JP2007315244A - Piston cooling device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance piston cooling effect by improving the flow of an oil in an oil passage. <P>SOLUTION: The oil jetted from an oil jet 16 is automatically selected between a reflected inflow to the lower wall surface 12a side of the oil passage 12 and a reflected inflow to the upper wall surface 12b side with respect to near the intermediate portion of the piston 3 by the tilted guide wall 15 of the oil passage 12 and the inclination of the oil jetting direction of the oil jet 16. A remaining oil T on the lower wall surface 12a and the upper wall surface 12b is surely pushed back into the oil passage 12 in the oil moving direction. Consequently, the stagnation of oil in the oil passage 12 and the closed state of the oil passage 12 due to the stagnation can be eliminated, and the oil can be smoothly circulated. As a result, the cooling effect on the piston 3 can be largely enhanced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to cooling of a piston constituting an internal combustion engine.

  In order to prevent the temperature of the piston from rising, a technique is known in which an oil passage is formed inside the piston, and oil is circulated in the oil passage to cool the piston from the inside.

For example, the piston cooling device disclosed in Patent Document 1 forms a spiral protrusion 10 a on the wall surface of an oil passage 10 provided inside the piston 3. When the oil jetted from the oil jet 13 installed in the crank chamber 14 below the piston 3 is introduced into the oil passage 10 via the introduction passage 11, the oil is divided into left and right, and the projections 10a adjacent to the projection 10a are respectively separated. After flowing along the spiral groove formed between them, it is discharged from the outlet passage 12. Therefore, since oil flows spirally in the oil passage 10, the upper and lower sides of the piston can be efficiently cooled.
JP 2004-232589 A

  However, since the piston 3 reciprocates between the top dead center and the bottom dead center at a high speed, a large inertia force is applied to the oil in the oil passage 10. That is, when the piston 3 moves toward the top dead center, the oil receives a downward inertia force and stays on the lower wall side in the oil passage 10, and conversely, the piston 3 moves toward the bottom dead center. At this time, the oil receives an upward inertia force and stays on the upper wall side in the oil passage 10.

  As a result, a large amount of oil stays on the wall surface of the oil passage 10 near the introduction passage 11 and the oil passage 10 is closed. Further, when the oil passage 10 is blocked by the accumulated oil, the oil injected from the oil jet 13 is difficult to be introduced into the oil passage 10. As a result, the oil in the oil passage 10 becomes difficult to flow, and there is a problem that a large cooling effect of the piston 3 cannot be expected.

  An object of the present invention is to improve the flow of oil in the oil passage and enhance the cooling effect of the piston.

  According to a first aspect of the present invention, there is provided an internal combustion engine including an oil passage, a piston having an oil passage, an oil introduction passage, and a discharge passage, and an oil jet. The oil jet is connected to a connection portion between the oil passage and the introduction passage. A guide wall for switching the course of the injected oil is provided, and the oil injection direction of the oil jet is inclined toward the oil traveling direction of the oil passage.

  According to the first aspect of the present invention, the propulsive force of the oil injected from the oil jet can be efficiently applied to the oil staying in the oil passage and the flow of the oil can be improved. The effect is enhanced.

  The present invention according to claim 2 is characterized in that the guide wall is formed in a flat plate shape and inclined toward the oil traveling direction side, so that the configuration of the guide wall can be simplified, and the inclination angle of the guide wall With this setting, the oil reflection angle can be adjusted appropriately.

  According to a third aspect of the present invention, the position where the course of the oil jetted from the oil jet is switched between the inner side and the outer side of the guide wall is set at a substantially middle point of the sliding region of the piston. Therefore, the thrust is applied almost evenly to the oil staying on the lower wall side of the oil passage when the piston is moving to the top dead center side and the oil staying on the upper wall side of the oil passage moving to the bottom dead center side. The flow of oil in the oil passage can be improved most effectively.

  According to a fourth aspect of the present invention, the oil passage is formed in a C-shape that makes one round around the piston, the introduction passage is connected to one end of the oil passage, and the discharge passage is connected to the other end. Since it is connected and the oil is circulated in one direction, the function and effect of the first aspect can be obtained with an extremely simple configuration including one oil passage, one guide wall, and one oil jet. Can do.

  According to the present invention, the oil flow in the oil passage can be improved by utilizing the propulsive force of the oil injected from the oil jet, so that the piston cooling effect can be enhanced.

(First embodiment)
Hereinafter, the first embodiment will be described with reference to FIGS.
FIG. 1 is a partial cross-sectional view showing an outline of a diesel engine as an internal combustion engine embodying the present invention. In addition, except the structure relevant to this invention, it is the same as the structure of a well-known diesel engine.

