JP2000179398A - Piston for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston for internal combustion engine that prevents seizures as well as generation of noise during operation as much as possible. SOLUTION: This piston is provided with a top surface portion 2, a ring land portion 3 continuing to the top surface portion 2, a skirt portion 4 continuing to the ring land portion 3, a pin boss portion 8 formed under the ring land portion 3, and a piston pin hole 11 formed in the pin boss portion 8. Further, on the inner periphery side of the skirt portion 4, a projection 15 extending radially inward is formed on the both sides in the circumferential direction where it is in contact with a segment Z orthogonalized with respect to an axis Y of a piston 1 and an axis X of the piston hole 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a piston for an internal combustion engine.

[0002]

2. Description of the Related Art A piston for an internal combustion engine includes a crown, a ring land following the crown, a skirt following the ring land, and a pin boss formed below the ring land. And a piston pin hole formed in the pin boss portion.

The piston is disposed within a cylinder with a predetermined gap, and reciprocates in the cylinder. At this time, since the connecting rod supports the piston while changing from the state inclined rightward to the state inclined leftward, the piston reciprocates while being pressed against the inner surface of the cylinder by the right or left side force. Will be.

When the side force acting on the piston changes its direction, a moment is generated around the piston pin on the piston. At this time, the piston
Generally, the rigidity of the skirt near the ring land is higher than the rigidity of the skirt far from the ring land, so that the surface pressure on the inner surface of the cylinder of the skirt near the ring land increases, and the skirt increases. May occur.

Therefore, for example, Japanese Patent Laid-Open Publication No. 3-179154 proposes a piston in which the rigidity of the skirt portion is changed. In the piston described in the above publication, a thick portion is locally provided on a skirt portion, and the pin boss portion side is thin.

[0006]

However, in the conventional example, the thick portion provided on the skirt portion is local, and the skirt portion on the pin boss portion side is thin. The skirt portion is excessively deformed, a clockwise moment acts on the piston at the top dead center of the compression stroke, and the inclination of the piston increases when the lower end of the skirt portion is pressed against the inner surface of the cylinder. Then,
Immediately after the top dead center of the compression stroke, the direction of inclination of the connecting rod changes and a counterclockwise moment acts on the piston, so that the piston rotates and the thrust side of the piston (the side in contact with the cylinder in the expansion stroke) There is a possibility that the ring land portion of the above abuts against the inner surface of the cylinder to generate a tapping sound.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and provides a piston for an internal combustion engine capable of preventing seizure and generating noise during operation as much as possible. The purpose is to do.

[0008]

SUMMARY OF THE INVENTION In view of the above, the present invention is directed to a crown portion, a ring land portion following the crown portion, a skirt portion following the ring land portion, and a lower side of the ring land portion. A piston for an internal combustion engine, comprising: a pin boss formed in the boss portion; and a piston pin hole formed in the pin boss. On both sides in the circumferential direction of the position where the line segment orthogonal to the core line touches,
It is configured such that a projection extending inward in the radial direction is formed in the circumferential direction.

According to a second aspect of the present invention, in the configuration of the first aspect, the protrusion is formed such that the maximum height position is in a plane including the axis of the piston pin hole. The height is gradually changed on both axial sides of the piston.

According to such a configuration, the piston is incorporated in the cylinder of the engine with a predetermined gap, and reciprocates in the cylinder. When the piston operates, the connecting rod supports the piston while changing from a state in which the connecting rod is inclined to the right to a state in which the connecting rod is inclined to the left.Therefore, the piston is pressed against the inner surface of the cylinder by a right or left direction side force. Slides back and forth inside.

When the side force acting on the piston changes its direction, a moment is generated around the piston pin on the piston. At this time, according to the present invention, on the inner circumferential side of the skirt portion, radially on both sides in the circumferential direction at a position where a line segment orthogonal to the axis of the piston and the axis of the piston pin hole is in contact. By forming the protrusions extending inward in the circumferential direction in the circumferential direction, excessive deformation of the skirt portion is suppressed. For this reason, a clockwise moment acts on the piston at the top dead center of the compression stroke of the piston, and when the lower end of the skirt is pressed against the inner surface of the cylinder, the inclination of the piston is reduced.

Thus, when the tilting direction of the connecting rod changes immediately after the top dead center of the compression stroke, and the piston rotates by applying a counterclockwise moment to the piston, the thrust side of the piston The hitting sound generated when the ring land portion (on the side in contact with the cylinder in the expansion stroke) abuts on the inner surface of the cylinder is reduced as much as possible.

Therefore, there is provided a piston for an internal combustion engine capable of preventing seizure and preventing generation of noise during operation as much as possible.

