JP2009228694A - V-shaped oil ring and wire rod - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ring use wire rod into which oil holes can easily be bored by machining and that leads to the improvement of fuel efficiency by reducing a total weight, in the advancement of narrowing the space between rails in an oil ring. <P>SOLUTION: The vertical cross section to the longitudinal direction of an oil ring use wire rod has a roughly V shape. The oil holes can be bored by machining, by partially removing an angle part 4 formed by the letter of V, and using a self expansion force by the elasticity of the roughly V shape, oil scraping by proper contact pressure becomes possible with no need of a spacer or a coil expander, which are conventionally required. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an oil ring used in a piston mechanism.

A reciprocating engine such as an automobile has a piston. In many cases, the piston has three rings. The piston reciprocates thousands of times per minute, and the associated piston ring is used under very harsh conditions. Therefore, high quality is required in various items such as strength and wear resistance.

One of the three types of piston rings is an oil ring. The oil ring is farthest from the combustion chamber and its role is to scrape off excess oil adhering to the cylinder wall. Two types of oil rings are widely used: a three-piece type and a two-piece type.

The three-piece type consists of two wires (called side rails) whose cross section is a flat wire or a substantially elliptical shape and a metal fitting (called a spacer) for providing a gap between the rings. Say something combined. This is described in Patent Document 1. The 3-piece type has independent side rails that scrape off oil, so it has good follow-up to the reciprocating motion of the piston.

The two-piece type means a combination of a ring (called an integral ring) having a substantially I-shaped cross section and a coil expander. This is described in Patent Document 2. The integral ring is obtained by coiling a deformed wire having a substantially I-shaped cross section by rolling a wire having a circular or square cross section. There are two points in sliding contact with the cylinder wall (referred to as rail portions). Scrape off excess oil from the cylinder wall at the rail. Moreover, the thin-walled part (called a web part) located between the rails has an oil hole. There are two methods for providing the oil holes: punching with a press or the like, and recently melting with a laser (Patent Document 3). The oil holes are provided in series at regular intervals on the circumference. The purpose of the oil hole is to allow the oil that has been scraped off to not enter the space surrounded by the cylinder wall, the two rail parts, and the web part, but escape into the piston. The two-piece type has high strength and excellent oil adjustment function and is widely used.

The coil expander is a ring-shaped spring. The reason why the coil expander is required is that the integral ring is expanded so as to expand in the radial direction and is always in sliding contact with the cylinder wall with an appropriate pressure.

However, the three-piece type and the two-piece type have the following problems.

As the name suggests, the three-piece type consists of three parts, each of which is independent, so the initial oil scraping is very good. However, sludge generated during continuous use adheres and the initial assembled shape cannot be maintained. For this reason, there is a tendency to use a two-piece type oil ring from the viewpoint of fuel consumption.

In the two-piece form, the integral ring has a very complex and sophisticated shape. High Cr martensitic stainless steel, which is difficult to process, is used as a material from the viewpoint of heat resistance and erosion resistance. In order to manufacture this shape, it is necessary to perform rolling several times, and high accuracy is required. For this reason, the conditions for production are severe, and cracking is very likely to occur. In order not to cause cracks, rolling must be performed little by little, but productivity is very poor.

In addition, the I-type has become increasingly thinner in recent years. This makes it increasingly difficult to create shapes. In particular, since the distance between the rails has been reduced, it has become difficult to punch holes in the web portion, resulting in increased occurrence of defects and further deteriorated productivity.

In order to overcome the punching method, a method of melting by a laser has been studied. However, since strict dimensional accuracy is required, positioning is difficult and it takes time to melt. In order to solve these problems and increase productivity, the productivity is improved by providing a plurality of laser irradiation machines. However, it is not realistic because the capital investment and the subsequent maintenance costs become very large. Further, since the peripheral portion provided with the oil holes is subjected to thermal alteration by the laser, there is a disadvantage that the strength is extremely weak compared with the portion where the holes are not perforated.

