JP2007263058A - Piston for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston for an internal combustion engine capable of forming an oil reservoir space positioned in an end part of a pin boss and efficiently supplying oil to a piston pin. <P>SOLUTION: A whole circumference of an opening end 11a of the pin boss 11 is formed under condition where the same is positioned near the outermost diameter of the piston. The oil reservoir space 14 facing the pin boss 12 is formed in the end part of the pin boss 11. A communication path 16 establishing communication between a ring groove 7 positioned at a piston upper side of the pin boss 11 and the oil reservoir space 14 is provided. The communication path 16 makes oil flow from the ring groove 7 into the oil reservoir space 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

Conventionally, for example, Patent Document 1 discloses an internal combustion engine piston in which an oil sump space is provided in an end portion of a pin boss.
In Patent Document 1, the open end side of the pin boss extends to the vicinity of the outermost diameter of the piston, and the length of the pin boss in the piston radial direction is set longer than that of the piston pin. An upward recess is formed by the inner peripheral edge of the opening end below the center of the pin boss, and the recess serves as an oil reservoir (corresponding to an oil reservoir space). When the piston moves down, the lubricating oil adhering to the cylinder bore is scraped off by the oil ring. The lubricating oil scraped off is retained in the oil reservoir of the pin boss. When the piston moves up, the oil in the oil sump is splashed and supplied to the piston pin.

JP-A-6-93928

  When the above-described conventional technical matters are adopted, an opening is formed above the oil sump space by removing the upper portion of the pin boss end. For this reason, when the piston moves up and the oil in the oil sump space rises and flows, a part of the oil that bounces off the upper wall above the oil sump space flows out of the pin boss from the opening. May flow out of opening. As a result, the amount of oil supplied from the oil sump space to the piston pin is smaller than the amount of oil entering the sump space, and the amount of oil staying in the sump space is larger than the volume of the oil sump space. The oil supply efficiency to the piston pin tended to deteriorate.

  An object of the present invention is to provide a piston for an internal combustion engine in which an oil sump space is formed in an end portion of a pin boss and oil can be efficiently supplied to a piston pin.

  In the internal combustion engine piston according to the first aspect of the present invention, the entire circumference of the open end of the pin boss is formed near the outermost diameter of the piston, and the piston boss is formed in the end of the pin boss. An oil sump space, and a communication channel for communicating a ring groove located above the piston with respect to the pin boss to the oil sump space and allowing oil to flow into the oil sump space from the ring groove are provided.

  According to the configuration of the first aspect of the present invention, since the entire circumference of the open end of the pin boss is formed near the outermost diameter of the piston, the open end of the pin boss is close to the inner surface of the cylinder, and the oil sump space is the open end of the pin boss It becomes difficult to open to the outside of the pin boss through. As a result, even if the piston moves up and the oil in the oil reservoir space rises and flows, the oil is less likely to flow out of the oil reservoir space. This makes it difficult for oil to enter the oil sump space from the open end of the pin boss. However, when the piston moves down, the ring in the ring groove scrapes the lubricating oil from the inner surface of the cylinder. The scraped oil enters the ring groove and flows into the communication path, and enters the oil pool space from the communication path. In this way, it is possible to obtain a high-quality piston for an internal combustion engine that can enhance the oil holding effect of the oil reservoir space and efficiently supply the oil to the piston pin to effectively lubricate and cool the piston pin.

  In the second aspect of the invention, the communication passage communicates the ring groove closest to the pin boss with the oil sump space among the plurality of ring grooves arranged in the piston vertical direction above the pin boss on the piston upper side. I am letting.

  According to the configuration of the second aspect of the invention, when the piston moves down, the ring located in the lowest ring groove of the plurality of ring grooves is preceded by the ring located in the upper ring groove, and the cylinder inner surface The oil can be scraped off. In other words, oil enters the ring groove closest to the pin boss more easily than the upper ring groove. Thereby, oil can be efficiently flowed into the oil sump space, and the piston pin can be lubricated and cooled effectively.

