JPH07279754A - Piston for internal combustion engine - Google Patents

Abstract

PURPOSE:To realize a piston for an internal combustion engine having cooling structure capable of cooling a piston uniformly and unifying the rigidity distribution of a skirt part. CONSTITUTION:In a piston for internal combustion engine having a hollow part which is formed in an upper part inside of a piston 10 and in which oil is supplied, a recessed part 28 provided around the opening end part on the piston outer circumferential side of a piston pin hole 20, a first passage 40 for communicating the hollow part and the recessed part 28 with each other, and a second passage 30 which is communicated from the recessed part 28 to the lower part of the piston 10, a lower wall 41 for forming the hollow part is erected from the inner surface of the skirt part 14 of the piston 10 and extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston for an internal combustion engine, and more particularly to a piston for an internal combustion engine having a cooling structure in which oil is supplied to the internal space of the piston.

[0002]

2. Description of the Related Art As a piston cooling structure in an automobile internal combustion engine, oil is blown into the top of the piston or the internal space of the piston to cool the piston from its inner surface. In such a piston cooling structure, the thickness around the pin boss is particularly large, and the heat from the combustion chamber is conducted through the top of the piston. A structure that enables efficient cooling is required, and because the oil is overheated by the piston and the heat deterioration of the oil accelerates, it is difficult to overheat the oil itself and suppress the heat deterioration. is necessary.

Therefore, on both sides of the piston pin shaft core inside the piston, there are provided hanging walls that hang from the lower surface of the piston head and shelves that are bent continuously toward the piston pin shaft center and that extend to the vicinity of the connecting rod. hand,
A hollow portion for oil storage is formed, and oil is supplied into this hollow portion to effectively cool the pin boss portion, and the hollow portion is provided with an opening recessed portion on the piston outer peripheral surface on both sides in the axial direction of the piston pin. A cooling structure has been proposed in which the oil supplied to the hollow portion of the cylinder comes into contact with the inner surface of the cylinder bore cooled by the cooling water to be cooled and then flows out to the lower side of the piston. 1
72001 gazette).

5 to 8 are respectively a front view seen from the direction of the piston pin axis for showing an example of the cooling structure of the piston according to the above proposal, a sectional view of a cross section orthogonal to the piston pin axis, and a piston pin. It is sectional drawing of the cross section parallel to an axial direction, and a bottom view of a piston. In the figure, 10 is a piston, 12 is a piston head portion, 14 and 14 are skirt portions, 16 and 16 are sidewall portions, 18 is a pin boss portion, 20 is a piston pin hole, 24 is a hollow portion, 26 is an oil supply hole, Reference numerals 28 and 28 are open recesses, 29 and 29 are recess lower walls, 30 'and 30' are passages to a lower space, 32 is a piston ring groove, 34 is an oil ring groove, and 36 is a ring land. These are the usual components in the die piston and their detailed description is omitted here.

Further, 50 to 52 are structural parts according to the above proposal, 51 and 51 are hanging walls, 52 and 52 are shelves, and each vertical wall 51 is a skirt in the thrust-anti-thrust direction portion of the piston. It is located apart from the portion 14 and the sidewall portion 16. Each of 50 and 50 is a hollow portion 2 formed by a hanging wall 51 and a shelf 52.
4 is a passage from 4 to the opening recess 28. The oil supplied from the oil supply hole 26 is temporarily stored in the hollow portion 24 and effectively cools the high temperature piston head portion 12, the side wall portions 16 and 16 and the pin boss portion 18, and then the passage 50, After passing through 50, they flow into the opening recesses 28, 28 and come into contact with the inner surface of the cylinder bore. The cylinder bore is
Although not shown, the oil that has been cooled by normal cooling water and that has flowed into the opening recesses 28, 28 is cooled by the cylinder bore of a relatively low temperature, and its overheating is suppressed.

[0006]

FIG. 9 and FIG. 10 show
FIG. 6 is a characteristic diagram showing the rigidity distribution in the left-right direction and the up-down direction of the skirt portion as viewed from the piston pin axis direction. According to the proposed cooling structure, as shown by the dotted line (conventional) in FIG. 9, the connecting portion between each vertical wall 51 and the skirt portion 14 and the sidewall portion 16, that is, the left and right sides of the skirt portion 14 are connected. The rigidity at the ends is higher than the rigidity at the center of the skirt, and since each vertical wall 51 is separated from the skirt 14 as shown by the dotted line (conventional) in FIG.
The rigidity of the skirt portion 14 extending downward from the lower part becomes lower as it goes downward. FIG. 11 is an explanatory diagram illustrating the tendency of rigidity distribution in the piston skirt portion.

