JP3221378B2 - Internal combustion engine piston - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston which reciprocates in a cylinder bore with the combustion of an internal combustion engine, and more particularly to an improvement in a cooling structure of the piston.

[0002]

2. Description of the Related Art As is well known, the piston of an internal combustion engine is
A substantially disk-shaped head portion having a ring groove for mounting a piston ring, a skirt portion provided below the head portion, and provided inside the head portion and the skirt portion, and a piston pin is provided. A pair of pin bosses having a piston pin hole to be inserted and a pin boss rib are provided. Generally, such a piston is required to have a rigidity basically capable of withstanding high-speed motion and thermal deformation and to be lightweight so as to ensure high-speed motion performance.

In this type of piston, the top surface of the head portion forms a part of a combustion chamber, and the piston becomes high temperature under the influence of heat generated in the combustion chamber. And cannot be cooled directly by the outside air. Therefore, conventionally, in order to reduce the temperature, lubricating oil is sprayed onto the inner surface of the piston by an oil jet nozzle or the like, and heat is taken away by the lubricating oil on the inner surface to cool the piston.

[0004]

As described above, although the lubricating oil can be cooled for a while by spraying the lubricating oil,
With the piston structure described above, the exact cooling effect is not always obtained. That is, in the structure of the piston, there is a bias in a portion where the temperature or the stress becomes high, and in particular, a pin boss rib corner portion where the back surface of the head portion and the pin boss rib portion intersect is exposed to a high temperature. Is a part where heat is difficult to escape and is hard to cool, and is a part where various stresses are concentrated.

However, even if the lubricating oil is sprayed on the inner surface of the piston in the above-described manner, the lubricating oil is not always supplied actively to the pin boss rib corners and the like, in particular, to the parts requiring cooling. As a result, the piston cannot be cooled efficiently, for example, the cooling of the portion having a high temperature or high stress is insufficient, or the cooling of the entire piston is uneven.

The present invention has been made in view of such circumstances, and has as its object to provide a cooling structure for more efficiently cooling with lubricating oil and maintain its stable function for a long period of time. It is an object of the present invention to provide a piston of an internal combustion engine that can perform the above.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a substantially disk-shaped head portion having a ring groove in which a piston ring is mounted, and the head portion thereof And a pair of pin boss portions provided inside the head portion and the skirt portion and having a piston pin hole and a pin boss rib portion through which a piston pin is inserted. the a piston for an internal combustion engine reciprocates, the pin
As the stone descends, it is gathered by the skirt
The gist is that a guide groove for selectively guiding lubricating oil to a pin boss rib corner portion where the back surface of the head portion intersects with the pin boss portion is provided on an inner wall surface at a lower end portion of the skirt portion .

According to the first aspect of the present invention, when the piston reciprocating in the cylinder bore descends,
Since the lubricating oil supplied to the skirt is guided to the pin boss rib corner by the guide groove , the lubricating oil surely contacts the pin boss rib corner. Thereafter, the lubricating oil is supplied so as to spread over the entire inner surface of the piston, and at the same time comes into contact with the entire inner surface of the piston. At the portion where the lubricating oil is in contact, heat is taken away by the lubricating oil and thereby cooled. in this way,
Since the lubricating oil is positively supplied to the pin boss rib corner portions having high temperature and high stress, and then entirely supplied to the inner surface, the cooling effect of the piston by the lubricating oil is efficiently increased.

[0009]

[0010]

[0011]

[0012]

[0013]

DETAILED DESCRIPTION OF THE INVENTION hereinafter be described with reference to the form of implementation embodying the present invention with reference to the accompanying drawings.

[0014] Figure 1 (a) is a front view showing the piston 11 in the form of implementation, Fig. 1 (b) is a bottom view of the piston 11 showing the flow of the lubricating oil J is schematically shown.
Also, it is an operation diagram showing a state in which assembled the like piston 11 according to the implementation of the embodiment of FIG 2 Yoko the cylinder bore 12.

