JP2014136993A - Piston and internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston capable of suppressing the twist of a piston ring during abnormal combustion in an internal combustion engine, and to provide an internal combustion engine.SOLUTION: A piston 30 of an internal combustion engine includes a communication passage 44 for communicating a piston top surface 34 with a top ring groove 31 in which a top ring 41 is stored. At least a portion of a groove side opening part 46 where the communication passage 44 is opened to the top ring groove 31 is located further inside in a piston radial direction than a site where an inner peripheral face 41A of the top ring 41 is to be located when the top ring 41 is stored in the top ring groove 31.

Description

  The present invention relates to a piston for an internal combustion engine and an internal combustion engine having the piston.

In an internal combustion engine, when abnormal combustion such as knocking or pre-ignition occurs, a situation may occur in which the pressure in the combustion chamber locally increases.
Patent Document 1 discloses, as an example of measures against such a situation, forming a groove having an end opened to the top surface of the piston on the outer peripheral side surface of the top land. In this piston, even if abnormal combustion occurs and the pressure in the combustion chamber rises locally, and the pressure wave generated thereby enters the gap between the outer peripheral side surface of the top land and the cylinder bore, the pressure wave passes through the groove to the piston. To the combustion chamber above. Therefore, it is possible to suppress the pressure wave entering the gap between the top land outer peripheral side surface and the cylinder bore from propagating through the gap and concentrating on a part of the top land outer peripheral side surface.

JP 2012-117501 A

  By the way, as described above, during abnormal combustion of the internal combustion engine, a situation may occur in which the pressure in the combustion chamber locally increases. And when the pressure in a combustion chamber becomes high locally, there exists a possibility that a piston may slide in the state which inclined in the cylinder, and the piston ring with which the piston's ring groove was mounted may twist.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a piston and an internal combustion engine that can suppress the piston ring from being twisted during abnormal combustion of the internal combustion engine.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A piston for solving the above-described problems includes a communication passage that communicates a piston top surface and a ring groove in which a piston ring is accommodated, and at least one of openings that open to the ring groove of the communication passage. When the piston ring is accommodated in the ring groove, the portion is located on the inner side in the piston radial direction than the portion where the inner peripheral surface of the piston ring is located.

  According to the above configuration, high-pressure combustion gas generated during abnormal combustion of the internal combustion engine is supplied to the inner side of the inner peripheral surface of the piston ring in the ring groove through the communication path. Therefore, the piston ring can be pressed from the inner peripheral side toward the outer peripheral side by the pressure of the combustion gas. Thereby, since a piston ring can be pressed on a cylinder bore, it can suppress that a piston ring twists.

In addition, since high pressure due to abnormal combustion can be released from the combustion chamber through the communication path, it is possible to suppress high pressure from acting on the top land.
In the piston, it is preferable that at least a part of the opening is located on a bottom surface of the ring groove.

  According to the above configuration, high-pressure combustion gas is supplied to the ring groove from the bottom surface side of the ring groove. Therefore, the pressure of the combustion gas acts to press the piston ring from the bottom surface side of the ring groove. Therefore, the piston ring can be pressed more suitably from the inner peripheral side toward the outer peripheral side by the pressure of the combustion gas, and the piston ring can be pressed against the cylinder bore.

  Furthermore, when at least a part of the opening is located on the bottom surface of the ring groove, the portion of the passage wall of the communication passage that is connected to the bottom surface of the ring groove is separated from the top surface of the piston. It is preferable to be inclined so as to be separated from the piston central axis.

  Further, in the piston, the piston wall is located closer to the piston center axis than the portion of the passage wall of the communication passage where the inner peripheral surface of the piston ring is located when the piston ring is accommodated in the ring groove. It is preferable that the portion located and connected to the ring groove is inclined so as to be separated from the piston central axis as it approaches the ring groove.

  When the passage wall is inclined in the above-described manners, the combustion gas introduced from the combustion chamber into the communication passage is rectified in the direction from the inner side to the outer side of the ring groove at the inclined portion of the passage wall. Is supplied to the ring groove. Therefore, the pressure of the combustion gas can be applied so as to more suitably press the piston ring in the direction from the inner peripheral side to the outer peripheral side, and therefore, the piston ring can be more preferably pressed against the cylinder bore.

  Further, in each of the pistons, a part of the opening is located on the outer side in the piston radial direction from a portion where the inner peripheral surface of the piston ring is located when the piston ring is accommodated in the ring groove. Preferably it is located.

