JPH09196171A - Piston ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the strength and the durability without increasing the weight of a piston ring, and to shift the resonance number of revolution of the radial motion of the piston ring outside the practical running range by setting the natural frequency in the radial direction to a higher value. SOLUTION: This thickness T in the radial direction of a piston ring 1 having a gap part 2 becomes smaller toward the gap part 2, and gradually larger farther away from the gap part 2, and approximately maximum at the opposite side 3 of the gap part 2. Thus, the weight of the piston ring 1 is not increased. The bending stress σ is small at the opposite side to the gap part 2, and becomes larger toward the gap part 2, and becomes uniform as the whole of the bending stress. Because the maximum value of the bending stress is reduced, the strength and the durability of the piston ring can be improved.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a diesel engine,
The present invention relates to a piston ring of an internal combustion engine such as a gasoline engine and a gas engine.

[0002]

2. Description of the Related Art In a conventional internal combustion engine, as shown in FIG.
23 are provided, and piston rings 24, 25 and 26 are fitted in these ring grooves. 2 in the top
The piston rings 24 and 25 of the book are called pressure rings and prevent leakage of air-fuel mixture and explosive gas in the cylinder and exhaust gas to the lower side of the piston 20, and the lower piston ring 26 is called an oil ring. Scrap off the oil that remains in the. The two pressure rings 24 and 25 are used to prevent the gas leaking from the gap between the rings in a two-stage manner.

As shown in FIG. 13, each of the pressure rings 24 and 25 has an annular ring shape, and is provided with a mating portion 27 in consideration of its assembly to the piston 20 and thermal expansion. . Generally, the shapes of the pressure rings 24 and 25 are represented by an outer peripheral radius R, a radial ring thickness T, and a ring width B. FIG. 14 shows a piston 20 and a piston ring 24,
It shows a state in which 25 and 26 are incorporated in the body of the internal combustion engine. The piston 20 having the piston rings 24, 25 and 26 assembled therein is fitted in the cylindrical bore 28 of the internal combustion engine body, and reciprocates in the cylindrical bore 28 during operation of the engine. Further, the cylindrical bore 28 does not have an accurate cylindrical shape due to accuracy in manufacturing the bore, tightening of head bolts, thermal deformation, load deformation, wear, etc., and the inner surface of the cylindrical bore 28 has a deformed portion. 30 has occurred. When the piston 20 reciprocates in the deformed portion 30 inside the cylindrical bore 28, as shown in FIG.
Due to the change in the inner diameter of the cylindrical bore 28, the pressure ring 2
A force F acts to increase or decrease the gap 27 between the mating holes 4 and 25.

FIG. 16 is a diagram showing the distribution of moments when a force F acts on the abutment portion 27 of the pressure ring, and FIG. 16 (a) shows a bending moment (M) acting on the pressure ring. FIG. 16B is a distribution chart in the case where bending stress (σ) acts on the pressure ring.
The distribution of the bending moment (M) acting on the pressure ring becomes maximum in the direction 31 opposite to the abutment portion 27. The conventional pressure ring has a radial ring thickness T dimension and a ring width B.
The dimensions are constant, and the cross-sectional area and cross-section modulus of the pressure ring are constant. The bending stress (σ) acting on the pressure ring is expressed by σ = M / Z, where Z is the ring section coefficient, and therefore the distribution of the bending stress (σ) is as shown in FIG.
As shown in (b), like the distribution of the bending moment (M), it becomes maximum in the direction 31 opposite to the abutment portion 27. The magnitude of the bending stress (σ) is a factor that determines the strength and durability of the pressure ring. In the conventional pressure ring, the opposite direction 31 of the abutment portion 27 where the bending stress is maximum is weakest and damaged. It will be easy to do. Therefore, in order to increase the strength and durability of the pressure ring, it is effective to set the ring width B dimension and the radial ring thickness T dimension to large values.

