JP2005036690A - Piston for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston for an internal combustion engine manufacturable at low cost and enabling the secure cooling of the crown part of the piston. <P>SOLUTION: This piston for the internal combustion engine comprises a cooling channel 6 annularly formed in the crown part 1a of a piston body 1, discharge holes 7a and 7b formed in the lower surface part of the crown part 1a so as to communicate with the cooling channel 6, and a communication hole 8 formed in the lower part of the oil ring groove 3 for inserting an oil ring 5 therein so as to communicate with the cooling channel 6. In this piston, oil scraped off from the inner wall 11a of a cylinder 11 by the oil ring 5 while the piston body 1 is moved in the cylinder 11 from a top dead center to a bottom dead center is collected from the communication hole 8 into the cooling channel 6 and discharged from the discharge holes 7a and 7b so as to cool the crown part 1a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine piston, and more particularly to an internal combustion engine piston that cools a crown by forming an annular cooling channel through which oil passes in the crown of a piston body.
[0002]
[Prior art]
FIG. 3 shows a cross-sectional view of a conventional piston for an internal combustion engine, and as shown in FIG. A compression ring groove 52 a, a compression groove 52 b, and an oil ring groove 53 are formed in this order, the compression rings 54 a and 54 b are attached to the compression grooves 52 a and 52 b, respectively, and the oil ring 55 is attached to the oil ring groove 53. An annular cooling channel 56 is formed in the crown portion 51a of the piston main body 51, and introduction holes 57a and 57b that communicate with the cooling channel 56 and open to the crank chamber side are formed in the lower surface portion of the crown portion 51a. Furthermore, a communication hole 58 is formed on the outer periphery of the piston main body 51 so as to penetrate from the lower part of the oil ring groove 53 to the inside.
[0003]
In this internal combustion engine piston, oil is blown into the piston main body 51 by an oil jet or the like during operation, and a part of the oil is injected into the cooling channel 56 from the introduction holes 57a and 57b. The part 51a is cooled. On the other hand, when the piston main body 51 moves in the cylinder 59 from the top dead center side to the bottom dead center side, the oil scraped off from the inner wall 59a of the cylinder 59 by the oil ring 55 in the meantime passes through the through hole 58 to the crank chamber side. It is configured to discharge.
[0004]
Moreover, the thing of the structure shown in FIG.5 and FIG.6 is known as a piston for internal combustion engines. 5 and 6, the piston main body 61 is composed of a crown portion 61a and a skirt portion 61b. An annular cooling channel 62 is formed in the crown portion 61a, and an introduction hole is formed in the lower surface portion of the crown portion 61a. 63 is formed, and the cooling channel 62 is opened inside the piston main body 61 through the introduction hole 63, that is, toward the crank chamber side.
[0005]
A pair of pin boss portions 64 are formed in the skirt portion 61 b. A piston pin hole 65 is formed in the pin boss portion 64, and an end portion of the piston pin 66 is fitted in the piston pin hole 65. Further, ring grooves 67a and 67b are formed on the outer peripheral portion of the skirt portion 61b with the piston pin hole 65 interposed therebetween, and seal rings 68a and 68b are attached to the ring grooves 67a and 67b, respectively. An oil reservoir 78 is formed between them.
[0006]
A plurality of oil supply passages 69 are formed in the piston main body 61, and the cooling channel 62 communicates with the oil reservoir 78 through the oil supply passages 69. Furthermore, a plurality of oil relief passages 71 are formed along the axial direction of the piston pin 66 at the fitting portion between the piston pin hole 65 and the piston pin 66.
[0007]
A compression ring groove 72 and an oil ring groove 73 are formed on the outer peripheral portion of the piston main body 61 on the crown 61a side from the seal rings 68a and 68b, and a compression ring 74 is attached to the compression ring groove 72. An oil ring 75 is attached to the groove 73.
[0008]
The piston main body 61 is inserted into the cylinder 70, and the seal rings 68a and 68b, the compression ring 74, and the oil ring 75 abut against the cylinder inner wall 70a, whereby the inside of the cylinder 70 is connected to the combustion chamber 76 and the crank chamber 77. It is formed.
[0009]
5 shows a front view of the right half cross section when the piston pin 66 is not mounted in a direction perpendicular to the piston pin hole 65. FIG. 6 shows the piston pin 66 mounted state at the center of the piston pin hole 65. The front view of the right half cross section seen in the line direction is shown.
