JP2012241673A - Oil ring and internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil ring and an internal combustion engine, for preventing increase in oil consumption when a lower surface of a lower rail part sticks to an opposite surface of a ring groove.SOLUTION: An oil ring 4 is mounted on a ring groove 3 formed on an outer circumferential surface of a piston 2. The oil ring 4 includes: a pair of upper rail part 51 and lower rail part 52 that slide on a pair of upper surface 31 and a lower surface 32 facing each other in the ring groove 3; and a connecting part 53 connecting the rail parts 51 and 52. In the connecting part 53, an oil return hole 54 is formed which is penetrated in a radial direction of the oil ring 4. On a lower surface of the lower rail part 52, a groove 56 is formed over the circumference immediately below the oil return hole 54. In a ring body 5, a plurality of through holes 57 are formed through the oil return hole 54 and the groove 56. The plurality of through holes 57 are formed at equal intervals in a circumferential direction of the oil ring 4.

Description

  The present invention relates to an oil ring mounted in a ring groove formed on an outer peripheral surface of an engine piston and an internal combustion engine including the oil ring.

  A piston is provided in a cylinder of the internal combustion engine so as to be able to reciprocate. Piston rings are mounted in a plurality of ring grooves formed on the outer peripheral surface of the piston. Specifically, a top ring, a second ring, and an oil ring are mounted in the order closer to the combustion chamber in the axial direction of the piston (see, for example, Patent Document 1).

  The top ring and the second ring have a function of sealing between the combustion gas generated in the combustion chamber so as not to leak from between the piston and the cylinder. In general, the top ring and the second ring are collectively referred to as a compression ring.

The oil ring has a function of supplying engine oil to the cylinder bore wall surface by a necessary minimum amount and scraping off excess oil.
As shown in FIG. 6, the oil ring 404 includes a ring main body 405 and a coil expander 6 that is positioned on the inner peripheral side of the ring main body 405 and biases the ring main body 405 toward the outer peripheral side. The ring body 405 includes an upper rail portion 451 that can slide on the upper facing surface 31 of the ring groove 3, a lower rail portion 452 that can slide on the lower facing surface 32 that faces the upper facing surface 31, and these And a connecting portion 453 that connects the rail portions 451 and 452. These rail portions 451 and 452 protrude from the connecting portion 453 to both the inner peripheral side and the outer peripheral side. That is, the ring main body 405 has a substantially I-shaped cross section. The connecting portion 453 is formed with a plurality of oil return holes 454 penetrating in the radial direction of the oil ring 404. The oil return holes 454 are formed at predetermined intervals in the circumferential direction of the oil ring 404. The inner peripheral surface of the connecting portion 453 is formed in an arc shape in cross section, and serves as a housing portion 455 in which the coil expander 6 is housed.

  In the internal combustion engine including such an oil ring 404, the outer peripheral surfaces of the upper rail portion 451 and the lower rail portion 452 slide on the bore wall surface 1 of the cylinder as the piston 2 reciprocates, thereby adhering to the bore wall surface 1. The excess oil is scraped off and introduced into the ring groove 3 through the oil return hole 454. The oil in the ring groove 3 is returned to the crankcase through a discharge passage (not shown) formed in the bottom surface 33 of the ring groove 3.

JP 2006-322390 A

  By the way, as shown as periods A1 and A2 in FIG. 7, when the piston 2 moves upward and the acceleration of the piston 2 is positive, that is, when the upward speed increases, the oil ring 404 in the ring groove 3 and The oil is pressed against the lower facing surface 32. After that, as shown in FIGS. 7A and 7B as periods B1 and B2, when the piston 2 moves upward and the acceleration of the piston 2 becomes negative, that is, the speed toward the upper side decreases, as shown in FIG. 3 immediately moves relative to the upper facing surface 31. At this time, since the lower surface of the lower rail portion 452 is in close contact with the lower facing surface 32, a certain amount of time is required until the ring body 405 is detached from the lower facing surface 32. As a result, the oil moving in the vicinity of the upper facing surface 31 flows out through the gap between the upper surface of the upper rail portion 451 and the upper facing surface 31, and flows upward from the gap between the outer peripheral surface of the piston 2 and the bore wall surface 1. As a result, the problem of increased oil consumption arises.

