JP2000045862A - Piston ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of sealability to resin piston ring which is caused by combustion pressure. SOLUTION: In an outer ring 2, a tip end surface 10a of a lower projection streak 10 is less than a tip end surface 8a of an upper projection streak 8 in width. More deteriorative pressure is applied to an inner peripheral surface 20a of a cylinder 20 comparing with that of the tip end surface 10a of the lower projection streak 10. The tip end surface 8a of the upper projection streak 8 which substantially directly receives combustion pressure has large width and shows stable stance for a long time. Twisting of the outer ring 2 caused by combustion pressure is thus effectively prevented. Since the pressure on the tip end surface 10a of the lower projection streak 10 is higher than that on the tip end surface 8a of the upper projection streak 8, adhesiveness to the inner peripheral surface 20a of the cylinder 20 is improved. Engine oil is prevented from leaking from the side of a crank case to a combustion chamber side. Deterioration of sealability is thus sufficiently prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston ring, and more particularly to a piston ring which is disposed in a ring groove formed in a circumferential direction on a peripheral surface of a piston and is pressed against an inner peripheral surface of a reciprocating cylinder. The present invention relates to a resin-made piston ring that prevents leakage of high-pressure gas existing in a space defined by a piston and a cylinder.

[0002]

2. Description of the Related Art In an internal combustion engine, a resin-made piston ring having no abutment is used in order to improve sealing performance. For example, Japanese Patent Application Laid-Open No. 9-159023,
Japanese Patent Application Laid-Open No. 8-226542 describes a piston ring structure provided with a resin piston ring, a resin elastic ring more elastic than the piston ring, and a coil expander.

[0003] Such a resin-made piston ring can not only prevent the formation of an abutment, but also has high follow-up properties with respect to thermal deformation of a cylinder bore due to its high deformability. It is extremely high compared to a piston ring, and is effective in improving fuel efficiency.

[0004]

However, due to such high sealing performance, the piston ring is subjected to a particularly high combustion pressure from the combustion chamber. Therefore, FIG.
As shown in FIG. 3A, the internal combustion engine is actually operated despite that the sliding surfaces 704 and 706 of the piston ring 702 are arranged so as to appropriately abut against the inner peripheral surface 708 of the cylinder. As shown in FIG. 13B, the sliding surfaces 704 and 706 of the piston ring 702 are pressed toward the crankcase side, so that the piston ring 702 is pressed.
(In particular, the outer ring in this case) is swung so as to twist to the crankcase side, and the sliding surface 70 on the crankcase side is rotated.
6 occur from the cylinder inner peripheral surface 708 or the pressure on the cylinder inner peripheral surface 708 decreases.

[0005] When the crankcase side of the piston ring 702 rises or the pressure decreases in this way, the oil adhering to the cylinder inner peripheral surface 708 where the sliding surface 706 of the crankcase side mainly works is transferred to the crankcase side. The effect of scraping down is reduced. Further, on the other hand, the action of scraping up oil toward the combustion chamber occurs on the sliding surface 704 on the combustion chamber side, and the oil enters the combustion chamber,
There is a problem that the oil sealability is reduced.

As described above, even a resin-made piston ring having an abutment has a high follow-up property with respect to the cylinder bore, and therefore has a higher sealing property against combustion gas than a metal-made piston ring. For this reason, even in the case where there is an abutment, in the case of a resin piston ring, the above-described torsion is likely to occur similarly, which may cause a problem in oil sealability.

In the case of a metal piston ring, since the piston ring itself is a rigid body, the problem of torsion itself does not occur as in the case of the resin piston ring described above, and the piston ring is used as an oil ring which is not affected by the combustion pressure. And various configurations of the metal piston ring (JP-A-7-239031, JP-A-8-42).
No. 693), but does not provide a reference for measures against the above-described problem of the resin piston ring.

An object of the present invention is to prevent a decrease in sealing performance due to the action of a pressure such as a combustion pressure on a resin piston ring.

[0009]

The piston ring according to the first aspect of the present invention is arranged in a ring groove formed in a circumferential direction on the peripheral surface of the piston, and is pressed against the inner peripheral surface of the cylinder in which the piston reciprocates. A resin-made piston ring for preventing leakage of high-pressure gas existing in a space defined by a piston and a cylinder, wherein a pressure generated by the pressing is set in a sliding surface abutting on an inner peripheral surface of the cylinder. , Characterized by being higher on the side opposite to the space than on the space side.

In the present piston ring, the pressure on the inner peripheral surface of the cylinder is higher on the side opposite to the space than on the side of the space, of the sliding surfaces abutting on the inner peripheral surface of the cylinder. . The pressure of the high-pressure gas in the space acts on the piston ring to lower the sliding surface side of the piston ring to the opposite side to the space, but from the sliding surface of the piston ring to the inner circumferential surface of the cylinder. Is biased toward the opposite side to the space, a moment in the opposite direction to the torsional moment generated by the high-pressure gas is generated in the piston ring. For this reason, the moment of torsion by the high-pressure gas is weakened, and the phenomenon that the sliding surface on the opposite side to the space rises or the pressure decreases is prevented. Therefore, it is possible to prevent a decrease in sealing performance without hindering the function of scraping oil or the like to the opposite side of the space.

Further, in the first aspect, even when the pressure is higher on the side opposite to the space, the total force may be smaller than that on the space side. Cannot be the moment in the opposite direction to the torsional moment caused by the high pressure gas. However, even in such a case, it is possible to prevent the sealing performance from being lowered by the following configuration.

That is, the piston ring of claim 2 is
With respect to the configuration according to claim 1, at least two ridges projecting toward the cylinder and having a front end surface abutting on the inner peripheral surface of the cylinder as a sliding surface are formed over the entire circumference and the space. The width of the ridge tip surface on the side opposite to the space is formed smaller than the width of the ridge tip surface on the side, so that the pressure slides on the cylinder inner peripheral surface. It is characterized in that, on the surface, the side opposite to the space is higher than the space side.

