JP2002013638A - Piston ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston ring of an internal combustion engine, capable of ensuring both gas sealability and oil controllability. SOLUTION: This piston ring is composed of an L-shaped ring body, an expander for applying the tensile force to the ring body, and a seal ring, with a ratio h2/h1 of a height h2 from the lower face of the ring body to the angular part inside of the ring body and a ring width h1 being 1/3 or larger and 1/2 or smaller, the seal ring is mounted tightly on a part between the angular part inside of the ring body and an inclined face of a ring groove opposite to the angular part, and the thickness of the ring at a lower part of the ring body is two times or more of the clearance between an outer peripheral face of a land, formed on the lower part of the ring groove and a cylinder wall face, and 1.5 times or smaller of the ring width.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston ring used for a piston device of an internal combustion engine, and more particularly to a piston ring suitable for a single-ring piston device.

[0002]

2. Description of the Related Art Conventional pistons of a four-stroke engine generally use pistons 100 and 200 as exemplified in the main part longitudinal sectional views of FIGS. As shown in FIG. 4, a piston 100 having three ring grooves having three ring grooves has a top ring groove 1, a second ring groove 2,
Oil ring grooves 3 are provided on the outer periphery of the piston head in order from the top of the piston. In these three ring grooves,
A top ring, a second ring, and an oil ring (not shown) are respectively mounted. On the outer periphery of the piston head of the piston 100, a top land 4, a second land 5, and a third land 6 are formed in this order from the top of the piston.

As shown in FIG. 5, a two-ring type piston 200 having two ring grooves is provided with a top ring groove 1 and an oil ring groove 3 on the outer periphery of the piston head in this order from the top of the piston. And a top ring and an oil ring (not shown) are attached. The piston 200 is provided with a top land 4 and a second land 5.

Reference numeral 8 denotes a skirt portion, 9 denotes a piston top surface, and 107 and 207 denote oil escape holes penetrating from the outer peripheral portion of the piston to the inside of the piston. The main function of the piston ring mounted on the piston differs depending on the arrangement from the top of the piston. The main role of the top ring and second ring is to prevent combustion gas leakage and heat transfer,
Prevention of combustion gas leakage is achieved by a gas seal between the outer peripheral surface of the ring and the cylinder wall surface by the piston ring and a gas seal between the lower surface of the ring and the lower surface of the ring groove.

[0005] The main role of the oil ring is to appropriately control the amount of lubricating oil between the outer peripheral surface of the piston and the wall surface of the cylinder. As can be seen by comparing FIGS. 4 and 5, a two-ring piston having two ring grooves is used.
In the case of 100, since the second ring is not mounted, in order to supplement the role of the second ring, each ring of the two-ring configuration is required to have higher accuracy than each ring of the three-ring configuration.

In the meantime, the piston having the two-ring configuration shown in FIG. 5 has one less piston ring than the piston having the three-ring configuration, so that the friction loss due to the sliding resistance of the piston ring can be reduced. There is. Also,
The piston having the two-ring configuration shown in FIG. 5 has one less piston ring than the piston ring having the three configuration. Therefore, the land between the ring grooves is small, and the distance between the piston top surface and the skirt portion 8 can be shortened. If the mass of the piston head between them becomes light, the friction loss around the crank can be reduced.

In a piston device for an internal combustion engine, if only one piston ring can be used, there is a possibility that fuel efficiency can be improved by reducing friction loss due to sliding resistance of the piston ring and friction loss by reducing the weight of the piston. Is required to satisfy both the gas sealing performance and the oil control performance with only one piston ring.

[0008] For example, a piston device having a single ring configuration is disclosed in Japanese Patent Application Laid-Open No. H6-147005. JP 6-14
As shown in FIG. 6, a piston device proposed in Japanese Patent Publication No. 7005 discloses a method in which one top ring groove 1 is provided on an outer peripheral portion of a head of a piston 300 and an oil is provided between a second land 5 and a skirt portion 8 therebelow. A reservoir groove 301 is provided, and an oil escape hole 307 penetrating from the outer peripheral portion to the inside is formed in the piston 30.
0 Provided on the head, the piston ring 302
Is mounted in the cylinder.

