JP2015086757A - Piston device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove deposits attached on a top land part of a piston of an internal combustion engine.SOLUTION: A piston device includes a piston 12 inserted into a cylinder of the internal combustion engine in a reciprocative manner, and having a top ring groove 14 formed in a land part, and a top ring 17 fitted into the top ring groove 14 in a vertically movable manner. In an outer periphery region on the upper wall face of the top ring, a protruded part 30 is provided. The height of the protruded part 30 is set to be such a height that the upper end of the protruded part does not go beyond an upper end 20A of a top land part 20 when the top ring is moved upward in the top ring groove.

Description

  The present invention relates to a piston device for an internal combustion engine including a piston ring.

  Patent Document 1 discloses a piston device for an internal combustion engine. In addition to the piston ring, this piston device is provided with a mountain-shaped ring having a substantially cross-sectional shape in the piston land portion. This mountain-shaped ring prevents deposits from adhering or accumulating on the piston land part below (in the direction toward the bottom dead center) the mountain-shaped ring.

JP 2006-112360 A JP 2007-040470 A JP 2013-530340 A

  However, in the piston device described in Patent Document 1, deposits attached to the piston land portion (that is, the top land portion) above the mountain ring (in the direction toward the top dead center) cannot be removed. As a result, there is a risk of causing an increase in oil consumption. This is because deposits adhering to the piston land portion scrape up the oil film present on the cylinder liner surface.

  Accordingly, an object of the present invention is to remove deposits adhering to the top land portion of the piston and reduce the oil consumption of the internal combustion engine to which the piston device is applied.

  The present invention includes a piston in which a top ring groove is formed in a land portion so as to be reciprocally movable in a cylinder of an internal combustion engine, and a top ring that is fitted in the top ring groove so as to be vertically movable. , Including a piston device. And the top ring has a convex part in a region exposed on the gap between the top land part and the cylinder wall surface on the upper wall surface of the top ring, and the height of the convex part is Even when the top ring reaches the uppermost portion within the movable range in the top ring groove, the upper end of the convex portion is set to a height that does not exceed the upper end of the top land portion. Note that the vertical direction is a direction parallel to the cylinder center axis. The upper wall surface is a wall surface facing upward. The upper end is the upper end.

  According to the present invention, when the top ring moves upward in the top ring groove during engine operation, the deposit adhered to the top land portion is scraped upward by the convex portion formed on the upper wall surface of the top ring. Removed. For this reason, the oil consumption of the internal combustion engine is reduced.

  Furthermore, in the present invention, the height of the convex portion is set to a height at which the upper end of the convex portion does not exceed the upper end of the top land portion when the top ring moves upward in the top ring groove. For this reason, when the convex part moves upward, the upper end of the convex part does not enter the combustion chamber or interfere with the cylinder head.

FIG. 1 is a partial cross-sectional view of a piston device according to an embodiment of the present invention. FIG. 2A is a perspective view of the top ring of the piston device according to the embodiment of the present invention, and FIG. 2B is a side view of the top ring. FIG. 3 is an enlarged partial cross-sectional view of the piston device according to the embodiment of the present invention. FIG. 4A is a view showing the movement of the top ring in the exhaust stroke, and FIG. 4B is a view showing the movement of the top ring in the intake stroke. FIG. 5 is a view showing the top ring during wear.

<First Embodiment>
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view taken along a plane including the central axis of the piston of the piston device of the present invention. In FIG. 1, an arrow A indicates a direction toward the top dead center (hereinafter referred to as “upward”), and an arrow B indicates a direction toward the bottom dead center (hereinafter referred to as “downward”). The piston device according to the present invention is a piston device of an internal combustion engine.

<Configuration of piston device>
The piston device of this embodiment generally includes a piston 12, a top ring 17, a second ring 18, and an oil ring 19.

<Piston configuration>
The piston 12 is a substantially cylindrical member. A top ring groove 14, a second ring groove 15, and an oil ring groove 16 are formed in the land portion (that is, the outer peripheral portion) of the piston 12. Each of these three grooves 14, 15 and 16 is an annular groove having a central axis (not shown) of the piston 12 as a central axis. The top ring groove 14 is positioned closest to the piston top surface 13, and a top ring 17 is fitted in the groove 14 so as to be movable in the vertical direction. The top ring 17 is an annular member. The second ring groove 15 is located below the top ring groove 14, and a second ring 18 is fitted into the groove 15 so as to be movable in the vertical direction. The second ring 18 is an annular member. The oil ring groove 16 is positioned below the second ring groove 15, and an oil ring 19 is fitted in the groove 15 so as to be movable in the vertical direction. The oil ring 19 is an annular member.