As described above, the sliding surface on the space side, which receives a high pressure from the space side, has a large effect of maintaining a stable posture because the width is larger than the sliding surface on the opposite side. Can be prevented. This allows
Since the opposite sliding surface can be prevented from rising from the cylinder or reducing the pressure, good sealing performance can be maintained.

Further, even if the total pressure of the sliding surfaces on the space side and the opposite side is the same as the total force, the posture stability by the sliding surface on the space side becomes higher. Further, since the sliding surface on the side opposite to the space side has a high pressure on the cylinder inner peripheral surface, the adhesion to the cylinder inner peripheral surface is increased, and oil is prevented from entering the space side. The effect is higher. Therefore, it is possible to sufficiently prevent a decrease in sealing performance.

According to a third aspect of the present invention, in the piston ring according to the first aspect, the pressure is provided by an expander which is disposed in a ring groove and presses the piston ring against the inner peripheral surface of the cylinder. The pressing center is biased to the opposite side to the space from the center of the piston ring, so that the pressure is higher than the space side of the sliding surface abutting on the cylinder inner peripheral surface. It is characterized in that the side opposite to the space is raised.

As described above, since the center of pressing of the expander is deviated to the opposite side of the space from the center of the piston ring, not only the height of the pressure but also the total force of the pressing force is reduced in the space. It is distributed more to the sliding surface on the opposite side, preventing twisting due to high-pressure gas, and also increasing the adhesion to the cylinder inner peripheral surface, making it possible to further improve the sealing performance. it can.

According to a fourth aspect of the present invention, in the piston ring according to the third aspect, at least two ridges projecting toward the cylinder and having a front end surface abutting on the inner peripheral surface of the cylinder as a sliding surface. Are formed over the entire circumference.

As described above, even with a piston ring having two or more protruding ridges as the sliding surfaces, the effects described in claim 3 can be obtained. Moreover, in this case, the distal end surface of the ridge on the space side can sufficiently prevent leakage of high-pressure gas even if the pressure is low.
Since the tip surface of the opposite ridge has high pressure, the effect of scraping off the oil can be sufficiently exhibited. In this way, each can sufficiently fulfill a role, and a labyrinth effect is also generated by the space between two or more ridges, so that the sealing performance can be further improved.

According to a fifth aspect of the present invention, in the piston ring according to the first aspect, at least two ridges projecting toward the cylinder and having a front end surface abutting on the inner peripheral surface of the cylinder as a sliding surface. Is formed over the entire circumference, and the outer diameter of the ridge tip surface on the space side in the actual machine operation state is smaller than the outer diameter of the ridge tip surface on the side opposite to the space. The pressure is higher on the side opposite to the space than on the space side, of the sliding surface abutting on the inner peripheral surface of the cylinder. I do.

Due to the difference in outer diameter at the leading end surface of the ridge, the pressure on the sliding surface of the ridge on the side opposite to the space is increased, so that the operational effect of claim 1 can be produced. it can. In addition, the distal end surface of the ridge on the space side can play a role of preventing leakage of high-pressure gas even if the pressure is low or not in contact with the inner peripheral surface of the cylinder, and the ridge on the opposite side can be formed. Since the pressure on the tip surface is high, the effect of scraping off the oil can be sufficiently exerted. Therefore, each ridge tip surface can sufficiently fulfill each role, and the sealing performance can be further improved.

According to a sixth aspect of the present invention, in the piston ring according to the fifth aspect, the width of the distal end face on the side opposite to the space is larger than the width of the distal end face on the space side. It is characterized by being formed large.

In this way, the width of the ridge tip surface, which is sufficiently pressed against the inner peripheral surface of the cylinder, is formed to be large, so that the piston ring has a posture in addition to the effect of claim 5. It is possible to secure a stable and better sealing property.

[0023] The piston ring according to the seventh aspect is characterized in that:
A feature is that no abutment is formed with respect to the configuration of any one of 6. As described above, the resin-made piston ring having no abutment is particularly likely to be twisted because it is easily subjected to high pressure as described above. It is.

[0024] The piston ring according to the eighth aspect is characterized in that:
7 is characterized in that the piston ring structure is formed as an outer ring member in a piston ring structure including a plurality of ring members.

The above-described piston ring may be used not only alone but also as a piston ring structure together with other ring-shaped members, and as described above, it is possible to prevent a decrease in sealing performance. .
In addition, when used in a part of the piston ring structure, the width in the radial direction is small and the torsion is likely to occur due to the pressure from the high-pressure gas. The effect is remarkable.

In the ninth aspect, the piston ring according to the first aspect is provided.
3. The configuration according to any one of 3, wherein three protruding ridges projecting toward the cylinder side and having a front end surface abutting on the inner peripheral surface of the cylinder as a sliding surface are formed over the entire circumference. I do.

As described above, even with a piston ring in which the tip surfaces of the three ridges are used as the sliding surfaces, the effects described in claims 1 to 3 are produced. Moreover, in this case, the distal end surface of the ridge on the space side can sufficiently prevent the leakage of high-pressure gas even if the pressure is low, and the distal end surface of the ridge on the opposite side has a high pressure. The effect of scraping off the oil can be sufficiently exhibited. Moreover, the central ridge assists in preventing leakage of high-pressure gas and scraping off oil by this intermediate function. Therefore, each can play a sufficient role, and there is also a labyrinth effect due to the two spaces between the ridges, so that the sealing performance can be further improved.

According to a tenth aspect of the present invention, there is provided a piston ring according to the first aspect.
In addition to any one of the above configurations, a side rail is provided in the ring groove adjacent to the resin piston ring on the side opposite to the space and slides with the cylinder inner peripheral surface. It is characterized by having.

By providing the side rail adjacent to the space opposite to the space as described above, the action of scraping oil by the present piston ring can be increased. An eleventh aspect of the present invention is the piston ring according to the tenth aspect, wherein the piston ring doubles as an oil ring and a compression ring.

This makes it possible to omit the oil ring. Therefore, a ring groove for an oil ring is not required, and the strength of the piston is improved, so that the piston can be thinned. In this way, it is possible to reduce the weight and improve the productivity of the internal combustion engine.