  The ring groove has two side surfaces that face each other across the bottom surface and the bottom surface. In the above configuration, high-pressure combustion gas is supplied from the side surface located on the piston top surface side in the ring groove at the time of abnormal combustion, and the pressure of the combustion gas flows from the piston top surface side to the side opposite to the top surface. It acts to press in the direction toward the side. Therefore, the piston ring can be pressed against the side surface opposite to the piston top surface in the ring groove. In this way, since the piston ring is pressed against both the cylinder bore and the side surface of the ring groove, it is possible to more suitably suppress the twist of the piston ring.

  In each piston, the piston top surface has an intake valve recess formed in one of the two regions divided by a straight line passing through the piston central axis, and an exhaust valve recess formed in the other region. The communication path is preferably located in a region where the intake valve recess is formed.

  Local pressure increase due to abnormal combustion is more likely to occur on the intake valve side than on the exhaust valve side. Therefore, when abnormal combustion occurs, the intake valve side of the piston is inclined downward than the exhaust valve side. In this regard, according to the above configuration, since the communication passage is provided on the intake valve side of the piston, high pressure generated on the intake valve side of the combustion chamber during abnormal combustion is released through the communication passage and the pressure is used. Thus, the piston ring can be pressed down to prevent the piston ring from being twisted.

  Further, in each of the pistons, a plurality of intake valve recesses are formed on the piston top surface, and an opening portion in which the communication path opens on the piston top surface is formed by a squish formed between adjacent intake valve recesses. It is possible to adopt an aspect such as being located in the part.

In each of the above pistons, it is possible to employ a configuration in which a plurality of ring grooves are provided, and the communication passage communicates the piston top surface and the ring groove closest to the piston top surface.
Moreover, the internal combustion engine for solving the said subject is provided with the piston in any one of said each structure.

The schematic diagram which shows an internal combustion engine provided with the piston concerning 1st Embodiment. The top view of the piston concerning the embodiment. (A) is the fragmentary sectional view in the 3-3 line of FIG. 2, (b) is an enlarged view which expands and shows a part of (a). Sectional drawing which expands and shows a part of piston concerning 2nd Embodiment. Sectional drawing which expands and shows a part of piston concerning 3rd Embodiment. Sectional drawing which expands and shows a part of piston concerning 4th Embodiment. Sectional drawing which expands and shows a part of piston concerning 5th Embodiment. Sectional drawing which expands and shows a part of piston concerning 6th Embodiment. The top view of the piston concerning other embodiments.

(First embodiment)
Hereinafter, a first embodiment of a piston and an internal combustion engine will be described in detail with reference to FIGS. The internal combustion engine of this embodiment is a gasoline engine provided with a supercharger.

  As shown in FIG. 1, a throttle valve 12 is provided in the intake passage 11 of the internal combustion engine 10. In the internal combustion engine 10, the amount of air taken into the combustion chamber 15 is adjusted by adjusting the opening degree of the throttle valve 12.

  A piston 30 is provided in the cylinder 14 of the internal combustion engine 10. A top ring groove 31, a second ring groove 32, and an oil ring groove 33 are formed in the piston 30 in order from the piston top surface 34 side. A top ring 41 is attached to the top ring groove 31, a second ring 42 is attached to the second ring groove 32, and an oil ring 43 is attached to the oil ring groove 33. The configuration of the piston 30 will be described later in detail.

  The internal combustion engine 10 is provided with a fuel injection valve 13 so as to face the combustion chamber 15. The fuel injection valve 13 injects fuel into the combustion chamber 15 as the valve is opened. A spark plug 17 is provided in the cylinder head 16 so as to face the combustion chamber 15. In the internal combustion engine 10, the fuel injected from the fuel injection valve 13 burns in the combustion chamber 15, whereby the piston 30 reciprocates and the crankshaft 18 rotates. The gas after combustion is sent out from the combustion chamber 15 to the exhaust passage 19 as exhaust.

  The intake passage 11 and the combustion chamber 15 are communicated and blocked by opening and closing the intake valve 21, and the exhaust passage 19 and the combustion chamber 15 are communicated and blocked by opening and closing the exhaust valve 22. Two intake valves 21 and two exhaust valves 22 are provided for each cylinder 14.

