JP7004454B2 - Internal combustion engine piston - Google Patents

Description

The present invention relates to a piston for an internal combustion engine provided with a cooling uneven portion on a surface (rear surface) opposite to the crown surface.

As a background technique in the present technical field, a piston for an internal combustion engine described in Japanese Patent Application Laid-Open No. 2009-114981 (Patent Document 1) is known. The piston for an internal combustion engine of Patent Document 1 has at least one cooling fin attached to the back surface of the piston head (see summary and FIG. 1).

Japanese Unexamined Patent Publication No. 2009-114981

In Patent Document 1, sufficient consideration is not always given to the specific shape of the cooling fins for improving the cooling performance and the suppression of the generation of the stress concentration portion in the piston head when the cooling fins are provided. rice field. In the following description, the cooling fins will be referred to as convex fin portions, and the piston head will be referred to as a piston crown portion, or simply a crown portion.

An object of the present invention is to provide a piston for an internal combustion engine capable of improving the cooling performance of the convex fin portion and suppressing the generation of the stress concentration portion in the crown portion.

According to the present invention, in one aspect thereof, the steering device has the following configuration.

The piston head portion of the piston is provided with a cooling concave-convex portion provided with a plurality of convex fin portions and a storage recess for accommodating the plurality of convex fin portions. The concave accommodating recess is provided with an arc-shaped portion having a first radius of curvature that connects the concave bottom surface and the outer peripheral edge of the accommodating recess. The convex fin portion has a convex shape protruding toward the opposite side of the crown surface, and has an arc-shaped portion having a second radius of curvature smaller than the first radius of curvature.

According to the piston for an internal combustion engine of the present invention, the cooling performance of the convex fin portion can be improved, and the generation of the stress concentration portion in the crown portion can be suppressed.

It is sectional drawing which shows one Example which applied the piston for the internal combustion engine which concerns on this invention to a spark ignition type gasoline engine. FIG. 3 is a plan view of the piston 1 of FIG. 1 as viewed from the direction of the arrow II. It is sectional drawing which shows the III-III cross section of the piston 1 shown in FIG. It is sectional drawing which shows the IV-IV cross section of the piston 1 shown in FIG. FIG. 3 is an enlarged plan view showing the uneven portion 6 of FIG. 2. FIG. 3 is an enlarged cross-sectional view showing the VI portion shown in FIG. It is sectional drawing which shows the VII part shown in FIG. 4 enlarged. FIG. 3 is an enlarged cross-sectional view showing the VI portion shown in FIG. 3, and is a diagram showing the relationship between the depth K of the accommodating recess 6A and the height J of the convex fin portion 6B1. It is a cross-sectional view which shows the VII part shown in FIG. 4 in an enlarged view, and is the figure which shows the relationship between the depth K of the accommodation recess 6A, and the height J of a convex fin part 6B2. It is a cross-sectional view which shows the VI part shown in FIG. 3 in an enlarged view, and is the figure which shows the oil jet jet part 6E2 which is formed in the accommodation recess 6A. FIG. 3 is an enlarged plan view showing the cooling uneven portion 6 in the modified example 1. It is sectional drawing which shows the XII-XII cross section of FIG. It is a figure which shows the modification example of the piston 1 of FIG. 1, and is the top view which shows the structure of the back surface side of a piston 1. It is sectional drawing which shows the XIV-XIV cross section of the piston 1 shown in FIG. It is a figure which shows the modification example of the piston 1 of FIG. 1, and is the top view which shows the structure of the back surface side of a piston 1. It is sectional drawing which shows the XVI-XVI cross section of the piston 1 shown in FIG.

Hereinafter, an embodiment of the piston for an internal combustion engine according to the present invention will be described. In the following examples, an example in which the piston for an internal combustion engine according to the present invention is applied to a spark-ignition type gasoline engine, which is a form of an internal combustion engine, will be described. Hereinafter, the piston for an internal combustion engine will be simply referred to as a piston.

In the following description, the vertical direction may be specified and described, but this vertical direction is based on the vertical direction in FIG. 1 and does not mean the vertical direction in the mounted state of the internal combustion engine or the piston.

[Example 1]
FIG. 1 is a cross-sectional view showing an embodiment in which a piston for an internal combustion engine according to the present invention is applied to a spark-ignition type gasoline engine.

