KR20140023602A - Piston having cylindrical rotating structure for improved cooling ability of oil gallery - Google Patents

Abstract

An object of the present invention to maximize the heat transfer efficiency of the existing oil gallery, to improve the fuel economy through the reduction of oil pumping loss according to the reduction of the oil flow rate to provide a piston with improved skirt cooling and conrod lubricity.
To this end, the present invention is in the piston having an oil inlet structure for guiding the oil gallery through which the oil passes through is formed in an annular shape, the oil injected from the oil injection nozzle is introduced into the oil gallery through the oil inlet The inner circumferential surface of the oil inlet structure is formed with a gradient such that its diameter increases toward the opening end of the oil injection nozzle side, and the outer circumferential surface of the oil inlet structure is rotatably connected to the piston about the central axis of the oil inlet. It is done.

Description

PISTON HAVING CYLINDRICAL ROTATING STRUCTURE FOR IMPROVED COOLING ABILITY OF OIL GALLERY}

The present invention relates to a piston of an internal combustion engine, and more particularly, an oil gallery through which oil passes is formed in an annular shape, and guides the oil injected from the oil injection nozzle to flow into the oil gallery through the oil inlet. An oil inlet structure is rotatably connected to an oil inlet to improve the flowability of oil.

The piston is a mechanism that reciprocates in the cylinder and receives the gas pressure of high temperature and high pressure in the expansion stroke and applies it to the crankshaft through the connecting rod.The piston head is exposed to high temperature combustion gas of 2000 ℃ or higher, and 140 ~ 160kg / In addition to being shocked in a short time in cm ^3, the cylinder moves at high speeds, creating strong friction with the cylinder walls.

In addition, the piston needs to be cooled to prevent thermal sintering due to high temperature while the piston ring interposed on the upper outer circumferential surface of the piston in contact with the cylinder wall in consideration of thermal expansion.

Accordingly, an annular oil gallery 11 is illustrated in FIG. 4 for preventing damage to the piston due to high heat of combustion and cooling inside the piston in the combustion process of the fuel, which is disclosed in the patent application filed by the present applicant. It is one of the accompanying drawings described in Unexamined-Japanese-Patent No. 2004-0005201 (2004.1.16). As shown in FIG. 4, the oil gallery 11 is formed inside the body of the piston 10, that is, inside the ring carrier 13 into which the piston ring 12 is fitted. That is, the oil is ejected through the oil injection nozzle installed in the cylinder block or the like during operation of the engine, and a part of the ejected oil flows into the oil gallery 11, and then circulates into the oil gallery 11. While cooling the body and the ring carrier 13 of the piston 10 is discharged through the oil outlet (15).

On the other hand, the oil gallery 11 is generally formed in an annular shape inside the body of the piston 10 through a weight loss process by the sand core in the casting process of the piston 10, the annular oil gallery 11 One side of the oil inlet 14 for the oil is introduced is formed and the other side is the oil outlet 15 is formed. In general, the oil inlet 14 and the oil outlet 15 are formed opposite each other at 180 degree intervals.

Therefore, oil injected at high pressure from the oil injection nozzle provided on the cylinder block side is input to the oil gallery 15 through the oil inlet 14 described above to cool the upper end of the piston 10, and then the oil outlet described above. It is returned to the crank seal via (1).

In the cooling structure of such a piston, a configuration is known in which an oil inlet structure is provided at the oil inlet so that oil is sufficiently applied to the oil gallery. The oil inlet structures which guide the oil injected from the oil spray nozzle into the oil gallery are formed in the inner wall of the cylinder, elliptical or venturi nozzle.

However, even with such oil inlet structures, there is a problem in that the oil is not sufficiently filled in the oil gallery and thus the piston is not sufficiently cooled by the oil gallery, and the shape of the oil inlet structure is complicated.

Patent Publication No. 2004-0005201

The present invention solves the technical problems of the conventional oil gallery for cooling the piston, and maximizes the heat transfer efficiency of the existing oil gallery, the fuel economy is improved by reducing the oil pumping loss according to the oil flow rate reduced, skirt cooling and cone The purpose is to provide a piston with improved rod lubricity.

