JPH0653743U - Internal combustion engine pistons - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the supporting force of the support arm against the side force, reduce the outer diameter of the support arm as much as possible, and reduce the weight of the piston. [Structure] A skirt portion 15 having a lower portion of the crown portion 12,
The piston pin 17 is divided in the vertical and horizontal directions centering on the axial center of the piston pin 17 to form eight upper and lower skirt portions 18, 19. Support arms 2 extending from both sides of the pin boss portions 16 and 16 to support the upper and lower skirt portions 18 and 19.
0, 21 outward from the radial centerline Y of the skirt portion 15 orthogonal to the axis X of the piston pin 17 by about 2
It was formed in an inclined shape at an angle of 0 °.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a piston of an internal combustion engine for an automobile, for example.

[0002]

[Prior art]

 As is well known, the piston of the internal combustion engine for automobiles tilts in the cylinder during one cycle because the moment around the piston pin acts due to the lateral force of the connecting rod (conrod) and the combustion pressure or inertial force. Reciprocates while receiving side pressure from the inner surface of the cylinder. For this reason, a large friction is generated between the skirt portion of the piston and the inner surface of the cylinder, which hinders smooth reciprocating movement of the skirt portion and is easily worn.

Therefore, there is also provided, for example, a technique described in Japanese Utility Model Laid-Open No. 63-67647 which divides a skirt portion to prevent a large friction from occurring.

Explaining the outline with reference to FIG. 4 and FIG. 5, the piston has a skirt portion 2 integrally formed at a lower end portion of a crown portion 1 on a thrust side on which the side force F acts and on an opposite thrust side. The upper and lower skirt portions 3 and 4 are divided in the left-right direction, and the divided upper and lower skirt portions 3 and 4 extend from both side portions of both pin boss portions 6 and 6 that hold both ends of the piston pin 5, respectively. The support arms 7 and 8 are supported by the tips thereof.

As a result, in the skirt portion 2, since the outer peripheral surfaces of the upper skirt portions 3 and 3 and the lower skirt portions 4 and 4 having small surface areas come into contact with the inner surface of the cylinder, the contact surface area becomes small. As a result, an increase in friction with the inner surface of the cylinder is suppressed, inertia force is reduced due to weight reduction, smooth reciprocating movement of the piston is obtained, and abrasion is reduced.

[0006]

[Problems to be solved by the device]

 However, in the conventional piston structure, the support arms 7 and 8 are inclined in the Y direction of the radial center line of the skirt portion 2 orthogonal to the axis X of the piston pin 5 as shown in FIG. When the large side force F as described above acts, the support arms 7 and 8 are bent in the center line Y direction via the upper and lower skirt portions 3 and 4 as shown by the arrows in the figure. It becomes easy to deform. Therefore, the inward bending load (tensile load) is concentrated on the bases 7a and 8a connected to both sides of the pin bosses 6 and 6 of the support arms 7 and 8, and the mechanical strength of the bases 7a and 8a is weakened. There is a fear of becoming. As a result, in order to increase the support rigidity of the support arms 7 and 8, the outer diameter of the support arms 7 and 8 must be set large, and it is difficult to sufficiently satisfy the request for weight reduction of the piston. become.

[0007]

[Means for Solving the Problems]

 The present invention has been devised in view of the above-mentioned conventional problems, and the cylindrical skirt portion at the lower end of the crown portion is formed vertically and horizontally, and the divided upper portion is formed. In a piston of an internal combustion engine in which a skirt portion and a lower skirt portion are supported by a plurality of support arms extending from both sides of a pair of pin boss portions that hold both ends of a piston pin, The feature is that the skirt extends orthogonally to the axial center of the pin in the direction opposite to the radial centerline of the skirt.

[0008]

[Action]

 According to the present invention configured as described above, when a side force acts on the upper and lower skirt portions on the thrust side from the direction perpendicular to the axis of the piston pin due to combustion pressure and the like, each support arm on the thrust side passes through the upper and lower skirt portions. Try to bend and deform in the direction of the center line directly intersecting with the axis of the piston pin, but since the support arms are provided in an inclined shape in the direction opposite to the center line, the side force is applied to each support arm. It will be received along the approximate axis of. Therefore, excessive flexural deformation of each support arm is suppressed, and concentrated load in the bending direction with respect to the base of the pin boss side is prevented.

[0009]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 to 3 show an embodiment of a piston of an internal combustion engine according to the present invention. The piston that reciprocates in a cylinder 11 inside a cylinder block is made of an aluminum alloy material in a substantially circular shape. A ring land portion 14 for fitting and holding piston rings 13a, 13b, 13c in an outer ring groove is provided in the lower portion of the crown portion 12 that receives combustion pressure, and a skirt portion is provided under the ring land portion 14. Have 15. Further, a pair of pin boss portions 16, 16 for holding both ends of the piston pin 17 are provided facing each other at an angular position of 180 ° on the inner surface of the skirt portion 15 via pin holes 16a, 16a. A small end portion of a connecting rod 18 is connected to the piston pin 17.