  The piston 12 has a top land portion 20, a second land portion 21, and a third land portion 22 in its land portion. The top land portion 20 is located between the piston top surface 13 and the top ring groove 14. The second land portion 21 is located between the top ring groove 14 and the second ring groove 15. The third land portion 22 is located between the second ring groove 15 and the oil ring groove 16.

  The piston 12 is inserted into the cylinder so as to be able to reciprocate in a state where the piston 12 includes the top ring 17, the second ring 18, and the oil ring 19. The cylinder is formed by a cylinder liner 10. Therefore, the inner peripheral wall surface of the cylinder liner 10 is the cylinder wall surface. When the piston 12 is thus inserted into the cylinder liner 10, the first gas chamber 26 is defined by the top ring 17, the second ring 18, the second land portion 21, and the cylinder liner 10. A second gas chamber 27 is defined by the second ring 18, the oil ring 19, the third land portion 22, and the cylinder liner 10. The combustion chamber 25 is a space defined by the cylinder head 24, the cylinder liner 10, and the piston 12.

<Configuration of convex portion>
The convex portion 30 is provided on the upper wall surface of the top ring 17 and in the outer peripheral region of the top ring 17. Next, the detail of the convex part 30 is demonstrated with reference to FIG. FIG. 2A is a perspective view showing the periphery of the top ring abutment 17F, and FIG. 2B is a top ring abutment when the top ring is viewed from the outside to the inside of the top ring. It is the side view which showed 17F periphery.

  The top wall 17A of the top ring is an annular wall surface facing upward when the top ring 17 is fitted in the top ring groove 14 (hereinafter referred to as “fitted state”). The lower wall surface 17B of the top ring is an annular wall surface facing downward in the fitted state. The outer peripheral wall surface 17C of the top ring is a cylindrical wall surface facing outward in the piston radial direction in the fitted state. The inner peripheral wall surface 17D of the top ring is a cylindrical wall surface facing inward in the piston radial direction in the fitted state. The top ring abutment 17F is a notch formed by cutting a part of the top ring 17 along a plane including the top ring central axis along the radial direction of the top ring. The end surface 17E of the top ring is a flat wall surface formed when the abutment 17F is formed, and is a wall surface extending along a plane including the top ring central axis. That is, the abutment 17F is defined by the end surface 17E of the top ring. The outer peripheral region 17G of the top ring is an annular region located radially outward in the region of the upper wall surface 17A, and is a gap between the top land portion 20 and the wall surface of the cylinder liner 10 in the fitted state. This is the exposed area.

  As described above, the convex portion 30 is provided in the outer peripheral region 17G of the upper wall surface 17A of the top ring. And the convex part 30 has 30 A of end surfaces, the upper wall surface 30B, the outer peripheral wall surface 30C, and inner peripheral wall surface 30D.

  The end surface 30A of the convex portion is a flat wall surface extending upward from the upper wall surface 17A of the top ring, and is a wall surface flush with the end surface 17E of the top ring. Therefore, the end face 30A extends on a plane including the top ring central axis. The end face 30A has a rectangular shape having a length Lp along the top ring radial direction and a height Hp along the top ring vertical direction (that is, a direction perpendicular to the plane including the top wall surface 17A of the top ring). Have Details of the length Lp and the height Hp will be described later.

  The upper wall surface 30B of the convex portion is a flat wall surface extending from the upper end 30E of the end surface 30A to the upper wall surface 17A of the top ring. Therefore, the upper wall surface 30B is a plane inclined with respect to the upper wall surface 17A of the top ring. The width of the upper wall surface 30B along the top ring radial direction is equal to the length Lp of the end surface 30A.

  The outer peripheral wall surface 30C of the convex portion is a partially cylindrical wall surface extending on the cylindrical surface centering on the center axis of the top ring, and the upper wall surface 17A of the top ring, the end surface 30A of the convex portion, and the upper surface of the convex portion It is a wall surface extended between the wall surfaces 30B. Therefore, the outer peripheral wall surface 30C is a wall surface flush with the outer peripheral wall surface 17C of the top ring, and is a wall surface extending upward from the upper wall surface 17A of the top ring.