The piston 1 is slidably provided in the substantially cylindrical cylinder wall surface 102 formed in the cylinder block 101 of the engine in the vertical direction (direction along the center line 102a of the cylinder). A combustion chamber 104 is formed between the cylinder wall surface 102 and the lower surface of the cylinder head 103. The piston 1 is connected to the crankshaft 107 via a connecting rod 106 connected to the piston pin 105. The cylinder head 103 is provided with an intake port 108 and an exhaust port 109, the intake port 108 is provided with an intake valve 108A, and the exhaust port 109 is provided with an exhaust valve 109A. The intake valve 108A and the exhaust valve 109A open and close the openings to the combustion chamber 104 in the intake port 108 and the exhaust port 109.

A spark plug 110 is fixed to the cylinder head 103, and the tip of the spark plug 110 is inserted into the central upper end of the combustion chamber 104. Further, the cylinder wall surface 102 or the cylinder head 103 is provided with a fuel injection valve (not shown) for injecting fuel into the combustion chamber 104.

An oil jet injection portion 111 for cooling the lower portion of the crown portion (piston head portion) 2 of the piston 1 is provided at the lower portion of the cylinder block 101 on the exhaust side of the cylinder wall surface 102. The oil jet injection portion 111 has a shape in which the nozzle 111A on the tip side is bent into a substantially L shape, and the injection port at the tip of the nozzle 111A points to the lower portion of the piston head portion 2 on the exhaust side. ..

FIG. 2 is a plan view of the piston 1 of FIG. 1 as viewed from the direction of the arrow II. FIG. 3 is a cross-sectional view showing a section III-III of the piston 1 shown in FIG. FIG. 4 is a cross-sectional view showing an IV-IV cross section of the piston 1 shown in FIG.

The piston 1 uses an AC8A Al—Si based aluminum alloy as a base material, and the piston head portion 2, the skirt portions 3A and 3B, the apron portions 4A and 4B, and the piston pin boss portions 5A and 5B are integrally cast.

Here, the first axis L1, the second axis L2, and the third axis L3 are defined.

FIG. 2 shows a plan view in which the structure of the back surface side of the piston 1 (the side opposite to the crown surface 2A) is projected onto a plane perpendicular to the moving direction AP of the piston 1. The first axis L1, the second axis L2, and the third axis L3 are orthogonal to each other at one point, and on the plan view of FIG. 2, they are orthogonal to each other at one point of the center O_2 of the piston head portion 2 (crown surface 2A). The moving direction AP of the piston 1 coincides with the direction along the center line 102a of the cylinder wall surface 102.

The first axis L1 passes through the center O_5AB1 of the inner peripheral circle of the first piston pin hole 5A1 in a cross section perpendicular to the longitudinal direction of the piston pin 105, and is an axis parallel to the longitudinal direction of the piston pin 105. The first axis L1 is an axis that passes through the center O_5AB1 of the inner circles of the two piston pin holes 5A1 and 5B1 and coincides with a straight line segment connecting the centers O_5AB1 of the two inner circles. That is, the first axis L1 is an axis along the longitudinal direction of the piston pin 105. In this case, the first axis L1 is perpendicular to the moving direction AP of the piston 1.

The center of rotation of the piston pin 105 and the center O_5AB1 of the inner peripheral circle of the first piston pin hole 5A1 and the second piston pin hole 5B1 are clearances between the two piston pin holes 5A1 and 5B1 and the piston pin 105. Does not exactly match due to the provision of. However, the deviation due to the clearance is ignored, and the rotation center of the piston pin 105 coincides with the center O_5AB1 of the inner peripheral circle of the first piston pin hole 5A1 and the second piston pin hole 5B1, and the rotation axis of the piston pin 105 ( The center line) shall pass through the center O_5AB1 of the first piston pin hole 5A1 and the second piston pin hole 5B1.

The second axis L2 is an axis perpendicular to the moving direction AP of the piston 1 and orthogonal to the first axis L1. The third axis L3 is an axis along the moving direction AP of the piston 1, and is an axis orthogonal to the first axis L1 and the second axis L2.

The piston head portion 2 is a portion defining a combustion chamber 104 (see FIG. 1) and has a crown surface 2A facing the combustion chamber 104. Skirt portions 3A and 3B and apron portions 4A and 4B are provided on the lower side of the piston head portion 2 (the side opposite to the crown surface 2A).

The two skirt portions 3A and 3B are provided so as to be separated from each other in the circumferential direction of the piston head portion 2 along the outer peripheral edge of the lower end of the piston head portion 2 (the outer peripheral edge opposite to the crown surface 2A). .. A pair of skirt portions 3A and 3B are provided separately on the thrust side and the anti-thrust side. The skirt portions 3A and 3B are formed in an arc shape along the outer peripheral edge of the lower end of the piston head portion 2 on the plan view of FIG. Therefore, in the piston 1, the piston head portion 2 and the skirt portions 3A and 3B are formed in a substantially cylindrical shape.