  The internal combustion engine 10 is provided with a supercharger 25 that pumps intake air in the intake passage 11. Specifically, a compressor 26 of the supercharger 25 is attached to the upstream side of the throttle valve 12 in the intake passage 11. A turbine 27 of the supercharger 25 is attached to the exhaust passage 19 of the internal combustion engine 10. The supercharger 25 is of an exhaust drive type in which a compressor wheel 26A provided inside the compressor 26 and a turbine wheel 27A provided inside the turbine 27 are connected. In the exhaust passage 19, the upstream side and the downstream side of the turbine 27 are connected by a bypass passage 28, and a waste gate valve 29 is provided in the bypass passage 28. By adjusting the opening degree of the waste gate valve 29, the flow rate of the exhaust gas blown to the turbine wheel 27A is changed, and the supercharging pressure by the supercharger 25 is adjusted.

  Here, in a gasoline engine equipped with a supercharger, when abnormal combustion such as knocking or pre-ignition occurs, the pressure in the combustion chamber 15 is locally higher on the intake valve 21 side than on the exhaust valve 22 side. Things can happen. When the pressure in the combustion chamber 15 locally increases in this way, the piston 30 slides in an inclined state in the cylinder 14, so that the piston ring mounted in the ring groove of the piston 30 may be twisted. There is.

  Therefore, as shown in FIGS. 2 and 3, the piston 30 of the present embodiment includes a communication passage 44 that allows the piston top surface 34 and the top ring groove 31 to communicate with each other. By causing the high-pressure combustion gas generated during abnormal combustion to act on the top ring 41, twisting of the top ring 41 is suppressed.

Hereinafter, the piston 30 and the communication passage 44 formed in the piston 30 will be described in detail with reference to FIGS. 2 and 3.
As shown in FIG. 2, two intake valve recesses 35 are formed in one region of the two regions divided by a straight line L passing through the piston central axis C, and two piston valve surfaces 35 are formed in the other region. An exhaust valve recess 36 is formed. Each of the valve recesses 35 and 36 is a recess for avoiding contact of the piston top surface 34 with the intake valve 21 or the exhaust valve 22 when the piston 30 is displaced. Further, a squish portion 37 is formed on the peripheral portion of the piston top surface 34 to push out the air-fuel mixture by narrowing the gap between the piston 30 and the cylinder head 16 when the piston 30 approaches the top dead center. ing. The communication path 44 is located in an area where the intake valve recess 35 is formed, of the two areas divided by the straight line L. The top surface side opening 45 where the communication path 44 opens to the piston top surface 34 is located in the squish portion 37 between the two intake valve recesses 35.

  As shown in FIG. 3, the top ring groove 31 includes a bottom surface 31A and side surfaces 31B and 31C that face each other with the bottom surface 31A interposed therebetween. In the communication path 44, the groove side opening 46 opened in the top ring groove 31 is located across the bottom surface 31A and the side surface 31B located on the piston top surface 34 side. That is, a part of the groove-side opening 46 is located on the bottom surface 31 </ b> A of the top ring groove 31, so that it is located on the inner side in the piston radial direction from the inner peripheral surface 41 </ b> A of the top ring 41. Further, a part of the groove side opening 46 is located on the side surface 31B of the top ring groove 31, and a part of the groove side opening 46 formed on the side surface 31B is an inner peripheral surface of the top ring 41. It is located on the outer side in the piston radial direction than 41A. And the site | part connected to the bottom face 31A of the top ring groove 31 among the channel walls 47 of the communicating path 44 is the inclined surface 47A. The inclined surface 47A is inclined so as to be separated from the piston center axis C as the distance from the piston top surface 34 increases.

The operation of the internal combustion engine 10 and the piston 30 of this embodiment will be described.
When abnormal combustion occurs in the internal combustion engine 10, the combustion pressure in the combustion chamber 15 is locally higher on the intake valve 21 side than on the exhaust valve 22 side. As a result, the piston 30 is inclined so that the side of the piston 30 where the intake valve recess 35 is formed is positioned below the side where the exhaust valve recess 36 is formed.

  Under such circumstances, the high-pressure combustion gas in the combustion chamber 15 is supplied to the top ring groove 31 through the communication passage 44. Specifically, as shown by an arrow A in FIG. 3, the combustion gas flows along the inclined surface 47 </ b> A of the passage wall 47 when flowing in the communication passage 44, so that the top ring groove 31 moves from the inside to the outside. It is rectified in the direction toward it and supplied to the top ring groove 31 from the bottom surface 31 </ b> A side of the top ring groove 31. Therefore, the pressure of the combustion gas acts so as to press the top ring 41 in the direction from the inner peripheral side toward the outer peripheral side, so that the top ring 41 is pressed against the cylinder bore 14A side. Further, as shown by the arrow B, the pressure of the combustion gas acts so as to press the top ring 41 from the piston top surface 34 side (upward in FIG. 3). It is pressed against the side surface 31C opposite to the surface 34 side. In this way, the top ring 41 is pressed against both the cylinder bore 14A and the side surface 31C of the top ring groove 31 by the pressure of the combustion gas, so that the twist of the top ring 41 is suppressed.