Further, in the invention according to claim 2, the projection is formed so that its maximum height position is in a plane including the axis of the piston pin hole, and the projection is formed in the axial direction of the piston. Since the height is gradually changed on both sides, when a thrust force acts on the piston, the contact position between the piston and the cylinder moves smoothly from the lower end of the skirt to the piston pin. Thereby, the generation of the cold slap sound by the piston is advantageously suppressed.

That is, in the low-speed and low-load operation state after the start of the engine, when the piston moves to the expansion stroke immediately after the top dead center, the contact position between the piston and the cylinder becomes
Where smooth movement from the lower end side of the skirt portion to the piston pin side is effective in suppressing cold slap noise, in the present invention, the projection is such that the maximum height position is the axial center of the piston pin hole. The piston is formed so as to be in the plane including the line, and the height is gradually changed on both sides in the axial direction of the piston. The contact position between the cylinder and the cylinder moves smoothly from the lower end of the skirt portion on the thrust side of the piston to the piston pin side, whereby the generation of cold slap noise is advantageously suppressed.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of a piston for an internal combustion engine showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

The piston for an internal combustion engine indicated by reference numeral 1 in the figure is made of an aluminum alloy material.
, An uppermost crown surface portion 2, a ring land portion 3 following the crown surface portion 2, and a skirt portion 4 following the ring land portion 3.

In this embodiment, three piston ring grooves 5, 6, 7 are formed in the ring land portion 3, and among these piston ring grooves 5, 6, 7, near the crown surface 2 side. Two piston ring grooves 5, 6
Is a compression ring groove, and a piston ring groove 7 formed adjacent to the skirt portion 4 side is an oil ring groove.

Reference numeral 8 denotes a pin boss formed below the ring land 3. The pin boss 8 is formed so as to protrude from an apron 9 formed on the skirt 4 to the inner peripheral side of the skirt 4. ing. The pin boss portion 8 is connected to the skirt portion 4 via the connection beam 10, and
The upper end is connected to the ring land 3. Also,
The pin boss portion 8 and the apron portion 9 are formed to face both sides of the axis Y of the piston 1 (see FIG. 2).

The pin boss 8 has a piston pin hole 11
Are formed to penetrate. The piston pin hole 11 is formed such that its axis X is not perpendicular to the axis Y of the piston 1 but is substantially perpendicular.

A piston pin 12 is inserted into the piston pin hole 11, and a connecting rod 13 is connected to the piston pin 12.

Reference numeral 15 denotes a protrusion formed on the inner peripheral side of the skirt portion 4 and extending inward in the radial direction. The protrusion 15
Are formed on the inner circumferential side of the skirt portion 4 on both sides in the circumferential direction at positions where a line segment Z orthogonal to the axis Y of the piston 1 and the axis X of the piston pin hole 11 contact each other. It is formed.

In the embodiment shown in FIGS. 1 and 2, the projection 15 is formed in a belt shape continuously in the circumferential direction, including the position where the line segment Z contacts. In addition, the protrusion 1
The circumferential end of 5 is smoothly connected to the connecting beam 10 in this embodiment.

The projection 15 is formed so that its maximum height is located in a plane including the axis X of the piston pin hole 11, and the height of the projection 15 is gradually increased on both axial sides of the piston 1. It is formed to change. That is, in the embodiment shown in FIG. 1 and FIG.
Is formed such that the center of the upper surface of the substantially trapezoid is in a plane including the axis X of the piston pin hole 11, and the substantially trapezoidal side surface is And is smoothly connected to the inner peripheral surface of the skirt 4. The side surface of the projection 15 has a steep slope near the ring land 3 and a gentle slope near the lower end of the skirt 4.

According to such a configuration, the piston 1 is incorporated in a cylinder of an engine (not shown) with a predetermined gap, and reciprocates in the cylinder. The piston 1
Operates, the connecting rod 13 supports the piston 1 while changing from a state inclined to the right to a state inclined to the left, so that the piston 1 is pressed against the inner surface of the cylinder by the right or left side force. Reciprocatingly slides in the cylinder.

When the side force acting on the piston changes its direction, a moment occurs around the piston pin 12 in the piston. At this time, in the present invention, a circle on the inner peripheral side of the skirt portion 4 at a position where a line segment Z orthogonal to the axis Y of the piston 1 and the axis X of the piston pin hole 11 is in contact. By forming the protrusions 15 extending inward in the radial direction on both sides in the circumferential direction in the circumferential direction, excessive deformation of the skirt portion 4 is suppressed. For this reason, when a clockwise moment acts on the piston 1 at the top dead center of the compression stroke of the piston 1, the inclination of the piston 1 becomes small.

