Hermetic refrigerant compressor, its operating method, and freezing / refrigeration equipment 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 refrigerators, air conditioners, etc., a method for operating the hermetic refrigerant compressor, and a freezing / refrigerating device using the hermetic refrigerant compressor. [Background technology]

[0002] In recent years, from the viewpoint of protecting the global environment, development of highly efficient hermetic refrigerant compressors that reduce input power and the use of fossil fuels has been progressing. Reducing the operating frequency is an effective means of reducing the input power of hermetic refrigerant compressors.

[0003] On the other hand, regarding high efficiency, the coefficient of performance (COP), which is expressed as refrigeration capacity / input power, is an index that indicates the efficiency of a hermetic refrigerant compressor. To improve the coefficient of performance (COP), for example, it has been proposed to use oil (refrigeration oil, lubricant oil) with lower viscosity. For example, Patent Document 1 discloses a refrigerant compressor that achieves high efficiency by setting the viscosity of the oil stored inside the hermetic container to VG3 or more and VG8 or less. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2008-531896 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, efforts have been made to further reduce the viscosity of refrigeration oils in order to further improve the coefficient of performance (COP). For example, in the refrigerant compressor disclosed in Patent Document 1, the viscosity of the oil (refrigeration oil) is specified to be in the range of VG3 to VG8 as mentioned above, but in recent years, the use of refrigeration oils of VG3 or lower has also been considered. However, simply using a refrigeration oil with a lower viscosity to further reduce sliding loss is not sufficient to further improve the coefficient of performance (COP).

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to provide a hermetic refrigerant compressor that can achieve an even better coefficient of performance (COP) by using a refrigeration oil with a lower viscosity, a method for operating the same, and a freezing / refrigeration device using the same. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the hermetic refrigerant compressor according to the present disclosure includes a sealed container and a refrigerant having a kinematic viscosity of 1.0 mmHg at 40°C stored in the sealed container. 2 / s~2.5mm 2 The compressor may be configured to include a refrigerating machine oil having an operating frequency in the range of 16 r / s or more and 35 r / s or less, a cylinder block housed in the sealed container and forming a compression chamber, and a piston inserted into the compression chamber so as to be able to reciprocate, and when the operating frequency is 16 r / s or more and 35 r / s or less, the average reciprocating speed 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, a lower limit is set for the average speed of the reciprocating movement of the piston (average piston speed). As a result, even if the operating speed of the hermetic refrigerant compressor is relatively low, the average piston speed can be made relatively high. Therefore, as a refrigerating machine oil, the viscosity can be further reduced (kinematic viscosity at 40°C is 1.0 mmHg). 2 / s~2.5mm 2Even when using low-viscosity oil (set within the range of 1 / s), the piston reciprocating at high speed can form a good oil film between the piston and the compression chamber. As a result, it is possible to effectively suppress refrigerant gas leakage from the piston and compression chamber. Therefore, when low-viscosity oil is used as refrigeration oil, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0009] In order to solve the above-mentioned problems, the hermetic refrigerant compressor according to the present disclosure includes a sealed container and a refrigerant having a kinematic viscosity of 1.0 mmHg at 40°C stored in the sealed container. 2 / s~2.5mm 2 The refrigeration system may include a refrigeration oil having a viscosity in the range of 1 / s, a cylinder block accommodated in the sealed container and forming a compression chamber, and a piston inserted into the compression chamber so as to be able to reciprocate, wherein the ratio S / D of the reciprocating stroke amount (S) of the piston to the piston diameter (D) is in the range of 0.78 to 1.00.

[0010] According to the above configuration, the refrigerating machine oil has a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2 When using low-viscosity oil in the range of 1 / s, the ratio S / D is set within a predetermined range. This allows the stroke length (S) to be relatively large, which in turn allows the average piston speed to be relatively large. This effectively suppresses the amount of refrigerant gas leakage.

[0011] Furthermore, when the low-viscosity oil is used as the refrigeration oil, the piston diameter (D) can be made relatively small by setting the ratio S / D within a predetermined range, which reduces the total clearance area between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder, thereby effectively suppressing refrigerant gas leakage.

[0012] Furthermore, if the piston diameter (D) is relatively small, the compression load of the refrigerant gas on the piston can be reduced, which reduces the input power required to reciprocate the piston.

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

[0014] In order to solve the above-mentioned problems, the hermetic refrigerant compressor according to the present disclosure includes a sealed container and a refrigerant having a kinematic viscosity of 1.0 mmHg at 40°C stored in the sealed container. 2 / s~2.5mm 2 The refrigeration oil may include a refrigeration oil having a viscosity in the range of / s, 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 able to reciprocate, wherein 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, and when a seal length (L2) is defined as the length of an area where the piston seals the inside of the compression chamber by its reciprocating motion, 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.

