JPS6229627B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piston for an internal combustion engine whose head portion has an oval or oval cross-sectional shape.

Generally, in an internal combustion engine, in order to increase the displacement per cylinder, a cylinder hole with an oval or oval cross section is formed in the cylinder block, and a piston with the same cross section is slid into the cylinder hole. Compared to a normal piston with a circular cross-section, it is subjected to excessive explosion pressure due to the explosive combustion of the air-fuel mixture in the combustion chamber, which has a large volume, so in addition to its original function, it has sufficient rigidity to counter this, and is also lightweight. It is desired that

Therefore, the present invention focuses on reinforcing each joint between the piston pin, the connecting rod, and the pin boss, where a particularly large force is applied, with a closed frame-shaped reinforcing wall, thereby eliminating the need for a significant increase in weight. It is an object of the present invention to provide a piston for an internal combustion engine, which can significantly improve rigidity without any problems.

In order to achieve the above object, the present invention has both end faces made of circular arc surfaces and both side faces made of flat or curved surfaces smoothly connected to both end faces, and the cross-sectional shape is oval or elliptical. A piston for an internal combustion engine that slides into a cylinder hole having a cross-sectional shape substantially the same as the cylinder hole.
a head portion having: a head portion integrally hanging down from the head portion to support a piston pin disposed in the longitudinal direction of the cross section of the head portion, and sandwiching a small end portion of a connecting rod connected to the piston pin; a pin boss section consisting of at least a pair of opposing pin bosses, and a cross-sectional closing frame that is integrally formed with the pin boss section, surrounds the outer periphery of the small end of the connecting rod, and integrally connects the pair of pin bosses. It is characterized by having at least a reinforcing wall portion having a shape of;

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
It is composed of a head part H, a skirt part S, a pin boss part B, and a reinforcing wall part W. Their structures will be explained in detail below.

The head portion H has both end surfaces 1, 1 formed into symmetrical arcuate surfaces, and both side surfaces 2, 2 formed into flat surfaces that smoothly connect with the end surfaces 1, 1, and a cross section thereof. The shape is oval.
Further, the two side surfaces 2, 2 may be formed into curved surfaces that smoothly connect with the two end surfaces 1, 1 which are circular arc surfaces, and in this case, the cross-sectional shape of the head portion H is an ellipse. Become. A piston ring groove 3 and an oil ring groove 4 are formed on the outer circumferential surface of the head portion H, and a piston ring and an oil ring are fitted into these grooves 3 and 4, respectively, in a conventional manner.

The skirt part S connected to the head part H exists only in a part of the skirt part S, that is, it has two gate-shaped extensions extending downward from both side faces 2, 2, which are flat or curved surfaces, of the head part H. It consists of skirt pieces 5, 5, and the middle parts of both ends and both sides are missing. Therefore, when the piston P is slidably fitted into the oval or oval cylinder hole 6 of the cylinder Cy, the entire outer circumferential surface of the head portion H comes into sliding contact with the inner surface of the cylinder hole 6. However, in the skirt portion S, only the skirt pieces 5, 5 on both sides are in sliding contact with the inner surface of the cylinder hole 6.

The pin boss portion B includes two pairs of left and right pin bosses 7, 7 and 8, 8 that are symmetrically vertically disposed from the head portion H at intervals in the longitudinal direction of the cross section thereof.
These pin bosses 7, 7 and 8, 8
is located inward from a line extending downward from both end surfaces 1, 1 of the head portion H. One piston pin 9 extending along the longitudinal direction of the cross section of the head portion H is supported through the two left and right pairs of pin bosses 7, 7 and 8, 8. Small ends of connecting rods 10, 10 are connected to the piston pin 9 between them, respectively. Each pair of pin bosses 7, 7; 8, 8 are opposed to each other with the small ends of the connecting rods 10, 10 interposed therebetween.

The reinforcing wall portion W is formed integrally with each pair of pin bosses 7, 7 and 8, 8 to form a closed frame shape, and extends below each pair of pin bosses 7, 7 and 8, 8. surrounding each connecting rod 10 and each pair of pin bosses 7, 7;
8, 8 are integrally connected to each other, and both side surfaces of the reinforcing wall portion W constitute the skirt portion S. The two closed frame-shaped reinforcing wall parts W, W are integrally connected to each other by a connecting wall 11 extending from the head part H.

When the piston P configured as described above is fitted into an oval or elliptical cylinder Cy having the same cross-sectional shape as this, the entire outer circumferential surface of the head portion H is aligned with the inner surface of the cylinder hole 6 of the cylinder Cy. Sliding contact,
On the other hand, in the skirt portion S, only the skirt pieces 5, 5 making up the skirt portion S are in sliding contact with each other, and the skirt portion S slides back and forth within the cylinder Cy hole in response to the explosion pressure within the combustion chamber.

