JP2000274352A - Reciprocation type compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the connecting part of a piston pin with a connecting rod from being abnormally worn out in a reciprocation type compressor. SOLUTION: At the connecting part of a connecting rod 5 with a piston pin 13, since the connecting rod 5 plays a rocking motion relative to the fixed piston pin 13, a fluid film due to lubricant is hardly formed up, and metals are brought into contact with each other at a part of a sliding surface. At this time, the sliding of a non-coagulant film 14 formed over the surface of the piston pin 13 with the metallic contact part of a connection portion of the connecting rod 5, prevents aluminum forming the connecting rod 5 from being coagulated onto the piston pin 13. As a result, an increase in temperature around the connecting part of the connecting rod 5 with the piston pin 13 is reduced, and restraining lubricant from being removed from the surface thereby prevents the surface from being moved to a dry and frictional condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the durability of a piston pin portion of a reciprocating compressor such as a refrigerator compressor of a refrigerator.

[0002]

2. Description of the Related Art Conventionally, as a means for improving the durability of a piston pin portion of a reciprocating compressor, a method of forming a wear-resistant coating on the surface of a piston pin has been proposed in Japanese Utility Model Laid-Open No. 61-149.
No. 783, and the like.

[0003] The features of a conventional reciprocating compressor will be described below with reference to the drawings.

FIG. 7 is a sectional view of a conventional reciprocating compressor. 7, reference numeral 1 denotes a crankshaft connected to a drive source (not shown), 2 denotes a piston reciprocating in a cylinder (not shown), 3 denotes a steel piston pin fixed to the piston 2, and 4 denotes a piston pin. The wear-resistant coating formed on the surface of the piston pin 3 by the nitriding treatment.
And a connecting rod for connecting the piston pin 3 to the connecting rod. The connecting rod 5 is formed of an aluminum alloy for weight reduction.

Next, the operation will be described. The motion of the crankshaft 1 eccentrically rotated by the drive source is transmitted to the piston 2 via the connecting rod 5 and the piston pin 3, and the piston 2 reciprocates to compress gas such as refrigerant. At this time, the compressive load applied to the piston 2 is applied to the piston pin 3 with the connecting rod 5 interposed therebetween.
And the crankshaft 1 act so as to push each other.

At the connection between the connecting rod 5 and the crankshaft 1, the crankshaft 1 rotates and is mainly fluid-lubricated with lubricating oil (not shown). On the other hand, at the connecting portion between the connecting rod 5 and the piston pin 3, the connecting rod 5 swings with respect to the fixed piston pin 3, so that a fluid film is not easily formed by the lubricating oil, and the rotation direction is particularly reversed. At this time, it stops for a moment and metal contact occurs on a part of the sliding surface. At this time, the sliding of the wear-resistant coating 4 made of iron nitride formed on the surface of the piston pin 3 and the connecting portion of the connecting rod 5 suppresses transition to abnormal wear such as adhesion.

[0007]

However, in the above-mentioned conventional construction, in the case of a connecting rod made of an aluminum alloy, which has a low melting point and is easily adhered, when a metal contact occurs at a connecting portion with a piston pin, the sliding heat generates a metal. As the temperature around the contact portion rises, the molten aluminum adheres to the wear-resistant coating, and the sliding state at the connecting portion develops severe adhesion wear between the aluminum members.

As a result, the friction coefficient increases and the surrounding temperature further increases, so that the lubricating oil supplied to the connecting portion cannot be adsorbed on the sliding surface, and the connecting portion between the wear-resistant coating and the connecting rod is completely formed. Then, dry friction occurs, and abnormal wear occurs beyond the limit of the wear-resistant coating. Therefore, there is a demand for a method of reducing a rise in temperature of a connecting portion between a connecting rod and a piston pin, suppressing desorption of lubricating oil from a sliding surface, and preventing a transition to a dry friction state.

It is an object of the present invention to prevent such a connecting portion between the connecting rod and the piston pin from shifting to a dry friction state.

[0010]

Therefore, a reciprocating compressor according to the present invention has a piston pin formed on a surface of a piston shaft on a crankshaft side with a film which is non-adhesive to an aluminum material.