According to 1st Embodiment explained in full detail above, there can exist the following effects.
(1) The piston 30 of the internal combustion engine 10 of the present embodiment includes a communication passage 44 that communicates the piston top surface 34 and the top ring groove 31 in which the top ring 41 is accommodated. A part of the groove-side opening 46 of the communication path 44 has a piston diameter larger than a portion where the inner peripheral surface 41A of the top ring 41 is located when the top ring 41 is accommodated in the top ring groove 31. It is located inside the direction.

  As a result, the high-pressure combustion gas generated during abnormal combustion of the internal combustion engine 10 is supplied to the inner side of the inner peripheral surface 41A of the top ring 41 through the communication passage 44, so that the top ring 41 is moved to the inner peripheral side by the pressure of the combustion gas. Can be pressed toward the outer peripheral side. Thereby, since the top ring 41 can be pressed against the cylinder bore 14A, it is possible to suppress the top ring 41 from being twisted.

Further, since high pressure due to abnormal combustion can be released from the combustion chamber 15 through the communication passage 44, it is possible to suppress the high pressure from acting on the top land.
(2) In the piston 30 of the present embodiment, a part of the groove side opening 46 is located on the bottom surface 31 </ b> A of the top ring groove 31. Thereby, since the high-pressure combustion gas is supplied to the top ring groove 31 from the bottom surface 31 </ b> A side of the top ring groove 31, the pressure by the combustion gas presses the top ring 41 from the bottom surface 31 </ b> A side of the top ring groove 31. Works. Therefore, the top ring 41 can be suitably pressed from the inner peripheral side to the outer peripheral side by the pressure of the combustion gas, and the top ring 41 can be pressed against the cylinder bore 14A.

  (3) In the piston 30 of the present embodiment, a portion of the passage wall 47 of the communication passage 44 that is connected to the bottom surface 31A of the top ring groove 31 is an inclined surface 47A, and the inclined surface 47A is formed from the piston top surface 34. The further away, the more inclined it is from the piston central axis. As a result, the combustion gas introduced from the combustion chamber 15 into the communication passage 44 flows along the inclined surface 47A, and is then rectified in the direction from the inner side to the outer side in the piston radial direction and then supplied to the top ring groove 31. The Accordingly, the pressure of the combustion gas supplied to the top ring groove 31 acts so as to press the top ring 41 in the direction from the inner peripheral side toward the outer peripheral side, so that the top ring 41 is suitably pressed against the cylinder bore 14A. You can guess.

  (4) In the piston 30 of this embodiment, when the top ring 41 is accommodated in the top ring groove 31, the inner peripheral surface 41 </ b> A of the top ring 41 is positioned in a part of the groove side opening 46. It is located on the outer side in the piston radial direction than the part. Thereby, since combustion gas is also introduced into the top ring groove 31 from the piston top surface 34 side with respect to the top ring 41, the top ring 41 is opposite to the piston top surface 34 side in the top ring groove 31. It can be pressed against the side surface 31C. In this manner, the top ring 41 is pressed against both the cylinder bore 14A and the side surface 31C of the top ring groove 31, so that the torsion of the top ring 41 can be more suitably suppressed.

  (5) In the present embodiment, the communication passage 44 is located in a region where the intake valve recess 35 is formed, out of two regions divided by a straight line L passing through the piston central axis C. Since a local pressure increase due to abnormal combustion is more likely to occur on the intake valve 21 side than on the exhaust valve 22 side, the intake valve 21 side of the piston 30 tends to tilt downward. In this regard, according to the present embodiment, since the communication passage 44 is provided on the intake valve 21 side of the piston 30, high pressure generated on the intake valve 21 side of the combustion chamber 15 during abnormal combustion is released through the communication passage 44. be able to. Further, the top ring 41 can be pressed against the cylinder bore 14 </ b> A or the side surface 31 </ b> C of the top ring groove 31 by using the pressure to suppress the twisting of the top ring 41.

