JP2019052628A - piston - Google Patents

Abstract

A piston with excellent productivity, which has a cooling channel with excellent cooling efficiency, can prevent the formation of a cast hole, and can omit welding and drilling. A piston includes a crown portion and a cooling channel. The crown portion 11 has a crown surface 11A that partitions the combustion chamber 9 of the internal combustion engine 1 and a back surface 11B. The cooling channel 15 is partitioned in a hollow metal tube 20 cast into the crown portion 11. The hollow metal tube 20 includes an integrally formed C ring portion 23, a first end portion 21, and a second end portion 22. The C ring portion 23 is disposed between the crown surface 11A and the back surface 11B. The first and second end portions 21 and 22 are curved from the C ring portion 23 toward the back surface 11B. [Selection] Figure 2

Description

  The present invention relates to a piston provided with a cooling channel.

  The internal combustion engine transmits the reciprocating motion of the piston to the crankshaft and outputs it as a rotational driving force. Since the combustion chamber becomes hot, the piston is heated. When the piston is heated excessively, piston wear and internal combustion engine knocking are likely to occur. For this reason, it is known to provide a cooling channel in the piston and to cool the piston by circulating lubricating oil from an oil jet in the piston.

  The cooling channel can be formed, for example, by casting a core hardened with salt or sand into a piston and then disassembling and removing the core. However, cracks may occur in the core during the manufacturing process. If molten aluminum enters the cracks in the core, the piston becomes defective and the yield decreases. In addition, it takes time to drill holes in the piston to form the inlet and outlet of the lubricating oil and to remove the core from these holes.

  Therefore, as shown in FIG. 7 of Patent Document 1, FIG. 3 of Patent Document 2, FIG. 19 of Patent Document 3, and the like, a metal plate having a U-shaped cross section is welded to the wear-resistant ring, Pistons with a cooling channel between them have been proposed. A wear-resistant ring with excellent wear resistance is cast on the outer peripheral surface of the piston. A wear ring with a cooling channel is cast, and when the piston cools and hardens, a hole is drilled in the cooling channel to form an inlet and an outlet for the lubricating oil.

  However, in the pistons described in Patent Documents 1 to 3, since the sheet metal must be welded over the entire circumference of the upper edge and the lower edge of the wear-resistant ring, the processing cost increases. Since the gas trapped in the cooling channel is heated and expanded when casting the piston, if there is a poor weld between the wear-resistant ring and the sheet metal, the gas leaks from the defective part and casts into the piston. May occur.

JP 2010-144580 A JP 2010-96022 A JP 2009-215978 A

  When the core is cast into the piston, there is a decrease in yield due to the crack in the core. Moreover, it takes time to remove the core. When a wear-resistant ring with a cooling channel is cast into the piston, the cost for welding the cooling channel increases. There are also defects such as cast holes due to poor welding. When a hole is formed with a drill to form an inlet and an outlet for the lubricating oil, man-hours are required for drilling. In addition, since a straight through-hole is formed, the curvature greatly changes at the boundary between the through-hole and the cooling channel and the flow path resistance increases. If the flow path resistance is large, part of the lubricating oil will bounce off without being introduced into the cooling channel.

  The object of the present invention is to provide a cooling channel with low flow resistance and excellent cooling efficiency, which can prevent the formation of cast holes due to gas confined in the cooling channel, and further eliminates welding and drilling. An object of the present invention is to provide a piston that is excellent in productivity.

  In one embodiment, the piston includes a crown portion and a cooling channel. The crown portion has a crown surface that defines a combustion chamber of the internal combustion engine, and a back surface opposite to the crown surface. The cooling channel is defined in a hollow metal tube cast into the crown portion. Lubricating oil injected toward the back surface circulates through the cooling channel. The hollow metal tube has a C ring portion, a first end portion, and a second end portion. The C ring portion, the first end portion and the second end portion are integrally formed. The C ring portion is disposed between the crown surface and the back surface. The first end portion is continuous with one end of the C ring portion. The second end portion is continuous with the other end of the C ring portion. The first end and the second end are curved from the C-ring toward the back.