Moreover, an attached elastic body is required in common for the three-piece type and the two-piece type. Neither the 3-piece type spacer nor the 2-piece type coil expander is directly related to the intended function of the oil ring. This is additionally required in order to adjust the oil amount of the cylinder wall, which is the original purpose. However, when the piston holds these assemblies and moves the piston at a speed of several thousand times / minute, extra energy is required. In other words, the energy conversion efficiency is deteriorated, and the fuel consumption of the engine or the automobile is extremely lowered.
JP 58-137665 A JP 61-45172 JP2007-278401

Therefore, we will provide an oil ring wire and an oil ring that can cope with further thinning in the future and improve fuel efficiency by reducing the total weight.

The inventor considered the following two points. 1. Even if it is thin, oil holes should be provided by machining such as continuous punching or cutting. 2. To improve fuel efficiency, the total weight of the oil ring should be light. As a result of trial and error of a structure that can be achieved with respect to these two points, it was discovered that the cross-section is V-shaped, and as a result of diligent efforts, a completely new type of piston ring could be manufactured.

That is, an oil ring wire having a substantially V-shaped cross section perpendicular to the longitudinal direction has been invented.

In order to implement the present invention, it is desired that the material is an oil ring wire made of a material having superelastic characteristics.

More preferably, the material is an oil ring wire made of a titanium alloy.

Also, this invention product has oil holes arranged in series at regular intervals in the longitudinal direction as in the prior art.

By ring-molding using the wire as described above, an oil ring that solves the two problems of punching and improving fuel consumption can be obtained. Hereinafter, this product of the present invention is referred to as a V-shaped (oil) ring.

The function of the V-shaped ring will be described with reference to FIG. The V-shaped ring has two wing portions 3 due to its shape, and is composed of an angle portion 4 formed by the two wing portions 3. Both ends of the wing portion 3 correspond to I-shaped rail portions, which are in sliding contact with the cylinder wall and scrape off unnecessary oil. When this ring is set on the piston, a force is applied in the direction of pushing into the V groove 6 of the piston, so that the angle formed by both wing portions 3 is narrowed. When the cylinder is set, the pushing force is removed, so that the force to return to the original shape, that is, the V shape is restored. This is the force that the ring tries to expand.

In order for the V-shaped ring to have a self-expanding force, the material for producing the V-shaped ring must be excellent in elasticity that is difficult to plastically deform. For example, a shape memory alloy is preferable. In addition, as a fundamental characteristic that matches the usage conditions of the piston ring, it must be excellent in wear resistance and strength.

In the present invention, a Ti alloy is suitable as a typical example. Ti alloys have been used in various ways. By blending the alloy elements, the properties can be changed for various applications. Therefore, elasticity, wear resistance, strength, etc. can be achieved by adjusting the content of each alloy element according to the specifications of the reciprocating engine.

In order to apply the invention to a piston, it must have a V-shaped groove on the piston circumference. Further, the V-groove 6 must have an acute angle than the angle formed by the wing portion 3. The reason will be described again with reference to FIG. When a force is applied to the center of the piston 7 over the entire circumference to push the V-shaped ring into the groove, the V-shape is narrowed along the angle of the V-shaped groove 6 of the piston ring. When the pushing force is removed, the ring expands due to the narrowed V-shaped restoring force, and a force is exerted to exit the groove. In actual use, this is a force with which the ring slides against the cylinder wall 8. Due to the self-elastic force to expand the ring, an accessory such as a coil expander is not required as in the prior art.

In the above-described state, it is desirable that the pressure inlet 5 of the V groove 6 of the piston has an R shape or the like so that the ring can be easily expanded by the self-elastic force. Under the situation where the piston reciprocates, a force may act in a direction in which the ring receiving pressure from the cylinder wall is pushed into the cylinder groove. When the pressure inlet is angular, the wing portion 3 bites in or wears locally. By making the pressure inlet into an R shape or the like, the V-shaped ring can be smoothly expanded and pressed.

As a method of manufacturing a wire having a substantially V-shaped cross section, there is a rolling method. However, the method is not limited to this method. As a rolling method, Turks roller rolling is preferable. Combine several types of rollers and pass the prepared general wire through a special hole surrounded by the rollers. The cross section of the material that has passed between the rollers has a shape of an odd-shaped hole, and undergoes plastic deformation step by step to a substantially V shape. As is apparent from the shape, the profile processing to the substantially V shape is much easier than the I shape, and the number of processes can be greatly reduced.