[0005]

However, when the ring width B and the radial ring thickness T are increased, the weight of the pressure ring increases and the pressure ring moves up and down in the ring groove of the piston, a so-called phenomenon. , New problems such as fluttering phenomenon occur. Further, as shown in FIG. 14, when the piston 20 reciprocates in the deforming portion 30 in the circular bore 28, the pressure rings 24 and 25 undergo radial movement in which the gap of the mating portion 27 changes ( (See FIG. 17). At this time, the radial movement cycle of the pressure rings 24 and 25 is twice as long as the reciprocating movement cycle of the internal combustion engine. And the engine is usually 600 rpm to 8000 rpm
Used at revolutions per minute, the period of radial movement of the pressure ring changes accordingly. When the radial motion cycle of the pressure ring is close to the natural radial frequency of the pressure ring, resonance occurs in the radial motion of the pressure ring and the amplitude of the radial motion of the pressure ring increases, so that the pressure ring has a cylindrical bore. The phenomenon of leaving the peripheral surface occurs. By the way, the piston ring has (1) a function of sealing high-pressure gas in the combustion chamber of the engine, (2) a function of scraping off the lubricating oil adhering to the inner wall surface of the cylindrical bore, and (3) an oil pan of the engine. It has three functions, that is, a function to prevent the lubricating oil from entering the combustion chamber. However, when the piston ring separates from the inner peripheral surface of the cylindrical bore, these three functions decrease and increase in blow-by gas, etc. This causes problems of deterioration of engine performance and increase of oil consumption.

On the other hand, in order to maintain the airtightness and reduce the oil consumption, the piston ring members are closely attached and wound about one and a half times, and both end surfaces are parallel to each other.
Moreover, a piston ring in which the outer peripheral surface is formed at right angles to both end surfaces is described in JP-A-5-223171. However, this piston ring also has problems in manufacturing, strength and durability.

The present invention was created in view of the above problems, and an object of the present invention is to improve the strength and durability of the piston ring without increasing the weight of the piston ring. In addition, by setting the radial natural frequency of the piston ring to a high value, it is possible to provide a piston ring in which the resonance rotational frequency of the radial motion of the piston ring is outside the practical operating range.

[0008]

In order to solve the above-mentioned problems, the means described in claim 1 can be adopted. According to this means, since the radial thickness of the piston ring is variable, the weight of the piston ring is not increased. Further, the bending stress is small on the opposite side of the abutment portion and becomes large in the vicinity of the abutment portion, and becomes uniform as a whole bending stress. Therefore, the maximum value of bending stress is reduced, so that the strength and durability of the piston ring can be improved.
Further, since the radial natural frequency of the piston ring can be set high, the resonance frequency can be set higher than the practical rotation range of the engine. Further, in order to solve the above-mentioned problems, the means described in claim 2 can be adopted.
According to this means, since the axial width of the piston ring is variable, the weight of the piston ring is not increased. In addition, the bending stress is small on the opposite side of the gap,
It becomes larger in the vicinity of the abutment, and the bending stress becomes uniform as a whole. Therefore, the maximum value of bending stress is reduced, so that the strength and durability of the piston ring can be improved. Further, since the radial natural frequency of the piston ring can be set high, the resonance frequency can be set higher than the practical rotation range of the engine.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a piston ring according to the present invention will be described with reference to FIGS. 1 and 2A and 2B. In the figure, the radial thickness T of the piston ring 1 having the abutment portion 2 is thin near the abutment portion 2, gradually increases as it moves away from the abutment portion 2, and is almost maximum on the opposite side 3 of the abutment portion 2. Has become. Therefore, as shown in FIG. 2A, when the force F acts on the mating portion 2, the bending moment (M) becomes maximum in the opposite direction 3 of the mating portion 2 as in the conventional piston ring. , The cross-sectional area, and the cross-section coefficient Z are smaller in the vicinity of the abutment portion 2 and larger in the opposite direction 3 of the abutment portion 2, so that the bending stress (σ) is the same as that of the conventional piston ring as shown in FIG. On the other hand, the opposite side 3 of the abutment portion 2 is small, becomes larger in the vicinity of the abutment portion 2, and the bending stress (σ) becomes uniform as a whole. With this configuration, the maximum value of the bending stress (σ) is reduced, so that the strength and durability of the piston ring can be improved.

As described above, in this embodiment, although the radial thickness T in the opposite direction 3 of the mating portion 2 is large, the vicinity of the mating portion 2 is small, so that the weight of the piston ring 1 is reduced. Piston ring 1 without increasing
Not only can the strength and durability of the piston ring 1 be improved, but the radial natural frequency of the piston ring 1 can be set to a high value. It is possible to prevent an increase in blow-by gas and an increase in oil consumption due to the separation of the inner peripheral surface of the circumferential bore.

