JP7405382B2 - Compressor and refrigeration cycle equipment - Google Patents

Description

Embodiments of the present invention relate to a compressor that sucks in and discharges working fluid, and a refrigeration cycle device.
This application claims priority based on Japanese Patent Application No. 2020-078679 filed in Japan on April 27, 2020, the contents of which are incorporated herein.

For example, in a refrigeration cycle device such as an air conditioner, a compressor such as a refrigerant compressor is used that has a compression mechanism section that sucks in and discharges a refrigerant as a working fluid (for example, Patent Document 1). In order to increase the efficiency of a compressor, it is important to reduce friction loss between sliding surfaces that slide against each other. However, in a conventional compressor such as that disclosed in Patent Document 1, it is difficult to efficiently and stably reduce the friction loss of sliding surfaces that slide on each other over a long period of time.

Japanese Patent Application Publication No. 2004-316522

The problem to be solved by the present invention is to provide a compressor that can efficiently and stably reduce friction loss between sliding surfaces that slide on each other over a long period of time, and a refrigeration cycle device using the compressor. .

The compressor of the embodiment has a compression mechanism section that sucks and discharges working fluid, and of a first sliding surface and a second sliding surface of the compression mechanism section that slide against each other, the first sliding surface A polymer brush is provided on a second sliding surface having a smaller area than the surface.

1 is a schematic configuration diagram showing an example of a refrigeration cycle device according to an embodiment. FIG. 2 is a cross-sectional view taken along line AA of the compression mechanism in the refrigeration cycle device shown in FIG. 1; The perspective view which showed the vane of the compression mechanism part of embodiment. FIG. 3 is an enlarged cross-sectional view showing the sliding contact portion between the tip end surface of the vane and the inner circumferential surface of the cylinder in FIG. 2; FIG. 3 is a cross-sectional view showing the state of wear on a sliding surface provided with polymer brushes. FIG. 1 is a schematic diagram of a reciprocating compressor according to an embodiment. FIG. 7 is an enlarged cross-sectional view showing the sliding contact portion between the upper part of the outer circumferential surface of the piston and the inner circumferential surface of the cylinder in FIG. 6; 1 is a schematic diagram showing a block-on-ring tester used in Examples. FIG. 4 is a diagram showing the depth of wear on the sliding surfaces of blocks in Experimental Examples 1 to 4. Two-layer separation temperature diagram in Experimental Example 5.

The following definitions of terms apply throughout the specification and claims.
The term "sliding surface" refers to a surface on which a plurality of components constituting the compression mechanism slide on each other, and is in sliding contact with each other via a lubricating oil film at the initial stage of sliding. Sliding surfaces also include surfaces on which polymer brushes slide.
"Non-sliding surface around the sliding surface" refers to the surface around the sliding surface of the component that is not in sliding contact with the sliding surface that the sliding surface is in sliding contact with at the initial stage of sliding. be. The non-sliding surface may be a surface that can become a sliding surface when wear of the sliding surface progresses over time, or it may be a surface that does not become a sliding surface.
"~" indicating a numerical range means that the numerical values written before and after it are included as lower and upper limits.

The compressor of the embodiment has a compression mechanism section that sucks in and discharges working fluid. The compression mechanism has a first sliding surface and a second sliding surface that is smaller in area than the first sliding surface that slide against each other, and a polymer brush is provided on the second sliding surface. It is provided. The compressor only needs to have a compression mechanism section that sucks in and discharges working fluid, and any known configuration can be adopted without limitation, except that a polymer brush is provided on the second sliding surface of the compression mechanism section.
Further, the refrigeration cycle device of the embodiment includes a compressor, a radiator, an expansion device, and an evaporator, and a known aspect can be adopted except for including the compressor having the above characteristics.

Hereinafter, an example of a compressor and a refrigeration cycle device according to an embodiment will be described.
As shown in FIG. 1, the refrigeration cycle device 1 of this embodiment includes a compressor 2, a condenser 3 which is a radiator connected to the compressor 2, and an expansion device 4 connected to the condenser 3. An evaporator 5 as a heat absorber is connected between the expansion device 4 and the compressor 2.

The compressor 2 is a so-called rotary vane type compressor, which takes in a low-pressure gas refrigerant (working fluid) as a working fluid and compresses it into a high-temperature, high-pressure gas refrigerant. Note that the compressor is not limited to a rotary type, and may be a scroll type, a reciprocating type, a swash plate type, or the like. The specific configuration of the compressor 2 will be described later.
The condenser 3 radiates heat from the high-temperature, high-pressure gaseous refrigerant sent from the compressor 2 to convert it into a high-pressure liquid refrigerant (working fluid).

The expansion device 4 lowers the pressure of the high-pressure liquid refrigerant sent from the condenser 3 to turn it into a low-temperature, low-pressure liquid refrigerant.
The evaporator 5 vaporizes the low-temperature, low-pressure liquid refrigerant sent from the expansion device 4, and converts the low-temperature, low-pressure liquid refrigerant into a low-pressure gas refrigerant. In the evaporator 5, when the low-pressure liquid refrigerant is vaporized, heat of vaporization is removed from the surroundings, thereby cooling the surroundings. Note that the low-pressure gas refrigerant that has passed through the evaporator 5 is taken into the compressor 2.
In this way, in the refrigeration cycle device 1 of this embodiment, the refrigerant, which is the working fluid, circulates while changing its phase into a gas refrigerant and a liquid refrigerant.

The compressor 2 includes a compressor main body 11 and an accumulator 12.
The accumulator 12 is a so-called gas-liquid separator. The accumulator 12 is provided between the evaporator 5 and the compressor main body 11. The accumulator 12 is connected to the compressor body 11 through a suction pipe 21. The accumulator 12 supplies only the gas refrigerant to the compressor body 11 out of the gas refrigerant vaporized in the evaporator 5 and the liquid refrigerant not vaporized in the evaporator 5 .

The compressor main body 11 includes a drive shaft 31, a drive element 32, a compression mechanism section 33, and an airtight container 34 that houses the drive shaft 31, drive element 32, and compression mechanism section 33.
The closed container 34 is formed into a cylindrical shape, and both ends in the axial direction are closed. A lubricant J is contained in the closed container 34. A portion of the compression mechanism section 33 is immersed in the lubricant J.

The drive shaft 31 is coaxially arranged along the axis O1 of the closed container 34. In the following description, the direction along the axis O1 is simply referred to as the axial direction, the direction perpendicular to the axial direction is referred to as the radial direction, and the direction around the axis O1 is referred to as the circumferential direction.

The drive element 32 is arranged on the first axial side within the closed container 34 . The compression mechanism section 33 is arranged on the second side in the axial direction within the closed container 34 . In the following description, the drive element 32 side (first side) along the axial direction will be referred to as the upper side, and the compression mechanism section 33 side (second side) will be referred to as the lower side.

The drive element 32 is a so-called inner rotor type DC brushless motor. Specifically, the drive element 32 includes a stator 35 and a rotor 36.
The stator 35 is fixed to the inner wall surface of the closed container 34 by shrink fitting or the like.
The rotor 36 is fixed to the upper part of the drive shaft 31 inside the stator 35 with an interval in the radial direction.

The compression mechanism section 33 includes a cylindrical cylinder 41 through which the drive shaft 31 passes, a main bearing 42 and a sub-bearing that separately close openings at both ends of the cylinder 41 in the axial direction, and rotatably support the drive shaft 31. It is equipped with 43 and.