[0010]
In this internal combustion engine piston, when the internal combustion engine is operated, oil is injected into the piston main body 61 by an oil jet or the like, and a part of the oil is injected into the cooling channel 62 from the introduction hole 63. The oil thus supplied is supplied to the oil reservoir 78 via the oil supply passage 69, and the oil supplied to the oil reservoir 78 is gradually discharged to the inside of the piston body 61 via the oil escape passage 71.
[0011]
In this way, the crown 61a of the piston main body 61 is cooled by the oil injected into the cooling channel 62, and the oil between the piston main body 61 and the cylinder inner wall 70a is lubricated by the oil supplied to the oil reservoir 78. In addition, in cooperation with the compression ring 74, the combustion gas is prevented from being blown from the combustion chamber 76 to the crank chamber 77 (see, for example, Patent Document 1).
[0012]
[Patent Document 1]
Japanese Utility Model Publication No. 6-49745
[Problems to be solved by the invention]
However, the piston for the internal combustion engine shown in FIGS. 3 and 4 requires an oil jet for injecting oil into the cooling channel 56, which makes the configuration complicated and increases the cost and weight of the internal combustion engine. Concerned. In addition, oil ejected from the oil jet during high-speed rotation may not be able to be effectively injected into the cooling channel 56 from the introduction holes 57a and 57b, which may cause insufficient cooling.
[0014]
Further, the piston for an internal combustion engine disclosed in Patent Document 1 requires an oil jet or the like for injecting oil into the cooling channel 62, so that the structure becomes complicated and the cost of the entire internal combustion engine is increased. There is a concern that the internal combustion engine may increase in weight.
[0015]
In addition to the compression ring 74 and the oil ring 75, seal rings 68a and 68b for forming the oil reservoir 78 are required, and ring grooves 67a and 67b for mounting the seal rings 68a and 68b are required. Further, in the fitting portion between the piston pin hole 65 and the piston pin 66, it is necessary to form an oil relief passage 71 by forming a groove in the axial direction on the inner surface of the piston pin hole 65 or the outer surface of the piston pin 66. Therefore, there is a concern that the number of parts and the number of processing steps increase, leading to an increase in cost of the piston itself.
[0016]
Accordingly, an object of the present invention made in view of such a point is to provide a piston for an internal combustion engine that can be simplified in structure and reduced in cost and can reliably cool a piston crown.
[0017]
[Means for Solving the Problems]
The invention of the piston for an internal combustion engine according to claim 1, which achieves the above object, communicates with a cooling channel formed in an annular shape in a crown portion of the piston main body and the cooling channel formed in a lower surface portion of the crown portion. A discharge hole, a communication hole that communicates the cooling channel with a lower portion of an oil ring groove for mounting an oil ring on the outer periphery of the piston body, and the piston body moves down the top dead center side in the cylinder. The oil scraped from the inner wall of the cylinder by the oil ring while moving to the dead center side is collected into the cooling channel from the communication hole and discharged from the discharge hole, thereby removing the crown portion. It is characterized by cooling.
[0018]
According to the first aspect of the present invention, the oil scraped off by the oil ring is recovered from the communication hole to the cooling channel and then discharged from the discharge hole, so that the oil can be stably supplied into the cooling channel. Cooling of the piston crown is obtained. Further, the configuration can be simplified without requiring an oil jet or the like, and the weight and cost of the engine can be reduced.
[0019]
According to a second aspect of the present invention, in the piston for an internal combustion engine according to the first aspect, the discharge hole has a larger diameter than the communication hole.
[0020]
According to the second aspect of the present invention, the oil recovered in the cooling channel is discharged from the discharge hole having a diameter larger than that of the communication hole, so that the oil flows smoothly through the cooling channel and the cooling efficiency of the piston crown is increased. .
[0021]
According to a third aspect of the present invention, in the piston for an internal combustion engine according to the first or second aspect, the discharge holes are formed at two substantially symmetrical positions in the annular shape of the cooling channel.
[0022]
According to the invention of claim 3, since the oil collected in the cooling channel is discharged from the two discharge holes at the target position, the oil flow through the cooling channel becomes smoother, and the cooling efficiency of the piston crown is improved. More enhanced.
