JP2010229858A - Piston, piston ring, and reciprocating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston capable of suppressing a lubricant from being discharged from a ring groove by a simple structure, a piston ring, and a reciprocating device equipped with at least either of the piston or the piston ring, and reducing the amount of the consumption of the lubricant. <P>SOLUTION: In the piston 10, three ring grooves 50 opened to an outer peripheral side and to which the piston rings 30, 32, 33 are independently installed, and an oil collecting groove 52 opened to a part on a crown face 10A side in each ring groove 50 are formed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a piston, a piston ring, and a reciprocating device.

  A wedge-shaped annular groove-like space is formed in the land just above the oil ring and the land just below the top ring to prevent sudden pressure fluctuations and oil pressure fluctuations in the land space just above the oil ring groove in the piston for an internal combustion engine. A technique for obtaining an oil blowing effect by gas is known (for example, see Patent Document 1). Further, a piston ring structure including an outer ring that is in sliding contact with the inner wall surface of the cylinder and an inner ring that is in contact with the bottom wall surface of the ring groove of the piston is known (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 6-249062 JP 2007-92985 A

  However, the technique described in Patent Document 1 does not consider the lubricating liquid in the ring groove. In the technique described in Patent Document 2, the structure of the piston ring structure is complicated, and there is a problem that oil flowing downward from the combustion chamber side is also sealed by the piston ring structure.

  In view of the above facts, an object of the present invention is to obtain a piston and a piston ring that can suppress the discharge of the lubricating liquid from the ring groove to the crown surface side with a simple structure. Another object of the present invention is to provide a reciprocating device that includes at least one of the above-described piston and piston ring and can reduce the consumption of the lubricating liquid.

  The piston according to the first aspect of the present invention opens to the outer peripheral side, a ring groove for mounting the piston ring, and a concave portion opened to allow the lubricating liquid to enter and exit at a crown side portion of the ring groove, Is formed.

  In the piston according to the first aspect, the acceleration in the reciprocating direction acts on the lubricant in the ring groove by the acceleration (inertia) accompanying the reciprocating motion. When the acceleration in the direction of moving the lubricating liquid toward the crown surface acts, the lubricating liquid enters the concave portion of the piston and is temporarily stored (held) in the concave portion. For this reason, in this piston, it is effective that the lubricating liquid is discharged to the crown surface side (high pressure side) from the gap with the piston ring when the acceleration in the direction of moving the lubricant liquid to the crown surface side acts. It is suppressed.

  Thus, in the piston according to the first aspect, the lubricating liquid can be prevented from being discharged from the ring groove toward the crown surface with a simple structure.

  A piston according to a second aspect of the present invention is the piston according to the first aspect, wherein the recess has an annular shape extending over the entire length of the ring groove.

  In the piston according to the second aspect, since the concave portion forms an annular shape over the entire circumference, a sufficient amount of lubricating liquid can be temporarily stored in the concave portion having a small cross section. In addition, the processing of the recesses is easier than the configuration in which the recesses are intermittently formed.

  A piston according to a third aspect of the present invention is the piston according to the first or second aspect, wherein the concave portion has a cross-sectional shape that opens at a groove bottom of the ring groove and extends from the opening toward the crown surface. Have.

  In the piston according to claim 3, since the groove bottom portion in which the lubricating liquid in the ring groove is easily moved in the piston reciprocating direction and the recess extending in the depth direction toward the crown surface side is opened, The lubricating liquid tends to advance and retreat with respect to the concave portion due to the acceleration in the direction.

  The piston according to a fourth aspect of the present invention is the piston according to any one of the first to third aspects, wherein the concave portion faces the opposite side of the crown surface with respect to the groove bottom of the ring groove. Open.

  In the piston according to claim 4, since the concave portion opens in the groove wall on the crown surface side toward the side opposite to the crown surface side (the anti-coron surface side), the depth direction is the piston reciprocating direction (acceleration direction). ), And the lubricating liquid is more likely to advance and retreat with respect to the recess due to acceleration in the reciprocating direction of the piston.

