JP2005320934A - Reciprocatingly moving member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reciprocatingly moving member formed simply at low cost and capable of well maintaining lubricating properties over a long period from its early stage. <P>SOLUTION: A solid lubricating film of a prescribed pattern is formed by a printing method. The solid lubricating film comprises presence portions A (projected portion) having the solid lubricating film within the prescribed area of a piston skirt part 10 and non-presence portions B (recessed portion) having no solid lubricating film and allowing a lubricating oil to be held in the non-presence portions B present between the presence portions A. Since the lubricating oil can be well held in the non-presence portions B, the reciprocatingly moving member simply formed at low cost and capable of maintaining the lubrication properties over a long period from its early stage can be provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reciprocating member such as a piston that slides with respect to other components in a reciprocating device such as an internal combustion engine, an air compressor, or a plunger.

  A piston used for an internal combustion engine or the like will be described as an example of a reciprocating member. The piston is fitted into a cylindrical cylinder liner via a piston ring held in a piston ring groove formed around the piston. The piston is connected to the crankshaft via a piston pin and a connecting rod, so that motion conversion is performed between the reciprocating motion of the piston and the rotational motion of the crankshaft.

  In addition, there is lubricating oil between the piston ring and the cylinder liner, and between the piston skirt and the cylinder liner that swings around the piston pin, and the lubricating oil provides good lubrication between the two, Scuffing (welding) and friction are suppressed, and friction is reduced.

  Here, in addition to improving the lubrication characteristics between the piston ring and the cylinder liner, in the compression stroke and the combustion stroke for compressing the air in the cylinder, pressure acts from the upper surface side of the piston, while depending on the crank angle. Since the connecting rod connected to the piston is inclined with respect to the cylinder central axis in the reciprocating motion direction, a side pressure is generated that presses the piston toward the inner wall of the cylinder liner due to the balance of force, thereby causing the skirt portion of the piston to move. Since it is pressed against the cylinder liner and reciprocated, it improves the lubrication characteristics between the piston skirt and cylinder liner, and prevents scuffing (welding) between the piston skirt and cylinder liner. In addition, it suppresses wear over a long period of time and reduces friction. It is also important.

  For this reason, conventionally, as in Patent Document 1, the piston skirt is coated with a solid lubricant so as to improve the lubrication characteristics between the piston skirt and the cylinder liner. There is.

  However, as in Patent Document 1, when a polyimide resin is used as a binding, although initial conformability is high, wear resistance is low, so wear progresses after a predetermined time of operation, and piston base material (aluminum alloy). Therefore, it was difficult to maintain high lubrication characteristics over a long period of time. In addition, since the lubricating oil is released from between the piston skirt and the cylinder liner after being left for a long period of time, there is insufficient lubrication between the piston skirt and the cylinder liner at the start after being left for a long period of time. This solution was difficult even if the solid lubricant was coated on the piston skirt.

  For this reason, in order to improve the retention characteristics of the lubricating oil, as in Patent Document 2, a streak extending in the circumferential direction of the outer peripheral surface is formed by machining on the outer peripheral surface of the piston skirt, There is one in which a solid lubricating film is formed thereon. In some cases, a solid lubricant film is coated on the entire surface of the skirt portion and then cut by machining to form a streak.

However, these products have a problem that the manufacturing cost increases because the manufacturing of the piston is complicated. In addition, due to the limitations of the processing method, the shape of the streak is limited and there is a problem that the degree of design freedom is low.
JP-A-54-162014 JP 2001-279495 A

  The present invention has been made in view of the above-described conventional situation, and provides a reciprocating member (for example, a piston) capable of maintaining good lubrication characteristics from the initial stage over a long period of time while having a simple and inexpensive configuration. The purpose is to do.

In order to achieve the above object, a reciprocating member according to the invention described in claim 1 is:
By applying a solid lubricant to a predetermined range of a reciprocating sliding surface of a reciprocating member that reciprocates in an environment where lubricating oil is present, a convex portion present in a convex shape and a concave portion present in a concave shape And the lubricating oil is held in the concave portions existing between the convex portions.
The application of the fixed lubricant can be performed by a printing method.

