacing the oil.

  In the period from the bottom dead center to the top dead center, the piston head 1 moves in a direction away from the oil jet 4, so that the oil is not easily held in the circumferential groove 100. On the other hand, in the cycle from the top dead center to the bottom dead center, the oil injection direction and the piston movement direction are opposite to each other, and the oil injected from the oil jet 4 can be sufficiently held in the circumferential groove 100.

  Since the piston reciprocates at high speed, the oil is retained in the period from the top dead center to the bottom dead center, and the swirling flow is generated, so that the oil swirl flow in the period from the bottom dead center to the top dead center. Can remain. Also, since the reciprocating cycle of the piston is short, the cycle from the top dead center to the bottom dead center is started after a short time even when the oil is difficult to turn in the cycle from the bottom dead center to the top dead center. It is possible to cool by generating a swirling flow.

  Thus, the passage of oil for cooling and lubricating the piston head 1 is secured by the circumferential groove 100, and the oil is injected from the tangential direction of the circumferential groove 100 to generate a swirling flow, thereby cooling the entire piston head 1. To do. Since this circumferential groove 100 is simply a groove provided on the piston head back side surface 11, the y-axis direction thickness of the land portion 1a is reduced compared to the case where cooling is performed by providing an oil passage in the land portion 1a. The piston head 1 can be reduced in weight and shortened in the axial direction.

  In addition, when cooling is performed by supplying oil to the tunnel-shaped oil passage in the land portion 1a, the oil that has reached a high temperature by cooling the piston head 1 remains in the tunnel-shaped oil passage until it is discharged. In the embodiment, since the oil flows in the circumferential groove 100 opened in the negative y-axis direction, the oil that has reached a high temperature can be immediately discharged. Thereby, compared with the case where it cools with a tunnel-like oil path, the improvement of cooling efficiency is anticipated.

  In the present embodiment, the oil injection direction is always parallel to the yz plane and inclined with respect to the xz plane, but at least at the piston bottom dead center and parallel to the yz plane and x There is no particular limitation as long as it is inclined with respect to the −z plane. This is because if the oil jet 4 and the piston head 1 are inclined at the bottom dead center that is the closest position, the swirling flow of oil can be reliably generated.

[Contrast of the effects of the conventional example and the embodiment of the present application]
Conventionally, in a piston of an internal combustion engine, a tunnel-like annular oil passage is provided inside the land portion of the piston head, and oil supplied from an oil jet provided on the crank chamber side is introduced into the annular oil passage. Cooling is in progress. However, in the above prior art, since the tunnel-like annular oil passage is provided inside the land portion of the piston head, the land portion needs to be thick enough to form the annular passage. For this reason, the weight of the apparatus is increased, which hinders weight reduction.

  On the other hand, in the embodiment of the present application, a through groove portion 120 that penetrates at least one of the z-axis negative and positive direction side pin bosses 13a and 13b is provided, and the inner circumference of the x-axis negative and positive direction side skirts 12a and 12b. The side communicated. The through-groove 120 is provided between the z-axis direction through-hole 131 of the pin boss 13 and the piston head back side surface 11 and extends from one of the x-axis negative and positive-side skirts 12a and 12b to the other through the through-groove 120. An oil swirl was generated.

  As a result, it is possible to cool the entire piston head 1 by supplying oil to the entire piston head back side surface 11, and in comparison with a case where a tunnel-like oil passage is provided in the land portion 1 a for cooling. It is possible to reduce the thickness in the y-axis direction, and it is possible to reduce the weight of the piston head 1 and shorten the axial direction.

  The oil injection direction is parallel to the yz plane and inclined with respect to the xz plane at least at the bottom dead center of the piston. Accordingly, at least at the bottom dead center, the oil is inclined and injected into the circumferential groove 100 parallel to the xz plane, thereby forming a swirling flow of oil along the circumferential groove 100 in a counterclockwise direction. It is possible to cool the entire piston head 1 by flowing oil over the entire circumference of the circumferential groove 100, and the piston head 1 can be efficiently cooled without providing an oil passage in the land portion 1a.