  The piston according to a fifth aspect of the present invention is the piston according to any one of the first to third aspects, wherein the concave portion opens toward the outer peripheral side at the groove bottom of the ring groove, and the opening And a cross-sectional shape extending obliquely inward in the radial direction on the crown surface side from the portion.

  In the piston according to claim 5, the concave portion opens toward the outer peripheral side at the groove bottom, and the concave portion has a deep configuration extending obliquely toward the crown surface side and the inner diameter side. The lubricant advances and retreats with respect to the concave portion due to the acceleration.

  A piston ring according to a sixth aspect of the present invention is a piston ring mounted on the piston according to the fifth aspect, wherein the piston ring is opened on the inner peripheral surface so as to face the concave portion, and is on the crown surface side and has a diameter. A recess extending obliquely outward in the direction is provided.

  In the piston ring according to the sixth aspect, the lubricating liquid advances and retreats with respect to the concave portion by the acceleration (inertia) accompanying the reciprocating motion of the piston. For this reason, for example, even when the holding capacity of the lubricating liquid by the concave portion of the piston according to claim 5 is inferior, a sufficient amount of lubricating liquid can be temporarily stored with the concave portion of the piston.

  Thus, in the piston ring according to the sixth aspect, the lubricating liquid can be prevented from being discharged from the ring groove toward the crown surface with a simple structure.

  A piston ring according to a seventh aspect of the present invention is provided with a recess that is opened on the inner peripheral surface so as to face the ring groove of the piston and that extends obliquely outward in the radial direction on the crown surface side of the piston. ing.

  In the piston ring according to claim 7, when the acceleration toward the crown surface acts on the lubricating liquid in the ring groove of the piston due to the acceleration (inertia) accompanying the reciprocating motion of the piston, the lubricating liquid is placed in the recess. Get in. That is, in this piston ring, when an acceleration in the direction of moving the lubricating liquid toward the crown surface acts, the lubricating liquid is temporarily stored (held) in the concave portion, and the lubricating liquid is stored on the crown surface side of the piston ( Emission to the high pressure side is effectively suppressed.

  Thus, in the piston ring according to the seventh aspect, the lubricating liquid can be prevented from being discharged from the ring groove toward the crown surface with a simple structure.

  The reciprocating device according to the invention described in claim 8 is provided in a cylinder, in the piston according to any one of claims 1 to 5 provided in the cylinder so as to be capable of reciprocating, and in the ring groove of the piston. And a piston ring that seals between the cylinder and the piston in a lubricated state.

  In the reciprocating motion according to the eighth aspect, the space between the cylinder inner peripheral surface and the piston outer peripheral surface is sealed in a lubricated state by the piston ring. When acceleration toward the piston crown surface is applied to the lubricant due to the reciprocating motion of the piston with respect to the cylinder, and the piston ring does not follow the movement of the lubricant, the groove wall on the crown surface side in the ring groove and the piston ring A gap is formed between the two. Here, in this reciprocating device, since the concave portion is formed in the piston, the lubricating liquid on which the acceleration toward the piston crown surface side is temporarily held in the concave portion, and the groove wall on the crown surface side in the ring groove And the piston ring and the gap are effectively prevented from being discharged from the gap.

  Thus, in the reciprocating device according to the eighth aspect, the piston is provided, and the consumption amount of the lubricating liquid can be reduced. Examples of the reciprocating device in the present invention include an internal combustion engine, an external combustion engine, and a reciprocating compressor.

  A reciprocating device according to a ninth aspect of the present invention is a cylinder, a piston according to the fifth aspect of the present invention provided in a reciprocable manner in the cylinder, and a ring groove of the piston. The piston ring according to claim 6 or 7, wherein the gap is sealed in a lubricated state.