That is, the skirt portion of this embodiment has a first skirt portion 3A and a second skirt portion 3B. The first skirt portion 3A is provided on one side of the piston pin boss portions 5A and 5B in the direction along the second axis L2. The second skirt portion 3B is provided on the other side of the piston pin boss portions 5A and 5B in the direction along the second axis L2.
The two apron portions 4A and 4B are provided so as to be separated from each other in the circumferential direction of the piston head portion 2 so as to be connected to both side ends in the circumferential direction of the skirt portions 3A and 3B. That is, each of the pair of the first apron portion 4A and the second apron portion 4B is arranged so as to intervene between the pair of the first skirt portion 3A and the second skirt portion 3B.

The first piston pin boss portion 5A is provided in the first apron portion 4A, and the second piston pin boss portion 5B is provided in the second apron portion 4B. The first piston pin boss portion 5A and the second piston pin boss portion 5B are formed to be thicker than other portions of the apron portions 4A and 4B. The first piston pin boss portion 5A has a first piston pin hole 5A1, and the second piston pin boss portion 5B has a second piston pin hole 5B1. The piston pin boss portions 5A and 5B are configured as a part of the apron portions 4A and 4B. Both ends of the piston pin 105 (see FIG. 1) are inserted into the piston pin holes 5A1 and 5B1, and both ends of the piston pin 105 are supported by the apron portions 4A and 4B via the piston pin boss portions 5A and 5B.

That is, the piston pin boss portion has a first piston pin boss portion 5A having a first piston pin hole 5A1 into which the piston pin 105 is inserted, and a second piston pin boss portion 5B having a second piston pin hole 5B1.

The piston head portion 2 has a disc shape formed to be relatively thick, and has a crown surface 2A defining a combustion chamber 104. In this embodiment, the crown surface 2a is flat, but a valve recess is formed on the crown surface 2A to avoid interference between the intake valve 108A and the exhaust valve 109A, and the outer peripheral portion of the crown surface 2A is formed in a convex shape. You may. Further, the piston head portion 2 is formed with a ring groove 2C on the outer peripheral surface to which a piston ring (pressure ring, oil ring, etc.) (not shown) is fitted and attached.

That is, in this embodiment, the piston head portion 2 is provided on one side of the piston pin boss portions 5A and 5B and the skirt portions 3A and 3B in the direction of the third axis. The piston head portion 2 has a piston head main body portion 2B, a ring groove 2C, a crown surface 2A, and a concavo-convex portion (cooling concavo-convex portion) 6. The crown surface 2A is provided on the opposite side (the side facing the combustion chamber 104) of the piston pin boss portions 5A and 5B of the piston head main body portion 2B in the direction along the third axis L3.

The piston head portion 2 constitutes a disk-shaped portion in the piston 1, and the skirt portions 3A and 3B form a cylindrical portion in the piston 1. The piston head portion 2 constituting the disk-shaped portion and the skirt portions 3A and 3B constituting the cylindrical-shaped portion are connected at the positions indicated by reference numerals 9 in FIG. 3, and the piston 1 is integrated with the disk-shaped portion and the cylindrical-shaped portion. It is molded. A ring groove 3C is also formed on the outer peripheral surfaces of the skirt portions 3A and 3B constituting the cylindrical portion.

Hereinafter, the configuration of the uneven portion 6 will be described with reference to FIGS. 5 to 7.

FIG. 5 is an enlarged plan view showing the uneven portion 6 of FIG. 2. FIG. 6 is an enlarged cross-sectional view showing the VI portion shown in FIG. FIG. 7 is an enlarged cross-sectional view showing the VII portion shown in FIG. Note that FIG. 6 shows a cross section perpendicular to the second axis L2, and FIG. 7 shows a cross section perpendicular to the first axis L1.

The uneven portion 6 is provided on the surface (back surface) 2D of the piston head portion 2 opposite to the crown surface 2A for cooling the piston 1. Therefore, hereinafter, the uneven portion 6 will be referred to as a cooling uneven portion.

The cooling uneven portion 6 is provided on the opposite side (back surface 2D) of the crown surface 2A of the piston head main body portion 2B in the direction along the third axis L3, and is provided with the accommodating concave portion 6A and a plurality of convex fin portions. 6B and.

The accommodating recess 6A is formed in a rectangular shape having a long side along the first axis L1, and the length l1 of the long side is a connecting point between the piston head portion 2 and the skirt portions 3A and 3B as shown in FIG. It is provided so as to extend to the vicinity of 9. In this embodiment, the upper wall surfaces 7A and 7B are provided between the short side of the accommodating recess 6A and the skirt portions 3A and 3B, and the upper wall surface 7A and 7B are provided between the short side of the accommodating recess 6A and the skirt portions 3A and 3B. It is connected by 7B.