  The present invention has been made in view of such circumstances, and its purpose is to suppress an increase in oil consumption due to the lower surface of the lower rail portion sticking to the opposing surface of the ring groove. It is to provide an oil ring and an internal combustion engine that can be used.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention according to claim 1 is an oil ring mounted in a ring groove formed on the outer peripheral surface of the engine piston, and a pair of slidable surfaces on a pair of opposed surfaces facing each other in the ring groove. In the oil ring having a rail part and a connecting part for connecting the rail part, an oil return hole penetrating in the radial direction of the oil ring is formed in the connecting part, and the oil ring of the oil ring is formed in the pair of rail parts. A through-hole opened in the lower surface of the lower rail portion when the combustion chamber side in the axial direction is the upper rail portion and the lower rail portion is the opposite side of the combustion chamber in the coaxial line direction It is the gist that it is formed.

  According to this configuration, when the lower surface of the lower rail portion is to be adhered and adhered to the opposing surface of the ring groove, the lower rail portion is interposed between the lower surface and the opposing surface through the through-hole formed in the lower rail portion. Air and oil are introduced. As a result, the lower surface of the lower rail portion is less likely to adhere to the opposing surface of the ring groove, and the force to attach the lower rail portion is weakened. To come apart. For this reason, if the oil in the ring groove moves relative to the upper facing surface after the acceleration of the engine piston is reversed from upward to downward, the oil ring follows this, and the upper surface of the upper rail portion is It comes into early contact with the upper facing surface of the groove. As a result, it is possible to suppress the oil inside the ring groove from flowing out to the combustion chamber through between the upper surface and the opposing surface. Therefore, it is possible to suppress an increase in oil consumption due to the lower surface of the lower rail portion sticking to the opposing surface of the ring groove.

  According to a second aspect of the present invention, in the oil ring according to the first aspect, a groove is formed on the entire lower surface of the lower rail portion, and the through hole is opened to the groove. It is a summary.

  According to this configuration, air or oil is introduced between the lower surface and the opposing surface over the entire circumference through the groove. Thereby, the force which sticks the lower surface of a lower rail part with respect to the opposing surface of a ring groove is weakened over a perimeter. For this reason, the lower surface of the lower rail part comes off early and accurately from the facing surface of the ring groove.

  The gist of the invention according to claim 3 is that in the oil ring according to claim 1 or claim 2, a plurality of the through holes are formed in the circumferential direction of the oil ring.

  According to this configuration, air and oil are introduced into the plurality of portions where the through holes are formed between the lower surface of the lower rail portion and the opposing surface of the ring groove. Thereby, the force which sticks the lower surface of a lower rail part with respect to the opposing surface of a ring groove is weakened suitably. In order to evenly weaken the force to be applied in the circumferential direction of the oil ring, it is desirable to form a plurality of through holes at equal intervals in the circumferential direction of the oil ring.

  The gist of the invention according to claim 4 is that, in the oil ring according to any one of claims 1 to 3, one of the through holes is open to the oil return hole. .

According to this configuration, the through hole can be formed along the axial direction of the oil ring, and therefore the through hole can be easily formed.
According to a fifth aspect of the present invention, in the oil ring according to any one of the first to fourth aspects, a through-hole penetrating the oil return hole and the upper surface of the upper rail portion is formed. That is the gist.

  According to this configuration, the through hole is formed between the oil return hole and the lower surface of the lower rail portion, and is formed between the oil return hole and the upper surface of the upper rail portion. For this reason, when assembling the oil ring into the ring groove, the vertical relationship does not become a problem. Therefore, the oil ring can be easily assembled to the ring groove.