(Second Embodiment)
Next, a second embodiment of the piston and the internal combustion engine will be described with reference to FIG. The internal combustion engine of the present embodiment is provided with a piston 50 shown in FIG. The internal combustion engine of the present embodiment is the same as that of the first embodiment except for the configuration of the piston 50.

  As shown in FIG. 4, the piston 50 includes a communication passage 54 that communicates the piston top surface 51 and the top ring groove 53. A top surface side opening 55 in which the communication passage 54 opens in the piston top surface 51 is located in the squish portion 52 between the two intake valve recesses. Further, the groove-side opening 56 in which the communication path 54 is opened in the top ring groove 53 is located only on the side surface 53 </ b> B of the top ring groove 53. That is, in this embodiment, unlike the communication path 44 of the first embodiment, the groove-side opening 56 is not located on the bottom surface 53 </ b> A of the top ring groove 53.

  A part of the groove side opening 56 is located on the inner side in the piston radial direction from the inner peripheral surface 59 </ b> A of the top ring 59. A part of the groove-side opening 56 is located on the outer side in the piston radial direction from the inner peripheral surface 59 </ b> A of the top ring 59.

  At the time of abnormal combustion of the internal combustion engine, the pressure of the combustion chamber is higher on the intake valve side than on the exhaust valve side, so that the piston 50 is inclined. Under such circumstances, high-pressure combustion gas due to abnormal combustion is supplied from the combustion chamber to the top ring groove 53 through the communication passage 54. Therefore, as indicated by an arrow A, the pressure of the combustion gas acts on the inner side of the inner peripheral surface 59A of the top ring 59, so that the top ring 59 is pressed in the direction from the inner peripheral side toward the outer peripheral side. Further, as shown by an arrow B, the pressure of the combustion gas acts to press the top ring 59 in a direction from the piston top surface 51 side (upward in FIG. 4) toward the side surface 53C. Accordingly, the top ring 59 is pressed against the cylinder bore 14 </ b> A and the side surface 53 </ b> C of the top ring groove 53. Thus, also in this embodiment, the same effects as (1), (4), and (5) in the first embodiment can be obtained.

(Third embodiment)
Next, a third embodiment of the piston and the internal combustion engine will be described with reference to FIG. The internal combustion engine of the present embodiment is provided with a piston 60 shown in FIG. The internal combustion engine of the present embodiment is the same as that of the first embodiment except for the configuration of the piston 60.

  As shown in FIG. 5, the piston 60 includes a communication passage 64 that communicates the piston top surface 61 and the top ring groove 63. The top surface side opening 65 in which the communication path 64 is opened in the piston top surface 61 is located in the squish portion 62 between the two intake valve recesses. Further, the groove side opening 66 in which the communication path 64 is opened in the top ring groove 63 is located only on the bottom surface 63 </ b> A of the top ring groove 63. That is, in this embodiment, unlike the communication path 44 of the first embodiment, the groove-side opening 66 is not located on the side surface 63B of the top ring groove 63. Therefore, the entire region of the groove-side opening 66 is located on the inner side in the piston radial direction from the inner peripheral surface 69 </ b> A of the top ring 69. Further, in the passage wall 67 of the communication passage 64, a part of the portion connected to the bottom surface 63 </ b> A of the top ring groove 63 is an inclined surface 67 </ b> A, and the inclined surface 67 </ b> A is separated from the piston top surface 61. It is inclined so as to be separated from the central axis.

  At the time of abnormal combustion of the internal combustion engine, the pressure in the combustion chamber is higher on the intake valve side than on the exhaust valve side, so that the piston 60 is inclined. Under such circumstances, high-pressure combustion gas due to abnormal combustion is supplied from the combustion chamber to the top ring groove 63 through the communication path 64. As a result, as indicated by an arrow A, the pressure of the combustion gas acts to press the top ring 69 from the inner peripheral side toward the outer peripheral side, so that the top ring 69 is pressed against the cylinder bore 14A. Therefore, also in the present embodiment, the same effects as (1) to (3) and (5) in the first embodiment can be obtained.

(Fourth embodiment)
Next, a fourth embodiment of the piston and the internal combustion engine will be described with reference to FIG. The internal combustion engine of this embodiment is provided with a piston 70 shown in FIG. The internal combustion engine of the present embodiment is the same as that of the first embodiment except for the piston 70.