By the way, the piston P has an oval or elliptical cross-sectional shape and has a large pressure-receiving area, so it receives a large explosion pressure and this force is transmitted to the crankshaft (not shown) via the piston pin 9 and the connecting rod 10. However, in the present invention, the reinforcing wall W integrally formed with the pin boss B is formed into a closed frame shape in cross section so as to surround the connecting rod 10 connected to the piston pin 9. Therefore, in particular, each connecting portion between the piston pin 9, which is a transmitting portion of explosive force or inertial force, and the connecting rod 10 and pin bosses 7, 7; 8, 8 is provided with a closed frame-shaped and highly rigid reinforced wall portion W By intensively reinforcing the piston P, the rigidity of the piston P can be significantly increased and its deformation can be prevented without increasing the overall weight.

Further, the pin boss part B consists of two pairs of left and right pin bosses 7, 7 and 8, 8 located inward from the downward extension line of the head part H, and each pair of pin bosses 7, 7 and
By connecting the small ends of the connecting rods 10, 10 by the piston pin 9 between the connecting rods 10, 10, between the connecting rods 10, 10 of the piston pin 9, the explosive force or inertial force is The span between the points of action can be made closer to each other inward than the outer end surface of the piston P. This reduces the bending moment that acts on the piston P against the explosive force or inertial force that is applied to the piston P, and increases the rigidity of the piston. It is further enhanced.

In the embodiment described above, by forming a small gap between the connecting wall 11 and the piston pin 9,
Lubricating oil flows into the small gap and can satisfactorily lubricate the space between the pin bosses 7 and 8 and the piston pin 9.

As described above, according to the present invention, the cross-sectional shape has an oval or elliptical shape by having both end faces made of circular arc surfaces and both side faces made of flat or curved surfaces smoothly connected to both end faces. A piston for an internal combustion engine that slides into a cylinder hole 6,
A head portion H having a cross-sectional shape substantially the same as that of the cylinder hole 6; integrally vertically disposed from the head portion H to support a piston pin 9 disposed in the longitudinal direction of the cross-section of the head portion H; A pin boss part B consisting of at least a pair of pin bosses 7, 7; 8, 8 facing each other while sandwiching the small ends of connecting rods 10, 10 connected to the piston pin 9; and a pin boss part B formed integrally with this pin boss part B; It has at least a reinforcing wall portion W having a cross-sectional closed frame shape that surrounds the outer periphery of the small end of the connecting rods 10, 10 and connects the one pin boss 7, 7; 8, 8 together. , connecting rod 10,10
a pair of pin bosses 7 surrounding the small end of the
7; By means of the closed frame-shaped reinforcing wall portion W that integrally connects between 8 and 8, each connecting portion between the piston pin 9, connecting rods 10, 10, and pin bosses 7, 7; 8, 8 is emphasized. It is possible to significantly increase the rigidity of the piston without significantly increasing its weight as a whole, which is advantageous in reducing the weight of the piston. Even if a large explosive force or inertial force acts on each of the above-mentioned connecting parts due to the surface shape, the connecting parts can sufficiently withstand. In addition, since the piston pin 9 is disposed in the longitudinal direction of the cross section of the piston head H, even if the piston makes a so-called oscillation movement when the piston slides, the amount of vibration can be reduced, and the posture of the piston can be controlled. It's easy.

[Brief explanation of the drawing]

FIG. 1 is a partially longitudinal side view of the piston of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a bottom view thereof. B...Pin boss part, H...Head part, S...Skirt part, W...Reinforcement wall part, 6...Cylinder hole, 7, 8...Pin boss, 9...Piston pin, 10...Connecting rod. 〓〓〓〓〓

Claims (1)

[Scope of Claims] 1. A cylinder hole having both end faces made of circular arc surfaces and both side faces made of flat or curved surfaces smoothly connected to both end faces, and having an oval or elliptical cross-sectional shape. A piston for an internal combustion engine that is slidably engaged with a cylinder hole 6, and a head portion H having a cross-sectional shape substantially the same as that of the cylinder hole 6; A pin boss section is formed of at least a pair of pin bosses 7, 7; 8, 8, which are integrally hung down from the head section H and are opposed to each other with the small ends of the connecting rods 10, 10 connected to the piston pin 9 being sandwiched therebetween. B, and is formed integrally with this pin boss part B,
the pair of pin bosses 7, 7 surrounding the outer periphery of the small end portions of the connecting rods 10, 10;
A piston for an internal combustion engine, the piston having at least a reinforcing wall portion W having a cross-section closed frame shape integrally connecting the pistons 8 and 8. 2. In the piston for an internal combustion engine according to claim 1, the pin boss portion B is located inward from a downward extension line of both end surfaces in the longitudinal direction of the cross section of the head portion H, and is connected to two left and right connectors. It consists of two pairs of left and right pin bosses 7, 7; 8, 8 for supporting the piston pin 9 for connecting the bearing rods 10, 10, and each pair of pin bosses 7, 7; A piston for an internal combustion engine, which is integrally provided with shaped reinforcing wall parts W, W. 3. The piston for an internal combustion engine according to claim 1, wherein a part of the reinforcing wall portion W having a closed frame shape in cross section forms a skirt portion S.