[0015] According to the above configuration, the refrigerating machine oil has a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2 The ratios L1 / D and L2 / L1 are set within a predetermined range when using a low-viscosity oil in the range of 1 / s. This allows the seal length (L2) to be relatively long without excessively increasing the overall piston length (L1) while suppressing an increase in sliding loss. This allows the viscous force of the oil film between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder to be increased while suppressing an increase in sliding loss.

[0016] Furthermore, the area between the piston and the cylinder that is sealed by the oil film of refrigerating machine oil can be relatively increased, which further reduces leakage of refrigerant gas.

[0017] Furthermore, if the seal length (L2) is increased, it becomes possible to stabilize the position of the piston reciprocating in the compression chamber, which in turn makes it possible to further suppress an increase in sliding loss.

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

[0019] In order to solve the above-mentioned problems, the present disclosure also provides a method for operating a hermetic refrigerant compressor, comprising: a sealed container; and a refrigerant having a kinematic viscosity of 1.0 mmHg at 40°C stored in the sealed container. 2 / s~2.5mm 2 In a hermetic refrigerant compressor comprising a refrigerating machine oil having an operating frequency in the range of 16 r / s or more and 35 r / s or less, a cylinder block housed in the hermetic container and forming a compression chamber, and a piston inserted in the compression chamber so as to be able to reciprocate, 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 movement of the piston exceeds 0.31 m / s.

[0020] Furthermore, the refrigeration / freezing device according to the present disclosure may be configured to include a refrigerant circuit that includes a hermetic refrigerant compressor of the above-described configuration, a radiator, a pressure reducing device, and a heat absorber, and that connects these in a ring shape by piping.

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

[0022] With the above-described configuration, the present invention has the effect of providing a hermetic refrigerant compressor and an operating method thereof that can achieve an even better coefficient of performance (COP) by using a refrigeration oil with a lower viscosity, as well as a freezing / refrigeration device using the same. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a configuration of a hermetic refrigerant compressor according to an embodiment of the present disclosure. [Figure 2] 2 is a schematic enlarged side view of the configuration of a piston and a cylinder in a compression element included in the hermetic refrigerant compressor shown in FIG. 1. FIG. [Figure 3] FIG. 3A is a schematic side view showing an example of the configuration of a piston included in the hermetic refrigerant compressor shown in FIG. 1, and FIG. 3B is a schematic side view showing an example of the configuration of a conventional piston. [Figure 4] FIG. 4A is a schematic diagram showing an example of the configuration of a crankshaft included in the hermetic refrigerant compressor shown in FIG. 1, in which the sliding surface is a single surface. FIGS. 4B and 4C are schematic diagrams showing an example of the configuration of the crankshaft shown in FIG. 3A, in which the sliding surface is divided into a plurality of surfaces. [Figure 5] 2 is a partial cross-sectional view schematically showing an example of a distance P and a distance Q in the hermetic refrigerant compressor shown in FIG. 1, and a load (main shaft load) applied to a main shaft sliding portion. FIG. [Figure 6] 2 is a partial cross-sectional view schematically showing an example of a configuration of a main part of a thrust bearing in the hermetic refrigerant compressor shown in FIG. 1. FIG. [Figure 7] 2 is a schematic diagram showing an example of the configuration of a freezing / refrigeration device equipped with the hermetic refrigerant compressor shown in FIG. 1. FIG. [Figure 8] 1 is a graph showing a relationship (characteristic) of the amount of refrigerant gas leakage versus the kinematic viscosity of refrigerating machine oil when the operating frequency is 17 r / s in a conventional refrigerant compressor, as a reference example of the present disclosure. [Figure 9] 1 is a graph showing the relationship (characteristics) of the coefficient of performance (COP) with respect to the kinematic viscosity of the refrigerating machine oil when the operating frequency is 27 r / s, for an example of the present disclosure and a conventional example. [Figure 10] 1 is a graph showing the relationship (characteristics) of the coefficient of performance (COP) with respect to the kinematic viscosity of the refrigerating machine oil when the operating frequency is 17 r / s, for an example of the present disclosure and a conventional example. DETAILED DESCRIPTION OF THE INVENTION

[0024] (Findings that formed the basis of this 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 that it can reciprocate. Refrigeration oil exists as an oil film between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder (the inner circumferential surface of the compression chamber), lubricating the reciprocating motion (i.e., sliding) of the piston. For the sake of convenience, the space between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder is abbreviated as "piston-cylinder space." If the kinematic viscosity of the refrigeration oil is reduced, the oil film formed between the piston and cylinder becomes thinner. A thinner oil film reduces the sliding loss associated with the reciprocating motion (sliding) of the piston, but it is also possible that refrigerant gas may leak from between the piston and cylinder.