  In the reciprocating motion according to the ninth aspect, the space between the cylinder inner peripheral surface and the piston outer peripheral surface is sealed in a lubricated state by the piston ring. When acceleration toward the piston crown surface is applied to the lubricant due to the reciprocating motion of the piston with respect to the cylinder, and the piston ring does not follow the movement of the lubricant, the groove wall on the crown surface side in the ring groove and the piston ring A gap is formed between the two. Here, in this reciprocating device, since the recess is formed in each of the ring groove of the piston and the inner peripheral surface of the piston ring, the lubricating liquid acted by the acceleration toward the piston crown side temporarily enters into these recesses. And is effectively prevented from being discharged to the crown surface side through the gap between the groove surface and the piston ring on the crown surface side in the ring groove.

  Thus, in the reciprocating device according to the ninth aspect, the piston and the piston ring are provided, and the consumption amount of the lubricating liquid can be reduced. Examples of the reciprocating device in the present invention include an internal combustion engine, an external combustion engine, and a reciprocating compressor.

  As described above, the piston and the piston ring according to the present invention have an excellent effect that the lubricating liquid can be suppressed from being discharged from the ring groove to the crown surface side with a simple structure.

  In addition, the reciprocating device according to the present invention includes at least one of the piston and the piston ring, and has an excellent effect that the consumption amount of the lubricating liquid can be reduced.

It is sectional drawing which expands and shows the principal part of the piston which comprises the engine which concerns on the 1st Embodiment of this invention. Each of (A) to (E) is an enlarged cross-sectional view of a main part showing an example of the shape of an oil sump groove formed in the piston according to the first embodiment of the present invention. 1 is a schematic cross-sectional view of an engine to which a piston according to a first embodiment of the present invention is applied. It is a figure which shows typically a movement of the lubricating oil in a ring groove | channel by piston inertia force, Comprising: (A) is a lubricating oil to the oil sump groove at the time of using the piston which concerns on the 1st Embodiment of this invention. Sectional drawing which shows the collection condition of this, (B) is sectional drawing which shows the lubricating oil discharge | emission condition to the land part at the time of using the piston which concerns on a comparative example. It is a figure for demonstrating operation | movement of each part accompanying the action | operation of an engine, (A) is a diagram which shows the acceleration of a piston, (B) is a diagram which shows the position of the axial direction in the ring groove of a top ring, (C) is a diagram showing an axial position in the ring groove of the second ring, and (D) is a diagram showing an axial position in the ring groove of the oil ring. It is sectional drawing which expands and shows the principal part of the piston which comprises the engine which concerns on the 2nd Embodiment of this invention. It is sectional drawing about the collection condition of the lubricating oil to the oil sump groove | channel of the piston and piston ring which concern on the 2nd Embodiment of this invention.

  An engine 11 which is an internal combustion engine as a piston 10 and a reciprocating device according to a first embodiment of the present invention will be described with reference to FIGS. First, the schematic overall configuration of the engine 11 will be described, and then the piston 10 will be described.

(Schematic overall configuration of the engine)
FIG. 3 shows a cross-sectional view along a plane orthogonal to the axis of the crankshaft 12 in the engine 11. As shown in this figure, the engine 11 includes a cylinder block 14, an oil pan 16 joined to the lower part of the cylinder block 14, a cylinder head 18 joined to the upper part of the cylinder block 14, and an upper part of the cylinder head 18. The cylinder head cover 20 is joined.

  The lower part of the cylinder block 14 and the oil pan 16 constitute a crankcase 24 in which a crank chamber 22 in which the crankshaft 12 is accommodated is formed. The crankshaft 12 of the engine 11 is connected to a piston 10 disposed in a cylinder 28 of the cylinder block 14 so as to be displaceable in the axial direction of the cylinder 28 via a connecting rod 26.

  The piston 10, the cylinder 28 of the cylinder block 14, and the cylinder head 18 form a combustion chamber C in which fuel is combusted. A cooling water passage 14 </ b> A for circulating engine cooling water is formed on the side of the cylinder 28 in the cylinder block 14.

  The inner surface of the cylinder 28 of the cylinder block 14 and the piston 10 are sealed with piston rings 30, 32, and 33. In this embodiment, the piston ring 30 is a compression ring top ring, the piston ring 32 is a compression ring second ring, and the piston ring 33 is an oil control ring (also referred to as an oil ring).