As shown in FIG. 1, the main bearing 42 includes a cylindrical portion 42a into which the drive shaft 31 is inserted, and a flange portion 42b that protrudes radially outward from the lower end of the cylindrical portion 42a. There is. The main bearing 42 closes the upper end opening of the cylinder 41. Further, the main bearing 42 rotatably supports a portion of the drive shaft 31 located above the cylinder 41.

The sub-bearing 43 includes a cylindrical portion 43a into which the drive shaft 31 is inserted, and a flange portion 43b protruding radially outward from the upper end of the cylindrical portion 43a. The sub-bearing 43 closes the lower end opening of the cylinder 41. Further, the sub bearing 43 rotatably supports a portion of the drive shaft 31 located below the cylinder 41.

A space formed by the cylinder 41, the main bearing 42, and the sub-bearing 43 constitutes a working chamber 45 (see FIG. 2).
As shown in FIG. 2, a piston 46 is fitted onto a portion of the drive shaft 31 inside the cylinder 41. As shown in FIG. The piston 46 rotates within the cylinder 41 as the drive shaft 31 rotates, and the outer circumferential surface 46a of the piston 46 slides on the inner circumferential surface 41a of the cylinder 41 via a lubricating oil film.

Two vane slots 47 are formed in the piston 46, which extend from a position close to the drive shaft 31 to an outer circumferential surface 46a of the piston 46 in plan view. The vane slot 47 is formed throughout the cylinder 41 in the axial direction (height direction).

A vane 48 shown in FIG. 3 is provided within the vane slot 47. In plan view from the axial direction, the tip end surface 48a of the vane 48 has an arcuate shape that is convex toward the outside in the radial direction. Further, each vane 48 is biased toward the inner circumferential surface 41a of the cylinder 41. Therefore, as shown in FIG. 2, in each vane slot 47, as the piston 46 rotates, the vane 48 slides back and forth when viewed from the outer peripheral surface 46a side of the piston 46, and the tip surface 48a of the vane 48 At least a portion thereof remains in contact with the inner circumferential surface 41a of the cylinder 41. Lubricating oil J is interposed between the tip surface 48a of the vane 48 and the inner peripheral surface 41a of the cylinder 41. Thereby, the vane 48 rotates as the piston 46 rotates, and the tip surface 48a of the vane 48 slides on the inner peripheral surface 41a of the cylinder 41. The working chamber 45 of the cylinder 41 is divided by a piston 46 and two vanes 48 into a suction chamber 45a and a compression chamber 45b.

The cylinder 41 includes a suction passage 49 that radially penetrates the cylinder 41 and opens into the suction chamber 45a of the working chamber 45, and a discharge port that radially passes through the cylinder 41 and opens into the compression chamber 45b of the working chamber 45. 50 are formed. A discharge valve 51 is disposed outside the discharge port 50 of the cylinder 41 to open and close the discharge port 50 as the pressure in the working chamber 45 (compression chamber 45b) increases and to discharge gaseous refrigerant to the outside of the working chamber 45. ing. As shown in FIG. 1, the main bearing 42 is provided with a discharge muffler 52 that covers the main bearing 42 from above. The discharge muffler 52 is formed with a communication hole 53 that communicates the inside and outside of the discharge muffler 52 .

In the compressor 2, when power is supplied to the stator 35 of the drive element 32, the drive shaft 31 rotates together with the rotor 36 around the axis O1. As the drive shaft 31 rotates, the piston 46 rotates within the working chamber 45. At this time, the outer circumferential surface 46a of the piston 46 comes into sliding contact with a portion of the inner circumferential surface 41a of the cylinder 41 between the suction passage 49 and the discharge port 50 via a lubricating oil film. Also, when viewed from the outer circumferential surface 46a side of the piston 46, the vane 48 in the vane slot 47 slides back and forth, and at least a portion of the tip surface 48a of the vane 48 contacts the inner circumferential surface 41a of the cylinder 41 via a lubricating oil film. Always make sliding contact. As the piston 46 rotates, gaseous refrigerant (working fluid) is taken into the working chamber 45 from the suction passage 49, and the gaseous refrigerant taken into the working chamber 45 is compressed.

Specifically, the gaseous refrigerant is sucked into the suction chamber 45a of the working chamber 45 from the suction passage 49, and the gaseous refrigerant previously sucked from the suction passage 49 is compressed in the compression chamber 45b. The compressed high-temperature, high-pressure gas refrigerant is discharged to the outside of the working chamber 45 (inside the discharge muffler 52 ) through the discharge port 50 and discharged into the closed container 34 through the communication hole 53 . The gas refrigerant discharged into the closed container 34 is sent to the condenser 3.

The material of each member in the compression mechanism section 33 is not particularly limited. The material of the cylinder 41, main bearing 42, and sub-bearing 43 is, for example, gray cast iron such as FC250, and the material of the piston 46 is, for example, special alloy cast iron (monichrome cast iron) made by adding Mo, Ni, Cr, etc. to FC250 gray cast iron. ). The vane 48 may be made of, for example, SUS440C subjected to gas nitriding treatment.

In the compression mechanism section 33 of the compressor 2, the tip surface 48a of the vane 48 and the inner peripheral surface 41a of the cylinder 41 are sliding against each other. The area of the tip surface 48a of the vane 48 is smaller than the area of the inner circumferential surface 41a of the cylinder 41, the inner circumferential surface 41a of the cylinder 41 is the first sliding surface, and the tip surface 48a of the vane 48 is the second sliding surface. Including moving surfaces.

More specifically, as shown in FIG. 4, when viewed in plan from the axial direction, the inner circumferential surface 41a of the cylinder 41 has a concave arc shape toward the outside in the radial direction, and the tip surface of the vane 48 48a has a circular arc shape that is convex toward the outside in the radial direction. At the initial stage of sliding, a portion of the tip end surface 48a of the vane 48 is in linear sliding contact with the inner circumferential surface 41a of the cylinder 41 in the axial direction via a lubricating oil film in plan view. Further, the high pressure side (compression chamber 45b side) and the low pressure side (suction chamber 45a side) of the sliding contact portion of the tip surface 48a of the vane 48 have an arcuate shape that moves away from the inner circumferential surface 41a of the cylinder 41, respectively.

In this way, the tip surface 48a of the vane 48 has a second sliding surface 48b that slides in sliding contact with the inner circumferential surface 41a of the cylinder 41 via a lubricating oil film at the initial stage of sliding, and a high-pressure side of the second sliding surface 48b. and a non-sliding surface 48c that exists on the low pressure side. A non-sliding surface 48c around the second sliding surface 48b on the tip surface 48a of the vane 48 is not in sliding contact with the inner circumferential surface 41a of the cylinder 41 at the initial stage of sliding. As time passes and the wear of the second sliding surface 48b progresses due to sliding, the non-sliding surface 48c comes into sliding contact with the inner circumferential surface 41a of the cylinder 41 via a lubricating oil film, and becomes a second sliding surface. It can be.

In the compression mechanism section 33, a polymer brush 80 is provided on the tip surface 48a of the vane 48, which has a smaller area than the inner circumferential surface 41a of the cylinder 41. The polymer brush 80 is formed from a plurality of polymer chains, exhibits excellent mechanical properties such as high compression resistance and low frictional resistance, and can retain the lubricant J. Thereby, wear of the tip surface 48a of the vane 48 is sufficiently suppressed by the lubricant J. Details of the polymer brush will be described later.