  The inner peripheral wall surface 30D of the convex portion is a partially cylindrical wall surface extending on the cylindrical surface centering on the top ring central axis, and the upper wall surface 17A of the top ring, the end surface 30A of the convex portion, and the convex portion The wall surface extends between the upper wall surface 30B. Therefore, the inner peripheral wall surface 30D is a wall surface extending upward from the upper wall surface 17A of the top ring.

<Dimensional requirements for protrusions>
The dimensional requirements for the convex portions will be described with reference to FIG. In the following description, the thickness Tt of the top ring 17 is the thickness of the top ring along the top ring central axis. The width Wt of the top ring groove 14 is a distance between the upper wall surface 14A and the lower wall surface 14B of the top ring groove. The height Ht of the top land portion 20 is the distance between the upper wall surface 14A of the top ring groove and the upper end 20A (piston top surface 13) of the top land portion (that is, the length of the top land portion 20 in the vertical direction). It is.

  The length Lp of the convex portion 30 is the distance of the piston clearance when the temperature of the piston 12 becomes the highest during engine operation (that is, when the piston device is applied to the internal combustion engine, during operation of the internal combustion engine). The length is set to be shorter than Dc (that is, the distance between the top land portion 20 of the piston 12 and the inner peripheral wall surface of the cylinder liner 10) (Lp <Dc).

  The height Hp of the convex portion 30 is set such that the total Hp + Tt of the height Hp and the thickness Tt of the top ring 17 is larger than the width Wt of the top ring groove 14 (Hp + Tt> Wt). The height Hp of the convex portion 30 is set to a height equal to or lower than the height Ht of the top land portion 20 (Hp ≦ Ht). The thickness Tt of the top ring 17 is set to a length shorter than the width of the top ring groove 14 (Tt <Wt).

  Therefore, when the lower wall surface 17B of the top ring is in contact with the lower wall surface 14B of the top ring groove, at least the upper part of the convex portion 30 is located between the top land portion 20 and the inner peripheral wall surface of the cylinder liner 10. When the top wall 17A of the top ring is in contact with the top wall 14A of the top ring groove, the entire convex portion 30 is located between the top land portion 20 and the inner peripheral wall surface of the cylinder liner 10.

<Effect 1 of this embodiment>
According to the piston device of the present embodiment, the following effects can be obtained. That is, as shown in FIG. 4A, in the exhaust stroke during engine operation, the piston 12 moves in the cylinder liner 10 upward (in the direction of arrow A). At this time, although the combustion gas is discharged from the combustion chamber 25 to the exhaust port (not shown), the volume of the combustion chamber 25 rapidly decreases, so the in-cylinder pressure (that is, the pressure in the combustion chamber 25) P1 is It becomes higher than the second land pressure (that is, the pressure of the first gas chamber 26) P2 (P1> P2). Accordingly, the top ring 17 is pressed against the lower wall surface 14 </ b> B of the top ring groove 14.

  On the other hand, as shown in FIG. 4B, in the intake stroke following the exhaust stroke, the piston 12 moves in the cylinder liner 10 downward (in the direction of arrow B). At this time, although air is sucked into the combustion chamber 25 through an intake port (not shown), the volume of the combustion chamber 25 increases rapidly, so the in-cylinder pressure P1 becomes lower than the second land pressure P2. (P1 <P2). Accordingly, the top ring 17 is pressed against the upper wall surface 14 </ b> A of the top ring groove 14.

  That is, when the engine stroke is shifted from the exhaust stroke to the intake stroke, the top ring 17 moves upward in the top ring groove 14. At this time, at least a part 45 </ b> A of the deposit 45 with the convex portion 30 adhering to the top land portion 20 is scraped upward (in the direction of arrow A), and the scraped deposit 45 </ b> A is discharged into the combustion chamber 25. Is done. That is, the deposit attached to the top land portion 20 is removed by the convex portion 30. As a result, the deposit attached to the top land portion 20 does not scrape the oil film on the cylinder liner 10. Therefore, according to this embodiment, the effect that the oil consumption of an internal combustion engine can be reduced is acquired.