Further, like the reciprocating member according to the third aspect of the present invention, the solid lubricant is applied to the predetermined range of the reciprocating sliding surface of the reciprocating member that reciprocates by the printing method, thereby forming a convex shape. A convex portion that exists and a concave portion that exists in a concave shape are provided.
The printing method may be a screen printing method or a pad printing method.
The concave portion may be a non-existing portion that does not form a solid lubricating film and does not have a solid lubricating film.

  By the way, when the reciprocating member is disposed in the main body device (internal combustion engine when the reciprocating member is a piston) and actually used, at least in the direction of gravity, the convex portion, the concave portion, It is preferable that the solid lubricant film is formed in a pattern in which, and are alternately present.

  The present invention applies a solid lubricant to a predetermined range of a reciprocating sliding surface (such as a skirt portion of a piston) of a reciprocating member such as a piston, thereby presenting a convex portion present in a convex shape and a concave shape. In addition, the lubricating oil is retained in the concave portions existing between the convex portions, so that the lubrication characteristics are maintained well from the beginning for a long period of time while having a simple and inexpensive configuration. Therefore, both suppression of scuffing and improvement of wear resistance can be achieved at a high level. That is, according to the present invention, it is possible to provide a reciprocating member capable of maintaining a good lubrication characteristic from the initial stage over a long period of time while having a simple and inexpensive configuration.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIGS. 1 and 2, a piston 1 as a reciprocating member according to an embodiment of the present invention has a valve recess for avoiding interference with a valve disposed on a cylinder head on a piston top surface 2. 3, a top land 4, a top ring groove 5, a second land 6, a second ring groove 7, a third land 8, and an oil ring groove 9 are provided on the side surface of the piston, and a piston skirt portion is provided under the oil ring groove 9. 10 is provided. Further, a piston pin hole 12 for inserting and holding a piston pin (not shown) that is rotatably inserted into a small end portion of a connecting rod (not shown) connected to a crankshaft (not shown) includes a pin boss. The part 11 is opened substantially parallel to the longitudinal direction of the crankshaft. The piston 1 is made of, for example, a Si-based aluminum alloy (AC8A or the like), but may be made of other materials.

  In this embodiment, as shown in FIGS. 1 and 2, a solid lubricating film having a predetermined pattern is formed (applied) on the hatched portion of the piston skirt portion 10 by, for example, a printing method. More specifically, the solid lubricating coating is made by dispersing lubricating components such as molybdenum disulfide, tungsten disulfide, graphite, PTFE, boron nitride, cluster diamond, and silicon alone or in combination with various resins using a solvent or water. In this embodiment, the solid lubricant film is formed by applying the solid lubricant film to a necessary portion of the piston skirt portion 10 by a printing method such as a silk printing method or a pad printing method.

  For silk printing, for example, a plate (screen) having a stitch shape such as silk is used, and the paint or ink-like substance is placed on the plate, and the paint or ink-like substance is applied from the stitch of the screen. This is a printing method in which coating is carried out by passing a film. Also, in pad printing, the paint or ink-like material ink is poured into a plate engraved in a predetermined shape, copied onto the pad, and further pressed against the surface of the molded product (here, the piston skirt portion 10). This is a printing method in which the paint or ink-like substance is transferred to a molded product.

  Here, as a specific example of the predetermined pattern of the solid lubricant film to be formed, there are various patterns depending on the required lubrication characteristics as shown in FIGS. 3 (A) to (C) and FIGS. 4 (A) to (C). Patterns can be employed.

  In the present embodiment, the existence portion A where the solid lubricant film exists within a predetermined range of the piston skirt portion 10 (a portion that is convex by a film thickness of about several μm to several tens of μm. Dimensions in the width direction. Is, for example, about 0.1 to 1 mm) and a non-existing portion B where no solid lubricating film is present (a portion which is concave by the film thickness of the existing portion A of about several μm to several tens of μm. The dimension in the width direction is For example, about 3 to 5 times the width of the existing portion A), and a non-existing portion B existing between the existing portions A can hold a lubricating oil in a predetermined pattern. Is formed by a printing method, and thereby the following effects can be obtained.

