JP2539327Y2 - Piston for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a piston for an internal combustion engine, and more particularly to an improved piston for an internal combustion engine with respect to piston cooling by oil.

[Prior Art] A piston used in an internal combustion engine generally has a cup shape having a top portion and a cylindrical skirt portion provided to be connected to an outer peripheral edge thereof, and the skirt portion slides on an inner peripheral surface of a cylinder bore. In order to reduce the resistance and reduce the weight, a pair of side cut portions recessed from the outer peripheral surface of the piston are provided around the open end of the piston pin hole opened in the outer peripheral surface of the piston. This type of piston is disclosed, for example, in JP-A-62-85152.

In this type of piston, the oil ring penetrates through the piston base material between the oil ring groove and the side cut part in order to quickly drain the oil that has been scraped from the cylinder bore wall surface and flows into the oil ring groove. It is disclosed in Japanese Utility Model Laid-Open Publication No. 53-147310 that a newly formed oil escape hole is provided.

[Problem to be Solved by the Invention] When the oil escape hole is provided as described above, the oil in the oil ring groove is quickly discharged toward the side cut portion, but this oil remains in the side cut portion. The piston makes a repetitive jumping motion in the side cut portion with the vertical movement of the piston, and only increases the inertial mass of the piston, and does not contribute to effective cooling of the piston.

A hole that extends diagonally from the upper edge of the side cut portion toward the piston internal space so as to cross a part of the bottom of the oil ring groove is formed, and the oil ring groove, the side cut portion, and the piston internal space are formed by the oblique hole. Is disclosed in Japanese Utility Model Laid-Open No. 63-34342.
Although the provision of such oblique holes simultaneously reduces the mass of the piston and achieves a reduction in the weight of the piston, there is a possibility that the piston may be weakened.

Japanese Utility Model Application Laid-Open No. 60-120242 discloses a piston structure in which a hole is made through the piston base material between the bottom of the oil ring groove and the piston internal space, and the oil ring groove communicates with the piston internal space. Have been.

According to the present invention, a hole is formed through the piston base material between the oil ring groove and the side cut portion as described above, and the piston base material is formed between the bottom of the oil ring groove and the piston internal space. Effective use of the drilled holes and the use of reversal of the inertial force acting on the oil as the piston reciprocates, without impairing the strength of the piston as much as possible. Once collected from the groove to the side cut section, the oil collected in the side cut section is allowed to flow further into the piston internal space, and thus the contact between the oil and the piston base material is further increased, thereby cooling the piston by oil. It is an object of the present invention to provide an improved piston for an internal combustion engine so as to perform better.

Means for Solving the Problems According to the present invention, the object as described above is for an internal combustion engine having a side cut portion recessed from the piston outer peripheral surface around the open end of a piston pin hole opened in the piston outer peripheral surface. In the piston, an oil ring groove provided on the outer peripheral portion of the piston and the side cut portion are connected to communicate with each other, and the piston is blanked through a piston base material between the oil ring groove and the side cut portion. A first oil passage, a second oil passage penetrating through a piston base material between a bottom of the oil ring groove and a piston internal space, and the first oil passage and the second oil passage; The second oil passage is aligned with the second oil passage at the same position as viewed in the circumferential direction of the oil ring groove, and moves from the oil ring groove to the first oil with the movement of the piston from the bottom dead center to the top dead center. A flow of oil toward the side cut portion occurs through the oil passage, and the first oil passage and the second oil passage are moved from the side cut portion with the movement of the piston from the top dead center to the bottom dead center. This is achieved by a piston for an internal combustion engine, which is configured to generate a flow of oil toward the internal space of the piston.

[Operation and Effect of the Invention] According to the above-described configuration, in the process of moving the piston from the bottom dead center to the top dead center, the oil scraped off by the oil ring and flowing into the oil ring groove acts on the oil ring. Due to the inertial force, the oil flows into the side cut section via the first oil passage, and while the piston moves from the top dead center to the bottom dead center, the oil flowing to the side cut section is acted upon by the inertia force acting in the opposite direction. The oil flows from the side cut portion to the oil ring groove through the first oil passage in the reverse direction, and further flows into the piston internal space via the second oil passage which is opened while being urged by the inertia force and aligned therewith. The effect of cooling the internal space of the piston, especially the ceiling wall, can be achieved by the combination of the short holes individually drilled in the piston base material without substantially affecting the strength of the piston. Wear. Incidentally, as described in the above-mentioned Japanese Utility Model Publication No. 63-34342,
Forming a large hole for oil to escape from the oil ring groove to reduce the weight of the piston is one technical insight.However, if you want to reduce the weight of the piston, avoid local stress concentration as much as possible. It is much more effective to reduce the overall wall thickness, and it is considered that making a large hole in a part of the piston wall causes stress concentration and is not always effective in relation to strength.

[Embodiment] The present invention will be described in detail below with reference to the accompanying drawings.

1 to 4 show one embodiment of a piston for an internal combustion engine according to the present invention. In the drawing, reference numeral 10 denotes a piston as a whole, and the piston 10 has a disc-shaped piston top 12 and a cylindrical skirt 14 provided to be connected to the outer peripheral edge of the piston top 12. , In the shape of a cup. The outer periphery of the piston top 12 has three ring grooves, namely two piston ring grooves 16 and 18 and one oil ring groove.
20 are provided respectively. A piston ring (not shown) is mounted on the piston ring grooves 16 and 18, and an oil ring 22 is mounted on the oil ring groove 20, as shown in FIG. 3 or FIG. I have.