[0025] As will be explained in the examples below, the inventors of the present invention experimentally verified and evaluated the amount of refrigerant gas leaking from between the piston and cylinder in a hermetic refrigerant compressor having a conventional configuration, under conditions of a low operating frequency of, for example, 17 r / s (rps), using refrigerating machine oils with different kinematic viscosities at 40°C. As a result, it was found that the amount of refrigerating machine oil leaking from between the piston and cylinder was 2.5 mm kinematic viscosity at 40°C. 2 It was revealed that the amount of refrigerant gas leakage increases when the flow rate is below 1 / s.

[0026] Based on this verification and evaluation, the amount of refrigerant gas leakage tends to increase as the kinematic viscosity at 40°C of the refrigerant oil used decreases. However, even if the viscosity of the refrigerant oil is reduced, the amount of refrigerant gas leakage increases. 2 / s, it is believed that the reduction in friction loss within the hermetic refrigerant compressor can be more effective than the effect of an increase in the amount of refrigerant gas leakage, and as a result, the coefficient of performance (COP) can be improved.

[0027] However, the kinematic viscosity of the refrigerating oil at 40°C is 2.5 mm 2 / s or less, the amount of refrigerant gas leakage becomes too large, which reduces the refrigeration capacity of the refrigeration cycle equipped with a hermetic refrigerant compressor, making it impossible to improve the coefficient of performance (COP).

[0028] If it were possible to effectively suppress refrigerant gas leakage from between the piston and cylinder while reducing the kinematic viscosity of the refrigerant oil, it would be possible to further improve the coefficient of performance (COP) in hermetic refrigerant compressors. However, it is difficult to simultaneously reduce the viscosity of the refrigerant oil and suppress the amount of refrigerant gas leakage.

[0029] As a result of further intensive research, the inventors discovered that it is possible to improve the coefficient of performance (COP) by effectively suppressing the leakage of refrigerant gas from between the piston and cylinder, and thus completed the present invention.

[0030] That is, the hermetic refrigerant compressor according to the present disclosure comprises a sealed container and a refrigerant having a kinematic viscosity of 1.0 mmHg at 40°C stored in the sealed container. 2 / s~2.5mm 2 The compressor may be configured to include a refrigerating machine oil having an operating frequency in the range of 16 r / s or more and 35 r / s or less, a cylinder block housed in the sealed container and forming a compression chamber, and a piston inserted into the compression chamber so as to be able to reciprocate, and when the operating frequency is 16 r / s or more and 35 r / s or less, the average reciprocating speed of the piston is set 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, a lower limit is set for the average speed of the reciprocating movement of the piston (average piston speed). As a result, even if the operating speed of the hermetic refrigerant compressor is relatively low, the average piston speed can be made relatively high. Therefore, as a refrigerating machine oil, the viscosity can be further reduced (kinematic viscosity at 40°C is 1.0 mmHg). 2 / s~2.5mm 2 Even when using low-viscosity oil (set within the range of 1 / s), the piston reciprocating at high speed can form a good oil film between the piston and the compression chamber. As a result, it is possible to effectively suppress refrigerant gas leakage from the piston and compression chamber. Therefore, when low-viscosity oil is used as refrigeration oil, the coefficient of performance (COP) of the hermetic refrigerant compressor can be further improved.

[0032] In the hermetic refrigerant compressor having the above configuration, the ratio S / D of the stroke amount (S) of the 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 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, it is possible to relatively increase the stroke amount (S) or relatively decrease the piston diameter (D), as will be described later.

[0034] This effectively suppresses the amount of refrigerant gas leakage and reduces the input power required to reciprocate the piston, which in turn further improves the coefficient of performance (COP) of the hermetic refrigerant compressor when using low-viscosity oil as refrigeration oil.

[0035] Furthermore, in the hermetic refrigerant compressor having the above configuration, when the length of an area where the piston seals the inside of the compression chamber by its reciprocating motion is defined as a sealing length (L2), a ratio L1 / D of the piston overall length (L1) to the piston diameter (D) may be in the range of 0.8 to 1.0, and a ratio L2 / L1 of the sealing length (L2) to the piston overall length (L1) may be in the range of 0.9 to 1.0.

[0036] According to the above configuration, in addition to relatively increasing the average piston speed, the ratios L1 / D and L2 / L1 are set within predetermined ranges, which allows the seal length (L2) to be relatively long without excessively increasing the overall piston length (L1), as will be described later.

[0037] This increases the viscosity of the oil film between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder while suppressing an increase in sliding loss, and further suppresses refrigerant gas leakage, thereby further improving the coefficient of performance (COP) of the hermetic refrigerant compressor.