In order to correct such a rigidity distribution, for example, ribs may be provided on the sidewall portion 16 between the pin boss portion 18 and the skirt portion 14 to reinforce the ribs. The problem arises that it is difficult to construct a casting mold for casting shaped pistons, and its adoption is virtually impossible. Therefore, during operation of the internal combustion engine, the skirt portion 14 of the piston 10 receives an impact between the skirt portion 14 of the piston 10 and the cylinder bore due to the crank movement, and thermally expands due to the combustion heat. However, in the cooling structure having the rigidity distribution described above. There is a problem that the piston is deformed in a complicated manner and a crack is generated in the connecting portion.

Therefore, an object of the present invention is to provide a piston for an internal combustion engine having a cooling structure which enables uniform cooling of the piston and also uniform rigidity distribution of the skirt portion. Another object of the present invention is to provide a piston for an internal combustion engine having a cooling structure which enables uniform cooling and uniform rigidity distribution and which can use a highly reliable piston casting mold.

Specifically, according to the present invention, a cooling member having high reliability in terms of cooling performance, strength, and manufacturing is obtained by raising a shelf member for forming an oil reservoir inside the piston from a skirt portion. An object of the present invention is to provide a piston for an internal combustion engine having the above.

[0010]

A piston for an internal combustion engine according to the present invention includes a hollow portion formed above the inside of the piston and supplied with oil, and around an opening end portion of a piston pin hole on the outer peripheral side of the piston. In a piston for an internal combustion engine having a recess provided, a first passage communicating the hollow with the recess, and a second passage communicating from the recess to the lower side of the piston, a lower wall forming the hollow is formed. The piston is constructed so as to stand upright and extend from the inner surface of the skirt of the piston.

[0011]

According to this structure, the oil supplied to the hollow portion cools the pin boss together with the piston head, and then reaches the opening concave portion through the first passage to exchange heat with the cylinder block having the normal cooling means. Thus, the oil can be cooled to slow the deterioration, and can be returned to the oil pan through the second passage. Further, since the lower wall forming the hollow portion is structured to extend from the piston skirt portion, the strength of the skirt portion can be improved.

[0012]

1 to 4 are, respectively, a front view of a piston for an internal combustion engine according to the present invention as viewed from the direction of the piston pin axis to show its cooling structure, and a sectional view orthogonal to the piston pin axis. FIG. 4 is a cross-sectional view of, a cross-sectional view of a cutting plane parallel to the piston pin axial direction, and a bottom view of the piston. In the figure, 10 is a piston, 12 is a piston head portion,
14, 14 are skirt portions, 16 and 16 are sidewall portions, 18 is a pin boss portion, 20 is a piston pin hole, 24 is a hollow portion, 26 is an oil supply hole, 28 and 28 are opening concave portions,
29 and 29 are lower walls of the recess, 30 and 30 are passages to the lower space, 32 is a piston ring groove, 34 is an oil ring groove,
36 is a ring land, and these are shown in FIG.
As in FIG. 8, it is a normal component in an internally cooled piston and a detailed description thereof is omitted.

According to the present invention, instead of the hanging wall 51 and the shelf 52 hanging from the head portion 12 in the above-mentioned proposal, the skirt portion 14 and the piston inner side are provided below the piston pin axis and on both sides thereof. Towards, and
Shelves 41, 41 that are bent upward and extend to the vicinity of the outer surface of the small end of a connecting rod (not shown) are provided. Thus, as in the case of the above proposal,
A hollow portion 24 for collecting oil is formed in the upper portion inside the piston 10, and an opening concave portion 2 on the outer peripheral surface of the piston 10 is formed.
Passages 40, 40 communicating with 8, 28 are formed. The passages 30, 30 to the lower space are provided on the side wall portions 16, 16 side, that is, on both sides in the axial direction of the piston pin.

According to the cooling structure in the embodiment of the piston for the internal combustion engine according to the present invention, the oil supply hole 2
The oil supplied from 6 to the hollow portion 24 may temporarily collect in the hollow portion 24 as in the conventional case (the above proposal) to cool the piston head portion 12, the pin boss portion 18 and the sidewall portions 16 and 16. In addition to this, it becomes possible to cool the skirt portions 14, 14 as well.
After that, it flows into the opening concave portions 28, 28 through the passages 40, 40, and is cooled by coming into contact with the inner surface of the cylinder bore cooled by the cooling water, and the overheating thereof is suppressed. In addition, the volume of the hollow portion 24 is increased as compared with the conventional case, and the flow of oil can be intensified when the piston 10 reciprocates in the vertical direction, and the cooling capacity can be increased.

Further, since the shelves 41, 41 rising from the skirt portions 14, 14 and connected to the side wall portions 16, 16 are provided, the skirt portions can be viewed in the left-right direction and the vertical direction as seen from the axial direction of the piston pin. As shown in FIGS. 9 and 10 described above, the directional rigidity distributions are substantially uniform. That is, FIG.
Each shelf 4 as indicated by the solid line (invention) therein
Since 1 is connected across the left and right sides of the skirt portion 14, the rigidity of the skirt portion 14 in the left-right direction is evenly distributed, and as shown by the solid line (invention) in FIG. Since 41 is connected to the lower side of the skirt portion 14, the rigidity is evenly distributed from the upper side to the lower side where the head portion 12 is connected. In addition,
Since the shelves 41, 41 are bent upward, the strength of the shelves themselves can be increased.