In addition, when sliding surfaces with different areas slide, the sliding surface with a smaller area spends more time in sliding contact with the other sliding surface than the sliding surface with a larger area, and the friction conditions are harsher and wears out. High risk. In the compression mechanism section 33, by providing the polymer brush 80 on the tip surface 48a of the vane 48, which has a smaller area, a small amount of the polymer brush 80 can economically and effectively reduce the wear of the second sliding surface 48b, which has a high risk of wear. can be suppressed. Furthermore, friction loss can be efficiently and stably reduced over a long period of time. In particular, in a vane type compressor such as the compressor 2, the tip surface 48a of the vane 48 has the highest risk of wear, so by providing the polymer brush 80 on the tip surface 48a of the vane 48, it is possible to more effectively improve reliability. It can be a high compressor 2.

As described above, the tip surface 48a of the vane 48 has a convex arc shape in plan view, and the high pressure side and the low pressure side are far from the inner circumferential surface 41a of the cylinder 41. Therefore, among the second sliding surfaces 48b, There are portions having different distances from the inner circumferential surface 41a of the cylinder 41, which is the first sliding surface. In this way, if there are parts of the second sliding surface that are different in distance from the first sliding surface, then there are parts of the polymer brush where the distance between the second sliding surface and the first sliding surface is large. It is preferable that the occupied area ratio of the polymer is higher than the occupied area ratio of the polymer in the part where the distance is small. As a result, in areas where the distance between the first sliding surface and the second sliding surface is small, the polymer brushes are sparse, reducing friction in the fluid lubrication area where sliding through the lubricant film is the main effect. Improves effectiveness. On the other hand, in areas where the distance between the first sliding surface and the second sliding surface is large, the polymer brushes are dense, so the effect of dispersing the sliding load through the polymer brushes is high, resulting in wear and tear on the sliding surface. can be efficiently suppressed. These factors further enhance the effect of efficiently and stably reducing friction loss over a long period of time.

In the tip surface 48a of the vane 48 of this embodiment, a polymer brush 80 is provided over the entire tip surface 48a. That is, on the tip surface 48a of the vane 48, the polymer brush 80 is provided not only on the second sliding surface 48b but also on the non-sliding surface 48c around the second sliding surface 48b. In this way, by providing the polymer brush to the non-sliding surface around the second sliding surface, even if the second sliding surface is worn together with the polymer brush and the sliding surface is enlarged, The progress of wear is further suppressed by polymer brushes provided on the surrounding non-sliding surfaces. Therefore, high reliability can be maintained for a longer period of time.
Note that a configuration may also be adopted in which the polymer brush is not provided on the non-sliding surface around the second sliding surface.

In the compression mechanism section 33, the working chamber 45 is divided into a high pressure compression chamber 45b and a low pressure suction chamber 45a with the tip surface 48a of the vane 48 in sliding contact with the inner peripheral surface 41a of the cylinder 41. In this way, the inner circumferential surface 41a (first sliding surface) of the cylinder 41 and the second sliding surface 48b on the tip surface 48a of the vane 48 divide the gas refrigerant (working fluid) with a pressure difference. It is also a sealing surface.

In this way, when the first sliding surface and the second sliding surface are sealing surfaces that divide and seal the working fluid with a pressure difference, at least the non-sliding surface on the high pressure side of the second sliding surface Preferably, the moving surface is provided with polymer brushes. As a specific example, when the polymer brush 80 is provided on the non-sliding surface 48c of the tip surface 48a of the vane 48, the polymer brush 80 is provided on the non-sliding surface 48c at least on the high pressure side (compression chamber 45b side) of the second sliding surface 48b. Preferably, a brush 80 is provided. As a result, even if the supply of lubricant J is temporarily interrupted, the lubricant J held in the polymer brush 80 on the high-pressure side non-sliding surface 48c is supplied to the second sliding surface 48b due to the differential pressure. Therefore, the compressor 2 becomes even more reliable and can cope with lubricant shortages.

In the compression mechanism section 33, the radius of curvature of the inner peripheral surface 41a of the cylinder 41 and the radius of curvature of the tip surface 48a of the vane 48 (the radius of curvature of the second sliding surface 48b) are different. In this way, when the radii of curvature of the first sliding surface and the second sliding surface are different from each other, the contact pressure between the first sliding surface and the second sliding surface is expressed by the following formula (1). It is preferable that sliding contact be made in a linear manner so as to satisfy the expressed conditions.

However, in formula (1), F is the load (N) that the first sliding surface and the second sliding surface receive. L is the length (mm) of the linear sliding contact portion between the first sliding surface and the second sliding surface. A is represented by the following formula (2).

However, in formula (2), E1 is the longitudinal elastic modulus (MPa) of the base material forming the first sliding surface. E2 is the longitudinal elastic modulus (MPa) of the base material forming the second sliding surface. ν1 is the Poisson's ratio of the base material forming the first sliding surface. ν2 is the Poisson's ratio of the base material forming the second sliding surface. R1 is the radius of curvature (mm) of the first sliding surface when viewed from the length direction of the linear sliding portion. R2 is the radius of curvature (mm) of the second sliding surface when viewed from the length direction of the linear sliding portion. The radius of curvature is a positive value when the sliding surface is a convex surface, a negative value when the sliding surface is a concave surface, and an infinite value when the sliding surface is a flat surface.

Generally, when a lubricant is compatible with a working fluid, the kinematic viscosity of the lubricant decreases, making it easier for sliding surfaces to wear out. However, in the formula expressing Hertz's contact surface pressure shown in Mechanical Engineering Handbook A4-109, if the contact pressure between the first sliding surface and the second sliding surface satisfies the condition of equation (1), lubrication Even when the agent is compatible with the working fluid, a sufficient effect of suppressing wear on the sliding surface can be easily obtained.

The surface hardness of the tip surface 48a of the vane 48 including the second sliding surface 48b is preferably higher than the surface hardness of the inner circumferential surface 41a of the cylinder 41, which is the first sliding surface. The surfaces of the sliding surfaces that slide against each other are gradually scraped by the friction caused by sliding. Since the surface hardness of the second sliding surface is higher than that of the first sliding surface, the amount of wear on the second sliding surface due to initial wear and the like is reduced. As a result, more polymer brushes can remain on the second sliding surface for a long period of time, which further increases the effect of reducing wear on the sliding surface and further increases the effect of reducing friction loss.

To explain more specifically, there are usually fine irregularities on the surface of the base material of each component of the compression mechanism section. When the polymer brush 80 is provided on the sliding surface 74 with a low surface hardness or the sliding surface 76 with a high surface hardness, in the non-sliding state, as shown in FIG. Polymers are bonded evenly.

However, the sliding surface 74 with low surface hardness is easily worn. Therefore, when the compressor operates and the sliding surface 74 slides, the sliding interface Y of the sliding surface 74 approaches the bottom of the recess in a short time due to wear, as shown in FIG. 5(C). , a worn surface 70 where the protrusions are shaved off and the polymer is peeled off is formed over a wide area.
On the other hand, when the polymer brush 80 is provided on the sliding surface 76, which has a high surface hardness, the sliding surface 76 is less likely to wear than the sliding surface 74, so as shown in FIG. The sliding boundary surface X of the surface 76 is difficult to move in the depth direction. As a result, the worn surface 70 where the protrusions are scraped and the polymer peeled off is difficult to spread, and much of the polymer of the polymer brush 80 remains on the sliding surface 76 for a long time. Therefore, the effect of reducing friction loss by the polymer brush becomes even higher.