  According to the piston of the present invention, the cooling channel is formed by an integrally formed hollow metal tube, so that removal of the core and welding of the wear-resistant ring can be omitted. Drilling is no longer essential. The gas in the cooling channel can escape from the first and second end portions to the outside of the piston, thereby preventing the formation of a cast hole. Therefore, it is possible to improve the productivity of the piston by reducing the number of steps while suppressing the occurrence of defects. Further, the first and second end portions are curved and the flow path resistance is small. The cooling efficiency of the cooling channel can be improved.

FIG. 1 is a cross-sectional view showing a schematic configuration of an internal combustion engine. FIG. 2 is a perspective view illustrating an example of the piston according to the first embodiment. FIG. 3 is a bottom view of the piston shown in FIG. 4 is a cross-sectional view taken along line F4-F4 in FIG. FIG. 5 is a cross-sectional view showing a modification of the first embodiment. FIG. 6 is a bottom view showing an example of the piston of the second embodiment. FIG. 7 is a bottom view showing an example of the piston of the third embodiment. FIG. 8 is a side view seen from the direction of arrow F8 in FIG. FIG. 9 is a side view seen from the direction of arrow F9 in FIG.

  The piston 10 of the present invention will be described with reference to FIGS. As will be described mainly with reference to FIG. 2, the piston 10 includes a hollow metal tube 20 cast into the crown portion 11. The inside of the hollow metal tube 20 is partitioned as a cooling channel 15. The hollow metal tube 20 has a first end portion 21, a second end portion 22, and a C ring portion 23.

  The first end portion 21, the second end portion 22, and the C ring portion 23 are integrally formed and are smoothly continuous. The C ring portion 23 is disposed between the crown surface 11A and the back surface 11B of the crown portion 11. The first and second end portions 21 and 22 are curved from the C ring portion 23 toward the back surface 11B, respectively, and the tips 21E and 22E are exposed from the back surface 11B to the outside of the piston 10. In addition, the back surface 11B in the vicinity of the first and second end portions 21 and 22 may be flat, or the concave portion 17 may be provided in accordance with the first and second end portions 21 and 22.

  In the present invention using the bent hollow metal tube 20, the first end portion 21, the second end portion 22, and the C ring portion 23 are integrally formed so as not to form a gap. There is no. The cost of welding a U-shaped sheet metal to the wear-resistant ring can also be reduced. Since the first and second end portions 21 and 22 are smoothly curved toward the back surface 11B, the flow path resistance of the cooling channel 15 can be reduced. Lubricating oil can be smoothly introduced into the cooling channel 15 to improve the cooling efficiency of the piston 10.

Since the tips 21E and 22E of the hollow metal tube 20 communicate with the outside from the back surface 11B of the piston 10, when the piston 10 is cast, the gas in the tube escapes to the mold 100 facing the back surface 11B, and the cast hole by the gas Can be prevented in advance. Furthermore, the tip is open from the beginning 21E, since it can be used 22E as inlet 15 _IN and the outlet 15 _OUT of the lubricating oil can be reduced the number of steps it is not necessary to open the through-hole in the drill later. Hereinafter, each configuration will be described in detail.

  FIG. 1 is a cross-sectional view showing a schematic configuration of the internal combustion engine 1. As shown in FIG. 1, the internal combustion engine 1 includes, for example, a cylinder block 2, a piston 10 accommodated in the cylinder block 2, a crankshaft 4, and a connecting rod 5. For convenience of description of the embodiment, the bottom dead center side is defined as “lower” and the opposite side from the bottom dead center side is defined as “up” based on the reciprocating motion of the piston 10 assembled to the cylinder block 2. When the internal combustion engine 1 is disposed at an inclination, “upper” and “lower” do not necessarily coincide with the direction of gravity.

  The piston 10 is assembled to a cylinder bore 6 formed at the top of the cylinder block 2. The crankshaft 4 is assembled to a crankcase 7 formed at the lower part of the cylinder block 2. The crankcase 7 is provided with an oil jet 8 at a position that does not interfere with the crankshaft 4. The oil jet 8 injects lubricating oil toward the piston 10 as indicated by an arrow L in FIG. The piston 10 and the crankshaft 4 are connected to each other by a connecting rod 5.

