JPH07217740A - Thin width three piece oil ring - Google Patents

Abstract

PURPOSE:To improve the followability to the internal wall and performance in a high speed range of a thin width three piece oil ring comprising a spacer expander formed of a section steel material whose cross section is almost H- shape and to improve the machining accuracy in machining a section steel material into a spacer expander. CONSTITUTION:A chevron-shape recessed notch 18 is formed in the internal peripheral surface of a thick part 11 in the internal peripheral side of a spacer expander 10 to easily elastically deform the upper and lower halves of the internal peripheral surface side thick part 11 for pressing side rails 20 and 20' against the internal wall 42 of a cylinder and also reduce the weight of the spacer expander 10. In addition, the section material, when curled, can be automatically aligned to a work roll.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil ring used in an internal combustion engine, and more particularly to an improvement of a three-piece combined oil ring mounted in an axially thin oil ring groove. Is.

[0002]

2. Description of the Related Art Along with high engine speed, high output, and low fuel consumption, there is a demand for thinner pistons and piston rings and improved oil ring sealability. A thin three-piece combination oil ring having a good sealing property is disclosed in JP-A-4-78.
No. 376. This known oil ring is formed of a shaped steel material having an approximately H-shaped cross section, and has a spacer expander of an annular torus shape in which slits are alternately cut from the inner peripheral side and the outer peripheral side, and the spacer expander is vertically moved. It is an oil ring consisting of two side rails that are combined so as to be sandwiched between the side expander and the outer side of the spacer expander. The side rail bearing surface has an inner peripheral edge whose radial inclination angle is in the range of 1 degree to 15 degrees, is inclined toward the center of the axial width, or whose radial width is the spacer expander cross-section radius. It is formed on the radial extension surface of 20% or less of the width in the direction,
The side rail pressing surface was formed as an inclined surface having a root in the range of an inclination angle in the axial direction of 15 degrees to 25 degrees, which is outward. This oil ring can be thinned to an axial width of 3 mm or less, and since the side rail is brought into close contact with the upper and lower surfaces of the oil ring groove by the side rail pressing surface, the sealing performance is improved and the side rail posture is stable. Was there.

[0003]

However, since the spacer expander of the known oil ring has a relatively large rigidity at the inner peripheral side enlarged portion, the elastic deformation due to the load received from the side rail is small, and the side rail with respect to the inner wall of the cylinder is not deformed. The followability was not necessarily good. For example,
If the cylinder is deformed or the like, either the upper or lower side rail may not contact the inner wall of the cylinder, or the tension may be reduced even if the side rails are in contact. or,
Since the inner peripheral side enlarged portion of the spacer expander has a relatively large cross-sectional area, it has a large weight and adversely affects the behavior as an oil ring. For example, there is a possibility that oil consumption may increase in the high speed rotation range. Further, when the spacer expander of this oil ring is curled from the shaped steel material, the inner peripheral side and outer peripheral side enlarged parts are fitted in the grooves on the peripheral surface of the working roll, but the clearance of the grooves causes axial swaying and causes twisting or deformation. There is a problem that defective products are likely to occur.

The present invention has been made to solve the above problems, and an object of the present invention is to improve the followability of a thin three-piece combination oil ring equipped with a spacer expander made of die steel. , To improve the performance in the high-speed rotation range.

[0005]

To achieve the above object, the means adopted by the present invention is to form a recessed portion on the inner peripheral surface of the spacer expander. The recessed portion has a mountain shape symmetrical with respect to the axial direction of the spacer expander, that is, the upper and lower center lines. Further, a similar recess may be formed on the outer peripheral surface of the spacer expander.

[0006]