The skirt portion 15 is divided in the vertical and horizontal directions, and the upper and lower skirt portions 18 and 19 are divided and formed at symmetrical positions with respect to the axis X of the piston pin 17 as a center. The upper and lower skirt portions 18, 19 are supported by supporting arms 20, 21 projecting outward from both side portions of the pin boss portions 16, 16.

More specifically, the upper and lower skirt portions 18 and 19 are located symmetrically with respect to the axis X of the piston pin 17, that is, immediately before and after the top dead center. Are formed on the thrust side and the anti-thrust side that receive side force due to the combustion pressure and the like, and the substantially square outer surfaces 18a and 19a are formed in an arc shape along the inner surface of the cylinder 11. ing. The outer diameter of the upper skirt portion 18 is set smaller than that of the lower skirt portion 19, and the outer diameter of the skirt shoulder portion 15a immediately below the ring land portion 14 is set to the upper skirt portion 18. It is set to be smaller than the outer diameter dimension of. Therefore, the skirt portion 15 is formed so as to gradually expand from the skirt shoulder portion 15a toward the lower skirt portion 19.

As shown in FIG. 1, the support arms 20 and 21 are formed in a plate shape, and are separated from each other from a radial centerline Y of the skirt portion 15 orthogonal to the axis X of the piston pin 17 in opposite directions. It is extended in a slanted form so as to point to. That is, each of the pin boss portions 16 and 16 extends from the base portions 20a and 21a coupled to the inner end sides of both side portions of the pin boss portions 16 and 16 to the tip portions 20b and 21b coupled to the respective upper and lower skirt portions 18 and 19. The opposite inner end surfaces 16a, 16a are inclined outward at an angle of about 20 °.

Therefore, according to this embodiment, due to the combustion pressure and the like, the upper and lower thrust portions 18, 19 on the thrust side extend from the one side surface 11a of the cylinder 11 along the center line Y as shown by the arrow in FIG. When the side force F is applied by the side force F, the support arms 20 and 21 on the thrust side tend to bend and deform inward (center line Y) direction with respect to each other via the upper and lower skirt portions 18 and 19. , 21 are formed so as to be inclined outward, so that the side force F can be received along substantially the axial centers of the support arms 20, 21. Therefore, the supporting force of each support arm 20, 21 is improved, excessive inward bending deformation is suppressed, and the generation of a central load in the bending direction on the bases 20a, 21a is prevented. Therefore, cracks and breakage of the support arms 20 and 21 can be reliably prevented, and as a result, the diameters of the support arms 20 and 21 can be reduced as much as possible, and the weight of the entire piston can be reduced.

Further, since the skirt portion 15a of the skirt portion 15 is gradually expanded from the skirt shoulder portion 15a to the lower skirt portion 19, the side force F acts on the one side surface 11a of the cylinder 11 to lower the skirt portion 19. Then, the upper skirt portion 18 is sequentially pressed and deformed inward. Therefore, each outer surface 18a, 19a and the entire outer end edge of the skirt shoulder portion 15a are pressed against the one side surface 11a of the cylinder with a uniform pressure. Therefore, localized uneven wear of the skirt portion 15 is prevented.

The cross-sectional shape of the support arms 20 and 21 is not limited to the above-mentioned embodiment, but may be triangular or elliptical.

[0017]

[Effect of device]

 As is clear from the above description, according to the piston of the internal combustion engine according to the present invention, by forming the skirt portion into the upper and lower skirt portions, the weight of the piston can be reduced and large friction can be prevented. Of course, since each support arm was extended in an inclined direction opposite to the radial centerline of the skirt section orthogonal to the piston pin axis, the support force of the support arm against the side force was increased. Is improved and strength is prevented from decreasing. As a result, the outer diameter of the support arm can be made as small as possible, and the weight of the entire piston can be reduced.

[Brief description of drawings]

FIG. 1 is a bottom view of a piston according to an embodiment of the present invention.

FIG. 2 is a front view of a piston of this embodiment.

FIG. 3 is a schematic diagram showing a state in which a piston of this embodiment is arranged in a cylinder.

FIG. 4 is a front view showing a conventional piston.

FIG. 5 is a bottom view showing a conventional piston.

[Explanation of symbols]

 12 ... Crown part 15 ... Skirt part 16 ... Pin boss part 17 ... Piston pin 18 ... Upper skirt part 19 ... Lower skirt part 20 ... Upper support arm 21 ... Lower support arm X ... Piston pin axis Y ... Center line

Claims (1)

[Scope of utility model registration request] 1. A pair of pin boss portions for holding a piston pin by forming a cylindrical skirt portion at a lower end portion of a crown portion in a vertical and horizontal direction by dividing the upper and lower skirt portions. In a piston of an internal combustion engine supported by a plurality of support arms extending from both side portions of the piston, each support arm is inclined in a direction opposite to a radial centerline of a skirt portion orthogonal to the axis of the piston pin. A piston for an internal combustion engine, which is characterized in that the piston is extended like a circle.