[First Embodiment]
FIG. 2 is a perspective view showing an example of the piston 10 of the first embodiment. As shown in FIG. 2, the piston 10 includes a crown portion 11, a pin boss 12, a skirt portion 13, a sidewall portion 14, and a cooling channel 15. The crown portion 11 has a crown surface 11A, a back surface 11B opposite to the crown surface 11A, and an outer peripheral surface 11C that connects the crown surface 11A and the back surface 11B.

  The crown surface 11A, together with the cylinder bore 6 of the cylinder block 2, partitions the combustion chamber 9 of the internal combustion engine 1 shown in FIG. A piston groove 16 is formed on the outer peripheral surface 11C. A piston groove 16 may be formed in the wear-resistant ring by casting a wear-resistant ring on the outer peripheral surface 11C. The wear-resistant ring is formed in an annular shape from a metal having higher wear resistance than the crown portion 11.

  The back surface 11 </ b> B is located on the side opposite to the combustion chamber 9. A pair of pin bosses 12 are arranged opposite to each other on the back surface 11B. Each pin boss 12 has a pin hole 12A formed on a concentric shaft. The skirt portion 13 extends from the outer peripheral edge of the crown portion 11 toward the side opposite to the combustion chamber 9.

The sidewall portion 14 extends around the pin boss 12 and is continuous with the skirt portion 13. A cooling channel 15 is formed inside the crown portion 11. The cooling channel 15 has a lubricating oil inlet 15 _IN and an outlet 15 _OUT opened to the back surface 11B.

The inlet _15IN faces the tip of the nozzle of the oil jet 8 shown in FIG. The lubricating oil injected from the oil jet 8 is introduced to the cooling channel 15 from the inlet 15 _IN. The introduced lubricating oil flows through the cooling channel 15 to cool the piston 10, and then is discharged from the outlet 15 _OUT and falls into the oil reservoir at the bottom of the crankcase 7.

  As shown in FIG. 2, the piston 10 of this embodiment includes a hollow metal tube 20 cast into the crown portion 11. The inside of the hollow metal tube 20 is partitioned as a cooling channel 15. The hollow metal tube 20 has a first end portion 21, a second end portion 22, and a C ring portion 23. The C ring portion 23 is disposed between the crown surface 11 </ b> A and the back surface 11 </ b> B and is formed in a hollow annular shape extending in the circumferential direction of the piston 10. More specifically, the C ring portion 23 is not closed between one end and the other end, and is formed in a C shape when viewed from the combustion chamber 9.

  When the piston 10 becomes high temperature, the piston groove 16 is easily worn. The C ring portion 23 is disposed along the piston groove 16, for example. When the piston groove 16 is formed in the wear-resistant ring, the inner peripheral surface of the wear-resistant ring and the outer peripheral surface of the C ring portion may be fixed. When the internal combustion engine 1 is a diesel engine, a cavity 9A (shown in FIG. 1) that promotes combustion of diesel fuel is formed on the crown surface 11A. Since the edge of the cavity 9A is easily worn in a high temperature environment, the C ring portion 23 may be disposed in the vicinity of the cavity 9A.

  The first end portion 21 is continuous with one end of the C ring portion 23. The second end portion 22 is continuous with the other end of the C ring portion 23. The first and second end portions 21 and 22 are curved from the C ring portion 23 toward the back surface 11B. The tips 21E and 22E of the first and second end portions 21 and 22 are exposed to the outside of the piston 10 from the back surface 11B of the crown portion 11.

  The hollow metal tube 20 can be formed, for example, by bending a straight hollow metal tube. The first end portion 21, the second end portion 22, and the C ring portion 23 are integrally formed and are smoothly continuous. The first and second end portions 21 and 22 have substantially the same shape and function. Therefore, the first end portion 21 will be described in detail as a representative, and the duplicate description of the second end portion 22 may be omitted.

  FIG. 3 is a bottom view of the piston 10 shown in FIG. 4 is a cross-sectional view taken along line F4-F4 in FIG. In FIG. 4, the mold 100 transferred to the back surface 11 </ b> B is partially cut away for explanation. FIG. 5 is a modification of the first end 21 shown in FIG. The distal end 21 </ b> E of the first end portion 21 is exposed to the outside of the piston 10 from the back surface 11 </ b> B of the crown portion 11. The back surface 11B of the crown part 11 may be flat as shown in FIG. 4, or may be provided with a recess 17 as shown in FIG. The concave portion 17 is located on an extension line of the central axis of the first end portion 21.

