Sealed refrigerant compressor, operating method therefor, and freezing and refrigeration device using the same

Abstract

To provide a sealed refrigerant compressor capable of realizing further excellent coefficient of performance (COP), using refrigeration oil with lower viscosity.SOLUTION: In a sealed refrigerant compressor, refrigeration oil having a kinetic viscosity at 40°C in a range of 1.0 mm2 / s to 2.5 mm2 / s is stored inside a sealed container. A ratio of a reciprocating stroke amount of a piston 140 to a piston diameter is within a range of 0.78 to 1.00. A length of an area sealed in a compression chamber by the reciprocating motion of the piston is a seal length of the piston. A ratio of the overall piston length to the piston diameter is within a range of 0.8 to 1.0, and a ratio of the seal length to the overall piston length is within a range of 0.9 to 1.0. Further, when an operating frequency is 16 r / s or more and 35 r / s or less, an average reciprocating speed of the piston is set to beyond 0.31 m / s.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a hermetic refrigerant compressor used in a refrigerator, an air conditioner, etc., an operation method of the hermetic refrigerant compressor, and a refrigeration / refrigeration device using the hermetic refrigerant compressor.

Background Art

[0002] In recent years, from the viewpoint of global environmental protection, the development of a highly efficient hermetic refrigerant compressor with reduced input power by reducing the use of fossil fuels has been promoted. To reduce the input power of a hermetic refrigerant compressor, reducing the operating frequency is an effective means.

[0003] On the other hand, regarding high efficiency, the coefficient of performance (COP) represented by refrigerating capacity / input power is an index indicating the efficiency of a hermetic refrigerant compressor. In order to improve the coefficient of performance (COP), for example, it has been proposed to use oil with a lower viscosity (refrigerating machine oil, lubricating oil). For example, Patent Document 1 discloses a refrigerant compressor that aims to improve efficiency by setting the viscosity of the oil stored inside the hermetic container to be 3 or more and 8 or less in VG.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, in recent years, in order to further improve the coefficient of performance (COP), it has been considered to further reduce the viscosity of the refrigeration oil. For example, in the refrigerant compressor disclosed in Citation Document 1, the viscosity of the oil (refrigeration oil) is in the range of VG3 to VG8 as described above, but in recent years, the use of refrigeration oil with a viscosity of VG3 or less has also been considered. However, simply using a lower-viscosity refrigeration oil to further reduce the sliding loss is not sufficient to further improve the coefficient of performance (COP).

[0006] The present invention has been made to solve such problems, and an object thereof is to provide a hermetic refrigerant compressor, an operation method thereof, and a refrigeration / air-conditioning apparatus using the same, which can achieve a better coefficient of performance (COP) by using a lower-viscosity refrigeration oil.

Means for Solving the Problems

[0007] The hermetic refrigerant compressor according to the present disclosure, in order to solve the above problems, includes a hermetic container, a refrigeration oil stored in the hermetic container and having a kinematic viscosity at 40°C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block accommodated in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber. When the operating frequency is 16 r / s or more and 35 r / s or less, it is sufficient that the average speed of the reciprocating motion of the piston is set to exceed 0.31 m / s.

[0008] According to the above configuration, when the operating frequency of the hermetic refrigerant compressor is 16 r / s or more and 35 r / s or less, the lower limit of the average speed of the reciprocating motion of the piston (piston average speed) is set. Thereby, even when the operating speed of the hermetic refrigerant compressor is relatively low, the piston average speed can be relatively high. Therefore, as the refrigeration oil, the viscosity is further reduced (the kinematic viscosity at 40°C is 1.0 mm 2 / s to 2.5 mm 2Even when using a low-viscosity oil set within the range of / s, a good oil film can be formed between the piston that reciprocates at high speed and the compression chamber. As a result, leakage of refrigerant gas from the piston and the compression chamber can be suppressed well. Therefore, when using low-viscosity oil as refrigeration oil, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0009] Also, in order to solve the above problems, the hermetic refrigerant compressor according to the present disclosure includes a hermetic container, refrigeration oil stored in the hermetic container and having a kinematic viscosity at 40 °C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block accommodated in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber, and a ratio S / D of a stroke amount (S) of reciprocation of the piston to the piston diameter (D) may be in the range of 0.78 to 1.00.

[0010] According to the above configuration, when using low-viscosity oil having a kinematic viscosity at 40 °C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s as refrigeration oil, the ratio S / D is set within a predetermined range. Thereby, since the stroke amount (S) can be relatively increased, the piston average speed can be relatively increased. Therefore, the leakage amount of refrigerant gas can be suppressed well.

[0011] Also, when using the above low-viscosity oil as refrigeration oil, by setting the ratio S / D within a predetermined range, the piston diameter (D) can be relatively reduced. Thereby, since the total area of the clearance between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder can be reduced, leakage of refrigerant gas can be suppressed well.

[0012] Furthermore, if the piston diameter (D) becomes relatively small, the compression load of the refrigerant gas on the piston can be reduced. Thereby, the input power for reciprocating the piston can be reduced.

[0013] Therefore, by setting the ratio S / D within a predetermined range, when a low-viscosity oil is used as the refrigeration oil, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0014] In addition, in order to solve the above problems, the hermetic refrigerant compressor according to the present disclosure includes a hermetic container, a refrigeration oil stored in the hermetic container and having a kinematic viscosity at 40°C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block housed in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber. The ratio L1 / D of the total length (L1) of the piston to the piston diameter (D) is in the range of 0.8 to 1.0, and when the length of the region where the piston seals the inside of the compression chamber by its reciprocating motion is defined as the seal length (L2), the ratio L2 / L1 of the seal length (L2) to the total length (L1) of the piston may be in the range of 0.9 to 1.0.

[0015] According to the above configuration, when a low-viscosity oil having a kinematic viscosity at 40°C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s is used as the refrigeration oil, the ratios L1 / D and L2 / L1 are set within a predetermined range. Thereby, while suppressing an increase in sliding loss, the seal length (L2) can be relatively increased without excessively increasing the total length (L1) of the piston. Therefore, between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder, the viscous force of the oil film can be increased while suppressing an increase in sliding loss.

[0016] In addition, between the piston and the cylinder, the region sealed by the oil film of the refrigeration oil can also be relatively increased. Therefore, the leakage of the refrigerant gas can be further suppressed.

[0017] Furthermore, if the seal length (L2) increases, it becomes possible to stabilize the posture of the piston reciprocating in the compression chamber. As a result, it also becomes possible to further suppress an increase in sliding loss.

[0018] Therefore, by setting the ratios L1 / D and L2 / L1 within a predetermined range, when using a low-viscosity oil as the refrigeration oil, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0019] In addition, in order to solve the above problems, the operation method of the hermetic refrigerant compressor according to the present disclosure includes a hermetic container, a refrigeration oil stored in the hermetic container and having a kinematic viscosity at 40 °C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block accommodated in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber. In the hermetic refrigerant compressor, when the operating frequency is 16 r / s or more and 35 r / s or less, the average speed of the reciprocating motion of the piston may exceed 0.31 m / s.

[0020] In addition, the refrigeration and refrigeration device according to the present disclosure may include the hermetic refrigerant compressor having the above configuration, a radiator, a decompression device, and an absorber, and may have a configuration in which these are annularly connected by piping to form a refrigerant circuit.

[0021] The above objects, other objects, features, and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments with reference to the accompanying drawings.

Effects of the Invention

[0022] In the present invention, with the above configuration, it is possible to provide a hermetic refrigerant compressor, an operation method thereof, and a refrigeration and refrigeration device using the same, which can achieve a better coefficient of performance (COP) by using a lower-viscosity refrigeration oil.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

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Figure 10

MODE FOR CARRYING OUT THE INVENTION

[0024] (Findings and the like that form the basis of the present disclosure) In a hermetic refrigerant compressor, a compression chamber is formed in a cylinder provided in a cylinder block, and a piston is inserted into the compression chamber so as to be reciprocable. Refrigerant oil exists as an oil film between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder (inner peripheral surface of the compression chamber), and lubricates the reciprocating motion (i.e., sliding motion) of the piston. For the sake of convenience of explanation, the space between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder is abbreviated as "between piston and cylinder". If the kinematic viscosity of the refrigerant oil decreases, the oil film formed between the piston and the cylinder becomes thinner. Although it becomes possible to reduce the sliding loss associated with the reciprocating motion (sliding motion) of the piston by the thinning of the oil film, it is also assumed that refrigerant gas may leak from between the piston and the cylinder.

[0025] As will be described in the embodiments below, the present inventors used refrigerant oils having different kinematic viscosities at 40°C under the condition of an operating frequency as low as 17 r / s (rps) in a hermetic refrigerant compressor having the configuration of the conventional example, and experimentally verified and evaluated the amount of refrigerant gas leaking from between the piston and the cylinder. As a result, it became clear that when the kinematic viscosity of the refrigerant oil at 40°C is 2.5 mm 2 / s or less, the amount of refrigerant gas leakage increases.

[0026] Based on this verification and evaluation, in the refrigerant oil used, the lower the kinematic viscosity at 40°C, the more the amount of refrigerant gas leakage tends to increase. However, even if the viscosity of the refrigerant oil is reduced, as long as it reaches 2.5 mm 2 / s, it is considered that the sliding loss in the hermetic refrigerant compressor can be effectively reduced more than the influence of the increase in the amount of refrigerant gas leakage, and as a result, the coefficient of performance (COP) can be improved.

[0027] However, if the kinematic viscosity of the refrigerant oil at 40°C is 2.5 mm 2 / s or less, the amount of refrigerant gas leakage becomes too large. Therefore, it has become clear that the refrigerating capacity of the refrigeration cycle equipped with the hermetic refrigerant compressor decreases, and as a result, the coefficient of performance (COP) cannot be improved.

[0028] If it becomes possible to satisfactorily suppress the leakage of refrigerant gas from between the piston and the cylinder in a state where the kinematic viscosity of the refrigerating machine oil is reduced, a further improvement in the coefficient of performance (COP) can be expected in a hermetic refrigerant compressor. However, it is difficult to achieve both the reduction of the viscosity of the refrigerating machine oil and the suppression of the leakage amount of the refrigerant gas.

[0029] Therefore, as a result of further intensive studies by the present inventors, it has been found that by effectively suppressing the leakage of refrigerant gas from between the piston and the cylinder, it is possible to improve the coefficient of performance (COP), and the present invention has been completed.

[0030] That is, the hermetic refrigerant compressor according to the present disclosure includes a hermetic container, refrigerating machine oil stored in the hermetic container and having a kinematic viscosity at 40 ° C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block accommodated in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber. When the operating frequency is 16 r / s or more and 35 r / s or less, the average speed of reciprocating motion of the piston may be configured to exceed 0.31 m / s.

[0031] According to the above configuration, when the operating frequency of the hermetic refrigerant compressor is 16 r / s or more and 35 r / s or less, the lower limit of the average speed of reciprocating motion of the piston (piston average speed) is set. As a result, even when the operating speed of the hermetic refrigerant compressor is relatively low, the piston average speed can be relatively high. Therefore, as the refrigerating machine oil, even if a lower viscosity oil (set within the range of 1.0 mm 2 / s to 2.5 mm 2 / s at 40 ° C) is used, a good oil film can be formed between the reciprocating piston and the compression chamber. As a result, it becomes possible to satisfactorily suppress the leakage of refrigerant gas from the piston and the compression chamber. Therefore, when the low viscosity oil is used as the refrigerating machine oil, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0032] In the hermetic refrigerant compressor having the above-described configuration, the ratio S / D of the stroke amount (S) of reciprocating movement of the piston to the piston diameter (D) may be in the range of 0.78 to 1.00.

[0033] According to the above-described configuration, in addition to relatively increasing the average piston speed, the ratio S / D is set within the above range. By setting this ratio S / D, as will be described later, the stroke amount (S) can be relatively increased or the piston diameter (D) can be relatively decreased.

[0034] As a result, the leakage amount of the refrigerant gas can be favorably suppressed, and the input power for reciprocating the piston can be reduced. Therefore, when a low-viscosity oil is used as the refrigerating machine oil, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0035] Further, in the hermetic refrigerant compressor having the above-described configuration, when the length of the region where the piston seals the compression chamber by its reciprocating movement is defined as the seal length (L2), the ratio L1 / D of the total piston length (L1) to the piston diameter (D) is in the range of 0.8 to 1.0, and the ratio L2 / L1 of the seal length (L2) to the total piston length (L1) is in the range of 0.9 to 1.0.

[0036] According to the above-described configuration, in addition to relatively increasing the average piston speed, the ratios L1 / D and L2 / L1 are set within a predetermined range. By setting these ratios, as will be described later, the seal length (L2) can be relatively increased without excessively increasing the total piston length (L1).

[0037] As a result, between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder, it is possible to increase the viscous force of the oil film while suppressing an increase in sliding loss, and to further suppress the leakage of the refrigerant gas. Therefore, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0038] Another hermetic refrigerant compressor according to the present disclosure includes a hermetic container, a refrigerating machine oil stored in the hermetic container and having a kinematic viscosity at 40 ° C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block accommodated in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber, and a ratio S / D of a reciprocating stroke amount (S) of the piston to the piston diameter (D) is in the range of 0.78 to 1.00.

[0039] According to the above configuration, when using a low-viscosity oil having a kinematic viscosity at 40 ° C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s as the refrigerating machine oil, the ratio S / D is set within a predetermined range. Thereby, since the stroke amount (S) can be relatively increased, the piston average speed can be relatively increased. Therefore, the leakage amount of the refrigerant gas can be favorably suppressed.

[0040] Also, when using the above low-viscosity oil as the refrigerating machine oil, by setting the ratio S / D within a predetermined range, the piston diameter (D) can be relatively reduced. Thereby, since the total area of the clearance between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder can be reduced, the leakage of the refrigerant gas can be favorably suppressed.

[0041] Furthermore, if the piston diameter (D) becomes relatively small, the compression load of the refrigerant gas on the piston can be reduced. Thereby, the input power for reciprocating the piston can be reduced.

[0042] Therefore, by setting the ratio S / D within a predetermined range, when using a low-viscosity oil as the refrigerating machine oil, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0043] In the hermetic refrigerant compressor having the above-described configuration, when the length of the region where the piston seals the compression chamber by its reciprocating motion is defined as the seal length (L2), a configuration may be adopted in which the ratio L2 / L1 of the seal length (L2) to the total length (L1) of the piston is in the range of 0.9 to 1.0.

[0044] According to the above-described configuration, in addition to setting the ratio S / D of the stroke amount (S) of the piston to the piston diameter (D) within a predetermined range, the ratios L1 / D and L2 / L1 are set within a predetermined range. By setting these ratios, as will be described later, the seal length (L2) can be relatively increased without excessively increasing the total length (L1) of the piston.

[0045] As a result, between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder, it is possible to increase the viscous force of the oil film while suppressing an increase in sliding loss, and it is possible to further suppress leakage of the refrigerant gas. Therefore, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0046] Another hermetic refrigerant compressor according to the present disclosure includes a hermetic container, a refrigerating machine oil stored in the hermetic container and having a kinematic viscosity at 40°C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block accommodated in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber. The ratio L1 / D of the total length (L1) of the piston to the piston diameter (D) is in the range of 0.8 to 1.0, and when the length of the region where the piston seals the compression chamber by its reciprocating motion is defined as the seal length (L2), the ratio L2 / L1 of the seal length (L2) to the total length (L1) of the piston is in the range of 0.9 to 1.0.

[0047] According to the above-described configuration, as the refrigerating machine oil, a kinematic viscosity at 40°C is 1.0 mm 2 / s to 2.5 mm 2When using a low-viscosity oil within the range of / s, the ratios L1 / D and L2 / L1 are set within a predetermined range. As a result, while suppressing an increase in sliding loss, the seal length (L2) can be relatively increased without excessively increasing the overall piston length (L1). Therefore, between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder, the viscous force of the oil film can be increased while suppressing an increase in sliding loss.

[0048] Also, between the piston and the cylinder, the region sealed by the oil film of the refrigeration oil can be relatively increased. Therefore, refrigerant gas leakage can be further suppressed.

[0049] Furthermore, if the seal length (L2) increases, it becomes possible to stabilize the posture of the piston reciprocating in the compression chamber. As a result, it also becomes possible to further suppress an increase in sliding loss.

[0050] Therefore, by setting the ratios L1 / D and L2 / L1 within a predetermined range, when using a low-viscosity oil as the refrigeration oil, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0051] In the hermetic refrigerant compressor having any of the above configurations, the compression element includes, as a shaft portion, a crankshaft having a main shaft and an eccentric shaft, and as a bearing portion for pivotally supporting the shaft portion, a main bearing for pivotally supporting the main shaft and an eccentric bearing for pivotally supporting the eccentric shaft. The sliding surface of the main shaft with the main bearing is divided into a plurality of surfaces. When the total axial length of the plurality of sliding surfaces is defined as the total sliding length Tt, a configuration in which the ratio Tt / K of the total sliding length Tt to the outer diameter K of the main shaft is 1.26 or less may be used.