[Function] Since the upper and lower halves of the inner peripheral enlarged portion have a narrower radial width at the base due to the recessed portion formed on the inner peripheral surface of the spacer expander, the inner peripheral enlarged portion upper and lower portions are rigid. Becomes smaller and elastically deforms easily. As a result, even if the inner wall of the cylinder is deformed, the side rail can surely follow. Further, by forming the recessed portion, the weight of the spacer expander is reduced and the inertial force is also reduced, so that the risk that the behavior of the oil ring is disturbed in the high speed rotation range is reduced. Furthermore, if the concave notch is formed in a chevron shape and a chevron that fits into the chevron is provided in the groove of the processing roll, the die steel material is self-centered by the fitting of the chevron and the shaking during machining is prevented. The deformation of the spacer expander is improved and the processing accuracy is improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An oil ring of the present invention will be described based on the embodiments shown in the drawings. As shown in FIG. 1, the three-piece combination oil ring includes a spacer expander 10 of a torus shape formed by a processing roll from a steel material having a substantially H-shaped cross section.
It is provided with two side rails 20 and 20 'that sandwich it from above and below. The spacer expander 10 is composed of an inner peripheral side enlarged portion 11, an outer peripheral side enlarged portion 12, and an intermediate portion 13 connecting both enlarged portion, and slits 14 and 15 are alternately cut from the inner peripheral side and the outer peripheral side. The outer peripheral up and down slopes of the inner peripheral side enlarged portion 11 contact the inner peripheral side end portions 21 and 21 'of the upper and lower side rails 20 and 20' as side rail pressing surfaces 16 and 16 ', and the upper and lower surfaces of the outer peripheral side enlarged portion 12 Is the upper and lower side rails 20 as side rail bearing surfaces 17 and 17 '.
It contacts the inner surface 22, 22 'of 20'. A concave notch 18 is formed on the inner peripheral surface of the inner peripheral side enlarged portion 11, and upper and lower half parts 19, 19 of the inner peripheral side enlarged portion 11 are formed.
The width in the radial direction at the base of ′ is reduced.

As shown in FIG. 2, the oil ring is mounted in the oil ring groove 32 of the piston 30 and fitted in the cylinder 40. Spacer expander 10 is side rail bearing surface 1
The side rails 20 and 20 'are axially supported by 7, 17', and the side rail pressing surfaces 16, 16 'are side rails.
The outer peripheral ends 23, 23 'of the 20, 20' are pressed against the cylinder inner wall 42. The concave notch 18 that cuts the inner peripheral surface of the inner peripheral side enlarged portion 11 has a mountain shape, and its center line coincides with the upper and lower center lines of the inner peripheral side enlarged portion 11. The recessed portion 18 reduces the weight of the spacer expander 10 and thus the inertia of the spacer expander 10 so that the behavior of the oil ring in the high speed rotation range of the engine is less likely to be disturbed by its own inertia.

As shown in FIG. 3, a spacer expander
The upper and lower half portions 19 and 19 ′ of the inner peripheral side enlarged portion 11 of 10 are elastically deformed,
The elastic repulsive force pushes the side rails 20, 20 'against the cylinder inner wall 42 to move the side rails 20, 20' into the cylinder inner wall.
Follow 42. Since the radial widths of the roots of the upper and lower half portions 19 and 19 'are thinned by the recessed portion 18, the upper and lower half portions 19 and 19' have low rigidity and are sufficiently elastically deformed. As a result, as shown by the chain line, even if the cylinder inner wall 42 has irregularities, the upper and lower halves 19, 19 ′ are elastically deformed as shown by the arrows to press the side rails 20, 20 ′, the outer peripheral end 23, 23 'is always brought into contact with the inner wall 42 of the cylinder.

As shown in FIG. 4, the die steel material 50 to be formed on the spacer expander is passed through processing rolls 51 and 52 for curling. The portion of the shaped steel material forming the inner and outer peripheral surfaces of the spacer expander is loosely fitted into the circumferential groove of each processing roll, and at this time, the concave groove is engaged with the circumferential groove 53 that loosely fits the inner surface of the spacer expander. When the convex portion 54 is provided, the concave portion of the die steel material and the convex portion of the circumferential groove are fitted to each other and self-aligning is performed, so that the sway of the die steel material 50 is restricted during machining, and the machining accuracy is improved.