[0038] Another hermetic refrigerant compressor according to the present disclosure includes a sealed container and a refrigerant having a kinematic viscosity of 1.0 mmHg at 40°C stored in the sealed container. 2 / s~2.5mm 2 / s, a cylinder block housed in the sealed container and forming a compression chamber, and a piston inserted into the compression chamber so as to be able to reciprocate, wherein the ratio S / D of the reciprocating stroke amount (S) of the piston to the piston diameter (D) is within the range of 0.78 to 1.00.

[0039] According to the above configuration, the refrigerating machine oil has a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2 When using low-viscosity oil in the range of 1 / s, the ratio S / D is set within a predetermined range. This allows the stroke length (S) to be relatively large, which in turn allows the average piston speed to be relatively large. This effectively suppresses the amount of refrigerant gas leakage.

[0040] Furthermore, when the low-viscosity oil is used as the refrigeration oil, the piston diameter (D) can be made relatively small by setting the ratio S / D within a predetermined range, which reduces the total clearance area between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder, thereby effectively suppressing refrigerant gas leakage.

[0041] Furthermore, if the piston diameter (D) is relatively small, the compression load of the refrigerant gas on the piston can be reduced, which reduces the input power required to reciprocate the piston.

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

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

[0044] According to the above configuration, the ratio S / D of the piston stroke (S) to the piston diameter (D) is set within a predetermined range, and the ratios L1 / D and L2 / L1 are also set within predetermined ranges. By setting these ratios, as will be described later, it is possible to relatively increase the seal length (L2) without excessively increasing the overall piston length (L1).

[0045] This increases the viscosity of the oil film between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder while suppressing an increase in sliding loss, and further suppresses refrigerant gas leakage, thereby further improving the coefficient of performance (COP) of the hermetic refrigerant compressor.

[0046] Another hermetic refrigerant compressor according to the present disclosure includes a sealed container and a refrigerant having a kinematic viscosity of 1.0 mmHg at 40°C stored in the sealed container. 2 / s~2.5mm 2 / s, 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 able to reciprocate, wherein the ratio L1 / D of the piston overall length (L1) to the piston diameter (D) is within a range of 0.8 to 1.0, and 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), the ratio L2 / L1 of the seal length (L2) to the piston overall length (L1) is within a range of 0.9 to 1.0.

[0047] According to the above configuration, the refrigerating machine oil has a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2The ratios L1 / D and L2 / L1 are set within a predetermined range when using a low-viscosity oil in the range of 1 / s. This allows the seal length (L2) to be relatively long without excessively increasing the overall piston length (L1) while suppressing an increase in sliding loss. This allows the viscous force of the oil film between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder to be increased while suppressing an increase in sliding loss.

[0048] Furthermore, the area between the piston and the cylinder that is sealed by the oil film of refrigerating machine oil can be relatively increased, which further reduces leakage of refrigerant gas.

[0049] Furthermore, if the seal length (L2) is increased, it becomes possible to stabilize the position of the piston reciprocating in the compression chamber, which in turn makes it possible to further suppress an increase in sliding loss.

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

[0051] In the hermetic refrigerant compressor having any of the above configurations, the compression element may include, as a shaft portion, a crankshaft having a main shaft and an eccentric shaft, and, as bearing portions supporting the shaft portion, a main bearing supporting the main shaft and an eccentric bearing supporting the eccentric shaft, wherein a sliding surface of the main shaft with the main bearing is divided into a plurality of surfaces, and when the sum of the axial lengths of the plurality of sliding surfaces is a total sliding length Tt, a ratio Tt / K of the total sliding length Tt to an outer diameter K of the main shaft may be 1.26 or less.

[0052] According to the above configuration, by applying the configuration for setting the ratio Tt / K and the configuration for using a sulfur-based sliding property modifier, even when a low-viscosity lubricant is used to reduce the sliding area, the main shaft sliding part consisting of the main shaft and main bearing can be well lubricated and wear of the main shaft sliding part can be well suppressed. As a result, the reliability of the refrigerant compressor can be further improved. Moreover, even when operating at a low rotation speed of 16 r / s or more and 35 r / s or less, good wear resistance can be achieved even when the supply amount of refrigeration oil is reduced. Therefore, an increase in sliding loss in the main shaft sliding part can be suppressed, and a good coefficient of performance (COP) can be achieved.