  In the example shown in FIG. 4, the distal end 21 </ b> E of the first end portion 21 is formed with a larger diameter than the C ring portion 23. If the tip 21E has an enlarged diameter, the lubricating oil injected from the oil jet 8 can be easily introduced into the C ring portion 23. When the concave portion 17 is provided on the back surface 11B, the concave portion 17 facing the oil jet 8 may be formed in a mortar shape.

  As shown in FIGS. 4 and 5, the mold 100 includes a positioning pin 110 that is inserted into the hollow metal tube 20. The positioning pin 110 has a vent hole 110 </ b> A, and when casting the piston 10, even if the gas in the hollow metal tube 20 expands, it can escape to the outside of the piston 10. In the example shown in FIG. 5, the mold 100 further includes a convex portion 120 that is transferred to the concave portion 17. The convex portion 120 is provided at the proximal end of the positioning pin 110 and has a diameter larger than that of the positioning pin 110.

  The piston 10 of the present embodiment configured as described above includes a hollow metal tube 20 cast into the crown portion 11. Since the hollow metal tube 20 bent in the cooling channel 15 is used, the cost of welding a sheet metal having a U-shaped cross section to the wear-resistant ring can be reduced. In addition, since the first end portion 21, the second end portion 22, and the C-ring portion 23 are integrally formed and no gap is formed, there is no possibility that gas leaks from a place with poor welding.

  If a hole is formed with a drill to form an inlet and an outlet for lubricating oil, man-hours are required for drilling. In addition, the curvature greatly changes at the boundary between the through hole and the cooling channel at right angles to increase the flow resistance. If the flow path resistance is large, part of the lubricating oil will bounce off without being introduced into the cooling channel. This embodiment can eliminate those disadvantages resulting from drilling.

  The present embodiment includes first and second end portions 21 and 22 that are curved from the C ring portion 23 toward the back surface 11B. Since the first end portion 21, the second end portion 22, and the C-ring portion 23 are integrally molded and are smoothly continuous, the flow path resistance of the cooling channel 15 can be reduced. Lubricating oil can be smoothly introduced into the cooling channel 15 to improve the cooling efficiency of the piston 10.

The present embodiment includes tips 21E and 22E exposed from the back surface 11B to the outside of the piston 10. Since the tips 21E and 22E of the hollow metal tube 20 communicate with the outside from the back surface 11B of the piston 10, when the piston 10 is cast, the gas in the tube is released to the mold 100 facing the back surface 11B, and the cavity is formed by the gas. Can be prevented in advance. Furthermore, the tip is open from the beginning 21E, since it can be used 22E as inlet 15 _IN and the outlet 15 _OUT of the lubricating oil can be reduced the number of steps it is not necessary to open the through-hole in the drill later.

  Next, with reference to FIG. 6 thru | or FIG. 9, the piston 10 of 2nd and 3rd embodiment is demonstrated. In addition, the structure which has the same or similar function as the structure of 1st Embodiment attaches | subjects the same code | symbol, considers description of 1st Embodiment corresponding, and abbreviate | omits description here. Other configurations are the same as those in the first embodiment.

[Second Embodiment]
FIG. 6 is a bottom view showing an example of the piston 10 of the second embodiment. The second embodiment is different from the first embodiment in that at least one of the first and end portions 21 and 22 protrudes from the back surface 11B. The protruding first and second end portions 21 and 22 may be directed downward, or may be inclined with respect to the central axis of the piston 10, that is, the vertical direction in which the piston 10 reciprocates.

  In the example shown in FIG. 6, the second end portion 22 protrudes from the back surface 11 </ b> B and is inclined inward in the radial direction of the piston 10. The protruding end 22E of the second end 22 is located on the inner side of the circle drawn by the central axis of the C ring portion 23 and faces the piston pin 18 inserted through the pin hole 12A. The lubricating oil discharged from the tip 22E is indicated by an arrow L in FIG.