As shown in FIGS. 2 and 4, the width w1 of the short side of the accommodating recess 6A is smaller than the distance d1 between the first piston pin boss portion 5A and the first piston pin boss portion 5B.

Further, as shown in FIG. 5, the facing inner side surfaces 6E1, 6E1 on the long side and the facing inner side surfaces 6E2, 6E2 on the short side of the accommodating recess 6A are each formed in an arc shape descending from the bottom surface 6A. ..

As described above, the accommodating recess 6A of this embodiment has a concave shape toward the crown surface 2A in the direction along the third axis L3. That is, the accommodating recess 6A has a concave shape that opens toward the opposite side of the crown surface 2A in the direction along the third axis L3. That is, the accommodating recess 6A has a concave bottom surface 6A1 and an outer portion in a predetermined region inside the concave shape from the outer peripheral edge 6A2 of the concave opening in the cross section perpendicular to the first axis L1 and the cross section perpendicular to the second axis L2. It has arc-shaped portions 6E1 and 6E2 that connect to the peripheral edge 6A2. That is, the accommodating recess 6A has an arc-shaped portion 6E1 having a cross section parallel to the third axis L3 connecting the concave bottom surface 6A1 and the peripheral edge 6A2 to a predetermined region inside the concave shape from the outer peripheral edge 6A2 of the concave opening. , 6E2. The arc-shaped portions 6E1 and 6E2 are formed with a first radius of curvature R. In this embodiment, the radius of curvature of the arc-shaped portion 6E1 and the radius of curvature of the arc-shaped portion 6E2 are configured to have the same radius of curvature R, but may be different.

The accommodating recess 6A has arc-shaped portions 6E1 and 6E2 on the entire circumference of the accommodating recess 6A in a cross section perpendicular to the third axis L3. That is, the entire circumference of the accommodating recess 6A is composed of the opposing inner side surfaces 6E1 and 6E1 on the long side of the accommodating recess 6A and the opposing inner side surfaces 6E2 and 6E2 on the short side. As a result, stress concentration can be relaxed over the entire circumference of the accommodating recess 6A.

The convex fin portion 6B has a convex shape that protrudes from the bottom surface 6A1 of the accommodating recess 6A toward the side opposite to the crown surface 2A side in the direction along the third axis L3. The convex fin portion 6B has an arc shape in which the cross section parallel to the third axis L3 has a second radius of curvature r smaller than the first radius of curvature R. When the radius of curvature of the arc-shaped portion 6E1 and the radius of curvature of the arc-shaped portion 6E2 are configured to have different radii of curvature, the second radius of curvature r is larger than either the radius of curvature of the arc-shaped portion 6E1 or the radius of curvature of the arc-shaped portion 6E2. A small radius of curvature.

In this embodiment, the arc-shaped portions (R-shaped portions) 6E1 and 6E2 near the outer peripheral edge of the accommodating recess 6A have a shape using a relatively large first radius of curvature R, so that the outer peripheral edge portion of the accommodating recess 6A is formed. Stress concentration can be relaxed. Further, by setting the arc-shaped portion (rounded portion) of the convex fin portion 6B to have a relatively small second radius of curvature r, more convex fin portions 6B can be provided.

Further, it is preferable that the convex fin portion 6B has a shape that does not protrude from the opening edge 6A2 of the accommodating recess 6A toward the side opposite to the crown surface 2A side, whereby the piston 1 is formed by using a casting die. In the case of casting, the die cutting of the piston 1 becomes easy.

In this embodiment, the plurality of convex fin portions 6B are composed of a convex fin portion 6B1 along the short side of the accommodating recess 6A and a convex fin portion 6B2 along the long side of the accommodating recess 6A. By intersecting the convex fin portion 6B1 and the convex fin portion 6B2, the convex fin portion 6B has a lattice shape, and the concave portion 6C is formed in the portion surrounded by the convex fin 6B1 and the convex fin 6B2. To.

That is, the plurality of convex fin portions 6B include a first axial direction convex fin portion 6B1 and a second axial direction convex fin portion 6B2. The convex fin portion 6B1 in the first axis direction has a shape extending in parallel with the direction of the first axis L1. The convex fin portion 6B2 in the second axis direction has a shape extending in parallel with the second axis L2 direction.

