JP2003286899A - Combination oil ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combination oil ring which can reduce blow-by gas. <P>SOLUTION: The combination oil ring 4 comprises the oil ring 5 of an approximately I-shaped cross section which is formed of vertical rails 7, 8 and a web 9, and a coil expander 6. An oil return hole 14 penetrating in the axial direction and communicating with an outer peripheral groove 13 of the oil ring 5 is formed in the rail 8 on its lower side. An oil return passage 15 is formed on the lower face 3a of a ring groove 3 of a piston 1. The oil return passage 15 is formed so as to be deeper in the radial direction than the oil return hole 14 of the oil ring 5 and to be shallower in the radial direction than the thickness in the radial direction of the oil ring 5. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined oil ring mounted on a piston of an internal combustion engine.

[0002]

2. Description of the Related Art In a reciprocating internal combustion engine, as an oil ring, as shown in FIG. 7, a combined oil ring 4A including an oil ring 5A having a pair of upper and lower rails 7 and 8A and a coil expander 6. Is used. The oil ring 5A has a substantially I-shaped cross section, and is composed of a pair of upper and lower rails 7 and 8A and a web 9A connecting these rails. An oil return hole 14A is provided in the web 9A to provide the upper rail 7A. The oil scraped off from the inner wall of the cylinder 2 passes through the oil return hole 14A of the web 9A, passes through the oil return passage 15A provided on the bottom surface 3b and / or the lower surface 3a of the ring groove 3 of the piston 1, and then reaches the oil pan. It is configured to be returned.

[0003]

However, the combustion gas flows from the rear surface of the oil ring 5A to the oil return passage 15A of the piston 1 and the oil return hole 14A of the oil ring 5A.
Leaks through. Further, the oil leaks from the joint of the oil ring 5A through the outer peripheral groove 13 between the upper and lower rails 7 and 8A and through the oil return hole 14A.

The present invention has been made in view of the above points, and an object thereof is to provide a combined oil ring capable of reducing blow-by gas.

[0005]

The present invention adopts the following means in order to solve the above problems. That is, the present invention is
The expander is used by arranging an expander on the inner peripheral side of an oil ring having two upper and lower rails on the outer peripheral side and an outer peripheral groove between the rails, and an oil return hole communicating with an oil return passage provided in a piston is used for the oil. In the combination oil ring formed in the ring, the oil return hole of the oil ring is formed of a through hole penetrating the lower rail of the oil ring and communicating with the outer peripheral groove.

According to the above construction, it is possible to prevent gas leakage from the rear surface of the oil ring through the oil return passage of the piston and the oil return hole of the oil ring, so that the gas sealing performance of the combined oil ring can be improved.

It is desirable that the radial thickness of the lower portion that contacts the lower surface of the ring groove of the oil ring is thicker than the radial thickness of the upper portion. According to this structure, the contact area between the lower surface of the oil ring and the lower surface of the ring groove of the piston can be increased, so that the gas sealing performance can be improved.

It is desirable that the end of the outer peripheral groove of the oil ring facing the abutment is closed. According to this structure, the gap between the gap and the outer peripheral groove between the upper and lower rails can be blocked by the closed end, so that gas leak from the outer peripheral groove between the upper and lower rails can be eliminated. ,
The gas seal performance can be improved. Further, it is preferable that a concave portion is provided on an end surface of one closed end portion facing the abutment of the outer peripheral groove, and a projection to be inserted into the concave portion is projectingly formed on an end surface of the other closed end portion. With this configuration,
Since gas leakage through the joint can be reduced, the gas sealing performance can be further improved.

The oil return passage of the piston is formed on the outer peripheral surface of the piston and is formed on the lower surface of the ring groove of the piston, or is opened on the outer peripheral surface of the piston and is formed on the entire lower surface of the ring groove of the piston. It is formed of a stepped portion. In the case of grooves, it is preferable to provide a plurality of grooves at intervals in the circumferential direction of the piston. Further, it is desirable from the viewpoint of gas sealing that the oil return passage of the piston has a radial depth that is shallower than the radial thickness of the oil ring.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a piston, 2 is a cylinder, and a combination oil ring 4 is mounted in a ring groove 3 formed on the outer periphery of the piston 1.

The combination oil ring 4 is a two-piece steel combination oil ring, and includes an oil ring 5 and
It consists of a coil expander 6.

The oil ring 5 (see FIG. 2) is a steel ring having a substantially I-shaped cross section, and has a pair of upper and lower rails 7 and 8 extending in the circumferential direction and the above-mentioned extending in the circumferential direction. The straight web 9 connects the pair of rails 7 and 8.

A coil expander 6 is mounted in an inner peripheral groove 10 formed by the upper and lower rails 7 and 8 and the web 9. The coil expander 6 pushes the oil ring 5 outward in the radial direction to press the outer peripheral sliding surfaces 11, 12 of the upper and lower rails 7, 8 of the oil ring 5 against the inner wall of the cylinder 2.

An outer peripheral groove 13 formed by the upper and lower rails 7 and 8 of the oil ring 5 and the web 9 is an oil receiving groove. A plurality of oil return holes 14 are formed in the lower rail 8 and are formed as through holes that extend axially and communicate with the outer peripheral groove 13 at circumferential intervals. The oil return hole 14 is formed so as to slightly cover the web 9 portion. Therefore, the oil scraped off from the inner wall of the cylinder 2 by the outer peripheral sliding surfaces 11 and 12 of the upper and lower rails 7 and 8 passes through the oil return hole 14 from the outer peripheral groove 13 and is formed on the lower surface 3a of the ring groove 3 of the piston 1. The oil returns into the oil return passage 15 and is dropped into the oil pan from between the outer circumference of the piston 1 and the inner wall of the cylinder 2.