[0031] The piston ring according to the twelfth aspect is the first aspect.
It is characterized in that it is formed as a top ring with respect to any one of the constitutions (1) to (11). Since the piston ring is formed as a top ring in the compression ring as described above, when this piston ring is applied to an internal combustion engine, unburned gas or incompletely combusted gas that accumulates in the space closer to the space than the piston ring is. Or abnormal combustion of these gases is reduced, and knocking and the like can be reduced.

In any one of the first to twelfth aspects, the piston and the cylinder may be applied to an internal combustion engine by using the piston and the cylinder as an internal combustion engine piston and the high-pressure gas as a combustion gas. In the internal combustion engine, it is necessary to take measures against twisting of the piston ring due to the high-pressure combustion gas.

[0033]

[First Embodiment] FIG. 1 is a sectional view of an outer ring 2 as one embodiment of a piston ring according to the present invention.

Here, the outer ring 2 is made of resin and is formed as a seamless ring having no abutment. As the resin, for example, a relatively hard and wear-resistant resin such as polyimide is selected.

The inner peripheral surface 4 of the outer ring 2 is formed as a short cylindrical surface as a whole and is smooth.
The ridges 8 and 10 of the book are arranged over the entire circumference of the outer ring 2. At the tip of each of the ridges 8 and 10, there are formed tip surfaces 8a and 10a forming a short cylindrical outer peripheral surface, and tapered surfaces 8b and 10b at corner positions on the combustion chamber side.

Of the two ridges 8, 10, the tip surface 8a of the upper ridge 8 on the combustion chamber side is the lower ridge 1 on the crankcase side.
The width (height of the cylinder) is larger than that of the front end face 10a of the zero. In FIG. 1, the tip surface 8a of the upper ridge 8 is 1.2 to 1.2 mm of the tip surface 10a of the lower ridge 10.
It is set to three times the width. In other words, the tip surface 8a of the upper ridge 8 is also equal to the tip surface 10a of the lower ridge 10 in area.
Is set to 1.2 to 3 times.

When the outer ring 2 is in use,
As shown in FIG. 1, the inner ring 12 and the coil expander 14 are used in combination as a piston ring structure. In the first embodiment, the piston ring structure also includes a compression ring,
It is used as a second ring disposed in the second ring groove 18 from the top of the piston 16.

Here, in the ring groove 18 of the piston 16, the coil expander 14 is arranged inside, the inner ring 12 is arranged in the middle, and the outer ring 2 is arranged outside. The coil expander 14 is formed by winding a steel wire having a circular cross section or a rectangular cross section in a coil shape. A steel core 14a penetrates the coil, and the steel wire is bent circularly along the core 14a. Have been.

The inner ring 1 pressed toward the cylinder 20 by the pressing force from the coil expander 14
Numeral 2 has a substantially V-shaped groove which opens to the coil expander 14 side.
It receives the pressing force from 4. Therefore, the inner ring 12 presses the outer ring 2 adjacent on the outside toward the cylinder 20 side.

Since the inner ring 12 is formed of a relatively elastic resin, for example, polytetrafluoroethylene (PTFE), the inner ring 12 itself is inclined by the pressure of the coil expander 14. With the 12a and 12b open, they expand toward the combustion chamber and the crankcase, respectively. Therefore, the inner ring side surface 12c on the crankcase side is in close contact with the side surface 18a on the crankcase side of the ring groove 18, and the inner ring side surface 12d on the combustion chamber side is in close contact with the side surface 18b on the combustion chamber side of the ring groove 18. Thereby, the space between the side surfaces 18a and 18b of the ring groove 18 and the inner ring 12 exhibits a perfect sealing property against the combustion gas.

Further, both the inner ring 12 and the outer ring 2 are seamless rings having no abutment, and the outer ring 2 is pressed by the coil expander 14 through the inner ring 12 so that the inner peripheral surface of the cylinder 20 is pressed. 20a is in contact with the entire circumference. Therefore, the combustion gas in the combustion chamber is completely sealed.

Here, the pressing force from the coil expander 14 is applied almost at the middle of the tip surface 8a of the upper ridge 8 and the tip surface 10a of the lower ridge 10, so that the pressing force of the coil expander 14 is Are approximately equally distributed on both end surfaces 8
a, 10a. As described above, the lower ridge 1
0 is set to have a width of 1 / 1.2 to 1/3 of the area of the distal end surface 8a of the upper ridge 8, so that the distal end surface 10a of the lower ridge 10 Peripheral surface 20a
Is higher than that of the tip surface 8a of the upper ridge 8 by 1.
The pressure is 2-3 times higher.

According to the first embodiment described above, the following effects can be obtained. (I). In the outer ring 2, as described above, the width of the distal end face 10 a of the lower ridge 10 is equal to the width of the distal end face 8 of the upper ridge 8.
a formed on the inner peripheral surface 20 a of the cylinder 20 due to the pressing force of the coil expander 14,
0 a is higher than the tip end surface 8 a of the upper ridge 8.

As described in the section of the problem to be solved by the present invention, the pressure of the high-pressure combustion gas on the combustion chamber side acts on the outer ring 2 to cause the outer ring 2 to slide on the sliding surface side.
That is, it works so as to twist the tip surfaces 8a and 10a in the direction of lowering the crankcase side. However, as mentioned above,
The tip surface 8a of the upper ridge 8 that receives the high pressure of the combustion gas almost directly from the combustion chamber side has a large action than the tip surface 10a of the lower ridge 10 to maintain a stable posture. The twist of the outer ring 2 can be prevented. Therefore, the tip surface 10a of the lower ridge 10
Can be prevented from rising from the inner peripheral surface 20a of the cylinder 20 or reducing the pressure.

Further, since the pressure of the distal end surface 10a of the lower ridge 10 is higher than the pressure of the distal end surface 8a of the upper ridge 8, the adhesion to the inner peripheral surface 20a of the cylinder 20 is increased, and the engine oil is removed from the crankcase. The effect of preventing entry from the side to the combustion chamber side is enhanced.

