JP4869121B2 - Piston for internal combustion engine - Google Patents

Description

  The present invention relates to a piston for an internal combustion engine, and in particular, forms an annular cooling cavity on the outside of a combustion chamber of a piston for a diesel engine, that is, on the outer peripheral wall of the top of the piston, and cools by injecting cooling oil from a lower injection nozzle. The present invention relates to a piston for an internal combustion engine having a cooling device that flows into a cavity and cools the piston with this cooling oil.

Conventionally, in a piston that requires high heat resistance in a high-power diesel engine, in order to suppress the temperature rise of the lip portion of the combustion chamber and the piston ring groove, the outer peripheral wall portion outside the combustion chamber of the piston is used. An example in which a cooling cavity is provided and oil is injected from a lower injection nozzle toward the cooling cavity is a well-known technique in which the piston cooling efficiency is improved, such as Japanese Utility Model Laid-Open No. 1-58712 and Japanese Patent Laid-Open No. 9-96248. Known in the Gazette.
Japanese Utility Model Publication No. 1-58712 JP-A-9-96248

  In such a conventional technique, as shown in FIGS. 6 and 7, the piston 100 that slides within the cylinder 101 of the diesel engine has an annular cooling cavity 102 at the top. The cooling cavity 102 is similarly formed in an annular cooling passage 103, an intake port 104 that communicates with the annular cooling passage 103 in a substantially T-shape and at a position spaced approximately 180 ° from the intake port 104. An annular cooling passage 103 and a discharge port 105 communicating in a substantially T shape are configured. As shown in FIG. 7, the cooling cavity 102 is used for smoothly diverting and guiding the cooling oil injected from the injection nozzle 110 and supplied to the intake port 104 into the annular cooling passage 103 in mutually opposite directions. A mountain-shaped oil distribution wall 106 having a pair of arcuate slopes S1, S2 is integrally formed.

  The center of the injection nozzle 110 that supplies the cooling oil to the cooling cavity 102 of the piston 100 and the center of the oil distribution wall 106 of the cooling cavity 102 of the piston 100 orthogonal to the T shape are the same and coincide with each other. The cooling oil injected from 110 to the intake port 104 collides with the arcuate slopes S1 and S2 or the chevron-shaped portion of the oil distribution wall 106, so that the cooling oil with an equal flow rate flows to the left and right through the annular cooling passage 103. It has become. For this reason, cooling in the cooling cavity 102 at the top of the piston 100 is performed uniformly.

  However, the intake 104 may not be orthogonal to the annular cooling cavity 102 or the injection nozzle 110 may be installed in a state where the injection nozzle 110 is inclined in the circumferential direction due to the engine layout.

  In such a case, in the conventional chevron-shaped portion, when the piston 100 moves up and down, as shown in FIGS. 8, 9, 10, and 11, when the piston 100 is at the top dead center and the bottom dead center, Since the cooling oil injected from 110 to the intake 104 does not hit the arcuate slope of the chevron 108 or the central part of the chevron-shaped distribution wall 109, the chevron 108 and the distribution wall 109 enter the cooling cavity 102. Since the top of the piston 100 is not evenly divided and the top temperature of the piston 100 is not evenly cooled, a crack occurs at the top of the piston 100, resulting in a decrease in engine durability.

  Therefore, it is necessary to efficiently cool the piston 100 by adjusting the flow of the cooling oil in the cooling cavity 102 in order to lower the temperature at the top of the piston 100.

  In view of the above-described problems, the present invention provides a piston even when an injection nozzle or an intake for injecting cooling oil from below into a cooling cavity formed in the piston is inclined with respect to the circumferential direction of the cooling cavity. It is an object of the present invention to provide a piston for an internal combustion engine having a cooling device that efficiently cools the temperature at the top of the piston by cooling oil being evenly divided into the cooling cavity at all times even if it moves up and down. .

In order to achieve the above object, a piston for an internal combustion engine according to the present invention is a piston for an internal combustion engine having a cooling device in which an annular cooling cavity is formed in an outer peripheral wall portion of a piston top portion of the engine for an internal combustion engine. Has an injection nozzle that is inclined in the circumferential direction in the axial direction of the piston, and cools by taking in the cooling oil injected in the direction inclined in the circumferential direction in the axial direction of the piston by the injection nozzle toward the cooling cavity. An oil intake is provided , and a piston circle is formed in a part of the cooling cavity so that the injected cooling oil is substantially perpendicular to the piston top side of the connection portion of the cooling cavity with the cooling oil intake. A distribution wall inclined in the circumferential direction is provided, and the cooling oil flows from the cooling oil intake through the cooling cavity.