However, the piston ring used in the piston device described in JP-A-6-147005 is
Since the piston ring is in contact with the cylinder wall surface at two locations on the upper and lower sides of the outer peripheral surface, if the tension on the cylinder wall surface is made substantially equal to the tension of the oil ring having the three ring structure, the piston device having the three ring structure However, there is a problem that the consumption of lubricating oil is increased as compared with the prior art, and it is impossible to achieve both gas sealing performance and oil control performance.

[0010]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a piston ring of an internal combustion engine capable of achieving both gas sealing performance and oil control performance. It is in.

[0011]

In order to reduce the pressing force of the combustion gas against the cylinder due to the back pressure of the combustion gas, the present inventors have used an L-shaped piston ring as the only piston ring. The present invention has been found that the gas sealing performance can be maintained by adding a sealing function to the portion, and the oil film thickness of the lubricating oil between the outer peripheral surface of the piston ring and the cylinder wall surface can be reduced when the piston descends. Was completed.

According to the present invention, there is provided a refill provided on a piston of an internal combustion engine.
A piston ring mounted in a piston groove, wherein the piston
An L-shaped ring body and tension applied to the ring body
An expander to be provided, and a seal ring,
From the lower surface of the ring body to the inner corner of the ring body
Height h_TwoAnd the ring width h of the ring body₁Ratio h _Two
/ H₁Between 1/3 and 1/2
Side corner, and an inclined surface of the ring groove facing the corner.
A seal ring is provided in close contact between the
Adjust the thickness of the lower ring to the
More than twice the distance between the outer peripheral surface of the
It is characterized by being 1.5 times or less the ring width of the ring body
It is a piston ring.

[0013] Further, the piston ring preferably has an outer peripheral surface of the ring main body that widens toward a lower portion of the ring main body.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, a case where the piston ring of the present invention is applied to a piston device having a single ring will be described in detail with reference to FIGS. FIG. 1 is a sectional view of a main part of a piston device having a single ring using a piston ring according to the present invention. FIG. 2 is a longitudinal sectional view of a main part showing a mounted state of the piston ring of the present invention. FIG. 3 is a longitudinal sectional view of an essential part for explaining the operation of the piston ring of the present invention.

In FIG. 1, 1 is a top ring groove, 11 is an oil sump groove, 4 is a top land, 5 is a second land, 8 is a skirt portion, 9 is a piston top surface, and 10 is a piston. Also, 17 is an oil escape hole, 21 is a cylinder wall surface,
22 is a piston ring. In FIG. 2, 22A is a ring main body, 22A1 is a lower part of the ring main body, and 22A2 is an upper part of the ring main body. 22B is an expander, and FIG. 2 shows an example of a coil expander, but may be a plate expander. 22C is a seal ring. Also, P is (also referred to as a ₁ dimensional) gas pressure, a ₁ the lower part of the ring thickness, the height of H is the groove width, h ₁ is the ring width, h ₂ from the lower surface of the ring body to the corner portion of the ring body , G is the distance between the outer peripheral surface of the second land 5 and the cylinder wall surface 21, C is the contact width between the outer peripheral surface of the ring main body 22A and the cylinder wall surface 21, and S is the ring main body 22A which is in close contact with the lower surface of the top ring groove 1. Is the length of the lower surface in the radial direction.

In FIG. 3, L is a lubricating oil. 2 and 3, the same components as those in FIG. 1 are denoted by the same reference numerals. As shown in FIG. 1, the piston device to which the present invention is applied has a single annular top ring groove 1 on the outer periphery of the piston 10 head, and a top ring The land 4 is formed, and the top ring groove 1 is formed.
The second land 5 is formed at the lower part of. One annular oil sump groove 11 is provided between the second land 5 and the skirt portion 8, and the oil escape hole 17 is provided so as to penetrate from the upper end of the bottom of the oil sump groove 11 to the inner surface of the piston.

The piston ring 22 of the invention is shown in FIG.
Is mounted in the top ring groove 1 of an irregular shape shown in FIG. In addition, 9 is a piston top surface. As shown in FIG. 2, the piston ring 22 of the present invention includes a ring main body 22A, a coil expander 22B, and a seal ring 22C.

