JPS6315560Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a piston cooling device for internal combustion engines, etc., and more specifically, a piston cooling device that sprays cooling oil on the inner lower surface of the top surface of the piston. Regarding the improvement of

(Prior Art) The piston of an internal combustion engine is exposed to high temperature combustion gas and is therefore subjected to a large thermal load.
For this reason, various cooling methods are employed for the pistons of internal combustion engines.

One of the conventionally known piston cooling methods for internal combustion engines involves injecting lubricating oil onto the inner lower surface of the piston.

This conventionally known piston cooling device will be explained with reference to FIGS. 1 to 4.

In the conventional piston cooling device,
As shown in the figure, oil was injected from a cooling oil injection nozzle 1 attached to the engine body toward an injection target surface 3 formed on a curved surface of the inner peripheral edge near the top surface of a piston 2.

In addition, in FIGS. 1 and 2, P is a piston pin and B is a boss for inserting the piston pin, but a description thereof will be omitted.

(Problems to be solved by the invention) However, the above-mentioned conventional technology has the following problems.

The cooling oil is injected toward the injection target surface 3 , and after colliding with the injection target surface 3 , the cooling oil changes direction and flows toward the center 5 of the top surface 4 of the piston 2 . Depending on the inclination angle at which the injected oil collides with the injected surface 3 (the angle at which the tangent at that point intersects the cylinder axis line), most of the collided injected oil will head toward the center 5 of the top surface 4 of the piston 2. Therefore, in order for most of the colliding injected oil to go toward the center 5 of the top surface 4 of the piston 2, the inclination angle of the colliding surface must be 45 degrees or less. Although the oil is injected toward a predetermined point on the injection target surface 3, the collision point of the injected oil may shift depending on the installation accuracy of the oil injection nozzle 1. If the injection target surface 3 is a curved surface, even if the collision point is slightly shifted, its inclination angle will change to 45 degrees or more. In this way, as the angle of inclination exceeds 45° and approaches 90°, the oil injected there tends to disperse in various directions a, c, and d, as shown in Figure 3. As a result, the amount of oil flowing toward the direction e of the center 5 of the piston top surface 4, which requires cooling, tends to decrease.

In addition, as shown in Fig. 4, the deviation of the collision point of the injected oil is determined by the axis 6 of the oil injection nozzle 1 (direction of the injected oil).
may not be completely parallel to the cylinder axis 7. That is, as the piston 2 strokes, the collision point within the piston 2 shifts, so even if there is a slight installation error of the oil injection nozzle 1, the collision point of the injected oil within the piston 2 shifts, and as a result,
The amount of cooling oil directed toward the piston top surface 4 was often unstable (not a constant amount).

SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an improved piston cooling device which eliminates the above-mentioned drawbacks and does not cause insufficient cooling of the back side of the piston top surface.

(Means for solving the problem) In order to achieve the above object, oil is injected into the inside of the piston from the skirt side of the piston by an oil injection nozzle, and the direction of the oil injected from the injection nozzle is aligned with the cylinder axis. In a piston cooling device of the type parallel to the piston, a guide surface for directing the direction of the oil injected from the oil injection nozzle toward the top surface of the piston is provided near the top surface of the inner peripheral edge of the piston, and the guide surface is provided near the top surface of the inner peripheral edge of the piston. The surface is configured as a flat surface that is inclined at an angle θ (θ: about 45°) with respect to the top surface of the piston and at an angle (90°−θ) with respect to the cylinder axis.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 5 to 8.

As shown in FIG. 5, the piston 8 improved according to the present invention has an inclined guide surface 11 in order to change the direction of the oil injected from the oil injection nozzle 1 toward the center 10 of the top surface 9 of the piston. It is provided. As shown in FIG. 6, this guide surface 11 is inclined at an angle .theta. with respect to the piston top surface 9 and at an angle (90.degree.-.theta.) with respect to the cylinder axis 7. Here, the angle θ is preferably set to 45° or less, but if the inclination is too strong, the impact area (projected area) of the injected oil will be reduced, so it is actually desirable to set it to about 45°. Moreover, this guide surface 11 is a flat surface (that is, as shown in FIGS. 5 and 6).
In the figure, it is configured as a plane perpendicular to the plane of the paper.

Since the present invention is constructed as described above, the oil injected from the oil injection nozzle 1 onto the guide surface 11 is converted into a flow having a vector in the direction of arrow A in FIG. 6 after colliding with the guide surface 11. , the guide surface 11 is at an angle θ
Therefore, there is little flow in the direction perpendicular to the plane of the paper in FIG. 6, and almost no flow in the direction opposite to arrow A.

In the present invention, even if the collision point of the injected oil shifts due to nozzle installation accuracy, etc., the area of the guide surface 11 is made wide enough to absorb the shift, so that the collision angle of the injected oil is always kept constant. It becomes something that can be done. Therefore, there is little variation in the amount of oil flowing toward the center 10 of the top surface of the piston.
As a result, the amount of oil flowing toward the center 10 of the piston becomes constant, and there is no fear that the top surface 9 of the piston will be insufficiently cooled.

Further, the deviation of the collision point of the injected oil is within a substantially circular range centered on the designed set point. In the present invention, by making the guide surface a flat surface within that range, the collision angle of the injected oil is always constant, and fluctuations in the cooling effect can be reduced as much as possible.

In order to strengthen the directivity of the oil toward the center 10 of the piston top surface 9, guide rails R are provided along both side edges of the guide surface 11 as shown in FIG. 7, or as shown in FIG. Guide surface 11 as shown
A groove g may be provided parallel to arrow A (FIG. 6).

Further, the guide surface 11 may be integrally molded as a part of the piston 8, but it may also be molded into a small piece separate from the piston 8 and the small piece attached to the piston.

(Effects of the invention) According to the invention, even if there are variations in the collision point of the injected oil due to the nozzle installation accuracy, etc.
Fluctuations in the amount of cooling oil flowing toward the center of the piston can be reduced, eliminating the risk of insufficient cooling of the top surface of the piston.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of half a piston in a conventional piston cooling device. FIG. 2 is a plan view of FIG. 1. FIGS. 3 and 4 are explanatory diagrams for explaining the drawbacks of the prior art. FIG. 5 is a half longitudinal sectional view of an embodiment of the present invention. FIG. 6 is a partially enlarged explanatory diagram of FIG. 5. FIG. 7 and FIG. 8 are diagrams showing other embodiments, and FIG.
It is a view seen from direction C in the figure. 1: Oil injection nozzle, 2: Piston, 7: Cylinder axis, 8: Piston, 9: Piston top surface, 1
1: Information surface.

Claims (1)

[Claims for Utility Model Registration] A piston cooling device in which oil is injected into the inside of the piston from the skirt side of the piston by an oil injection nozzle, and the direction of the oil injected from the injection nozzle is parallel to the cylinder axis. A guide surface for directing the direction of the oil injected from the oil injection nozzle toward the top surface of the piston is provided near the top surface of the inner peripheral edge of the piston, and the guide surface is directed toward the top surface of the piston. It is tilted by an angle θ (θ: about 45°) and (90° - θ) with respect to the cylinder axis.
A piston cooling device characterized in that the piston cooling device is configured as a flat surface that is inclined by a certain amount.