  In the present embodiment, the deposit is removed by the convex portion 30 provided on the top ring 17, so that the number of parts of the piston device does not increase and the rigidity of the piston does not decrease.

  Furthermore, in this embodiment, the convex part 30 is provided only in one place of the upper wall surface 17A of the top ring. That is, the convex part 30 is provided only in a part of the entire circumference of the upper wall surface 17A of the top ring. However, the convex part 30 can remove deposits over the entire circumference of the top land part 20.

  That is, there is a piston clearance between the outer peripheral wall surface of the piston 12 and the inner peripheral wall surface of the cylinder liner 10. For this reason, the piston 12 performs a swing motion during the reciprocating motion. Therefore, a state occurs in which the central axis of the piston 12 is inclined with respect to the central axis of the cylinder liner 10. At this time, the top ring 17 receives a circumferential force from the cylinder liner 10. For this reason, the top ring 17 rotates in the circumferential direction of the piston 12. Therefore, even if the convex part 30 is provided only in one place of the top ring 17, the convex part 30 can remove a deposit over the perimeter of the top land part 20. FIG.

<Effect 2 of this embodiment>
Furthermore, in the present embodiment, the height Hp of the convex portion 30 is set to a height equal to or lower than the height Ht of the top land portion 20 (Hp ≦ Ht). For this reason, even when the upper wall surface 17A of the top ring is in contact with the upper wall surface 14A of the top ring groove, the upper end 30E of the convex portion exceeds the upper end 20A of the top land portion (that is, the piston top surface 13). Thus, it does not protrude into the combustion chamber 25. For this reason, when the convex part 30 moves upward, the upper end 30E of the convex part does not enter the combustion chamber 25 nor interfere with the cylinder head 24.

<Effect 3 of this embodiment>
Furthermore, in the present embodiment, the height Hp of the convex portion 30 is set to a height at which the total Hp + Tt of the height Hp and the thickness Tt of the top ring 17 is larger than the width Wt of the top ring groove 14. (Hp + Tt> Wt). For this reason, even when the top ring 17 moves radially inward when the top ring 17 is in contact with the lower wall surface 14 </ b> B of the top ring groove, the convex portion 30 enters the top ring groove 14. No so-called stick phenomenon.

<Effect 4 of this embodiment>
In addition, since the temperature of the piston 12 is higher than the temperature of the cylinder liner 10 during engine operation, the thermal expansion of the piston 12 is larger than the thermal expansion of the cylinder liner 10. Therefore, the piston clearance distance Dc during engine operation is shorter than the piston clearance distance Dc during engine stop. For example, when the piston 12 is made of an aluminum alloy and the cylinder liner 10 is made of cast iron, the thermal expansion of the piston 12 is even greater than the thermal expansion of the cylinder liner 10. For this reason, the distance Dc of the piston clearance during engine operation is further shorter than the distance Dc of the piston clearance during engine stop. Here, even if the length Lp of the convex portion 30 is set to be shorter than the distance Dc of the piston clearance when the engine is stopped, the temperature of the piston 12 becomes the highest during the engine operation. If the piston clearance is equal to or longer than the distance Dc of the piston clearance, the projecting portion 30 is sandwiched between the piston 12 and the cylinder liner 10 during engine operation, and the top ring 17 moves in the top ring groove 14. Will not be able to.

  However, in the present embodiment, the length Lp of the convex portion 30 is set to be shorter than the distance Dc of the piston clearance when the temperature of the piston 12 becomes the highest during engine operation. Therefore, the top ring 17 can reliably move in the top ring groove 14 during engine operation.

<Additional configuration 1 of this embodiment>
By the way, the top ring 17 repeatedly collides with the lower wall surface 14 </ b> B of the top ring groove by the reciprocating motion of the piston 12. Therefore, depending on the material constituting the top ring 17, as shown in FIG. 5, a portion of the top ring 17 that collides with the lower wall surface 14 </ b> B (hereinafter referred to as a “lower part”) is worn, and the top ring The initial lower wall surface 17B may be retracted to the position indicated by reference numeral 17B ′. Thus, if the lower portion of the top ring 17 is worn, the stick phenomenon may occur when the top ring 17 moves downward in the top ring groove 14.