[0052] According to the above configuration, by applying the configuration for setting the ratio Tt / K and the configuration using a sulfur-based sliding property improver, even when the sliding area is reduced using a low-viscosity lubricating oil, the main shaft sliding portion composed of the main shaft - main bearing can be lubricated well, and wear of the main shaft sliding portion can be suppressed well. As a result, the reliability of the refrigerant compressor can be made even better. Moreover, even when the operating frequency is in the range of 16 r / s or more and 35 r / s or less, that is, when operating at a low rotational speed, good wear resistance can be achieved even if the supply amount of the refrigeration machine oil decreases. Therefore, an increase in sliding loss in the main shaft sliding portion can also be suppressed, and a good coefficient of performance (COP) can be achieved.

[0053] In the hermetic refrigerant compressor having any of the above configurations, the compression element includes, as a shaft portion, a crankshaft having a main shaft and an eccentric shaft, and, as a bearing portion for supporting the shaft portion, a main bearing for supporting the main shaft and an eccentric bearing for supporting the eccentric shaft. The sliding surface of the main shaft with the main bearing is a single surface or is divided into a plurality of surfaces. When the sliding surface is a single surface, when the axial length of the sliding surface is defined as a single sliding length T, or when the sliding surface is divided into a plurality of surfaces, when the axial length of the sliding surface with the minimum axial length is defined as a single sliding length T, the ratio T / K of the single sliding length T to the outer diameter K of the main shaft is 0.51 or less. Further, the refrigeration machine oil may be configured to contain sulfur or a compound containing sulfur as a sliding property improver.

[0054] According to the above configuration, by applying the configuration for setting the ratio T / K and the configuration using a sulfur-based sliding property modifier, even when the sliding area is reduced using a low-viscosity lubricating oil, the main shaft sliding portion composed of the main shaft and the main bearing can be lubricated well, and wear of the main shaft sliding portion can be suppressed well. As a result, the reliability of the refrigerant compressor can be made even better. Moreover, even when the operating frequency is in the range of 16 r / s or more and 35 r / s or less (low rotational speed operation), good wear resistance can be achieved even when the supply amount of the refrigeration oil decreases. Therefore, an increase in sliding loss in the main shaft sliding portion can also be suppressed, so that a good coefficient of performance (COP) can be achieved.

[0055] In the hermetic refrigerant compressor having any of the above configurations, the compression element further includes a crankshaft having a main shaft and an eccentric shaft, a main bearing that supports the main shaft, and a thrust bearing provided on the thrust surface of the main bearing. When the end on the compression chamber side is defined as the first end and the opposite end is defined as the second end on the sliding surface of the main bearing, and the distance between the axis of the compression chamber and the second end of the sliding surface of the main bearing is P, and the distance between the axis of the compression chamber and the first end of the sliding surface of the main bearing is Q, a configuration may be adopted in which when the distance P is within the range of 38 mm to 51 mm, the distance Q is 16 mm or less.

[0056] According to the above configuration, the main shaft load can be reduced only by using a low-viscosity oil as the refrigeration oil, but by setting the distance Q of the refrigerant compressor to 16 mm or less, the main shaft load can be further reduced. Therefore, it is possible to achieve high efficiency and good reliability of the refrigerant compressor not only in the sliding portion between the piston and the cylinder but also in the main shaft sliding portion. As a result, the coefficient of performance (COP) of the refrigerant compressor can be made even better.

[0057] In addition, the present disclosure also includes an operating method for a hermetic refrigerant compressor. That is, the operating method for the hermetic refrigerant compressor according to the present disclosure includes a hermetic container and a refrigeration oil stored in the hermetic container, having a kinematic viscosity at 40 °C of 1.0 mm 2 / s to 2.5 mm 2In a hermetic refrigerant compressor including refrigerant oil within the range of / s, a cylinder block that is housed within the sealed container and forms a compression chamber, and a piston that is reciprocally inserted within the compression chamber, when the operating frequency thereof is 16 r / s or more and 35 r / s or less, it is sufficient for the average speed of reciprocation of the piston to exceed 0.31 m / s.

[0058] Further, the present disclosure also includes a hermetic refrigerant compressor having the above-described configuration, or a refrigeration / air-conditioning apparatus using a hermetic refrigerant compressor that executes the operation method having the above-described configuration. That is, the refrigeration / air-conditioning apparatus according to the present disclosure may have a configuration including the hermetic refrigerant compressor having the above-described configuration (or a hermetic refrigerant compressor that executes the operation method having the above-described configuration), a radiator, a decompression device, and an absorber, and a refrigerant circuit that annularly connects these by piping.

[0059] Hereinafter, exemplary embodiments of the present disclosure will be specifically described with reference to the drawings. However, detailed descriptions of some of the following embodiments may be omitted. For example, detailed descriptions of well-known matters or overlapping descriptions of substantially identical configurations may be omitted. This is to avoid making the following description overly redundant and to facilitate understanding by those skilled in the art.

[0060] Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0061] (Embodiment 1) [Configuration of Hermetic Refrigerant Compressor] First, a typical configuration example of the hermetic refrigerant compressor according to the present disclosure will be specifically described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a hermetic refrigerant compressor 100 (hereinafter, may be abbreviated as refrigerant compressor 100) according to Embodiment 1 of the present disclosure.

[0062] As shown in FIG. 1, the refrigerant compressor 100 is filled with refrigerant gas 181, for example, R600a, as a refrigerant gas inside the sealed container 102, and mineral oil is stored as the refrigeration machine oil 180 at the bottom. Further, a compressor main body 108 is accommodated in the sealed container 102, and the compressor main body 108 is elastically supported by a suspension spring 190. The compressor main body 108 includes an electric element 104 and a compression element 106.

[0063] The electric element 104 is at least composed of a stator 150 and a rotor 152. The compression element 106 has a reciprocating configuration driven by the electric element 104, and includes a crankshaft 120, a cylinder block 130, a piston 140, connecting means 142, and the like. The crankshaft 120 is at least composed of a main shaft 124 with the rotor 152 shrink-fitted thereon and an eccentric shaft 122 formed eccentrically with respect to the main shaft 124. In the present embodiment, the crankshaft 120 is made of, for example, an iron-based material.

[0064] A flange portion 128 is provided between the main shaft 124 and the eccentric shaft 122. As shown by the dashed-dotted line in FIG. 1, the rotation axis of the crankshaft 120 corresponds to the axis of the main shaft 124. The main shaft 124 and the eccentric shaft 122 are fixed via the flange portion 128 so that their axes are displaced from each other. Therefore, the axis of the eccentric shaft 122 is eccentric with respect to the axis of the main shaft 124 (the rotation axis of the crankshaft 120).

[0065] Among the crankshaft 120, the eccentric shaft 122 is located above the refrigerant compressor 100, and the main shaft 124 is located below the refrigerant compressor 100. Therefore, this vertical positional relationship (direction) is also used when explaining the position of the crankshaft 120. For example, the upper end of the eccentric shaft 122 faces the inner upper surface of the sealed container 102, and the lower end of the eccentric shaft 122 is connected to the main shaft 124.

[0066] The upper end of the main shaft 124 is connected to the eccentric shaft 122, the lower end of the main shaft 124 faces the inner lower surface of the sealed container 102, and the lower end of the main shaft 124 is immersed in the refrigeration machine oil 180. Further, an oil supply mechanism 125 is provided on the crankshaft 120, and the oil supply mechanism 125 supplies the refrigeration machine oil 180 from the lower end of the main shaft 124 immersed in the refrigeration machine oil 180 to the upper end of the eccentric shaft 122. As will be described later, the refrigeration machine oil 180 lubricates each sliding part provided in the refrigerant compressor 100 and controls the seal between the compression chamber 133 and the piston 140.

[0067] The outer peripheral surface of the main shaft 124 of the crankshaft 120 includes sliding surfaces 126a, 126b and a non-sliding outer peripheral surface 127. For convenience of explanation, the upper sliding surface 126a of the main shaft 124 is referred to as the first sliding surface 126a, and the lower sliding surface 126b of the main shaft 124 is referred to as the second sliding surface 126b. The non-sliding outer peripheral surface 127 is located between the first sliding surface 126a and the second sliding surface 126b.

[0068] In the present disclosure, the "sliding surface" means an outer peripheral surface or an inner peripheral surface of a plurality of sliding members constituting a sliding part, which is a surface that can be in sliding contact with the other inner peripheral surface or outer peripheral surface. The "non-sliding outer peripheral surface (non-sliding surface)" is, unlike the sliding surface, a surface that does not come into contact with the other inner peripheral surface or outer peripheral surface. In the present embodiment, the non-sliding outer peripheral surface 127 is configured such that the outer diameter of the main shaft 124 is smaller than that of the sliding surfaces 126a, 126b (the outer diameter is made thinner, recessed from the sliding surfaces 126a, 126b, or formed with a central hole).

[0069] The cylinder block 130 includes a cylinder 132 and a main bearing 134. The cylinder 132 forms a compression chamber 133 inside. The main bearing 134 rotatably supports the main shaft 124. In the present embodiment, the cylinder 132 and the main bearing 134 are integrally formed as one cylinder block 130, for example, by cast iron.

[0070] In this embodiment, as shown in FIG. 1, if the extending direction (vertical direction) of the crankshaft 120 is defined as the "longitudinal direction", the cylinder block 130 has a main body that extends in the "lateral direction" (a direction perpendicular to the longitudinal direction) inside the refrigerant compressor 100. The main bearing 134 is formed in a tubular (cylindrical) shape that extends in the "longitudinal direction" (vertical direction) with respect to the main body of the cylinder block 130. The inner peripheral surface of the main bearing 134 is slidably in contact with the outer peripheral surface of the main shaft 124, that is, the sliding surfaces 126a and 126b. Therefore, the inner peripheral surface of the main bearing 134 is a sliding surface.

[0071] Note that the non-sliding outer peripheral surface 127 of the main shaft 124 is located between the upper end and the lower end of the main bearing 134. Therefore, in the state where the main shaft 124 is supported by the main bearing 134, the upper end of the main bearing 134 is in contact with the first sliding surface 126a of the main shaft 124, and the lower end of the main bearing 134 is in contact with the second sliding surface 126b. At this time, the non-sliding outer peripheral surface 127 having a smaller outer diameter than the sliding surfaces 126a and 126b is not in contact with the inner peripheral surface (sliding surface) of the main bearing 134 and is not exposed from the upper end and the lower end of the main bearing 134.

[0072] In this embodiment, the main bearing 134 includes a thrust surface 136 and a tubular extension 137. The thrust surface 136 of the main bearing 134 is a flat surface portion that extends in a direction (a direction perpendicular to the axial center, that is, the extending direction (vertical direction) of the main shaft 124, a vertical direction, a horizontal direction).

[0073] The tubular extension 137 of the main bearing 134 is tubular (cylindrical) and extends further upward from the thrust surface 136. In other words, it is a portion that extends upward from the tubular main bearing 134 body. Therefore, the tubular extension 137 and the main bearing 134 body together have an inner peripheral surface (sliding surface) that faces the outer peripheral surface (sliding surface) of the main shaft 124. A thrust ball bearing 210 is provided on the thrust surface 136 of the main bearing 134.

[0074] The cylinder 132 is provided in the main body of the cylinder block 130, and the inside of the cylinder 132 serves as a compression chamber 133. The compression chamber 133 is a cylindrical (cylindrical) bore that extends "horizontally" inside the refrigerant compressor 100. The piston 140 is reciprocally inserted into this compression chamber 133. Therefore, the compression chamber 133 is closed by the insertion of the piston 140. Also, the direction in which the piston 140 reciprocates is "horizontal".

[0075] The connecting means 142 is made of, for example, an aluminum casting, supports the eccentric shaft 122, and is connected to the piston 140. Therefore, the eccentric shaft 122 and the piston 140 are connected by the connecting means 142.

[0076] The electric element 104 includes a rotor 152 and a stator 150 that is arranged coaxially with the rotor 152 so as to surround the rotor 152. The stator 150 is arranged on the outer diameter side of the rotor 152 so as to maintain a substantially constant gap with the rotor 152, and is fixed to the leg portion of the cylinder block 130. Also, the rotor 152 is fixed to the main shaft 124 of the crankshaft 120.

[0077] Therefore, in the refrigerant compressor 100, when the rotor 152 rotates by the electric element 104, the crankshaft 120 rotates. In the crankshaft 120, as described above, the axis of the eccentric shaft 122 is offset with respect to the axis of the main shaft 124, and the eccentric shaft 122 is connected to the piston 140 by the connecting means 142. The piston 140 is reciprocally inserted into the compression chamber 133 in the cylinder 132. Therefore, when the crankshaft 120 rotates, the piston 140 reciprocates in the compression chamber 133 due to the rotation of the eccentric shaft 122.

[0078] Also, as the crankshaft 120 rotates, as described above, the refrigerating machine oil 180 is supplied from the oil supply mechanism 125 to each sliding portion. Thereby, each sliding portion is lubricated by the refrigerating machine oil 180.

[0079] In the present embodiment, as the sliding portion, the main shaft 124 and the main bearing 134 of the crankshaft 120, the piston 140 and the compression chamber 133 (cylinder 132), the connecting portion of the connecting means 142 and the piston 140, the eccentric shaft 122 of the crankshaft 120 and the connecting portion of the connecting means 142, etc. are provided. Note that each member constituting these sliding portions is a sliding member.

[0080] Among these sliding portions, the sliding portion constituted by the piston 140 and the compression chamber 133 (cylinder 132) is referred to as the "cylinder sliding portion" for convenience of explanation. Also, the sliding portion constituted by the main shaft 124 of the crankshaft 120 and the main bearing 134 is referred to as the "main shaft sliding portion" for convenience of explanation.

[0081] Note that the specific configuration of the refrigerant compressor 100 according to the present disclosure is not limited to the configuration shown in FIG. 1 described above. The refrigerant compressor 100 according to the present disclosure includes an electric element 104 and a compression element 106, and the compression element 106 may have a configuration including a cylinder block 130 having a compression chamber 133 and a piston 140 reciprocally inserted inside the compression chamber 133.

[0082] For example, in the refrigerant compressor 100 shown in FIG. 1, inside the sealed container 102, the electric element 104 is located on the lower side and the compression element 106 is located on the upper side. However, the electric element 104 may be located on the upper side and the compression element 106 may be located on the lower side.

[0083] Alternatively, in the refrigerant compressor 100 shown in FIG. 1, the electric element 104 is of an inner rotor type, and the rotor 152 is coaxially arranged with the stator 150 and rotatably disposed inside the inner peripheral portion of the stator 150. However, the configuration of the electric element 104 is not limited to this, and an outer rotor type, that is, a configuration in which the rotor 152 is coaxially arranged with the stator 150 and rotatably disposed on the outer periphery of the stator 150 may also be acceptable.

[0084] Alternatively, in the refrigerant compressor 100 shown in FIG. 1, the main shaft 124 of the crankshaft 120 has a first sliding surface 126a, a non-sliding outer peripheral surface 127, and a second sliding surface 126b. However, the configuration of the main shaft 124 is not limited to this. As in the second embodiment described later, the sliding surface 126 of the main shaft 124 may constitute the entire outer peripheral surface of the main shaft 124, or may include three or more sliding surfaces 126.

[0085] The specific configuration of the refrigeration machine oil 180 used in the present disclosure is not particularly limited. In the present disclosure, as the refrigeration machine oil 180, an oil (low-viscosity oil) having a kinematic viscosity at 40 ° C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s (1.0 mm 2 / s or more and 2.5 mm 2 / s or less) may be used. The specific configuration of the low-viscosity oil is not particularly limited. In the first embodiment, for example, a low-viscosity mineral oil is used. However, as described in the fourth embodiment described later, another oily substance may be used instead of the mineral oil, or another oily substance may be used in combination with the mineral oil, or various additives may be added.

[0086] Note that if the kinematic viscosity at 40 ° C of the refrigeration machine oil 180 (low-viscosity oil) in the present disclosure exceeds 2.5 mm 2 / s, from the viewpoint of realizing a good coefficient of performance (COP), the viscous resistance becomes too large. If the viscous resistance increases, the input power to the refrigerant compressor 100 increases, so that a better coefficient of performance (COP) cannot be realized.

[0087] On the other hand, when the kinematic viscosity at 40 ° C of the refrigeration machine oil 180 is less than 1.0 mm 2 / s, the oil film formed on each sliding part becomes too thin inside the refrigerant compressor 100. If the oil film becomes thin in the sliding part, the possibility of breakage increases, and a good lubricating action cannot be obtained in the sliding part. As a result, the metal contact between the sliding surfaces increases in the sliding part, and the reliability of the sliding part may decrease.