From these facts, it is possible to sufficiently prevent the deterioration of the sealing performance. (B). Since both the outer ring 2 and the inner ring 12 do not have an abutment, the high pressure of the combustion gas is particularly likely to be applied.

(C). Further, since the outer ring 2 is formed as an outer ring-shaped member in a piston ring structure composed of a plurality of ring-shaped members, the outer ring 2 has a larger diameter than when a single ring-shaped member is used as a piston ring. Although the width in the direction is small and the torsion is likely to occur due to the pressure of the combustion gas, such a structure can also prevent the deterioration of the sealing property, and the effect is remarkable.

[Second Embodiment] In the first embodiment, an example of an outer ring provided with two ridges having different widths at the tip end surface has been described. However, the outer ring 102 made of resin according to the second embodiment has been described. In FIG. 3, there is no ridge as shown in FIG. 3, and only one sliding surface 108 is formed to be in contact with the inner peripheral surface 120a of the cylinder 120. And sliding surface 1
08, a tapered surface 110 is formed on the combustion chamber side.

Here, the V-shaped groove 1 of the inner ring 112 is used.
Reference numeral 13 is formed not on the center of the inner ring 112 but on the crankcase side. For this reason, the coil expander 114 is also biased toward the crankcase, and the pressing force E of the coil expander 114 is located closer to the crankcase than the center P of the outer ring 102, as shown in FIG. Therefore, the moment U in the opposite direction to the moment DM applied to the outer ring 102 by the pressure of the combustion gas on the combustion chamber side with respect to the outer ring 102.
M from the coil expander 114 to the inner ring 1
12 can be given.

According to the second embodiment described above, the following effects can be obtained. (I). In the expander 114 that applies a pressing force to the outer ring 102, the center position of the pressing force is closer to the crankcase side than the center P of the outer ring 102. As a result, as shown in FIG. 4, the pressure applied by the outer ring 102 to the inner peripheral surface 120a of the cylinder 120 is greater in the sliding surface 108 in the crankcase-side area DA than in the combustion chamber-side area UA. Have been higher.

As described above, since the pressing center of the coil expander 114 is biased toward the crankcase,
Not only the height of the pressure but also the total force of the pressing force is largely distributed to the crankcase side. Therefore, the pressing force of the coil expander 114 generates a moment UM in the opposite direction to cancel the torsion moment DM due to the combustion gas, and the torsion due to the combustion gas can be prevented. Further, the inner circumferential surface 1 of the cylinder 120 in a region DA of the sliding surface 108 on the crankcase side.
Adhesion with 20a is also increased, and the sealing performance can be further improved.

(B). Also, the coil expander 114
Is biased toward the crankcase side, so that the portion mainly supporting the outer ring 102 with respect to the inner peripheral surface 120a of the cylinder 120 is the same as the crankcase-side area DA within the sliding surface 108. Become. That is, since the support is supported at a position where the influence (temperature and pressure) of the combustion gas from the combustion chamber is small, the posture of the outer ring 102 is stabilized, and the sealing performance can be further ensured.

(C). The same operation and effect as (b) and (c) of the first embodiment are obtained. [Embodiment 3] Embodiment 3 is different from Embodiment 1 described above.
5 is different from the outer ring 20 as shown in FIG.
2 is that the width of the distal end surface 210a of the lower ridge 210 is larger than the distal end surface 208a of the upper ridge 208. Further, the difference from the first embodiment is that the outer diameter of the upper ridge 208 at the distal end surface 208a is smaller than that of the lower ridge 210.
0a, the tip surface 210a of the lower ridge 210 is actually smaller even during the operation of the internal combustion engine.
The cylinder 22 is pressed by the pressing force of the coil expander 214.
0 is in contact with the inner peripheral surface 220a of the
Is that the tip end surface 208a is not in contact with the inner peripheral surface 220a of the cylinder 220.

According to the third embodiment described above, the following effects can be obtained. (I). In the outer ring 202, since the diameter of the distal end surface 208a of the upper ridge 208 in the operating state of the internal combustion engine is smaller than the diameter of the distal end surface 210a of the lower ridge 210, only the distal end surface 210a of the lower ridge 210 is formed. It contacts the inner peripheral surface 220a of the cylinder 220. Accordingly, the pressing force of the coil expander 214 is entirely equal to the tip surface 2 of the lower ridge 210.
10a will receive it. As a result, the upper ridge 208
Lower ridge 210 than the pressure (= 0) of the front end surface 208a of the
Of course, the pressure on the front end surface 210a of the first member becomes higher.

Therefore, the same operation and effect as those in the first embodiment are obtained. (B). The distal end surface 208a of the upper ridge 208 is not in contact with the inner peripheral surface 220a of the cylinder 220, but the gap is very narrow, and further, the space 21 that can be expanded behind it is expanded.
Since 1 exists between the lower rib 210 and the lower ridge 210, a labyrinth effect is generated, and can play a role of preventing the leakage of the combustion gas.

(C). The width of the distal end surface 210a of the lower ridge 210 that contacts the inner peripheral surface 220a of the cylinder 220 with sufficient pressure and supports the outer ring 202 is formed larger than the distal end surface 208a of the upper ridge 208. . For this reason, the posture of the outer ring 202 is further stabilized, and more favorable sealing properties can be maintained.

(D). It has the functions and effects of (b) and (c) of the first embodiment and (b) of the second embodiment. [Fourth Embodiment] The structure of the fourth embodiment is shown in the sectional view of FIG. In the fourth embodiment, unlike the first embodiment, the outer ring 302 has three ridges 308 and 30.
9,310. These three ridges 308-31
Numeral 0 designates respective tip surfaces 308a, 309a, 310a which are in sliding contact with the inner peripheral surface 320a of the cylinder 320. The pressure applied to the inner peripheral surface 320a of the cylinder 320 by the distal end surfaces 308a to 310a is given by a coil expander 314 via an inner ring 312.

Here, in the inner ring 312,
On the coil expander 314 side, a semicircular groove 312a having a larger inner diameter than the coil expander 314 is formed. For this reason, the coil expander 314 is
The inner ring 312 is pressed toward the outer ring 302 at the center of 2a (in this case, also the center of the inner ring 312).