When the piston 5 fitted with the piston ring 1 of this embodiment is mounted on the engine body 6, as shown in FIG. 3, the gap between the piston ring groove 7 and the piston ring 1 is offset, but Since the outer circumferential surface of the ring 1 is in contact with the circumferential surface of the circumferential bore 8 of the engine body 6, the three functions of the piston ring described above are not deteriorated and this is not a serious problem.

However, with respect to the deviation of the clearance, as shown in FIGS. 4A and 4B, a backup ring 10 for assisting the deviation of the clearance is disposed inside the mating portion 2 for use. Or (backup ring method),
As shown in FIGS. 5 (a) and 5 (b), by simply increasing the size of the piston ring width T'in the vicinity of the fitting portion 2 to form the fitting portion 11 (fitting method), Can be resolved.

FIG. 6 shows a second embodiment of the present invention. In the first embodiment shown in FIG.
The radial thickness T of the piston ring 1 is made thinner in the vicinity of the mating portion 2 and thicker in the opposite direction 3 of the mating portion 2, but in the second embodiment, the axial width B of the piston ring is set to be the mating portion. The width is narrower in the vicinity of 2, and gradually widens as it moves away from the abutment portion 2, and is almost maximum in the direction 3 opposite to the abutment portion 2. Therefore, as shown in FIG. 7A, when the force F acts on the mating portion 2, the bending moment (M) becomes maximum in the opposite direction 3 of the mating portion 2 as in the conventional piston ring. , The cross-sectional area, and the cross-section coefficient Z are smaller in the vicinity of the abutment portion 2 and larger in the opposite direction 3 of the abutment portion 2, so that the bending stress (σ) is the same as that of the conventional piston ring as shown in FIG. 7B. In comparison, the opposite direction 3 of the abutment portion 2 is small, increases in the vicinity of the abutment portion 2, and becomes uniform as a whole bending stress (σ). With this configuration, the maximum value of the bending stress (σ) is reduced, so that the strength and durability of the piston ring can be improved.

As described above, in the present embodiment, the width B of the piston ring in the direction 3 opposite to the mating portion 2 is large, but the vicinity of the mating portion 2 is small.
Without increasing the weight of the piston ring 1, problems such as fluttering will not occur. Further, due to the increase in bending rigidity due to the large axial width B of the piston ring in the opposite direction 3 of the abutment portion 2 and the reduction in the weight of the abutment portion 2 due to the small width B dimension of the abutment portion 2, The radial natural frequency of the piston ring can be increased. As a result, the rotational speed of the internal combustion engine at which resonance of the radial radial motion is generated can be set to a high rotational speed outside the practical range. Therefore, increase in blow-by gas due to separation of the inner peripheral surface of the circumferential bore of the engine of the piston ring 1 It is possible to prevent an increase in oil consumption.

When the piston 5 fitted with the piston ring 1 of the present embodiment is mounted on the engine body 6, as shown in FIG. 8, there is a deviation in the axial gap between the piston ring groove 7 and the piston ring 1. Although generated, since the outer peripheral surface of the piston ring 1 is in contact with the inner peripheral surface of the circumferential bore 8 of the engine body 6, the three functions of the piston ring described above are not deteriorated and it is not a serious problem.

However, with respect to the deviation of the axial gap, as shown in FIGS. 9A and 9B, the backup ring 12 for assisting the deviation of the axial gap.
May be overlaid on the abutment portion 2 side (backup ring system), or as shown in FIGS.
The problem can be easily solved by increasing only the axial width B ′ of the piston ring in the vicinity to form the fitting portion 13 (abutment fitting method).

FIG. 11 shows a third embodiment of the present invention. In the first embodiment, the radial thickness T dimension of the piston ring 1 is changed, and in the second embodiment, the axial width B dimension of the piston ring 1 is changed. In the configuration, both the radial thickness T dimension of the piston ring 1 and the axial width B dimension are changed. It goes without saying that the object of the present invention can also be achieved by such a configuration.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a piston ring of the present invention.

FIG. 2 is a distribution diagram of bending moment and bending stress of the first embodiment of the piston ring of the present invention, FIG. 2 (a) is a distribution diagram of bending moment, and FIG. 2 (b) is a distribution diagram of bending stress. Is shown.