According to the cooling structure of this embodiment, the following secondary effects can be further obtained. That is, (1) since the insides of the skirt portions 14 and 14 can be cooled, the thermal expansion of the skirt portion is reduced, and the clearance between the skirt portion and the cylinder bore at room temperature, that is, at the time of design can be reduced. Thereby, the attitude of the piston during operation is improved and slap noise and friction are reduced. (2) Since the rigidity of the skirt portions 14 and 14 is evenly distributed and the cooling is performed uniformly, the clearance between the skirt portion 14 and the cylinder bore can be designed to be even at normal temperature, and the slap noise during operation and Friction can be reduced.

(3) By raising the shelf 41 forming the oil reservoir from below the skirt portion 14, the undulation of the casting die is reduced and the reliability of the casting die is improved as compared with the conventional case. It will be possible. The shape inside the piston has less undulations, which improves reliability in terms of strength, and especially against the explosive force during combustion and the impact on the cylinder bore, especially the lower end of the skirt portion 14, the sidewall portion 16 and the opening. Impact resistance is improved at the connection between the lower end (29) of the recess 28 and the shelf 41. There is less deformation of the lower end of the skirt 14 during an explosion and impact on the cylinder bore, reducing slap noise and friction. (4) As compared with the conventional structure, the weight of the piston 10 is reduced and the center of gravity is lowered.
Posture is improved and slap sounds and friction are reduced.

In the above-described embodiment of the piston for an internal combustion engine according to the present invention, the shelf that forms the hollow portion that serves as an oil reservoir is formed so as to rise substantially vertically from the lower portion of the skirt portion and then bent. , The shelves need to rise from the skirt and extend inward of the piston, in which case from the lower part in a suitable position to distribute the rigidity of the skirt more evenly in the vertical direction. It is desirable to make it stand up, and as a disposition form of the shelf, for example, it may stand up obliquely upward from the skirt part, and in that case, it is possible not to provide a bent part. Is.

[0019]

As described above, according to the piston for an internal combustion engine of the present invention, the cooling action of the piston head portion and the pin boss portion and the contact with the inner surface of the cylinder bore in the cooling structure provided with the hollow portion serving as an oil reservoir. It is possible to obtain a piston in which the piston skirt portion can be cooled and the strength of the piston skirt portion is improved while ensuring the effect of preventing the oil itself from overheating. As a result, since the deformation is small, the design can be facilitated, and the slap sound and friction during driving can be reduced. Moreover, since it has a simple structure, it can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a front view of a piston for an internal combustion engine according to the present invention as seen from a piston pin axial direction.

FIG. 2 is a sectional view of a cross section of the internal combustion engine piston according to the present invention, the cross section being orthogonal to the piston pin axis.

FIG. 3 is a sectional view of a cross section parallel to the piston pin axial direction of the internal combustion engine piston according to the present invention.

FIG. 4 is a bottom view of the piston of the internal combustion engine piston according to the present invention.

FIG. 5 is a front view of a conventional piston for an internal combustion engine as seen from a piston pin axial direction.

FIG. 6 is a cross-sectional view of a cut surface of a conventional piston for an internal combustion engine, which is orthogonal to a piston pin axis.

FIG. 7 is a cross-sectional view of a cutting plane parallel to a piston pin axial direction of a conventional internal combustion engine piston.

FIG. 8 is a bottom view of a piston of a conventional piston for an internal combustion engine.

FIG. 9 is a characteristic diagram showing a lateral rigidity distribution of the piston skirt portion as viewed from the direction of the piston pin axis.

FIG. 10 is a characteristic diagram showing the rigidity distribution in the vertical direction of the piston skirt portion as viewed from the direction of the piston pin axis.

FIG. 11 is an explanatory diagram illustrating the tendency of rigidity distribution in the piston skirt portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Piston 12 ... Piston head part 14 ... Skirt part 16 ... Side wall part 18 ... Pin boss part 20 ... Piston pin hole 24 ... Hollow part 26 ... Oil supply hole 28 ... Opening recessed part 29 ... Recessed lower wall 30, 30 '... Lower part Passage to space 32 ... Piston ring groove 34 ... Oil ring groove 36 ... Ring land 40, 50 ... Passage 41, 52 ... Shelf 51 ... Vertical wall

Claims (1)

[Claims] 1. A hollow portion formed above the inside of the piston and supplied with oil, a concave portion provided around an opening end portion of the piston pin hole on the outer peripheral side of the piston, the hollow portion and the concave portion. In a piston for an internal combustion engine having a first passage communicating with the piston and a second passage communicating from the recess to the lower side of the piston, the lower wall forming the hollow portion is extended from the inner surface of the skirt portion of the piston. A piston for an internal combustion engine characterized by being present.