[0053] In the hermetic refrigerant compressor of 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 bearing portions supporting the shaft portion, a main bearing supporting the main shaft and an eccentric bearing supporting the eccentric shaft, wherein a sliding surface of the main shaft with the main bearing is a single surface or is divided into multiple surfaces, and 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 multiple surfaces, the axial length of the sliding surface with 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 main shaft is 0.51 or less, and further, the refrigerating 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 T / K ratio and the configuration for using a sulfur-based sliding property modifier, even when a low-viscosity lubricant is used to reduce the sliding area, the main shaft sliding part consisting of the main shaft and main bearing can be well lubricated and wear of the main shaft sliding part can be well suppressed. As a result, the reliability of the refrigerant compressor can be further improved. Moreover, even when operating at a low rotation speed of 16 r / s or more and 35 r / s or less, good wear resistance can be achieved even when the supply amount of refrigeration oil is reduced. Therefore, an increase in sliding loss in the main shaft sliding part can be suppressed, and a good coefficient of performance (COP) can be achieved.

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

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

[0057] The present disclosure also includes a method for operating a hermetic refrigerant compressor. That is, the method for operating a hermetic refrigerant compressor according to the present disclosure includes a sealed container and a refrigerant having a kinematic viscosity of 1.0 mmHg at 40°C stored in the sealed container. 2 / s~2.5mm 2In a hermetic refrigerant compressor comprising a refrigerating machine oil having an operating frequency in the range of 16 r / s or more and 35 r / s or less, a cylinder block housed in the hermetic container and forming a compression chamber, and a piston inserted in the compression chamber so as to be able to reciprocate, 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 movement of the piston exceeds 0.31 m / s.

[0058] The present disclosure also includes a refrigeration / freezer using a hermetic refrigerant compressor having the above configuration or a hermetic refrigerant compressor that executes the operating method of the above configuration. That is, the refrigeration / freezer according to the present disclosure may be configured to include a refrigerant circuit that includes a hermetic refrigerant compressor having the above configuration (or a hermetic refrigerant compressor that executes the operating method of the above configuration), a radiator, a pressure reducing device, and a heat absorber, and that connects these in a ring shape with piping.

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

[0060] 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 a 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 sometimes abbreviated as refrigerant compressor 100) according to a first embodiment of the present disclosure.

[0062] 1, refrigerant compressor 100 has a sealed container 102 filled with, for example, R600a as refrigerant gas 181, and mineral oil stored in the bottom as refrigeration oil 180. A compressor body 108 is housed in sealed container 102 and is elastically supported by suspension springs 190. Compressor body 108 also includes an electric element 104 and a compression element 106.

[0063] Electric element 104 is composed of at least a stator 150 and a rotor 152. Compression element 106 is a reciprocating element driven by electric element 104, and includes a crankshaft 120, a cylinder block 130, pistons 140, and connecting means 142. Crankshaft 120 is composed of at least a main shaft 124 to which rotor 152 is shrink-fitted, and an eccentric shaft 122 formed eccentrically relative to main shaft 124. In this embodiment, crankshaft 120 is made of, for example, an iron-based material.

[0064] In addition, a flange portion 128 is provided between the main shaft 124 and the eccentric shaft 122. As indicated by the dashed 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 misaligned. 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] The eccentric shaft 122 of the crankshaft 120 is located above the refrigerant compressor 100, and the main shaft 124 is located below the refrigerant compressor 100. Therefore, this up-down positional relationship (direction) is also used when describing 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, and the lower end of the main shaft 124 faces the lower inner surface of the sealed container 102 and is immersed in refrigerating machine oil 180. In addition, the crankshaft 120 is provided with an oil supply mechanism 125, which supplies refrigerating machine oil 180 from the lower end of the main shaft 124 immersed in the refrigerating machine oil 180 to the upper end of the eccentric shaft 122. As will be described later, the refrigerating machine oil 180 lubricates each sliding part of the refrigerant compressor 100 and also serves as a seal between the compression chamber 133 and the piston 140.

[0067] The outer circumferential surface of the main shaft 124 of the crankshaft 120 includes sliding surfaces 126a and 126b and a non-sliding outer circumferential surface 127. For ease 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 circumferential surface 127 is located between the first sliding surface 126a and the second sliding surface 126b.

[0068] In this disclosure, the term "sliding surface" refers to the outer or inner peripheral surface of a plurality of sliding members constituting the sliding portion, which is in slidable contact with the inner or outer peripheral surface of the other. The term "non-sliding outer peripheral surface (non-sliding surface)" refers to a surface that, unlike the sliding surface, does not contact the inner or outer peripheral surface of the other. In this 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 and 126b (the outer diameter is narrowed, or the non-sliding outer peripheral surface is recessed from the sliding surfaces 126a and 126b, or is hollowed out).

[0069] Cylinder block 130 includes cylinder 132 and main bearing 134. Cylinder 132 defines a compression chamber 133 therein. Main bearing 134 rotatably supports main shaft 124. In this embodiment, cylinder 132 and main bearing 134 are integrally formed as one cylinder block 130 from, for example, cast iron.