Although the recessed portion of the above-described embodiment reaches the upper and lower surfaces of the enlarged portion on the inner peripheral side of the spacer expander, the recessed portion 18 is formed only on the inner side of the inner peripheral surface of the spacer expander 10, as shown in FIG. It is also possible to form. Further, as shown in FIGS. 6 and 7, the mountain-shaped apex of the recessed portion 18 of the spacer expander 10 can be flat or arcuate. In the embodiment of FIG. 8, the outer peripheral side enlarged portion 12 is also formed with a recess 25 on the outer peripheral surface. Since the spacer expander 10 is provided with the recessed portions 18 and 25 on both the inner peripheral side and the outer peripheral side enlarged portions 11 and 12, the weight is further reduced, and the behavior of the oil ring is disturbed even in the high speed rotation range of the engine. There is almost no danger of becoming. Further, as shown in FIG. 9, processing rolls on both sides
Since it is possible to perform the curling processing of the mold steel material 50 by forming the convex portions 54 and 56 that engage with the recessed notches in the circumferential grooves 53 and 55 of the 51 and 52, the rocking of the mold steel material 50 during processing is more reliable. The accuracy of the spacer expander is further improved.

[0012]

As described above, the three-piece combined oil ring provided with the spacer expander formed of the die steel material of the present invention has the inner circumference of the spacer expander that presses the side rail against the inner wall of the cylinder as compared with the conventional one. Since the side enlarged portion has a relatively small rigidity and is elastically deformed sufficiently, there is an effect that the side rail can follow the cylinder inner wall well.

Further, since the oil ring lightened by the recessed portion of the spacer expander does not have a possibility of disturbing the operation even in the high speed rotation range of the engine, the oil consumption can be reduced, thereby increasing the high output of the engine. This brings about an effect that it is possible to improve the fuel efficiency and fuel efficiency. In addition, when the spacer steel expander is formed by curling the die steel material, the die steel material can be automatically aligned by the recessed portion, which improves the machining accuracy and significantly reduces the occurrence of defective products such as twisting and deformation. The effect is reduced to.

[Brief description of drawings]

FIG. 1 is a perspective view showing a part of an oil ring according to a first embodiment of the present invention,

2 is a cross-sectional view showing a part of an engine equipped with the oil ring of FIG. 1,

FIG. 3 is a diagram showing the followability of the oil ring of FIG. 1 with respect to the cylinder inner wall;

FIG. 4 is a view showing a state of curling the spacer expander of the oil ring of FIG. 1,

FIG. 5 is a cross-sectional view of a spacer expander of the second embodiment,

FIG. 6 is a cross sectional view of a spacer expander of a third embodiment,

FIG. 7 is a cross-sectional view of a spacer expander of the fourth embodiment,

FIG. 8 is a cross-sectional view of a spacer expander of the fifth embodiment,

FIG. 9 is a view showing a state of curling the spacer expander of the fifth embodiment,

[Explanation of symbols]

10: Spacer expander, 11: Inner circumference enlarged section, 12: Outer circumference enlarged section, 13: Intermediate section, 14, 15: Slit, 16: Side rail pressing surface, 17: Side rail bearing surface, 18: Recessed notch Part, 19: upper and lower halves, 20: side rails, 21: inner peripheral edge, 2
2: Inner surface, 23: Outer peripheral edge, 30: Piston, 32: Oil ring groove, 40: Cylinder, 42: Cylinder inner wall,

Claims (3)

[Claims] 1. A spacer expander (10), which is an annular toroidal body and is formed from a shape steel material having a substantially H-shaped cross section, and two side rails (20, 20) sandwiching the spacer expander from above and below.
′), Slits (14, 15) for alternately cutting the spacer expander from the inner and outer peripheral surfaces, and side rail pressing surfaces (16, 16) formed above and below the outer peripheral side of the inner peripheral enlarged portion (11) of the spacer expander. 16 ′) and side rail bearing surfaces (17, 17 ′) formed above and below the outer peripheral side enlarged portion (12) of the spacer expander, the inner ring side enlarged portion (11 ), A concave cutout (18) is formed on the inner peripheral surface of the inner peripheral surface of the cylinder (40) to press the side rails (20, 20 ') against the inner wall (42) of the cylinder (40). , 19 ') is a thin width three-piece oil ring characterized by reducing the radial width of the root. 2. The center line of the recessed portion (18) has upper and lower halves (1
The thin three-piece oil ring according to claim 1, characterized in that it has a chevron shape that coincides with the upper and lower center lines of (9, 19 '). 3. A chevron-shaped recess (25) whose center line coincides with the upper and lower center lines of the outer peripheral enlarged portion (12) on the outer peripheral surface of the outer peripheral enlarged portion (12) of the spacer expander (10). The thin three-piece oil ring according to claim 1.