[0088] Here, the kinematic viscosity of the refrigeration oil 180 according to the present disclosure at 40°C only needs to be within the above range, but the upper limit value or the lower limit value can be appropriately changed within the above range according to various conditions. For example, the upper limit value of the kinematic viscosity of the refrigeration oil 180 at 40°C can be 2.4 mm 2 / s. Also, the lower limit value of the kinematic viscosity of the refrigeration oil 180 at 40°C can be 1.5 mm 2 / s.

[0089] Note that these upper limit values or lower limit values may be values including (less than or equal to or greater than or equal to) the numerical values, or may be values not including (less than or exceeding) the numerical values. For example, the upper limit value may be less than 2.5 mm 2 / s, or may be less than or equal to 2.4 mm 2 / s, or may be less than 2.4 mm 2 / . The same applies to the lower limit value. Depending on various conditions, by setting the kinematic viscosity of the refrigeration oil 180 at 40°C to less than or equal to 2.4 mm 2 / s or less, or greater than or equal to 1.5 mm 2 / s or more, it becomes easier to realize a more suitable viscous resistance or a more suitable oil film thickness from the viewpoint of realizing a better coefficient of performance (COP).

[0090] [Operating Method of Refrigerant Compressor and Piston Configuration] Next, the operating method of the hermetic refrigerant compressor according to the present disclosure and the piston configuration in the hermetic refrigerant compressor will be described with reference to the above-described refrigerant compressor 100 shown in FIG. 1. Here, the "piston configuration" referred to herein includes not only the specific configuration of the piston 140 itself, but also conditions set when the piston 140 reciprocates in the compression chamber 133, etc.

[0091] In the refrigerant compressor 100, first, power is supplied from a commercial power source to the electric element 104, causing the rotor 152 of the electric element 104 to rotate. Due to the rotation of the rotor 152, the crankshaft 120 rotates as described above. Therefore, the eccentric motion of the eccentric shaft 122 with respect to the main shaft 124 is transmitted to the piston 140 via the connecting means 142. As a result, the eccentric motion of the eccentric shaft 122 is converted into a reciprocating motion of the piston 140, and the piston 140 is driven to reciprocate inside the cylinder 132, that is, inside the compression chamber 133. The refrigerant gas 181 introduced into the sealed container 102 is sucked into the compression chamber 133 and compressed by the reciprocating motion of the piston 140.

[0092] Here, in the present disclosure, it is desirable that the refrigerant compressor 100 be inverter-driven at a plurality of operating frequencies. That is, the refrigerant compressor 100 according to the present disclosure may include at least an inverter circuit that controls the operating frequency as a controller for controlling the operation of the refrigerant compressor 100. The specific configuration of the inverter circuit is not particularly limited as long as it can rotationally drive the electric element 104 at a plurality of operating rotational speeds. The inverter circuit may be chip-sized or may be a microprocessor or the like that operates according to a program that executes rotational driving at a plurality of operating rotational speeds.

[0093] In the present disclosure, the operating frequency of the refrigerant compressor 100 is not particularly limited. Generally, if the operating frequency of the refrigerant compressor 100 is decreased, its power consumption can be suppressed. However, in a refrigeration cycle (refrigeration and refrigeration equipment) including the refrigerant compressor 100, the operating frequency can also increase according to the peak of its refrigerating capacity. Therefore, the operating frequency of the refrigerant compressor 100 is not always in a low range.

[0094] Here, in the present disclosure, as the refrigerating machine oil 180 stored in the sealed container 102 of the refrigerant compressor 100, low-viscosity oil (low-viscosity lubricating oil) having a kinematic viscosity at 40 °C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s is used.

[0095] When a low-viscosity oil is used as the refrigeration oil 180, although the sliding loss can be reduced well, the lubricating action in the sliding part tends to decrease. Therefore, when the refrigeration oil 180 is a low-viscosity oil, as a method of avoiding or suppressing the decrease in the lubricating action, for example, a measure such as performing a surface treatment on the sliding surface constituting the sliding part is generally selected.

[0096] Furthermore, as described above, according to the study by the inventors of the present invention, when the kinematic viscosity at 40 ° C in the refrigeration oil 180 is 2.5 mm 2 / s or less, it has also been clarified that the leakage amount of the refrigerant gas 181 from between the piston 140 and the cylinder 132 (between the outer peripheral surface of the piston 140 and the inner peripheral surface of the cylinder 132 (inner peripheral surface of the compression chamber 133)) becomes too large (see also the examples described later). As a method of suppressing the leakage amount of the refrigerant gas 181, for example, a measure such as reducing the clearance between the surface of the piston 140 and the inner surface of the compression chamber 133 is generally selected.

[0097] On the other hand, in the present disclosure, as the refrigeration oil 180 stored in the sealed container 102, when a low-viscosity oil having a kinematic viscosity at 40 ° C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s is used, when the operating frequency is controlled to be 16 r / s or more and 35 r / s or less by an inverter circuit (or a controller), the refrigerant compressor 100 is operated so that the average speed of the reciprocating motion of the piston 140 (piston average speed) exceeds 0.31 m / s.

[0098] By using such an operation method, even when a low-viscosity oil having a kinematic viscosity at 40 ° C of 2.5 mm 2 / s or less is used as the refrigeration oil 180, in the "cylinder sliding part", that is, in the sliding part constituted by the piston 140 and the compression chamber 133 in the cylinder 132, an oil film of the refrigeration oil 180 can exhibit good viscous force (viscous resistance) between the piston 140 and the cylinder 132. As a result, good sliding performance can be realized in the cylinder sliding part and the leakage of the refrigerant gas 181 can also be effectively suppressed.

[0099] Therefore, when the refrigerant compressor 100 is operated within a range of low operating frequencies, that is, when the operating frequency is controlled within the range of 16 r / s to 35 r / s, it is possible to suppress or avoid an increase in the power consumption of the refrigerant compressor 100, and it is possible to achieve a good coefficient of performance (COP) in the refrigerant compressor 100.

[0100] On the other hand, in the cylinder sliding portion, if the oil film of the refrigerating machine oil 180 cannot exhibit a good viscous force, it becomes difficult to maintain a good oil film between the piston 140 and the cylinder 132 against the pressure of the refrigerant gas 181 in the compression chamber 133. As a result, the oil film is likely to break between the piston 140 and the cylinder 132, and as a result, a significant amount of the refrigerant gas 181 leaks.

[0101] The viscous force of the oil film of the refrigerating machine oil 180 in the cylinder sliding portion will be specifically described with reference to FIG. 2. FIG. 2 is a schematic side view (schematic partial cross-sectional view) in which a main part of the configuration of the cylinder sliding portion provided in the refrigerant compressor 100 shown in FIG. 1 is enlarged.

[0102] In FIG. 2, a part of the cylinder 132 provided in the cylinder block 130, a part of the compression chamber 133 formed in the cylinder 132, and a part of the piston 140 slidably inserted into the compression chamber 133 are schematically illustrated. The compression chamber 133 is filled with the refrigerant gas 181, and an oil film made of the refrigerating machine oil 180 is formed between the outer peripheral surface of the piston 140 and the inner peripheral surface of the cylinder 132 (inner peripheral surface of the compression chamber 133).

[0103] When the viscous force (F1) of the oil film of the refrigerating machine oil 180 intervening between the piston 140 and the cylinder 132 is considered, the viscous force (F1) can be expressed by the following formula (1) depending on the viscosity (η) of the refrigerating machine oil 180, the seal length (L2) of the piston 140, the clearance (σ) between the piston 140 and the cylinder 132, and the average piston speed (V). F1 = (η × L2 × V) / σ ···(1)

[0104] Note that the seal length (L2) is the length of the region where the piston 140 seals the inside of the compression chamber 133 due to its reciprocating motion. Also, the viscous force (F1) of the oil film is a force that acts from the outside to the inside with respect to the compression chamber 133, as schematically shown by the block arrow in FIG. 2. Further, the clearance (σ) between the piston 140 and the cylinder 132 is schematically shown in FIG. 2, and ideally, the oil film of the refrigerating machine oil 180 fills the clearance (σ) without breakage.

[0105] If the viscous force (F1) of the oil film becomes small, it becomes difficult for the refrigerating machine oil 180 to maintain the state of the oil film between the piston 140 and the cylinder 132 against the pressure of the refrigerant gas 181 filling the inside of the compression chamber 133. As a result, the oil film is likely to break between the piston 140 and the cylinder 132, and as a result, a significant amount of the refrigerant gas 181 is likely to leak.

[0106] Therefore, in order to increase the viscous force (F1) of the oil film, it is possible to increase the piston average speed (V) (increase the speed), increase the seal length (L2) of the piston 140, or decrease the clearance (σ) between the piston 140 and the cylinder 132.

[0107] In the present disclosure, when the refrigerating machine oil 180 is a low-viscosity oil, the piston average speed (V) is set to be large in order to exhibit a good viscous force of the oil film between the piston 140 and the cylinder 132. In the cylinder sliding portion, since the piston 140 reciprocates, the speed at which the piston 140 actually moves in the compression chamber 133 is not constant. Therefore, in the present disclosure, the piston average speed is used. The piston average speed (V) can be defined as the product of the stroke amount (S) of the piston 140 and the operating frequency (Fr) (V = S × Fr).

[0108] In the present disclosure, the operating frequency (operating rotational speed) of the refrigerant compressor 100 is not particularly limited. Typically, the lower limit of the operating frequency can be 13 r / s (rps), and this lower limit may be 16 r / s. On the other hand, the upper limit of the operating frequency can be 80 r / s, and this upper limit may be 75 r / s.

[0109] Therefore, as an example of a typical range of operating frequencies, a range within 13 to 80 r / s can be cited, and it may also be within the range of 16 to 75 r / s. Of course, it may be within the range of 16 to 80 r / s, or it may be within the range of 13 r / s to 75 r / s. Note that although the input power to the refrigerant compressor 100 increases, the upper limit of the operating frequency may exceed 80 r / s.

[0110] Also, from the perspective of reducing the input power to the refrigerant compressor 100, the operating frequency may be made lower than 13 r / s. However, if the operating frequency is made too low, there is a possibility that sufficient reliability cannot be obtained for both the coefficient of performance (COP) of the refrigerant compressor 100 and the wear of the cylinder sliding part. Therefore, the preferable lower limit of the operating frequency can be 16 r / s.

[0111] In the present disclosure, within such a range of operating frequencies, in particular, the range of 16 r / s or more and 35 r / s or less is defined as the "low-speed operating frequency". In the refrigerant compressor 100 according to the present disclosure, when it is within this range of low-speed operating frequencies, the piston average speed is increased so as to exceed 0.31 m / s. Therefore, the lower limit of the piston average speed in the present disclosure only needs to exceed 0.31 m / s.

[0112] When the piston average speed is 0.31 m / s or less, the oil film of the low-viscosity oil (refrigerant oil 180) between the piston 140 and the cylinder 132 cannot exert sufficient viscous force. As a result, when the refrigerant compressor 100 is operating within the range of low-speed operating frequencies, the refrigerant gas 181 is likely to leak from between the piston 140 and the cylinder 132.

[0113] Note that the lower limit of the piston average speed only needs to exceed 0.31 m / s as described above. Depending on various conditions, it may be 0.32 m / s or more, or may be 0.34 m / s or more. If the lower limit of the piston average speed is 0.32 m / s or more, although it also depends on various conditions, the oil film of the refrigeration oil 180 between the piston 140 and the cylinder 132 is more likely to exhibit better viscous force. Thereby, it becomes possible to better suppress the leakage of the refrigerant gas 181 from between the piston 140 and the cylinder 132.

[0114] In the present disclosure, based on the above formula (1), a configuration can be adopted in which the ratio S / D of the reciprocating stroke amount (S) of the piston 140 to the piston diameter (D) is set within the range of 0.78 to 1.00 (0.78 ≤ S / D ≤ 1.00). The reciprocating stroke amount (S) of the piston 140 is determined by twice the eccentricity radius of the eccentric shaft 122. Since this ratio S / D corresponds to the conditions set when the piston 140 reciprocates in the compression chamber 133, it can be said to be the piston configuration described above.

[0115] In this way, by setting the ratio S / D of the stroke amount (S) to the piston diameter (D) within the above range, the stroke amount of the piston 140 can be made relatively long (large), so that the piston average speed (V) can be increased. If the piston average speed (V) increases, as described above, the viscous force (F1) of the oil film can be increased only by that much, and it becomes easier to form an oil film between the piston 140 and the cylinder 132. Thereby, it becomes possible to suppress the leakage of the refrigerant gas 181.

[0116] Furthermore, when the ratio S / D is within the above range and the stroke amount (S) increases, it means that the piston diameter (D) becomes relatively smaller. By reducing the piston diameter (D), the total area of the clearance (σ) between the piston 140 and the cylinder 132 can be reduced. Reducing the total area of the clearance means that the "opening area" where the refrigerant gas 181 may leak out becomes narrower. Therefore, it is possible to suppress the leakage of the refrigerant gas 181 from between the piston 140 and the cylinder 132.

[0117] Furthermore, if the piston diameter (D) is reduced, the compression load of the refrigerant gas 181 by the piston 140 can be reduced. That is, when the piston 140 reciprocates in the compression chamber 133, the load applied to the tip surface of the piston 140 from the refrigerant gas 181 in the compression chamber 133 becomes relatively smaller. Thereby, the input power for reciprocating the piston 140 can be reduced. Therefore, the coefficient of performance (COP) of the refrigerant compressor 100 can be improved.

[0118] In the field of refrigerant compressors 100 heretofore, as disclosed in "Hermetic Refrigerators" written by Mutsuyoshi Kawahira, published by the Japan Refrigeration Association in July 1981, the ratio S / D of the stroke amount (S) to the piston diameter (D) has been desirably in the range of 0.4 to 0.8. In contrast, in the present disclosure, the ratio S / D is set within the range of 0.78 to 1.00. Therefore, the ratio S / D in the present disclosure is set to be substantially larger than the conventional range. In particular, in the present disclosure, the lower limit of the ratio S / D may be 0.81 or more (0.81 ≦ S / D), or 0.84 or more (0.84 ≦ S / D).

[0119] If the ratio S / D is less than 0.78, a low-viscosity oil (kinematic viscosity at 40°C is 1.0 mm 2 / s to 2.5 mm 2When used within the range of / s, the stroke amount (S) of the piston 140 may not be able to be relatively increased, and the piston diameter (D) may not be able to be relatively decreased. If the lower limit of the ratio S / D is 0.81 or more, the effect of being able to relatively increase the stroke amount (S) and relatively decrease the piston diameter (D) can be made more certain. If the lower limit of the ratio S / D is 0.84 or more, the above-mentioned effect can be made even more certain.

[0120] On the other hand, when the ratio S / D exceeds 1.00, the stroke amount (S) of the piston 140 becomes relatively too large, and the sliding loss between the piston 140 and the cylinder 132 becomes relatively large. As a result, the effect of achieving a good coefficient of performance (COP) in the refrigerant compressor 100 cannot be obtained.

[0121] Note that the specific stroke amount (S) of the piston 140 is not particularly limited, but in this embodiment, for example, 19.5 mm or more can be cited as the lower limit of the stroke amount (S). The lower limit of the stroke amount (S) may also be 20 mm or more. On the other hand, the upper limit of the stroke amount (S) is not particularly limited either, but if the stroke amount (S) becomes excessively large, there is a risk that the sliding loss between the piston 140 and the cylinder 132 will become relatively large. From this perspective, 30 mm or less can be cited as the upper limit of the stroke amount (S).

[0122] Also, the specific interval of the clearance (σ) between the piston 140 and the cylinder 132 is not particularly limited, but in this embodiment, for example, 3 μm can be cited as the lower limit of the clearance (σ), and 10 μm can be cited as the upper limit of the clearance (σ). When the clearance (σ) exceeds 10 μm, particularly when a low-viscosity oil is used as the refrigeration machine oil 180, the viscous force (F1) becomes small (see the above formula (1)).

[0123] On the other hand, if the clearance (σ) is less than 3 μm, especially when using low-viscosity oil as the refrigerant oil 180, the reciprocating piston 140 may easily contact the inner peripheral surface of the cylinder 132 (compression chamber 133).

[0124] In the present disclosure, based on the above formula (1), the ratio L1 / D of the total piston length (L1) to the piston diameter (D) in the piston 140 is in the range of 0.8 to 1.0 (0.8 ≦ L1 / D ≦ 1.0), and the ratio L2 / L1 of the seal length (L2) to the total piston length (L1) is in the range of 0.9 to 1.0 (0.9 ≦ L2 / L1 ≦ 1.0). A configuration can be adopted.