  The cylinder head 18 is provided with an intake port 34 for introducing a mixture of gasoline and air into the cylinder 28 and an exhaust port 36 for discharging combustion exhaust gas (exhaust gas) from the cylinder 28. The intake port 34 is opened and closed by an intake valve 38 at a portion communicating with the cylinder 28. The intake valve 38 is driven by an intake cam 44 of a valve operating system 42 through a valve stem 38A protruding into a cylinder head chamber 40 formed by the cylinder head 18 and the cylinder head cover 20.

  Similarly, the exhaust port 36 is configured to be opened and closed by an exhaust valve 46 at a portion communicating with the cylinder 28. The exhaust valve 46 is driven by an exhaust cam 48 of the valve operating system 42 via a valve stem 46A protruding into the cylinder head chamber 40. The intake cam 44 and the exhaust cam 48 are rotated in synchronization with the driving force of the crankshaft 12 transmitted via a timing sprocket, a timing chain, etc. (not shown).

  In this engine 11, the lubricating oil L as the lubricating liquid in the oil pan 16 is supplied to the crankshaft 12, the piston 10, the connecting rod 26, and the valve train 42 by an oil pump (not shown) so that each sliding portion is It is designed to be lubricated. Lubricating oil used for lubricating each sliding portion (lubricated portion) is returned to the oil pan 16 by gravity or the like.

  In this embodiment, the engine 11 is a row type engine in which a plurality of cylinders 28 are formed in a cylinder block 14.

(Piston configuration)
In FIG. 1, the main part of the piston 10 is shown in a schematic sectional view. As shown in this figure, the piston 10 has a substantially bottomed cylindrical shape with the crown surface 10A as the bottom, and three ring grooves 50 are formed in an annular shape over the entire circumference in the cylindrical portion 10B. Yes. As described above, the piston groove 30 that is the top ring of the compression ring is attached to the ring groove 50 that is disposed closest to the crown surface 10A. A ring groove 50 that is disposed farthest from the crown surface 10A is fitted with a piston ring 33 that is an oil ring. The ring groove 50 arranged in the middle of these is fitted with a piston ring 32 which is a second ring of the compression ring.

  The piston 10 is formed with an oil reservoir groove 52 that is a liquid reservoir groove as a recess communicating with each ring groove 50. The oil sump groove 52 is opened on the crown surface 10A side from the center portion in the groove width direction on the groove bottom 50A side of the corresponding ring groove 50, and extends from the opening portion to the crown surface 10A side (the crown surface 10A side is extended). It has a cross-sectional shape. As such an oil sump groove 52, the shape illustrated in FIGS. 2 (A) to 2 (E) can be employed. Hereinafter, these will be supplemented.

  The oil sump groove 52A shown in FIG. 2A is formed in the vicinity of the corner between the groove bottom 50A of the ring groove 50 and the groove wall 50B on the crown surface 10A side, and faces the groove wall 50C facing the groove wall 50B. Are open. That is, the oil sump groove 52A is opened toward the groove wall 50C in the groove wall 50B in a cross-sectional view perpendicular to the circumferential direction, and extends from the opening to the crown surface 10A side substantially along the axial direction of the piston 10 (axis line). The direction is almost coincident with the depth direction). The groove bottom of the oil sump groove 52A is rounded.

  The oil sump groove 52B shown in FIG. 2 (B) is configured in the same manner as the oil sump groove 52A described above except that the groove bottom is flat. The oil sump groove 52C shown in FIG. 2 (C) is common to the oil sump grooves 52A and 52B described above in the arrangement, the opening direction, and the depth direction, and the groove width narrows toward the groove bottom in a cross-sectional view perpendicular to the circumferential direction. They differ from these in that they form a wedge shape (triangular shape). The oil reservoir groove 52C has an inner circumferential groove wall that is a cylindrical surface along the groove bottom 50A, and an outer circumferential groove wall that is a conical surface.