  A cylindrical cylinder liner 2 is mounted inside the cylinder block 1. A piston 3 is fitted inside the cylinder liner 2 so as to be slidable in the vertical direction of FIG. An upper space of the piston 3 is formed as a combustion chamber 4, and a crank chamber 5 is formed below the piston 3.

  The piston 3 is rotatably connected to one end (the upper end in FIG. 1) of a connecting rod 7 by a piston pin 6, and the other end of the connecting rod 7 is a crank pin of a crank shaft (not shown) disposed in the crank chamber 5. 8 is rotatably connected. A piston ring 10 is mounted in an annular ring groove 9 formed on the outer peripheral surface of the piston 3. The cylinder block 1 is provided with a water jacket 11 for cooling.

  As is apparent from FIG. 2A, a C-shaped oil passage 12 that substantially goes around the periphery of the piston 3 is formed substantially parallel to the upper surface of the piston 3 inside the piston 3. The oil passage 12 is formed in a circular cross section, one end of which is connected to an oil introduction passage 13 that opens to the lower surface of the piston 3, and the other end that is connected to an oil discharge passage 14 that also opens to the lower surface of the piston 3. is doing. In addition, although the diameter of the oil passage 12, the introduction passage 13, and the discharge passage 14 in this embodiment is formed in about 5 mm, these diameters are variously changed according to the diameter of the piston 3. FIG.

  The oil passage 12 includes a guide wall 15 formed in a flat plate shape at a connecting portion with the introduction passage 13 (see FIGS. 1 and 2B). The guide wall 15 is disposed at an angle of approximately 45 degrees to the oil traveling direction side of the oil passage 12 with respect to the central axis (not shown) of the introduction passage 13, and as shown in FIG. Connected to the wall. A predetermined gap is formed between the guide wall 15 and the upper wall surface 12 b and the lower wall surface 12 a of the oil passage 12.

  The guide wall 15 is formed in the oil passage 12 by the following method. That is, generally, the oil passage 12, the introduction passage 13, and the discharge passage 14 are formed using a core. Accordingly, the guide wall 15 can be formed by engraving a 45 degree slit in the direction crossing the oil passage 12 in the core forming the connecting portion between the oil passage 12 and the introduction passage 13. is there. In addition, although the thickness of the slit, that is, the guide wall 15 is formed to be about 1.5 mm, it is not limited to this thickness.

  On the other hand, an oil jet 16 is disposed in a part of the crank chamber 5. The oil jet 16 has an injection port directed toward the introduction passage 13, and is further inclined at a predetermined angle θ toward the oil traveling direction side of the oil passage 12 with respect to the central axis (not shown) of the introduction passage 13. Has been. Note that the inclination angle θ of the oil jet 16 is set in the range of approximately 1 to 2 degrees in the present embodiment, but is not limited to this angle. Further, although not shown, the oil jet 16 is connected to an oil pump via a pressure regulating valve and a pipe line, and is the same as the prior art in that the oil jet 16 is always injected during high-speed rotation of the diesel engine.

The operation of the first embodiment configured as described above will be described with reference to FIG. FIG. 3 shows the piston 3 at the top dead center, the middle point, and the bottom dead center by a solid line for convenience.
When the diesel engine starts operation, the piston 3 slides back and forth between the top dead center and the bottom dead center. Further, oil is constantly injected from the oil jet 16 toward the introduction passage 13.

  The oil flowing into the oil passage 12 from the introduction passage 13 is likely to stay on the lower wall surface 12a of the oil passage 12 when the piston 3 moves to the top dead center side due to the influence of the inertial force due to the reciprocating sliding of the piston 3. Become. This staying oil is indicated by T in FIG.

  However, in this embodiment, the oil injected into the introduction passage 13 takes a course inside the inclined guide wall 15 and collides with the inner surface 15a. Therefore, the oil is reflected toward the staying oil T on the lower wall surface 12a side and flows into the oil passage 12 as indicated by an arrow at the piston 3 at the top dead center position in FIG. Therefore, the staying oil T is caused to flow to the inner side of the oil passage 12 by the propulsion force of the reflected oil, and the staying of oil is eliminated.

  When the piston 3 reverses from the top dead center and moves toward the bottom dead center, the oil tends to stay on the upper wall surface 12b of the oil passage 12 due to the influence of the inertial force. However, since the oil jet 16 is inclined, the path of the oil injected into the introduction passage 13 is the lower end 15b of the guide wall 15 as indicated by the arrow at the piston 3 at the midpoint position in FIG. And flows outside the guide wall 15 into the oil passage 12 without colliding with the guide wall 15.