The skirt portion 14 is provided with a pair of piston pin holes 24 opened on the outer peripheral surface of the piston. Around the open end of the piston pin hole 24, there is provided a side cut portion 26 which is recessed from the outer peripheral surface of the piston.

A first oil passage which penetrates a piston base material constituting the partition and communicates and connects the oil ring groove 20 and the side cut portion 26 to a shelf-shaped partition 28 separating the oil ring groove 20 and the side cut portion 26. 30 have been opened. The first oil passage 30 opens at one end into the back of the oil ring groove 20, and opens at the other end at the upper end of the side cut portion 26, and a piston is provided in each of the pair of side cuts 26. One pin is provided on each side of the pin hole 24.

A second oil passage 34, which is circumferentially aligned with the first oil passage 30 and communicates and connects the oil ring groove 20 and the piston internal space 32, is opened through the piston base material separating them. Since the oil passages 30 and 34 are aligned with each other when viewed in the circumferential direction of the oil ring groove, an oil passage that effectively acts to connect the side cut portion 26 to the piston internal space 32 is formed.

The oil passage 34 is smaller than the groove width of the oil ring groove 20, so that the oil ring groove 20 has the back wall 21 left in the portion where the oil passage 34 is provided.

With the above-described configuration, when the piston is lifted, that is, when the piston moves from the bottom dead center to the top dead center, the oil scraped from the cylinder bore wall surface by the oil ring 22 does not act on the oil. As shown by an arrow in FIG. 3, the oil flows into the oil ring groove 20 by the force, and further flows through the first oil passage 30 to the side cut portion 26 by the inertial force acting on the oil. Part of the oil that has flowed into the oil ring groove 20 passes through the second oil passage 34 when the piston rises, and
32, the oil passage 34 is narrower than the oil ring groove 20, and the back wall 21 of the oil ring groove 20 remains in the portion where the oil passage 34 is provided.
The oil collides with the inner wall 21. At this time, almost no run-up due to inertial force has occurred in the oil at this time, so that most of the oil flows to the side cut portion 26. As a result, oil is accumulated in the side cut portion 26 when the piston is raised.

When the piston descends, that is, when it moves from the top dead center to the bottom dead center, the oil stored in the side cut portion 26 jumps up due to the inertial force, flows through the oil passage 30 with a relatively fast flow velocity due to sufficient approach, and reaches the outlet thereof. Since the passage 34 is exactly aligned, the oil further passes through the passage 34 to the piston internal space 32, flows along the ceiling surface 33, and drops freely therefrom. As a result, the piston top 12, which becomes particularly hot due to the combustion heat, is cooled well.

If the piston top 12 is cooled well, the piston
10 The temperature rise of the whole is suppressed, the thermal deformation of the piston due to thermal expansion is suppressed, the seizure of the piston is avoided, the scuff and friction are reduced, and the initial bore clearance can be reduced accordingly. The slap sound at low temperature and low speed is reduced.

The first oil passage 30 and the second oil passage 34 are provided with as much oil as possible depending on the amount of oil pooled in the side cut portion 26, the behavior of oil in the side cut portion during reciprocation of the piston, and the like. The size, the position, the extending direction, and the like of each other may be appropriately determined so that the oil is temporarily accumulated in the side cut portion from the oil ring groove 20 and then flows into the piston internal space.

If the oil passage 34 is narrowed, the piston ring moves through the oil ring groove 20 through the passage when the piston is lifted.
Regarding piston top cooling to 32, while the flow rate of oil flowing wastefully decreases, the flow rate of oil flowing from this passage to the piston internal space 32 when the piston descends increases,
The oil can be blown off to the ceiling wall 33 at a portion distant from the passage, and the entire ceiling surface is cooled.

[Brief description of the drawings]

1 is a front view showing one embodiment of a piston for an internal combustion engine according to the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIGS. 3 and 4 are internal combustion engines according to the present invention. It is sectional drawing which expands and shows the principal part of the piston for engines. 10 ... Piston, 12 ... Piston top, 14 ... Skirt, 16,18 ... Piston ring groove, 20 ... Oil ring groove, 21 ... Back wall, 22 ... Oil ring, 24 ... Piston pin Hole, 26 ... Side cut portion, 28 ... Partition wall, 30 ... First oil passage, 32 ... Piston internal space, 34 ... Second oil passage

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References Practical application Microfilm (JP, U) photographing the contents of the specification and drawings attached to the application form of Japanese Application No. 61-127545 (Japanese Utility Model Application No. 63-34342). Microfilm (JP, U) photographing the contents of the specification and drawings attached to the application for Japanese Patent Application No. 52-52743 (Japanese Utility Model Application No. 53-147310) Japanese Utility Model Application No. 59-7908 (Japanese Utility Model Application No. 60-120242) (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] 1. A piston for an internal combustion engine having a side cut portion (26) recessed from the piston outer peripheral surface around an open end of a piston pin hole (24) opened in the piston outer peripheral surface.
A piston base material between the oil ring groove (20) and the side cut portion (26) for connecting and connecting the oil ring groove (20) provided on the outer periphery of the piston and the side cut portion (26). And a second oil passage penetrated through a piston base material between the bottom of the oil ring groove (20) and the piston internal space (32). Oil passage (34), and the first oil passage (30) and the second oil passage (34) are aligned at the same position as viewed in the circumferential direction of the oil ring groove (20). With the movement of the piston from the bottom dead center to the top dead center, the flow of oil from the oil ring groove (20) to the side cut portion (26) via the first oil passage (30) is reduced. And the piston moves from top dead center to bottom dead center. The first oil passage (30) and the second oil passage (34) from the cut portion (26)
A piston for an internal combustion engine is configured to generate a flow of oil toward the piston internal space (32) through the piston.