According to the present invention, by keeping the friction coefficient of the metal contact portion of the connecting portion between the connecting rod and the piston pin low, the temperature rise is reduced, the separation of the lubricating oil from the sliding surface is suppressed, and the dry friction is reduced. The transition to the state can be prevented.

Further, the lubricating film is formed to have a thickness of 0.1 mm around the crankshaft side surface of the piston pin to which a compressive load is applied.
By forming as thin as 10 to 10 μm, the desired object can be achieved while suppressing an increase in the dimension of the connecting portion between the connecting rod and the piston pin and a change in clearance due to the formation of the non-adhesive film.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An invention according to claim 1 of the present invention is directed to a reciprocating compressor in which a piston compresses while reciprocating in a cylinder, wherein the crankshaft connected to a drive source and the piston are fixed to the piston. A steel piston pin, a non-adhesive coating having a thickness of 0.1 to 10 μm formed on the surface of the piston pin on the crankshaft side,
A reciprocating compressor including a connecting rod made of an aluminum alloy for connecting the crankshaft and the piston pin, and a lubricating oil for lubricating each sliding portion, wherein friction of a metal contact portion of a connecting portion between the connecting rod and the piston pin is provided. Keeping the coefficient low has the effect of reducing the temperature rise, suppressing the release of the lubricating oil from the sliding surface, and preventing the transition to the dry friction state.

Further, the lubricating film is formed to a thickness of 0.1 mm around the crankshaft side surface of the piston pin to which a compressive load is applied.
Forming as thin as 10 to 10 μm can suppress an increase in the dimension of the connecting portion between the connecting rod and the piston pin and a change in clearance due to the formation of the non-adhesive film.

According to a second aspect of the present invention, there is provided a reciprocating compressor according to the first aspect, wherein a non-adhesive film made of a TiALN ceramic film is formed on the surface of the piston pin. Aluminum can be prevented from sticking to the surface of the piston pin even under severe conditions where it melts visually, significantly reducing the temperature rise at the connecting part between the connecting rod and the piston pin, and preventing the lubricating oil from sliding from the sliding surface. It has an effect of suppressing detachment and preventing transition to a dry friction state.

According to a third aspect of the present invention, there is provided the reciprocating compressor according to the first aspect, wherein a non-adhesive film made of a diamond-like carbon film is formed on the surface of the piston pin. It is possible to prevent aluminum from adhering to the piston pin surface even under severe conditions of microscopic melting, and to keep the coefficient of static friction during oscillating motion at about 0.2. It has an effect of remarkably reducing the temperature rise of the connecting portion of the pin, suppressing separation of the lubricating oil from the sliding surface, and preventing transition to a dry friction state.

According to a fourth aspect of the present invention, there is provided a reciprocating compressor according to the first aspect, wherein a non-adhesive film made of a molybdenum disulfide film is formed on the surface of the piston pin. It is possible to prevent aluminum from adhering to the piston pin surface even under severe conditions of microscopic melting, and to keep the coefficient of static friction during oscillating motion at about 0.2. It has an effect of remarkably reducing the temperature rise of the connecting portion of the pin, suppressing separation of the lubricating oil from the sliding surface, and preventing transition to a dry friction state.

Further, the molybdenum disulfide film has a low hardness of Hv 500 or less, and does not make a large difference in hardness even with an inexpensive material having a low base material hardness, and can prevent peeling of the film due to microscopic deformation of the contact portion. it can.

The invention according to claim 5 is characterized in that a lubricating oil containing an alcoholic oiliness improver is used.
Alternatively, the reciprocating compressor according to 4, wherein even after the thin non-adhesive film is worn during the initial run-in wear, the alcohol-based oiliness improver is adsorbed to the steel piston pin base material, and the connecting rod and By keeping the friction coefficient of the metal contact portion of the connecting portion of the piston pin low, the temperature rise is reduced, the lubricating oil is prevented from separating from the sliding surface, and the transition to the dry friction state is prevented.