FIG. 3 is a state diagram in which the first embodiment is mounted on an engine body.

FIG. 4 is an explanatory view of an example for assisting the first embodiment, FIG. 4 (a) is a plan view thereof, and FIG. 4 (b) is an example of the engine body of FIG. 4 (a). FIG.

5A and 5B are explanatory diagrams of another example for assisting the first embodiment, FIG. 5A is a plan view of the example, and FIG. 5B is an example of the example of FIG. It is the state figure attached to the main body.

FIG. 6 is a perspective view showing a second embodiment of the piston ring of the present invention.

FIG. 7 is a distribution diagram of a bending moment and a bending stress of a second embodiment of the piston ring of the present invention, FIG. 7 (a) is a distribution diagram of the bending moment, and FIG. 7 (b) is a distribution diagram of the bending stress. FIG. 7 (c) is a side view of the piston ring of this embodiment.

FIG. 8 is a state diagram in which the second embodiment is mounted on an engine body.

FIG. 9 is an explanatory diagram of an example for assisting the second embodiment, FIG. 9 (a) is an exploded perspective view thereof, and FIG. 9 (b).
FIG. 10 is a state diagram in which the embodiment of FIG. 9 (a) is attached to the engine body.

FIG. 10 is an explanatory diagram of another example for assisting the second embodiment, FIG. 10A is a perspective view thereof, and FIG.
10B is a state diagram in which the embodiment of FIG. 10A is mounted on the engine body.

FIG. 11 is a perspective view showing a third embodiment of the piston ring of the present invention.

FIG. 12 is a front view showing a piston of a conventional internal combustion engine, FIG. 12 (a) is a plan view of a piston in which a piston ring is not fitted, and FIG. 12 (b) is a piston in which a piston ring is fitted. FIG.

FIG. 13 is a diagram illustrating a conventional piston ring,
13 (a) is a plan view of the piston ring, FIG. 13 (b).
FIG. 4 is a side view of a piston ring.

FIG. 14 is a diagram showing a state in which a piston fitted with a piston ring is incorporated in the internal combustion engine body.

FIG. 15 is a perspective view showing a conventional piston ring.

16A and 16B are distribution diagrams of a conventional piston ring bending moment and bending stress. FIG. 16A shows a bending moment distribution diagram and FIG. 16B shows a bending stress distribution diagram.

FIG. 17 is an explanatory diagram showing an operating state of a conventional piston ring.

[Explanation of symbols]

 1 ... Piston ring 2 ... Abutment part 3 ... Opposite side of abutment part 7 ... Piston ring groove 10, 12 ... Backup ring 11, 13 ... Fitting part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Morino 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute (72) Inventor Takao Suzuki 1-cho, Toyota-cho, Aichi Prefecture Toyota Auto Car Co., Ltd. (72) Inventor Asami Tsuchiya 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Masanori Takai 1 Toyota Town, Toyota City, Aichi Toyota Motor Co., Ltd.

Claims (7)

[Claims] 1. A piston ring having an abutment portion, wherein the radial thickness of the piston ring is thinner in the vicinity of the abutment portion and gradually increases as the distance from the abutment portion increases. The piston ring is characterized in that the radial thickness on the opposite side of the part is maximum. 2. A piston ring having an abutment portion, wherein the axial width of the piston ring is narrower in the vicinity of the abutment portion and gradually widens as the distance from the abutment portion increases. The piston ring is characterized in that the axial width on the opposite side of is maximum. 3. The axial width of the piston ring is narrower in the vicinity of the mating portion and gradually widens as it moves away from the mating portion, and the axial width on the opposite side of the mating portion is The piston ring according to claim 1, wherein the piston ring has the maximum size. 4. A backup ring is arranged on the inner peripheral side of the mating portion to assist in offsetting the radial gap between the piston ring and the piston ring groove. Alternatively, the piston ring according to claim 3. 5. The piston ring according to claim 1 or 3, wherein a fitting portion having a large radial thickness is formed in the vicinity of the mating portion of the piston ring. 6. The backup ring for assisting the deviation of the axial gap between the piston ring and the piston ring groove is arranged on the side of the mating portion. The piston ring described in 3. 7. The piston ring according to claim 2 or 3, wherein a fitting portion is formed in the vicinity of the mating portion of the piston ring with an increased axial width dimension.