The gist of the invention described in claim 6 is the internal combustion engine provided with the oil ring according to any one of claims 1 to 5.
According to this configuration, it is possible to achieve the operational effects according to the invention described in any one of claims 1 to 5.

  The invention according to claim 7 includes an engine piston and an oil ring mounted in a ring groove formed on an outer peripheral surface of the engine piston, and the oil ring is a pair of opposed surfaces facing each other in the ring groove. An internal combustion engine having a pair of rail portions that can slide on each other and a connecting portion that connects the rail portions, and the upper rail portion of the pair of rail portions that is on the combustion chamber side in the axial direction of the oil ring. And the one on the opposite side of the combustion chamber in the coaxial line direction as the lower rail portion, one side opens to the opposite surface of the ring groove facing the lower surface of the lower rail portion, and The gist thereof is that a communication hole having the other opening is formed in at least one of the outer peripheral surface and the inner peripheral surface.

  According to this configuration, when the lower surface of the lower rail portion is to be adhered and adhered to the opposing surface of the ring groove, air or air is interposed between the opposing surface and the lower surface through the communication hole formed in the engine piston. Oil is introduced. As a result, the lower surface of the lower rail portion is less likely to adhere to the opposing surface of the ring groove, and the force to attach the lower rail portion is weakened. To come apart. For this reason, if the oil in the ring groove moves relative to the upper facing surface after the acceleration of the engine piston is reversed from upward to downward, the oil ring follows this, and the upper surface of the upper rail portion is It comes into early contact with the upper facing surface of the groove. As a result, it is possible to suppress the oil inside the ring groove from flowing out to the combustion chamber through between the upper surface and the opposing surface. Therefore, it is possible to suppress an increase in oil consumption due to the lower surface of the lower rail portion sticking to the opposing surface of the ring groove.

  According to an eighth aspect of the present invention, in the internal combustion engine according to the seventh aspect of the present invention, a groove is formed on the entire surface of the ring groove facing the lower surface of the lower rail portion, and the communication hole includes the communication hole. The gist is that the groove is open.

  According to this configuration, air or oil is introduced between the facing surface and the lower surface over the entire circumference through the groove. Thereby, the force which sticks the lower surface of a lower rail part with respect to the opposing surface of a ring groove is weakened over a perimeter. For this reason, the lower surface of the lower rail part comes off early and accurately from the facing surface of the ring groove.

The invention according to claim 9 is characterized in that, in the internal combustion engine according to claim 7 or claim 8, a plurality of the communication holes are formed in the circumferential direction of the ring groove.
According to this configuration, air and oil are introduced into the plurality of portions where the communication holes are formed between the facing surface of the ring groove and the lower surface of the lower rail portion. Thereby, the force which sticks the lower surface of a lower rail part with respect to the opposing surface of a ring groove is weakened suitably. In order to evenly weaken the affixing force in the circumferential direction of the oil ring, it is desirable to form a plurality of communication holes at equal intervals in the circumferential direction of the ring groove.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the cross-section of the cylinder centering on an oil ring about 1st Embodiment of the oil ring and internal combustion engine which concerns on this invention. Schematic for demonstrating the effect | action of the oil ring in the embodiment. Sectional drawing which shows the cross-section of a cylinder centering on an oil ring about 2nd Embodiment of this invention. Sectional drawing which shows the cross-section of the cylinder centering on the oil ring in 3rd Embodiment of this invention. Sectional drawing which shows the cross-section of a cylinder centering on an oil ring about the modification of 3rd Embodiment. Sectional drawing which shows the cross-section of the cylinder centering on the conventional oil ring. The timing chart which shows the transition of the phase of a piston, speed, and acceleration together. Schematic for demonstrating the subject of the conventional oil ring.

