JPH07332495A - Piston ring for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent lowering of airtightness of the inner wall of a cylinder by a method wherein a resilient substance is arranged at the abutment part of a ring body and a ring body is radially expanded through the resilient force thereof. CONSTITUTION:The outer peripheral surface 2 of a ring body 1 forms a barrel face type and has an abutment part 6 consisting of a pair of protrusions 1a. Further, a coil spring 5 formed of a wire rod for a spring formed in an oblong shape or an oval shape in modified cross section is arranged between notch parts 4 formed in the abutment part 6 and positioned facing each other. A pair of end parts 5a are brought into contact with respective corresponding notch parts 4. When, after the ring body 1 is mounted on the ring groove of a piston, a piston is arranged in a cylinder, the notch parts 4 are pressed in a peripheral direction through the force of the spring 5. Thereby, airtightness between the ring body 1 and the cylinder is ensured.

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 in an internal combustion engine, and more particularly to a compression ring which does not increase oil consumption and blow-by gas.

[0002]

2. Description of the Related Art A piston of an internal combustion engine is equipped with three to four piston rings, and the upper two to three piston rings maintain airtightness between a combustion chamber and a crank chamber.
It is called a compression ring that transfers the heat of the piston to the cylinder and radiates it. The lower one or two are called an oil ring, and have an action of forming an oil film on the inner surface of the cylinder and scraping off excess oil. As is well known, the piston ring is formed with an abutment portion for mounting in the ring groove of the piston. At the abutment, the end of the piston ring is cut in the radial direction, and is generally formed as a straight cut surface, and the outer peripheral surface of the piston ring is formed as a curved barrel face type. The barrel face type piston ring has the advantages of preventing scuffing during operation of the internal combustion engine and obtaining good initial familiarity.

[0003]

When an internal combustion engine equipped with a conventional piston ring is operated and the number of revolutions is increased,
The inertial force of the piston ring increases, and the airtightness of the side surface of the piston ring decreases. For this reason, there arises a problem that the amount of blow-by gas increases. As a countermeasure against this, the internal combustion engine for high-speed rotation for two-wheeled vehicles (motorcycles) has a structure shown in FIG.
As shown by, the outer peripheral surface 2 was formed with a barrel face and the width (B) of the top ring 1 was thinned. However, in proportion to reducing the width of the top ring 1,
Since the tension of the top ring 1 is also reduced, this in turn causes an increase in oil consumption and also an increase in blow-by gas amount under no load or high rotation. In addition, in the actual design of the top ring, if the width T is not reduced and the thickness T is not reduced at the same time, the side ring may be twisted due to the stress difference between the inner circumference and the outer circumference of the top ring, or the buckling may occur. There was a drawback that occurred. Therefore, when the width of the top ring is reduced, the thickness must be reduced at present.

As described above, a piston ring having a thin width B,
Especially as a simple method to improve the tension of the top ring,
It is conceivable to increase the free abutment gap L, increase the thickness T, and use a material having a higher Young's modulus. However, when the free abutment gap L or the thickness T is increased, when a piston equipped with a piston ring is arranged in the cylinder, the stress in use that is generated on the outer circumference of the piston ring on the side opposite in diameter of the abutment portion increases. ,
It may break. The material currently used for piston rings is Young's modulus E = 20,000 to 22,000K.
g / mm ² stainless steel or chrome molybdenum steel, there is no usable material that significantly exceeds these materials in the method of increasing Young's modulus.

Therefore, an object of the present invention is to provide a piston ring for an internal combustion engine in which the airtightness with respect to the inner wall of the cylinder is not reduced.

[0006]

In a piston ring for an internal combustion engine according to the present invention, an elastic body is arranged at an abutment portion of a ring body, and both ends of the elastic body are brought into contact with corresponding both ends of the ring body, and elastic The elasticity of the body expands the ring body in the radial direction. In an embodiment of the present invention, the elastic body is either a metallic coil spring or leaf spring, resin, a shape memory alloy whose length increases at high temperature, or a material which causes thermal expansion at high temperature. Leaf springs are U-shaped, V-shaped or rhombic in cross section. A pair of protrusions may be provided that project from each end of the ring body in a circumferential direction that are close to each other. A lug or a recess is formed at an end of the ring body that constitutes the abutment, and the elastic body is locked in the lug or the recess. The elastic body integrally forms lips that respectively project from the ends of the ring main body forming the abutment portion with the ring main body, and abuts the opposing lips against each other to generate circumferential elastic force.