The cross-sectional shape need not be a complete V shape. As shown in FIG. 2, the cross-sectional shape may be formed such that the wing portion is bent at the pressure inlet and the rail portion is perpendicular to the cylinder wall. Further, the inner side of the angle portion may be sharp or may have an R shape, but an R shape in which stress is easily dispersed is preferable because expansion and press-fitting are always repeated.

Moreover, it is not difficult to open the oil through hole in the ring wire. In the V-shaped ring, the angle 4 can be manufactured by machining. Even in the case of a ring having a width of 1 mm or less, which has been difficult with the conventional I shape, the oil through hole can be reliably opened.

Various methods are conceivable. For example, a grinding method will be described with reference to FIG. The wire is sent to the processing part for a certain length and stops. Grinding is performed by pressing a grinding machine that rotates the grindstone against the angle portion 4. At this time, it must be ground to the depth of penetration. After grinding, the grinder returns to its original position and the wire is sent. Thus, the oil hole can be continuously provided by repeating the feeding and cutting of the wire. As another method, punching cut by a char cutter may be used instead of the grinding machine. Any other method is not limited.

Further, the step of providing the oil hole may be performed at the time of ring formation. When ring processing is performed after the oil hole is provided, the strength of the oil hole portion is weakened and, strictly speaking, a regular polygon is formed. Therefore, when ring processing is performed from a wire having an oil hole, it is necessary to devise such that a portion having no oil hole has an R shape. However, if the above-described perforating process is performed after the ring process, the shape is not lost during the ring molding.

The ring surface, in particular the wing part 3 in contact with the rail part 2 and the pressure inlet 5, requires a surface hardening treatment. In addition to hardening by heat treatment, nitriding treatment, shot peening method, laser and electron beam quenching, and other conventional surface hardening treatments such as PVD and diamond-like carbon treatment (DLC) It is good to use for.

By using the product of the present invention as described above, the self-expanding force due to the substantially V-shaped elasticity can be used, so that the fuel efficiency of the engine is significantly increased by eliminating the spacers and coil expanders that have been required in the past. In addition, since it is possible to cope with drilling even in the thinner width between rails in the future, a great effect is brought about.

A titanium alloy wire whose cross section having a wire diameter of φ0.8 mm is substantially circular is prepared, and cold-rolled to obtain the shape shown in FIG. In order to obtain this shape, rolling is performed gradually in about 10 times. In the first few rolls, rolling is carried out on a flat surface by a tandem roll. Next, the turks roller is assembled and rolled from above, below, left and right, and rolling is planned so as to gradually form a V-shape. Since work hardening occurs in the middle, heat treatment is appropriately performed.

As described above, drilling is sequentially performed using a grinding machine with a grindstone. The maximum number of oil holes that can be opened at one time was 10 for the best accuracy. Thus, an oil ring wire is obtained.

Typical example of cross section of the wire of the present invention Other typical examples of the cross section of the wire of the present invention Cross section of piston using the present invention Wire of the present invention Example of drilling method for wire of the present invention Conventional 3-piece oil ring Conventional two-piece oil ring

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 V-shaped ring 2 Rail part 3 Wing part 4 Angle part 5 Pressure inlet 6 V groove 7 Piston 8 Cylinder wall 9 Oil hole 10 Wire rod 11 Grinding machine 12 Grinding wheel

Claims (6)

Oil ring wire having a substantially V-shaped cross section perpendicular to the longitudinal direction The oil ring wire according to claim 1, wherein the material is made of a material having superelastic characteristics. The wire for an oil ring according to claim 1 or 2, wherein the material is made of a titanium alloy. The wire for oil rings according to any one of claims 1 to 3, which has oil holes arranged in series at regular intervals in the longitudinal direction. An oil ring using the oil ring wire according to any one of claims 1 to 4. The oil ring according to claim 5, wherein a surface treatment for wear resistance is applied to a part sliding with the cylinder or the whole.