The inner ring 312 and the outer ring 3
02 is formed to have the same width in the axial direction of the piston 316, so that the coil expander 314 has the center of the entire width of the outer ring 302 as the pressing center F.
However, in the outer peripheral surface of the outer ring 302, an undercut region 313 in which no ridge is formed is formed on the crankcase side. Due to the presence of the undercut region 313, the leading end surfaces 3 of the ridges 308 to 310 are formed.
The distribution of 08a to 310a is biased toward the combustion chamber.

Therefore, the pressing center F is
The tip surfaces 308a-310a of 8-310
0 is shifted toward the crankcase side by a distance d with respect to the reaction force center G received from the inner peripheral surface 320a.

Note that, as shown in FIG.
Is also used as the second ring 350 in the compression ring. Therefore, a top ring 352 is provided on the outer peripheral surface of the piston 316 on the combustion chamber side, and an oil ring 354 is provided on the crankcase side.

Here, the top ring 352 is formed in a metal ring shape having an abutment. 8, the oil ring 354 includes a pair of side rails 356 and 358 and one expander 360. Each side rail 356, 358 is shown in FIG.
As shown in the perspective view of FIG.
Are formed in a metal ring shape. This 2
When the two abutments 356a and 358a are combined as an oil ring 354 and are arranged in the ring groove of the piston 316, the two abutments 356a and 358a
Are arranged with a phase difference of ° (the arrangement state of FIG. 9). The expander 360 urges the pair of side rails 356 and 358 toward the cylinder 320 by the annularly arranged protrusions 360 a present on the inner peripheral side. As a result, the outer peripheral sides of the side rails 356 and 358 are slidably in contact with the inner peripheral surface of the cylinder 320, thereby preventing the oil in the crank chamber from entering the combustion chamber.

According to the fourth embodiment described above, the following effects can be obtained. (I). Unlike the second embodiment, the pressing center F is the center of the second ring 350. Furthermore, ridges 308-
The reaction force center G received by the distal end surfaces 308a to 310a of the 310 from the inner peripheral surface 320a of the cylinder 320 is biased toward the combustion chamber. That is, the pressing center F is shifted toward the crankcase with respect to the reaction force center G.

For this reason, the pressing force of the coil expander 314 generates a moment in the opposite direction that more strongly cancels the torsional moment due to the combustion gas. Therefore,
Twisting due to combustion gas can be more strongly prevented.

Furthermore, since a particularly strong pressure acts on the ridge 310 on the crankcase side due to this moment, the effect of scraping oil adhering to the inner peripheral surface 320a of the cylinder 320 down to the crankcase side is improved, Oil sealability can be further improved.

(B). Further, the protrusions 31 on the crankcase side are formed by the two protrusions 308 and 309 on the combustion chamber side and the center.
Since the two spaces 308b and 309b are formed before 0, the action as a labyrinth is enhanced, and the role of preventing the leakage of the combustion gas can be further enhanced. Moreover, the central ridge 309 not only prevents leakage of high-pressure gas but also assists in scraping off oil. Therefore, the sealing performance can be further improved.

(C). The same operation and effect as (b) and (c) of the first embodiment are obtained. [Fifth Embodiment] FIG. 10 shows the configuration of the fifth embodiment. In the fifth embodiment, unlike the fourth embodiment,
In the second ring 450, the metal side rail 4 is provided in the ring groove 418 adjacent to the outer ring 402 and the inner ring 412 and on the crankcase side.
40 are arranged. The side rails 440 are different in size but have the same shape as the side rails 356 and 358 used for the oil ring 354 shown in FIG. 9 of the fourth embodiment. Other configurations are the same as those of the fourth embodiment.

The side rail 440 is a side rail 440
Pressure is applied to the inner peripheral surface of the cylinder 420 from the coil expander 414 via the engagement portion 412a of the inner ring 412 disposed inside the cylinder 420. Further, pressure on the inner peripheral surface of the cylinder 420 is generated by the elastic force of the side rail 440 itself.

According to the fifth embodiment described above, the following effects can be obtained. (I). The functions and effects (a) to (c) of the fourth embodiment are obtained. (B). The second ring 450 includes a side rail 440 on the crankcase side. Therefore, it is possible to more strongly prevent the oil from entering the combustion chamber. Therefore, the sealing performance can be further improved.

[Sixth Embodiment] A sixth embodiment is different from the first embodiment shown in FIG.
As shown in FIG. 1, the second ring 4 of the fifth embodiment
In a seal structure using a second ring 550 having the same configuration as 50, the oil ring and its ring groove are omitted. That is, the piston ring 516 and the cylinder 520 are sealed by two piston rings of the top ring 552 and the second ring 550. Since the second ring 550 has the same configuration as that shown in FIG. 10, it has both functions of a compression ring and an oil ring.

According to the sixth embodiment described above, the following effects can be obtained. (I). The functions and effects (a) to (c) of the fourth embodiment are obtained. (B). Even if the oil ring is omitted, the second ring 550 having the side rail 540 on the crankcase side can also serve as the oil ring, so that it is possible to prevent oil from entering the combustion chamber side and maintain the oil sealing property. Can be. Therefore, the oil ring can be omitted. Therefore, a ring groove for an oil ring is not required, and the strength of the piston 516 is improved.
6 can be made thinner. In this way, it is possible to reduce the weight and improve the productivity of the internal combustion engine.

[Seventh Embodiment] A seventh embodiment is different from the one shown in FIG.
As shown in FIG. 2, a compression ring having the same configuration as the second ring 350 of the fourth embodiment is used as the top ring 652. Also, the second ring 65
As 0, a compression ring having the same configuration as the top ring 352 of the fourth embodiment is used. That is, the fourth embodiment is different from the fourth embodiment in that the top ring and the second ring are interchanged.