The difference between the surface hardness of the second sliding surface and the first sliding surface is preferably 50 HV to 2830 HV, more preferably 200 HV to 2000 HV. If the difference in surface hardness is greater than or equal to the lower limit of the range, wear of the second sliding surface is reduced relative to the first sliding surface. If the difference in surface hardness is below the upper limit of the range, significant wear of the first sliding surface due to the difference in hardness is prevented.

The surface hardness of the first sliding surface is preferably 170HV to 600HV, more preferably 200HV to 520HV.
The surface hardness of the second sliding surface is preferably 220HV to 3000HV, more preferably 500HV to 2500HV.

The second sliding surface may be an untreated surface of the base material, or may be a surface whose surface hardness is increased by subjecting the surface of the base material to a surface hardening treatment. The method of increasing the surface hardness through surface hardening treatment allows for the use of base materials with low hardness as the base material for forming the second sliding surface of the vane 48, etc., which increases the choice of material for the base material. It is advantageous in that flexibility in terms of spread, manufacturability, productivity, availability, etc. is improved.

The surface hardening treatment is not particularly limited as long as it can increase the surface hardness, and examples thereof include diamond-like carbon (DLC) coating, gas nitriding treatment, carburizing treatment, and the like.

For example, by using gray cast iron equivalent to FC250 as the material of the cylinder 41, the surface hardness of the inner peripheral surface 41a of the cylinder 41 can be set to HRB93 (Vickers hardness: equivalent to 210 HV) in terms of Rockwell hardness. By using SKH51 as the material of the vane 48, the surface hardness of the tip surface 48a of the vane 48 can be set to HRC63 (Vickers hardness: equivalent to 770HV) in terms of Rockwell hardness, and a DLC coating is further applied as a surface hardening treatment. By doing so, the surface hardness can be set to 2500 HV in terms of Vickers hardness.

The surface roughness Ra of the tip surface 48a of the vane 48, which is the second sliding surface, is preferably larger than the surface roughness Ra of the inner circumferential surface 41a of the cylinder 41, which is the first sliding surface. Since the surface roughness Ra of the second sliding surface is larger than the surface roughness Ra of the first sliding surface, even if wear progresses, more of the polymer brushes can reach the recesses of the second sliding surface. becomes more likely to remain. This makes it easier for the recessed portion of the second sliding surface to function as an oil spot (lubricating oil reservoir) over a long period of time, thereby increasing the effect of reducing wear on the sliding surface.

The surface roughness Ra of the second sliding surface is preferably 0.10 μm or more, more preferably 0.10 to 0.25 μm, and even more preferably 0.10 to 0.20 μm. If the surface roughness Ra of the second sliding surface is equal to or greater than the lower limit of the range, the effect of reducing wear on the sliding surface will be higher, and the reliability of the compressor will be higher.
Note that the surface roughness Ra of the sliding surface is the surface roughness Ra in a state without the polymer brush. Surface roughness Ra is measured in accordance with JIS B0601:2001.

The composite roughness α of the first sliding surface and the second sliding surface expressed by the following formula (3) is preferably 1.0 μm or less.
α={(α ₁ ) ² + (α ₂ ) ² } ^1/2 ...(3)
However, α ₁ in equation (3) is the surface roughness Ra of the first sliding surface. α ₂ is the surface roughness Ra of the second sliding surface.

The composite roughness α represents the standard deviation of the surface roughness Ra. By considering variations in surface roughness, the effectiveness of polymer brushes can be enhanced. If the composite roughness α is 1.0 μm or less, the effect of reducing wear on the sliding surface will be higher without making the polymer brush excessively long, and the reliability of the compressor will be higher.
For example, when the length of the polymer brush is about 2 μm, the composite roughness α is preferably 0.82 μm or less, more preferably 0.60 μm or less.

The working fluid is not particularly limited, and examples thereof include chlorine-free hydrocarbon refrigerants, carbon dioxide, saturated fluorinated hydrocarbon refrigerants, unsaturated fluorinated hydrocarbon refrigerants, fluorine-containing ether refrigerants, and the like. . As the working fluid, one type may be used alone, or two or more types may be used in combination.

The lubricant is not particularly limited, and examples thereof include lubricating oils such as mineral oil, polyol ester oil, polyvinyl ether oil, polyalkylene glycol oil, and polyalphaolefin oil. Note that the lubricant is not limited to lubricating oil, and may be a known ionic liquid or the like. As the lubricant, one type may be used alone, or two or more types may be used in combination.

In the compression mechanism section, it is preferable that the polymer brush provided on the second sliding surface be swollen with a lubricant that lubricates the compression mechanism section, and that the lubricant is compatible with the working fluid. When the polymer brush is swollen, its toughness against sliding loads is improved, and the sliding surface pressure is easily dispersed. In an embodiment in which the polymer brush is swollen by a lubricant that lubricates the compression mechanism, the lubricant is stably supplied to the polymer brush, and the swollen state of the polymer brush is easily maintained. In addition, since the lubricant is compatible with the working fluid, for example, when the compressor is used in a refrigeration cycle device, the lubricant discharged from the compressor can be quickly returned to the compressor together with the working fluid. The risk of running out of lubricant can be reduced. These factors further increase the reliability of the compressor.

"The lubricant and the working fluid are compatible" means that when the lubricant and the working fluid are mixed and left to stand, they do not separate into two layers.
As a lubricant that is compatible with the working fluid, when mixed so that the ratio of the lubricant to the total mass of the working fluid and lubricant is 60% by mass or more, the working fluid always remains at -10°C to 60°C. A lubricant that is compatible with is preferred. Thereby, by mixing the lubricant with the working fluid, the lubricant can be stably supplied to the polymer brush using the working medium. Therefore, it is possible to achieve both improved compressor efficiency and long-term reliability in a wide range of usage environments.

Combinations of such working fluids and lubricants include chlorine-free hydrocarbon refrigerants, carbon dioxide, saturated fluorohydrocarbon refrigerants, unsaturated fluorohydrocarbon refrigerants, and fluorine-containing ether refrigerants. A combination of at least one working fluid selected from the group and at least one lubricant selected from the group consisting of mineral oil, polyol ester oil, polyvinyl ether oil, alkylene glycol oil, and polyalphaolefin oil is preferred. This makes it easy to form a polymer brush with excellent lubricity and chemical stability, and excellent long-term reliability.

Specific examples of operating fluids include propane, propylene, normal buttan, 2 -methyl buttan, isobutan, refrigerant carbon dioxide (R744), HFC23, HFC32, HFC125, HFC134A, HFC143A, HFC410A (R410A). , HFO1225YE, HFO1233ZD, Examples include HFO1233yd, HFO1234yf, HFO1234ze, HFO1234ye, HFO1243zf, HFE245mc, and HFE143m.

Specific examples of the lubricant include polyol ester oil (POE), which has a kinematic viscosity of 74 mm ² /s at 40°C and 8.7 mm ² /s at 100°C, and a kinematic viscosity of 68 mm ² /s at 40°C. , polyvinyl ether oil (PVE) with a kinematic viscosity of 8 mm ² /s at 100°C, polyalkylene glycol oil (PAG) with a kinematic viscosity of 105 mm ² /s at 40°C, and 20 mm ² /s at 100°C. , mineral oil having a kinematic viscosity of 10 mm ² /s at 40°C and 2.3 mm ² /s at 100°C.