  In the third aspect of the invention, the communication passage opens at a plurality of locations dispersed in the circumferential direction of the piston in the ring groove.

  According to the configuration of the third aspect of the present invention, the oil that has entered the ring groove flows into the communication passage from the plurality of openings dispersed in the circumferential direction of the piston in the ring groove and flows into the oil reservoir space. Thereby, oil can be efficiently flowed into the oil sump space, and the piston pin can be lubricated and cooled more effectively.

  In the fourth aspect of the invention, a discharge path for discharging oil from the oil reservoir space is provided.

  According to the configuration of the fourth aspect of the invention, the oil can be retained in the oil sump space while discharging the oil in the oil sump space from the discharge passage so that the amount and time of the oil flowing into the oil sump space become appropriate. . As a result, the oil staying in the oil sump space appropriately flows as the piston moves up and down. As a result, the oil residence time can be appropriately limited to prevent excessive temperature rise.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, an internal combustion engine piston 1 (hereinafter simply referred to as a piston 1) in an embodiment of the present invention is mounted on a cylinder bore 3 of an engine 2. The piston 1 includes a head 4 and a skirt 5 that extends downward from the outer periphery of the head 4.

  As shown in FIG. 2, a plurality of ring grooves 6, 7 arranged in the vertical direction of the piston are provided on the outer peripheral surface side of the head 4. Of the plurality of ring grooves 6, 7, an oil ring 8 is attached to the oil ring groove 7 located on the most piston lower side, and a pressure ring 9 is attached to the other ring grooves 6. A side cut portion 10 is provided inside the skirt 5. A pair of pin bosses 11 are provided on the lower surface side of the head 4. A connecting rod 13 is connected to the pair of pin bosses 11 and 11 via a piston pin 12 inserted into the pin hole 11d. The piston pin 12 is positioned by attaching a retaining ring 15 to a retaining ring groove 21 provided inside the pin boss 11.

  As shown in FIG. 2, the entire circumference of the open end 11 a on the piston outer peripheral surface side of each pin boss 11 is formed in a state positioned near the outermost diameter of the piston so as to be close to the cylinder bore 3. A circular oil reservoir space 14 that is concentric with the pin hole 11 d when viewed in the direction along the pin hole axis of the pin boss 11 is formed inside the end portion 11 b on the piston outer peripheral side of each pin boss 11. The oil sump space 14 faces the end surface 12a and the through hole 12b of the piston pin 12 through the central hole of the retaining ring 15.

  As shown in FIG. 2, each pin boss 11 is provided with a communication passage 16 disposed at an end portion on the side where the opening end 11 a is located. The communication passages 16 of both pin bosses 11 have the same configuration. The communication path 16 of one pin boss 11 is shown in FIGS. The communication path 16 communicates with the oil ring groove 7 closest to the pin boss 11 and the oil sump space 14 among the plurality of ring grooves 6 and 7, and the oil ring groove 7 communicates with the oil sump space 14. Allows the oil to flow. The communication path 16 has a groove shape opened to the outer peripheral surface side of the piston 1.

Thus, when the engine 2 is driven, the piston pins 12 are lubricated and cooled at the end portions of the pin bosses 11.
That is, when the engine 2 is driven and the piston 1 moves downward, the oil ring 8 in the oil ring groove 7 scrapes the oil in the cylinder bore 3 ahead of the pressure ring 9 positioned above the piston with respect to the oil ring 8. Works. The lubricating oil scraped off from the silicon bore 3 flows into the communication path 16 via the oil ring groove 7 and further flows into the oil reservoir space 14. Excess oil that has not flowed into the communication path 16 flows into the oil return hole 19 provided in the oil ring groove 7 and returns to the inside of the piston 1. The entire circumference of the pin boss opening end 11a is close to the cylinder bore 3 by being located near the outermost diameter of the piston. For this reason, the oil that has flowed into the oil reservoir space 14 is unlikely to flow out of the pin boss end opening 11 c and stays in the oil reservoir space 14. The accumulated oil is swayed by the vertical movement of the piston 1 and is easily supplied to the through hole 12 b of the piston pin 12. Further, the oil easily flows into the gap between the pin hole 11d and the piston pin 12 and the oil supply passage 17 provided in the pin hole 11d, and is reliably supplied to the outer peripheral side of the piston pin 12.