The invention according to claim 6 uses a lubricating oil containing a carbonate-based oiliness improver.
The reciprocating compressor according to 3 or 4, wherein even after a thin non-adhesive coating has been worn during initial run-in wear,
The carbonate-based oiliness improver is adsorbed on the steel piston pin base material, keeping the friction coefficient of the metal contact part of the connecting part between the connecting rod and the piston pin low, reducing the temperature rise and the sliding surface of the lubricating oil. And has the effect of preventing the transition to the dry friction state.

Further, the carbonate-based oiliness improver has higher polarity and excellent adsorptivity as compared with the alcohol-based oiliness improver, but when the sliding part generates abnormal heat, the carbonate group is decomposed. It has low reactivity and can avoid problems such as corrosive wear.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a sectional view of a reciprocating compressor according to the present invention. In FIG. 1, 1 is a crankshaft connected to a drive source (not shown), 2 is a piston reciprocating in a cylinder (not shown), 13 is a steel piston pin fixed to the piston 2, and 14 is The non-adhesive film 1 μm thick formed on the surface of the piston pin 13 is a connecting rod made of an aluminum alloy connecting the crankshaft 1 and the piston pin 13.

Next, the operation will be described. The motion of the crankshaft 1 eccentrically rotated by the drive source is transmitted to the piston 2 via the connecting rod 5 and the piston pin 13.
And the gas such as the refrigerant is compressed by the piston 2 reciprocating. At this time, the compressive load applied to the piston 2 is applied between the piston pin 1 and the connecting rod 5.
3 and the crankshaft 1 act so as to press against each other.

At the connection between the connecting rod 5 and the crankshaft 1, the crankshaft 1 rotates and is mainly fluid-lubricated with lubricating oil (not shown). On the other hand, connecting rod 5 and piston pin 13
Since the connecting rod 5 oscillates with respect to the fixed piston pin 13 at the connecting portion, the fluid film due to the lubricating oil is not easily formed, and metal contact occurs on a part of the sliding surface.

At this time, the non-adhesive coating 14 formed on the surface of the piston pin 13 and the metal contact portion of the connecting portion of the connecting rod 5 slide, so that the aluminum forming the connecting rod 5 is melted. Even under such severe conditions, the adhesion of aluminum to the surface of the piston pin 13 is prevented. As a result, the temperature rise around the connecting portion between the connecting rod 5 and the piston pin 13 is reduced, the separation of the lubricating oil from the sliding surface is suppressed, and the transition to the dry friction state is prevented.

As described above, in the first embodiment, the non-adhesive film prevents the aluminum forming the connecting rod from adhering to the surface of the piston pin, thereby avoiding the adhesive wear between the aluminum members. Thus, the temperature rise can be reduced, the separation of the lubricating oil from the sliding surface can be suppressed, and the transition to the dry friction state can be prevented. Also, by forming the non-adhesive film as thin as 1 μm around the crankshaft side surface of the piston pin to which a compressive load is applied, the dimension of the connecting portion between the connecting rod and the piston pin is increased due to the formation of the lubricating film. And achieve the intended purpose while suppressing changes in clearance.

In the first embodiment, a non-adhesive film having a thickness of 1 μm is used. However, similar effects can be obtained with a non-adhesive film having a thickness of 0.1 to 10 μm.

(Embodiment 2) FIG. 2 is a sectional view of a piston pin of a reciprocating compressor according to the present invention. The other configuration of the reciprocating compressor of the present invention is the same as that of the first embodiment, and the same reference numerals are given and the detailed description is omitted. In FIG. 2, reference numeral 23 denotes a piston pin, and reference numeral 24 denotes a non-adhesive film formed on the surface of the piston pin on the crankshaft 1 side.

The connecting rod 5 is an aluminum die-cast ADC 14, and the base material is made of a eutectic structure and primary crystal silicon. The sliding portion with the piston pin 23 is finished to a surface roughness Ra of 0.5 μm or less by honing.

The piston pin 23 is made of tool steel SKD1.
And a hardness HRC55 by quenching and tempering.
Has been adjusted. After polishing to a surface roughness Ra of 0.05 μm or less, a thickness of 1 μm
The non-adhesive film 24 made of TiALN is formed.