Examples of the polymer forming the polymer brush include poly(methyl methacrylate) (PMMA), poly(lauryl methacrylate) (PLMA), and poly(N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium).・Bis(trifluoromethylsulfonyl)imide) (PDEMM-TFSI) and the like. The number of polymers forming the polymer brush may be one, or two or more.

When the polymer brush is swollen with a lubricant, the combination of the polymer and lubricant forming the polymer brush is preferably a combination of PLMA and a refrigerating machine oil selected from polyol esters and polyvinyl ethers. Since PLMA and these refrigerating machine oils have excellent affinity, it becomes easy to swell the polymer brush.

When the polymer brush is swollen with a lubricant, the polymer forming the polymer brush is preferably PMMA, since a non-polar lubricant can be applied. Non-polar lubricants have less adverse effect on metal materials, organic materials, etc. used in the compressor, and can provide a compressor with higher reliability.

The polymer brush can be provided, for example, by grafting a plurality of polymers onto the second sliding surface. A known method can be used for grafting each polymer in the polymer brush.
It is preferable that the polymer forming the polymer brush has a reactive functional group for bonding to the base material and is grafted via bonding using the functional group. Examples of the reactive functional group include hydrolyzable silyl groups such as dialkoxysilyl group and trialkoxysilyl group.

In the polymer brush, it is preferable that the polymer is grafted via an oxide containing silicon. This allows the polymer brush to be formed more effectively, making it easier to effectively demonstrate the tribology and toughness of the polymer brush. Therefore, the effect of reducing friction loss due to low friction is easily obtained, and the efficiency of the compressor is improved.

More specifically, on the second sliding surface, the base material surface is coated with a silicon-containing oxide, and a polymer having a hydrolyzable silyl group at the end is bonded to the silicon-containing oxide through a siloxane bond. Preferably, it is grafted. For example, after coupling an oxide containing silicon coated on the surface of a base material with a coupling agent having a polymerization initiating group such as a bromo group, performing atom transfer radical polymerization (ATRP) in a solution. can form a polymer brush.

Examples of the silicon-containing oxide include tetramethoxysilane, tetraethoxysilane, ethoxytrimethoxysilane, dimethoxydiethoxysilane, and methoxytriethoxysilane. As the oxide containing silicon, one type may be used alone, or two or more types may be used in combination.

Examples of the coupling agent having a polymerization initiating group include (3-trimethoxysilyl)propyl-2-bromo-2-methylpropionate. As the coupling agent having a polymerization initiating group, one type may be used alone, or two or more types may be used in combination.

Preferably, the polymer brush has a crosslinked structure. Since the polymer brush has a crosslinked structure, the tribology and toughness of the polymer brush can be effectively exhibited, and the effect of reducing friction loss due to low friction is enhanced.

Examples of the crosslinking group for forming a crosslinked structure include an azide group and a halogen group (preferably a bromo group). The polymer may have a crosslinking group in its main chain, or if it has a branched chain, it may have a crosslinking group in the branched chain. An unreacted reactive group generated in the main chain when forming a branched chain may be used as a crosslinking group, or a reactive group remaining at the end of the branched chain when a branched chain is formed by living radical polymerization may be used as a crosslinking group. It's okay.

The crosslinked structure may be a physical crosslink or a chemical crosslink. Physical crosslinking and chemical crosslinking may be introduced during polymerization to form a polymer brush (in-situ crosslinking) or after polymerization.
For example, when chemical crosslinking is introduced by in-situ crosslinking, an appropriate amount of a difunctional monomer such as a divinyl monomer (ethylene glycol dimethacrylate, etc.) may be added in addition to the monomer (monofunctional) during polymerization. The amount of the difunctional monomer to be added may be appropriately set, and can be set to, for example, 1 mol % based on the total amount of monomers.

Even if a polymer brush having a crosslinked structure is cut out from the surface of a base material, it will not dissolve in a good solvent (eg, o-dichlorobenzene). This makes it possible to confirm that the polymer is sufficiently crosslinked. Furthermore, when the degree of swelling of the polymer brush is measured by AFM colloid probe method in a good solvent, the degree of swelling is lower than that in a non-crosslinked state, which also confirms that sufficient crosslinking has been formed.

The graft density of the polymer forming the polymer brush is preferably set so that the polymer brush exhibits high lubricity. The graft density can be appropriately set depending on the type of polymer used, the type of solvent, etc.

When the polymer is PMMA, the graft density is preferably 0.1 chain/nm ² or more, more preferably 0.15 chain/nm ² or more, even more preferably 0.2 chain/nm ^{2 or} more, and 0.3 chain/nm 2 or more. It is particularly preferably at least 0.4 strands/nm ² , most preferably ^at least 0.45 strands/nm ² .

When the polymer is PLMA, the graft density is preferably 0.04 chains/nm ² or more, more preferably 0.06 chains/nm ² or more, even more preferably 0.08/nm ² or more, and 0.12 chains/nm 2 or more. ² or more is particularly preferred, 0.16 chains/nm ² or more is extremely preferred, and 0.18 chains/nm ² or more is most preferred.

When the polymer is PDEMM-TFSI, the graft density is preferably 0.02 chains/nm ² or more, more preferably 0.03 chains/nm ² or more, even more preferably 0.04 chains/nm 2 or more, and 0.06 chains/nm ² or more. Chains/nm ² or more are particularly preferred, 0.08 chains/nm ² or more are extremely preferred, and 0.09 chains/nm ² or more are most preferred.

Graft density of polymers can be measured according to known methods. For example, it can be measured according to the methods described in Macromolecules, 31, 5934-5936 (1998), Macromolecules, 33, 5608-5612 (2000), Macromolecules, 38, 2137-2142 (2005), etc.
Specifically, the graft density σ (chains/nm ² ) is determined by measuring the amount of grafting (W), which is the amount of polymer forming the polymer brush, and the number average molecular weight (Mn) of the polymer (grafted chains), and calculating the following: It can be determined from equation (4).
σ (chain/nm ² )=W (g/nm ² )/Mn×(Avogadro's number) (4)

When the surface of the base material forming the polymer brush is flat, the amount of grafting (W) can be calculated per unit area by measuring the dry thickness of the polymer brush using the ellipsometry method and using the measured value and bulk density. The amount of grafting can be calculated. When the material of the surface of the base material forming the polymer brush is silica, the amount of grafting (W) can also be measured by infrared absorption spectroscopy (IR), thermogravimetric loss measurement (TG), elemental analysis measurement, etc. can.

Specifically, the graft density σ is determined by, for example, the slope of a graph plotting the thickness of the polymer brush in a dry state and the Mn of the polymer (see, for example, Japanese Patent Application Laid-Open No. 11-263819), the amount of grafting of the polymer in the polymer brush, etc. It can be determined from the slope of a graph plotting Mn and Mn of the polymer.

The ratio of the occupied area of the polymer forming the polymer brush to the area of the region where the polymer brush is formed on the second sliding surface (the ratio of the occupied area of the polymer per cross-sectional area of the cross section perpendicular to the thickness direction of the polymer brush) ) σ ^* is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more. If the occupied area ratio σ ^* is equal to or higher than the lower limit value, the tribological properties of the polymer brush will improve and the toughness (resiliency) will be improved, resulting in a polymer brush with excellent durability. The compressor can be applied to various usage environments and applications.

