JP3801250B2 - Combination oil ring - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a two-piece combined oil ring for an internal combustion engine.
[0002]
[Prior art]
A diesel engine uses a two-piece type combined oil ring composed of an oil ring body 10 and a coil expander 20 as in an I-type oil ring shown in FIG.
[0003]
The oil ring main body 10 has two upper and lower rails 11a and 11b on the outer periphery. The upper and lower rails are connected by a web 12, and the web 12 is formed with an oil window 13 through which lubricating oil can pass. ing.
[0004]
If the oil ring is a steel ring, the rail part has an angle of 10 to 20 degrees because of its high strength, and the width D of the contact surface can be as narrow as 0.2 to 0.3 mm. High surface pressure can be secured while maintaining rail strength.
[0005]
However, these conventional oil rings have the following problems.
(1) Like the 2nd ring whose outer peripheral shape is a tapered shape, the effect of riding on the oil film in the piston ascending stroke is not obtained, and the amount of oil pumping up is large, which is disadvantageous in reducing the consumption of lubricating oil. .
[0006]
(2) Also, recent oil rings have a tendency to narrow the contact width D of the rail tip for the purpose of increasing the surface pressure of the sliding surface. It has also become clear. Therefore, there is a limit to the contact width D per rail, and it has become difficult to increase the surface pressure by narrowing the contact width.
[0007]
For example, Japanese Utility Model Publication No. 55-16128 proposes a single-rail oil ring as shown in FIG. 3 for the purpose of ensuring the surface pressure of the sliding surface, and the contact width thereof is that of a two-rail product. It is stated that the contact pressure can be increased because it can be halved. However, since the rail 11 is not in the central portion, the rail 11 is asymmetric with respect to the center line, and if an attempt is made to roll-form from a wire to this shape, twisting or the like occurs, making it difficult to form. In order to avoid this, as shown in FIG. 4 (b), the shape can be obtained by polishing the rail on one side of the symmetrical two-rail product. However, this increases the cost. it is obvious. Further, as shown in FIG. 3, the oil return window 13 must be punched out, but the more the window position is away from the center line, the more difficult it is to punch out.
[0008]
(3) By the way, the oil ring plays the role of ensuring airtightness like the other rings, while controlling the lubricating oil as a main role. In this way, efforts have been made to improve the airtightness while maintaining the control capability of the lubricating oil, and those described in Japanese Utility Model Laid-Open No. 6-16765 are typical examples. In this device, one side of the joint is formed into a convex shape and the other is formed into a concave shape, and both are engaged to improve the airtightness. In order to form this joint shape, the oil ring main body outer peripheral side There is one rail protruding so as to increase the diameter. This is because it is difficult to manufacture such a joint shape with an oil ring having two rails.
[0009]
Another problem with this ring is that it is impossible to satisfy the above-mentioned joint shape and the high surface pressure of the sliding surface at the same time. This is because, if the above-mentioned joint shape is formed at the same time that the width per rail front end portion is narrowed in order to ensure high surface pressure, practical joint joint rail strength cannot be obtained. In this oil ring, it is clear that priority is given to securing the joint shape. Further, as a device relating to a single rail, there is one described in Japanese Utility Model Publication No. 55-28840, and the invention of an oil ring of a single rail is not already novel, so that It is clear that the novelty of the device described in Japanese Patent No. 16765 is in the joint shape. The above analysis reveals that it is difficult to further narrow the width per oil ring sliding surface of the Japanese Utility Model Laid-Open No. 6-16765.
[0010]
[Problems to be solved by the invention]
It is to realize an oil ring that reduces the amount of lubricating oil consumption by suppressing the oil scooping action during the piston ascent stroke or by amplifying the oil scraping action during the pistol descending stroke.
[0011]
[Means for Solving the Problems]
As shown in FIG. 1, the oil ring of the present invention has one rail protruding at the central portion of the outer peripheral surface of the main body, and has the rail outer peripheral shape shown below, thereby solving the above problem.
[0012]
(1) As shown in FIG. 1, the outer peripheral shape of the cross section of the rail tip of the oil ring body 10 is arranged continuously with the contact surface 14 that is in parallel with the cylinder surface 40, and the ring diameter from the top to the bottom. Has a tapered surface 15 for expanding the diameter.
[0013]
(2) As shown in FIG. 2, the oil ring main body 10 protrudes at the center of the outer peripheral surface so as to increase the ring diameter, and the tip has a contact surface 16 parallel to the cylinder inner peripheral surface 40. It has two rails, and its contact surface width D is 0.15 to 0.3 mm.