Here, the non-adhesive film 24 made of TiALN is a film used for preventing erosion of a die or the like of an aluminum die-casting. The superiority is described in "Metal Press, June 1997, pp. 12-16" and the like.

Next, the operation will be described. The motion of the crankshaft 1 eccentrically rotated by the drive source is transmitted to the piston 2 via the connecting rod 5 and the piston pin 23.
And the gas such as the refrigerant is compressed by the piston 2 reciprocating. At this time, the compressive load applied to the piston 2 is
3 and the crankshaft 1 act so as to press against each other.

At the connection between the connecting rod 5 and the crankshaft 1, the crankshaft 1 rotates and is mainly fluid-lubricated with lubricating oil (not shown). On the other hand, connecting rod 5 and piston pin 23
Since the connecting rod 5 oscillates with respect to the fixed piston pin 23, a fluid film is not easily formed by the lubricating oil, and metal contact occurs at a part of the sliding surface.

At this time, the aluminum forming the connecting rod 5 does not adhere to the non-adhesive film 24 formed on the surface of the piston pin 23, thereby avoiding the transition of aluminum to severe adhesive wear. As a result, the temperature rise around the connecting portion between the connecting rod 5 and the piston pin 23 is reduced, the separation of the lubricating oil from the sliding surface is suppressed, and the transition to the dry friction state is prevented.

As described above, in the second embodiment, the non-adhesive film prevents the aluminum forming the connecting rod from adhering to the surface of the piston pin, thereby avoiding the adhesive wear between the aluminum members. Thus, the temperature rise can be reduced, the separation of the lubricating oil from the sliding surface can be suppressed, and the transition to the dry friction state can be prevented. Also, by forming the non-adhesive film as thin as 1 μm around the crankshaft side surface of the piston pin to which a compressive load is applied, the dimension of the connecting portion between the connecting rod and the piston pin is increased due to the formation of the lubricating film. And achieve the intended purpose while suppressing changes in clearance.

In the second embodiment, a non-adhesive film having a thickness of 1 μm is used. However, similar effects can be obtained with a non-adhesive film having a thickness of 0.1 to 10 μm.

(Embodiment 3) FIG. 3 is a sectional view of a piston pin of a reciprocating compressor according to the present invention. The other configuration of the reciprocating compressor of the present invention is the same as that of the first embodiment, and the same reference numerals are given and the detailed description is omitted. In FIG. 3, reference numeral 33 denotes a piston pin, and reference numeral 34 denotes a non-adhesive film formed on the surface of the piston pin on the crankshaft 1 side.

The connecting rod 5 is an aluminum die-cast ADC 14, and the base material is made of a eutectic structure and primary crystal silicon. The sliding portion with the piston pin 33 is finished to a surface roughness Ra of 0.5 μm or less by honing.

The piston pin 33 is made of tool steel SKD1.
And a hardness HRC55 by quenching and tempering.
Has been adjusted. After polishing to a surface roughness Ra of 0.05 μm or less, a non-adhesive film 34 made of diamond-like carbon having a thickness of 1 μm is formed on the surface by ion plating.

Here, the non-adhesive film 34 made of diamond-like carbon is a film used for preventing adhesion to a tool for manufacturing an aluminum can or the like, and has a higher coefficient of friction with aluminum than a ceramic film. That
"Technical data of DLC coating of Nanotech Co., Ltd."
And so on. In addition, in the 1000-time start-up test for the ADC 14, the non-adhesive coating 34
Remained almost unchanged and maintained a static friction coefficient of about 0.2.

Next, the operation will be described. The motion of the crankshaft 1 eccentrically rotated by the drive source is transmitted to the piston 2 via the connecting rod 5 and the piston pin 33.
And the gas such as the refrigerant is compressed by the piston 2 reciprocating. At this time, the compressive load applied to the piston 2 is applied to the piston pin 3 with the connecting rod 5 interposed therebetween.
3 and the crankshaft 1 act so as to press against each other.

At the connection between the connecting rod 5 and the crankshaft 1, the crankshaft 1 rotates and is mainly fluid-lubricated with lubricating oil (not shown). On the other hand, connecting rod 5 and piston pin 33
Since the connecting rod 5 oscillates with respect to the fixed piston pin 33, a fluid film is not easily formed by lubricating oil, and metal contact occurs on a part of the sliding surface.