Thus, when the tilting direction of the connecting rod 13 changes immediately after the top dead center of the compression stroke and the piston 1 is rotated by a counterclockwise moment acting on the piston 1, this piston The hitting noise generated when the ring land portion 3 on the thrust side (the side in contact with the cylinder during the expansion stroke) abuts on the inner surface of the cylinder is reduced as much as possible.

Therefore, the piston 1 for the internal combustion engine which can prevent the seizure and the generation of noise during operation as much as possible can be obtained.

The protrusion 15 is formed so that its maximum height is located in a plane including the axis X of the piston pin hole 11, and the height of the protrusion 15 is gradually increased on both axial sides of the piston 1. Since it is formed so as to change, when a thrust force acts on the piston 1, the contact position between the piston 1 and the cylinder moves smoothly from the lower end side of the skirt portion 4 to the piston pin 12 side. Thereby, the generation of the cold slap sound by the piston 1 is advantageously suppressed.

That is, in the low-speed, low-load operation state after the start of the engine, when the piston 1 moves to the expansion stroke immediately after the top dead center, the contact position between the piston 1 and the cylinder is changed from the lower end of the skirt portion 4 to the piston. Although smooth movement to the pin 12 side is effective in suppressing the cold slap sound, in the present invention, the protrusion 15
However, the maximum height position is the axis X of the piston pin hole 11.
Is formed so that the height gradually changes on both axial sides of the piston 1. When the piston 1 moves to the expansion stroke immediately after the top dead center, the piston 1 When the contact position of the cylinder is shifted from the lower end of the skirt 4 on the thrust side of the piston 1 to the piston pin 12
As a result, the generation of cold slap noise is advantageously suppressed.

FIGS. 3 to 16 show another embodiment of the present invention. These embodiments are different from the above-described embodiment in that the shape of the projection 15 is variously changed. . In each of these embodiments, the projection 15 has a line segment Z perpendicular to the axis Y of the piston 1 and the axis X of the piston pin hole 11 on the inner peripheral side of the skirt 4. The point formed in the circumferential direction on both sides in the circumferential direction of the contact position is the same as in the above embodiment.

Hereinafter, these embodiments will be described. In the description, the same components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

The embodiment shown in FIGS. 3 and 4 is different from the embodiment shown in FIG. 3 in that the projections 15 are continuously formed in the circumferential direction including the position where the line segment Z contacts. Similarly, the maximum height of the projection 15 is gradually increased at the positions on both sides in the circumferential direction than the position where the line segment Z contacts.
Further, the terminal of the projection 15 in the circumferential direction is the pin boss portion 8.
Are connected smoothly.

In the embodiment shown in FIG. 5 and FIG. 6, the projection 15 has the same structure as that of FIG.
It is formed on both sides in the circumferential direction. The maximum height of the projection 15 is substantially uniform. The protrusion 15
Has one end near the position where the line segment Z is in contact with the inner surface of the skirt portion 4 in a stepped manner, and the other end smoothly connected to the connection beam 10.

In the embodiment shown in FIGS. 7 and 8, except that the projection 15 is located at and near the position where the line segment Z is in contact,
It is formed on both sides in the circumferential direction. The maximum height of the projection 15 is gradually increased at both circumferential positions on the both sides in the circumferential direction than on the side closer to the position where the line segment Z contacts. In addition, the protrusion 1
The circumferential end of 5 has one end near the position where the line segment Z is in contact with the inner surface of the skirt portion 4 in a stepped manner,
The other end is smoothly connected to the pin boss 8.

In the embodiment shown in FIGS. 9 and 10, the projections 15 are formed on both sides in the circumferential direction except for the position where the line segment Z contacts and the vicinity thereof. The protrusion 15
Has a substantially uniform height. The end of the protrusion 15 in the circumferential direction has one end on the side close to the position where the line segment Z contacts, smoothly connected to the inner surface of the skirt portion 4, and the other end smoothly connected to the connection beam 10.

In the embodiment shown in FIGS. 11 and 12, the protrusions 15 are formed on both sides in the circumferential direction except for the position where the line segment Z contacts and the vicinity thereof. The protrusion 15
Is gradually higher at both circumferential positions on the circumferential side than on the side closer to the position where the line segment Z contacts. The end of the protrusion 15 in the circumferential direction has one end on the side close to the position where the line segment Z contacts, smoothly connected to the inner surface of the skirt portion 4, and the other end smoothly connected to the pin boss portion 8.