  Further, on the inner peripheral side of the x-axis negative and positive skirts 12a and 12b, circumferential inner peripheral groove portions 111 and 112 extending in the circumferential direction through the through groove portion 120 are provided, and the inner peripheral groove portions 111 are provided. , 112 is supplied with oil. The volume of the piston head 1 can be reduced by the amount of the groove provided on the inner peripheral side of the skirt 12, and the weight of the piston head 1 can be further reduced.

  The second embodiment will be described with reference to FIGS. Since the basic configuration is the same as that of the first embodiment, only different points will be described. The circumferential groove 100 of the first embodiment is a mere groove portion over the entire circumference. However, in the circumferential groove 100 of the second embodiment, the protrusions 101 are provided at positions where oil is injected, and oil is provided on both sides of the protrusion 101 in the circumferential direction. This is different from the first embodiment in that a swirling flow is generated by dispersing.

[Details of Circumferential Groove in Example 2]
9 is a cross-sectional view of the piston head 1 taken along the line C-C in the second embodiment (see FIG. 10), and FIG. 10 is a front view in the y-axis negative direction. For illustration, the pin boss 13 is omitted in FIG. In the circumferential groove 100 according to the second embodiment, a mountain-shaped protrusion 101 that protrudes in the y-axis negative direction is provided in the z-axis negative direction inner peripheral groove 111, and the oil jet 4 always injects oil to the protrusion 101. It is provided as follows. Since the oil is injected to the protrusion 101, even in the second embodiment, the normal line of the surface where the oil reaches on the piston head back surface 11 is inclined with respect to the injection direction of the oil jet 4.

[Effects of Example 2]
In the second embodiment, the injected oil is divided by the protrusion 101 in both circumferential directions of the circumferential groove 100 to form a clockwise and counterclockwise swirl flow. By providing the protrusion 101, it is possible to easily generate a swirl flow in the circumferential groove 100, and to obtain the same effect as that of the first embodiment without inclining the oil jet 4 with respect to the piston head 1. Can do.

[Other embodiments]
The best mode for carrying out the present invention has been described above based on the embodiments. However, the specific configuration of the present invention is not limited to the embodiments of the present application, and the scope of the invention is not deviated. Design changes and the like are included in the present invention.

  In the first embodiment, the circumferential groove 100 is provided along the circumference of the piston head 1 and the through groove 120 is also formed in an arc shape. However, the through groove 120 only needs to communicate with the inner circumferential groove 110 by a continuous curved surface. As shown in FIG. 11, it may be linear. Even if it is linear, the inner peripheral side of each skirt 12a, 12b can be communicated, and the entire piston head 1 can be cooled.

Further, technical ideas other than the claims that can be grasped from the above embodiments will be described below together with the effects thereof.
(A) In the piston of the internal combustion engine according to any one of claims 1 to 3,
The piston of the internal combustion engine, wherein the through passage is provided on the crown surface side of the piston pins of both piston pin bosses.

  Both piston pin bosses can be made lighter on the crown side than the piston pins, and the lubricating oil swirled from one through passage flows into the other through passage, so further weight reduction and improved cooling efficiency can be expected .

(B) In the piston of the internal combustion engine according to any one of claims 1 to 3 or (a) above,
A piston of an internal combustion engine, wherein the through passage is formed in an arc shape.

  Since it becomes circular arc shape including a skirt part, it can make lubricating oil flow easily and can aim at improvement of cooling efficiency by producing a swirl flow more smoothly.

(C) In the piston of the internal combustion engine according to any one of claims 1 to 3, or (a) and (b),
The piston of the internal combustion engine, wherein the through passage is formed continuously from the back surface of the crown surface on both skirt sides.