At this time, the aluminum forming the connecting rod 5 does not adhere to the non-adhesive film 34 formed on the surface of the piston pin 33, thereby avoiding the transition of aluminum to severe adhesive wear. In addition, the coefficient of static friction at the time of repetitive activation, which is generated during the rocking motion, is maintained at about 0.2. As a result, the temperature rise around the connecting portion between the connecting rod 5 and the piston pin 33 is reduced, the separation of the lubricating oil from the sliding surface is suppressed, and the transition to the dry friction state is prevented.

As described above, in the third embodiment, the non-adhesive film prevents the aluminum forming the connecting rod from adhering to the surface of the piston pin, thereby avoiding the adhesive wear of the aluminum and the static friction. By keeping the coefficient at about 0.2, the temperature rise can be reduced, the separation of the lubricating oil from the sliding surface can be suppressed, and the transition to the dry friction state can be prevented. In addition, a non-adhesive coating is applied to the piston pin, to which a compressive load is applied, with a 1μ
By forming as thin as m, the intended purpose can be achieved while suppressing an increase in the dimension of the connecting portion between the connecting rod and the piston pin and a change in clearance due to the formation of the lubricating film.

In the third embodiment, a non-adhesive film having a thickness of 1 μm is used. However, similar effects can be obtained with a non-adhesive film having a thickness of 0.1 to 10 μm.

(Embodiment 4) FIG. 4 is a sectional view of a piston pin of a reciprocating compressor according to the present invention. The other configuration of the reciprocating compressor of the present invention is the same as that of the first embodiment, and the same reference numerals are given and the detailed description is omitted. In FIG. 4, reference numeral 43 denotes a piston pin, and reference numeral 44 denotes a non-adhesive film formed on the surface of the piston pin on the crankshaft 1 side.

The connecting rod 5 is an aluminum die-cast ADC 14, and the base material is made of a eutectic structure and primary crystal silicon. The sliding part with the piston pin 43 is finished to a surface roughness Ra of 0.5 μm or less by honing.

The piston pin 43 is made of chromium molybdenum steel SCM415, and its surface hardness is adjusted to Hv800 by carburizing and tempering. Surface roughness Ra
After polishing to a thickness of 0.05 μm or less, a surface having a thickness of 1 μm was formed on the surface by a combination of sputtering and ion plating.
A non-adhesive film 44 composed of m and molybdenum disulfide and titanium is formed. The hardness of the non-adhesive coating 44 is H
v is about 500.

Here, the non-adhesive film 44 composed of a double phase of molybdenum disulfide and titanium is a MOST coating of Osaka Vacuum Industry Co., Ltd., and is used for preventing adhesion of aluminum material to cutting tools and the like. Further, it is described in “Catalog of Osaka Vacuum Industry Co., Ltd.” and the like that it is superior in durability to molybdenum disulfide single phase coating.
In addition, in the 1000-fold start-up test for the ADC 14, the non-adhesive coating 44 hardly changed and maintained a static friction coefficient of about 0.2 as compared with the static friction coefficient increasing several times without treatment. .

Next, the operation will be described. The motion of the crankshaft 1 eccentrically rotated by the drive source is transmitted to the piston 2 via the connecting rod 5 and the piston pin 43.
And the gas such as the refrigerant is compressed by the piston 2 reciprocating. At this time, the compressive load applied to the piston 2 is applied to the piston pin 3 with the connecting rod 5 interposed therebetween.
3 and the crankshaft 1 act so as to press against each other.

At the connection between the connecting rod 5 and the crankshaft 1, the crankshaft 1 rotates and is mainly fluid-lubricated with lubricating oil (not shown). On the other hand, connecting rod 5 and piston pin 43
Since the connecting rod 5 oscillates with respect to the fixed piston pin 43 at the connecting portion, a fluid film is not easily formed by the lubricating oil, and metal contact occurs on a part of the sliding surface.