  The oil sump groove 52D shown in FIG. 2 (D) mainly opens toward the outer peripheral side (radially outer side) at the groove bottom 50A, and faces the crown surface 10A side and radially inward from the opening. It extends diagonally (has a deep structure in the diagonal direction). In this example, the groove bottom of the oil sump groove 52D is located closer to the crown surface 10A than the groove wall 50B. Various shapes such as the oil sump grooves 52A to 52C can be adopted for the groove bottom of the oil sump groove 52D. Further, in this example, the oil sump groove 52D is opened across a part of the groove wall 50B, but may be opened only at the groove bottom 50A (a part including the part on the crown surface 10A side). good. Further, in this example, a part of the groove bottom 50A on the anti-crown surface 10A side is left as a cylindrical surface similar to the example of FIGS. 2 (A) to 2 (C).

  In the oil sump groove 52E shown in FIG. 2E, the groove depth direction substantially coincides with the groove depth direction of the oil sump groove 52D described above, and only the groove bottom 50A (including the portion on the crown surface 10A side). Is different from the oil sump groove 52D in that the position of the groove bottom in the axial direction of the piston 10 is approximately the same as that of the groove wall 50B. Further, in this example, a part of the groove bottom 50A on the side of the anti-crown surface 10A is left as a cylindrical surface similar to the example of FIGS.

  In FIG. 1, the oil sump groove 52 </ b> A is illustrated as the oil sump groove 52, but the oil sump grooves 52 </ b> A to 52 </ b> E described above can be applied as appropriate. Further, a different oil sump groove 52 may be applied to a part of the three ring grooves 50, and a different oil sump groove 52 may be applied to each ring groove 50.

  Each ring groove 50 of the piston 10 has a slightly larger groove width (opening width along the axial direction) than the thickness of the piston rings 30, 32, 33 to be mounted. Thereby, the sliding friction between the groove wall 50B or the groove wall 50C of the ring groove 50 and the piston rings 30, 32, 33 is reduced, and the followability of the piston rings 30, 32, 33 to the inner surface (bore) of the cylinder 28 is improved. It is secured. On the other hand, the piston rings 30, 32, 33 are allowed to be displaced relative to the piston 10 in the axial direction within the ring groove 50.

  In the piston 10, the outer peripheral surface on the crown surface 10A side with respect to the ring groove 50 in the cylindrical portion 10B is a land portion 10C. For example, the land portion 10C on the crown surface 10A side is the top land with respect to the ring groove 50 to which the piston ring 30 is mounted, and is between the ring groove 50 to which the piston ring 32 is mounted and the ring groove 50 to which the piston ring 30 is mounted. The land portion 10C is a second land, and the land portion 10C between the ring groove 50 to which the piston ring 33 is attached and the ring groove 50 to which the piston ring 32 is attached is called a third land or the like.

  Next, the operation of the first embodiment will be described.

  In the engine 11 including the piston 10 having the above-described configuration, for example, the reciprocating linear motion of the piston 10 is the rotational motion of the crankshaft 12 by repeating the suction stroke, the compression stroke, the expansion stroke, and the exhaust stroke in this order. Is converted into power. In addition, the intake cam 44 and the exhaust cam 48 are driven to rotate by the rotation of the crankshaft 12, and the intake valve 38 and the exhaust valve 46 are driven to maintain the intake stroke, compression stroke, expansion stroke, and exhaust stroke.

  At this time, the piston rings 30, 32, 33 mounted in the corresponding ring grooves 50 of the piston 10 slide on the inner surface of the cylinder 28 under the lubrication condition with the lubricating oil L, and Seal the gap.

  During the operation of the engine 11, acceleration acts on the piston 10 as shown in FIG. The lubricating oil L in the ring groove 50 of the piston 10 has an upward inertia when the acceleration (inertial force) acting on the piston 10 is upward (in FIG. 5A, the acceleration exceeds 0 on the + side). A force acts, and the inertial force moves to the groove wall 50B side of the ring groove 50 on the crown surface 10A side. On the other hand, the piston rings 30, 32, and 34 are affected by the frictional force with the cylinder 28, the pressure difference between the surrounding gases, and the like in addition to the acceleration acting on the piston 10, and FIG. As shown in FIG. 5B to 5D, the piston rings 30, 32, and 33 are biased toward the groove wall 50B (crown surface 10A), and the lower ring position is the piston ring. 30, 32, and 33 are biased toward the groove wall 50 </ b> C (anti-crown surface 10 </ b> A).