According to the seventh embodiment described above, the following effects can be obtained. (I). The functions and effects (a) to (c) of the fourth embodiment are obtained. (B). The outer ring 602 constituting the top ring 652 is made of resin, and has high adhesion to the inner peripheral surface of the cylinder 620. The inner ring 612 constituting the top ring 652 is also made of resin and has high adhesion to the ring groove 618. For this reason, the unburned air-fuel mixture or incomplete combustion gas in the combustion chamber easily accumulates during the operation of the internal combustion engine up to the gap 670 above the top ring 652. Gap 672 on the crankcase side from top ring 652
Almost no unburned mixture or incompletely combusted gas reaches. That is, the clevis volume is reduced.

Therefore, in the exhaust stroke, the gap 670
Blowout of unburned air-fuel mixture and incomplete combustion gas is smaller than when the top ring is the single metal ring described in the fourth embodiment. For this reason, it is possible to suppress a decrease in the amount of intake air and a deterioration in emission due to the unburned air-fuel mixture or incomplete combustion gas.

Further, even if the unburned mixture or incomplete combustion gas in the gap 670 is adiabatically compressed due to the expansion and combustion wave of the mixture present in the combustion chamber during the explosion stroke, the unburned mixture or incomplete Since the amount of combustion gas is small, abnormal combustion such as knocking can be suppressed, and the durability of the internal combustion engine can be increased.

[Other Embodiments] In the first to seventh embodiments, examples of the outer ring and the inner ring having no joint have been described. Can be prevented.

In the first to seventh embodiments, the present invention is embodied as an outer ring used for a piston ring structure. However, the outer ring having the same shape as the outer ring of the first to seventh embodiments may be used. Alternatively, a form used in combination with a coil expander without an inner ring may be used, and a form using the same shape as the outer ring alone without the inner ring or the coil expander may be used. Even with such a structure, it is possible to prevent a decrease in sealing performance.

In the first to seventh embodiments, the tapered surface (8b, 10b, 1
10, 208b, 210b, etc.), but even if there is no tapered surface on the combustion chamber side, there is an effect of preventing a decrease in sealing performance.

In the first to sixth embodiments, an example has been described in which the second ring is used as a second ring. However, the configuration of each embodiment can be applied to a top ring existing at the top.

In the third embodiment, the upper ridge 2
08 is the inner peripheral surface 220a of the cylinder 220.
a of the lower ridge 210 but not in contact with
If the pressure does not exceed the pressure on the side, the distal end surface 208 a of the upper ridge 208 may be brought into contact with the inner peripheral surface 220 a of the cylinder 220.

In the second rings 450 and 550 of the fifth and sixth embodiments, an example is shown in which the side rails 440 and 540 are arranged on the crankcase side in the ring groove, but on the combustion chamber side in the ring groove. It may be arranged, and a similar effect is produced.

In the seventh embodiment, a steel ring having an abutment may be used as the inner ring 612 instead of the resin ring. Also in this case, the outer ring 602 is made of resin and has high adhesion to the inner peripheral surface of the cylinder 620.
The effects described above are produced.

Although the embodiments of the present invention have been described above, the embodiments of the present invention include the following various technical items in addition to the technical items described in the claims. It should be noted that it has.

(1). Two ridges projecting toward the cylinder side and having a leading end surface abutting on the inner circumferential surface of the cylinder as a sliding surface are formed over the entire circumference, and the width of the leading end surface on the space side is: The width of the ridge tip surface on the side opposite to the space is formed larger than the width, and the pressing force is applied to the ridge tip surface on the space side and the ridge tip surface on the opposite side to the space. Are distributed substantially evenly, so that the pressure is higher on the side opposite to the space than on the space side, of the sliding surfaces abutting on the inner peripheral surface of the cylinder. The piston ring according to claim 1, wherein:

(2). The pressure is given by an expander that is arranged in the ring groove and presses the piston ring against the inner circumferential surface of the cylinder, and the center of pressing of the expander is higher than the center of the sliding surface that is in contact with the inner circumferential surface of the cylinder. Also, by being biased to the opposite side to the space, the pressure is made higher on the side opposite to the space than on the space side, of the sliding surfaces abutting on the inner peripheral surface of the cylinder. The piston ring according to claim 1, wherein:

(3). The said piston and the said cylinder are a piston and a cylinder of an internal combustion engine, and the said high temperature gas is a combustion gas.
3. The piston ring according to any one of 2.

[0087]

According to the first aspect of the present invention, the pressure on the inner peripheral surface of the cylinder is such that the pressure on the inner peripheral surface of the cylinder is closer to the inner peripheral surface of the cylinder than the space side. Have been higher. The pressure of the high-pressure gas in the space acts on the piston ring to lower the sliding surface side of the piston ring to the opposite side to the space, but from the sliding surface of the piston ring to the inner circumferential surface of the cylinder. Is biased toward the opposite side to the space, a moment in the opposite direction to the torsional moment generated by the high-pressure gas is generated in the piston ring. For this reason, the moment of torsion by the high-pressure gas is weakened, and the phenomenon that the sliding surface on the opposite side to the space rises or the pressure decreases is prevented. Therefore, it is possible to prevent a decrease in sealing performance without hindering the function of scraping oil or the like to the opposite side of the space. Further, in claim 1, even when the pressure is higher on the side opposite to the space, the total force may be smaller than that on the space side. It cannot be a moment in the opposite direction to the torsional moment caused by. However, even in such a case, it is possible to prevent the sealing performance from being lowered by the following configuration.

According to a second aspect of the present invention, in the piston ring according to the first aspect, at least two projections projecting toward the cylinder and having a front end surface abutting against the inner peripheral surface of the cylinder as a sliding surface. Is formed over the entire circumference, and the width of the ridge tip surface on the opposite side to the space is formed to be smaller than the width of the ridge tip surface on the space side, so that the pressure is reduced. Among the sliding surfaces that are in contact with the inner peripheral surface of the cylinder, the side opposite to the space is higher than the side of the space. In this way, the sliding surface on the space side receiving the high pressure from the space side has a high action of maintaining a stable posture by being wider than the sliding surface on the opposite side,
Twisting due to high pressure can be prevented. As a result, the sliding surface on the opposite side can be prevented from rising from the cylinder or reducing the pressure, so that good sealing performance can be maintained. Further, even if the total pressure of the respective sliding surfaces on the space side and the opposite side is the same as the total force, the posture stability by the sliding surface on the space side becomes higher, and further, Since the sliding surface on the side opposite to the space side has a high pressure on the cylinder inner peripheral surface, the adhesion to the cylinder inner peripheral surface is increased, and the effect of preventing oil from entering the space side is high. Become. Therefore, it is possible to sufficiently prevent a decrease in sealing performance.