FIG. 5 shows the pin boss end of the piston 1 with another implementation structure.
A communication passage 16 that communicates the oil ring groove 7 of the piston 1 with the oil sump space 14 is formed by a through-hole penetrating the pin boss 11.

6 and 7 show the piston 1 having a further communication passage 16.
The communication path 16 here is constituted by a plurality of groove-shaped paths 16a and 16a dispersed in the circumferential direction of the piston.

  As another configuration, the communication path may be configured by a path that branches into a plurality of paths on the oil ring groove 7 side and joins a single path on the oil sump space 14 side. If a plurality of openings are provided on the oil ring groove 7 side in this way to form a communication path, oil can be quickly collected from various parts of the oil ring groove 7 and the oil circulation effect to the pin boss 11 is enhanced. be able to. In particular, if the communication paths are gathered on the oil reservoir space 14 side, the oil can be prevented from flowing back from the pin boss 11 side to the oil ring groove 7 side, and the oil retaining effect can be enhanced. it can.

  As shown in FIGS. 6 and 7, a discharge path 18 may be provided in the pin boss 11 of the piston 1. The discharge path 18 discharges the oil from the oil reservoir chamber 14 at an appropriate discharge amount so that the amount and the residence time of the oil flowing into the oil reservoir space 14 are appropriate. The discharge path 18 is formed by a through hole penetrating the pin boss 11, for example.

  Further, an oil return hole 19 and a dropping oil passage 20 are provided in the oil ring groove 7 of the piston 1. Excess oil in the oil ring groove 7 is returned to the inside of the piston 1 by the oil return hole 19. The dropping oil passage 20 is for dropping excess oil that has not flowed into the communication passage 16 of the oil ring groove 7 to the side cut portion 10 inside the skirt 5. The dropping oil passage 20 is a through hole that does not open to the piston outer peripheral surface side.

[Another Example]
The configuration in which the communication path is provided across the oil ring groove 7 and the oil reservoir space 14 of the pin boss 11 as in the present invention does not include the side cut portion in addition to the piston having the side cut portion 10 as in the above embodiment. The present invention can also be applied to a piston.

Cross section of engine cylinder II-II sectional view of FIG. Oil reservoir space cross section Vertical section of oil sump space Piston oil sump space longitudinal sectional view with another implementation structure Oil reservoir space cross-sectional view of a piston with another implementation structure Oil reservoir space longitudinal section of pin boss with different implementation structure

Explanation of symbols

1 Piston 6 Ring groove 7 Oil ring groove 11 Pin boss 12 Piston pin 14 Oil sump space 16 Communication path 18 Discharge path

Claims (4)

Form the entire circumference of the open end of the pin boss near the outermost diameter of the piston,
An oil sump space formed in a state facing the piston pin in the end portion of the pin boss,
A piston for an internal combustion engine, comprising: a ring groove that is located above the pin boss above the piston and communicates with the oil reservoir space; and a communication passage that allows oil to flow from the ring groove into the oil reservoir space.   2. The internal combustion engine according to claim 1, wherein the communication passage communicates with the oil reservoir space a ring groove closest to the pin boss among a plurality of ring grooves arranged side by side in the piston up-down direction above the pin boss. Piston for engine.   The piston for an internal combustion engine according to claim 1 or 2, wherein the communication path is opened at a plurality of locations dispersed in the circumferential direction of the piston in the ring groove.   The piston for an internal combustion engine according to any one of claims 1 to 3, further comprising a discharge passage for discharging oil from the oil reservoir space.

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