The occupied area ratio σ ^* means the ratio occupied by the graft point (the first monomer of the polymer) in the region of the second sliding surface where the polymer brush is formed. In the polymer brush, the occupied area ratio σ ^* is 100% in a state where each polymer is most closely packed, that is, in a state where no more polymers can be grafted.
The occupied area ratio σ ^* is calculated by determining the cross-sectional area perpendicular to the thickness direction of the polymer brush from the repeating unit length in the fully extended form of the polymer and the bulk density of the polymer, and multiplying this by the graft density σ can.

Mn of the polymer forming the polymer brush can be set so as to exhibit desired lubricity, and is preferably 500 to 10,000,000, more preferably 100,000 to 10,000,000.
The molecular weight distribution index (Mw/Mn) can be set to exhibit desired lubricity, and is preferably 1.5 or less, more preferably 1.01 to 1.5.

The number average molecular weight (Mn) and weight average molecular weight (Mw) of the polymer forming the polymer brush are determined by the hydrogen fluoride After the polymer (graft chain) is cut out from the graft point by acid treatment, it can be measured by gel permeation chromatography (GPC).

The Mn and Mw of the polymer forming the polymer brush are approximately equal to the Mn and Mw of the free polymer obtained by polymerization under the same conditions as those used to form the polymer brush. For example, by adding a free initiator to a polymerization solution used to form a polymer brush, a free polymer having Mn and Mw equivalent to those of the polymer forming the polymer brush can be obtained. The Mn and Mw of this free polymer may be measured by the GPC method, and may be determined as the Mn and Mw of the polymer forming the polymer brush.
In the GPC method, a calibration method using a standard sample obtained by monodispersing an available polymer with a known molecular weight and an absolute molecular weight evaluation using a multi-angle light scattering detector are performed.

The average length of the polymer forming the polymer brush can be set so as to exhibit desired lubricity, and is preferably 0.5 μm or more, more preferably 0.7 μm or more, even more preferably 0.8 μm or more, and 1.0 μm or more. is particularly preferred. If the average length of the polymer is equal to or greater than the lower limit, the tribological properties of the polymer brush will be improved and the toughness (resiliency) will be improved, resulting in a polymer brush with excellent durability. Therefore, the compressor can be applied to various usage environments and applications.
The upper limit of the average length of the polymer can be set as appropriate within a range that does not impair the function of the compressor, and can be set to, for example, 5 μm.
The average length of the molecular chains of a polymer can be determined from, for example, Mn and Mw/Mn of the polymer.

It is particularly preferable that the polymer brush is a thick-film concentrated polymer brush made of a polymer having an average molecular chain length of 0.5 μm or more and having an area ratio σ ^* of the polymer on the sliding surface of 10% or more. .

According to the embodiment described above, since the polymer brush is provided on the second sliding surface, which has a small area in the compression mechanism section and has a high risk of wear, it is possible to effectively suppress wear on the sliding surface. Furthermore, friction loss can be efficiently and stably reduced over a long period of time.

Although the embodiments of the present invention have been described, the embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

The first sliding surface and the second sliding surface in the compression mechanism section are not limited to the inner circumferential surface of the cylinder and the tip surface of the vane. For example, the first sliding surface may be the lower surface of the main bearing 42, and the second sliding surface may be the upper end surface of the vane 48. The first sliding surface may be the upper surface of the secondary bearing 43, and the second sliding surface may be the lower end surface of the vane 48. The first sliding surface may be the lower surface of the main bearing 42, and the second sliding surface may be the upper end surface of the piston 46. The first sliding surface may be the upper surface of the secondary bearing 43, and the second sliding surface may be the lower end surface of the piston 46.

The compressor is not limited to a vane type compressor, and may be, for example, a reciprocating type compressor 6 (hereinafter referred to as "compressor 6") illustrated in FIG. 6.
The compressor 6 includes a compression mechanism section 101 that includes a cylinder 110 and a piston 111 that is reciprocatably housed within the cylinder 110. A suction valve 112 and a discharge valve 113 are provided at the top of the cylinder 110.

In the compressor 6, when the piston 111 descends within the cylinder 110, the suction valve 112 opens, and working fluid flows into the working chamber 114 formed by the cylinder 110 and the piston 111. Further, when the piston 111 rises, the working fluid is compressed within the working chamber 114, and when the inside of the working chamber 114 reaches a pressure equal to or higher than that of the external space of the cylinder 110, the discharge valve 113 opens and the working fluid flows into the cylinder 110. Discharged to the outside.

In the compressor 6, the inner peripheral surface 110a of the cylinder 110 and the outer peripheral surface 111a of the piston 111 slide against each other. The area of the outer circumferential surface 111a of the piston 111 is smaller than the inner circumferential surface 110a of the cylinder 110, the inner circumferential surface 110a of the cylinder 110 is the first sliding surface, and the outer circumferential surface 111a of the piston 111 is the second sliding surface. including. In the compressor 6, a polymer brush 80 is provided on the outer peripheral surface 111a of the piston 111.

By providing the polymer brush 80 on the outer peripheral surface 111a of the piston 111, which has a smaller area, longer sliding contact time with the mating sliding surface, and has harsher friction conditions, wear on the sliding surface can be effectively suppressed. . Further, by providing the polymer brush 80 on the outer circumferential surface 111a of the piston 111, which is difficult to supply and hold lubricant to, the lubricant can be easily supplied to and held on the outer circumferential surface 111a of the piston 111. Therefore, it becomes easier to stably obtain the effect of reducing wear on the sliding surfaces, resulting in a highly reliable compressor 6 that can efficiently and stably reduce friction loss over a long period of time.

As shown in FIG. 7, in this embodiment, the upper part of the piston 111 is reduced in diameter, and the upper part of the outer circumferential surface 111a of the piston 111 is inclined so as to move away from the inner circumferential surface 110a of the cylinder 110 toward the upper end. In this case, the outer circumferential surface 111a of the piston 111 has a second sliding surface 111b that slides into contact with the inner circumferential surface 110a of the cylinder 110 via a lubricating oil film at the initial stage of sliding, and an upper side (high pressure) of the second sliding surface 110b. 110c).

In the compression mechanism section 101, the outer circumferential surface 111a of the piston 111 is in sliding contact with the inner circumferential surface 110a of the cylinder 110, and a high-pressure working chamber 114 in the cylinder 110 and a low-pressure external space are divided. In this way, the inner peripheral surface 110a (first sliding surface) of the cylinder 110 and the second sliding surface 111b on the outer peripheral surface 111a of the piston 111 are a sealing surface that divides and seals the working fluid with a pressure difference. There is also.

On the outer peripheral surface 111a of the piston 111, a polymer brush 80 is provided over the entire outer peripheral surface 111a. That is, on the outer circumferential surface 111a of the piston 111, the polymer brush 80 is provided not only on the second sliding surface 111b but also on the non-sliding surface 111c on the high pressure side surrounding the second sliding surface 111b. As a result, even if the lubricant on the second sliding surface 111b decreases, the lubricant held in the polymer brush 80 on the high-pressure side non-sliding surface 111c is transferred to the second sliding surface 111b due to the differential pressure. Since the lubricant is supplied, the compressor 6 becomes even more reliable and can cope with lubricant shortages.
Note that a configuration may also be adopted in which the polymer brush is not provided on the non-sliding surface around the second sliding surface.