Compared with the case where the convex fin portion 6B is configured in the shape of a crosspiece, the total length of each of the plurality of convex fins 6B1 and the convex fins 6B2 is made larger, and the surface area of the uneven portion 6 for cooling is increased. Can be increased. As a result, the cooling performance of the piston 1 can be improved. Further, the piston head portion 2 receives bending stress sandwiching the piston pin 105, and the convex fin portion 6B2 in the direction along the second axis L2 can exert an effect as a reinforcing rib against this bending stress. can.

In this embodiment, since the accommodating recess 6A and the convex fin portion 6B are formed on the back surface 2D side of the piston head portion 2 of the piston 1, the accommodating recess 6A and the convex fin portion 6B are not formed. The surface area of the entire back surface 2D is larger than that of the back surface 2D. Therefore, the heat dissipation effect in the accommodating recess 6A region where the convex fin portion 6B is formed becomes large, and the cooling efficiency in the vicinity of the piston head portion 2 and the piston head portion 2 can be promoted.

In particular, since the cross section of the convex fin portion 6B is formed in an arc shape, the total surface area can be increased and the heat dissipation effect can be further enhanced. Further, since the facing inner side surfaces 6E1, 6E1 on the long side and the facing inner side surfaces 6E2, 6E2 on the short side of the accommodating recess 6A are formed in an arc shape descending from the bottom surface 6A, respectively, the accommodating recess 6A has an arc shape. The surface area of the area increases. As a result, the surface area of the entire back surface 2D of the piston head portion 2 is increased, so that the heat dissipation effect is improved and the cooling efficiency is improved.

Further, in this embodiment, the cooling uneven portion 6 has a flat surface portion 6G for measuring the thickness of the piston head portion for measuring the thickness of the piston head portion 2. The piston head portion thickness measuring flat surface portion 6G is provided inside the arc-shaped portions 6E1 and 6E2 in a cross section perpendicular to the third axis L3. Further, the flat surface portion 6G for measuring the thickness of the piston head portion has a flat surface shape parallel to the cross section perpendicular to the third axis L3.

Of the piston head portion 2, the portion inside the arc-shaped portions 6E1 and 6E2 has a relatively small wall thickness, and the thickness of this portion is important for strength management of the piston 1. Therefore, by providing the flat surface portion 6G in which the convex fin portion 6B is not formed in this portion, it is possible to measure the thickness of the piston head portion 2 with high accuracy.

FIG. 8 is an enlarged cross-sectional view showing the VI portion shown in FIG. 3, and is a diagram showing the relationship between the depth K of the accommodating recess 6A and the height J of the convex fin portion 6B1. FIG. 9 is an enlarged cross-sectional view showing the VII portion shown in FIG. 4, and is a diagram showing the relationship between the depth K of the accommodating recess 6A and the height J of the convex fin portion 6B2.

The accommodation recess 6A has a bottom surface (accommodation recess flat surface portion) 6A1 parallel to a cross section perpendicular to the third axis L3, and a plurality of convex fin portions 6B1 and 6B2 are provided in the accommodation recess flat surface portion 6A1. There is. That is, as shown in FIGS. 8 and 9, the accommodating recess 6A is provided with a flat surface region P on the bottom surface 6A1, and a plurality of convex fin portions 6B1 and 6B2 are provided on the flat surface region P. Arc-shaped portions 6E1 are provided at both ends of the plane region P in the direction along the first axis L1, and arc-shaped portions 6E2 are provided at both ends of the plane region P in the direction along the second axis L2. There is.

Since the plurality of convex fin portions 6B are provided on the accommodating concave flat surface portion 6A1, the height of the convex fin portion 6B can be easily measured and controlled as compared with the case where the convex fin portions 6B are provided on the curved surface portion. , It is possible to stably supply a piston that ensures cooling performance.

As shown in FIGS. 8 and 9, the value of the height J of the convex fin portions 6B1 and 6B2 from the accommodation recess flat portion 6A1 is larger than the value of half the depth K of the accommodation recess 6A (K / 2). Small is preferable. In other words, the value of the depth K of the accommodating recess 6A is preferably larger than the value of twice the height J of the convex fin portions 6B1 and 6B2. As a result, the surface area of the arc-shaped portions (R-shaped portions) 6E1 and 6E2 on the outer peripheral edge of the accommodating recess 6A can be increased, and the cooling effect in this portion can be improved.

The piston head portion 2 and the skirt portions 3A and 3B are the piston head and the piston skirt described in FI: F02F3 / 00,301. The piston pin boss portions 5A and 5B are piston pin boss portions described in F-term: 3J044CA27. The ring groove 2C is a ring groove described in FI: F02F3 / 00 @ B. The convex fin portion 6B is a fin described in FI: B21C37 / 22.