In the embodiment shown in FIGS. 13 and 14, the protrusions 15 are formed on both sides in the circumferential direction except for the position where the line segment Z contacts. The maximum height of the projection 15 is substantially uniform. The end of the protrusion 15 in the circumferential direction has one end on the side close to the position where the line segment Z contacts, smoothly connected to the inner surface of the skirt portion 4, and the other end smoothly connected to the connection beam 10.

In the embodiment shown in FIGS. 15 and 16, the projections 15 are formed on both sides in the circumferential direction except for the position where the line segment Z contacts. The maximum height of the projection 15 is gradually increased at both circumferential positions on the both sides in the circumferential direction than on the side closer to the position where the line segment Z contacts. The end of the protrusion 15 in the circumferential direction has one end on the side close to the position where the line segment Z contacts, smoothly connected to the inner surface of the skirt portion 4, and the other end smoothly connected to the pin boss portion 8.

In each of these embodiments as well, radially inwardly extending projections 15 are formed in the circumferential direction on both sides in the circumferential direction of the position where the line segment Z contacts the inner circumferential side of the skirt portion 4. By doing so, excessive deformation of the skirt portion 4 is suppressed. Therefore, a clockwise moment acts on the piston 1 at the top dead center of the compression stroke of the piston 1, and the inclination of the piston 1 decreases when the lower end of the skirt portion 4 is pressed against the inner surface of the cylinder.

Thus, when the inclination direction of the connecting rod 13 changes immediately after the top dead center of the compression stroke, and the piston 1 is rotated by a counterclockwise moment acting on the piston 1, this piston The hitting noise generated when the ring land portion 3 on the thrust side (the side in contact with the cylinder during the expansion stroke) abuts on the inner surface of the cylinder is reduced as much as possible.

Accordingly, a piston for an internal combustion engine is obtained which can prevent seizure and minimize the generation of noise during operation.

The projection 15 is formed so that its maximum height is in a plane including the axis X of the piston pin hole 11, and the height of the piston 15 is gradually increased on both axial sides. Since it is formed so as to change, when a thrust force acts on the piston 1, the contact position between the piston 1 and the cylinder moves smoothly from the lower end side of the skirt portion 4 to the piston pin 12 side. Thereby, the generation of the cold slap sound by the piston 1 is advantageously suppressed.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment and can be changed without departing from the spirit of the invention.
For example, although the embodiment in which the cross-sectional shape of the protrusion 15 is substantially trapezoidal is described, the present invention is not limited to this, and a triangular shape,
A semi-circular shape is also possible.

[0046]

As described above in detail, according to the present invention, there is provided a piston for an internal combustion engine capable of preventing seizure and preventing generation of noise during operation as much as possible. Can be

[Brief description of the drawings]

FIG. 1 is a sectional view of a piston for an internal combustion engine showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view of a piston for an internal combustion engine showing another embodiment of the present invention.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a sectional view of a piston for an internal combustion engine showing another embodiment of the present invention.

FIG. 6 is a sectional view taken along line AA of FIG. 5;

FIG. 7 is a cross-sectional view of a piston for an internal combustion engine showing another embodiment of the present invention.

FIG. 8 is a sectional view taken along line AA of FIG. 7;

FIG. 9 is a cross-sectional view of a piston for an internal combustion engine showing another embodiment of the present invention.

FIG. 10 is a sectional view taken along line AA of FIG. 9;

FIG. 11 is a sectional view of a piston for an internal combustion engine showing another embodiment of the present invention.

FIG. 12 is a sectional view taken along line AA of FIG. 11;

FIG. 13 is a cross-sectional view of a piston for an internal combustion engine showing another embodiment of the present invention.

FIG. 14 is a sectional view taken along line AA of FIG.

FIG. 15 is a cross-sectional view of a piston for an internal combustion engine showing another embodiment of the present invention.

16 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston 2 Crown surface part 3 Ring land part 4 Skirt part 8 Pin boss part 11 Piston pin hole 15 Projection Z line segment

Claims (2)

[Claims] 1. A crown portion, a ring land portion following the crown portion, a skirt portion following the ring land portion, a pin boss formed below the ring land portion, and a pin boss formed on the pin boss portion. A piston at an inner peripheral side of the skirt portion at a position where a line perpendicular to the axis of the piston and the axis of the piston pin hole is in contact with the piston. A piston for an internal combustion engine, wherein projections extending inward in the radial direction are formed on both sides in the circumferential direction in the circumferential direction. 2. The projection is formed such that its maximum height position is in a plane including the axis of the piston pin hole, and the height is gradually changed on both axial sides of the piston. 2. The method of claim 1, wherein
A piston for an internal combustion engine according to the above.