According to the third aspect of the present invention, the pressing center of the expander is deviated from the center of the piston ring to the side opposite to the space, so that not only the pressure but also the total pressing force is reduced. In addition, a large amount is distributed to the sliding surface opposite to the space, and twisting due to high-pressure gas can be prevented, and the adhesion to the inner peripheral surface of the cylinder is increased, and the sealing performance is further improved. can do.

According to a fourth aspect of the present invention, in the piston ring according to the third aspect, at least two ridges projecting toward the cylinder and having a front end surface abutting on the inner peripheral surface of the cylinder as a sliding surface. Are formed over the entire circumference. In this way, even with a piston ring having two or more protruding ridges as the sliding surfaces, the effects described in claim 3 can be obtained. Moreover, in this case, the distal end surface of the ridge on the space side can sufficiently prevent the leakage of high-pressure gas even if the pressure is low, and the distal end surface of the ridge on the opposite side has a high pressure. The effect of scraping off the oil can be sufficiently exhibited. In this way, each can sufficiently fulfill a role, and a labyrinth effect is also generated by the space between two or more ridges, so that the sealing performance can be further improved.

According to a fifth aspect of the present invention, in the piston ring according to the first aspect, at least two protrusions projecting toward the cylinder and having a front end surface abutting on the inner peripheral surface of the cylinder as a sliding surface. Is formed over the entire circumference, and the outer diameter of the ridge tip surface on the space side in the actual machine operation state is smaller than the outer diameter of the ridge tip surface on the side opposite to the space. , The pressure is higher on the side opposite to the space than on the space side, of the sliding surfaces abutting on the inner peripheral surface of the cylinder. Due to such a difference in the outer diameter at the ridge tip surface, the pressure on the sliding surface of the ridge on the side opposite to the space is increased, so that the effect of claim 1 can be produced. Moreover, the distal end surface of the ridge on the space side can play a role of preventing leakage of high-pressure gas even if the pressure is low or even if it does not contact the inner peripheral surface of the cylinder.
Since the tip surface of the opposite ridge has high pressure, the effect of scraping off the oil can be sufficiently exhibited. Therefore, each ridge tip surface can play its role sufficiently,
The sealing performance can be further improved.

According to a sixth aspect of the present invention, in the piston ring according to the fifth aspect, the width of the distal end face on the side opposite to the space is larger than the width of the distal end face on the space side. It is formed large. In this way, the width of the tip end surface of the ridge that is sufficiently pressed against the inner peripheral surface of the cylinder is formed to be large, and in addition to the effect of claim 5, the posture of the piston ring is stabilized, Even better sealing properties can be ensured.

In the piston ring according to the seventh aspect, no abutment is formed. As described above, the resin piston ring of the type having no abutment is particularly likely to be twisted because it is easily subjected to a high pressure. It is.

[0094] The piston ring of claim 8 is formed as an outer ring member in a piston ring structure composed of a plurality of ring members. The above-described piston ring may be used not only alone but also as a piston ring structure together with another ring-shaped member, and as described above, it is possible to prevent a decrease in sealing performance. In addition, when used in a part of the piston ring structure, the width in the radial direction is small and the torsion is likely to occur due to the pressure from the high-pressure gas. The effect is remarkable.

The piston ring according to the ninth aspect has the following features.
In the configuration according to any one of (3) to (13), three ridges projecting toward the cylinder and having a front end surface abutting on the inner peripheral surface of the cylinder as a sliding surface are formed over the entire circumference. As described above, even with the piston ring having the tip end surfaces of the three ridges as the sliding surfaces, the effects described in claims 1 to 3 can be obtained. Moreover, in this case, the distal end surface of the ridge on the space side can sufficiently prevent the leakage of high-pressure gas even if the pressure is low, and the distal end surface of the ridge on the opposite side has a high pressure. The effect of scraping off the oil can be sufficiently exhibited. Moreover, the central ridge has this intermediate function,
Assists in preventing leakage of high pressure gas and scraping action of oil. Therefore, each can play a sufficient role, and there is also a labyrinth effect due to the two spaces between the ridges, so that the sealing performance can be further improved.

The piston ring according to the tenth aspect is the first aspect.
In addition to any one of the above configurations, a side rail is provided in the ring groove adjacent to the resin piston ring on the side opposite to the space and slides with the cylinder inner peripheral surface. ing. Since the side rail is provided adjacent to the opposite side of the space as described above, the action of scraping oil by the present piston ring can be increased.

The piston ring according to the eleventh aspect is the first aspect.
In the configuration described in No. 0, the oil ring and the compression ring are also used. This makes it possible to omit the oil ring. Therefore, a ring groove for an oil ring is not required, and the strength of the piston is improved, so that the piston can be thinned. In this way, it is possible to reduce the weight and improve the productivity of the internal combustion engine.

The piston ring according to the twelfth aspect is the first aspect.
It is formed as a top ring with respect to any one of the structures of Nos. 1 to 11. By being formed as a top ring in the compression ring,
When this piston ring is applied to an internal combustion engine, the amount of unburned gas or incompletely burned gas that accumulates in the gap on the space side of the piston ring is reduced, or abnormal combustion of these gases is reduced, resulting in knocking, etc. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an outer ring according to a first embodiment.

FIG. 2 is a sectional view showing a state in which the outer ring according to the first embodiment is applied to an internal combustion engine.

FIG. 3 is a sectional view showing a state in which the outer ring according to the second embodiment is applied to an internal combustion engine.

FIG. 4 is an explanatory diagram showing a relationship between pressing forces on an outer ring according to a second embodiment.