  The piston for an internal combustion engine according to the present invention is characterized in that a plurality of cooling oil intakes and discharge ports are provided, and cooling oil is directed to each cooling oil intake and discharge port.

Furthermore, the piston for an internal combustion engine of the present invention is provided with a wall formed in a planar shape on the cooling cavity side of the cooling oil intake, and the cooling oil intake is provided perpendicularly to the distribution wall on the wall. It is characterized by that .

  According to the present invention, the piston for the internal combustion engine is used to distribute the cooling oil to the cooling cavity by injecting the cooling oil into the cooling cavity from the injection nozzle installed in a state where the piston is inclined in the circumferential direction. By providing a distribution wall that is substantially perpendicular to the injection angle, the cooling oil hits the distribution wall at a substantially right angle so that an equal flow of cooling oil is diverted to the cooling cavity from side to side. Therefore, the cooling in the cooling cavity at the top of the piston is uniformly performed. As a result, the temperature of the lip portion of the combustion chamber is controlled to prevent cracking of the piston top, and an excellent effect of improving the durability of the engine is obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
(Example)
FIG. 1 is a sectional view of a piston for an internal combustion engine according to the present invention, and FIG. 2 is a schematic diagram showing a cooling cavity and a cooling oil intake port of the piston in FIG. Is indicated by a solid line, the injection state of the cooling oil at the top dead center is indicated by a virtual line (dashed line), and FIGS. 3 to 5 are schematic diagrams showing modifications of the cooling oil intake in FIG. is there.

  As shown in FIG. 1, a piston 1 for an internal combustion engine according to the present invention is configured to slide in a cylinder of a diesel engine, for example, and an annular cooling cavity 2 is provided in an outer peripheral wall portion at the top of the piston 1. It has been. The cooling cavity 2 includes an annular cooling passage 3, a cooling oil intake 4 provided so as to obliquely intersect and communicate with the annular cooling passage 3, and the intake 4 And a discharge port 5 provided so as to intersect the annular cooling passage 3 at a substantially right angle at a position approximately 180 ° away from the annular cooling passage 2 and the intake port 4 for the cooling oil. And the discharge port 5 constitute a cooling device for the piston 1.

  As described above, the intake 4 is provided in a direction perpendicular to the outer peripheral wall portion of the piston 1, that is, obliquely inclined with respect to the central axis direction of the piston 1. 5 are preferably provided diametrically opposite one another along the top wall of the piston 1. In the illustrated embodiment, one cooling oil intake 4 and one discharge outlet 5 are provided for each, but a plurality of cooling oil intakes 4 and discharge outlets 5 can be provided as necessary.

  The cooling cavity 2 is formed in an annular shape along the top outer peripheral wall portion of the piston 1, and an inclined intake 4 provided opposite to the diametrical direction of the piston 1 and a substantially right discharge port 5 are formed in an annular shape. The cooling cavity 2 is provided in communication. Accordingly, the cooling oil injected from the injection nozzle 10 is injected toward the intake port 4 in the direction of the arrow, enters the intake port 4 and flows in the annular cooling cavity 4. Is uniformly and well cooled, and the durability of the piston 1 is improved.

  In addition, the cooling oil that has circulated in the cooling cavity 2 of the piston 1 and cooled the top of the piston 1 is discharged from the discharge port 5 on the opposite side and accumulated in the oil reservoir at the lower part of the cylinder. The liquid is again supplied to the injection nozzle 10 by the pump and is injected from the injection nozzle 10.

  As shown in FIG. 2, the cooling oil 2 injected from the injection nozzle 10 and supplied to the intake port 4 is smoothly divided and guided in the opposite directions into the annular cooling passage 3. For this purpose, a distribution wall 6 substantially orthogonal to the injection direction is integrally formed, and is provided in a planar shape in the drawing. Such a distribution wall 6 is not limited to a planar shape, and may be formed in a curved surface shape corresponding to a cross-sectional shape of the annular cooling cavity 2, for example, a cross-sectional shape such as an oval shape or an elliptical shape. In FIG. 2, the cooling oil injection state at the bottom dead center of the piston 1 is indicated by a solid line, and the cooling oil injection state at the top dead center is indicated by a virtual line (one-dot chain line).

  As shown in the figure, the distribution wall 6 includes an annular cooling cavity 2 provided at the top of the piston 1 and a cooling provided so as to be inclined with respect to the vertical direction of the piston 1 along the outer peripheral wall of the piston 1. At the intersection with the oil intake 4, it is provided so as to form a plane portion substantially perpendicular to the cooling oil injection direction. In addition, the inlet portion of the intake port 4 is preferably formed in a divergent shape as shown in the figure by, for example, dishing so that the cooling oil can be satisfactorily received.