  According to the second embodiment, since the length and direction of the first and second end portions 21 and 22 can be freely adjusted, the degree of freedom in design is improved. For example, as shown in FIG. 6, when the second end 22 is inclined inward in the radial direction of the piston 10, lubricating oil discharged from the tip 22 </ b> E of the second end 22 can be supplied to the piston pin 18. The reliability of the internal combustion engine 1 can be improved by increasing the amount of lubricating oil adhering to the piston pin 18.

[Third Embodiment]
FIG. 7 is a bottom view showing an example of the piston 10 of the third embodiment. The third embodiment is different from the first embodiment in that the crown portion 11 further includes a through hole 19 penetrating from the back surface 11B to the C ring portion 23. The through-hole 19 may be one place or two or more places. In the third embodiment, in addition to the first and second end portions 21 and 22, because it has a through-hole 19, to be able to change the number and arrangement of the inlet _{15 IN} and the outlet _{15 OUT} cooling channel 15 Thus, the degree of freedom in design is improved.

FIG. 7 shows an example in which the tips 21E and 22E of the first and second end portions 21 and 22 are used as the outlet 15 _OUT at both ends, and the inlet 15 _IN is arranged by opening the through hole 19 on the opposite side to the outlet 15 _OUT. is there. The diesel engine needs to cool the piston 10 more uniformly than the gasoline engine. However, as shown in FIG. 7, if the inlets 15 _IN are arranged so that the distances from the two outlets 15 _OUT are substantially the same. , easily uniformly cool the piston 10 evenly distribute the lubricating oil introduced into the inlet 15 _iN.

  8 shows the piston 10 viewed from the direction of the arrow F8 in FIG. 7, and FIG. 9 shows the piston 10 viewed from the direction of the arrow F9 in FIG. As shown in FIGS. 8 and 9, the first and second end portions 21 and 22 of the hollow metal tube 20 are curved and smoothly connected to the C ring portion 23, whereas they are formed by drilling. The through hole 19 is orthogonal to the C ring portion 23.

In the third embodiment, since the flow path is curved in at least two of the three or more openings including the inlet 15 _IN and the outlet 15 _OUT , all the openings are configured by the through holes 19. The channel resistance can be reduced compared to the cooling channel. The lubricating oil injected from the oil jet 8 can be smoothly introduced into the cooling channel 15 to improve the cooling efficiency.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and equivalents thereof. For example, the hollow metal tube 20 may be two or more. The number of oil jets 8 may be increased in accordance with the number of hollow metal tubes 20, or the lubricating oil may be distributed by branching the nozzles of the oil jet 8.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 8 ... Oil jet, 9 ... Combustion chamber, 10 ... Piston, 11 ... Crown part, 11A ... Crown surface, 11B ... Back surface, 12 ... Pin boss, 15 ... Cooling channel, 17 ... Recessed part, 18 ... Piston pin , 19 through hole, 20 hollow metal tube, 21 first end, 21E first end, 22 second end, 22E second end, 23 C ring.

Claims (7)

A crown portion having a crown surface defining a combustion chamber of the internal combustion engine and a back surface opposite to the crown surface;
A cooling channel which is partitioned in a hollow metal tube cast into the crown portion and through which lubricating oil injected toward the back surface flows,
The hollow metal tube has an integrally formed C ring portion, a first end portion, and a second end portion,
The C ring portion is disposed between the crown surface and the back surface,
The first end and the second end are respectively continuous with one end and the other end of the C ring portion, and are respectively curved from the C ring portion toward the back surface.   2. The piston according to claim 1, wherein tips of the first end and the second end are exposed to the outside from the back surface. The back surface is formed with a recess located on an extension line of the first end and the second end, respectively, and the first end and the second end are exposed to the outside from the bottom of the recess. The piston according to claim 2.   The piston according to any one of claims 1 to 3, wherein a tip end of the first end portion faces an oil jet that injects lubricating oil toward the back surface.   The piston according to claim 4, wherein a tip end of the first end portion is formed to have a larger diameter than the C ring portion. A pair of pin bosses provided on the back surface;
The piston according to any one of claims 1 to 5, wherein a tip end of the second end portion is opposed to a piston pin inserted through the pair of pin bosses.   The piston according to any one of claims 1 to 3, wherein the crown portion further includes a through hole penetrating from the back surface to the C ring portion.

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