[0007]

Since the elastic body is arranged at the abutment portion, when the piston equipped with the piston ring is arranged in the cylinder, the elastic force of the elastic body expands the diameter of the piston ring and presses it against the inner wall of the cylinder. As a result, the sealability of the piston ring can be ensured in the entire rotation range including high speed rotation.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a piston ring for an internal combustion engine according to the present invention will be described below with reference to FIGS.

FIG. 1 is a plan view of a piston ring for an internal combustion engine according to a first embodiment of the present invention. Although not shown,
The outer peripheral surface 2 of the ring body 1 is formed into a barrel face type. A coil spring 5 is arranged as an elastic body in the facing notch 4 provided in the abutment portion 6 of the ring body 1 having the abutment portion 6 formed by the pair of protrusions 1a.
The spring 5 is formed of a wire material for spring having an irregular cross section such as a rectangle or an ellipse. The cutout portion 4 is formed on the inner peripheral portion 3 side of the ring body 1. A pair of ends 5 of the spring 5
a abuts on each corresponding notch 4. After mounting the ring body 1 shown in FIG. 1 in the ring groove (not shown) of the piston and then disposing the piston in the cylinder, the notch 4 is pressed by the spring 5 in the circumferential direction. Therefore, airtightness between the ring body 1 and the inner wall of the cylinder is ensured.

In the second embodiment shown in FIG. 2, a coil spring 5 formed of a normal wire material for a spring having a circular cross section is arranged. Each notch 4 of the ring body 1 is provided with a lug 7 projecting in the circumferential direction. As shown in FIGS. 2 and 3, the end of the spring 5 is locked by the lug 7, so that the spring 5 does not fall off. Are prevented by the lug 7. As shown in FIG. 3, when the ring main body 1 is arranged in the ring groove 11 of the piston 10, the barrel face type outer peripheral surface 2 becomes the cylinder 12.
Abut the inner wall of. The cross section of the spring 5 has a size that does not protrude from the cross section of the cutout 4. Instead of forming the lug 7, as shown by a dotted line in FIG. 2, the end 5a of the spring 5 is arranged in the recess 8 formed in each notch 4 to prevent the spring 5 from coming off. May be.

In the third embodiment shown in FIG. 4, a leaf spring 5 having a U-shaped cross section is arranged between a pair of notches 4. The end portion 5a of the leaf spring 5 presses the pair of cutout portions 4 in a direction in which they are separated from each other. In this case, the through hole 5b may be formed in the end portion 5a, and the lug 7 may be attached to the through hole 5b to prevent the leaf spring 5 from falling off.

FIG. 5 shows a fourth embodiment in which a resin 15 made of a polyimide resin (trade name: Vespel, DuPont) or polyetherketone (PEEK) is arranged between a pair of notches 4 as an elastic body. Vespel is 25 ~ 300 ℃
The linear expansion coefficient is 53, PEEK is 25 to 150 ° C., and the linear expansion coefficient is 85, which is about 4 to 8 times the linear expansion coefficient of cast iron 10 to 12 and the linear expansion coefficient of stainless steel 15 to 17. The resin 15 is mounted in the cylinder, and when heated, expands to generate an elastic force that urges the pair of notches 4 in the direction of separating them. In this case, a slit may be formed in the resin 15 to give the resin a predetermined rigidity. The resin 15 may also be engaged with a lug or recess, as shown in FIG.

FIG. 6 is an alternative to the U-shaped section shown in FIG.
5 shows a fifth embodiment using a leaf spring 5 having a V-shaped cross section. As shown by the dotted line, the leaf spring 5 having a V-shaped cross section has an increased V-shaped angle in the free state. The leaf spring 5 of V-section in FIG. 6 may also be engaged with a lug or recess, as shown in FIG.

FIG. 7 shows a sixth embodiment in which a leaf spring 5 having a rhombic cross section having a gap 5b formed therein is used.
The dotted line shows the free state of the leaf spring 5 which is expanded during heating.

The springs shown in FIGS. 1, 2, 4, 6, and 7 may use shape memory alloys whose length increases at high temperatures. Further, in the above-mentioned embodiment, it is important that each elastic body has a cross section smaller than that of the ring main body as shown in FIG. 3 and does not project outward from the ring main body.

In FIGS. 8 and 9, a pair of lips 1b projecting from the end of the ring body 1 are integrally formed with the ring body 1 as elastic bodies, and the opposite lips 1b are brought into contact with each other to form a circumferential direction. A seventh embodiment for producing the elasticity of
In this embodiment, the protrusions 1a of the ring body 1 overlap in the width direction, which is more effective in preventing blow-by gas generation.
There is an advantage that the number of parts does not increase.