The ring main body 22A is a ring having an abutment having a substantially L-shaped cross section, and has a thick lower rectangular section 22.
It is composed of A1 and a thin upper section 22A2 having a rectangular cross section. beneath
On the inner peripheral surface of 22A1, a concave portion having a circular cross section is provided along the circumferential direction. The outer peripheral surface of the ring body 22A is
It has a tapered shape that expands from 22A2 toward the lower portion 22A1.

The material of the ring body 22A may be gray cast iron, ductile cast iron, steel, heat-resistant resin or a combination thereof. The coil expander 22B is an annular coil spring.
Since only A is insufficient in tension, the tension is applied to the ring main body 22A. The tension of the ring body 22A is
It can be equivalent to the tension in an oil ring having a three-ring configuration. As the material of the coil expander 22B, a hard steel wire, a piano wire, a spring wire, or the like can be used.

As shown in FIG. 2, the piston ring 22 of the present invention has the rectangular cutout portion of the ring main body 22A inside and the coil expander 22B in the concave portion of the lower portion 22A1.
Is inserted into the top ring groove 1. At this time, the seal ring 22C is provided in close contact with a corner inside the ring main body 22A and an inclined surface of the top ring groove 1 facing the corner.

As the material of the rigid body of the seal ring 22C, steel, other metal, plastic or rubber is used, and as the material of the elastic body of the seal ring 22C, rubber or the like having a large elastic deformation capacity is used. be able to. The seal link seals between the inner corner of the ring main body 22A and the inclined surface of the top ring groove 1 facing the corner so that the combustion gas does not pass through the seal link. In the case where there is an abutment, mounting is performed so that gas does not flow at the abutment, and when sealing with an elastic seal ring 22C, a continuous ring-shaped one without an abutment is mounted.

In the piston ring 22 of the present invention, the gas is sealed at the inner corner of the ring main body 22A so as not to allow gas to pass therethrough. Even when the gas pressure P propagates from the gap between the wall surface 21 and the piston head, as shown in FIG. 2, the gas pressure P propagates from the upper surface of the upper portion 22A2 of the ring main body 22A to the inner peripheral surface and the rear surface. The lower part 22 of the ring body 22A is up to the gap between the peripheral surfaces of the opposing top ring grooves 1.
It does not reach the gap between the inner peripheral surface of A1 and the bottom surface of the top ring groove 1 facing the inner peripheral surface.

Therefore, the pressing force against the cylinder wall due to the back pressure of the combustion gas in the piston ring 22 of the present invention is reduced by (h ₂ × P) per unit circumferential length, and is smaller than that in the case where no seal ring is provided. ₂ / h _{1 is} reduced. Incidentally, h ₁ is the ring width, h ₂ is the height from the lower surface of the ring body to the corner portion of the ring body. In the piston ring 22 of the present invention, the ratio h ₂ / h of the height h ₂ from the lower surface of the ring body to the corner of the ring body and the ring width h _{1.
1 is set} to 1/3 or more and 1/2 or less.

The reason is that the ratio h ₂ / h of the height h ₂ from the lower surface of the ring main body to the corner of the ring main body and the ring width h _1.
If h ₁ is less than 1/3, the effect of reducing the pressing force against the cylinder wall due to the back pressure of the combustion gas is insufficient, and the outer peripheral surface of the piston ring 22 is pressed against the cylinder wall surface by the back pressure of the combustion gas. This is because it has been found that the oil film of the lubricating oil between the outer peripheral surface of the piston ring 22 and the cylinder wall surface is broken, and seizure occurs between both surfaces.

On the other hand, the ratio h ₂ / h ₁ between the height h ₂ and ring width h ₁ from the lower surface of the ring body to the corner portion of the ring body 1
It is found that if the ratio exceeds / 2, the gas sealing property between the cylinder wall surfaces 21 of the ring main body 22A becomes insufficient. Further, the ring body 22A of the piston ring 22 of the present invention
Is more than twice the distance g between the outer peripheral surface and the cylinder wall 21 of the second land 5 at the bottom of the ring thickness a ₁ shown in FIG. 2, there as more than 1.5 times the ring width h ₁ of the ring body 22A.