  Since the through passage is continuous from the skirt side, it is possible to generate a swirl flow more smoothly, and it is possible to easily flow the lubricating oil and improve the cooling efficiency.

(D) In the piston of the internal combustion engine according to any one of claims 1 to 3, or (a) to (c),
A piston for an internal combustion engine, wherein the lubricating oil is injected in a tangential direction of the piston circumference.

  By jetting in the tangential direction, a swirl flow can be easily generated.

(E) In the piston of the internal combustion engine according to any one of claims 1 to 3, or (a) to (d),
The piston of an internal combustion engine, wherein the lubricating oil is injected from an oil jet and is inclined in a circumferential direction formed on the back side of the crown surface at least at the bottom dead center of the piston.

  Since the lubricating oil injected from the oil jet is inclined with respect to the back side of the crown surface, a swirl flow can be easily formed.

(F) In the piston of the internal combustion engine according to any one of claims 1 to 3, or (A) to (E),
A piston for an internal combustion engine, characterized in that a discharge passage communicating with the outer peripheral side of the piston from the through passage is provided.

  Lubricating oil is easily circulated and cooling efficiency is improved.

(G) In the piston of the internal combustion engine according to any one of claims 1 to 3, or (a) to (f),
The piston of the internal combustion engine, wherein the through passage and the discharge passage are formed by molding.

  There is no need to cast using a core, and an inexpensive piston can be obtained.

It is AA sectional drawing of the piston head in Example 1. FIG. 4 is a cross-sectional view of the piston head taken along the line BB in Example 1. FIG. FIG. 3 is a partial cross-sectional view in the z-axis direction of the piston head according to the first embodiment. FIG. 3 is a partial cross-sectional view of the piston head according to the first embodiment taken along I-O-II. FIG. 4 is a front view of the piston head in the y-axis negative direction according to the first embodiment. FIG. 3 is a diagram illustrating the flow of oil in the AA cross section of Example 1. FIG. 3 is a diagram illustrating an oil flow in a BB cross section of the first embodiment. It is a figure which shows the flow of the oil in the piston head back surface of Example 1. FIG. FIG. 6 is a diagram showing the oil flow in the BB cross section of Example 2. FIG. 6 is a diagram illustrating an oil flow in the front in the negative y-axis direction of the second embodiment. It is a figure which shows the other Example of this-application Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston head 1a Land part 2 Connecting rod 3 Piston pin 4 Oil jet 11 Piston head back side surface 12 Skirt 12a, 12b X-axis negative, positive direction skirt 13 Pin boss 13a, 13b Z-axis negative, positive direction pin boss 14 Apron 100 Circumference Groove 101 Projection 110 Inner circumferential groove 111, 112 X-axis negative, positive inner circumferential groove 120 Through-groove 121, 122 z-axis negative, positive through-groove 123 Discharge path 131 z-axis through-hole

Claims (3)

In the piston of an internal combustion engine,
Provide a penetrating path penetrating from one skirt side to the other skirt side on the crown side of the piston pin of at least one piston pin boss,
A piston for an internal combustion engine, characterized in that the lubricating oil generates a swirling flow that flows from the inner peripheral side of the one skirt to the inner peripheral side of the other skirt through the inside of the through passage. In the piston of an internal combustion engine,
Provide a penetrating path penetrating from one skirt side to the other skirt side on the crown side of the piston pin of at least one piston pin boss,
At least when the piston is located at the bottom dead center, the normal of the surface on which the extension line of the oil jet direction of the oil jet reaches the crown surface is non-perpendicular to the jet direction of the oil jet. The piston of the internal combustion engine. In the piston of an internal combustion engine,
On the back surface of the crown surface, a circumferential groove extending in the circumferential direction is provided on the crown surface side from the piston pin of at least one piston pin boss through a through passage penetrating from one skirt side to the other skirt side,
A piston for an internal combustion engine, wherein lubricating oil is supplied to the circumferential groove.

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