  Therefore, in the above-described embodiment, even if the lower portion of the top ring 17 is worn, the top ring is calculated from the sum Hp + Tt of the height Hp of the convex portion 30 and the thickness Tt of the top ring 17 in order to avoid the stick phenomenon. The value obtained by subtracting the maximum wear width Wal of the lower portion 17 (that is, the distance from the initial lower wall surface 17B of the top ring to the lower wall surface 17B ′ after wear) measured along the center axis of the top ring is the top ring groove 14 The height Hp of the convex portion 30 may be set so as to be larger than the width Wt (Hp + Tt−Wal> Wt). The maximum wear width is a wear width assumed from the service life of a product to which the piston device is applied.

<Additional configuration 2 of this embodiment>
Similarly, the top ring 17 repeatedly collides with the upper wall surface 14 </ b> A of the top ring groove by the reciprocating motion of the piston 12. For this reason, depending on the material constituting the top ring 17, as shown in FIG. 5, the portion of the top ring 17 that collides with the upper wall surface 14A (hereinafter referred to as the “upper portion”) wears out. The initial upper wall surface 17A may be retracted to the position indicated by reference numeral 17A ′. Thus, if the upper part of the top ring 17 is worn, when the top ring 17 moves upward in the top ring groove 14, the upper end 30E of the convex portion may protrude beyond the upper end 20A of the top land portion. There is.

  Therefore, in the above-described embodiment, even if the upper portion of the top ring 17 is worn, the top land portion 20 is not high so that the upper end 30E of the convex portion 30 does not protrude beyond the upper end 20A of the top land portion. A value obtained by subtracting the maximum wear width Wau of the upper portion of the top ring 17 from the height Ht (that is, the distance from the initial upper wall surface 17A of the top ring measured along the central axis of the top ring to the upper wall surface 17A ′ after wear) You may make it set the height Hp of the convex part 30 to the following values (Hp + Wau <= Ht).

<Scope of application of the present invention>
The shape of the convex portion is not limited to the shape described above, and is at least a shape satisfying the dimensional condition of the convex portion described in the description of the embodiment (excluding the dimensional condition of the convex portion described in the additional configuration). Any shape may be used as long as the deposit can be scraped upward and removed.

  In the above-described embodiment, the convex portion is the outer peripheral region of the upper wall surface of the top ring and is provided adjacent to the joint of the top ring, but may be provided in the outer peripheral region of the upper wall surface of the top ring. For example, it is not necessary to be provided adjacent to the joint of the top ring.

  In the embodiment described above, the convex portion is provided at only one location on the outer peripheral region of the upper wall surface of the top ring, but the convex portion may be provided on the entire outer periphery region of the upper wall surface of the top ring. However, it may be provided at a plurality of locations in the outer peripheral region of the upper wall surface of the top ring.

<Summary of Embodiment>
The piston device of the internal combustion engine according to the embodiment described above can be broadly understood. The piston device is reciprocally inserted into a cylinder (cylinder formed by the cylinder liner 10) of the internal combustion engine, and the top ring groove 14 is formed in the land portion. In the piston device including the formed piston 12 and the top ring 17 fitted in the top ring groove 14 so as to be movable in the vertical direction, the top ring 17 is an upper wall surface 17A of the top ring. A convex portion 30 is provided in a region exposed to the gap between the top land portion 20 and the wall surface of the cylinder liner 10, and the height Hp of the convex portion 30 is determined by the top ring 17 being the top ring. Even when the uppermost portion within the movable range in the groove 14 is reached, the upper end 30E of the convex portion 30 is the upper end 2 of the topland portion. Is set at a height not exceeding A (piston top face 13), said to be a piston device.

  DESCRIPTION OF SYMBOLS 10 ... Cylinder liner, 12 ... Piston, 14 ... Top ring groove, 17 ... Top ring, 18 ... Second ring, 20 ... Top land part, 21 ... Second land part, 30 ... Convex part

Claims (1)

A piston that is reciprocally inserted into a cylinder of the internal combustion engine and has a top ring groove formed in a land portion;
A top ring fitted in the top ring groove so as to be movable in the vertical direction;
In a piston device comprising:
The top ring has a convex portion in an upper wall surface of the top ring and exposed in a gap between the top land portion and the cylinder wall surface, and the height of the convex portion is Even when the top ring reaches the uppermost portion within the movable range in the top ring groove, the upper end of the convex portion is set to a height that does not exceed the upper end of the top land portion.
Piston device.

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