  As shown in FIG. 6, the piston 70 includes a communication passage 74 that communicates the piston top surface 71 and the top ring groove 73. The top surface side opening 75 in which the communication passage 74 opens in the piston top surface 71 is located in the squish portion 72 between the two intake valve recesses. Further, the groove side opening 76 in which the communication path 74 is opened in the top ring groove 73 is located only on the side surface 73 </ b> B of the top ring groove 73. That is, in the present embodiment, unlike the communication path 44 of the first embodiment, the groove side opening 76 is not located on the bottom surface 73 </ b> C of the top ring groove 73. Further, the entire region of the groove side opening 76 is located on the inner side in the piston radial direction than the inner peripheral surface 79 </ b> A of the top ring 79.

  At the time of abnormal combustion of the internal combustion engine, the pressure in the combustion chamber is higher on the intake valve side than on the exhaust valve side, so that the piston 70 is inclined. In such a situation, high-pressure combustion gas due to abnormal combustion is supplied from the combustion chamber to the top ring groove 73 through the communication passage 74, and the high pressure of the combustion gas is applied to the inner periphery of the top ring 79 as indicated by arrow A. Act on the side. Therefore, the top ring 79 is pressed against the cylinder bore 14A by being pressed in the direction from the inner peripheral side to the outer peripheral side of the top ring 79 by the pressure of the combustion gas. Therefore, also in this embodiment, the same effects as (1) and (5) in the first embodiment can be obtained.

(Fifth embodiment)
Next, a fifth embodiment of the piston and the internal combustion engine will be described with reference to FIG. The internal combustion engine of the present embodiment is provided with a piston 80 shown in FIG. The internal combustion engine of the present embodiment is the same as that of the first embodiment except for the piston 80.

  As shown in FIG. 7, the piston 80 includes a communication passage 84 that allows the piston top surface 81 and the top ring groove 83 to communicate with each other. The top surface side opening 85 in which the communication passage 84 opens at the piston top surface 81 is located in the squish portion 82 between the two intake valve recesses. Further, the groove side opening 86 in which the communication path 84 is open to the top ring groove 83 is located only on the side surface 83 </ b> B of the top ring groove 83. That is, in the present embodiment, unlike the communication path 44 of the first embodiment, the groove side opening 86 is not located on the bottom surface 83 </ b> A of the top ring groove 83. A part of the groove side opening 86 is located on the inner side in the piston radial direction from the inner peripheral surface 89 </ b> A of the top ring 89. Further, a part of the groove side opening 86 is located on the outer side in the piston radial direction from the inner peripheral surface 89 </ b> A of the top ring 89. Further, in the passage wall 87 of the communication passage 84, when the top ring 89 is accommodated in the top ring groove 83, the piston center axis side is closer to the portion where the inner peripheral surface 89 </ b> A of the top ring 89 is located. A portion that is located and connected to the bottom surface 83A of the top ring groove 83 is an inclined surface 87A. The inclined surface 87A is inclined so as to be separated from the piston central axis as it approaches the top ring groove 83.

  At the time of abnormal combustion of the internal combustion engine, the pressure of the combustion chamber is higher on the intake valve side than on the exhaust valve side, so that the piston 80 is inclined. Under such circumstances, high-pressure combustion gas due to abnormal combustion is supplied from the combustion chamber to the top ring groove 83 through the communication passage 84. As a result, the pressure of the combustion gas acts so as to press the top ring 89 from the inner peripheral side toward the outer peripheral side as indicated by the arrow A, and the pressure of the combustion gas increases as indicated by the arrow B. 59 is pressed in the direction from the piston top surface 81 side (upper side in FIG. 7) toward the side surface 83C. Accordingly, the top ring 89 is pressed against the cylinder bore 14 </ b> A and the side surface 83 </ b> C of the top ring groove 83. Therefore, also in this embodiment, the same effects as (1), (4), and (5) in the first embodiment and the following effect (6) can be obtained.

  (6) Of the passage wall 87 of the communication passage 84, when the top ring 89 is accommodated in the top ring groove 83, the piston central axis side is closer to the portion where the inner peripheral surface 89A of the top ring 89 is located. A portion located and connected to the top ring groove 83 is an inclined surface 87A. The inclined surface 87A is inclined so as to be separated from the piston center axis as it approaches the top ring groove 83. As a result, the combustion gas introduced into the communication passage 84 from the piston top surface 81 is rectified in a direction from the inner side to the outer side of the top ring groove 83 on the inclined surface 87A of the passage wall 87 and then supplied to the top ring groove 83. Is done. Therefore, the pressure of the combustion gas acts so as to press the top ring 89 in the direction from the inner peripheral side toward the outer peripheral side, so that the top ring 89 can be more suitably pressed against the cylinder bore 14A.