[0014]
(3) A wear-resistant film is formed on the rail outer peripheral surface of (1) or (2) by PVD (Physical Vapor Deposition physical vapor deposition) or CVD (Chemical Vapor Deposition chemical vapor deposition). However, for (2), this film is formed as necessary.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In the oil ring as the first embodiment of the present invention, as shown in FIG. 1, a single rail 11 protruding in the direction of enlarging the diameter of the ring is formed at the center of the outer peripheral surface of the oil ring body 10. And the cross-sectional shape of the front-end | tip part of the rail 11 is formed in contact with the contact surface 14 parallel to the inner peripheral surface 40 of the cylinder and above the contact surface 14, and the ring diameter is expanded downward from above. The shape has a tapered surface 15.
If comprised in this way, since the climbing effect | action with respect to the oil of the front-end | tip part of the rail 11 improves by the effect | action of the taper surface 15 in the raising process of a piston, oil will not be pushed back to the 2nd ring side in large quantities. Further, as a result of providing only one rail 11, the surface pressure of the sliding surface (contact surface 14) is increased, so that the oil scraping action during the downward stroke of the piston is increased, and the amount of lubricating oil consumption is reduced. Can be reduced.
[0016]
In the oil ring as the second embodiment of the present invention, as shown in FIG. 2, one rail 11 protruding in the direction of enlarging the diameter of the ring is formed at the center of the outer peripheral surface of the oil ring main body 10. And let the cross-sectional shape of the front-end | tip part of the rail 11 be a shape which has the contact surface 16 which perimeter | circulates in parallel with the internal peripheral surface 40 of a cylinder. And the contact surface width D in the front-end | tip part of the rail 11 shall be 0.15-0.3 mm.
With this configuration, it is possible to obtain a high sliding surface pressure that cannot be obtained with a conventional product having two rails while maintaining a practically sufficient rail strength. it can.
[0017]
In these embodiments, by providing only one rail 11 at the center of the oil ring main body 10, symmetry is obtained with respect to the center line of the oil ring main body 10, so that when rolling from a wire to this shape, This eliminates the twist and eliminates manufacturing problems.
[0018]
Further, in the conventional oil ring having the two rails 11a and 11b, the return holes (windows) 13 for the purpose of relaxing the pressure of the oil accumulated between the rails 11a and 11b and returning the oil to the crankcase are provided between the rails. However, in the oil ring 10 having only one rail 11 as in the embodiment of the present invention, there is no need to provide a return hole. Therefore, the cost can be reduced. Further, in the oil ring main body 10, since there is no difference in strength between the window portion 13 and other portions, it is advantageous in terms of processing.
[0019]
Furthermore, in another embodiment of the present invention, a hard film is formed at least on the tip of the rail 11 of the oil ring body 10 by PVD or CVD, so that the shape is preserved and the sliding surface pressure is reduced. Retained.
[0020]
【Example】
The inventors arrived at the idea of the oil ring of the present invention shown in FIGS. 1 and 2 from the analysis of the experimental results as shown below.
The prototype of the oil ring used for the experiment was an I-type oil ring, and the rail tip shape and dimensions were adjusted as follows.
[0021]
(1) Experiment 1: Comparison of oil consumption of an oil ring having one rail and an oil ring having two rails (the dimensions of the test oil ring are shown in FIG. 4).
<Experimental specimen>
(1) One-rail product (a product obtained by grinding the lower rail of a two-rail product): As shown in FIG.
Contact width D 0.23mm
Upper and lower rail step E 0.6mm
Number of rails 1 surface pressure 3668kPa
(2) Two-rail product: As shown in FIG.
Contact width D 0.23mm
Number of rails 2 Surface pressure 3675kPa
<Experimental conditions>
Engine speed 4000rpm Load Full load [0022]
(2) Experiment 2: Comparison of oil consumption between an oil ring having a tapered rail and an oil ring without a taper (the dimensions of the test oil ring are shown in FIG. 5).
<Experimental specimen>
(1) Tapered rail product: as shown in FIG.
Contact width B 0.2mm
Taper width C 0.2mm
Taper angle 2 °
Number of rails 2 Surface pressure 3600kPa
(2) Non-tapered product (conventional I type): As shown in FIG.
