JPH0949456A - Piston lubricating device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent seizure of a piston generated by an oscillating motion in the vicinity of the bottom dead center of the piston. SOLUTION: An oil jet for injecting piston cooling oil toward a reverse surface of a piston 5 of an internal combustion engine is mounted, a guide surface 8o consisting of a curved surface for guiding the oil, injected to the reverse surface of the piston 5 is formed, to an opposite side to the oil jet, and is formed a protrusion 12 in an internal surface lower side of the piston 5 is formed in an opposite side to the oil jet, and the oil for cooling a top part of the piston to lower down collides against the protrusion 12 so as not to be scattered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston lubrication device for an internal combustion engine, and more particularly to a piston lubrication device for an internal combustion engine that can lubricate a lower end portion of a cylinder particularly at the initial stage of starting the engine. .

[0002]

2. Description of the Related Art A piston of an internal combustion engine reciprocates at a high speed in a cylinder. Therefore, lubricating oil is supplied between the cylinder and the piston to prevent seizure, and in order to cool the piston, An oil jet is attached to the bottom of the cylinder, and oil is jetted to the back of the piston. The state of this oil injection will be described with reference to the conventional example shown in FIG.

In FIG. 2, an oil jet 2 of an internal combustion engine 1 is attached to the lower end of a cylinder body 3, and an injection nozzle 4 directed upwards injects oil 6 toward the back side of a piston 5 to cause the piston 5 to move. Cooling from the back side.
Then, the back surface 8 of the piston 5 is usually formed in a circular shape so that the injected oil 6 reaches the opposite side of the piston pin 7. When formed in this way, the oil can move the back side of the piston in the direction of the arrow to cool the top of the piston 5. Reference numeral 9 shown in FIG. 2 is an oil gallery.

Therefore, on the crank chamber 10 side of the engine, the oil descending from the piston 5 and the cylinder 11 is splashed by a crank (not shown) or the like, and the oil mist is filled during engine operation.

[0005]

By the way, as shown in FIG. 2, since the piston 5 is axially supported by the piston pin 7 and is supported from below by a connecting rod and a crank (both not shown), the bottom of the piston 5 is not supported. At the dead point portion, the sliding force is applied while being alternately and strongly pressed against the portion A of the cylinder 11 (the portion shown by hatching in FIG. 2) which is orthogonal to the piston pin 7.

However, conventionally, there is no means for supplying lubricating oil to this portion, and since the oil mist is not sufficiently generated at the initial stage of engine start, a high-quality cylinder liner is adopted or a cylinder liner is used. If the surface treatment is not performed, there is a problem that the piston 4 may seize near the bottom dead center. The present invention
The present invention has been made in view of the above problems, and an object of the invention is to provide a piston lubrication device for an internal combustion engine, which prevents the seizure of the piston that occurs near the bottom dead center.

[0007]

A means for a piston lubrication device for an internal combustion engine according to the present invention for solving the above-mentioned problems is an oil jet for injecting oil for cooling the piston toward the back side of the piston of the internal combustion engine. A guide surface consisting of a curved surface that guides the oil injected on the back surface of the piston to the opposite side of the piston, is formed on the back side of the piston, and projects toward the inside of the piston on the lower side of the piston inner surface on the opposite side. A shelf-like projection is provided so that the oil that cools the top of the piston and descends hits the projection and is scattered.

The shape of the guide surface may be appropriately determined in accordance with actual conditions and is not particularly limited, but may be, for example, a circular cross section. It is preferable that the protrusion having the above-described structure is provided at a portion where the largest amount of the oil flow that cools the piston from the back side and descends passes. When the engine operates, the piston violently moves up and down even at the time of starting with a low rotation speed, and air, blow-by gas and the like in this portion are vigorously stirred. Therefore, the oil descending along the back surface of the piston violently hits the projections and scatters to become a mist.
The oil mist floats while being entrained in the air current such as the air or blow-by gas.

Therefore, even if the engine is stopped and the portion A at the lower end of the cylinder is dry, the oil mist generated by the oil flow colliding with the protrusions immediately after the engine starts to prevent the piston from seizing. it can.
The means for forming the protrusion is not particularly limited, but it is generally preferable to integrally form it when casting the piston. However, the present invention is not limited to this and may be formed by any means.

[0010]

Embodiments of the present invention will be described in detail with reference to the accompanying drawings. The piston 5 shown in FIGS. 1A and 1B is mounted on the same engine as the conventional internal combustion engine 1 shown in FIG. 2 to carry out the present invention. Therefore, overlapping drawings are omitted, and the same members as those in FIG.

[0011] In FIG. 1, the cross-sectional shape on the back side of the piston 5 forms a guide surface 8 ₀ of the circular, the oil jet (not shown) opposite the piston inner surface lower end portion to the shelf-like of (the right side in the figure) The protrusion 12 is formed. Next, the operation of the present piston lubrication device will be described. Oil 6 injected from oil jet strikes a region P of the guide surface 8 _0, momentum along the guide surface 8 ₀ opposite (right of the figure, the direction of the arrow F) the piston crown and cooled while being guided by the , Falls on the inner surface of the opposite side piston 5, hits the projection 12 and scatters as oil mist.

The scattered oil mist m is entrained by the turbulent flow produced by the reciprocating motion of the piston 5 and is suspended and adheres to the surrounding wall surface. Since this oil mist m can be already generated at the beginning of engine start, a part of the oil mist also adheres to part A (FIG. 2) from the beginning of engine start and lubricates this part to prevent piston seizure. can do.

[0013]

As described above, the piston lubrication device for an internal combustion engine of the present invention injects oil toward the guide surface formed on the back surface of the piston, and the piston on the side opposite to the injection position is provided with a projection on the lower side of the inner surface. Since the oil has been formed, the cooling-finished oil hits the projections and scatters to form an oil mist. This oil mist is generated from the initial stage of engine start and adheres to the surrounding wall surface.Therefore, it is possible to prevent the seizure of the piston caused by the lack of oil adhering to the cylinder near the bottom dead center and to improve the reliability of the internal combustion engine. it can.

[Brief description of drawings]

FIG. 1A is a vertical cross-sectional view of a piston portion of a piston lubrication device for an internal combustion engine of the present embodiment, and B is a bottom view of the piston.

FIG. 2 is a longitudinal sectional view of an essential part of an engine for explaining the problems of the conventional internal combustion engine.

[Explanation of symbols]

1 Internal Combustion Engine 2 Oil Jet 3 Cylinder Body 4 Injection Nozzle 5 Piston 6 Oil Jet 8 Back Side 8 ₀ Guide Surface 11 Cylinder 12 Protrusion

Claims (1)

[Claims] 1. An internal combustion engine is provided with an oil jet for injecting oil for cooling the piston toward the back side of the piston, and a guide surface formed of a curved surface for guiding the injected oil to the opposite side of the piston is provided on the back side of the piston. It is formed on the back side of the piston, and on the lower side of the inner surface of the piston on the opposite side, a shelf-like protrusion that protrudes toward the inside of the piston is provided, and the oil that cools down the top of the piston hits the protrusion and is scattered. Piston lubrication device for internal combustion engine.