[0125] Among these ratios, the ratio L1 / D corresponds to the specific configuration (conditions) of the piston 140, and the ratio L2 / L1 corresponds to the conditions set when the piston 140 reciprocates in the compression chamber 133. Therefore, both of these ratios can be referred to as the piston configuration described above.

[0126] Regarding the relationship between the piston diameter (D), the total piston length (L1), and the seal length (L2) in the piston 140, which is defined by the ratios L1 / D and L2 / L1, it will be specifically described with reference to FIGS. 3A and 3B. FIG. 3A is a schematic side view showing a typical example of the piston 140 used in the refrigerant compressor 100 shown in FIG. 1, and FIG. 3B is a schematic side view showing a typical example of a conventional piston.

[0127] As shown in FIG. 3A, in the piston 140 used in the refrigerant compressor 100 according to the present embodiment, the total piston length (L1), that is, the length along the direction in which the piston 140 reciprocates, is of the same order as the piston diameter (D), that is, the diameter of the piston 140. Further, in the piston 140, the total piston length (L1) is also of the same order as the seal length (L2), that is, the length of the region that seals the inside of the compression chamber 133 by the reciprocation of the piston 140 described above.

[0128] On the other hand, as shown in FIG. 3B, in the conventional piston 240, the overall piston length (L1) is larger than the piston diameter (D), and the overall piston length (L1) is larger than the seal length (L2).

[0129] As is clear from the above formula (1), increasing the seal length (L2) can increase the viscous force (F1) of the oil film of the refrigeration oil 180. Also, if the seal length (L2) is large, it means that the area sealed by the oil film in the cylinder sliding part becomes large. Therefore, if the seal length (L2) is relatively large, it is possible to better suppress the leakage of the refrigerant gas 181.

[0130] In order to ensure a sufficient seal length (L2), the overall piston length (L1) also needs to be of sufficient size. On the other hand, if the overall piston length (L1) is too large, the sliding loss in the cylinder sliding part increases. In particular, when the refrigeration oil 180 is a low-viscosity oil (kinematic viscosity at 40 °C is 2.5 mm 2 / s or less), it becomes difficult to form a good oil film in the cylinder sliding part compared to higher-viscosity oils.

[0131] Therefore, as a result of intensive studies on the criteria for setting an appropriate overall piston length (L1), it has become clear that when the refrigeration oil 180 is a low-viscosity oil, it is sufficient to use the piston diameter (D) as a reference.

[0132] If the ratio L1 / D is within the range of 0.8 to 1.0 as in the piston 140 shown in FIG. 3A, a suitable range of the overall piston length (L1) corresponding to the low-viscosity oil is defined in the cylinder sliding part. Thereby, it is possible to realize an overall piston length (L1) that can ensure a good seal length (L2) while suppressing an increase in sliding loss.

[0133] If the ratio L1 / D is less than 0.8, when using a low-viscosity oil as the refrigerant oil 180, the total length of the piston (L1) becomes relatively short. As a result, it becomes impossible to ensure a sufficient sealing length (L2), so that not only the size of the region sealed by the oil film itself becomes insufficient, but also the viscous force (F1) of the oil film based on the above formula (1) cannot be increased.

[0134] On the other hand, for example, like the conventional piston 240 shown in FIG. 3B, if the ratio L1 / D exceeds 1.0, when using a low-viscosity oil as the refrigerant oil 180, the total length of the piston (L1) becomes too large. As a result, there is a risk of increasing the sliding loss in the cylinder sliding portion. If the sliding loss increases, it becomes difficult to achieve a good coefficient of performance (COP).

[0135] Here, in the present disclosure, since a low-viscosity oil is used as the refrigerant oil 180, it is desirable that the sealing length (L2) be as large as possible. For that purpose, it is desirable to increase the total length of the piston (L1) as described above. However, as described above, if the total length of the piston (L1) is too large, the sliding loss in the cylinder sliding portion increases.

[0136] Therefore, in the present disclosure, the ratio L2 / L1 is set within the range of 0.9 to 1.0. As a result, like the piston 140 shown in FIG. 3A, for example, the sealing length (L2) can be relatively increased without excessively increasing the total length of the piston (L1). As a result, as is clear from the above formula (1), it is possible to increase the viscous force (F1) of the oil film while suppressing an increase in the sliding loss in the cylinder sliding portion.

[0137] Moreover, when the seal length (L2) is relatively large with respect to the total piston length (L1), the area sealed by the oil film of the refrigerant oil 180 also becomes relatively large. Therefore, the leakage of the refrigerant gas 181 can be further suppressed. Furthermore, if the seal length (L2) increases, it becomes possible to stabilize the posture of the piston 140 reciprocating in the compression chamber 133. As a result, it also becomes possible to further suppress an increase in sliding loss.

[0138] On the other hand, for example, like the conventional piston 240 shown in FIG. 3B, if the ratio L2 / L1 is less than 0.9, when a low-viscosity oil is used as the refrigerant oil 180, it becomes impossible to sufficiently secure the seal length (L2). Therefore, not only can the viscous force (F1) of the oil film not be increased, but the area sealed by the oil film also becomes relatively small. Therefore, there is a possibility that the leakage of the refrigerant gas 181 cannot be sufficiently suppressed. Also, the ratio L2 / L1 does not exceed 1.0 (because the seal length (L2) is less than or equal to the total piston length (L1)).

[0139] In the present disclosure, the outer peripheral surface of the piston 140 may be a smooth surface without intentionally formed irregularities. For example, an annular oil supply groove may be formed. By forming an oil supply groove on the outer peripheral surface of the piston 140, it becomes possible to supply a sufficient amount of the refrigerant oil 180 to the seal area of the piston 140, particularly when a low-viscosity oil is used as the refrigerant oil 180.

[0140] The specific configuration of the annular oil supply groove is not particularly limited. For example, the number of oil supply grooves is not particularly limited, but typically, one can be cited. Of course, two or more oil supply grooves may be formed. Also, the width of the oil supply groove is not particularly limited, but for example, it can be in the range of 0.1 to 0.5 mm.

[0141] If the width of the oil supply groove is less than 0.1 mm, even if the refrigerant oil 180 is a low-viscosity oil, it becomes difficult to supply sufficient refrigerant oil 180 to the seal area. On the other hand, if the width of the oil supply groove exceeds 0.5 mm, when the refrigerant oil 180 is a low-viscosity oil, the width of the oil supply groove is too wide and the refrigerant oil 180 flows out from the seal area, making it difficult to hold a suitable amount of refrigerant oil 180 in the seal area.

[0142] Here, for convenience of explanation, when the rotational frequency described above is controlled to be 16 r / s or more and 35 r / s or less, the configuration of setting the average speed of the reciprocating motion of the piston 140 (piston average speed) to exceed 0.31 m / s is abbreviated as the "high-speed configuration of the piston average speed (V)", and the configuration of setting the ratio S / D of the stroke amount (S) of the reciprocating motion of the piston 140 to the piston diameter (D) within the range of 0.78 to 1.00 is abbreviated as the "configuration of setting the ratio S / D", and while setting the ratio L1 / D of the total piston length (L1) to the piston diameter (D) of the piston 140 within the range of 0.8 to 1.0 and setting the ratio L2 / L1 of the seal length (L2) to the total piston length (L1) within the range of 0.9 to 1.0, when abbreviated as the "configuration of setting the ratio L1 / D and the ratio L2 / L1", the high-speed configuration of the piston average speed (V), the configuration of setting the ratio S / D, and the configuration of setting the ratio L1 / D and the ratio L2 / L1 can be independently applied to the refrigerant compressor 100.

[0143] That is, in the refrigerant compressor 100 according to the present disclosure, by applying at least any one of the high-speed configuration of the piston average speed (V), the configuration of setting the ratio S / D, and the configuration of setting the ratio L1 / D and the ratio L2 / L1, even when a low-viscosity oil is used as the refrigerant oil 180, leakage of the refrigerant gas 181 can be well suppressed, and a further better coefficient of performance (COP) can be realized.

[0144] Thus, in the hermetic refrigerant compressor according to Embodiment 1, as the refrigerant oil 180, the kinematic viscosity at 40°C is 1.0 mm 2 / s to 2.5 mm 2When using a low-viscosity oil within the range of / s, for example, if it is equipped with a controller that controls the operating frequency of the refrigerant compressor 100, when the operating frequency is controlled by the controller to be 16 r / s or more and 35 r / s or less, it may have a configuration in which the average speed of the reciprocating motion of the piston 140 is set to exceed 0.31 m / s.

[0145] Alternatively, in the hermetic refrigerant compressor according to Embodiment 1, when using the above-mentioned low-viscosity oil as the refrigeration oil, it may have a configuration in which the ratio S / D of the stroke amount (S) of the reciprocating motion of the piston 140 to the piston diameter (D) is within the range of 0.78 to 1.00.

[0146] Alternatively, in the hermetic refrigerant compressor according to Embodiment 1, when using the above-mentioned low-viscosity oil as the refrigeration oil 180, when the length of the region where the piston 140 seals the inside of the compression chamber 133 by its reciprocating motion is defined as the seal length (L2), the ratio L1 / D of the total length (L1) of the piston to the piston diameter (D) is within the range of 0.8 to 1.0, and the ratio L2 / L1 of the seal length (L2) to the total length (L1) of the piston is within the range of 0.9 to 1.0, such a configuration may also be acceptable.

[0147] For a hermetic refrigerant compressor having these configurations, when using a low-viscosity oil as the refrigeration oil 180, it becomes possible to further suppress the leakage of the refrigerant gas 181 from between the piston 140 and the compression chamber 133. Therefore, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0148] (Embodiment 2) The hermetic refrigerant compressor according to Embodiment 2 has a basic configuration similar to that of the hermetic refrigerant compressor according to Embodiment 1, but has a more characteristic configuration regarding the main shaft sliding portion (the sliding portion composed of the main shaft 124 of the crankshaft 120 and the main bearing 134). Since the basic configuration of the hermetic refrigerant compressor according to Embodiment 2 is the same as the configuration shown in FIG. 1 in Embodiment 1, a detailed description thereof is omitted.

[0149] [Main shaft sliding part] Regarding an example of the specific configuration of the main shaft sliding part in the second embodiment, it will be specifically described with reference to FIGS. 4A to 4C. FIG. 4A is a schematic diagram showing an example of the configuration when the sliding surface in the crankshaft 120 provided in the refrigerant compressor 100 shown in FIG. 1 is a single surface, and FIGS. 4B and 4C are schematic diagrams showing an example of the configuration when the sliding surface in the crankshaft 120 is divided into a plurality of surfaces.

[0150] In the hermetic refrigerant compressor shown in FIG. 1, since the main shaft 124 of the crankshaft 120 which is a shaft part has a configuration having a first sliding surface 126a and a second sliding surface 126b, it can be said that the sliding surface of the main shaft 124 is divided into a plurality of surfaces. The configuration of the main shaft 124 shown in FIG. 1, that is, the configuration in which the sliding surface is divided into two surfaces, corresponds to the schematic diagram shown in FIG. 4B. The shaft part according to the present disclosure is not limited to this, and it may be a single surface. For example, as shown in FIG. 4A, the outer peripheral surface of the main shaft 124 may not be divided into a plurality of sliding surfaces and may have only a single sliding surface 126.

[0151] The specific configuration for dividing the sliding surface into a plurality is not particularly limited, but typically, a concave portion (a recessed portion) recessed (depressed) toward the central axis side rather than the sliding surface may be formed between the plurality of sliding surfaces. This concave portion constitutes the non-sliding outer peripheral surface 127 as shown in FIGS. 1 and 4B. The specific shape of the concave portion is also not particularly limited. For example, its depth may be any depth as long as it does not affect the rigidity, strength, etc. of the main shaft 124. Similarly, the width of the concave portion (that is, the interval between the plurality of sliding surfaces) is also not particularly limited and can be appropriately set according to the degree of narrowing (decreasing or reducing) the width (sliding area) of the sliding surface.

[0152] When dividing the sliding surface into a plurality of parts, the specific number of sliding surfaces is not particularly limited. As shown in FIGS. 1 and 4B, it may be divided into a total of two surfaces, i.e., the first sliding surface 126a and the second sliding surface 126b. Alternatively, as shown in FIG. 4C, it may be divided into a total of three surfaces, i.e., the first sliding surface 126c, the second sliding surface 126d, and the third sliding surface 126e, or it may be divided into four or more surfaces. In the configuration shown in FIG. 4C, a first non-sliding outer peripheral surface 127a, which is a recess similar to the non-sliding outer peripheral surface 127, is located between the first sliding surface 126c and the second sliding surface 126d, and a second non-sliding outer peripheral surface 127b is located between the second sliding surface 126d and the third sliding surface 126e.

[0153] Here, in the second embodiment, in the main shaft sliding portion, by setting the ratio of the axial length of the sliding surface to the outer diameter (diameter) of the portion that becomes the sliding surface to a predetermined value or less, the sliding area can be reduced without substantially affecting the wear resistance.

[0154] Specifically, when the sliding surface is a single surface (see FIG. 4A for example), the axial length of the sliding surface is defined as a single sliding length T. When the sliding surface is divided into a plurality of surfaces (see FIGS. 4B or 4C for example), the axial length of the sliding surface with the minimum axial length is defined as the single sliding length T. Then, when the outer diameter (diameter) of the portion that becomes the sliding surface in the shaft portion is defined as an outer diameter K, the shaft portion is designed such that the ratio T / K of the single sliding length T to the outer diameter K of the shaft portion is 0.51 or less.

[0155] In FIG. 4A, for the sake of explaining the outer diameter K and the single sliding length T, the length T (single sliding length T) of the single sliding surface 126 with respect to the outer diameter K is shown enlarged. If it is as shown in FIG. 4A, the ratio T / K exceeds 0.51. However, actually, for example, by forming a recess (non-sliding outer peripheral surface) in the upper part (eccentric shaft 122 side) or the lower part (refrigerating machine oil 180 side) of the main shaft 124 as seen from the single sliding surface 126, the ratio T / K can be set to 0.51 or less (T / K ≦ 0.51).

[0156] In FIG. 4B, the sliding surface is divided into a first sliding surface 126a and a second sliding surface 126b. In the example shown in FIG. 4B, the axial length Ta of the upper first sliding surface 126a is smaller than the axial length Tb of the lower second sliding surface 126b (Ta < Tb). In this case, since the first sliding surface 126a becomes the "sliding surface with the minimum length", the length Ta corresponds to the single sliding length T (T = Ta). In this example, it is sufficient that Ta / K is 0.51 or less on the first sliding surface 126a.

[0157] Note that also in FIG. 4B, similar to FIG. 4A, for the sake of convenience of explanation of the outer diameter K and the length Ta of the first sliding surface 126a, the length Ta is shown enlarged with respect to the outer diameter K. Also in this case, by increasing the axial length of the non-sliding outer peripheral surface 127 or providing a non-sliding outer peripheral surface (recess) not shown above the first sliding surface 126a, the ratio T / K can be set to 0.51 or less.

[0158] In FIG. 4C, the sliding surface is divided into a first sliding surface 126c, a second sliding surface 126d, and a third sliding surface 126e. In the example shown in FIG. 4C, the length Td of the second sliding surface 126d in the central part is smaller than the axial length Tc of the upper first sliding surface 126c, and the length Tc is smaller than the length Te of the lower third sliding surface 126e (Td < Tc < Te). In this case, since the second sliding surface 126d becomes the "sliding surface with the minimum length", the length Td corresponds to the single sliding length T (T = Te). In this example, it is sufficient that Te / K is 0.51 or less on the second sliding surface 126d.

[0159] In the present disclosure, the lower limit value of the ratio T / K is not particularly limited, but as an example of a preferable lower limit value, 0.15 or more can be mentioned. Therefore, as a preferable range of the ratio T / K in the present disclosure, the range of 0.15 to 0.51 can be mentioned. Further, as a more preferable lower limit of the ratio T / K, 0.30 can be mentioned, and as an even more preferable lower limit, 0.42 can be mentioned.

[0160] When the ratio T / K exceeds 0.51, as the refrigeration machine oil 180, a low-viscosity oil (kinematic viscosity at 40°C is 1.0 mm2 / s ~ 2.5 mm 2 When used within the range of / s), even if a sulfur-based sliding property improver described later is added to the refrigeration machine oil 180, sufficient wear resistance cannot be obtained. On the other hand, if the ratio T / K is less than 0.15, although it depends on various conditions of the shaft part, the sliding surface may become too narrow. Generally, if the ratio T / K is 0.15 or more, since the sliding area will not be excessively reduced, even if a low-viscosity oil is used as the refrigeration machine oil 180, the wear resistance of the main shaft sliding part can be suitably realized by the sulfur-based sliding property improver.