FIG. 5 is a sectional view showing a state in which the outer ring according to the third embodiment is applied to an internal combustion engine.

FIG. 6 is a sectional view showing a state in which the outer ring according to the fourth embodiment is applied to an internal combustion engine.

FIG. 7 is a sectional view showing an arrangement state of a piston ring according to a fourth embodiment.

FIG. 8 is a perspective view showing a configuration of an oil ring according to a fourth embodiment.

FIG. 9 is a perspective view showing a configuration of a side rail used for an oil ring according to a fourth embodiment.

FIG. 10 is a sectional view showing a state in which the piston ring according to the fifth embodiment is applied to an internal combustion engine.

FIG. 11 is a sectional view showing an arrangement state of a piston ring according to a sixth embodiment.

FIG. 12 is a sectional view showing an arrangement state of a piston ring according to a seventh embodiment.

FIG. 13 is a sectional view showing a state of a conventional piston ring.

[Explanation of symbols]

2 outer ring, 4 inner peripheral surface, 6 outer surface, 8 upper ridge, 8a distal end surface, 8b, 10b taper surface, 10
... lower ridge, 10a ... tip surface, 12 ... inner ring,
12a, 12b: slope, 12c, 12d: inner ring side surface, 14: coil expander, 14a: core material, 1
6 ... piston, 18 ... ring groove, 18a, 18b ... side surface, 20 ... cylinder, 20a ... inner peripheral surface, 102 ... outer ring, 108 ... sliding surface, 108a ... combustion chamber side edge,
110 ... tapered surface, 112 ... inner ring, 11
3 ... V-shaped groove, 114 ... Coil expander, 120 ...
Cylinder, 120a: inner peripheral surface, 202: outer ring, 208: upper ridge, 208a: distal surface, 210: lower ridge, 210a: distal surface, 211: space, 214: coil expander, 220: cylinder, 220a ... inner peripheral surface, 302 ... outer ring, 308, 309, 310
... Ridge, 308a, 309a, 310a.
8b, 309b ... space, 312 ... inner ring, 31
2a: groove, 313: undercut area, 314: coil expander, 316: piston, 320: cylinder, 320a: inner peripheral surface, 350: second ring, 35
2: Top ring, 354: Oil ring, 356, 3
58 ... side rail, 356a, 358a ... joint, 36
0: Expander, 360a: Projection, 402: Outer ring, 412: Inner ring, 412a: Engagement part, 414: Coil expander, 418: Ring groove,
420 ... cylinder, 440 ... side rail, 450 ... second ring, 516 ... piston, 520 ... cylinder,
540: Side rail, 550: Second ring, 55
2 ... Top ring, 602 ... Outer ring, 612 ...
Inner ring, 618: ring groove, 620: cylinder, 650: second ring, 652: top ring,
670, 672... Gap.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Taro Ito 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yoshihiko Masuda 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation ( 72) Inventor Michio Okamoto 1-9-9 Yaesu, Chuo-ku, Tokyo Imperial Piston Ring Co., Ltd.

Claims (12)

[Claims] 1. A piston is disposed in a space defined by a piston and a cylinder by being disposed in a ring groove formed in a circumferential direction on a peripheral surface of the piston and being pressed against an inner peripheral surface of the cylinder in which the piston reciprocates. A piston ring made of resin for preventing leakage of high-pressure gas, wherein a pressure generated by the pressing is opposite to the space than the space in a sliding surface abutting on the inner peripheral surface of the cylinder. A piston ring characterized in that the piston ring is higher. At least two projections projecting toward the cylinder and having a leading end surface abutting against the inner peripheral surface of the cylinder as a sliding surface.
The ridges of the book are formed over the entire circumference, and the width of the ridge tip surface on the side opposite to the space is formed smaller than the width of the ridge tip surface on the space side, 2. The piston ring according to claim 1, wherein the pressure is higher on the side opposite to the space than on the space side, of the sliding surface abutting on the inner peripheral surface of the cylinder. 3. 3. The pressure is given by an expander which is arranged in a ring groove and presses the piston ring against the inner peripheral surface of the cylinder, and a center of pressing of the expander is opposite to the center of the piston ring in the space. By being biased to the side, the pressure is higher on the side opposite to the space than on the space side, of the sliding surface abutting on the inner peripheral surface of the cylinder. The piston ring according to claim 1, wherein: 4. At least two projections projecting toward the cylinder and having a leading end surface abutting on the inner peripheral surface of the cylinder as a sliding surface.
4. The piston ring according to claim 3, wherein the ridge is formed over the entire circumference. 5. At least two projections protruding toward the cylinder and having a leading end surface abutting on the inner peripheral surface of the cylinder as a sliding surface.
While the projecting ridge is formed over the entire circumference, the outer diameter of the projecting ridge on the space side in the actual machine operation state is larger than the outer diameter of the projecting ridge on the side opposite to the space. Is formed to be smaller, the pressure is
2. The piston ring according to claim 1, wherein, of the sliding surfaces abutting on the inner peripheral surface of the cylinder, a side opposite to the space is higher than a side of the space. 3. 6. The piston according to claim 5, wherein the width of the ridge tip surface on the side opposite to the space is formed larger than the width of the ridge tip surface on the space side. ring. 7. The piston ring according to claim 1, wherein an abutment is not formed. 8. The piston ring according to claim 1, wherein the piston ring is formed as an outer ring member in a piston ring structure composed of a plurality of ring members. 9. A projection formed on the entire circumference of the cylinder, wherein three projections projecting toward the cylinder and having a front end surface abutting against the inner peripheral surface of the cylinder as a sliding surface are formed.
3. The piston ring according to any one of 3. 10. A cylinder inner peripheral surface which is arranged in a ring groove adjacent to a side opposite to said space with respect to said resin piston ring in a ring groove. A piston ring comprising a side rail that slides with the piston ring. 11. The piston ring according to claim 10, wherein the piston ring doubles as an oil ring and a compression ring. 12. The piston ring according to claim 1, wherein the piston ring is formed as a top ring.