  From FIG. 5 (A) to FIG. 5 (D), when the lubricating oil L receives the inertial force on the crown surface 10A side in 50, the piston rings 30, 32, 33 are biased toward the groove wall 50C side. Timing is known (it is understood that it exists (see the range surrounded by an imaginary line in FIGS. 5B to 5D)).

  Here, since the piston 10 is provided with the oil sump groove 52 that communicates with the ring groove 50, the lubricating oil L that has received the inertial force toward the crown surface 10A enters the oil sump groove 52 and enters the oil sump. It is temporarily stored (held or collected) in the groove 52. Thereby, in the engine 11 to which the piston 10 is applied, the lubricating oil L is suppressed from moving to the combustion chamber C side.

  For example, as shown in FIG. 4B, in the piston 100 according to the comparative example that does not have the oil sump groove 52, the lubricating oil L receives the inertial force on the crown surface 10A side within 50, while the piston rings 30, 32 are provided. , 33 is displaced to the groove wall 50C side, the lubricating oil L escapes from the ring groove 50 through the groove wall 50B and the gap G between the piston rings 30, 32, 33. Thus, the lubricating oil L that has flown out of the ring groove 50 is sealed on the anti-crown surface 10A side by the piston rings 30, 32, and 33, so that the land located on the crown surface 10A side with respect to the ring groove 50 that has slipped out. It escapes to the part 10C (refer FIG. 1).

  On the other hand, in the piston 10, as shown in FIG. 4A, at least a part of the lubricating oil L that has received an inertial force toward the crown surface 10 </ b> A in the ring groove 50 is temporarily stored in the oil sump groove 52. Retained. For this reason, it is prevented or effectively suppressed that the lubricating oil L escapes from the ring groove 50 through the gap G between the groove wall 50B and the piston rings 30, 32, 33.

  Therefore, in the piston 10, the lubricating oil L in the ring groove 50 receives an inertial force toward the crown surface 10A, and a gap G between the groove wall 50B and the piston rings 30, 32, 33 is formed (piston rings 30, 32). , 33 cannot seal the extrusion of the lubricating oil L outward in the radial direction) even if a timing occurs, the lubricating oil L is prevented or effectively prevented from escaping from the ring groove 50 to the land portion 10C side at the timing. It is suppressed.

  Moreover, in the piston 10, the above effect can be obtained with a simple structure in which the oil sump groove 52 communicating with the ring groove 50 is simply formed, thereby preventing or suppressing the slipping of the lubricating oil L to the land portion 10C. Thus, in the piston 10 according to the first embodiment, the lubricating oil L can be suppressed from being discharged from the ring groove 50 to the land portion 10C on the crown surface 10A side with a simple structure.

  For this reason, in the engine 11 to which the piston 10 is applied, the lubricating oil L that has escaped to the land portion 10C reaches the combustion chamber C and is consumed or combusted in the combustion chamber C. Is done.

  In particular, in the piston 10, since the oil reservoir groove 52 forms an annular shape over the entire circumference, a sufficient amount of the lubricating oil L can be temporarily stored in the oil reservoir groove 52 having a small cross section. Further, in the piston 10, for example, the oil reservoir groove 52 can be easily processed as compared with a configuration in which the oil reservoir groove 52 is intermittently formed in the circumferential direction.

  Furthermore, in the piston 10, the groove bottom of the oil sump groove 52 is located on the crown surface 10 </ b> A side with respect to the opening. In other words, the direction from the opening toward the crown surface 10 </ b> A is the depth direction of the oil sump groove 52. Therefore, the lubricating oil L is likely to advance and retreat with respect to the oil sump groove 52 by the inertial force acting in the axial direction. In particular, as shown in FIGS. 2A to 2C, a piston having an oil reservoir groove 52 that opens toward the groove wall 50C and extends along the axial direction (the axial direction is the depth direction). 10, the lubricating oil L is more likely to advance and retreat relative to the oil sump groove 52.