The present invention to achieve the above object,

(1) A piston having an oil gallery through which an oil passes is formed in an annular shape, and having an oil inlet structure for guiding oil injected from an oil injection nozzle into the oil gallery through an oil inlet,

The oil inlet structure is a cylindrical structure, characterized in that the gradient is formed such that the diameter of the oil inlet structure is rotatably connected to the oil inlet and the inner circumferential surface of the oil inlet structure increases toward the opening end of the oil injection nozzle side. It is characterized by. Through this, the rotational force of the oil inlet structure is changed according to the injection speed of the oil passing through the oil inlet structure to improve the filling power of the oil filled in the oil gallery to maximize the cooling efficiency.

(2) The oil inlet structure is preferably rotatably supported by a needle bearing installed at the oil inlet.

(3) It is preferable that a plurality of oil guide protrusions protrude from the inner circumferential surface of the oil inlet structure.

(4) The oil guide protrusion is preferably repeatedly formed to form a spiral in the longitudinal direction, so that a spiral flow path is formed between the oil guide protrusions.

(5) It is preferable that the said oil guide protrusion protrudes perpendicularly with respect to the longitudinal direction of a structure from the inner peripheral surface of an oil inlet structure.

The present invention maximizes the heat transfer efficiency of the existing oil gallery by improving the oil filling rate inside the oil gallery, so that the fuel economy is improved by reducing the oil pumping loss according to the reduced oil flow rate and the skirt cooling and the cone rod lubricity is improved. It is effective.

1 is a front sectional view of a piston according to the present invention;
2 is a front sectional view of an oil inlet structure of a piston according to the present invention;
3 is a perspective view of an oil inlet structure of a piston according to the invention
Figure 4 is a view showing a piston formed with a conventional oil gallery

The present invention will now be described in detail with reference to the accompanying drawings. Hereinafter, a repeated description, a known function that may obscure the gist of the present invention, and a detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

Hereinafter, a variable valve apparatus for a muffler according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, in which parts identical to those of the prior art are denoted by the same reference numerals, and are referred to FIG. 6 and FIG.

1 is a front sectional view of a piston constructed by the present invention and a cooling device thereof.

Reference numeral 20 denoted in the drawing indicates a piston according to the present invention, and a ring groove 21 for fitting a piston ring is formed on an upper outer circumferential surface of the piston 20.

In addition, an oil gallery 22 for cooling the upper end of the piston 20 exposed to high heat is formed in an annular shape inside the ring groove 21, and oil injection is performed at one lower portion of the oil gallery 22. An oil inlet 23 is formed through which oil injected from the nozzle 24 passes. In addition, an oil outlet (not shown) is formed for the oil flowing in the oil inlet 23 to circulate the oil gallery and cool the piston 20 and then return to the crankcase side again.

An oil spray nozzle 24 is provided at a position corresponding to the lower portion of the oil inlet 23 of the cylinder block 25. The oil injection nozzle 24 serves to inject the pumped oil from the oil pump (not shown) to the oil inlet under the piston.

The oil inlet 23 formed at one lower portion of the oil gallery 22 has a cylindrical oil inlet structure 30 for guiding oil injected from the oil injection nozzle 24 into the oil gallery 22. It is rotatably connected about the central axis of the inlet (23).

2 shows an oil inlet structure according to the invention. According to FIG. 2, the oil inlet structure 30 is composed of a discharge port 31 and a body portion 32, and the inner wall of the body portion 32 has a tapered shape at a predetermined angle. Accordingly, the inner circumferential surface of the oil inlet structure 30 is formed with a gradient whose diameter increases toward the opening end 34 of the oil inlet structure 30 toward the oil injection nozzle 24, so that the oil injection nozzle 24 is formed. Effectively capture the oil injected from the.

The discharge port 31 is formed to extend from the body portion, one end of the discharge port 31 is in contact with the lower end of the body portion 32, the other end of the discharge port 31 is in contact with the inner surface of the oil gallery (22). The discharge port 31 may have a cylindrical shape having a constant diameter, and the oil inlet structure 30 may be rotatably inserted with respect to the central axis 28 of the oil inlet 23.

According to FIG. 2, the needle roller bearing 26 is built in the oil inlet 23 side, and the outer peripheral part of the discharge port 31 of the oil inlet structure 30 is axially rotated so that a relative rotation with the piston 20 is possible. In this way, the oil inlet structure 30 is rotatably connected with the piston 20 about the central axis 28 of the oil inlet 23. Thus, the oil inlet structure 30 is rotated by the oil injected by the oil injection nozzle 24 collides with the inner circumferential surface of the oil inlet structure 30.