<First Embodiment>
Hereinafter, a first embodiment embodying an oil ring and an internal combustion engine according to the present invention will be described with reference to FIGS. 1 and 2.

  In the following, the direction close to the combustion chamber in the axial direction C of the oil ring 4 (piston 2) is simply referred to as “upward”, and the direction away from the combustion chamber in the axial direction C, that is, the direction close to the crankcase is simply downward. Called.

  As shown in FIG. 1, a piston 2 is provided in a cylinder of the internal combustion engine so as to be able to reciprocate. An oil ring 4 is mounted in a ring groove 3 formed on the outer peripheral surface of the piston 2. The oil ring 4 is a so-called two-piece oil ring, and includes a ring main body 5 and a coil expander 6 that is positioned on the inner peripheral side of the ring main body 5 and biases the ring main body 5 toward the outer peripheral side.

  The ring body 5 includes a lower rail 51 that can slide on the upper facing surface 31 of the ring groove 3 and a lower sliding surface 32 that faces the upper facing surface 31 in the axial direction C of the piston 2. It has the side rail part 52 and the connection part 53 which connects these rail parts 51 and 52. As shown in FIG. These rail portions 51 and 52 protrude from the connecting portion 53 both on the inner peripheral side and on the outer peripheral side. That is, the ring body 5 has a substantially I-shaped cross section. The connecting portion 53 is formed with a plurality of oil return holes 54 penetrating in the radial direction of the oil ring 4. The oil return holes 54 are formed at predetermined intervals in the circumferential direction of the oil ring 4. The inner peripheral surface of the connecting portion 53 is formed in an arc shape in cross section, and serves as a housing portion 55 in which the coil expander 6 is housed.

  In the present embodiment, a groove 56 is formed on the entire lower surface of the lower rail portion 52 directly below the oil return hole 54. Further, in the lower rail portion 52, the portion other than the groove 56 out of the portion facing the lower facing surface 32 has a flat shape, and when the portion is displaced downward in the ring groove 3, the entire portion is on the lower side. It is supposed to abut against the facing surface 32.

  The ring body 5 is formed with a plurality of through holes 57 that penetrate the oil return hole 54 and the groove 56. Here, the plurality of through holes 57 are formed along the axial direction C of the oil ring 4 and are formed at equal intervals in the circumferential direction of the oil ring 4.

Next, the operation of this embodiment will be described.
In the internal combustion engine having such an oil ring 4, the outer peripheral surfaces of the upper rail portion 51 and the lower rail portion 52 slide on the bore wall surface 1 of the cylinder as the piston 2 reciprocates, thereby adhering to the bore wall surface 1. The excess oil is scraped off and introduced into the ring groove 3 through the oil return hole 54. The oil in the ring groove 3 is returned to the crankcase through a discharge passage (not shown) formed in the bottom surface 33 of the ring groove 3.

  When the piston 2 moves upward and the acceleration of the piston 2 is positive, that is, when the upward speed increases, as shown in the periods A1 and A2 in FIG. 7, the oil ring in the ring groove 3 is increased. 4 and the oil are pressed against the lower facing surface 32. Here, in the present embodiment, when the lower surface of the lower rail portion 52 is to adhere to and adhere to the lower facing surface 32 of the ring groove 3, the through hole 57 and the groove 56 formed in the oil ring 4. Air and oil are introduced over the entire circumference between the lower surface of the lower rail portion 52 and the lower facing surface 32. Thereby, the lower surface of the lower rail portion 52 is less likely to be in close contact with the lower facing surface 32, and the force for attaching the lower rail portion 52 is weakened.