FIG. 10 is an enlarged cross-sectional view showing the VI portion shown in FIG. 3, and is a diagram showing an oil jet injected portion 6E2 configured in the accommodating recess 6A.

In this embodiment, as shown in FIG. 1, a pair of oil jet injection portions 111 are provided. The pair of oil jet injection portions 111 are arranged so as to be separated from each other in the direction along the second axis L2. As a result, the accommodating recess 6A has a pair of oil jet jetted portions. In this embodiment, the pair of oil jet jetted portions are composed of facing inner side surfaces 6E2 and 6E2 on one side of the accommodating recess 6A. That is, each of the pair of oil jet jetted portions 6E2 and 6E2 is provided at both ends of the accommodating recess 6 in the direction along the second axis L2.

By injecting cooling oil into the arc-shaped portions 6E2 and 6E2 at both ends in the direction along the second axis L2 of the accommodating recess 6A, the injected cooling oil is the first of the accommodating recess 6A along the arc shape. It is also supplied to the central side of the piston head portion 2 from both ends in the direction along the two-axis line L2, and the cooling performance of the central portion of the piston head portion 2 can be improved.

Further, as shown in FIG. 5, the cooling uneven portion 6 has the shortest distance l3 from the end of the convex fin portion 6B in the direction along the second axis L2 to the outer peripheral edge 6A2 of the accommodating recess 6A as the first axis L1. It is configured so as to be larger than the shortest distance l2 from the end of the convex fin portion 6B to the outer peripheral edge 6A2 of the accommodating recess 6A in the direction along the above. Therefore, in the direction along the second axis L2, the accommodating concave flat surface portion 6A1 is provided between the end portion of the convex fin portion 6B and the arc-shaped portion 6E2.

As a result, at both ends in the direction along the second axis L2, the distance l3 from the end of the convex fin portion 6B to the outer peripheral edge 6A2 of the accommodating recess 6A is relatively large, so that the oil jet injected portion The range of can be sufficiently secured.

[Change example 1]
FIG. 11 is an enlarged plan view showing the cooling uneven portion 6 in the modified example 1. FIG. 12 is a cross-sectional view showing a cross section of XII-XII of FIG. Note that FIG. 12 shows a cross section perpendicular to the first axis L1.

In this modified example, the cooling uneven portion 6 has an air vent trace portion 6F. The air vent trace portion 6F pours molten metal into the casting mold, and when casting the piston pin boss portions 5A, 5B, the skirt portions 3A, 3B, and the piston head portion 2, the air existing inside the casting mold is removed from the outside of the casting mold. It has a shape corresponding to the discharge hole for discharging. In this modification, a fin portion (air vent trace portion fin portion) 6F1 is provided on the air vent trace portion 6F. The fin portion 6F1 of the air vent trace portion has a convex shape protruding toward the opposite side of the crown surface 2A in the direction along the third axis L3.

In this modified example, by providing the fin portion 6F1 also in the air vent trace portion 6F, it is possible to secure a space for providing the air vent portion and maintain the cooling performance at the same time.

[Change example 2]
FIG. 13 is a view showing a modified example of the piston 1 of FIG. 1, and is a plan view showing a structure on the back surface side of the piston 1. FIG. 14 is a cross-sectional view showing an XIV-XIV cross section of the piston 1 shown in FIG.

In this modified example, the configuration in which the length l1 of the cooling uneven portion 6 in the direction along the second axis L2 is longer than that of the first embodiment is different from the first embodiment, and the other configurations are the same as those of the first embodiment. be.

The piston 1 has a disk-shaped portion and a cylindrical-shaped portion. The disk-shaped portion is composed of a piston head portion 2, and is provided with a crown surface 2A, a cooling uneven portion 6, and a ring groove 2C. The cylindrical portion is composed of skirt portions 3A and 3B, and a ring groove 3C is provided on the outer peripheral surface. Further, the cylindrical portion is formed continuously with the disk-shaped portion 2 in the direction along the third axis L3. Both ends of the accommodating recess 6A of the cooling uneven portion 6 in the direction along the second axis L2 are adjacent to the boundary 9 between the disk-shaped portion 2 and the cylindrical portions 3A and 3B.

In this modified example, the upper wall surfaces 7A and 7B that connect the short side of the accommodating recess 6A and the skirt portions 3A and 3B, which are provided in the first embodiment, are not provided. Therefore, the short side of the accommodating recess 6A is directly connected to the cylindrical portions 3A and 3B, or is connected to the very vicinity of the cylindrical portions 3A and 3B. Therefore, the length l1 of the accommodating recess 6A in the direction along the second axis L2 can be made longer than that of the first embodiment.