Further, other preferable embodiments of providing the polymer brush on the second sliding surface described in connection with the compressor 2 are also applicable to a reciprocating compressor such as the compressor 6.

The present invention will be specifically explained below using examples, but is not limited by the following description. In addition, "part" in the following description means "part by mass."

[Accelerated evaluation test of sliding reliability]
A block-on-ring tester 200 shown in FIG. 8 was prepared. The block-on-ring tester 200 includes a case 201 in which a refrigerant 202 and a lubricant 203 are sealed, and a ring 204 rotatably provided in the case 201 with a portion immersed in the lubricant 203. It is equipped with While pressing the block 205 from above the ring 204 with a predetermined load F, the ring 204 is rotated at a predetermined speed and the wear depth (maximum depth) of the sliding surface 205a of the block 205 is measured. The dynamic reliability was evaluated. As the ring 204 rotates, the lubricant 203 adhering to the outer peripheral surface 204a of the ring 204 is supplied to the sliding contact portion between the ring 204 and the block 205. When the ring 204 and the block 205 slide, the outer circumferential surface 204a of the ring 204 is the first sliding surface, and the sliding surface 205a of the block 205 that makes sliding contact with the ring 204 is the second sliding surface.
R410A and polyol ester oil (POE) were used as the compatible refrigerant 202 and lubricant 203. The kinematic viscosity of the lubricant 203, the pressure of the refrigerant 202 in the case 201, and the test temperature (temperature of the lubricant) are adjusted so that the actual kinematic viscosity of the lubricant 203 is comparable to that of the sliding parts of the compressor during operation. Adjusted. The test conditions are shown in Table 1.

Note that "actual viscosity" in Table 1 is the kinematic viscosity at the sliding contact portion between the ring and the block during the test. "Ring outer circumferential speed" is the speed at the portion of the outer circumferential surface of the rotating ring that makes sliding contact with the block. The length of the sliding contact portion is the length of the portion where the ring and the block are in sliding contact in the rotational axis direction of the ring (the length direction of the sliding portion that is in linear sliding contact).

The block 205 was made of SUS440C, and the sliding surface 205a was subjected to gas nitriding treatment as a surface hardening treatment, and the surface hardness of the sliding surface 205a was set to 1000 HV in terms of Vickers hardness. The ring 204 is made of monochromatic cast iron, which is gray cast iron to which Mo, Ni, Cr, etc. are added, and the surface hardness of the outer peripheral surface 204a is 510 HV in terms of Vickers hardness. Table 2 shows the specifications of the ring 204 and block 205.

[ ¹ H-NMR measurement]
In the ¹ H-NMR measurement, a Fourier transform nuclear magnetic resonance apparatus FT-NMR ("JNM-ECA600" or "ECA400" manufactured by JEOL RESONANCE Co., Ltd.) was used. Heavy chloroform (manufactured by Wako Pure Chemical Industries, Ltd.) was used as a heavy solvent.

[Gel permeation chromatography (GPC)]
In the molecular weight measurement by the GPC method, "Shodex GPC-101" manufactured by Showa Denko K.K. was used as a molecular weight measuring device, and two columns ("Shodex KF-806L" manufactured by Showa Denko K.K.) were connected in series. Tetrahydrofuran (THF) was used as the eluent. Measurements were performed at 40° C., and the flow rate was 0.8 mL/min. Mn and Mw/Mn were determined using a PMMA-converted calibration curve obtained by using PMMA (manufactured by VARIAN) with a known molecular weight as a calibration sample.

[Dry film thickness of polymer brush]
A spectroscopic ellipsometer ("M-2000U" manufactured by JA Woollam Japan Co., Ltd.) was used to measure the dry film thickness of the polymer brush. A deuterium and quartz tungsten halogen (QTH) lamp was used as a light source.

[Experiment example 1]
Block 205 was ultrasonically cleaned with a mixed solvent of acetone and hexane in a mass ratio of 1:1 for 30 minutes, then with chloroform for 30 minutes, then with 2-propanol for 30 minutes, and treated with a UV ozone cleaner for 30 minutes. The washed block 205 was immersed in 34.8 parts of ethanol.
Prepare a solution of 0.54 parts of tetraethoxysilane (TEOS) and 17.8 parts of ethanol in a sample container with a lid, and prepare a solution of 1.3 parts of 28% aqueous ammonia and 17.8 parts of ethanol in another sample container. and mixed them. The washed block 205 was added to the mixed solution along with 34.8 parts of ethanol and reacted at room temperature (25° C.) for 24 hours.The block 205 was then taken out from the reaction solution and ultrasonically cleaned with ethanol. A block 205 coated with silica was obtained.

The silica-coated block 205 was ultrasonically cleaned with a mixed solvent of acetone and hexane in a mass ratio of 1:1 for 30 minutes, then with chloroform for 30 minutes, then with 2-propanol for 30 minutes, and treated with a UV ozone cleaner for 30 minutes.
In a sample container with a lid, prepare a solution of 0.5 parts of (3-trimethoxysilyl)propyl-2-bromo-2-methylpropionate and 22.3 parts of ethanol, and in another sample container, prepare a solution of 5 parts of 28% ammonia water. A solution of .7 parts and 25.4 parts of ethanol was prepared and mixed. The washed block 205 coated with silica is immersed in the mixed solution, a silane coupling reaction is carried out at room temperature (25° C.) for 24 hours, and then the block 205 is taken out from the reaction solution and ultrasonically cleaned with ethanol. A block 205 having a polymerization initiating group immobilized on the sliding surface 205a was obtained.

In the glove box, 0.00026 parts of ethyl-2-bromo-2-methylpropionate and 36.0 parts of lauryl methacrylate (SLMA, Bremmer SLMA-S manufactured by NOF Corporation) were placed in a pressure-resistant container made of Teflon (registered trademark). 1 part, 0.21 part of copper(I) bromide, 0.014 part of copper(II) bromide, 1.2 parts of 4,4'-dinonyl-2,2'-bipyridyl, and 37.5 parts of anisole were added. did. Next, the block 205 on which the polymerization initiating group was immobilized was placed in a pressure-resistant container, the container was covered, and SI-ATRP was performed at 600 C and 400 MPa for 2 hours. After the polymerization was completed, the blade was taken out from the polymerization solution and thoroughly washed with THF to obtain a block 205 with a thick film PLMA brush provided on the sliding surface 205a.

After polymerization, the polymerization solution was subjected to molecular weight measurement using ¹ H-NMR measurement and GPC method, and the Mn and Mw/Mn of free PLMA were calculated. As a result, Mn was 4.6×10 ⁶ and Mw/Mn was 1.23. Met.
Furthermore, during polymerization, a silicon wafer on which a polymerization initiating group was immobilized in the same manner as in the case of the blade was also added to the polymerization solution and used as a reference for film thickness measurement. When the dry film thickness of a PLMA brush formed on a silicon wafer was analyzed by ellipsometry, it was found to be 1.10 μm. Furthermore, when the graft density σ and the occupied area ratio σ ^* were calculated from the obtained data, the graft density σ was 0.20 chains/nm ² and the occupied area ratio σ ^* was 38%.