  Thereafter, as shown as periods B1 and B2 in FIG. 7, when the piston 2 moves upward and the acceleration of the piston 2 becomes negative, that is, the speed toward the upper side decreases, the oil in the ring groove 3 is immediately reduced. Relative movement toward the upper facing surface 31. At this time, as shown in FIG. 2, the lower surface of the lower rail portion 52 is detached early from the lower facing surface 32 of the ring groove 3. For this reason, when the oil in the ring groove 3 relatively moves toward the upper facing surface 31 after the acceleration of the piston 2 is reversed from the upward direction to the downward direction, the ring main body 5 follows this, and the upper rail portion 51 The upper surface comes into early contact with the upper facing surface 31 of the ring groove 3. As a result, the gap between the upper surface of the upper rail portion 51 and the upper facing surface 31 is sealed, so that the oil in the ring groove 3 is prevented from flowing out.

According to the oil ring and the internal combustion engine according to the present embodiment described above, the following effects can be obtained.
(1) An oil return hole 54 penetrating in the radial direction of the oil ring 4 is formed in the connecting portion 53, and a through hole 57 penetrating the oil return hole 54 and the lower surface of the lower rail portion 52 is formed. According to such a configuration, when the oil in the ring groove 3 relatively moves toward the upper facing surface 31 after the acceleration of the piston 2 is reversed from upward to downward, the ring main body 5 follows this, and the upper rail The upper surface of the part 51 comes into early contact with the upper facing surface 31 of the ring groove 3. As a result, it is possible to suppress the oil inside the ring groove 3 from flowing out to the combustion chamber side through between the upper surface of the upper rail portion 51 and the upper facing surface 31. Therefore, it is possible to suppress an increase in oil consumption due to the lower surface of the lower rail portion 52 sticking to the lower facing surface 32 of the ring groove 3.

  (2) A groove 56 is formed on the entire lower surface of the lower rail portion 52, and the through hole 57 is open to the groove 56. According to such a configuration, air or oil is introduced between the lower surface of the lower rail portion 52 and the lower facing surface 32 through the groove 56 over the entire circumference. Thereby, the force which sticks the lower surface of the lower rail part 52 with respect to the lower side opposing surface 32 of the ring groove 3 is weakened over a perimeter. For this reason, the lower surface of the lower rail part 52 comes off early and accurately from the lower facing surface 32 of the ring groove 3.

  (3) A plurality of through holes 57 are formed at equal intervals in the circumferential direction of the oil ring 4. According to such a configuration, air and oil are introduced into a plurality of portions where the through holes 57 are formed between the lower surface of the lower rail portion 52 and the lower facing surface 32 of the ring groove 3. As a result, the force for attaching the lower surface of the lower rail portion 52 to the lower facing surface 32 of the ring groove 3 is evenly weakened in the circumferential direction of the oil ring 4.

  (4) One of the through holes 57 opens into the oil return hole 54. According to such a configuration, since the through hole 57 can be formed along the axial direction C of the oil ring 4, the through hole 57 can be easily formed.

Second Embodiment
Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
In the present embodiment, the configuration other than the ring main body 105 is the same as that of the first embodiment. Accordingly, the same components as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted. Further, in the configuration of the ring main body 105, the configuration corresponding to the configuration of the ring main body 5 of the first embodiment is denoted by a reference numeral added with “100”, and redundant description is omitted.

  As shown in FIG. 3, in the present embodiment, a groove 156 is formed over the entire circumference just below the oil return hole 154 on the lower surface of the lower rail portion 152, as in the first embodiment. The ring body 105 is formed with a plurality of through holes 157 that penetrate the oil return holes 154 and the grooves 156. Here, the plurality of through holes 57 are formed at equal intervals in the circumferential direction of the oil ring 104.

  Further, an upper groove 158 is formed over the entire circumference immediately above the oil return hole 154 on the upper surface of the upper rail portion 151. The ring main body 105 is formed with a plurality of upper through holes 159 that pass through the oil return holes 154 and the upper grooves 158. Here, the plurality of upper through holes 159 are formed corresponding to the plurality of through holes 157, respectively, and are formed at equal intervals in the circumferential direction of the oil ring 104.