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

[0071] Non-sliding outer peripheral surface 127 of main shaft 124 is located between the upper end and lower end of main bearing 134. Therefore, when main shaft 124 is supported by main bearing 134, the upper end of main bearing 134 contacts first sliding surface 126a of main shaft 124, and the lower end of main bearing 134 contacts second sliding surface 126b. At this time, non-sliding outer peripheral surface 127, which has an outer diameter smaller than sliding surfaces 126a and 126b, does not contact the inner peripheral surface (sliding surface) of main bearing 134, and is not exposed from the upper end or lower end of main bearing 134.

[0072] In this embodiment, main bearing 134 includes thrust surface 136 and tubular extension 137. Thrust surface 136 of main bearing 134 is a flat surface that extends in a direction (vertical, horizontal) perpendicular to the axis, i.e., the extension direction (up-down direction) of main shaft 124.

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

[0074] The cylinder 132 is provided in the main body of the cylinder block 130, and the interior of the cylinder 132 serves as a compression chamber 133. The compression chamber 133 is a cylindrical (columnar) bore that extends in the "lateral direction" inside the refrigerant compressor 100. The piston 140 is inserted into the compression chamber 133 so as to be able to reciprocate. Therefore, the compression chamber 133 is closed by the insertion of the piston 140. The direction in which the piston 140 reciprocates is the "lateral direction."

[0075] The connecting means 142 is made of, for example, an aluminum casting, and 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 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 between the rotor 152 and the stator 150, and is fixed to the legs of the cylinder block 130. The rotor 152 is also fixed to the main shaft 124 of the crankshaft 120.

[0077] Therefore, in the refrigerant compressor 100, when the rotor 152 is rotated by the electric element 104, the crankshaft 120 rotates. As described above, in the crankshaft 120, the axis of the eccentric shaft 122 is offset from 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 inserted into the compression chamber 133 in the cylinder 132 so as to be able to reciprocate. Therefore, when the crankshaft 120 rotates, the rotation of the eccentric shaft 122 causes the piston 140 to reciprocate within the compression chamber 133.

[0078] As the crankshaft 120 rotates, the refrigerating machine oil 180 is supplied to each sliding part from the oil supply mechanism 125, as described above.

[0079] In this embodiment, the sliding parts include main shaft 124 and main bearing 134 of crankshaft 120, piston 140 and compression chamber 133 (cylinder 132), a connecting part between connecting means 142 and piston 140, and a connecting part between eccentric shaft 122 of crankshaft 120 and connecting means 142. Each of these members constituting the sliding parts is a sliding member.

[0080] Of these sliding parts, the sliding part formed by piston 140 and compression chamber 133 (cylinder 132) is referred to as the "cylinder sliding part" for the sake of convenience. Furthermore, the sliding part formed by main shaft 124 of crankshaft 120 and main bearing 134 is referred to as the "main shaft sliding part" for the sake of convenience.

[0081] The specific configuration of the refrigerant compressor 100 according to the present disclosure is not limited to the configuration shown in Fig. 1. The refrigerant compressor 100 according to the present disclosure may have any configuration as long as it includes an electric element 104 and a compression element 106, and the compression element 106 includes a cylinder block 130 having a compression chamber 133, and a piston 140 inserted into the compression chamber 133 so as to be capable of reciprocating.

[0082] 1, the electric element 104 is located on the lower side and the compression element 106 is located on the upper side within the sealed container 102. 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] 1, the electric element 104 is an inner rotor type, and the rotor 152 is rotatably disposed coaxially with the stator 150 on the inner periphery of the stator 150. However, the configuration of the electric element 104 is not limited to this, and the electric element 104 may be an outer rotor type, i.e., the rotor 152 is rotatably disposed coaxially with the stator 150 on the outer periphery of the stator 150.

[0084] 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, and as in a second embodiment described later, the sliding surface 126 of the main shaft 124 may form the entire outer peripheral surface of the main shaft 124, or the main shaft 124 may have three or more sliding surfaces 126.

[0085] The specific configuration of the refrigerating machine oil 180 used in the present disclosure is not particularly limited. In the present disclosure, the refrigerating machine oil 180 is a refrigerating machine oil having a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2 / s range (1.0 mm 2 / s or more 2.5mm 2 / s or less) (low-viscosity oil). The specific composition of the low-viscosity oil is not particularly limited, and in the first embodiment, for example, low-viscosity mineral oil is used, but as will be described in the fourth embodiment below, 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] In addition, the kinematic viscosity of the refrigerating machine oil 180 (low viscosity oil) in this disclosure at 40 ° C is 2.5 mm 2 If the refrigerant flow rate exceeds 1 / s, the viscous resistance becomes too large to achieve a good coefficient of performance (COP). If the viscous resistance becomes large, the input power to the refrigerant compressor 100 becomes large, making it impossible to achieve a good coefficient of performance (COP).