  For this reason, while the piston reaches the bottom dead center from the middle point, the oil directly collides with the upper wall surface 12b of the oil passage 12 as indicated by the arrow at the piston 3 at the bottom dead center position. In addition, since the injection direction of the oil jet 16 is inclined, the oil is reflected at a predetermined angle and travels toward the accumulated oil T on the upper wall surface 12 b side of the oil passage 12. Therefore, the staying oil T is caused to flow to the back side of the oil passage 12 by the propulsion force of the reflected oil, and the staying of the oil is eliminated even when the piston 3 moves to the bottom dead center side.

  In the first embodiment, due to the inclination of the inclined guide wall 15 and the oil jet 16 in the oil injection direction, the course of the oil injected from the oil jet 16 is the lower wall surface of the oil passage 12 around the middle point of the piston 3. It is automatically switched between the reflection inflow to the 12a side and the reflection inflow to the upper wall surface 12b side. For this reason, the staying oil T on the lower wall surface 12 a and the upper wall surface 12 b is reliably pushed away in the oil traveling direction of the oil passage 12. Accordingly, the oil stays in the oil passage 12 and the closed state of the oil passage 12 due to the stay is eliminated, and the oil is smoothly circulated, so that the cooling effect of the piston 3 can be greatly enhanced.

The above-described first embodiment of the present invention has the following effects.
(1) Since the guide wall 15 has a flat plate shape, the configuration is simple, and the inclination angle can be freely set. Therefore, the reflection direction of the oil jetted from the oil jet 16 can be easily set. In addition, the guide wall can be easily formed because it is only necessary to make a slit in the core.
(2) The oil passage 12 is formed as a single passage around the circumference of the piston 3 and circulates oil in one direction. Therefore, the passage can be easily formed, and the guide wall 15 and the oil jet 16 are provided. Can be installed in one place, so the structure of the cooling device is simple.
(3) Since the switching position of the course of the oil jetted from the oil jet 16 is set approximately in the middle of the sliding area of the piston 3, oil flows into the upper wall surface 12b of the oil passage 12 and oil flows into the lower wall surface 12a. The inflow can be performed uniformly, and oil retention can be reliably eliminated.

  The second to fourth embodiments of the present invention shown below are modified guide wall configurations in the first embodiment, and the same configurations as those in the first embodiment are denoted by the same reference numerals. Detailed description is omitted.

(Second Embodiment)
The guide wall 17 in the second embodiment shown in FIG. 4 is configured in a bowl shape by a flat plate portion 17a located in the introduction passage 13 and a flat plate portion 17b bent from the flat plate portion 17a to the oil passage 12 side at a substantially right angle. ing. When the piston 3 is located on the top dead center side, the oil injected into the introduction passage 13 passes through the inside of the guide wall 17 and collides with the inner surface 17C of the flat plate portion 17b as indicated by the solid line arrow. The light is reflected to the lower wall surface 12 a side of the oil passage 12 and flows into the oil passage 12. Further, when the piston 3 is located on the bottom dead center side, the oil injected into the introduction passage 13 passes through the outside of the guide wall 17 and reaches the upper wall surface 12b of the oil passage 12 as shown by the dotted arrow. Reflect and collide. However, since the oil injection direction is slightly inclined, the oil that has collided with the upper wall surface 12 b is reflected in a direction along the upper wall surface 12 b and flows into the oil passage 12.

  In the second embodiment, the saddle-shaped guide wall 17 is disposed at the connecting portion between the introduction passage 13 and the oil passage 12, so that the oil injected at the positions of the top dead center side and the bottom dead center side of the piston 3 is reduced. The course can be switched between the inside and the outside of the guide wall 17. Accordingly, the oil injected in the same manner as in the first embodiment described above can positively push away both the oil staying on the lower wall surface 12a side of the oil passage 12 and the oil staying on the upper wall surface 12b side.

(Third embodiment)
The guide wall 18 in the third embodiment shown in FIG. 5 has a configuration in which the entire inner surface 18a and outer surface 18b are formed as curved surfaces. Similar to the first embodiment, the oil jetted from the oil jet 16 is guided to the inner surface 18a on the top dead center side of the piston 3 as indicated by the solid line arrow, and the lower wall surface 12a of the oil passage 12 It flows in to the side. Further, on the bottom dead center side of the piston 3, as indicated by the dotted arrow, it is guided by the outer surface 18 b and flows into the upper wall surface 12 b side of the oil passage 12. The third embodiment has the same operational effects as the first embodiment.