That is,
(1) The existence portion A where the solid lubricating film is present improves the lubrication characteristics between the piston skirt portion 10 and a cylinder liner (not shown), improves the familiarity between the piston skirt portion 10 and the cylinder liner, and improves scuffing. The generation of oil is effectively suppressed, and a relatively large amount of lubricating oil is retained by the non-existing portion B where no solid lubricating coating is present, and the large amount of lubricating oil is effectively supplied to the existing portion A to resist Abrasion can be improved and friction can be reduced.

  Further, since the minute scuff generated in the existing portion A can be cut off in the non-existing portion B, it is possible to effectively suppress the expansion of scuffing.

  Since the existence portion A and the non-existence portion B are mixed, the contact area between the piston skirt portion 10 and the cylinder liner is substantially reduced, so that the hydraulic pressure (surface) generated between the existence portion A and the cylinder liner is reduced. Pressure) can be substantially increased, so that the possibility that the existing portion A and the cylinder liner are in direct contact with each other can be suppressed as compared with the conventional case. For this reason, the scuffing resistance and wear resistance can be improved.

  (2) Further, since the lubricating oil is held in the non-existing portion B, the lubricating oil can be held well between the piston skirt portion 10 and the cylinder liner. In place of a solid lubricating coating (for example, molybdenum disulfide or graphite) having low wear resistance, a fixed lubricating coating (for example, PTFE) having poor lubricating oil retention but excellent wear resistance may be used. The occurrence of scuffing between the piston skirt portion 10 and the cylinder liner due to the lack of lubricating oil between the piston skirt portion 10 and the cylinder liner at the time of starting after being left for a period can be effectively suppressed. Therefore, it is possible to employ a solid lubricating film that is inferior in lubricating oil retention but excellent in wear resistance, thereby suppressing wear over a long period of time and keeping friction low for a long period of time. It becomes possible.

  In other words, it was necessary to determine the selection and blending of various materials for forming the solid lubricating film so as to improve the retention characteristics of the lubricating oil at the expense of wear resistance. ) And non-existing portions B (concave portions) in which no solid lubricating film is present are alternately present at least in the reciprocating direction, so that the retention characteristics and the wear resistance of the lubricating oil are in a trade-off relationship. It is possible to achieve both at a high level, and thus the degree of freedom in adopting and blending the material for forming the solid lubricating film can be remarkably improved.

  (3) In this embodiment, since the solid lubricating film is formed by using the printing method, the solid lubricating film having a desired pattern can be formed by a simple and inexpensive method.

  In addition, compared to the case of forming streaks by machining (such as cutting), a relatively large cutting force or clamping force does not act on the piston. Adverse effects can also be suppressed. Furthermore, according to the present embodiment, since a solid lubricating film having a predetermined pattern can be formed by batch processing, there is an advantage that manufacturing time can be shortened.

  And since the solid lubricant film can be formed by post-processing on the finished product after finishing machining (cutting, etc.) or after surface treatment (tin-plating, etc.), there is no need to make a major change in the piston manufacturing process. There is also a merit that it is possible to entrust the film forming process to a contractor.

  In addition, since it is only necessary to form a solid lubricant film by post-processing, a piston that does not require the formation of a solid lubricant film (specifications in which the use environment is not strict) and a solid that is common to surface treatments such as machining and plating There is also an advantage that a piston (specification in which the use environment is strict) that requires the formation of a lubricating coating can be manufactured using the same piston manufacturing line.

  The effect of forming the solid lubricant film on the piston skirt in an uneven shape by such a printing method is the reciprocating member of the type that does not interpose the lubricating oil on the sliding surface (to ensure the lubrication characteristics only with the solid lubricant) It can be played in the same way.

  In the present embodiment, the solid lubricant film is formed on the piston skirt portion in a concavo-convex shape by a printing method. However, the present invention is not limited to this. For example, a coating method using spraying using masking or the like or It is also possible to apply a solid lubricating coating material directly to the skirt using an application nozzle or the like to form a predetermined pattern.

  In the above embodiment, the solid lubricating film is not formed in the concave portion. However, the present invention is not limited to this, and the lubricating oil can be held in the concave portion formed between the convex portions. If possible, it is needless to say that a solid lubricating film having a thickness smaller than that of the convex portion may be formed on the concave portion.