  Therefore, the cooling oil injected at a bottom dead center position of the piston 1 from the injection nozzle 10 with a required inclination angle, as indicated by a solid line in FIG. Is fed into the cooling cavity 2 of the piston 1 through the part and hits the distribution wall 6 of the upper ceiling part of the cooling cavity 2 at the intersection of the cooling cavity 2 and the inlet 4 in the left-right direction. Divided into equal parts. That is, the cooling oil injected into the intake port 4 hits the distribution wall 6 in a state of being substantially perpendicular to the injection direction. The cooling cavity 2 is divided into left and right along the cooling passage 3 and flows.

  Further, the cooling oil injected at the position of the top dead center of the piston 1 slightly shifts downward in the position of the injection nozzle 10 at the position of the bottom dead center, as shown by a virtual line (one-dot chain line) in FIG. Is injected into the cooling cavity 2 of the piston 1 through a portion of the inlet 4 at a position close to the right side of the inlet 4 after being injected from the injection nozzle 10 at the position (indicated by the phantom line). On the other hand, it strikes at a substantially right angle and is divided into equal parts in the left and right directions to flow in the cooling cavity 2.

  In this manner, the cooling oil injected from the injection nozzle 10 is distributed on the distribution wall 6 in the cooling cavity 2 of the piston 1 that intersects the injection direction at any of the bottom dead center and the top dead center of the piston 1. The cooling oil flows in the cooling passage 3 of the annular cooling cavity 2 as a cooling oil having a substantially equal flow rate on the left and right sides at a substantially right angle with respect to the flat surface portion or the curved surface portion, whereby the top portion of the piston 1 is cooled. Cooling oil flowing in the cavity 2 is uniformly cooled. The oil that has flowed through the cooling cavity 2 to cool the piston 1 is preferably discharged from the discharge port 5 on the side opposite to the intake port 4 and stored in an oil reservoir at the bottom of the cylinder. The oil stored in the oil reservoir is supplied again to the injection nozzle 10 by an appropriate oil pump and is injected from the injection nozzle 10. It should be noted that the distribution wall 6 not only in the case of a planar shape, but also in the case of a curved surface shape such as an oval shape or an elliptical shape corresponding to the cross-sectional shape of the cooling cavity 2, the cooling oil is satisfactorily left and right. It can act to divide and flow evenly.

  Therefore, in the piston 1 of the present invention, the cooling oil injected from the injection nozzle 10 hits the distribution wall 6 through the intake port 4 at a substantially right angle at both the bottom dead center and the top dead center. Therefore, the cooling oil is equally divided into left and right so that it can flow in the cooling cavity 2, and the top of the piston 1 can be cooled well.

  Conventionally, when the piston moves up and down and the piston reaches the bottom dead center and the top dead center, the cooling oil injected from the injection nozzle to the intake port is caused by the arcuate slope of the chevron-shaped portion or the chevron-shaped distribution wall. In order not to hit the center well, the conventional chevron-shaped part and distribution wall do not evenly distribute the cooling oil into the cooling cavity, but the piston top temperature rises and cracks occur in the piston top. As a result, there was a problem that the durability of the engine was lowered. However, in the piston 1 of the present invention, the top of the piston 1 located at the bottom dead center and the top dead center is cooled well by the cooling oil. Therefore, the piston 1 can be efficiently cooled by suitably adjusting the flow of the cooling oil in the cooling cavity 2 in order to lower the temperature at the top of the piston 1.

  In the piston 1 of the present invention, as shown in FIG. 2, the annular cooling cavity 2 provided at the top of the piston 1 and the cooling oil injected from the injection nozzle 10 intersect with each other in the injection direction. Since the distribution wall 6 is provided so as to be substantially orthogonal to each other, the cooling oil hits the distribution wall 6 at a substantially right angle regardless of whether the piston is located at the bottom dead center or the top dead center. The cooling oil hitting the distribution wall 6 is well divided into two at the distribution wall 6 and flows into the cooling cavity 2, so that the top of the piston 1 is cooled evenly.

  Several variants of the cooling oil inlet 4 for the distribution wall 6 of the cooling cavity 2 formed as described above are shown in FIGS. 3 to 5, the cooling oil injection state at the bottom dead center of the piston is indicated by a solid line, and the cooling oil injection state at the top dead center of the piston is indicated by a virtual line (dashed line). Yes.