[0087] On the other hand, the kinematic viscosity of refrigerant oil 180 at 40°C is 1.0 mm 2 If the oil flow rate is less than 1 / s, the oil film formed on each sliding part inside the refrigerant compressor 100 becomes too thin. If the oil film becomes thin on the sliding parts, the possibility of breakage increases, and the sliding parts will not be able to obtain a good lubrication effect. This increases the metal contact between the sliding surfaces of the sliding parts, which may reduce the reliability of the sliding parts.

[0088] Here, the kinematic viscosity of the refrigerating machine oil 180 according to the present disclosure at 40°C may be within the above range, but the upper or lower limit may be changed as appropriate within the above range depending on various conditions. For example, the upper limit of the kinematic viscosity of the refrigerating machine oil 180 at 40°C is 2.4 mm. 2 The lower limit of the kinematic viscosity of the refrigerating machine oil at 180°C and 40°C is 1.5 mm 2 / s is also acceptable.

[0089] These upper and lower limits may be values ​​that include (below or above) the numerical value, or may be values ​​that do not include (below or above) the numerical value. For example, the upper limit is 2.5 mm. 2 / s may be less than 2.4 mm 2 / s or less, 2.4 mm 2 The kinematic viscosity of Refrigerating Machine Oil 180 at 40°C may be less than 2.4 mm / s. The lower limit is also the same. 2 / s or less, or 1.5 mm 2 By setting the viscosity at or above / s, it becomes easier to achieve a more suitable viscous resistance or a more suitable oil film thickness in terms of achieving a better coefficient of performance (COP).

[0090] [Refrigerant compressor operating method and piston configuration] Next, a method for operating a hermetic refrigerant compressor according to the present disclosure and a piston configuration in the hermetic refrigerant compressor will be described with reference to the above-described refrigerant compressor 100 shown in Figure 1. Note that the "piston configuration" here refers not only to the specific configuration of piston 140 itself, but also to the conditions set when piston 140 reciprocates within compression chamber 133.

[0091] In the refrigerant compressor 100, first, electric power is supplied from a commercial power source to the electric element 104, causing the rotor 152 of the electric element 104 to rotate. The rotation of the rotor 152 rotates the crankshaft 120 as described above, and the eccentric motion of the eccentric shaft 122 relative 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 the reciprocating motion of the piston 140, and the piston 140 is driven to reciprocate inside the cylinder 132, i.e., within the compression chamber 133. Refrigerant gas 181 introduced into the sealed container 102 is sucked into the compression chamber 133 by the reciprocating motion of the piston 140 and compressed.

[0092] Here, in the present disclosure, it is desirable that the refrigerant compressor 100 be inverter-driven at multiple 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 that controls the operation of the refrigerant compressor 100. The specific configuration of the inverter circuit is not particularly limited as long as it can rotate and drive the electric element 104 at multiple operating rotation speeds. The inverter circuit may be implemented as a chip, or may be a microprocessor or the like that operates by a program that executes rotation drive at multiple operating rotation speeds.

[0093] In the present disclosure, the operating frequency of the refrigerant compressor 100 is not particularly limited. Generally, lowering the operating frequency of the refrigerant compressor 100 can reduce its power consumption. However, in a refrigeration cycle (refrigeration / freezing device) equipped with the refrigerant compressor 100, the operating frequency may increase depending on the peak of the refrigeration capacity. Therefore, the operating frequency of the refrigerant compressor 100 is not always within a low range.

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

[0095] When low-viscosity oil is used as the refrigeration oil 180, sliding loss can be effectively reduced, but the lubricating effect on the sliding parts tends to decrease. Therefore, when the refrigeration oil 180 is low-viscosity oil, a method of avoiding or suppressing the decrease in lubricating effect is generally selected, for example, by applying a surface treatment to the sliding surfaces that constitute the sliding parts.

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

[0097] In contrast, in the present disclosure, the refrigerating machine oil 180 stored in the sealed container 102 has a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2 When using a low viscosity oil in the range of 16 r / s or more and 35 r / s or less, the inverter circuit (or controller) controls the operating frequency to be 16 r / s or more and 35 r / s or less, and the refrigerant compressor 100 is operated so that the average reciprocating speed of the piston 140 (average piston speed) exceeds 0.31 m / s.

