JPS587077Y2 - engine piston - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an engine piston.

Conventionally, engine pistons have generally been provided with a skirt section in order to maintain proper reciprocating linear motion within the cylinder.Providing a skirt section maintains correct reciprocating linear motion, but at the same time increases the weight. Not only does the power loss due to inertia increase and the adaptability (acceleration) of the engine deteriorate, but also the sliding resistance against the inner surface of the cylinder increases. In order to reduce the weight by forming a slight notch C on the skirt, or to improve the sliding between the skirt and the inner surface of the cylinder (to prevent sticking), or as shown in Fig. 2, it is possible to reduce the weight of the piston. A weight e is integrally molded on one side of the top inner wall d of the piston a, and its center of gravity X-X is eccentric to the circle center Y-Y of the piston a to reduce the slap noise. This is the current situation.

However, in the conventional piston as described above,
Providing a slight notch in the skirt part does not contribute to weight reduction in any particular way, and adding weight to reduce the slap noise will increase the weight, which increases the power loss due to inertia as mentioned above. The disadvantage was that the engine had poor adaptability.

The present invention was devised in view of the above-mentioned circumstances, and provides an engine piston that can reduce weight and reduce slap noise while maintaining reciprocating linear motion within the cylinder. The purpose is to

Embodiments of the present invention will be described below with reference to FIGS. 3 to 6.

FIG. 3 schematically shows a piston according to the present invention, in which a piston 1 is slidable along a cylinder 2 and is connected to a crank 4 via a connecting rod 3. It is something.

The details of the piston 1 are as shown in FIGS. 4 to 6, and the piston 1 has a cylindrical portion (a top portion 5 having a closed end at one end (the upper portion in the illustration) and an open end at the other end). In the illustration, the cylindrical part has a bottomed cylindrical shape, and has a bottomed cylindrical shape having a bottom (lower part), from one side part 1a to the - side part 1a on the open side end surface of the cylindrical part.
The piston 1 has a shape in which a middle part of the cylindrical part in the other side part 1b that is diametrically opposed to the piston 1 is cut off along a substantially oblique cutting line 15. A long skirt portion 14 is formed, and a short skirt portion is formed on the other side portion 1b opposite to this, and the skirt portion becomes gradually shorter from the long skirt portion 14 to the short skirt portion. This causes the center of gravity position XX of the piston a to be eccentric with respect to the circular center YY of the piston a.

In addition, if necessary, ribs 1 may be added to the long skirt portion 14.
6, the center of gravity position XX can be further eccentric with respect to the circular center Y-Y of the piston a.

On the outer circumferential surface of the piston 1 on the side of the top 5, a first ring groove 6, a second ring groove 7, and a third ring groove 8 are arranged in parallel at a predetermined interval, as in the conventional case. A top ring 9 and a second ring 10 are fitted into the first ring groove 6 and the second ring groove 7, respectively, and an oil ring 11 is fitted into the third ring groove 8. Approximately at the center in the longitudinal direction of the cylindrical portion, there is a diameter that passes through the circle center Y-Y of the piston 1 and is located at an equal distance in the circumferential direction from the center of the elongated skirt portion 14 of the one side portion 1a of the piston 1. A pair of bosses 12 are formed to face each other and are bored in the same direction.

Then, insert a pin into the pair of bosses 12 and 12,
As shown in FIG. 3, it is connected to a crank 4 via a connecting rod 3.

In addition, in FIG. 4, 17 is an oil hole.

By installing the piston 1 configured as described above in the arrangement shown in FIG. 3 during the action stroke (explosion stroke), the portion of the piston 1 where the thrust force is large due to the gas pressure in the combustion chamber is The piston 1 is supported by the long skirt portion 14 of the one side portion 1a, and the portion with a small thrust force is supported by the short skirt portion of the other side portion 1b of the piston 1, so that stable linear reciprocating motion is performed. Alternatively, the long skirt portion 14 is more likely to be elastically deformed than a partial, uniform length annular shape, and therefore less likely to cause the stick phenomenon;
Further, the piston 1 has a substantially diagonal cut extending from one side portion 1a on the open side end surface of the cylindrical portion to the middle portion of the cylindrical portion on the other side portion 1b diametrically opposed to the negative side portion 1a. By cutting off along the line 15, a long skirt portion 14 is formed on the minus side portion 1a, a short skirt portion is formed on the other side portion 1b opposite thereto, and a short skirt portion 14 is formed from the long skirt portion 14. Since the skirt portion is formed so that it becomes gradually shorter toward the skirt portion of As a result, the center of gravity is eccentric, and the slap sound is reduced.

As described above, the engine piston according to the present invention has a bottomed cylindrical shape having a cylindrical portion having a top portion 5 closed at one end and an open end at the other end, and the open side of the cylindrical portion. Cut off along a substantially diagonal cutting line 15 from one side portion 1a on the end face to the middle portion of the cylindrical portion in the other side portion 1b diametrically opposed to the − side portion 1a to form the − side portion 1a. A long skirt portion 14 is formed to support a portion where the thrust force is large due to the gas pressure in the combustion chamber, and a short skirt portion that supports a portion where the thrust force is small due to the gas pressure in the combustion chamber is formed on the other side portion 1b. Since the long skirt portion 14 has a shape in which a skirt portion that becomes shorter in sequence from the long skirt portion 14 to the short skirt portion is formed, the long skirt portion 14 has the effect stroke (explosion stroke). By attaching the piston 1 to the crank 4 via the connecting rod 3 so that the piston 1 is disposed in the part where the thrust force between the cylinder and the cylinder due to the gas pressure in the combustion chamber is large, the part where the thrust force applied to the piston 1 is large is the length of the cylinder. It is supported by the long skirt portion 14, and the portion where the thrust force is small is supported by the short skirt portion,
Compared to a piston having an annular skirt portion of the same size (length), the piston 1 not only can perform linear reciprocating motion stably despite the lack of a skirt portion, but also
Since the elongated skirt portion 14 is partial, it is easily elastically deformed and the stick phenomenon is less likely to occur, and the skirt portion 14 is more flexible than an annular skirt portion having the same size (length). Since it is in a missing state, not only is the weight reduced, but the center of gravity of the piston 1 is eccentric with respect to the circular center YY, which reduces stepping noise.

[Brief explanation of the drawing]

1 and 2 are sectional views showing a conventional example, FIGS. 3 to 6 show an embodiment of the present invention, and FIG. 3 is a schematic diagram;
FIG. 4 is a cross-sectional view, and FIG. 5 is a cross-sectional view taken along the line ■-■ in FIG. 4, and a bottom view as seen from the side. 1 is a piston, 2 is a cylinder, in FIG. 6, the open end 3 is a connecting rod, 4 is a crank, 5 is a top, 14 is a long skirt, and 15 is a cutting line.

Claims (1)

[Scope of utility model registration request] It has a bottomed cylindrical shape having a cylindrical part having a closed top part 5 at one end and an open cylindrical part at the other end, and has a diameter from one side part 1a to the negative side part 1a on the open side end surface of the cylindrical part. The middle part of the cylindrical part in the other side part 1a facing the direction is cut off along a substantially oblique cutting line 15, so that the negative side part 1a supports a part where the thrust force is large due to the gas pressure of the combustion chamber. A long skirt portion 14 is formed on the other side portion 1b, and a short skirt portion is formed on the other side portion 1b to support a portion where thrust force is small due to gas pressure in the combustion chamber. 1. A piston for an engine, characterized in that the piston has a shape in which a skirt portion becomes gradually shorter toward a shorter skirt portion.