  In the intake port 4 of the piston 1 shown in FIG. 3, the distribution wall 6 is provided in the cooling cavity 2 so as to be formed substantially at right angles to the cooling oil injection direction, and the intake port 4 facing this is provided. The outlet portion 4A is formed as a straight passage, and the inlet portion 4a is formed as a portion that is enlarged in a dish shape, so that the cooling oil injected from the injection nozzle 10 can be received well. It is like that.

  Accordingly, the cooling oil sprayed from the spray nozzle 10 is preferably received at the inlet portion 4a, passes through the straight outlet portion 4A of the intake port 4 and strikes the distribution wall 6 at a substantially right angle and is evenly divided to the left and right. Therefore, the divided cooling oil flows evenly in the cooling cavity 2 and cools the top of the piston 1 satisfactorily. Thereby, since the piston 1 is suitably cooled, the top portion of the piston 1 is favorably cooled by the cooling oil, so that the occurrence of cracks can be suitably suppressed, and the piston 1 can be efficiently cooled.

  Further, as shown by a solid line in FIG. 3, the cooling oil injected from the injection nozzle 10 (the position of the solid line) at the bottom dead center position of the piston is distributed through a portion closer to the left side of the intake port 4. It strikes the wall 6 at a substantially right angle and is divided into the left and right substantially equally and flows in the cooling cavity 2. Further, the cooling oil injected from the injection nozzle 10 (the position of the phantom line) at the top dead center position of the piston hits the distribution wall 6 at a substantially right angle through a portion close to the right side of the intake port 4. As a result, the piston is diverted substantially evenly to the left and right and flows in the cooling cavity 2 to cool the piston well.

  In the intake port 4 of the piston 1 shown in FIG. 4, the distribution wall 6 is formed so as to be substantially perpendicular to the injection direction of the cooling oil, and the outlet portion 4B of the intake port 4 is formed in the cooling cavity 2. The inlet passage 4b is formed in a dish shape so that it can receive the cooling oil suitably. Moreover, since the exit part 4B is provided in the shape of a long hole, cooling oil can be taken in in a wide range.

  Accordingly, the cooling oil injected from the injection nozzle 10 is suitably received at the inlet portion 4b, and is equally divided into the left and right through the intake port 4 at a substantially right angle to the distribution wall 6, and the divided cooling oil is cooled. The top of the piston 1 is cooled well by flowing uniformly in the cavity 2. Thereby, since the piston 1 is suitably cooled, the temperature rise at the top of the piston 1 can be suppressed, the occurrence of cracks can be prevented well, and the piston 1 can be efficiently cooled.

  Further, as shown by the solid line in FIG. 4, the cooling oil injected from the injection nozzle 10 (the position of the solid line) at the bottom dead center position of the piston is removed in the same manner as described above with reference to FIGS. After passing through the portion of the inlet 4 that is closer to the left side, it strikes the distribution wall 6 at a substantially right angle and is divided into the left and right substantially equally and flows in the cooling cavity 2. Further, the cooling oil injected from the injection nozzle 10 (the position of the phantom line) at the top dead center position of the piston hits the distribution wall 6 at a substantially right angle through a portion close to the right side of the intake port 4. As a result, the piston is diverted substantially evenly to the left and right and flows in the cooling cavity 2 to cool the piston well.

  In the intake port 4 of the piston 1 shown in FIG. 5, the distribution wall 6 is formed so as to be substantially perpendicular to the cooling oil injection direction, and the shape of the outlet hole of the outlet portion 4 </ b> C of the intake port 4. Is provided so as to be substantially parallel to the distribution wall 6. In this way, when the shape of the outlet hole of the outlet portion 4C of the intake port 4 is substantially parallel to the distribution wall 6, the cooling oil injected from the injection nozzle 10 comes out of the outlet hole of the outlet portion 4C. The distribution wall 6 is divided into the right and left evenly at a substantially right angle, and a uniform flow can be maintained by the parallel portion of the outlet hole of the outlet part 4C. 1 is suitably cooled.

  Accordingly, the cooling oil sprayed from the spray nozzle 10 is preferably received at the inlet portion 4c, passes through the straight outlet portion 4C of the intake port 4 and strikes the distribution wall 6 at a substantially right angle and is evenly divided to the left and right. Therefore, the divided cooling oil flows evenly in the cooling cavity 2 and cools the top of the piston 1 satisfactorily. Thus, since the piston 1 is suitably cooled, the top of the piston 1 is well cooled by the cooling oil, so that the occurrence of cracks can be suitably prevented, and the piston 1 can be efficiently cooled. it can.