(Fourth embodiment)
An inner surface 19a and an outer surface 19b of the guide wall 19 in the fourth embodiment shown in FIG. 6 are formed as curved surfaces. Further, the tip 20 of the guide wall 19 on the oil passage 12 side is formed with a curved surface having a small curvature radius so that the tip inner surface 20a following the inner surface 19a is directed to the lower wall 12a of the oil passage 12, and the tip following the guide wall 19b. The outer surface 20b is formed with a curved surface having a large curvature radius so that the outer surface 20b faces the upper wall surface 12b of the oil passage 12.

  In the fourth embodiment, the flow of oil when the piston 3 is on the top dead center side is guided by the tip inner surface 20a and directed directly to the lower wall surface 12a of the oil passage 12, as indicated by the solid line arrow, The propulsive force with respect to the staying oil on the lower wall surface 12a side can be increased. When the piston 3 is on the bottom dead center side, as indicated by the dotted arrow, the oil is guided to the outer surface 20b of the tip and directed directly to the upper wall surface 12b of the oil passage 12, and against the accumulated oil on the upper wall surface 12b side. The driving force can be increased.

  The present invention is not limited to the configuration of each of the embodiments described above, and various modifications are possible within the scope of the gist of the present invention, and can be implemented as follows.

(1) The guide walls 15, 17, 18, and 19 are not limited to the configuration in which the guide walls 15, 17, 18, and 19 are formed so as to cross the entire region of the oil passage 12. You may form so that the area | region of about 3 may be crossed.
(2) The guide walls 15, 17, 18, and 19 are not limited to the configuration in which the guide walls 15, 17, 18, and 19 are integrally formed with the piston 3.
(3) The switching position of the course of the oil jetted from the oil jet 16 by the guide walls 15, 17, 18, 19 is not limited to the substantially middle point of the sliding area of the piston 3, but the top dead center side or the bottom dead center You may set to the position biased to the side. This switching position can be set by appropriately changing the inclination angle of the guide walls 15, 17, 18, 19 and the inclination angle θ of the oil jet 16.
(4) In the first embodiment, the guide wall 15 may be disposed substantially parallel to the oil passage 12 without being inclined.
(5) In the second embodiment, the guide wall 17 may be formed so that the inner side and the outer side of the connecting portion between the flat plate portions 17a and 17b are curved.

(6) The oil passage 12 is not limited to the configuration in which one passage is formed as in each of the above-described embodiments. For example, two semicircular oil passages are arranged in line symmetry, or three arc-shaped oil passages are provided. For example, a plurality of oil passages may be provided such as a passage. In this case, the introduction passages, the discharge passages, and the oil jets may be provided by the number of oil passages.
(7) The cross-sectional shape of the oil passage 12 is not limited to a circular shape, and may be configured in an arbitrary shape such as a square or a triangle.
(8) The introduction passage 13 and the discharge passage 14 may be formed by drilling.
(9) Although the example of the diesel engine is shown as the internal combustion engine in each of the above embodiments, the present invention can be implemented in other types of internal combustion engines such as a gasoline engine.

It is the schematic which carried out the partial cross section which shows the outline | summary of a diesel engine. (A) It is the sectional view on the AA line of FIG. (B) It is the BB sectional view taken on the line of FIG. It is explanatory drawing which shows the effect | action of 1st Embodiment. It is a partial sectional view showing a 2nd embodiment. It is a partial cross section figure showing a 3rd embodiment. It is a partial cross section figure showing a 4th embodiment.

Explanation of symbols

1 Cylinder block 3 Piston 4 Combustion chamber 5 Crank chamber 12 Oil passage 12a Lower wall surface 12b Upper wall surface 13 Introduction passage 14 Discharge passages 15, 17, 18, 19 Guide wall 16 Oil jet

Claims (4)

In an internal combustion engine comprising an oil passage formed inside, a piston having an oil introduction passage and a discharge passage communicating between the oil passage and the crank chamber, and an oil jet for injecting oil toward the introduction passage,
A guide wall for switching the course of the oil jetted from the oil jet is disposed at the connecting portion between the oil passage and the introduction passage, and the oil jet direction of the oil jet is inclined toward the oil traveling direction side of the oil passage. An internal combustion engine piston cooling device. The piston cooling device for an internal combustion engine according to claim 1, wherein the guide wall is formed in a flat plate shape and is inclined toward the oil traveling direction side. 2. The piston of the internal combustion engine according to claim 1, wherein a position at which a path of oil sprayed from the oil jet is switched between an inner side and an outer side of the guide wall is set at a substantially middle point of a sliding region of the piston. Refrigeration equipment. The oil passage is formed in a C-shape that goes around the piston substantially once, the introduction passage is connected to one end of the oil passage, the discharge passage is connected to the other end, and the oil is circulated in one direction. The piston cooling device apparatus for an internal combustion engine according to claim 1, wherein:

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