The reason for this is that the lower ring
Thickness a₁The outer peripheral surface of the second land 5 and the cylinder wall surface
If less than twice the distance g from 21, the lower ring thickness
A ₁Of the top ring groove 1
Between the lower surface of the ring body 22A and the lower surface of the top ring groove 1.
Gas sealing performance becomes insufficient, while the ring body 22A
Ring thickness a at the bottom of₁Is the ring width h₁More than 1.5 times
The rigidity of the ring body 22A increases.
Poor followability of the ring body 22A to the cylinder wall 21
Between the outer peripheral surface of the ring body 22A and the cylinder wall 21.
This is because it was found that the sealability was insufficient.

If the sealing performance between the lower surface of the ring body 22A and the lower surface of the top ring groove 1 is deteriorated, gas leaks and the thermal efficiency is reduced, and the sealing performance between the outer peripheral surface of the ring body 22A and the cylinder wall 21 is reduced. When the oil quality deteriorates, the combustion gas blows through the gap between the two surfaces, thereby destroying the oil film necessary for lubrication between the two surfaces, causing seizure and abnormal wear of the two, and making it unusable as an internal combustion engine.

Therefore, in the piston ring 22 of the present invention,
In consideration of the piston behavior, the lower ring thickness a _{1 is set} to 2 which is the distance g between the outer peripheral surface of the second land 5 and the cylinder wall surface 21.
More than doubled, by less 1.5 times the ring width h ₁ of the ring body 22A, to reduce the flexural rigidity of the ring body 22A, always contact more than half of the lower ring thickness a ₁ on the lower surface of the top ring groove 1 As a result, it was possible to follow the cylinder wall surface 21 with a low tension, thereby ensuring the gas sealing property.

The tension of the ring main body 22A can be equivalent to the tension of an oil ring having a three-ring structure. The outer peripheral surface of the ring main body 22A in the piston ring 22 of the present invention is, as shown in FIG.
A is expanded toward the lower part 22A2 of A
And at the lower portion 22A2 of the ring main body 22A.

The extension of the outer peripheral portion of the ring main body 22A toward the lower portion 22A2 of the ring main body 22A can be set to 30 'to 5 °, and the contact width C can be determined to be 0.1 to 0.2 mm. it can. Therefore, the piston ring 22 of the present invention
When the tension of the ring main body 22A is equivalent to the tension of the oil ring in a piston device having a three-ring structure, the contact surface pressure between the outer peripheral surface of the piston ring and the wall surface of the cylinder is reduced by an oil device having a three-ring structure. It can be higher than the contact surface pressure at the ring.

Here, the piston ring 22 of the present invention is used.
The ring body 22A of the
It is desirable to perform the D treatment because the contact width C can be kept constant for a long time. Next, the operation of the piston device equipped with the piston ring 22 of the present invention will be described with reference to FIG.

FIG. 3 shows a process in which the piston device is lowered when the piston device is assembled in the cylinder and reciprocated up and down. In this piston device, the only piston ring 22 is mounted on the top ring groove 1 and the oil escape hole 17 is provided at the upper end of the oil reservoir groove 11, so that when the piston device descends, the piston ring 22
While scraping off the excess lubricating oil L on the cylinder wall 21 with
As shown in FIG. 3, the lubricating oil L can escape from the oil escape hole 17 into the piston.

Excess lubricating oil L released into the piston
Is returned to the oil pan in the crankcase. The lubricating oil returned to the oil pan rises from below the skirt portion 8 in the process of ascending the piston device, accumulates in the oil sump groove 11 while lubricating the cylinder wall surface 21, and at the lower end of the piston ring 22 due to inertia. As a result, the surplus lubricating oil L is discharged from the oil escape hole 17 into the piston.

Since the oil escape hole 17 is provided at the upper end of the oil reservoir groove 11, the space between the piston outer peripheral surface below the piston ring 22 and the cylinder wall surface 21 is not filled with the lubricating oil L, and the air gap is reduced. Can be present. Therefore, even when the pressure above the piston ring 22 becomes negative,
Excess lubricating oil L does not cross the piston ring 22.