At this time, the aluminum forming the connecting rod 5 does not adhere to the non-adhesive film 44 formed on the surface of the piston pin 43, thereby avoiding the transition of aluminum to severe adhesive wear. In addition, the coefficient of static friction at the time of repetitive activation, which is generated during the rocking motion, is maintained at about 0.2. As a result, the temperature rise around the connecting portion between the connecting rod 5 and the piston pin 43 is reduced, the separation of the lubricating oil from the sliding surface is suppressed, and the transition to the dry friction state is prevented.

As described above, in the fourth embodiment, the non-adhesive film prevents the aluminum forming the connecting rod from adhering to the surface of the piston pin, thereby avoiding the adhesive wear of the aluminum and the static friction. By keeping the coefficient at about 0.2, the temperature rise can be reduced, the separation of the lubricating oil from the sliding surface can be suppressed, and the transition to the dry friction state can be prevented. Further, the non-adhesive coating made of molybdenum disulfide has a low hardness of about Hv500, so that it is not necessary to increase the base metal hardness, and a relatively inexpensive material such as chromium molybdenum steel can be selected.

Further, by forming the non-adhesive film as thin as 1 μm around the crankshaft-side surface of the piston pin to which a compressive load is applied, the connection portion between the connecting rod and the piston pin accompanying the formation of the lubricating film is formed. The intended purpose is achieved while suppressing an increase in dimensions and a change in clearance.

In the fourth embodiment, a non-adhesive film having a thickness of 1 μm is used. However, similar effects can be obtained with a non-adhesive film having a thickness of 0.1 to 10 μm. Also,
In the fourth embodiment, a non-adhesive film composed of a double phase of molybdenum disulfide and titanium is used. This is to improve the adhesion and durability of the film, and to exhibit non-adhesiveness. In this case, a single phase of molybdenum disulfide or a multiple phase with another metal may be used.

(Embodiment 5) FIG. 5 is a sectional view of a piston pin of a reciprocating compressor according to the present invention. The other configuration of the reciprocating compressor of the present invention is the same as that of the first embodiment, and the same reference numerals are given and the detailed description is omitted. 5, reference numeral 1 denotes a crankshaft connected to a drive source (not shown), 2 denotes a piston reciprocating in a cylinder (not shown), 53 denotes a steel piston pin fixed to the piston 2, and 54 denotes a piston pin. Thickness 1 formed on the surface of piston pin 53
The non-adhesive coating 5 μm is a connecting rod made of an aluminum alloy connecting the crankshaft 1 and the piston pin 53.

Here, the lubricating oil (not shown) is obtained by adding one part of an alcoholic oiliness improver having a molecular weight of 130 to paraffinic mineral oil.
%. Extreme pressure agents, carboxylic acid oil improvers, and ester oil improvers violently react with iron and aluminum at high temperatures to cause corrosion and abrasion. It is difficult to select an additive having properties. On the other hand, alcohol-based oiliness improvers are effective only in the range where the lubricating state is relatively good, but have low reactivity with iron and aluminum,
Low risk of corrosion and wear. For example, “Japanese Tribology Conference Tribology Conference Proceedings 1993-11, P5
65-566 "and the like.

Next, the operation will be described. The motion of the crankshaft 1 eccentrically rotated by the drive source is transmitted to the piston 2 via the connecting rod 5 and the piston pin 53.
And the gas such as the refrigerant is compressed by the piston 2 reciprocating. At this time, the compression load applied to the piston 2 is
3 and the crankshaft 1 act so as to press against each other.

At the connection between the connecting rod 5 and the crankshaft 1, the crankshaft 1 rotates and is mainly fluid-lubricated with lubricating oil. On the other hand, at the connecting portion between the connecting rod 5 and the piston pin 53,
Since the connecting rod 5 swings with respect to the fixed piston pin 53, a fluid film is not easily formed by the lubricating oil, and metal contact occurs on a part of the sliding surface.

At this time, the non-adhesive film 54 formed on the surface of the piston pin 53 and the metal contact portion of the connecting portion of the connecting rod 5 slide, so that the aluminum forming the connecting rod 5 is melted. Even under such severe conditions, the adhesion of aluminum to the surface of the piston pin 53 is prevented. As a result, the temperature rise around the connecting portion between the connecting rod 5 and the piston pin 53 is reduced, the separation of the lubricating oil from the sliding surface is suppressed, and the transition to the dry friction state is prevented.