According to the oil ring and the internal combustion engine according to the present embodiment described above, the following functions and effects can be newly obtained in addition to the functions and effects (1) to (4) of the first embodiment.
(5) An upper through hole 159 that penetrates the oil return hole 154 and the upper surface of the upper rail portion 151 is formed. Specifically, an upper groove 158 is formed over the entire upper surface of the upper rail portion 151, and the upper through hole 159 opens into the upper groove 158. According to such a configuration, the through holes 157 and 159 are formed between the oil return hole 154 and the lower surface of the lower rail portion 152, and are formed between the oil return hole 154 and the upper surface of the upper rail portion 151. ing. For this reason, when assembling the oil ring 104 into the ring groove 3, the vertical relationship of the oil ring 104 does not become a problem. Therefore, the oil ring 104 can be easily assembled to the ring groove 3.

<Third Embodiment>
Hereinafter, a third embodiment of the internal combustion engine according to the present invention will be described with reference to FIG.

  In this embodiment, the configuration of the oil ring is the same as that of the conventional oil ring 404 illustrated in FIG. Therefore, in this embodiment, the description about an oil ring is omitted by attaching the same reference numerals as in FIG. Further, the piston 202 is partially different from the piston 2 illustrated in the prior art illustrated in FIG. 6 and the first and second embodiments described above. For this reason, about the structure corresponding to the structure of the piston 2 of 1st Embodiment, the overlapping description is omitted by attaching | subjecting the code | symbol which added "200".

  As shown in FIG. 4, a groove 234 is formed over the entire circumference of the lower facing surface 232 of the ring groove 203 immediately below the oil return hole 454 of the oil ring 404. Of the portion facing the lower rail portion 52 on the lower facing surface 32, the portion other than the groove 234 has a flat surface shape, and the portion when the ring main body 405 is displaced downward in the ring groove 203. The whole is in contact with the lower rail portion 52.

  The piston 202 is formed with a communication hole 235, one of which opens into the groove 234 and the other of which opens into the inner peripheral surface of the piston 202. Here, the plurality of communication holes 235 are formed at equal intervals in the circumferential direction of the ring groove 203.

Next, the operation of this embodiment will be described.
As shown in FIGS. 7A and 7B as periods A1 and A2, when the piston 202 moves upward and the acceleration of the piston 202 is positive, that is, when the upward speed increases, the oil ring 404 and the ring groove 203 in the ring groove 203 The oil is pressed against the lower facing surface 232. Here, in the present embodiment, when the lower surface of the lower rail portion 452 is to be in close contact with the lower facing surface 232 of the ring groove 203, the through hole 235 and the groove 234 formed in the piston 202 are used. Air and oil are introduced over the entire circumference between the lower surface of the lower rail portion 452 and the lower facing surface 232. As a result, the lower surface of the lower rail portion 452 is less likely to be in close contact with the lower facing surface 232, and the force to attach the lower rail portion 452 is weakened.

  After that, as shown as periods B1 and B2 in FIG. 7, when the piston 202 moves up and the acceleration of the piston 202 becomes negative, that is, the speed toward the upper side decreases, the oil in the ring groove 203 is immediately increased. It moves relative to the upper facing surface 231. At this time, the lower surface of the lower rail portion 452 comes off early from the lower facing surface 232 of the ring groove 203. For this reason, if the oil in the ring groove 203 relatively moves toward the upper facing surface 231 after the acceleration of the piston 202 is reversed from upward to downward, the ring main body 405 follows this, and the upper rail portion 451 The upper surface comes into early contact with the upper facing surface 231 of the ring groove 203. As a result, the gap between the upper surface of the upper rail portion 451 and the upper facing surface 231 is sealed, so that the oil in the ring groove 203 is suppressed from flowing out.