Since the accommodating recess 6A is provided up to the vicinity of the end (outer circumference) of the disk-shaped portion 2 in the direction along the second axis L2, the weight of the disk-shaped portion (piston head portion) 2 can be reduced. Further, since the accommodating recess 6A is wide, the convex fin portion 6B can be formed in a wider range, and the cooling performance can be improved.

[Change example 3]
FIG. 15 is a view showing a modified example of the piston 1 of FIG. 1, and is a plan view showing a structure on the back surface side of the piston 1. FIG. 16 is a cross-sectional view showing an XVI-XVI cross section of the piston 1 shown in FIG.

In this modified example, the configuration relating to the cooling channel 2E and the cooling channel forming region 2F is different from that of the first embodiment, and the other configurations are the same as those of the first embodiment. Hereinafter, the cooling channel 2E and the cooling channel forming region 2F will be described.

The piston head portion 2 has a cooling channel 2E and a cooling channel forming region 2F. The cooling channel 2E is a passage through which a fluid for cooling the piston head portion flows, and has an arc shape extending in the circumferential direction about the third axis L3. The cooling channel forming region 2F has a convex shape protruding toward the opposite side of the crown surface 2A in the direction along the third axis L3 so as to surround the cooling channel 2E. Both ends of the accommodating recess 6A in the direction along the second axis L2 are adjacent to the cooling channel forming region 2F.

In this modified example, when the cooling channel 2E is formed, the formed region of the cooling uneven portion 6 can be made the maximum size in the direction along the second axis L2.

Although the "cooling channel" is not defined in the F-term, "cooling means by the flow of fluid along or through the piston" described in FI: F02F3 / 20, and "fluid passage for cooling and therefore" It corresponds to the "configuration of the piston itself".

The present invention is not limited to the above-described embodiment, and some configurations can be deleted or other configurations not described can be added. Further, the configurations described in the plurality of modified examples can be combined with the configuration of one or a plurality of modified examples to the extent that there is no contradiction. By combining the configurations described in each modification with the examples, the effects of the configurations are also realized in the examples.

1 ... Piston for internal combustion engine (piston), 2 ... Piston head part (disk-shaped part), 2A ... Crown surface, 2B ... Piston head body part, 2C ... Ring groove, 2E ... Cooling channel, 2F ... Cooling channel forming area, 3A ... 1st skirt part (cylindrical shape part), 3B ... 2nd skirt part (cylindrical shape part), 3C ... ring groove, 5A ... 1st piston pin boss part, 5A1 ... 1st piston pin hole, 5B ... 2nd piston Pin boss portion, 5B1 ... 2nd piston pin hole, 6 ... Cooling uneven portion, 6A ... Containment recess, 6A1 ... Containment recess flat surface (bottom surface of accommodation recess 6A), 6A2 ... Outer peripheral edge of accommodation recess 6A, 6B ... Convex Fin part, 6B1 ... 1st axis direction convex fin part, 6B2 ... 2nd axis direction convex fin part, 6E1 ... arc shape part, 6E2 ... arc shape part (pair of oil jet injected part), 6F ... air vent Trace part, 6F1 ... Air vent trace part Fin part, 6G ... Piston head part Thickness measurement flat part, 9 ... Border between disk-shaped part and cylindrical part, 105 ... Piston pin, L1 ... First axis line, L2 ... Second axis line , L3 ... 3rd axis.

Claims (12)