  Further, in the piston 10, the entire groove bottom 50A of the ring groove 50 (when the oil reservoir grooves 52A to 52C are employed) or a part of the anti-crown surface 10A side (when the oil reservoir grooves 52D and 52E are employed) Since the cylindrical surface is the same as in the case where the oil sump groove 52 is not provided, the assemblability of the piston rings 30, 32, and 34 is ensured. That is, in the piston 10, since the oil groove 52 is formed, the ring groove 50 is not deepened (reduced in diameter) as a whole, and the assembling property of the piston rings 30, 32, 34 is sacrificed. Without this, the discharge of the lubricating oil L to the land portion 10C can be suppressed.

  On the other hand, in the piston 10, when an inertial force toward the anti-crown surface 10 </ b> A acts on the lubricating oil L, the lubricating oil L escapes from the oil pool groove 52, and the piston rings 30, 32, 33 and the ring groove 50, cylinder 28, or returned to the oil pan 16.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. Note that components / portions that are basically the same as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted, and illustration may be omitted. FIG. 6 is an enlarged cross-sectional view of a main part corresponding to FIG. 1, showing an engine 64 configured by mounting piston rings 60 and 62 according to the second embodiment on the piston 10.

  As shown in this figure, the piston 10 constituting the engine 64 has an oil sump groove 52E formed in a ring groove 50 in which a piston ring 60 as a top ring as a compression ring and a piston ring 62 as a second ring are mounted. ing. The piston rings 60 and 62 constituting the engine 64 are formed with a liquid reservoir groove 66 which is a liquid reservoir groove as a concave portion on the inner peripheral surfaces 60A and 62A facing the groove bottom 50A.

  The liquid reservoir groove 66 is opened at a substantially central portion in the thickness direction of the inner peripheral surfaces 60A and 62A, and extends obliquely from the opening toward the crown surface 10A side and the radially outer side (the direction toward this Nana is deep). It is said that the direction. In this embodiment, the liquid pool groove 66 is required to face at least a part of the oil pool groove 52 opened at the groove bottom 50A of the ring groove 50 in a state where the piston rings 60 and 62 are mounted in the ring groove 50. It is the structure arrange | positioned.

  Further, the inner peripheral surfaces 60A, 62A of the piston rings 60, 62 are in a range where at least a part of the anti-crown surface 10A side is a cylindrical surface (the liquid collecting groove 66 is not provided). The liquid pool groove 66 is formed over substantially the entire circumference of the piston rings 60 and 62 except for a joint (circumferential end) (not shown).

  Further, in the engine 64, the ring groove 50 to which the piston ring 33, which is an oil ring that cannot form the liquid pool groove 66, is attached to any one of the oil pool grooves 52A to 52D (in the example of FIG. 6, the oil pool groove). 52D) is formed. Other configurations of the engine 64 are basically the same as the corresponding configurations of the engine 11.

  Therefore, the engine 64 according to the second embodiment can basically obtain the same effect by the same operation as that of the engine 11 according to the first embodiment. Further, the oil sump groove 52E is lower in the collection capacity (temporary holdable amount) of the lubricating oil L than the oil sump grooves 52A to 52D, but is combined with the piston rings 60 and 62 having the liquid sump groove 66. As a result, a sufficient collection ability can be obtained as a whole. That is, in the engine 64, the effect of suppressing the discharge of the lubricating oil L equivalent to the engine 11 in which any of the oil reservoir grooves 52A to 52D is formed in the ring groove 50 to the land portion 10C, and the consumption of the lubricating oil L based on the effect. An amount reduction effect can be obtained.

  Supplementing the collection of the lubricating oil L in the oil sump grooves 52E and 66, as shown in FIG. 7, the lubricating oil L directed toward the crown surface 10A side by the inertial force is only in the oil sump grooves 52E and 66 due to wettability. It enters (introduces) the oil pool grooves 52E and 66 along the wall surface.