Since the oil return hole is not formed in the web 9 of the oil ring 5, the gas flowing into the back surface of the oil ring 5 does not leak through the oil return hole of the oil ring, which is a conventional problem. The gas sealing performance is improved.

The oil return passage 15 formed in the lower surface 3a of the ring groove 3 of the piston 1 is formed as follows. That is, as shown in FIGS. 1 and 3, the groove 15a is formed on the lower surface 3a of the ring groove 3 of the piston 1 and is open to the outer peripheral surface 1a of the piston 1. A plurality of grooves 15a are provided at intervals in the circumferential direction of the piston 1. 3 (a) shows the case where the groove 15a is a circular arc groove, and FIG. 3 (b) shows the case where the groove 15a is a rectangular groove. Alternatively, as shown in FIG. 4, a step portion 15b may be formed on the lower surface 3a of the ring groove 3 of the piston 1 over the entire circumference and open to the outer peripheral surface 1a of the piston 1.

As shown in FIG. 1, the oil return passage 15 is formed deeper in the radial direction than the oil return hole 14 of the oil ring 5 and shallower in the radial direction than the radial thickness of the oil ring 5. . According to this structure, since the oil return passage 15 does not communicate with the back surface of the oil ring 5, the gas flowing into the back surface of the oil ring 5 does not leak through the oil return passage of the piston, and the gas does not leak. The sealing performance is improved.

As shown in FIG. 4, if the radial thickness of the lower portion contacting the ring groove lower surface 3a of the oil ring 5 is made thicker than the radial thickness of the upper portion, the lower surface of the oil ring 5 is formed. And the lower surface 3 of the ring groove 3 of the piston 1
Since the contact area with a can be increased, the gas sealing performance can be improved.

As shown in FIG. 5, if the end of the oil groove 5 facing the abutment of the outer peripheral groove 13 is closed, the gap between the abutment and the outer peripheral groove 13 is closed. Since it can be blocked at the end portion 16, it is possible to eliminate gas leakage from the gap through the outer peripheral groove 13 between the upper and lower rails 7 and 8. The end of the outer peripheral groove 13 facing the abutment can be closed by means of thermal spraying, welding, bonding, plating or the like. Further, as shown in FIG.
Of the one closed end 16 facing the abutment
Is provided, and the protrusion 18 to be inserted into the recess 17 is formed so as to project from the end surface of the other closed end portion 16, it is possible to reduce gas leakage through the gap.

[0021]

As described above, the combined oil ring of the present invention can reduce blow-by gas.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a part of an oil ring.

FIG. 3A and FIG. 3B are perspective views showing an oil return passage portion formed on the lower surface of the ring groove of the piston.

FIG. 4 is a vertical sectional view showing another embodiment of the present invention.

FIG. 5 is a perspective view showing a mating end portion of an oil ring.

FIG. 6 is a front view showing an end portion of an oil ring.

FIG. 7 is a vertical sectional view showing a conventional example.

[Explanation of symbols]

1 piston 2 cylinders 3 ring groove 3a Lower surface of ring groove 4 combination oil ring 5 oil ring 6 coil expander 7,8 rails 9 Web 13 peripheral groove 14 Oil return hole 15 Oil return passage 15a groove 15b step 16 closed end 17 recess 18 protrusions

Continued front page    (72) Inventor Tomoaki Abe             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. F term (reference) 3J044 AA14 CA09 CB01 CB06 CB30                       CB38 DA09 DA17

Claims (8)

[Claims] 1. An oil which is used by arranging an expander on the inner peripheral side of an oil ring having two upper and lower rails on the outer peripheral side and an outer peripheral groove between the rails, and which communicates with an oil return passage provided in a piston. In a combined oil ring having a return hole formed in the oil ring, the oil return hole of the oil ring is formed of a through hole penetrating a lower rail of the oil ring and communicating with an outer peripheral groove. A combination oil ring featuring. 2. The radial thickness of the lower portion that contacts the lower surface of the ring groove of the oil ring is thicker than the radial thickness of the upper portion.
The described combination oil ring. 3. The combined oil ring according to claim 1, wherein an end portion of the outer peripheral groove of the oil ring facing the abutment is closed. 4. A concave portion is provided on an end surface of one closed end portion facing the abutment of the outer peripheral groove, and a projection to be inserted into the concave portion is formed to project on an end surface of the other closed end portion. The combination oil ring according to claim 3, which is characterized. 5. The combined oil ring according to claim 1, wherein the oil return passage of the piston is formed by a groove which is open to an outer peripheral surface of the piston and which is formed on a lower surface of a ring groove of the piston. . 6. The combined oil ring according to claim 5, wherein a plurality of the oil return grooves are provided at intervals in the circumferential direction of the piston. 7. The oil return passage of the piston is formed by a step portion which is open to the outer peripheral surface of the piston and is formed on the lower surface of the ring groove of the piston over the entire circumference. Combination oil ring. 8. The combination oil ring according to claim 5, wherein the oil return passage of the piston has a radial depth smaller than the radial thickness of the oil ring.