As shown in FIGS. 1 (a), 1 (b) and 2, the piston 11 has a substantially disk-shaped head portion 1.
3, a pair of pin bosses 14 provided on the inner wall surface of the head 13, and a skirt 15 provided below the head 13. This piston 11
For example, it is formed of a lightweight metal material such as an aluminum alloy and excellent in thermal conductivity and the like, and has a predetermined rigidity.

Here, three ring grooves 16 extending in the circumferential direction are formed on the outer periphery of the head portion 13.
Each ring groove 16 is provided with a piston ring 17 (FIG. 2). More specifically, the piston ring 17 includes two compression rings 17a, 1
7b and one oil ring 17c. Compression rings 17a and 17b are mounted on the two ring grooves 16 located at the uppermost and central parts, respectively, and an oil ring 17c is mounted on the ring groove 16 located at the lowermost part. The oil return hole 1 is provided in the ring groove 16 in which the oil ring 17c is mounted.
8 (FIG. 1) are provided. The compression rings 17a and 17b are for preventing gas leakage during the compression stroke and the explosion process, and the oil ring 17c is for scraping off excess lubricating oil J adhering to the inner wall surface of the cylinder bore 12. It is.

The pin boss 14 has a piston pin hole 20 and a pin boss rib 21 through which the piston pin 19 (FIG. 2) is inserted. The piston pin 19 is mounted by being inserted into the piston pin hole 20. The pin boss ribs 21 serve to reinforce the pin bosses 14.
On the other hand, the corner where the back surface of the head portion 13 intersects the pin boss portion 14 is a pin boss rib corner portion 22.
It has become. The pin boss rib corner portion 22 is an area where excessive stress is applied and various loads are exposed to high temperatures. The pin boss rib corner 22
Corresponds to the dotted pattern portion shown in each of FIGS. 1 and 2.

Further, the skirt portion 15 is formed as shown in FIG.
Alternatively, as shown in FIG. 2, it is formed to extend downward below the head portion 13. As shown in FIG. 2, the piston 11 configured as described above is connected to a connecting rod 24 connected to a crankshaft 23 which is an output shaft thereof, for example, in an automobile engine.
It is connected via a piston pin 19. In this connection state, the piston 11 is assembled in a cylinder bore 12 provided in the engine, and reciprocates in the cylinder bore 12 during operation of the engine. The oil jet nozzle 25 provided on the connecting rod 24
Oil passage 2 of crankshaft 23 during engine operation
The lubricating oil J, which is fed to the cylinder 6, is injected toward the inner surface of the piston 11 and the inside of the cylinder bore 12.
In this case, the lubricating oil J injected toward the inner surface of the piston 11 is blown upward from below the skirt portion 15. Therefore, in the present embodiment, the following structure is further employed in order to enhance the cooling effect of the piston 11 by the sprayed lubricating oil J.

That is, as shown in FIGS. 1 (a) and 1 (b), in the piston 11 according to the present embodiment, a guide groove 27 as a lubricating oil guide is provided on the inner wall surface of the lower end of the skirt portion 15. Has formed. More specifically, the guide groove 27 is formed in the skirt portion 15 as shown in FIG.
The lubricating oil J is selectively guided to the pin boss rib corner portion 22 as the piston 11 descends, as shown in FIG.