Using a block 205 in which a thick film PLMA brush was provided on the sliding surface 205a, an accelerated test was conducted using a block-on-ring tester 200 with a load F of 150 N, and the wear depth of the sliding surface 205a was measured. 2F/πLA calculated using A determined by equation (2) from the numerical values in Tables 1 and 2 was 171 MPa.

[Experiment example 2]
An accelerated test was conducted with the load F at 150 N in the same manner as in Experimental Example 1, except that the block 205 without a polymer brush on the sliding surface 205a was used, and the depth of wear on the sliding surface 205a was measured.

[Experiment example 3]
Using a block 205 in which a thick film PLMA brush was provided on the sliding surface 205a, an accelerated test was conducted using a block-on-ring tester 200 with a load F of 300 N, and the wear depth of the sliding surface 205a was measured. 2F/πLA calculated using A determined by equation (2) from the values in Tables 1 and 2 was 242 MPa.

[Experiment example 4]
An accelerated test was conducted in the same manner as in Experimental Example 1, except that the block 205 without a polymer brush on the sliding surface 205a was used and the load F was 300 N, and the depth of wear on the sliding surface 205a was measured.
FIG. 9 shows the measurement results of the wear depth of the sliding surface 205a in each experimental example.

As shown in FIG. 9, Experimental Example 1 in which a polymer brush was provided on the sliding surface 205a of the block 205 had a smaller wear depth and superior sliding reliability than Experimental Example 2 in which a polymer brush was not provided. Ta. Similarly, in Experimental Example 3 in which a polymer brush was provided on the sliding surface 205a of the block 205, the wear depth was smaller than in Experimental Example 4 in which no polymer brush was provided, and the sliding reliability was excellent. Furthermore, Experimental Example 1 in which the value of 2F/πLA was less than 240 MPa was more effective in suppressing wear on the sliding surface than Experimental Example 3 in which the value of 2F/πLA was more than 240 MPa.

[Experiment example 5]
FIG. 10 shows a two-layer separation temperature diagram of R410A, which is a working fluid, and POE, which is a lubricant (refrigerating machine oil), from -10°C to 60°C.
As shown in Figure 10, in the temperature range from -10°C to 60°C, there is a region where the working fluid (refrigerant) and lubricant (refrigerating machine oil) separate into two layers. When the proportion of the lubricant was 60% by mass or more, compatibility was always observed.

1... Refrigeration cycle device, 2... Compressor, 3... Condenser (radiator), 4... Expansion device, 5... Evaporator (heat absorber), 6... Reciprocating type compressor, 31... Drive shaft, 33... Compression mechanism Part, 34... Airtight container, 41... Cylinder, 41a... Inner peripheral surface (first sliding surface), 42... Main bearing (closure plate), 43... Sub bearing, 45... Working chamber, 45a... Suction chamber, 45b ...Compression chamber, 46...Piston, 47...Vane slot, 48...Vane, 48a...Top surface, 48b...Second sliding surface, 48c...Non-sliding surface, 80...Polymer brush, 101...Compression mechanism section, 110 ...Cylinder, 110a...Inner circumferential surface (first sliding surface), 111...Piston, 111a...Outer circumferential surface, 111b...Second sliding surface, 111c...Non-sliding surface.

Claims (10)

In a compressor having a compression mechanism section that sucks in and discharges working fluid, the compression mechanism section slides on a first sliding surface and has an area larger than the first sliding surface. a second sliding surface with a small diameter, and a polymer brush is provided on the second sliding surface,
There is a portion on the second sliding surface that is different in distance from the first sliding surface,
A compressor, wherein an area ratio occupied by a polymer in a portion where the distance is long in the polymer brush provided on the second sliding surface is higher than an area ratio occupied by the polymer in a portion where the distance is short. In a compressor having a compression mechanism section that sucks in and discharges working fluid, the compression mechanism section slides on a first sliding surface and has an area larger than the first sliding surface. a second sliding surface with a small diameter, and a polymer brush is provided on the second sliding surface,
the polymer brush is swollen with a lubricant that lubricates the compression mechanism, and the lubricant is compatible with the working fluid;
The radii of curvature of the first sliding surface and the second sliding surface are different from each other, and the contact pressure of the first sliding surface and the second sliding surface is expressed by the following formula (1). A compressor that is in linear contact to meet the conditions of

However, in the formula (1), F is the load (N) that the first sliding surface and the second sliding surface receive, and L is the load (N) that the first sliding surface and the second sliding surface receive. It is the length (mm) of the linear sliding contact portion with the moving surface, and A is expressed by the following formula (2).

However, in the formula (2), E1 is the longitudinal elastic modulus (MPa) of the base material forming the first sliding surface, and E2 is the longitudinal elastic modulus (MPa) of the base material forming the second sliding surface. coefficient (MPa), ν1 is the Poisson's ratio of the base material forming the first sliding surface, ν2 is the Poisson's ratio of the base material forming the second sliding surface, and R1 is the linear R2 is the radius of curvature (mm) of the first sliding surface when viewed from the length direction of the linear sliding portion, and R2 is the radius of curvature (mm) of the second sliding surface when viewed from the length direction of the linear sliding portion. is the radius of curvature (mm) of the sliding surface. The radius of curvature is a positive value when the sliding surface is a convex surface, a negative value when the sliding surface is a concave surface, and an infinite value when the sliding surface is a flat surface. There is a portion on the second sliding surface that is different in distance from the first sliding surface,
Compression according to claim 2 , wherein the area ratio of the polymer in the part where the distance is large in the polymer brush provided on the second sliding surface is higher than the area ratio of the polymer in the part where the distance is small. Machine. The compressor according to any one of claims 1 to 3 , wherein the second sliding surface has a higher surface hardness than the first sliding surface. The compressor according to any one of claims 1 to 4 , wherein a surface roughness Ra of the second sliding surface is larger than a surface roughness Ra of the first sliding surface. The compression mechanism includes a cylinder forming a working chamber, a piston rotating within the working chamber, and a plurality of vanes respectively accommodated in a plurality of vane slots formed in the piston, and the compressor mechanism includes a cylinder forming a working chamber, a piston rotating within the working chamber, and a plurality of vanes respectively accommodated in a plurality of vane slots formed in the piston. In a vane type compressor, each of the vanes slides within the vane slot, and the tip surface of the vane and the inner circumferential surface of the piston slide, so that the working chamber is divided into a suction chamber and a compression chamber. 6. The compressor according to claim 1, wherein the polymer brush is provided on the tip surface of the vane, which is the second sliding surface. In a reciprocating compressor comprising a compression mechanism including a cylinder and a piston reciprocably housed in the cylinder, the second sliding surface is a sliding surface of the piston on the inner circumferential surface of the cylinder. The compressor according to any one of claims 1 to 5 , wherein the polymer brush is provided on a moving outer peripheral surface. The compressor according to any one of claims 1 to 7 , wherein the polymer brush is provided up to a non-sliding surface around the second sliding surface. The first sliding surface and the second sliding surface that slide against each other are sealing surfaces that divide and seal the working fluid having a pressure difference, and at least the high pressure side of the second sliding surface The compressor according to claim 8 , wherein the polymer brush is provided on the non-sliding surface of the compressor. A compressor according to any one of claims 1 to 9 , a radiator connected to the compressor, an expansion device connected to the radiator, and an evaporator connected to the expansion device. Equipped with refrigeration cycle equipment.

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