  As described above, according to the present embodiment, the predetermined range of the reciprocating sliding surface of the reciprocating member such as the piston includes the convex portion A and the concave portion B, and between the convex portions A. Since the solid lubricating film having a predetermined pattern capable of retaining the lubricating oil in the existing concave portion B is formed by the printing method, the lubrication characteristics can be maintained from the initial stage for a long time while having a simple and inexpensive configuration. Therefore, it is possible to provide a reciprocating member that can be maintained satisfactorily and that can achieve both high levels of suppression of scuffing and improvement of wear resistance. That is, according to the present embodiment, it is possible to provide a reciprocating member that can maintain the lubrication characteristics satisfactorily from the initial stage for a long period of time while having a simple and inexpensive configuration.

  3A to 3C and FIGS. 4A to 4C exemplify the predetermined pattern of the solid lubricant film, but the present invention is not limited to this, and may be appropriately selected according to required characteristics. Of course, it can be changed.

  By the way, in this embodiment, a piston used as an example of a reciprocating member for an internal combustion engine has been described as an example. However, the present invention can also be applied to a piston used for an air compressor, for example.

  Furthermore, the present invention can also be applied to a sliding surface of a reciprocating member (plunger) of a plunger valve for switching a fluid passage.

  The present invention can also be applied to a sliding surface of a plunger (for example, a reciprocating member such as a fuel pump) for delivering a liquid. In this case, it is a generally known matter that the delivered fuel functions as lubricating oil between the plunger and the cylinder.

  Here, when the reciprocating direction of the reciprocating member matches the direction of gravity when the reciprocating member is actually used, the predetermined pattern of the fixed lubricating film is at least in the reciprocating direction (gravity direction). In this pattern, the existence portion A (convex portion) where the solid lubricant film exists and the non-existence portion B (concave portion) exist alternately. Further, when the reciprocating direction of the reciprocating member does not coincide with the direction of gravity when the reciprocating member is actually used, at least the existing portion A where the solid lubricant film exists in the reciprocating direction and the gravitational direction. And the non-existing portions B are preferably made into a pattern in which they exist alternately.

It is a perspective view which shows the external appearance of the piston as a reciprocating member based on one embodiment of this invention. It is the figure which looked at the piston same as the above from the X direction of FIG. (A), (B), (C) is a figure which shows an example of the pattern of the solid lubricant film formed in the piston skirt part (sliding surface of a reciprocating member), respectively. (A), (B), (C) is a figure which shows an example of the pattern of the solid lubricant film formed in the piston skirt part (sliding surface of a reciprocating member), respectively.

Explanation of symbols

1 piston (equivalent to reciprocating member)
10 Piston skirt (equivalent to sliding surface)
A Solid lubricant coating existing part (convex part)
B Non-existing part of solid lubricating coating (concave part)

Claims (7)

  By applying a solid lubricant to a predetermined range of a reciprocating sliding surface of a reciprocating member that reciprocates in an environment where lubricating oil is present, a convex portion present in a convex shape and a concave portion present in a concave shape A reciprocating member characterized in that lubricating oil is held in a concave portion existing between the convex portions.   The reciprocating member according to claim 1, wherein the fixed lubricant is applied by a printing method.   By applying a solid lubricant by a printing method to a predetermined range of the reciprocating sliding surface of the reciprocating member that reciprocates, a convex portion that exists in a convex shape and a concave portion that exists in a concave shape are provided. A reciprocating member characterized by that.   The reciprocating member according to claim 2 or 3, wherein the printing method is a screen printing method or a pad printing method.   The reciprocating member according to any one of claims 1 to 4, wherein the concave portion is a non-existing portion where a solid lubricating film is not formed and a solid lubricating film is not present.   The solid lubricant film is formed in a pattern in which the convex portions and the concave portions are alternately present at least in the direction of gravity when the reciprocating member is used. The reciprocating member according to any one of 5. The reciprocating member according to any one of claims 1 to 6, wherein the reciprocating member is a piston of an internal combustion engine, and the reciprocating sliding surface is a skirt portion of the piston.

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