Contact width D 0.2mm
Number of rails 2 Surface pressure 3600kPa
<Experimental conditions>
Engine speed 4000rpm Load Full load [0023]
(3) Results of Experiment 1 As shown in FIG. 6, the ratio of the oil consumption of the one-rail product and the two-rail product was 1: 0.94, and the oil consumption was almost the same level.
[0024]
(4) Results of Experiment 2 As shown in FIG. 7, the ratio of oil consumption between the tapered product and the non-tapered product was 0.71: 1.
[0025]
Therefore, from the experimental results, if a single rail is used, a high surface pressure can be secured by reducing the contact area without sacrificing the rigidity of the rail, and the taper surface is provided above the contact surface. As a result, the action of riding on the oil film formed between the cylinder inner periphery and the oil ring outer peripheral surface works, and the pumping up of oil to the piston land is reduced. Therefore, it can be expected to realize an oil ring that reduces the consumption of lubricating oil. This is the oil ring of the present invention shown in FIG.
[0026]
Further, the empirical knowledge described below has led to the idea of the oil ring of the present invention as shown in FIG.
The oil ring body is formed by several rolling and annealing processes, but as a manufacturing limit, it has been found that the lower limit of the contact width D in the completed state of the rail is about 0.15 mm. Therefore, the minimum total width per two-rail product is 0.30 mm, and a single-rail product larger than 0.30 mm has the advantage of higher contact pressure than the two-rail product. Since it cannot be claimed, the upper limit value of the hitting width of one rail product can be regarded as 0.30 mm.
[0027]
When the oil ring of the present invention is used, it is desirable to combine it with a piston 30 having a plurality of oil return passages 32 as shown in FIG.
[0028]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the combination oil ring which can reduce lubricating oil consumption can be implement | achieved by suppressing oil scooping up action or increasing oil scooping up action.
[Brief description of the drawings]
1A and 1B are cross-sectional views of an oil ring as a first embodiment of the present invention, in which FIG. 1A is a state engaged with a cylinder, and FIG.
FIG. 2 is a cross-sectional view showing a state in which an oil ring as a second embodiment of the present invention is combined with a piston and a cylinder.
FIG. 3 is a cross-sectional view of an oil ring of one rail in the prior art.
FIGS. 4A and 4B are cross-sectional views showing an I-type oil ring used in Experiment 1, wherein FIG. 4A is a two-rail product and FIG. 4B is a one-rail product.
FIGS. 5A and 5B are cross-sectional views showing an I-type oil ring used in Experiment 2, wherein FIG. 5A is a non-tapered oil ring, and FIG. 5B is a tapered oil ring.
6 is a diagram showing the results of Experiment 1. FIG.
7 is a diagram showing the results of Experiment 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Oil ring main body 11, 11a, 11b ... Rail 12 ... Web 13 ... Oil window 14, 16 ... Contact surface 15 ... Taper surface 20 ... Expander 30 ... Piston 31 ... Ring groove surface 32 ... Oil return path 40 ... In cylinder Peripheral surfaces B, D ... Contact surface width C ... Tapered surface vertical width

Claims (3)

In the two-piece type combined oil ring comprising an oil ring main body (10) and an expander (20) for pressing the oil ring main body (10) from the inner peripheral side to the outer peripheral side radial direction, the oil ring main body (10) Is substantially symmetrical with respect to the center line of the oil ring body, and has one rail (11) protruding so as to enlarge the diameter of the ring at the center of the outer peripheral surface of the oil ring body (10), The rail tip includes a contact surface (14) parallel to the cylinder inner peripheral surface (40), and a tapered surface (15) arranged continuously above the contact surface and expanding the ring diameter downward from above. And a combined oil ring characterized by not having an oil return window (13). In the two-piece type combined oil ring comprising an oil ring main body (10) and an expander (20) for pressing the oil ring main body (10) from the inner peripheral side to the outer peripheral side radial direction, the oil ring main body (10) Is substantially symmetrical with respect to the center line of the oil ring body, and has one rail (11) protruding so as to enlarge the diameter of the ring at the center of the outer peripheral surface of the oil ring body (10), The rail tip has only a contact surface (16) parallel to the cylinder inner peripheral surface (40), the contact surface width (D) is 0.15 to 0.3 mm, and the oil return window (13 A combined oil ring characterized by having no).   The combined oil ring according to any one of claims 1 and 2, wherein a wear-resistant film by PVD or CVD is formed at least on the rail tip.

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