When the base material of the piston pin 53, which has been smoothed by the non-adhesive film 54 being worn out by the initial conformal wear, is exposed, the alcohol-based oiliness improver compounded with the lubricating oil is applied to the surface of the piston pin 53. To prevent the aluminum forming the connecting rod 5 from adhering.

As described above, in the fifth embodiment, the non-adhesive film or the alcohol-based oiliness improver is used to prevent the aluminum forming the connecting rod from adhering to the piston pin surface, so that the two The purpose of the present invention is to reduce the temperature rise by avoiding cohesive wear, suppress the separation of the lubricating oil from the sliding surface, and prevent the transition to the dry friction state. Also, by using an alcohol-based oiliness improver in combination, even if the non-adhesive film is worn out due to initial abrasion, the adhesion is suppressed by the smoothed surface state and the synergistic effect of the alcohol-based oiliness improver. The purpose of this is to achieve.

In the fifth embodiment, 1% of an alcoholic oiliness improver having a molecular weight of 130 is blended. However, the main chain having an alcohol group adsorbed on steel forming the piston pin and exhibiting lubricity is made of carbon. A similar effect can be obtained with 0.1 to 20% of an alcoholic oiliness improver of several tens or more.

(Embodiment 6) FIG. 6 is a sectional view of a piston pin of a reciprocating compressor of the present invention. The other configuration of the reciprocating compressor of the present invention is the same as that of the first embodiment, and the same reference numerals are given and the detailed description is omitted. 6, reference numeral 1 denotes a crankshaft connected to a driving source (not shown), 2 denotes a piston that reciprocates in a cylinder (not shown), 63 denotes a steel piston pin fixed to the piston 2, and 64 denotes a piston pin. Thickness 1 formed on the surface of piston pin 63
The non-adhesive film 5 μm is a connecting rod made of an aluminum alloy for connecting the crankshaft 1 and the piston pin 63.

The lubricating oil (not shown) is obtained by mixing 1% of a carbonate-based oiliness improver having a molecular weight of 314 with paraffin-based mineral oil. Extreme pressure agents, carboxylic acid oil improvers, and ester oil improvers violently react with iron and aluminum at high temperatures to cause corrosion and abrasion. It is difficult to select an additive having properties. On the other hand, the carbonate-based oiliness improver has a carbonate group having a polarity higher than that of the ester bond, and is more excellent in the adsorptivity to iron than the alcohol-based oiliness improver and the ester-based oiliness improver, and decomposed at high temperatures. It has the advantage that it does not corrode iron or aluminum as carbon dioxide and alcohol. For example, "International Symposium 'R22, R502 Alternative Refrigerant' 9
4 Proceedings, p. 119-123, etc., describe the reactivity of carbonate compounds.

Next, the operation will be described. The motion of the crankshaft 1 eccentrically rotated by the drive source is transmitted to the piston 2 via the connecting rod 5 and the piston pin 63.
And the gas such as the refrigerant is compressed by the piston 2 reciprocating. At this time, the compressive load applied to the piston 2 is sandwiched between the connecting rod 5 and the piston pin 6.
3 and the crankshaft 1 act so as to press against each other.

At the connection between the connecting rod 5 and the crankshaft 1, the crankshaft 1 rotates and is mainly fluid-lubricated with lubricating oil. On the other hand, at the connecting portion between the connecting rod 5 and the piston pin 63,
Since the connecting rod 5 swings with respect to the fixed piston pin 63, a fluid film is not easily formed by the lubricating oil, and metal contact occurs on a part of the sliding surface.

At this time, the non-adhesive coating 64 formed on the surface of the piston pin 63 and the metal contact portion of the connecting portion of the connecting rod 5 slide, so that the aluminum forming the connecting rod 5 is melted. Even under such severe conditions, it is possible to prevent aluminum from adhering to the surface of the piston pin 63. As a result, the temperature rise around the connecting portion between the connecting rod 5 and the piston pin 63 is reduced, the separation of the lubricating oil from the sliding surface is suppressed, and the transition to the dry friction state is prevented.