The operation and effect of this embodiment will be described below. In the present embodiment, the guide groove 27 is formed on the inner wall surface at the lower end of the skirt 15 in order to selectively guide the lubricating oil J to the pin boss rib corner 22. Therefore, as shown in FIGS. 1B and 2, when the piston 11 reciprocating in the cylinder bore 12 descends, the piston 11 is gathered by the skirt portion 15 or
The lubricating oil J sprayed by the oil jet nozzle 25 flows in the direction of the arrow along the guide groove 27 and is intensively guided to the pin boss rib corner 22. The lubricating oil J thus guided comes into reliable contact with the pin boss rib corner 22. afterwards,
The lubricating oil J flows so as to spread entirely on the inner surface of the piston 11 and simultaneously contacts the entire inner surface. Then, at the portion where the lubricating oil J contacts, the lubricating oil J
Heat is taken away, and thereby cooled.
As described above, after the lubricating oil J is actively supplied to the pin boss rib corner portions 22 having high temperature and high stress,
Since the entire surface is supplied to the inner surface, the cooling of the piston 11 by the lubricating oil J can be performed very efficiently. The pin boss rib corner 22
Is a portion where various stresses are concentrated and the load exposed to a high temperature is excessive. However, since the pin boss rib corner portion 22 is cooled reliably, the occurrence of cracks due to a decrease in strength is suppressed. You can also.

In the present embodiment, since the pin boss rib corner 22 can be efficiently cooled by the lubricating oil J, it is not necessary to increase the thickness of the head 13 and the like of the piston 11. Therefore, the weight of the piston 11 can be reduced.

[0022]

[0023]

[0024]

[0025]

[0026] The present invention before the present invention is not limited to the form of you facilities can also be other specific forms appropriately without departing from the scope of the invention is carried out as follows.
In-front you facilities mode has four formed a guide groove 2 7 on the inner wall surface of the skirt 1 5, if it can reliably guide the lubricating oil J with respect to the pin boss rib corner portion 22,
The number of the guide grooves 27 is not particularly limited .

[0027]

[0028] - before you facilities embodiment, although the lubricating oil J is guided so as not to intersect with each guide groove 27, intersect on a plane, i.e., so as to guide the lubricating oil J diagonally Is also good. In this case, it is desirable to adjust the angle at which the guide groove is formed so that the lubricating oils J do not actually interfere with each other.

[0029]

[0030] In the - before you facilities of form, three of the ring groove 1
Although it has been embodied in the piston 11 having 6, it may be embodied in a piston having other than three ring grooves. Others
It is those not described 請 Motomeko of the claims,
Technical idea understood from the embodiment above you facilities described in conjunction with the effects below.

[0031]

[0032] - In a piston for an internal combustion engine according to claim 1, wherein the head portion, the skirt portion and the pin boss portion,
It is characterized by being formed of an aluminum alloy.

With this configuration, the weight of the piston can be reduced.

[0034]

According to the first aspect of the present invention, the lubricating oil supplied to the skirt can be reliably guided to the pin boss rib corner by the guide groove . Therefore, the pin boss rib corners can be reliably cooled by the lubricating oil, and the cooling effect of the piston can be efficiently increased.

[0035]

[0036]

[Brief description of the drawings]

Front view and a bottom view showing the FIG. 1 the piston in the form of implementation configurations.

FIG. 2 is an operation view showing a state where the piston and the like according to the embodiment are assembled in a cylinder bore;

[Explanation of symbols]

11: piston, 12: cylinder bore, 13: head, 14: pin boss, 15: skirt, 16: ring groove, 17: piston ring, 17a, 17b: compression ring, 17c: oil ring, 19: piston pin, 20: Piston pin hole, 21: Pin boss rib, 22: Pin boss rib corner, 27: Guide groove as lubricating oil guiding means , J : Lubricating oil.

Claims (1)

(57) [Claims] 1. A substantially disk-shaped head having a ring groove in which a piston ring is mounted, a skirt provided below the head, and provided inside the head and the skirt. A piston pin hole through which a piston pin is inserted, and a pair of pin boss portions having a pin boss rib portion, the piston of the internal combustion engine reciprocating in a cylinder bore, wherein the skirt portion is moved as the piston descends. Collection
Lubricating oil is selectively applied to a pin boss rib corner where the back surface of the head section and the pin boss section intersect.
The piston for an internal combustion engine, characterized in that the guide groove Ke set <br/> the lower end inner wall surface of the skirt portion for guiding.