[0161] Alternatively, in the second embodiment, in the main shaft sliding part, when the sliding surface is divided into a plurality of surfaces, an axial length different from the single sliding length T described above may be defined, and the ratio of the axial length to the outer diameter (diameter) of the sliding surface may be set to a predetermined value or less. Thereby, the sliding area can be reduced without substantially affecting the wear resistance.

[0162] Specifically, in the second embodiment, when the sliding surface is divided into a plurality of surfaces, when the sum of the axial lengths of the plurality of sliding surfaces is defined as the total sliding length Tt, the shaft part may be designed such that the ratio Tt / K of the total sliding length Tt to the outer diameter K is 1.26 or less (Tt / K ≤ 1.26).

[0163] For example, in the example shown in FIG. 4B, the sum of the length Ta of the first sliding surface 126a and the length Tb of the second sliding surface 126b is the total sliding length Tt (Tt = Ta + Tb). Therefore, in this example, it is sufficient that Ta + Tb ≤ 1.26. Also, in the example shown in FIG. 4C, the sum of the length Tc of the first sliding surface 126c, the length Td of the second sliding surface 126d, and the length Tf of the third sliding surface 126e is the total sliding length Tt (Tt = Tc + Td + Te). Therefore, in this example, it is sufficient that Tc + Td + Te ≤ 1.26.

[0164] In addition, the configuration where the ratio T / K based on the single sliding length T described above satisfies T / K ≤ 0.51 is referred to as the "first configuration of the main shaft sliding part" for convenience, and the configuration where Tt / K ≤ 1.26 based on the total sliding length Tt is referred to as the "second configuration of the main shaft sliding part". When only the first configuration is combined with the characteristic configuration in Embodiment 1, or only the second configuration is combined with the characteristic configuration in Embodiment 1, or both the first configuration and the second configuration are combined with the characteristic configuration in Embodiment 1, it is also possible.

[0165] FIG. 4A is an example when the first configuration is applied to the main shaft sliding part, and FIGS. 4B and 4C illustrate the case where both the first configuration and the second configuration are applied to the main shaft sliding part. Needless to say, the present disclosure is not limited to the configurations shown in FIGS. 4A to 4C. As described above, only the second configuration can be applied to the main shaft sliding part.

[0166] Thus, when the sliding surface has a plurality of surfaces, if the ratio T / K is 0.51 or less and the ratio Tt / K is 1.26 or less, in a state where the sliding area is reduced by using a low-viscosity oil (the kinematic viscosity at 40°C is in the range of 1.0 mm 2 / s to 2.5 mm 2 / s) as the refrigeration machine oil 180, the wear resistance of the main shaft sliding part derived from the sulfur-based sliding property improver described later can be made even better.

[0167] In the present disclosure, the lower limit value of the ratio Tt / K is not particularly limited, but as an example of a preferable lower limit value, 0.3 or more can be mentioned. Therefore, the preferable range of the ratio Tt / K in the present disclosure can be within the range of 0.3 to 1.26. Further, a more preferable lower limit of the ratio Tt / K can be 0.60, and an even more preferable lower limit can be 0.99. Generally, if the ratio Tt / K is 0.3 or more, even when the sliding surface is divided into a plurality of surfaces, the sliding area will not be excessively reduced. Therefore, even when a low-viscosity oil is used as the refrigeration machine oil 180, the wear resistance of the main shaft sliding part can be suitably realized by the sulfur-based sliding property improver.

[0168] In the examples shown in FIGS. 4A to 4C, the ratio T / K or the ratio Tt / K is described for the main shaft 124 of the crankshaft 120 as the shaft portion, but the present disclosure is not limited thereto, and the same applies to the eccentric shaft 122. In the second embodiment, as described in the first embodiment, the connecting portion of the eccentric shaft 122 and the connecting means 142 serves as a sliding portion. In other words, a part of the connecting means 142 that slidably connects the eccentric shaft 122 corresponds to an "eccentric bearing".

[0169] Therefore, when the sliding surface of the eccentric shaft 122 with the "eccentric bearing" (the connecting portion of the eccentric shaft 122 and the connecting means 142) is a single surface, when the axial length of the sliding surface is defined as a single sliding length T, or when the sliding surface of the eccentric shaft 122 is divided into a plurality of surfaces, when the axial length of the sliding surface with the minimum axial length is defined as the single sliding length T, the ratio T / K of the single sliding length T to the outer diameter K of the eccentric shaft 122 may be 0.51 or less. Further, when the total axial length of the plurality of sliding surfaces of the eccentric shaft 122 is defined as the total sliding length Tt, the ratio Tt / K of the total sliding length Tt to the outer diameter K of the eccentric shaft 122 may be 1.26 or less.

[0170] Therefore, in the second embodiment, in the refrigerant compressor 100, it is sufficient to satisfy the "first configuration" in which the ratio T / K is 0.51 or less in at least one of the main shaft 124 and the eccentric shaft 122 that are shaft portions. Alternatively, it is sufficient to satisfy the "second configuration" in which the ratio Tt / K is 1.26 or less in at least one of the main shaft 124 and the eccentric shaft 122. Further, in at least one of the main shaft 124 and the eccentric shaft 122, both the first configuration and the second configuration may be satisfied.

[0171] Therefore, if the sliding portion formed by the connecting portion of the eccentric shaft 122 and the connecting means 142 is defined as an "eccentric shaft sliding portion", all of the "main shaft sliding portions" in the description of the second embodiment can be replaced with the "eccentric shaft sliding portion". Further, when the above-described first configuration or second configuration is applied to the eccentric shaft sliding portion, it can also be expressed as the "first configuration of the eccentric shaft sliding portion" or the "second configuration of the eccentric shaft sliding portion".

[0172] [Sulfur-based sliding property modifier] The refrigerant oil 180 used in the second embodiment is the same as described in the first embodiment, and has a kinematic viscosity at 40 °C of 1.0 mm 2 / s to 2.5 mm 2 / s. A low-viscosity oil within this range may be used. A more specific configuration of the refrigerant oil 180 in the present disclosure will be described in the embodiments described later.

[0173] Here, in the second embodiment, the low-viscosity oil, which is the refrigerant oil 180, contains a sulfur-based sliding property modifier. As described in the first embodiment, in the refrigerant compressor 100 according to the present disclosure, the crankshaft 120 is made of an iron-based material. The specific type of the iron-based material is not particularly limited, and examples thereof include metal materials containing iron as a main component, such as various known cast irons and steel materials. As the sulfur-based sliding property modifier, any material that can react with such an iron-based material and sulfur may be used.

[0174] Therefore, the sliding property modifier in the second embodiment may be sulfur itself, or a sulfur compound that contains sulfur and can react with the iron-based material. For example, sulfur compounds that can be used as the sliding property modifier include sulfurized olefins, sulfide-based compounds (e.g., dibenzyl (di)sulfide (DBDS), etc.), xanthates, thiadiazoles, thiocarbonates, sulfurized fats and oils, sulfurized esters, dithiocarbamates, sulfurized terpenes, and the like.

[0175] The content of the sulfur-based sliding property modifier in the refrigerant oil 180 is not particularly limited. Typically, the sliding property modifier may be added to the refrigerant oil 180 so that the sulfur element weight (mass) is 100 ppm or more. The lower limit value of the addition amount (content) of the sliding property modifier, which is 100 ppm in terms of sulfur element weight, is larger than the upper limit value of the general addition amount of the sulfur-based extreme pressure additive described later.

[0176] If the content (addition amount) of the sliding property improver is less than 100 ppm in terms of the weight of sulfur element, depending on various conditions, when using a low-viscosity refrigerant oil 180 and reducing the sliding area of the main shaft sliding part, it may not be possible to achieve suitable wear resistance of the main shaft sliding part. Further, as the lower limit of the preferable content of the sulfur-based sliding property improver, for example, 150 ppm or more can be mentioned in terms of the weight of sulfur element. Further, as the upper limit of the preferable content of the sulfur-based sliding property improver, for example, 1000 ppm or less can be mentioned in terms of the weight of sulfur element, and more preferably 500 ppm or less can be mentioned.

[0177] In the present disclosure, as the sulfur-based sliding property improver used, it is possible to use the same compounds as known sulfur-based extreme pressure additives, but those having relatively higher reactivity with the shaft material than known extreme pressure additives can be used, or an amount more than the general addition amount (content) of known extreme pressure additives can be added to the refrigerant oil 180.

[0178] Generally, extreme pressure additives are compounds containing active elements such as sulfur, halogen elements, and phosphorus, and chemically react with the material surface (sliding surface) of the sliding part to form a film, and this film suppresses wear, seizure, fusion, etc. of the sliding member. However, it is also very well known that compounds containing sulfur are likely to react with copper.

[0179] In the refrigerant compressor 100, a copper wire is used as the winding of the electric element 104. Further, in a refrigeration and refrigeration device using the refrigerant compressor 100, generally, a copper pipe is often used as the refrigerant pipe. As described above, since copper easily reacts with a compound containing sulfur and corrodes, when using a sulfur-based extreme pressure additive, it is necessary to take measures to avoid or suppress the corrosion of the copper members (or copper-containing members) provided in the refrigerant compressor 100 or the refrigeration and refrigeration device and not reduce its reliability.

[0180] Therefore, in the common general knowledge in the field of the refrigerant compressor 100, a technique of using a special compound in combination is known so that a sulfur-based extreme pressure additive does not react with a copper member or a copper-containing member included in the refrigerant compressor 100 or a refrigerating and freezing apparatus. Alternatively, it is also known not to use a sulfur-based compound as an additive in the first place.

[0181] On the other hand, as a result of the inventors' intensive studies including experimental verification, when a low-viscosity refrigerant oil 180 is used and the sliding area of the main shaft sliding portion is reduced so that the ratio T / K described above becomes 0.51 or less (first configuration of the main shaft sliding portion) or the ratio Tt / K described above becomes 1.26 or less (second configuration of the main shaft sliding portion), as a sliding property improver, not only can good wear resistance be achieved by using a more reactive sulfur-based compound or increasing the addition amount (content), but it has also become clear that corrosion of a copper member (or a copper-containing member) can be substantially avoided.

[0182] It is widely known in the field of lubricating oils that the sliding property improver and the extreme pressure additive are clearly different components.

[0183] When the oil film breaks in the sliding portion and metal contact occurs between the sliding members, the surface layer (for example, oxide layer) is removed from the contact portion of each sliding surface and metal protrusions are newly generated. These metal protrusions generated on the sliding surface may fuse with each other. The sliding property improver forms a film (wear prevention film) in place of the removed surface layer. Thereby, fusion of the metal protrusions with each other can be prevented in advance, so that wear in the sliding portion can be favorably suppressed.

[0184] On the other hand, the extreme pressure additive rapidly forms a film (extreme pressure film, EP film) in place of the removed surface layer. This EP film is more firmly formed on the sliding surface than the wear prevention film formed by the sliding property improver. This is because the extreme pressure additive is targeted at suppressing wear in a lubrication state where the contact pressure between the sliding surfaces is relatively high and the oil film is likely to break, that is, in a "severe pressure state" of the sliding portion.

[0185] Generally, as an additive added to the refrigeration oil 180 for the purpose of wear suppression in the sliding part of the refrigerant compressor 100, an extreme pressure additive can be mentioned. On the other hand, it is not common to add a sliding property modifier whose film formation rate is slower than that of the extreme pressure additive. However, in the second embodiment, when a sulfur-based sliding property modifier is added, it is assumed that a film is formed at a gentle speed in the main shaft sliding part, and sulfur is likely to be localized (biased) in the main shaft sliding part.

[0186] Thereby, even if a sulfur-based compound (sulfur-based extreme pressure additive) having a concentration higher than normal is added, not only can good slidability be realized in the main shaft sliding part, but also corrosion of the copper-made member (or copper-containing member) provided in the refrigerant compressor 100 or the refrigerating and freezing device is considered to be suppressed.

[0187] Thus, in the second embodiment, as the refrigeration oil 180, in the refrigerant compressor 100 using a low-viscosity oil having a kinematic viscosity at 40 ° C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, at least any one of the high-speed configuration of the piston average speed (V), the setting configuration of the ratio S / D, and the setting configuration of the ratios L1 / D and L2 / L1 described in the first embodiment is applied. Further, at least in the main shaft sliding part, a first configuration in which the ratio T / K of the single sliding length T to the outer diameter K of the shaft part is 0.51 or less, or a second configuration in which the ratio Tt / K of the total sliding length Tt to the outer diameter K of the shaft part is 1.26 or less (or both the first configuration and the second configuration) and a configuration using a sulfur-based sliding property modifier are applied.

[0188] By applying at least any one of the components described in the first embodiment, even when a low-viscosity oil is used as the refrigerant oil 180, leakage of the refrigerant gas 181 can be suppressed well, and in the refrigerant compressor 100, a further better coefficient of performance (COP) can be realized. Further, by applying the first configuration or the second configuration described in the second embodiment and the configuration using a sulfur-based sliding improver, the main shaft sliding portion can be lubricated well, and wear of the main shaft sliding portion can be suppressed well. As a result, the reliability of the refrigerant compressor 100 can be made even better.

[0189] Moreover, in the present disclosure, if the refrigerant compressor 100 is configured to be inverter-driven, there are cases where the electric element 104 is operated at a low rotational speed (low-speed operation) and cases where it is operated at a high rotational speed (high-speed operation). In particular, in the present disclosure, there may be cases where the operation frequency is low-speed operation at 16 r / s or more and 35 r / s or less. Generally, in low-speed operation, the oil supply capacity of the oil supply mechanism 125 provided in the crankshaft 120 decreases, so the supply amount of the refrigerant oil 180 to each sliding portion tends to decrease.

[0190] In the present disclosure, as described in the first embodiment, even during low-speed operation, the average piston speed can be increased or the viscous force of the oil film can be increased. Therefore, an increase in sliding loss can be suppressed also in the cylinder sliding portion, and leakage of the refrigerant gas 181 can also be suppressed. Thereby, a good coefficient of performance (COP) can be realized.

[0191] On the other hand, in the main shaft sliding portion, by applying the first configuration or the second configuration, the sliding area between the main shaft 124 and the main bearing 134 becomes relatively small, but good wear resistance can be realized even if the supply amount of the refrigerant oil 180 decreases. Therefore, an increase in sliding loss in the main shaft sliding portion can also be suppressed, so a good coefficient of performance (COP) can be realized.

[0192] Therefore, by applying a combination of the configuration described in the first embodiment and the configuration described in the second embodiment to the refrigerant compressor 100, it becomes possible to achieve an even better coefficient of performance (COP).

[0193] In addition, if both the first configuration and the second configuration are applied to the refrigerant compressor 100 in the main shaft sliding portion, the lubrication state in the main shaft sliding portion can be made even better. Therefore, the coefficient of performance (COP) can be made even better.

[0194] (Embodiment 3) The hermetic refrigerant compressor according to the third embodiment has a basic configuration similar to that of the hermetic refrigerant compressor according to the first embodiment, but has a more characteristic configuration with respect to the thrust bearing. Since the basic configuration of the hermetic refrigerant compressor according to the third embodiment is the same as the configuration shown in FIG. 1 shown in the first embodiment, a detailed description thereof is omitted.

[0195] [Thrust Bearing] An example of the specific configuration of the thrust bearing in the second embodiment will be specifically described with reference to FIGS. 5 and 6. FIGS. 5 and 6 are both schematic views of a part of the cross-sectional view of the refrigerant compressor 100 shown in FIG. 1. FIG. 5 schematically shows an example of the distances P and Q set for the thrust bearing provided in the refrigerant compressor 100 and an example of the load (main shaft load) applied to the main shaft sliding portion. FIG. 6 schematically shows an example of the main part configuration of the thrust bearing.

[0196] As shown in Fig. 1, in the refrigerant compressor 100, the main bearing 134 has a circular tube shape or a cylindrical shape that extends in the vertical direction with respect to the main body of the cylinder block 130 that spreads in the "lateral direction" inside the sealed container 102. The main body of the main bearing 134 extends below the cylinder block 130. And above the cylinder block 130, a tubular extension 137 extends as described in the first embodiment. Therefore, the main body of the main bearing 134 and the tubular extension 137 have a single circular tube shape or a cylindrical structure.

[0197] The inner peripheral surface of the main bearing 134 is a sliding surface as described above. Therefore, as shown in Fig. 5, the upper edge of the inner peripheral surface of the main bearing 134 is the upper end 138 of the sliding surface, and the lower edge of the main bearing 134 is the lower end 139 of the sliding surface. In the third embodiment, since the main bearing 134 has the tubular extension 137 on the upper side, the upper end 138 of the sliding surface corresponds to the upper edge of the inner peripheral surface of the tubular extension 137. In other words, it can be said that the tubular extension 137 is an "extension" that extends the main bearing 134 upward.