[0023]
According to a fourth aspect of the present invention, in the internal combustion engine piston according to any one of the first to third aspects, a plurality of the communication holes are formed at substantially equal intervals over the entire circumference of the piston body. And
[0024]
According to the invention of claim 4, since oil is collected and discharged from the entire circumference of the piston body to the cooling channel, leakage of oil from the crank chamber side to the combustion chamber side is avoided and oil consumption is suppressed. be able to. In addition, the flow of oil through the piston body is uniform and good circulation is obtained, the entire piston body is uniformly cooled, and the durability of various ring grooves formed in the piston body is improved. It is. In addition, since the entire piston body is uniformly cooled, even if the tension of the piston ring is small, the piston ring uniformly adheres to the inner wall of the cylinder and the combustion gas is surely prevented from being blown from the combustion chamber to the crank chamber. In addition, the sliding resistance between the piston ring and the cylinder inner wall can be reduced, and the output and fuel consumption are improved.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a piston for an internal combustion engine according to the present invention will be described with reference to FIGS. 1 and 2.
[0026]
FIG. 1 is a cross-sectional view showing a configuration of a main part of a piston for an internal combustion engine, and FIG. 2 is a view taken along an arrow A showing the main part of FIG.
[0027]
As shown in FIG. 1, a compression ring groove 2 a, a compression ring groove 2 b, and an oil ring groove 3 are sequentially formed on the outer periphery of the piston body 1 from the combustion chamber 15 side toward the crank chamber 16 side. Compression rings 4 a and 4 b are respectively attached to the compression ring grooves 2 a and 2 b, and an oil ring 5 is attached to the oil ring groove 3.
[0028]
In the present embodiment, an annular cooling channel 6 is formed in the crown portion 1a of the piston main body 1, and cooling is provided at two positions of the annular substantially symmetrical position of the cooling channel 6 on the lower surface portion of the crown portion 1a. Discharge holes 7a and 7b communicating with the channel 6 and opening toward the crank chamber 16 are formed.
[0029]
In addition, a large number of communication holes 8 communicating with the cooling channel 6 from the lower portion of the oil ring groove 3 are formed at the outer peripheral portion 9 of the piston body 1 at substantially equal intervals over the entire circumference. Each communication hole 8 is inclined and drilled so as to gradually move from the bottom dead center side to the top dead center side as it moves from the outer peripheral portion 9 side to the cooling channel 6 side, and has a smaller diameter than the discharge holes 7a and 7b. Is formed.
[0030]
In such a configuration, when the piston body 1 moves in the cylinder 11 from the top dead center side to the bottom dead center side, the oil is scraped off from the inner wall 11a of the cylinder 11 by the oil ring 5 and the scraped oil is After being collected in the cooling channel 6 through the communication hole 8 opened in the outer peripheral portion 9, it is discharged into the crank chamber 16 from the discharge holes 7a, 7b.
[0031]
The pressure in the gap a between the outer peripheral portion 9 of the piston body 1 below the oil ring 5 and the inner wall 11a of the cylinder 11 is increased by the speed at which the piston body 1 moves from the top dead center side to the bottom dead center side. However, since the volume in the crank chamber 16 is extremely large compared to the gap a, the inside of the crank chamber 16 does not become high pressure. Therefore, no high pressure acts on the discharge holes 7a and 7b from the crank chamber 16 side, so that the oil scraped off by the oil ring 5 smoothly enters the cooling channel 6 from the communication hole 8 formed by being inclined. And discharged from the discharge holes 7a and 7b to the crank chamber 16 side.
[0032]
Thus, in the present embodiment, the oil scraped off from the inner wall 11a of the cylinder 11 by the oil ring 5 while the piston body 1 moves from the top dead center side to the bottom dead center side in the cylinder 11 is removed. Since it is collected in the cooling channel 6 from the opening of the outer peripheral portion 9 through the communication hole 8 and discharged into the crank chamber 16 from the discharge holes 7a and 7b, the crown 1a is not required without oil jets or the like. Can be reliably cooled, making the whole compact and low cost.
[0033]
In addition, since the discharge holes 7a and 7b having a diameter larger than the diameter of the communication hole 8 are provided at two locations in the annular substantially symmetrical position of the cooling channel 6, the oil flow through the cooling channel 6 can be made smoother. The crown 1a can be efficiently cooled.