The oil reservoir groove 11 has an upper end perpendicular to the cylinder wall surface 21 and a lower portion inclined downward toward the cylinder wall surface 21. The lubrication oil accumulated in the oil sump groove 11 can be easily moved downward. At this time, in the piston device to which the present invention is applied, the ring body 22
The ratio h ₂ / h ₁ of the height h ₂ from the lower surface of A to the corner of the ring body 22A and the ring width h ₁ is set to 1/3 or more and 1/2 or less, and the ratio of the combustion gas to the cylinder due to the back pressure is increased. Since the pressing force is reduced, the oil film of the lubricating oil between the outer peripheral surface of the piston ring 22 and the cylinder wall surface is not broken.

In the piston device to which the present invention is applied, the ring thickness a ₁ of the lower part of the ring main body 22 A of the piston ring 22 is adjusted by the outer peripheral surface of the second land 5 and the cylinder wall surface 21.
The ring width h _{1 of the} ring body 22A is at least twice the distance g
1.5 times or less, the bending rigidity of the ring body 22A is reduced, more than 1/2 of the lower ring thickness a _{1 is} always in close contact with the lower surface of the top ring groove 1, and it is possible to follow the cylinder wall 21 with low tension. As a result, the sealing property is good.

Further, in the piston device to which the present invention is applied, the outer peripheral portion of the ring main body 22A of the piston ring 22 includes:
The lower end 22A2 of the ring main body 22A is widened toward the lower end 22A2 of the ring main body 22A, so that the contact surface pressure between the outer peripheral portion of the piston ring and the cylinder wall is three rings. Can be higher than the oil ring. Therefore, when the piston ring descends in the cylinder, the oil film thickness between the outer peripheral portion of the piston ring and the cylinder wall surface can be made smaller than in the case of a piston device having a three-ring configuration.

Therefore, the piston device equipped with the piston ring 22 of the present invention can suppress the consumption of lubricating oil. Further, in the piston device equipped with the piston ring 22 of the present invention, the contact surface pressure between the outer peripheral portion of the piston ring and the cylinder wall surface can be made higher than that of the conventional single-ring piston device shown in FIG. Oil consumption can be reduced compared to the piston device shown in FIG.

In the piston device of the single-ring configuration to which the piston ring of the present invention described above is applied, the oil escape hole 17 is provided at the upper end of the oil reservoir groove 11, but the position of the oil reservoir groove 11 is set at this position. Not limited, oil escape hole 17
Can be provided at the position of the second land 5 including the upper end of the oil reservoir groove 11, or can be at the center of the bottom of the oil reservoir groove.

The vertical width of the top ring groove 1 in the piston device having a single ring structure to which the piston ring of the present invention is applied varies depending on the cylinder capacity.
For a four-cycle gasoline engine, it can be 0.8-1.5 mm. The width of the top land in the vertical direction of the piston in the piston apparatus having a single ring to which the piston ring of the present invention is applied may be reduced to reduce the clevis volume, and varies depending on the cylinder capacity. The shape of the top land is not particularly limited, and the diameter of the top land is such that the top land does not come into contact with the cylinder wall during piston slap motion in a thermally expanded state when the engine is installed in an engine and operated. .

The maximum diameter of the second land in the piston device having a single ring structure to which the piston ring of the present invention is applied is the same as that of the above-mentioned top land, when the piston slap is in a thermally expanded state when assembled and operated in the engine. The diameter should be such that the maximum diameter of the second land does not contact the cylinder wall during movement. In the single-ring type piston device to which the piston ring of the present invention is applied, the outer diameter of the second land can be reduced continuously or stepwise from the top to the bottom.