[0198] By providing such a tubular extension 137, when defining the upper limit of the distance Q described later, the total length of the main bearing 134 can be increased without increasing the total height of the refrigerant compressor 100, and the posture of the crankshaft 120 inserted into the main bearing 134 during operation can be improved.

[0199] As shown in Fig. 6, the inner surface of the upper end of the tubular extension 137 may be machined such as chamfering. In this case, the inner edge of the chamfered portion of the inner surface of the tubular extension 137 becomes the upper end 138 of the sliding surface of the main bearing 134. When the inner surface of the upper end of the tubular extension 137 is not machined such as chamfering, the upper edge of the inner surface of the tubular extension 137 becomes the upper end 138 of the sliding surface of the main bearing 134.

[0200] Then, as shown in FIG. 5, when the distance between the axis of the compression chamber 133 and the lower end 139 of the sliding surface of the main bearing 134 is defined as "distance P", and the distance between the axis of the compression chamber 133 and the upper end 138 of the sliding surface of the main bearing 134 is defined as "distance Q", in the refrigerant compressor 100 according to the present disclosure, even if a thrust bearing such as the thrust ball bearing 210 is provided, when the distance P is within the range of 38 mm to 51 mm, the distance Q is 16 mm or less.

[0201] In the third embodiment, a thrust bearing is provided on the thrust surface 136 of the main bearing 134 in the refrigerant compressor 100. The specific configuration of the thrust bearing is not particularly limited, and various rolling bearings may be used. In the third embodiment, as shown in FIGS. 1, 5, or 6, the thrust ball bearing 210 is used. As shown in FIG. 6, the thrust ball bearing 210 includes a lower race 206 located on the thrust surface 136, an upper race 202 located opposite to the lower race 206, and balls 204 as a plurality of rolling elements that are in rolling contact between them. Note that a vibration reduction member such as an elastic member may be provided between the thrust surface 136 of the main bearing 134 and the lower race 206.

[0202] The thrust ball bearing 210 is disposed on the outer peripheral side of the tubular extension portion 137, and the plurality of balls 204 are housed in a cage 205. The upper race 202 and the lower race 206 are, for example, annular metal flat plates and are arranged parallel to each other. Note that arc-shaped grooves may be provided in the upper race 202 and the lower race 206.

[0203] In the configuration example shown in FIG. 6, on the thrust surface 136, the lower race 206, the balls 204, and the upper race 202 are stacked in contact with each other in this order, and the flange portion 128 of the crankshaft 120 is seated on the upper surface of the upper race 202. Thereby, the thrust ball bearing 210 is configured.

[0204] The thrust ball bearing 210 is a rolling bearing in which the balls 204 roll in a point contact state with the upper race 202 and the lower race 206. Therefore, it is possible to rotate the main shaft 124 with less friction while supporting the vertical load by the thrust ball bearing 210. Note that the thrust ball bearing 210 is a "ball bearing" having balls 204 as rolling elements, but it may be a "roller bearing" having rollers as rolling elements, or other rolling bearings.

[0205] As a result, since the bearing function of the sliding bearing is changed to a rolling bearing such as the thrust ball bearing 210, the loss is reduced, so that the refrigerant compressor 100 can be effectively made more efficient. However, usually, by providing a thrust bearing such as the thrust ball bearing 210, the overall height of the refrigerant compressor 100 increases.

[0206] On the other hand, in the refrigerant compressor 100 according to the present disclosure, at distances P and Q based on the axis of the compression chamber 133, when the distance P is within the range of 38 mm to 51 mm, the distance Q is set to be 16 mm or less.

[0207] Generally, in order to reduce the sliding loss in the main shaft 124, a configuration for reducing the friction coefficient in the main shaft sliding portion and / or a configuration for reducing the load on the main shaft 124 (main shaft load F2) can be adopted. Further, in order to reduce the main shaft load F2, a configuration for reducing the distance Q and / or a configuration for increasing the distance P can be adopted.

[0208] However, if the distance P is increased, it is necessary to increase (raise) the overall height of the refrigerant compressor 100. When the overall height becomes large in this way, it is necessary to expand the engine room (machine room) of the refrigeration / air-conditioning device on which the refrigerant compressor 100 is mounted, which ultimately leads to a reduction in the internal volume of the refrigeration / air-conditioning device. Therefore, in order to reduce the main shaft load F2, it is assumed that the distance Q is reduced without changing the distance P.

[0209] However, if we simply try to reduce the distance Q, methods such as thinning the wall thickness of the support portion of the cylinder block 130 or thinning the thickness of the flange portion 128 to 4 mm or less, that is, methods of thinning a specific member (a part thereof) (thinning methods) may be considered.

[0210] However, if such a thinning method is adopted, it will result in deformation of other members. Specifically, if the support portion is thinned, the rigidity of the cylinder block 130 will decrease and the main bearing 134 will be more likely to deform. If the flange portion 128 is thinned, the inclination of the eccentric shaft 122 will increase. In particular, the increase in the inclination of the eccentric shaft 122 due to the thinning of the flange portion 128 has not been assumed conventionally.

[0211] In this way, although reducing the distance Q by the thinning method can improve the efficiency of the refrigerant compressor 100, there is a risk of reducing the reliability of the refrigerant compressor 100 due to the deformation of specific members.

[0212] On the other hand, in the third embodiment, as a result of experimental verification, it was uniquely found that by setting the upper limit of the distance Q to a predetermined value, that is, 16 mm or less, it is possible to achieve both high efficiency and good reliability without adopting the thinning method.

[0213] Specifically, it has become clear that when the distance Q is reduced, a slight inclination (tilt angle) of the eccentric shaft 122 that occurs during the operation of the refrigerant compressor 100 is related not only to the reliability of the refrigerant compressor 100 but also to the improvement of efficiency. In other words, this finding means that the change in the distance Q and the inclination of the eccentric shaft 122 are important factors in reducing the main shaft load F2 and realizing the high efficiency and good reliability of the refrigerant compressor 100. Therefore, as a result of intensive studies by the inventors, it has become clear that it is important to set the upper limit of the distance Q to 16 mm or less.

[0214] In Embodiment 3, when the distance P is set within the range of 38 mm to 51 mm, the distance Q is set to 16 mm or less, or the distance Q may be set within the range of 12 mm to 16 mm (i.e., 12 mm as an example of the lower limit value). Therefore, it is not necessary to greatly (increase) the overall height of the refrigerant compressor 100. As a result, not only can high efficiency be achieved while maintaining good quality (especially reliability) of the refrigerant compressor 100, but also since it is not necessary to expand the engine room (machine room) of the refrigerating and freezing apparatus, the internal volume of the refrigerating and freezing apparatus can be sufficiently ensured.

[0215] As described above, in Embodiment 3, in the refrigerant compressor 100 provided with a thrust bearing, when the distance P affecting the overall height is specified within a predetermined range, the upper limit of the distance Q between the axis of the compression chamber 133 and the upper end 138 of the sliding surface of the main bearing 134 is specified to 16 mm. As a result, without excessively thinning the flange portion 128 that contributes to the stability of the eccentric shaft 122, an increase in the overall height can be avoided, and the load on the main shaft 124 can be reduced without applying a special treatment to the sliding surface.

[0216] As a result, further high efficiency can be achieved without increasing the overall height of the refrigerant compressor 100. Moreover, since the flange portion 128 is not excessively thinned, it is also possible to achieve good reliability along with high efficiency.

[0217] Here, in order to reduce the sliding loss of the main shaft sliding portion, in addition to the configuration of reducing the distance Q, reducing the friction coefficient of the main shaft sliding portion can be mentioned. If simply reducing the friction coefficient, it is conceivable to make the viscosity of the refrigeration machine oil 180 as low as possible.

[0218] In the refrigerant compressor 100 according to the present disclosure, as described in Embodiment 1, as the refrigeration machine oil 180, the kinematic viscosity at 40°C is 1.0 mm 2 / s to 2.5 mm 2A very low-viscosity low-viscosity oil within the range of / s is used. Therefore, just by using this low-viscosity oil as the refrigeration oil 180, the friction coefficient can be reduced. Further, as described in Embodiment 3, by setting the distance Q of the refrigerant compressor 100 to 16 mm or less, the main shaft load F2 can be made even smaller. Thereby, the sliding loss of the main shaft sliding portion can be reduced.

[0219] Therefore, by combining the configuration described in Embodiment 3 and the configuration described in Embodiment 1, it becomes possible to achieve high efficiency and good reliability of the refrigerant compressor 100 not only in the cylinder sliding portion but also in the main shaft sliding portion. Thereby, the coefficient of performance (COP) of the refrigerant compressor 100 can be made even better.

[0220] Furthermore, in Embodiment 3, the diameter of the piston 140, that is, the piston diameter (D), or the inner diameter of the compression chamber 133 into which the piston 140 is inserted does not need to be particularly limited. When the distance P is within the range of 38 mm to 51 mm and the distance Q is set to 16 mm or less, it is not necessary to make the flange portion 128 excessively thin, and it is not necessary to substantially define the piston diameter (D) or the inner diameter of the compression chamber 133.

[0221] As described in Embodiment 1, by setting the ratio S / D of the stroke amount (S) to the piston diameter (D) within the range of 0.78 to 1.00, the viscous force (F1) of the oil film can be increased in the cylinder sliding portion (see the above formula (1)). Setting this ratio S / D leads to reducing the piston diameter (D), but in Embodiment 3, it is not necessary to substantially define the piston diameter (D). Therefore, the configuration described in Embodiment 3 also has the advantage of being easily applicable to the configuration described in Embodiment 1.

[0222] Also, according to the third embodiment, by setting the distance Q to 16 mm or less to reduce the main shaft load F2, it is possible to easily form a good oil film during low-speed operation even when using low-viscosity oil as the refrigerant oil 180. As described in the first embodiment, particularly in the present disclosure, there may be a case where low-speed operation is performed with an operating frequency of 16 r / s or more and 35 r / s or less.

[0223] Therefore, when applying the configuration described in the third embodiment to the configuration described in the first embodiment, it is possible to fully apply it even during low-speed operation, thereby effectively suppressing or avoiding wear or seizure in the main shaft sliding portion. Therefore, even when the refrigerant compressor 100 operates at low speed, the configuration described in the third embodiment is easy to apply to the configuration described in the first embodiment.

[0224] Also, as described in the second embodiment, by combining the configuration described in the first embodiment and the configuration described in the second embodiment, it is possible to further achieve a better coefficient of performance (COP) in the refrigerant compressor 100. And the configuration described in the third embodiment can also make the coefficient of performance (COP) even better by combining it with the configuration described in the first embodiment. Therefore, by combining the configurations described in the first embodiment, the second embodiment, and the third embodiment, a suitable synergistic effect can be exerted for the effect of achieving a good coefficient of performance (COP).

[0225] In the third embodiment, as shown in FIGS. 1 and 5, an eccentric shaft 122 is provided at the upper part (upper end) of the main shaft 124, and a piston 140 is connected to the eccentric shaft 122 via a connecting means 142. The piston 140 is reciprocally inserted into a compression chamber 133 arranged in the horizontal direction. That is, in the third embodiment, the piston 140 and the compression chamber 133 are located at the upper part inside the refrigerant compressor 100. However, the configuration of the refrigerant compressor 100 according to the present disclosure is not limited to this.

[0226] For example, although not shown in the drawings, an eccentric shaft 122 may be provided at the lower part (lower end) of the main shaft 124, so that the piston 140 and the compression chamber 133 may be located at the lower part within the refrigerant compressor 100. In this case, the distance P is the distance between the axis of the compression chamber 133 and the upper end of the sliding surface, and the distance Q is the distance between the axis of the compression chamber 133 and the lower end of the sliding surface.

[0227] Alternatively, in the third embodiment, as shown in FIG. 1, since the crankshaft 120 extends in the "vertical direction" (up and down direction) of the refrigerant compressor 100, the main shaft 124 and the eccentric shaft 122 also extend in the up and down direction. However, the configuration of the refrigerant compressor 100 according to the present disclosure is not limited to this. For example, the crankshaft 120 may extend in the "lateral direction" (a direction perpendicular to the vertical direction), and the piston 140 and the compression chamber 133 may be unevenly distributed in one of the lateral directions rather than the vertical direction within the refrigerant compressor 100. In this case, both ends of the sliding surface serving as the reference for the distance P and the distance Q are not located in the vertical direction but in the lateral direction.

[0228] Therefore, in the present disclosure, an end on the compression chamber 133 (or eccentric shaft 122) side of the sliding surface of the main bearing 134 is defined as the first end, and the end on the opposite side is defined as the second end. Therefore, the distance P can be defined as the distance between the axis of the compression chamber 133 and the second end of the sliding surface of the main bearing 134, and the distance Q can be defined as the distance between the axis of the compression chamber 133 and the first end of the sliding surface of the main bearing 134. In the third embodiment (the example shown in FIG. 1 or FIG. 5), the upper end 138 of the sliding surface is the first end, and the lower end 139 of the sliding surface is the second end.

[0229] Also, the refrigeration machine oil 180 used in the third embodiment may be the low-viscosity oil described above. However, as described in the fourth embodiment to be described later, as the low-viscosity oil, one containing a high-molecular-weight component (the preferred oil to be described later) can be used. With such a preferred oil, a better oil film can be formed at the sliding part. Thereby, the operational effects obtained by the configuration described in the third embodiment, and further, the operational effects obtained by the configuration described in the first embodiment (when the configuration described in the second embodiment is applied, its operational effects also) can be further improved.

[0230] (Embodiment 4) The hermetic refrigerant compressor according to Embodiment 4 has the same basic configuration as at least any one of the hermetic refrigerant compressors according to the above-described Embodiments 1 to 3, but the low-viscosity oil used as the refrigeration machine oil 180 has a more characteristic configuration. In Embodiment 4, a specific configuration example of the refrigeration machine oil 180 applicable to the refrigerant compressor 100 described in any one of Embodiments 1 to 3 will be described. Therefore, the specific description regarding the refrigerant compressor 100 is omitted.

[0231] As the refrigeration machine oil 180 according to the present disclosure, as described above, as long as it is a low-viscosity oil with a kinematic viscosity at 40 °C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, it is not particularly limited. As a typical refrigeration machine oil 180, for example, at least one oil substance selected from the group consisting of mineral oil, alkylbenzene oil, and ester oil can be preferably used. As a typical oil substance, mineral oil is mentioned as described above.

[0232] These oil substances may be used alone or in appropriate combinations of two or more. The combination of two or more oil substances here refers to, for example, not only the case of combining two or more different oil substances corresponding to mineral oil, but also, for example, the case of combining one or more oil substances corresponding to mineral oil and one or more oil substances corresponding to alkylbenzene oil (or one or more oil substances corresponding to ester oil).

[0233] The refrigeration machine oil 180 according to the present disclosure may contain various known additives in addition to the above-described oil substances. As such additives, various ones known in the field of refrigeration machine oil 180 can be preferably used, but typically, a sliding property modifier, an extreme pressure additive, an oiliness agent, an antioxidant, an acid scavenger, a metal deactivator, an antifoaming agent, a corrosion inhibitor, or a dispersant, etc. can be mentioned.

[0234] In particular, in the second embodiment, a sulfur-based sliding property improver is added to the low-viscosity oil used as the refrigeration oil 180. Further, a known extreme pressure additive may be added. As specific extreme pressure additives, known ones can be preferably used and are not particularly limited. For example, phosphorus-based compounds such as phosphate esters, and halogenated compounds such as chlorinated hydrocarbons or fluorinated hydrocarbons can be mentioned. These extreme pressure additives may be added to the low-viscosity oil (oil substance) alone or in an appropriate combination of two or more.

[0235] Among these extreme pressure additives, phosphorus-based compounds can be preferably used. Representative phosphorus-based compounds include tricresyl phosphate (TCP), tributyl phosphate (TBP), and triphenyl phosphate (TPP). Among them, TCP can be more preferably used. In particular, in the configuration described in the second embodiment, by adding a phosphorus-based extreme pressure additive in addition to the sulfur-based sliding property improver to the refrigeration oil 180, good wear reduction and the like can be realized in the main shaft sliding portion.

[0236] The addition amount of the extreme pressure additive to the low-viscosity oil is not particularly limited. For example, when the refrigeration oil 180 (oil substance) is a low-polarity substance such as mineral oil or alkylbenzene oil, it can be in the range of 0.5 to 8.0% by mass, and can also be in the range of 1 to 3% by mass when the total mass of the low-viscosity oil is 100% by mass.

[0237] Note that the sliding property improver, extreme pressure additive, or other additives may be added to the refrigeration oil 180 used in the configuration described in the first embodiment or the third embodiment. These additives can be added to the refrigeration oil 180 according to the present disclosure within a range that does not prevent the operational effects obtained by the configurations described in the first to third embodiments and that enables the operational effects derived from the additives to be obtained.