2 also shows an oil inlet structure 30 according to another preferred embodiment of the present invention. 2, a plurality of oil guide protrusions 35 and the like protrude from the discharge port 31 of the oil inlet structure 30 and the inner circumferential surface 33 of the body portion 32 in the longitudinal direction. 35 forms a flow path for inducing the flow of oil on the inner circumferential surface 33 of the oil inlet structure 30 with the oil injected from the oil injection nozzle 24.

According to a preferred embodiment of the invention shown in FIG. 2, the oil guide protrusion 35 protrudes perpendicularly to the longitudinal direction of the oil inlet structure 30 from the inner circumferential surface 33 of the oil inlet structure 30. . Through this, the induction of oil by the oil guide protrusion 35 and the induction of rotation of the oil inlet structure 30 due to the collision between the oil and the inner circumferential surface 33 of the oil inlet structure 30 may be easily generated. .

According to a preferred embodiment of the present invention shown in Figure 3, the oil guide projection 35 may be formed repeatedly to form a spiral in the longitudinal direction. As a result, a spiral flow path 36 is formed between the oil guide protrusions 35, so that the flow of oil along the inner circumferential surface of the oil inlet structure 30 is accelerated, and the rotational speed of the oil inlet structure 30 is also increased. Done.

Referring to the operation of the cooling structure of the piston according to the present invention configured as described above are as follows.

When the engine is started, oil is pumped to cool or lubricate the sliding and frictional portions of the engine. Oil popped from the oil pump is transferred to each device, and some oil for cooling the piston is injected through the oil injection nozzle 24 to the bottom of the piston 20.

Oil injected from the oil injection nozzle is guided from the oil inlet 23 through the oil inlet structure 30 into the interior of the oil gallery 22 to cool the interior of the piston. The oil circulated through the oil gallery 22 is discharged to the oil outlet.

According to the present invention, the oil 27 injected from the oil injection nozzle 24 collides with the inner circumferential surface 33 of the oil inlet structure 30 to induce rotation of the oil inlet structure 30. Rotation of the oil inlet structure 30 imparts a strong momentum to the oil passing through the oil inlet structure 30, thereby enabling a better distribution of the oil upon outflow into the oil gallery 22, and thus oil gallery (22) The oil filling rate inside is increased. Thus, a good cooling effect can be achieved even with a minimum oil supply.

In addition, a plurality of oil guide protrusions 35 protrude from the inner circumferential surface 33 of the oil inlet structure 30 of the present invention, so that the oil 27 injected from the oil injection nozzle 24 is the oil inlet structure 30. The flow of oil is induced along the inner circumferential surface 33 of (). In particular, according to a preferred embodiment of the present invention, the oil guide protrusion 35 is formed repeatedly to form a spiral in the longitudinal direction, is configured to form a spiral flow path between the oil guide protrusion 35, the injection of oil The rotational force of the oil guiding protrusion 35 is doubled according to the speed, so that the oil can be sufficiently applied to the inside of the oil gallery 22, thereby achieving an excellent cooling effect even with a minimum oil supply.

20: piston 21: ring groove
22: Oil Gallery 23: Oil Inlet
24: nozzle 25: cylinder block
26: needle roller bearing 27: oil
28: central axis of oil inlet 30: oil inlet structure
31: discharge port 32: body portion
33: inner circumferential surface 34: opening end
35: oil guide projection 36: spiral flow path

Claims (5)

An oil gallery through which oil passes is formed in an annular shape, and a piston having an oil inlet structure for guiding oil injected from an oil injection nozzle to enter the oil gallery through an oil inlet,
The inner circumferential surface of the oil inlet structure is formed such that its diameter increases toward the opening end on the side of the oil injection nozzle,
And an outer circumferential surface of the oil inlet structure is connected to the piston to be rotatable about a central axis of the oil inlet. The method according to claim 1,
And the oil inlet structure is rotatably axially supported by a needle roller bearing installed at the oil inlet. The method according to claim 1 or 2
A piston, characterized in that the inner circumferential surface of the oil inlet structure protrudes a plurality of oil guide projections. The method according to claim 3,
The oil guide protrusion is formed to form a spiral in the longitudinal direction of the structure, the piston, characterized in that configured to form a spiral flow path between the oil guide protrusion. The method according to claim 3,
And the oil guide protrusion protrudes from the inner circumferential surface of the oil inlet structure perpendicularly to the longitudinal direction of the structure.

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