In the piston for internal combustion engine
It is a piston pin boss part,
A first piston pin boss portion having a first piston pin hole into which a piston pin is inserted, and a first piston pin boss portion,
A second piston pin boss portion having a second piston pin hole into which the piston pin is inserted,
With the piston pin boss portion having
The skirt part
When the axis perpendicular to the longitudinal direction of the piston pin passes through the center of the inner peripheral circle of the first piston pin hole and is parallel to the longitudinal direction of the piston pin in the cross section perpendicular to the longitudinal direction of the piston pin, the first axis is defined as the first axis. The first skirt portion provided on one side of the piston pin boss portion in the direction along the second axis perpendicular to the first axis, and
A second skirt portion provided on the other side of the piston pin boss portion in the direction of the second axis, and a second skirt portion.
With the skirt part having
It ’s the piston head.
In the direction of the third axis orthogonal to both the first axis and the second axis, the piston pin boss portion and the skirt portion are provided on one side, and the piston head main body portion, the ring groove, and the crown surface are provided. It has an uneven part for cooling,
The crown surface is provided on the opposite side of the piston pin boss portion of the piston head main body portion in the direction of the third axis.
The cooling uneven portion is provided on the opposite side of the crown surface of the piston head main body portion in the direction of the third axis, and accommodates a plurality of convex fin portions and the plurality of convex fin portions. With a recess,
The accommodating recess has a concave shape that opens toward the opposite side of the crown surface in the direction along the third axis, and a cross section parallel to the third axis is concave from the outer peripheral edge of the concave opening to the inside of the concave shape. A predetermined region has an arc-shaped portion having a first radius of curvature, which connects the concave bottom surface and the outer peripheral edge.
The convex fin portion has a convex shape protruding toward the opposite side of the crown surface in the direction along the third axis, and the cross section parallel to the third axis is smaller than the first radius of curvature. Has an arc-shaped portion with two radii of curvature,
With the piston head part
A piston for an internal combustion engine characterized by having. In the piston for an internal combustion engine according to claim 1.
The plurality of convex fin portions are pistons for an internal combustion engine, which have a lattice shape. In the piston for an internal combustion engine according to claim 2.
The plurality of convex fin portions include a first axial convex fin portion and a second axial convex fin portion.
The convex fin portion in the direction of the first axis has a shape extending in parallel with the direction of the first axis.
The piston for an internal combustion engine, characterized in that the convex fin portion in the second axis direction has a shape extending in parallel with the direction of the second axis. In the piston for an internal combustion engine according to claim 1.
The piston for an internal combustion engine, characterized in that the accommodating recess has an arc-shaped portion on the entire circumference of the accommodating recess in a cross section perpendicular to the third axis. In the piston for an internal combustion engine according to claim 1.
The accommodating recess has a flat portion of the accommodating recess parallel to a cross section perpendicular to the third axis.
A piston for an internal combustion engine, characterized in that the plurality of the convex fin portions are provided on the accommodation recessed flat surface portion. In the piston for an internal combustion engine according to claim 1.
A piston for an internal combustion engine, characterized in that the value of the depth of the accommodating recess is larger than the value of twice the height of the convex fin portion. In the piston for an internal combustion engine according to claim 1.
The accommodating recess has a pair of oil jet jetted portions.
A pair of pistons for an internal combustion engine, each of which is provided at both ends of the accommodation recess in a direction along the second axis. In the piston for an internal combustion engine according to claim 7.
In the cooling uneven portion, the shortest distance from the end of the convex fin portion in the direction along the second axis to the outer peripheral edge of the accommodating recess is the convex fin portion in the direction along the first axis. A piston for an internal combustion engine, characterized in that it is larger than the shortest distance from the end to the outer peripheral edge of the accommodating recess. In the piston for an internal combustion engine according to claim 1.
The cooling uneven portion has an air vent trace portion and has an air vent trace portion.
In the air vent trace portion, molten metal is poured into the casting mold, and when the piston pin boss portion, the skirt portion, and the piston head portion are cast, the air existing inside the casting mold is discharged to the outside of the casting mold. It has a shape corresponding to the discharge hole for the air vent, and has an air vent trace fin part.
The piston for an internal combustion engine, characterized in that the fin portion of the air vent trace portion has a convex shape protruding toward the opposite side of the crown surface in a direction along the third axis. In the piston for an internal combustion engine according to claim 1.
The cooling uneven portion has a flat surface portion for measuring the thickness of the piston head portion.
The plane portion for measuring the thickness of the piston head portion is provided inside the arc shape portion in a cross section perpendicular to the third axis, and has a plane shape parallel to the cross section perpendicular to the third axis. A piston for an internal combustion engine, characterized by having. In the piston for an internal combustion engine according to claim 1.
The piston for an internal combustion engine has a disk-shaped portion and a cylindrical-shaped portion.
The disk-shaped portion is provided with the crown surface and the cooling uneven portion.
The cylindrical portion is formed continuously with the disk-shaped portion in a direction along the third axis, and a ring groove is provided on the outer peripheral surface.
The accommodating recess is a piston for an internal combustion engine, characterized in that both ends in a direction along the second axis are adjacent to a boundary between the disk-shaped portion and the cylindrical portion. In the piston for an internal combustion engine according to claim 1.
The piston head portion has a cooling channel and a cooling channel forming region.
The cooling channel is a passage through which a fluid for cooling the piston head portion flows, and has an arc shape extending in the circumferential direction about the third axis.
The cooling channel forming region has a convex shape that projects toward the opposite side of the crown surface in a direction along the third axis so as to surround the cooling channel.
The accommodating recess is a piston for an internal combustion engine, characterized in that both ends in a direction along the second axis are adjacent to the cooling channel forming region.

Images