  In the second embodiment described above, the piston rings 60 and 62 having the liquid reservoir groove 66 are combined with the piston 10 having the oil reservoir groove 52E. However, the present invention is not limited to this. For example, the piston rings 60 and 62 may be combined with the piston 10 having any of the oil sump grooves 52A to 52D, and the piston rings 60 and 62 may be combined with a piston not having the oil sump groove 52. It is also good. In other words, the piston rings 60 and 62 according to the second embodiment can independently collect the lubricating oil L without depending on the oil pool groove 52 on the piston side (the effect of suppressing the discharge of the lubricating oil L to the land portion 10C). ) Can be played.

  Further, in each of the above-described embodiments, an example in which the oil sump groove 52 is formed in each ring groove 50 has been shown. However, the present invention is not limited to this, and for example, oil is applied to only a part of the three piston rings 30. It is good also as a structure in which the accumulation groove | channel 52 was formed. Therefore, for example, the oil retaining groove 52 is formed only in the ring groove 50 for the piston ring 33 having a relatively large oil amount and the ring groove 50 for the piston ring 32 or the piston ring 62, and the piston ring 30 or the top ring. The ring groove 50 for the piston ring 60 can be configured such that the oil sump groove 52 is not formed.

  Furthermore, in each of the above-described embodiments, the example in which the oil sump grooves 52 and 66 are continuously formed in the circumferential direction is shown. However, the present invention is not limited to this, and for example, the oil sump grooves 52 and 66 are circumferential. It is good also as a structure formed intermittently in the direction.

  Further, in each of the above-described embodiments, the piston 10 is applied to the engine 11 that is an internal combustion engine, and the piston 10 and the piston rings 60 and 62 are applied to the engine 64 that is an internal combustion engine. For example, at least one of the piston 10 and the piston rings 60 and 62 may be applied to an external combustion engine, a reciprocating (reciprocating) compressor, or the like.

10 piston 10A crown 11 engine (reciprocating device)
30, 32, 33 Piston ring 50 Ring groove 50A Groove bottom 50B Groove wall 50C Groove wall 52, 52A to 52E Oil reservoir groove (recess)
60/62 piston ring 64 engine (reciprocating device)
66 Oil sump groove (concave)

Claims (9)

A ring groove that opens to the outer peripheral side for mounting the piston ring;
In the crown surface side portion in the ring groove, a recess that is opened so that the lubricant can enter and exit,
The piston is formed.   The piston according to claim 1, wherein the recess has an annular shape extending over the entire length of the ring groove.   The piston according to claim 1 or 2, wherein the recess has a cross-sectional shape that opens at a groove bottom of the ring groove and extends from the opening toward the crown surface.   The piston according to any one of claims 1 to 3, wherein the concave portion opens toward a side opposite to the crown surface side with respect to a groove bottom portion of the ring groove.   The recessed portion has a cross-sectional shape that opens toward the outer peripheral side at the groove bottom of the ring groove and has a cross-sectional shape that extends obliquely inward in the radial direction on the crown surface side from the opening. The piston according to any one of the above.   6. A piston ring to be mounted on the piston according to claim 5, further comprising a recess that opens at an inner peripheral surface so as to face the recess and extends obliquely outward in the radial direction on the crown surface side. piston ring.   A piston ring provided with a recess that is opened on an inner peripheral surface so as to face a ring groove of the piston and that extends obliquely outward in a radial direction on the crown surface side of the piston. A cylinder,
The piston according to any one of claims 1 to 5, provided in the cylinder so as to be capable of reciprocating,
A piston ring mounted in a ring groove of the piston and sealingly seals between the cylinder and the piston;
A reciprocating device comprising: A cylinder,
The piston according to claim 5, which is provided in the cylinder so as to be reciprocally movable;
The piston ring according to claim 6 or 7, wherein the piston ring is mounted in a ring groove of the piston and seals between the cylinder and the piston in a lubricated state.
A reciprocating device comprising:

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