(Sixth embodiment)
Next, a sixth embodiment of the piston and the internal combustion engine will be described with reference to FIG. The internal combustion engine of the present embodiment is provided with a piston 90 shown in FIG. The internal combustion engine of the present embodiment is the same as that of the first embodiment except for the configuration of the piston 90.

  As shown in FIG. 8, the piston 90 includes two communication passages 94 and 95 that allow the piston top surface 91 and the top ring groove 93 to communicate with each other. That is, in the present embodiment, unlike the above-described embodiments, the communication passages 94 and 95 that form a pair of two pistons 90 are formed.

  The first communication path 94 of the two communication paths 94 and 95 is located on the inner side in the piston radial direction than the second communication path 95. The top surface side openings 94A and 95A in which the communication passages 94 and 95 are opened in the piston top surface 91 are located in the squish portion 92 between the two intake valve recesses.

  The first groove side opening 94 </ b> B in which the first communication path 94 is opened in the top ring groove 93 is located on the bottom surface 93 </ b> A of the top ring groove 93. Therefore, the first groove side opening 94B is located on the inner side in the piston radial direction than the inner peripheral surface 99A of the top ring 99. Further, in the passage wall 97 of the first communication passage 94, a part of the portion connected to the bottom surface 93A of the top ring groove 93 is an inclined surface 97A. The inclined surface 97A is inclined so as to be separated from the piston central axis as the distance from the piston top surface 91 increases.

  Further, the second groove side opening 95 </ b> B in which the second communication path 95 is open to the top ring groove 93 is located on the side surface 93 </ b> B of the top ring groove 93. A part of the second groove side opening 95B is located on the outer side in the piston radial direction than the inner peripheral surface 99A of the top ring 99.

  At the time of abnormal combustion of the internal combustion engine, the pressure of the combustion chamber is higher on the intake valve side than on the exhaust valve side, so that the piston 90 is inclined. Under such circumstances, high-pressure combustion gas due to abnormal combustion is supplied from the combustion chamber to the top ring groove 93 through the communication passages 94 and 95. Thereby, as shown by the arrow A, the pressure of the combustion gas acts so as to press the top ring 99 from the inner peripheral side toward the outer peripheral side, and as shown by the arrow B, the pressure of the combustion gas becomes higher. 99 acts in the direction from the piston top surface 91 side (upward in FIG. 9) toward the side surface 93C. Accordingly, the top ring 89 is pressed against the cylinder bore 14 </ b> A and the side surface 83 </ b> C of the top ring groove 83. Thus, also in the present embodiment, the same effects as (1) to (5) in the first embodiment can be obtained.

(Other embodiments)
In addition, in each said embodiment, you may make it change suitably as follows.
In each of the first to fifth embodiments, the piston is provided with one communication passage. For example, as shown in FIG. 9, the piston 100 is formed with the intake valve recess 104 in the piston 100. A plurality of communication passages 105 may be provided in the area. In this case, each of the plurality of communication paths 105 is provided, for example, in the same manner as any communication path in each of the above embodiments. In the sixth embodiment, the piston is provided with a set of communication paths arranged in the piston radial direction. However, the piston is provided with a plurality of communication paths similar to the communication paths of the sixth embodiment. It may be.

  In each of the above embodiments, the piston includes a communication path that connects the piston top surface and the top ring groove. However, in addition to the communication path that connects the piston top surface and the top ring groove, or in place of the communication path that connects the piston top surface and the top ring groove, the piston top surface and the second ring groove or oil ring groove You may make it provide the communicating path which connects. In this case, twisting of the second ring and the oil ring can be suppressed by configuring these communication paths to have the same configuration as any of the communication paths in the above-described embodiments. Note that the number of piston ring grooves is not limited to three. In such a case as well, a communication path that connects the ring groove formed in the piston and the piston top surface is the same as in any of the above embodiments. You may make it form in an aspect.