Then, when the non-adhesive film 64 is worn out by the initial break-in wear and the base material of the smoothed piston pin 63 is exposed, the carbonate-based oiliness improver blended with the lubricating oil is exposed to the surface of the piston pin 63. To prevent the aluminum forming the connecting rod 5 from adhering.

As described above, in the sixth embodiment, the non-adhesive coating or the carbonate-based oiliness improver is used to prevent the aluminum forming the connecting rod from adhering to the surface of the piston pin, thereby preventing the aluminum from forming. The purpose of the present invention is to reduce the temperature rise by avoiding cohesive wear, suppress the separation of the lubricating oil from the sliding surface, and prevent the transition to the dry friction state. Also, by using a carbonate-based oiliness improver in combination, even if the non-adhesive film is worn out due to initial abrasion, the adhesion is suppressed by the smoothed surface state and the synergistic effect of the carbonate-based oiliness improver. The purpose of this is to achieve. In addition, carbonate-based oiliness improver,
Even if the temperature of the sliding portion becomes high temporarily, the high suction property is maintained, and the intended purpose is achieved without causing corrosion and wear.

In the sixth embodiment, 1% of a carbonate-based oiliness improver having a molecular weight of 314 is blended. However, both ends of the main chain having a carbonate group adsorbed on steel forming the piston pin and exhibiting lubricity are provided. A similar effect can be obtained with 0.1 to 20% of a carbonate-based oiliness improver having a total carbon number of 10 or more.

[0073]

As described above, according to the present invention, the surface of the piston pin of the reciprocating compressor on the crankshaft side is
By forming a non-adhesive coating, aluminum that forms the connecting rod on the piston pin surface is prevented from adhering, thereby avoiding cohesive abrasion between aluminum and reducing the temperature rise. Can be prevented from separating from the sliding surface and the transition to the dry friction state can be prevented.

Also, by forming the lubricating coating thin only on the crankshaft side surface of the piston pin to which a compressive load is applied, the size of the connecting portion between the connecting rod and the piston pin is increased and the clearance is increased due to the formation of the lubricating coating. To achieve the intended purpose while suppressing changes in

[Brief description of the drawings]

FIG. 1 is a sectional view of a reciprocating compressor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a piston pin of a reciprocating compressor according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a piston pin of a reciprocating compressor according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a piston pin of a reciprocating compressor according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a reciprocating compressor according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view of a reciprocating compressor according to a sixth embodiment of the present invention.

FIG. 7 is a sectional view of a conventional reciprocating compressor.

[Explanation of symbols]

 5 Connecting rod 13 Piston pin 14 Non-adhesive coating

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Nozue 4-5-2, Takaidahondori, Higashiosaka-shi, Osaka Matsushita Refrigerator Co., Ltd. F-term (reference) 3H076 AA02 BB17 BB26 CC24 CC31 CC34 CC61 CC99

Claims (6)

[Claims] 1. A reciprocating compressor in which a piston reciprocates in a cylinder while reciprocating, a crankshaft connected to a drive source, a steel piston pin fixed to the piston, and the crankshaft of the piston pin. A non-adhesive film having a thickness of 0.1 to 10 μm formed on the side surface, a connecting rod made of an aluminum alloy connecting the crankshaft and the piston pin, and a lubricating oil for lubricating each sliding portion. Reciprocating compressor. 2. The reciprocating compressor according to claim 1, wherein a TiALN ceramic film is formed on the surface of the piston pin as the non-adhesive film. 3. The reciprocating compressor according to claim 1, wherein a diamond-like carbon film is formed on the surface of the piston pin as the non-adhesive film. 4. The reciprocating compressor according to claim 1, wherein a molybdenum disulfide film is formed on the surface of the piston pin as the non-adhesive film. 5. The reciprocating compressor according to claim 1, wherein a lubricating oil containing an alcoholic oiliness improver is used. 6. The reciprocating compressor according to claim 1, wherein a lubricating oil containing a carbonate-based oiliness improver is used.