  Further, as indicated by the solid line in FIG. 5, the cooling oil injected from the injection nozzle 10 (the position indicated by the solid line) at the position of the bottom dead center of the piston approaches the left side of the intake 4 as described above. Through this portion, it strikes the distribution wall 6 at a substantially right angle and is divided into the left and right substantially equally and flows in the cooling cavity 2. Further, the cooling oil injected from the injection nozzle 10 (the position of the phantom line) at the top dead center position of the piston hits the distribution wall 6 at a substantially right angle through a portion close to the right side of the intake port 4. As a result, the piston is diverted substantially evenly to the left and right and flows in the cooling cavity 2 to cool the piston well.

  As described above, when the piston 1 moves up and down and is positioned at either the bottom dead center or the top dead center, the piston 1 is connected to the outlet portion of the intake port 4 as shown in FIGS. 4A, 4B, and 4C can be formed in various shapes corresponding to the distribution wall 6 of the cooling cavity 2, and in any case, the cooling oil is preferably diverted to flow into the cooling passage 3 to flow into the cooling cavity 2. As a result, the piston 1 can be effectively cooled.

  Accordingly, the cooling oil sprayed from the spray nozzle 10 is suitably received at the inlet 4 and the inlet portions 4a, 4b, and 4c, and the linear outlet portions 4A, 4B, and 4C of the inlet 4 and the inlet 4 are provided. The cooling oil thus divided flows into the right and left sides substantially evenly at right angles to the distribution wall 6, so that the divided cooling oil flows evenly in the cooling cavity 2 along the cooling passage 3 and passes through the top of the piston 1. Cools well. Thereby, since the piston 1 is suitably cooled, the top portion of the piston 1 is favorably cooled by the cooling oil, so that the occurrence of cracks can be suitably suppressed, and the piston 1 can be efficiently cooled.

  In addition to the diesel engine, it can be used as a cooling device capable of suitably cooling a piston such as a gasoline engine or a compressor.

Sectional drawing of the piston for internal combustion engines in this invention, FIG. 2 is a partial sectional view showing an annular cooling cavity and a cooling oil intake port of the piston for the internal combustion engine of FIG. 1; FIG. 3 is a partial sectional view showing a modification of the annular cooling cavity and the cooling oil intake of the piston for the internal combustion engine of FIG. 2; FIG. 3 is a partial sectional view showing another modification of the annular cooling cavity and the cooling oil intake of the piston for the internal combustion engine of FIG. 2; FIG. 7 is a partial sectional view showing still another modification of the annular cooling cavity and the cooling oil intake port of the piston for the internal combustion engine of FIG. Sectional drawing of the piston for conventional internal combustion engines, FIG. 6 is a partial sectional view showing an annular cooling cavity and a cooling oil intake of the piston for the internal combustion engine of FIG. FIG. 6 is a sectional partial view showing the annular cooling cavity and the cooling oil intake of the piston for the internal combustion engine of FIG. 6 by changing the angle by 90 degrees along the outer periphery of the piston. FIG. 8 is a partial sectional view showing a modification of the annular cooling cavity and the cooling oil intake of the piston for the internal combustion engine of FIG. FIG. 8 is a partial sectional view showing another modification of the annular cooling cavity and the cooling oil intake of the piston for the internal combustion engine of FIG. FIG. 10 is a partial cross-sectional view showing still another modification of the annular cooling cavity and the cooling oil intake port of the internal combustion engine piston of FIG. 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 2 Cooling cavity 3 Cooling passage 4 Intake 5 Discharge 6 Distribution wall 10 Injection nozzle

Claims (3)

In the internal combustion engine piston having a cooling device in which an annular cooling cavity is formed in the outer peripheral wall portion of the piston top of the internal combustion engine,
The cooling device includes an injection nozzle that is inclined in the circumferential direction in the axial direction of the piston, and the cooling oil that is injected in the direction inclined in the circumferential direction in the axial direction of the piston by the injection nozzle toward the cooling cavity. has a inlet for introducing cooling oil, the piston top side of the connecting portion between inlet for cooling oil of the cooling cavity, a portion of the cooling cavity so injected cooling oil strikes approximately at right angles A piston for an internal combustion engine, comprising a distribution wall inclined in a circumferential direction of the piston , wherein the cooling oil flows in the cooling cavity from the cooling oil intake.   2. The piston for an internal combustion engine according to claim 1, wherein a plurality of the cooling oil intakes and discharge ports are provided, and the cooling oil is directed to each of the cooling oil intakes and discharge ports. The wall formed in a planar shape is provided on the cooling cavity side of the cooling oil intake, and the cooling oil intake is provided perpendicular to the distribution wall on the wall. Piston for internal combustion engine.

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