[0034]
Further, in the present embodiment, a large number of communication holes 8 are formed at almost equal intervals over the entire outer periphery of the piston body 1, and the oil scraped from the inner wall 11 a of the cylinder 11 is removed from the entire piston body 1. Since the oil is collected from the circumference to the cooling channel 6, the oil is collected and discharged from the entire circumference of the piston body 1 to the cooling channel 6, so that the oil leaks from the crank chamber 16 side to the combustion chamber 15 side. By avoiding this, oil consumption can be suppressed, and the oil flow through the piston body 1 can be made uniform, so that good circulation can be obtained. Accordingly, the entire piston body 1 can be uniformly cooled, and the durability of the various ring grooves of the compression ring grooves 2 a and 2 b and the oil ring groove 3 formed in the piston body 1 can be improved.
[0035]
Further, since the entire piston body 1 can be uniformly cooled, the compression rings 4a and 4b and the piston ring of the oil ring 5 can be uniformly adhered to the inner wall 11a of the cylinder 11 with a small tension. It is possible to surely prevent the combustion gas from being blown through, and to reduce the sliding resistance between the piston ring and the inner wall 11a of the cylinder 11, thereby improving the output and fuel consumption.
[0036]
Incidentally, when the cooling is not uniform, it is necessary to increase the tension of the compression rings 4 a and 4 b and the piston rings of the oil ring 5 in order to bring the piston ring into close contact with the inner wall of the cylinder 11. For this reason, the pressure contact force between the piston ring and the inner wall 11a of the cylinder 11 is increased, the sliding resistance is increased, which causes a decrease in output and a deterioration in fuel consumption.
[0037]
Further, the knock generation limit is improved by lowering the temperature of the crown portion 1a of the piston body 1, and a stable engine output can be secured. Moreover, the above-mentioned various effects can be obtained only by the piston body 1, and the piston body 1 can be applied to an existing engine and has excellent versatility.
[0038]
In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of invention. For example, the number of the discharge holes is not limited to two, and one or three or more discharge holes may be provided at appropriate positions, and the diameter does not necessarily need to be larger than the communication hole, and may be an arbitrary size. Further, the communication holes are not limited to being provided at substantially equal intervals over the entire circumference of the piston body, but can be formed partially biased or the number thereof can be arbitrarily set.
[0039]
【The invention's effect】
As described above, according to the present invention, the discharge channel is formed in the lower surface portion of the crown portion in communication with the cooling channel formed in the piston crown portion, and the communication hole is formed below the oil ring groove in the outer peripheral portion of the piston body. The oil scraped from the inner wall of the cylinder by the oil ring while the piston body moves from the top dead center side to the bottom dead center side in the cylinder is collected from the communication hole into the cooling channel and is discharged from the discharge hole. By discharging, it is possible to reliably cool the piston crown without requiring an oil jet or the like, and without requiring extra parts or processing, and at a low cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of a main part of a piston for an internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a view taken along arrow A in FIG.
FIG. 3 is a front view of a configuration of a conventional piston for an internal combustion engine.
4 is a view taken in the direction of arrow B in FIG. 3;
FIG. 5 is a front view of a right half cross section viewed in a direction perpendicular to a piston pin hole in a state in which a piston pin is not mounted, showing the configuration of another conventional internal combustion engine piston.
FIG. 6 is a front view of the right half section viewed in the direction of the center line of the piston pin hole when the piston pin is mounted.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Piston main body 1a Crown part 2a, 2b Compression ring groove 3 Oil ring groove 4a, 4b Compression ring 5 Oil ring 6 Cooling channel 7a, 7b Discharge hole 8 Communication hole 11 Cylinder 11a Inner wall

Claims (4)

A cooling channel formed annularly in the crown of the piston body;
A discharge hole communicating with the cooling channel formed on the lower surface of the crown,
A communication hole that communicates the lower part of the oil ring groove for mounting the oil ring on the outer periphery of the piston body and the cooling channel;
While the piston body moves from the top dead center side to the bottom dead center side in the cylinder, the oil scraped from the inner wall of the cylinder by the oil ring is collected in the cooling channel through the communication hole. Then, the piston for the internal combustion engine, wherein the crown portion is cooled by being discharged from the discharge hole. The piston for an internal combustion engine according to claim 1, wherein the discharge hole has a larger diameter than the communication hole. 3. The piston for an internal combustion engine according to claim 1, wherein the discharge holes are formed at two positions of an annular substantially symmetrical position of the cooling channel. 4. The piston for an internal combustion engine according to any one of claims 1 to 3, wherein a plurality of the communication holes are formed at substantially equal intervals over the entire circumference of the piston body.

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