Further, the piston device to which the piston ring of the present invention is applied is not limited to a piston device having a single ring structure, and a top ring in a piston device having a two ring structure and a top ring in a piston device having a three ring structure. , A second ring, and a pressure ring of a piston device of an internal combustion engine.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A piston ring shown in FIG. 2 is mounted on a top ring groove of a piston having a single ring structure shown in FIG. 1 and incorporated into an engine, and fuel consumption, lubricating oil consumption and blow-by gas amount are measured under various operating conditions. Investigations were made as invention examples. The bore diameter is 81 mm, the height from the piston top surface to the upper end of the skirt is 8.5 mm, the tension of the piston ring is the same as that of the oil ring in the three-ring piston device, and the lower ring thickness a _{1 of the} ring body is 1.5mm dimensions, 5 mm ring width h _1, the height h ₂ of 0.7 mm from the lower surface of the ring body to the corner portion of the ring body, also second land 5
The distance between the outer peripheral surface of the cylinder and the cylinder wall 21 is 0.1 to 0.2 mm
The oil escape holes were formed by drilling four holes each having a diameter of 1 mm in the circumferential direction at the upper end of the oil reservoir groove and perpendicularly to the cylinder wall surface 21.

As a conventional example, a piston ring having a bore diameter of 81 mm and a height of 17.5 mm from the top of the piston to the upper end of the skirt is used, and a piston ring corresponding to each ring groove is mounted with a predetermined tension. The other conditions were the same as those of the invention example, and the fuel consumption, consumption of lubricating oil and blow-by gas amount were investigated. As a result, in the invention example, both the gas sealing performance and the oil control performance can be satisfied even at a low tension, the blow-by gas amount can be equalized, and the consumption amount of the lubricating oil can be made as compared with the piston device having three rings. Was reduced.

Also, in the invention example, the mass of the piston head could be reduced, so that the fuel consumption could be reduced by 2 to 3% compared to the piston device having a three-ring configuration.

[0046]

According to the present invention, the contact surface pressure between the outer peripheral surface of the piston ring and the cylinder wall surface can be increased, and at least half of the thickness of the lower ring of the piston ring is brought into close contact with the lower surface of the ring groove, The piston ring can follow the cylinder wall. As a result, a piston device for an internal combustion engine having a single ring configuration that can reduce fuel consumption and satisfy both gas sealing performance and oil control performance becomes possible.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a piston device having a single ring using a piston ring of the present invention.

FIG. 2 is a longitudinal sectional view of a main part showing a mounted state of a piston ring of the present invention.

FIG. 3 is a longitudinal sectional view of a main part showing an operation of the piston device to which the present invention is applied.

FIG. 4 is a longitudinal sectional view of a main part of a conventional piston having three ring grooves.

FIG. 5 is a longitudinal sectional view of a main part of a conventional piston having two ring grooves.

FIG. 6 is a longitudinal sectional view of a main part of a conventional piston having one ring groove.

[Explanation of symbols]

10, 100, 200, 300 Piston 1 Top ring groove 4 Top land 5 Second land 8 Skirt 9 Piston top surface 11 Oil sump groove 17 Oil escape hole 21 Cylinder wall surface 22 Piston ring 22A Ring body 22B Expander 22C Seal ring P gas contact width S top pressure H groove width a ₁ lower ring thickness (a ₁ dimension) h ₁ ring height C ring outer periphery and the cylinder wall of the body from the lower surface of the width h ₂ ring body to the corner portion of the ring body Radial length of the lower surface of the ring body in close contact with the lower surface of the ring groove g Spacing between the outer peripheral surface of the second land 5 and the cylinder wall 21 L Lubricating oil

Claims (2)

[Claims] 1. A piston ring mounted in a ring groove provided in a piston of an internal combustion engine, the piston ring including an L-shaped ring main body, an expander for applying tension to the ring main body, and a seal ring. The ratio between the height from the lower surface of the ring body to the inner corner of the ring body and the ring width of the ring body is set to 1/3 or more and 1/2 or less, and the inner corner of the ring body is A seal ring is provided in close contact with the inclined surface of the ring groove facing the corner, and the outer peripheral surface of the land formed at the lower part of the ring groove and the cylinder wall surface at the lower part of the ring body. 2 times or more, and 1.5 times the ring width of the ring body
A piston ring characterized by being no more than twice. 2. The piston ring according to claim 1, wherein an outer peripheral surface of the ring main body is widened toward a lower portion of the ring main body.