[0238] In other words, the refrigeration oil 180 used in the refrigerant compressor 100 according to the present disclosure has a kinematic viscosity at 40°C of 1.0 mm2 / s ~ 2.5 mm 2 It may be composed of an oily substance within the range of / s. When two or more kinds of oily substances are used to form an "oil composition", the kinematic viscosity of the oil composition at 40°C may be within the above range. Further, the refrigerant oil 180 according to the present disclosure may be an "oil composition" configured to contain a sulfur-based sliding property modifier (or other sliding property modifier), a phosphorus-based extreme pressure additive (or other extreme pressure additive), or other additives in addition to one or more kinds of oily substances.

[0239] Therefore, in the present disclosure, the oil composition used as the refrigerant oil 180 has a kinematic viscosity at 40°C of 1.0 mm 2 / s ~ 2.5 mm 2 / s, and can be referred to as a "low-viscosity oil".

[0240] Furthermore, the oily substance used in the refrigerant oil 180 according to the present disclosure only needs to have a molecular weight within a predetermined range. Specifically, the number average molecular weight Mn of the oily substance used as the refrigerant oil 180 may be 150 to 400. Also, the weight average molecular weight Mw (or mass average molecular weight) of the oily substance may be 150 to 400, and may be within the range of 200 to 300.

[0241] Furthermore, the polydispersity (PDI) of the oily substance, that is, the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, Mw / Mn, may be within the range of 1.0 to 1.1. The measurement methods of the oily substance and the molecular weights (number average molecular weight Mn and weight average molecular weight Mw) described later are not particularly limited, but in the present disclosure, standard polystyrene conversion by the GPC (Gel Permeation Chromatography) method can be mentioned.

[0242] Generally, when the viscosity of the oily substance used as the refrigeration oil 180 is reduced, the molecules of the oily substance are reduced in molecular weight. There is a concern about "deterioration of extractability" that such a low-molecular-weight oily substance is likely to extract components (extractable components) contained in the resin material present inside the refrigerant compressor 100 when it comes into contact with the resin material.

[0243] On the other hand, if at least the polydispersity Mw / Mn of the oily substance is in the range of 1.0 to 1.1, the variation in the molecular weight of the oily substance becomes small, so that the molecular weight of the oily substance is suppressed from becoming excessively small. Therefore, "deterioration of extractability" in the refrigeration oil 180, that is, the possibility that the refrigeration oil 180 extracts extractable components from the resin material used in the refrigerant compressor 100 can be significantly suppressed.

[0244] "Deterioration of extractability" in the refrigeration oil 180 means that extractable components extracted from the resin material are mixed into the low-viscosity oil used as the refrigeration oil 180, and as a result, the quality of the refrigeration oil 180 may be deteriorated. If the quality of the refrigeration oil 180 deteriorates, not only is it possible that good lubrication cannot be performed in the cylinder sliding portion or the main shaft sliding portion, but it is also possible that a good oil film cannot be formed in the cylinder sliding portion. In this case, it may not be possible to effectively suppress the leakage of the refrigerant gas 181 from between the piston 140 and the cylinder 132. Therefore, the molecular weight and polydispersity of the low-viscosity oil (the oily substance which is its main component) used as the refrigeration oil 180 may be within the above-mentioned ranges.

[0245] Furthermore, as described in the third embodiment, the refrigeration oil 180 according to the present disclosure may contain a component having a relatively large molecular weight, that is, a high-molecular-weight component, separately from the oily substance. Therefore, the refrigeration oil 180 according to the present disclosure may be, for example, an "oil composition" that contains an oily substance having a molecular weight within the predetermined range described above as a main component and further contains a high-molecular-weight component.

[0246] In the present disclosure, the oil composition (low-viscosity oil) as the refrigerant oil 180 is not limited to a configuration containing high-molecular-weight components. Therefore, in the following description, an oil composition containing high-molecular-weight components will be referred to as "suitable oil" for convenience of explanation.

[0247] The high-molecular-weight component contained in the suitable oil only needs to have a weight-average molecular weight Mw (mass-average molecular weight) of 500 or more. Also, the content of the high-molecular-weight component only needs to be 0.5 mass% or more when the total mass of the oil composition used as the refrigerant oil 180 is 100 mass%.

[0248] The suitable oil used as the refrigerant oil 180 in the fourth embodiment may originally contain a high-molecular-weight component, or may be configured to add an oily substance corresponding to the high-molecular-weight component so that the content is 0.5 mass% or more. As an example of the former, mineral oil can be cited, for example. When preparing (manufacturing) a suitable oil by refining unrefined or roughly refined raw mineral oil, the refining conditions or refining method of the raw oil may be adjusted so that 0.5 mass% or more of the high-molecular-weight component remains. As an example of the latter, for example, mineral oil, alkylbenzene oil, or polyalkylene glycol oil is used as the "main component" of the suitable oil, and an oily substance that becomes a high-molecular-weight component is added as an "additive component" to this main component.

[0249] The molecular weight and polydispersity of the oily substance that is the main component of the suitable oil only need to be within the ranges described above. If the molecular weight and polydispersity of the suitable oil are within this range, when the high-molecular-weight component is contained at 0.5 mass% or more, particularly in the configuration of the thrust bearing described in the third embodiment, when the distance Q is set to 16 mm or less, it becomes possible to form a suitable oil film in the main shaft sliding portion.

[0250] Regarding the upper limit of the content of the high molecular weight component, it is not particularly limited as long as it does not affect at least the function or effect as a suitable oil. However, representative examples of the upper limit of the content of the high molecular weight component can include 7.0% by mass or less, 6.0% by mass or less, and 5.0% by mass.

[0251] Depending on various conditions such as the specific configuration of the refrigerant compressor 100 or the specific composition of the refrigeration oil 180, if the content of the high molecular weight component exceeds 7.0% by mass, it may affect the viscosity of the oil (oil composition) used as the refrigeration oil 180. In this case, the kinematic viscosity of the oil (oil composition) at 40°C may exceed the range of 1.0 mm 2 / s to 2.5 mm 2 / s. Therefore, it may not be possible to obtain the effect of improving the coefficient of performance (COP) commensurate with the content of the high molecular weight component.

[0252] Also, as a reason for the improvement of the coefficient of performance (COP) of the refrigerant compressor 100 due to the suitable oil containing the high molecular weight component, from the results of experimental verification, even if the suitable oil has a low viscosity (the kinematic viscosity at 40°C is in the range of 1.0 mm 2 / s to 2.5 mm 2 / s), it is considered that the high molecular weight component contributes to the formation of a good oil film in the sliding part. Therefore, when a suitable oil containing a high molecular weight component is used as the refrigeration oil 180, it is considered that a better oil film will be formed not only in the main shaft sliding part but also in the cylinder sliding part. Therefore, not only can good lubrication in these sliding parts be realized, but further suppression of the leakage of the refrigerant gas 181 in the cylinder sliding part can also be expected.

[0253] When the suitable oil has a configuration in which a high molecular weight component is added to the main component, the specific material or type of the high molecular weight component is not particularly limited, and any oily substance with a weight average molecular weight Mw of 500 or more may be used. For example, when the main component is mineral oil, mineral oil may be used as the high molecular weight component, alkylbenzene oil may be used, polyalkylene glycol oil may be used, or other oily substances may be used.

[0254] Also, when the suitable oil is an oil composition obtained by adding a high molecular weight component as an additive component to the oily substance as the main component, for example, one type of oily substance may be used as the main component and one type of oily substance different from the main component may be used as the high molecular weight component. Alternatively, two or more types of oily substances may be used as the main component and one type of oily substance may be used as the high molecular weight component, or one type of oily substance may be used as the main component and two or more types of oily substances may be used as the high molecular weight component. Or, two or more mixtures of oily substances obtained by adding a high molecular weight component to the main component may be further mixed.

[0255] As described above, in the refrigerating machine oil 180 according to the fourth embodiment, one or more types of oily substances as the main component may contain a sliding property modifier (for example, sulfur or a sulfur-containing compound), an extreme pressure additive (for example, a phosphorus-containing compound), or other known additives. Here, when a suitable oil containing a high molecular weight component is used as the refrigerating machine oil 180, an oiliness agent may be particularly added as an additive. By the suitable oil containing an oiliness agent, an oil film of the suitable oil is more likely to be formed on the sliding surface of the sliding portion. Thereby, the reduction of friction in the sliding portion can be more suitably realized, and in the cylinder sliding portion, leakage of the refrigerant gas 181 can also be suppressed.

[0256] The specific types of the oiliness agent are not particularly limited, but typically, higher fatty acids, higher alcohols, esters (ester compounds), ethers, amines, amides, metal soaps, etc. can be mentioned. These oiliness agents may be used alone or in appropriate combination of two or more types. The addition amount of the oiliness agent is not particularly limited, but when the total mass of the suitable oil (oil composition) is 100% by mass, for example, it can be in the range of 0.01 to 1% by mass.

[0257] Among the above-mentioned oiliness agents, particularly typical ones include ester compounds. The ester compound may be any compound having an ester structure obtained by reacting an alcohol and a carboxylic acid. The alcohol may be monohydric or polyhydric alcohol with two or more valences. Similarly, the carboxylic acid may be monocarboxylic acid, dicarboxylic acid, or tricarboxylic acid (it may have four or more carboxy groups). Generally, commercially available ester-based oiliness agents can be preferably used.

[0258] If the suitable oil is an oil composition containing an oiliness agent, the ability to form an oil film can be further improved. That is, since the suitable oil contains high molecular weight components, high molecular weight components exist on the sliding surface of the sliding part (such as the main shaft sliding part or the cylinder sliding part), and thus it is considered that a good oil film can be formed. Furthermore, if the suitable oil contains an oiliness agent, it is considered that the oiliness agent is adsorbed on the sliding surface, thereby making it easier to form an oil film with the suitable oil (oil composition).

[0259] Particularly, if the oiliness agent is an ester-based compound, the oiliness agent will have an ester bond. Therefore, due to the polarity derived from this ester bond, it is possible to easily adhere an oil film formed by a suitable oil (oil composition) to the sliding part (improve the adhesion of the oil film). As a result, the ability to form an oil film of the suitable oil can be further improved, so that the friction coefficient can be further reduced, and the low friction of the sliding part can be more suitably realized. Furthermore, in the cylinder sliding part, a good oil film is likely to be formed between the piston 140 and the cylinder 132, so that the leakage of the refrigerant gas 181 can be better suppressed.

[0260] In addition, when the refrigerant oil 180 according to the fourth embodiment is the above-described suitable oil, as described above, as an additive, it may contain a sulfur-based sliding property modifier or a phosphorus-based extreme pressure additive. By containing these additives in the suitable oil, not only can the action effects obtained by each additive be imparted to the suitable oil, but also a synergistic effect by each additive can be expected. Therefore, not only can the sliding performance in each sliding part be made better, but also the leakage of the refrigerant gas 181 in the cylinder sliding part can be well suppressed.

[0261] On the other hand, the suitable oil does not necessarily have to contain at least any one, or all, of a sulfur-based sliding property modifier, a phosphorus-based extreme pressure additive, and an ester-based oiliness agent according to the specific configuration or various conditions of the refrigerant compressor 100. In other words, the suitable oil only needs to contain a suitable additive as necessary, and the specific additive is not limited to the above-described sulfur-based sliding property modifier, phosphorus-based extreme pressure additive, ester-based oiliness agent, etc. Also, as the refrigerant oil 180, a low-viscosity oil that does not contain high-molecular-weight components may be used.

[0262] (Embodiment 5) In this fifth embodiment, an example of a refrigerating and refrigerating device including the refrigerant compressor 100 described in the first to fourth embodiments will be specifically described with reference to FIG. 7.

[0263] The refrigerant compressor 100 according to the present disclosure can be widely and preferably used in various devices (refrigeration and refrigeration equipment) having a refrigeration cycle or a configuration substantially equivalent thereto. Specifically, for example, refrigerators (household refrigerators, commercial refrigerators), ice makers, showcases, dehumidifiers, heat pump water heaters, heat pump washing and drying machines, vending machines, air conditioners, air compressors, etc. can be mentioned, but it is not particularly limited. In the second embodiment, as an application example of the refrigerant compressor 100 according to the present disclosure, the article storage device shown in FIG. 7 is cited to explain the basic configuration of the refrigeration and refrigeration equipment.

[0264] As shown in FIG. 7, the refrigeration and refrigeration equipment according to the fifth embodiment includes a main body 301, a partition wall 304, a refrigerant circuit 305, etc. The main body 301 is composed of a heat-insulating box body and a door body, etc. The box body has a configuration in which one surface is open, and the door body has a configuration for opening and closing the opening of the box body. The inside of the main body 301 is partitioned into an article storage space 302 and a machine room 303 by a partition wall 304. A blower (not shown) is provided in the storage space 302. Note that the inside of the main body 301 may be partitioned into spaces other than the storage space 302 and the machine room 303.

[0265] The refrigerant circuit 305 is configured to cool the inside of the storage space 302, and includes the refrigerant compressor 100 described in each of the above embodiments, a radiator 307, a decompression device 308, and an absorber 309, and these are connected in a circular shape by piping. That is, the refrigerant circuit 305 is an example of a refrigeration cycle using the refrigerant compressor 100 according to the present disclosure.

[0266] As described above, a refrigerant gas 181 such as R600a is enclosed in the refrigerant compressor 100 (inside the sealed container 102). This refrigerant gas 181 is enclosed in a relatively low-temperature state so as to have the same pressure as the low-pressure side of the refrigeration and refrigeration equipment. Although the specific type of the refrigerant gas 181 is not particularly limited, a hydrocarbon-based one with a low global warming potential like R600a can be preferably used.

[0267] The heat absorber 309 of the refrigerant circuit 305 is disposed within the storage space 302. The cooling heat of the heat absorber 309 is agitated by a blower (not shown) so as to circulate within the storage space 302 as indicated by the dashed arrows in Fig. 7. Thereby, the interior of the storage space 302 is cooled.

[0268] Thus, the refrigerating and freezing apparatus according to the fifth embodiment mounts the refrigerant compressor 100 according to the first to fourth embodiments. When the refrigerant compressor 100 uses a low-viscosity oil having a kinematic viscosity at 40°C within the range of 1.0 mm 2 / s to 2.5 mm 2 / s, the coefficient of performance (COP) can be further improved. Therefore, the refrigerating and freezing apparatus mounting such a refrigerant compressor 100 can reduce its power consumption.

Example

[0269] The present invention will be described more specifically based on reference examples, examples, and conventional examples, but the present invention is not limited thereto. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention.

[0270] (Reference Example) In a conventional refrigerant compressor, a total of four types of mineral oils (1.8 mm 2 / s, 2.5 mm 2 / s, 3.3 mm 2 / s, and 5.0 mm 2 / s) having different kinematic viscosities at 40°C were used as the refrigerant oil 180 (changing the kinematic viscosity of the refrigerant oil 180), and when the operating frequency was 17 r / s, the amount of refrigerant gas 181 leaking from between the piston 140 and the cylinder 132 (refrigerant leakage amount) was evaluated. The results are shown in the graph of Fig. 8.

[0271] Note that the refrigerant leakage amount in the reference example was measured (evaluated) as follows. In the target refrigerant compressor (see Fig. 1), it was modified to block the suction hole (not shown in Fig. 1), and a container (refrigerant container) filled with a certain amount of refrigerant gas 181 was connected to the discharge hole side (not shown in Fig. 1) to prepare a measurement system for the refrigerant leakage amount. In this measurement system, since the suction hole is blocked, the refrigerant gas 181 is introduced into the hermetic refrigerant compressor through the space between the piston 140 and the cylinder 132 from the refrigerant container. Therefore, in this measurement system, the decrease in the pressure of the refrigerant container can be regarded as the refrigerant leakage amount. In this measurement system, the refrigerant leakage amounts when using four types of mineral oils with different kinematic viscosities were evaluated by operating the refrigerant compressor at an arbitrary frequency.

[0272] In the graph of Fig. 8, the horizontal axis represents the kinematic viscosity at 40 °C of the refrigeration oil 180 (unit: mm 2 / s), and the vertical axis represents the refrigerant leakage amount (unit: %). The evaluation criterion for the refrigerant leakage amount in Fig. 8 is based on the result when using the refrigeration oil 180 with a kinematic viscosity of 5.0 mm 2 / s at 40 °C as 100%.

[0273] As is clear from the results of Fig. 8, in the conventional refrigerant compressor, especially during low-speed operation (17 r / s), it can be seen that the refrigerant leakage amount clearly increases as the viscosity decreases.