According to the internal combustion engine according to the present embodiment described above, the following operational effects can be obtained.
(6) A communication hole 235 is formed in the lower facing surface 232 of the ring groove 203, and one is opened in the inner peripheral surface of the piston 202. According to such a configuration, when the oil in the ring groove 203 relatively moves toward the upper facing surface 231 after the acceleration of the piston 202 is reversed from upward to downward, the ring main body 405 follows this, and the upper rail The upper surface of the portion 451 comes into early contact with the upper facing surface 231 of the ring groove 203. As a result, it is possible to prevent oil in the ring groove 203 from flowing out between the upper surface of the upper rail portion 451 and the upper facing surface 231. Therefore, it is possible to suppress an increase in oil consumption due to the lower surface of the lower rail portion 452 sticking to the lower facing surface 232 of the ring groove 203.

  (7) A groove 234 is formed over the entire periphery of the lower facing surface 232 of the ring groove 203, and the communication hole 235 opens into the groove 234. According to such a configuration, air or oil is introduced between the lower facing surface 232 and the lower surface of the lower rail portion 452 through the groove 234 over the entire circumference. Thereby, the force which sticks the lower surface of the lower rail part 452 with respect to the lower side opposing surface 232 of the ring groove 203 is weakened over a perimeter. For this reason, the lower surface of the lower rail part 452 comes off early and accurately from the facing surface of the ring groove 203.

  (8) A plurality of communication holes 235 are formed at equal intervals in the circumferential direction of the ring groove 203. According to such a configuration, air and oil are introduced into a plurality of portions where the communication holes 235 are formed between the lower facing surface 232 of the ring groove 203 and the lower surface of the lower rail portion 452. As a result, the force for attaching the lower surface of the lower rail portion 452 to the lower facing surface 232 of the ring groove 203 is evenly weakened in the circumferential direction of the ring groove 203.

  Note that the oil ring and the internal combustion engine according to the present invention are not limited to the configurations exemplified in the above embodiment, and can be implemented as, for example, the following forms appropriately modified.

  As in the first and second embodiments described above, one of the plurality of through holes 57, 157, 159 is opened to the oil return holes 54, 154, and is along the axial direction C of the oil rings 4, 104. It is desirable to make these through holes 57, 157 and 159 easy to form. However, the present invention is not limited to this, and the through hole may not be opened in the oil return hole, that is, may be independent of the oil return hole.

  As in the first and second embodiments, it is possible to form the plurality of through holes 57, 157, 159 at equal intervals in the circumferential direction of the oil ring 4, 104 on the lower facing surface 32 of the ring groove 3. On the other hand, it is desirable to uniformly weaken the force for attaching the lower surfaces of the lower rail portions 52 and 152 in the circumferential direction of the oil rings 4 and 104. However, the present invention is not limited to this, and a plurality of through holes may be formed at unequal intervals.

  In the first and second embodiments and their modifications, a plurality of through holes are formed. However, instead of this, only one through hole may be formed. Even in this case, for example, if a groove is formed in the entire circumferential direction on the lower surface of the lower rail portion, air or oil is introduced over the entire circumference between the lower surface of the lower rail portion and the lower facing surface. Can do.

  As described in the first and second embodiments and the modifications thereof, forming the groove over the entire circumference on the lower surface of the lower rail portion may cause the lower rail portion to It is desirable to weaken the force for attaching the lower surface over the entire circumference. However, the present invention is not limited to this, and the oil ring of the oil ring can be used as long as the force for attaching the lower surface of the lower rail portion to the lower facing surface of the ring groove can be sufficiently weakened. You may make it form a groove | channel partially in the circumferential direction.

  -One of the communication holes 235 of the third embodiment is opened to the groove 234 and the other is opened to the inner peripheral surface of the piston 202. Instead, as shown in FIG. The other of the holes 335 may be opened on the outer peripheral surface of the piston 302. Further, the groove 334 is formed over the entire circumference on the lower facing surface 332.