  In each of the above embodiments, two intake valve recesses, two exhaust valve recesses, and a squish portion are provided on the piston top surface, but the shape of the piston top surface is not limited to such a shape. For example, the number of intake valve recesses and exhaust valve recesses only needs to correspond to the number of intake valves and exhaust valves provided corresponding to each cylinder, and the number is not limited to two. Moreover, the structure which the intake valve recess, the exhaust valve recess, and the squish part are not provided in the piston top surface may be sufficient. Even in such a case, in the internal combustion engine in which the pressure on the intake valve side is locally increased during abnormal combustion, it is only necessary that a communication path similar to any one of the above embodiments is provided on the intake valve side. . Further, the communication path is not limited to the one located in the region on the intake valve side of the piston, and the same communication as in any of the above embodiments is provided on the side where the pressure of the combustion gas in the combustion chamber is locally increased by the internal combustion engine. The passage only needs to be provided on the intake valve side. Further, the internal combustion engine is not limited to the cylinder injection type gasoline engine, and may be a port injection type gasoline engine.

  -The communication path in each said embodiment is a site | part where the inner peripheral surface of the piston ring will be located when at least one part of the opening part opened to the ring groove is accommodated in a ring groove As long as it is located on the inner side in the piston radial direction, the specific shape is not particularly limited to the shape exemplified above. Moreover, you may make it combine suitably the channel | path shape etc. which were illustrated to each said embodiment.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Intake passage, 12 ... Throttle valve, 13 ... Fuel injection valve, 14 ... Cylinder, 14A ... Cylinder bore, 15 ... Combustion chamber, 16 ... Cylinder head, 17 ... Spark plug, 18 ... Crankshaft, 19 DESCRIPTION OF SYMBOLS ... Exhaust passage, 21 ... Intake valve, 22 ... Exhaust valve, 25 ... Supercharger, 26 ... Compressor, 26A ... Compressor wheel, 27 ... Turbine, 27A ... Turbine wheel, 28 ... Bypass passage, 29 ... Wastegate valve, 30 , 50, 60, 70, 80, 90, 100 ... piston, 31, 53, 63, 73, 83, 93 ... top ring groove, 31A, 53A, 63A, 73A, 83A, 93A ... bottom surface, 31B, 31C, 53B , 53C, 63B, 63C, 73B, 73C, 83B, 83C, 93B, 93C side surface, 32. End ring groove, 33 ... Oil ring groove, 34, 51, 61, 71, 81, 91 ... Piston top surface, 35, 104 ... Intake valve recess, 36 ... Exhaust valve recess, 37, 52, 62, 72, 82, 92 ... Squish Part, 41, 59, 69, 79, 89, 99 ... top ring, 41A, 59A, 69A, 79A, 89A, 99A ... inner peripheral surface, 42 ... second ring, 43 ... oil ring, 44, 54, 64, 74 , 84, 94, 95, 105 ... communication path, 45, 55, 65, 75, 85, 94A, 95A ... top side opening, 46, 56, 66, 76, 86, 94B, 95B ... groove side opening 47, 67, 87, 97 ... passage walls, 47A, 67A, 87A, 97A ... inclined surfaces.

Claims (9)

A piston having a communication path communicating with the piston top surface and a ring groove in which the piston ring is accommodated;
At least a part of the opening of the communication passage that opens in the ring groove is more piston than the portion where the inner peripheral surface of the piston ring is located when the piston ring is accommodated in the ring groove. Piston located radially inside.   The piston according to claim 1, wherein at least a part of the opening is located on a bottom surface of the ring groove.   3. The piston according to claim 2, wherein a portion of the passage wall of the communication passage that is connected to the bottom surface of the ring groove is inclined so as to be separated from the piston central axis as being separated from the piston top surface.   Of the passage walls of the communication passage, when the piston ring is housed in the ring groove, the piston ring is located closer to the piston center axis than the portion where the inner peripheral surface of the piston ring is located, and the ring groove 3. The piston according to claim 1, wherein a portion connected to is inclined so as to be separated from the piston central axis as it approaches the ring groove.   A part of the opening is located on the outer side in the piston radial direction from a portion where an inner peripheral surface of the piston ring is located when the piston ring is accommodated in the ring groove. The piston according to any one of 4. On the piston top surface, an intake valve recess is formed in one of the two regions divided by a straight line passing through the piston central axis, and an exhaust valve recess is formed in the other region.
The piston according to any one of claims 1 to 5, wherein the communication path is located in a region where the intake valve recess is formed. Plural intake valve recesses are formed on the piston top surface.
The piston according to any one of claims 1 to 6, wherein an opening portion in which the communication passage is open to a piston top surface is located in a squish portion formed between adjacent intake valve recesses. With multiple ring grooves,
The piston according to any one of claims 1 to 7, wherein the communication path communicates a piston top surface and a ring groove closest to the piston top surface.   An internal combustion engine comprising the piston according to any one of claims 1 to 8.