[0274] (Method for evaluating the coefficient of performance) From the results of the reference example, it was clarified that in the conventional refrigerant compressor, during low-speed operation, if the kinematic viscosity at 40 °C is 2.5 mm 2 / s or less, the refrigerant leakage amount increases significantly. Therefore, in the refrigerant compressor 100 to which the configuration for increasing the piston average speed (V), the configuration for setting the ratio S / D, and the configuration for setting the ratios L1 / D and L2 / L1 described in the above Embodiment 1 are applied, how the coefficient of performance (COP) changes was evaluated. The above configurations applied to the refrigerant compressor 100 are shown in Table 1.

[0275]

Table 1

[0276] Also, the coefficient of performance (COP) in the refrigerant compressor 100 of the embodiment or the conventional refrigerant compressor was calculated as the ratio of the refrigerating capacity to the consumed energy (input) (refrigerating capacity / input). The evaluation criterion for the coefficient of performance (COP) was based on the result when using the refrigerating machine oil 180 with a kinematic viscosity of 5.0 mm 2 / s at 40°C as 100%.

[0277] (Example) The refrigerant compressor 100 according to the present disclosure, to which the configurations shown in Table 1 (piston average speed, ratio S / D, ratio L1 / D, ratio L2 / L1) are applied, was used, and a total of seven types of mineral oils with different kinematic viscosities at 40°C (1.8 mm 2 / s, 2.2 mm 2 / s, 2.3 mm 2 / s, 2.5 mm 2 / s, 2.7 mm 2 / s, 3.3 mm 2 / s, and 5.0 mm 2 / s) were used as the refrigerating machine oil 180 (changing the kinematic viscosity of the refrigerating machine oil 180), and its coefficient of performance (COP) was evaluated.

[0278] The results when the operating frequency is 27 r / s are shown in FIG. 9, and the results when the operating frequency is 17 r / s are shown in FIG. 10. In the graphs of FIGS. 9 and 10, the results of the examples are indicated by circular symbols. Also, in any of the graphs, the horizontal axis represents the kinematic viscosity of the refrigerating machine oil 180 at 40°C (unit: mm 2 / s), and the vertical axis represents the coefficient of performance (COP).

[0279] (Conventional Example) A conventional refrigerant compressor, that is, a refrigerant compressor having the same configuration as in the example except that the configuration shown in Table 1 is not applied, was used, and a total of five types of mineral oils with different kinematic viscosities at 40°C (1.8 mm 2 / s, 2.3 mm 2 / s, 2.7 mm 2 / s, 3.3 mm 2 / s, and 5.0 mm 2( / s) was used as the refrigeration oil 180 (while changing the kinematic viscosity of the refrigeration oil 180), and its coefficient of performance (COP) was evaluated. The results when the operating frequency was 27 r / s are shown in Fig. 9, and the results when the operating frequency was 17 r / s are shown in Fig. 10. In the graphs of Fig. 9 and Fig. 10, the results of the conventional example are shown by cross symbols.

[0280] (Comparison between the examples and the conventional example) As shown in Fig. 9, when the operating frequency is 27 r / s, for both the examples and the conventional example, when the kinematic viscosity of the refrigeration oil 180 is decreased, the coefficient of performance (COP) improves. This is because the viscous resistance of the refrigeration oil 180 becomes smaller, resulting in a smaller input power to the refrigerant compressor.

[0281] On the other hand, as shown in Fig. 10, when the operating frequency is lower at 17 r / s (during low-speed operation), in the conventional example, when the kinematic viscosity (at 40 °C) of the refrigeration oil 180 becomes 2.5 mm 2 / s or less, the coefficient of performance (COP) decreases. As described above, this is because when the kinematic viscosity of the refrigeration oil 180 becomes 2.5 mm 2 / s or less, the leakage amount of the refrigerant gas 181 between the piston 140 and the cylinder 132 increases, and the refrigeration capacity decreases.

[0282] On the other hand, in the examples, even when the kinematic viscosity (at 40 °C) of the refrigeration oil 180 is 2.5 mm 2 / s or less, the coefficient of performance (COP) improves. Therefore, in the refrigerant compressor 100 (the hermetic refrigerant compressor according to the present disclosure) to which the configuration shown in Table 1 is applied, as the refrigeration oil 180, when a low-viscosity oil having a kinematic viscosity (at 40 °C) in the range of 1.0 mm 2 / s to 2.5 mm 2 / s is used, it can be seen that a good coefficient of performance (COP) can be realized even during low-speed operation.

[0283] Also, as shown in Table 1, the average piston speed in the conventional example is 0.31 m / s at 17 r / s, while the average piston speed in the embodiment is 0.34 m / s at 17 r / s. As described above, in the embodiment, even when using a low-viscosity oil as the refrigerant oil 180, a good coefficient of performance (COP) can be achieved. However, in the conventional example, when using a low-viscosity oil as the refrigerant oil 180, a good coefficient of performance (COP) cannot be achieved. Therefore, it can be understood that within the range of 16 r / s to 35 r / s defined as the low-speed operation frequency in the present disclosure, if the average piston speed exceeds at least 0.31 m / s, a good coefficient of performance (COP) can be achieved.

[0284] (Appendix) From the descriptions of the above embodiments, the following technologies are disclosed in this specification.

[0285] (Technology 1) A hermetic compressor comprising a hermetic container, a refrigerant oil stored in the hermetic container and having a kinematic viscosity at 40 °C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block accommodated in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber, wherein when the operating frequency is 16 r / s or more and 35 r / s or less, the average speed of the reciprocating motion of the piston is set to exceed 0.31 m / s.

[0286] (Technology 2) The hermetic compressor according to Technology 1, wherein the ratio S / D of the stroke amount (S) of the reciprocating motion of the piston to the piston diameter (D) is in the range of 0.78 to 1.00.

[0287] (Technology 3) When the length of the region where the piston seals the compression chamber by its reciprocating motion is defined as the seal length (L2), the ratio L1 / D of the overall length (L1) of the piston to the piston diameter (D) is within the range of 0.8 to 1.0, and the ratio L2 / L1 of the seal length (L2) to the overall length (L1) of the piston is within the range of 0.9 to 1.0. The hermetic refrigerant compressor according to Technique 1 or Technique 2.

[0288] (Technique 4) A hermetic container, refrigerating machine oil stored in the hermetic container and having a kinematic viscosity at 40 °C within the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block housed in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber. The ratio S / D of the stroke amount (S) of the reciprocating motion of the piston to the piston diameter (D) is within the range of 0.78 to 1.00. The hermetic refrigerant compressor.

[0289] (Technique 5) When the length of the region where the piston seals the compression chamber by its reciprocating motion is defined as the seal length (L2), the ratio L2 / L1 of the seal length (L2) to the overall length (L1) of the piston is within the range of 0.9 to 1.0. The hermetic refrigerant compressor according to Technique 4.

[0290] (Technique 6) A hermetic container, refrigerating machine oil stored in the hermetic container and having a kinematic viscosity at 40 °C within the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block housed in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber. The ratio L1 / D of the overall length (L1) of the piston to the piston diameter (D) is within the range of 0.8 to 1.0, and when the length of the region where the piston seals the compression chamber by its reciprocating motion is defined as the seal length (L2), the ratio L2 / L1 of the seal length (L2) to the overall length (L1) of the piston is within the range of 0.9 to 1.0. The hermetic refrigerant compressor.

[0291] (Technology 7) The compression element includes, as a shaft portion, a crankshaft having a main shaft and an eccentric shaft, and as a bearing portion for supporting the shaft portion, a main bearing for supporting the main shaft and an eccentric bearing for supporting the eccentric shaft. A sliding surface of the main shaft with the main bearing is divided into a plurality of surfaces. When the total axial length of the plurality of sliding surfaces is defined as a total sliding length Tt, a ratio Tt / K of the total sliding length Tt to an outer diameter K of the main shaft is 1.26 or less. The hermetic refrigerant compressor according to any one of Technologies 1 to 6.

[0292] (Technology 8) The compression element includes, as a shaft portion, a crankshaft having a main shaft and an eccentric shaft, and as a bearing portion for supporting the shaft portion, a main bearing for supporting the main shaft and an eccentric bearing for supporting the eccentric shaft. A sliding surface of the main shaft with the main bearing is either a single surface or divided into a plurality of surfaces. When the sliding surface is a single surface, when an axial length of the sliding surface is defined as a single sliding length T, or when the sliding surface is divided into a plurality of surfaces, when an axial length of a sliding surface having a minimum axial length is defined as a single sliding length T, a ratio T / K of the single sliding length T to an outer diameter K of the main shaft is 0.51 or less. Further, the refrigerating machine oil contains sulfur or a compound having sulfur as a sliding property improver. The hermetic refrigerant compressor according to any one of Technologies 1 to 7.

[0293] (Technology 9) The compression element further includes a crankshaft having a main shaft and an eccentric shaft, a main bearing for supporting the main shaft, and a thrust bearing provided on a thrust surface of the main bearing. An end on the compression chamber side is defined as a first end and an end on the opposite side is defined as a second end on a sliding surface of the main bearing. When a distance between an axis of the compression chamber and a second end of the sliding surface of the main bearing is defined as P and a distance between the axis of the compression chamber and a first end of the sliding surface of the main bearing is defined as Q, when the distance P is within a range of 38 mm to 51 mm, the distance Q is 16 mm or less. The hermetic refrigerant compressor according to any one of Technologies 1 to 6.

[0294] (Technology 10) A hermetic container, a refrigerating machine oil stored in the hermetic container and having a kinematic viscosity at 40°C in the range of 1.0 mm 2 / s to 2.5 mm 2 / s, a cylinder block housed in the hermetic container and forming a compression chamber, and a piston reciprocally inserted inside the compression chamber. In a hermetic refrigerant compressor, when its operating frequency is 16 r / s or more and 35 r / s or less, an operating method of the hermetic refrigerant compressor in which an average speed of reciprocation of the piston exceeds 0.31 m / s.

[0295] (Technology 11) A refrigerating and refrigerating apparatus including the hermetic refrigerant compressor according to any one of Technologies 1 to 9, or a hermetic refrigerant compressor in which the operating method according to Technology 9 is executed, a radiator, a decompression device, and an absorber, and having a refrigerant circuit in which these are annularly connected by piping.

[0296] Note that the present invention is not limited to the description of the above embodiment, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments and a plurality of modification examples are also included in the technical scope of the present invention.

[0297] Also, from the above description, many improvements and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed only as an example and is provided for the purpose of teaching those skilled in the art the best mode of practicing the present invention. Without departing from the spirit of the present invention, the details of its structure and / or function can be substantially changed.

Industrial Applicability

[0298] As described above, according to the present invention, a hermetic refrigerant compressor can achieve a better coefficient of performance (COP) by using a refrigerating machine oil having a lower viscosity. Therefore, the present invention can be widely applied to various devices using a refrigeration cycle.

Explanation of Reference Numerals

[0299] 100: Hermetic refrigerant compressor 102: Hermetic container 104: Electric element 106: Compression element 108: Compressor body 120: Crankshaft 122: Eccentric shaft 124: Main shaft 125: Oil supply mechanism 126: Sliding surface 126a: First sliding surface 126b: Second sliding surface 126c: First sliding surface 126d: Second sliding surface 126e: Third sliding surface 127: Non-sliding outer peripheral surface (non-sliding surface) 127a: First non-sliding outer peripheral surface (non-sliding surface) 127b: Second non-sliding outer peripheral surface (non-sliding surface) 128: Flange portion 130: Cylinder block 132: Cylinder 133: Compression chamber 134: Main bearing 136: Thrust surface 137: Tubular extension 138: Upper end of sliding surface (first end) 139: Lower end of sliding surface (second end) 140: Piston 142: Connecting means 150: Stator 152: Rotor 180: Refrigeration oil 181: Refrigerant gas 190: Suspension spring 202: Upper race 204: Ball (rolling element) 205: Cage 206: Lower race 210: Thrust ball bearing (thrust bearing) 240: Conventional piston 301: Body 302: Storage space 303: Machine Room 304: Partition Wall 305: Refrigerant Circuit 307: Radiator 308: Pressure Reducing Device 309: Heat Absorber

Claims

1. A sealed container; The liquid stored in the sealed container has a kinetic viscosity of 1.0 mm at 40°C. 2 / s ~ 2.5 mm 2 / s range of refrigeration oil, The compressor comprises a cylinder block that is housed in the sealed container and forms a compression chamber, and a piston that is inserted into the compression chamber so as to be capable of reciprocating motion, When the operating frequency is 16 r / s or more and 35 r / s or less, the average speed at which the piston reciprocates is set to be greater than 0.31 m / s, The ratio S / D of the reciprocating stroke amount (S) of the piston to the piston diameter (D) is within a range of 0.78 to 1.

00. Hermetic refrigerant compressor.

2. A sealed container; The liquid stored in the sealed container has a kinetic viscosity of 1.0 mm at 40°C. 2 / s ~ 2.5 mm 2 / s range of refrigeration oil, The compressor comprises a cylinder block that is housed in the sealed container and forms a compression chamber, and a piston that is inserted into the compression chamber so as to be capable of reciprocating motion, When the operating frequency is 16 r / s or more and 35 r / s or less, the average speed at which the piston reciprocates is set to be greater than 0.31 m / s, When the length of the area where the piston seals the inside of the compression chamber by its reciprocating motion is defined as a seal length (L2), A ratio L1 / D of the piston overall length (L1) to the piston diameter (D) is within a range of 0.8 to 1.0, The ratio L2 / L1 of the seal length (L2) to the piston total length (L1) is within a range of 0.9 to 1.

0. Hermetic refrigerant compressor.

3. The compression element includes a crankshaft having a main shaft and an eccentric shaft as a shaft portion, and a main bearing supporting the main shaft and an eccentric bearing supporting the eccentric shaft as a bearing portion supporting the shaft portion, A sliding surface of the spindle with the main bearing is divided into a plurality of surfaces, and when a total axial length of the plurality of sliding surfaces is defined as a total sliding length Tt, a ratio Tt / K of the total sliding length Tt to an outer diameter K of the spindle is 1.26 or less.

3. The hermetic refrigerant compressor according to claim 1 or 2.

4. The compression element includes a crankshaft having a main shaft and an eccentric shaft as a shaft portion, and a main bearing supporting the main shaft and an eccentric bearing supporting the eccentric shaft as a bearing portion supporting the shaft portion, The sliding surface of the main shaft with the main bearing is a single surface or is divided into multiple surfaces, When the sliding surface is a single surface, the axial length of the sliding surface is defined as a single sliding length T, or when the sliding surface is divided into a plurality of surfaces, the axial length of the sliding surface having the shortest axial length is defined as the single sliding length T, and a ratio T / K of the single sliding length T to an outer diameter K of the spindle is 0.51 or less; Furthermore, the refrigerating machine oil contains sulfur or a compound having sulfur as a sliding property improver.

3. The hermetic refrigerant compressor according to claim 1 or 2.

5. A sealed container; The liquid stored in the sealed container has a kinetic viscosity of 1.0 mm at 40°C. 2 / s ~ 2.5 mm 2 / s range of refrigeration oil, The compressor comprises a cylinder block that is housed in the sealed container and forms a compression chamber, and a piston that is inserted into the compression chamber so as to be capable of reciprocating motion, A hermetic refrigerant compressor, wherein a ratio S / D of a stroke amount (S) of the piston to a piston diameter (D) is within a range of 0.78 to 1.00, When the operating frequency is 16 r / s or more and 35 r / s or less, the average speed at which the piston reciprocates exceeds 0.31 m / s. A method for operating a hermetic refrigerant compressor.

6. A sealed container; The liquid stored in the sealed container has a kinetic viscosity of 1.0 mm at 40°C. 2 / s ~ 2.5 mm 2 / s range of refrigeration oil, The compressor comprises a cylinder block that is housed in the sealed container and forms a compression chamber, and a piston that is inserted into the compression chamber so as to be capable of reciprocating motion, When the operating frequency is 16 r / s or more and 35 r / s or less, the average speed at which the piston reciprocates is set to be greater than 0.31 m / s, When the length of the area where the piston seals the inside of the compression chamber by its reciprocating motion is defined as a seal length (L2), A ratio L1 / D of the piston overall length (L1) to the piston diameter (D) is within a range of 0.8 to 1.0, A hermetic refrigerant compressor, wherein a ratio (L2 / L1) of the seal length (L2) to the piston overall length (L1) is within a range of 0.9 to 1.0, When the operating frequency is 16 r / s or more and 35 r / s or less, the average speed at which the piston reciprocates exceeds 0.31 m / s. A method for operating a hermetic refrigerant compressor.

7. A refrigerant circuit including the hermetic refrigerant compressor according to claim 1 or 2, a radiator, a pressure reducing device, and a heat sink, the refrigerant circuit being connected in a ring shape by piping. Refrigeration and freezing equipment.

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