  As in the third embodiment, the plurality of communication holes 235 are formed at equal intervals in the circumferential direction of the ring groove 203 so that the lower rail portion 452 can be formed with respect to the lower facing surface 232 of the ring groove 203. This is desirable in order to uniformly weaken the force for attaching the lower surface in the circumferential direction of the ring groove 203. However, the present invention is not limited to this, and a plurality of communication holes may be formed at unequal intervals.

  In the third embodiment and its modification, a plurality of communication holes are formed, but instead, only one communication hole may be formed. Even in this case, for example, if a groove is formed in the entire circumferential direction on the lower facing surface, air or oil may be introduced over the entire circumference between the lower surface of the lower rail portion and the lower facing surface. I can.

  -As in the third embodiment and the modification thereof, the formation of the groove over the entire circumference on the lower facing surface is a force for attaching the lower surface of the lower rail portion to the lower facing surface of the ring groove. It is desirable to weaken all over the circumference. However, the present invention is not limited to this, and if the force for attaching the lower surface of the lower rail portion to the lower facing surface of the ring groove can be sufficiently weakened, the circumference of the ring can be reduced. You may make it form a groove | channel partially in a direction.

  DESCRIPTION OF SYMBOLS 1 ... Bore wall surface, 2,202,302 ... Piston, 3,203,303 ... Ring groove, 31,231,331 ... Upper facing surface, 32,232,332 ... Lower facing surface, 33,233,333 ... Bottom surface 4, 104, 404 ... oil ring, 5, 105, 405 ... ring main body, 51, 151, 451 ... upper rail part, 52, 152, 452 ... lower rail part, 53, 153, 453 ... connecting part, 54 , 154, 454 ... oil return hole, 55, 155, 455 ... receiving portion, 56, 156 ... groove, 57, 157 ... through hole, 158 ... upper groove, 159 ... upper through hole, 6 ... coil expander, 234 334... Groove, 235 and 335.

Claims (9)

An oil ring mounted in a ring groove formed on the outer peripheral surface of the engine piston, and a pair of rail portions that can slide on a pair of opposed surfaces facing each other in the ring groove, and these rail portions are connected In an oil ring having a connecting part to
The connecting portion is formed with an oil return hole penetrating in the radial direction of the oil ring,
When the combustion chamber side in the axial direction of the oil ring in the pair of rail portions is the upper rail portion and the opposite side of the combustion chamber in the coaxial line direction is the lower rail portion,
The lower rail part is formed with a through-hole that opens in the lower surface thereof. The oil ring according to claim 1,
A groove is formed on the entire lower surface of the lower rail portion,
The oil ring, wherein the through hole is opened in the groove. In the oil ring according to claim 1 or 2,
A plurality of the through holes are formed in the circumferential direction of the oil ring. In the oil ring according to any one of claims 1 to 3,
One of the through holes is open to the oil return hole. In the oil ring according to any one of claims 1 to 4,
A through-hole penetrating the oil return hole and the upper surface of the upper rail portion is formed.   An internal combustion engine comprising the oil ring according to any one of claims 1 to 5. An engine piston and an oil ring mounted in a ring groove formed on the outer peripheral surface of the engine piston, and the oil ring is slidable on a pair of opposed surfaces facing each other in the ring groove. In an internal combustion engine having a rail portion and a connecting portion that connects these rail portions,
When the combustion chamber side in the axial direction of the oil ring in the pair of rail portions is the upper rail portion and the opposite side of the combustion chamber in the coaxial line direction is the lower rail portion,
One opening is formed on the facing surface of the ring groove facing the lower surface of the lower rail part, and a communication hole is formed on at least one of the outer peripheral surface and the inner peripheral surface of the engine piston. An internal combustion engine. The internal combustion engine according to claim 7,
Grooves are formed over the entire circumference on the facing surface of the ring groove facing the lower surface of the lower rail portion,
The internal combustion engine, wherein the communication hole is opened in the groove. The internal combustion engine according to claim 7 or claim 8,
An internal combustion engine characterized in that a plurality of the communication holes are formed in the circumferential direction of the ring groove.

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