In the first to seventh embodiments, since the elastic body is arranged at the abutment portion 6, when the piston equipped with the piston ring is arranged in the cylinder, the elastic force of the elastic body expands the diameter of the piston ring. , Is pressed against the inner wall of the cylinder. As a result, the sealability of the piston ring can be ensured in the entire rotation range including high speed rotation.

In practice, a piston ring having a nominal diameter of 60 mm is manufactured, and a coil spring 5 shown in FIG. 1 which produces a tension of about 1 kg is attached to the piston ring in accordance with the present invention as compared with a conventional piston ring having a tension of 0.5 kg. It was mounted on an in-line 4-cylinder gasoline engine with a displacement of 660 cc. The engine was operated at 7000 rpm and the throttle fully opened at 4/4 load, and the oil consumption and blow-by gas amount were measured when the piston ring according to the present invention and the conventional piston ring were used. Coil spring 5 wire diameter 0.3 mm, tension 500 g, spring constant 1.5, winding diameter 1.0
mm, and the mounting dimension was 3.8 mm. The piston ring uses chrome molybdenum steel with chrome plating on the outer peripheral surface, Young's modulus of 20,000 Kg / mm ² , B × T = 1.
It was 0 mm × 2.6 mm. As a result, the oil consumption was reduced by about 40% in the engine using the piston ring of the present invention as compared with the engine using the conventional piston ring. Further, when comparing under no load conditions from 2000 to 7000 rpm, in the engine using the piston ring according to the present invention, the blow-by gas amount is 20 compared with the engine using the conventional piston ring.
The amount was almost the same from 00 to 4000 rpm, but 50
20% at 00 rpm, 6000 rpm up to 70 rpm
It was halved at 00 rpm. Thus, field tests have shown that the piston ring according to the invention can reduce oil consumption and blow-by gas quantity.

[0019]

As described above, according to the present invention, since the piston ring is constantly pressed against the inner wall of the cylinder, the tight contact between the piston ring and the cylinder due to the inertia force of the piston ring during the operation of the internal combustion engine is prevented. As a result, the oil consumption amount and the blow-by gas amount can be reduced. Therefore, it is possible to operate the internal combustion engine in a good condition for a long period of time and prevent a malfunction.

[Brief description of drawings]

FIG. 1 is a plan view showing a first embodiment of a piston ring for an internal combustion engine according to the present invention.

FIG. 2 is a plan view of a second embodiment according to the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a plan view showing a third embodiment according to the present invention.

FIG. 5 is a plan view showing a fourth embodiment according to the present invention.

FIG. 6 is a plan view showing a fifth embodiment according to the present invention.

FIG. 7 is a plan view of an elastic body showing a sixth embodiment according to the present invention.

FIG. 8 is a plan view showing a seventh embodiment according to the present invention.

9 is a perspective view of FIG.

FIG. 10 is a partial perspective view showing an abutment portion of a conventional piston ring.

[Explanation of symbols]

1 ... Ring body, 1a ... Protrusion, 2 ... Outer peripheral surface, 3 ... Inner peripheral surface, 4 ... Notch portion, 5 ... Spring, 5a ... End portion, 6 ... ..Abutment portions, 7 ... lugs, 8 ... concave portions, 10 ... pistons, 11 ... ring grooves, 12 ... cylinders, 15 ... resin,

Claims (6)

[Claims] 1. An elastic body is arranged at the abutment portion of the ring body,
A piston ring for an internal combustion engine, characterized in that both ends of the elastic body are brought into contact with corresponding both ends of the ring body, and the ring body is radially expanded by the elastic force of the elastic body. 2. The elastic body is formed of a metal coil spring or leaf spring, a resin, a shape memory alloy whose length increases at high temperature, or a material which causes thermal expansion at high temperature. Piston ring for internal combustion engine. 3. The piston ring for an internal combustion engine according to claim 1, further comprising a pair of protrusions that are arranged to approach each other from each end of the ring body and project in a circumferential direction. 4. The piston ring for an internal combustion engine according to claim 1, wherein a lug or a recess is formed at an end portion of the ring body which constitutes the abutment portion, and the elastic body is locked in the lug or the recess. 5. The piston ring for an internal combustion engine according to claim 2, wherein the leaf spring has a U-shaped, V-shaped or rhombic cross section. 6. The elastic body is formed integrally with the ring main body, with lips projecting from the ends of the ring main body forming the abutment portion, and opposing lips are brought into contact with each other to generate elastic force in the circumferential direction. 1. A piston ring for an internal combustion engine according to 1.