[0098] By using this operating method, the kinematic viscosity of refrigerating machine oil 180 at 40°C is 2.5 mm 2 Even when a low-viscosity oil of 1 / s or less is used, the oil film of refrigerating machine oil 180 can exert a good viscous force (viscous resistance) between piston 140 and cylinder 132 at the "cylinder sliding portion," i.e., the sliding portion formed by piston 140 and compression chamber 133 in cylinder 132. This makes it possible to achieve good sliding performance at the cylinder sliding portion and also effectively suppress leakage of refrigerant gas 181.

[0099] Therefore, even when the refrigerant compressor 100 is operated within a low operating frequency range, that is, when the operating frequency is controlled within a range of 16 r / s to 35 r / s, an increase in the power consumption of the refrigerant compressor 100 can be suppressed or avoided, and a good coefficient of performance (COP) can be achieved in the refrigerant compressor 100.

[0100] On the other hand, if the oil film of refrigeration oil 180 cannot exert a good viscous force at the cylinder sliding portion, it becomes difficult to maintain a good oil film between piston 140 and cylinder 132 against the pressure of refrigerant gas 181 in compression chamber 133. This makes it easier for the oil film to break between piston 140 and cylinder 132, resulting in a significant amount of refrigerant gas 181 leaking.

[0101] The viscous force of the oil film of the refrigeration 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) enlarging a main part of the configuration of the cylinder sliding portion included in the refrigerant compressor 100 shown in Fig. 1.

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

[0103] When the viscous force (F1) of the oil film of the refrigerating machine oil 180 interposed between the piston 140 and the cylinder 132 is defined as the viscous force (F1), the viscous force (F1) can be expressed by the following equation (1) using 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 velocity (V). F1=(η×L2×V) / σ (1)

[0104] The seal length (L2) is the length of the area where piston 140 seals the inside of compression chamber 133 by its reciprocating motion. The viscous force (F1) of the oil film is a force directed from the outside to the inside of compression chamber 133, as shown schematically by the block arrow in Fig. 2. The clearance (σ) between piston 140 and cylinder 132 is also shown schematically in Fig. 2, and ideally, an oil film of refrigerating machine oil 180 fills the clearance (σ) without rupture.

[0105] If the viscosity force (F1) of the oil film becomes smaller, it becomes difficult for refrigeration oil 180 to maintain the state of an oil film between piston 140 and cylinder 132 against the pressure of refrigerant gas 181 filling compression chamber 133. This makes it easier for the oil film to break between piston 140 and cylinder 132, and as a result, a significant amount of refrigerant gas 181 is more likely to leak.

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

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

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

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

[0110] Furthermore, from the viewpoint of reducing the input power to the refrigerant compressor 100, the operating frequency may be lower than 13 r / s. However, if the operating frequency is set too low, sufficient reliability may not be obtained in terms of the coefficient of performance (COP) of the refrigerant compressor 100 and wear of the cylinder sliding parts. Therefore, a preferable lower limit of the operating frequency may be 16 r / s.

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

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

[0113] As mentioned above, the lower limit of the average piston velocity should be greater than 0.31 m / s, but may be 0.32 m / s or greater, or 0.34 m / s or greater, depending on various conditions. If the lower limit of the average piston velocity is 0.32 m / s or greater, the oil film of refrigerating machine oil 180 between piston 140 and cylinder 132 is more likely to exhibit good viscous force, depending on various conditions. This makes it possible to more effectively prevent leakage of refrigerant gas 181 from between piston 140 and cylinder 132.

[0114] In the present disclosure, a configuration can be adopted in which the ratio S / D of the stroke amount (S) of the reciprocating movement of piston 140 to the piston diameter (D) is set within a range of 0.78 to 1.00 (0.78≦S / D≦1.00) based on the above formula (1). The stroke amount (S) of the reciprocating movement of piston 140 is determined by twice the eccentric radius of eccentric shaft 122. This ratio S / D corresponds to the condition set when piston 140 reciprocates within compression chamber 133, and therefore 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 relatively long (larger), and therefore the average piston velocity (V) can be increased. As described above, if the average piston velocity (V) is increased, the viscous force (F1) of the oil film can be increased, making it easier to form an oil film between the piston 140 and the cylinder 132. This makes it possible to suppress leakage of the refrigerant gas 181.

[0116] Furthermore, when the ratio S / D is within the above range, an increase in stroke amount (S) means a relatively smaller piston diameter (D). By reducing the piston diameter (D), the total area of ​​the clearance (σ) between the piston 140 and the cylinder 132 can be reduced. A smaller total clearance area means that the "opening area" through which the refrigerant gas 181 may leak is narrowed. Therefore, it is possible to suppress 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 refrigerant gas 181 by piston 140 can be reduced. That is, when piston 140 reciprocates in compression chamber 133, the load applied to the tip surface of piston 140 from refrigerant gas 181 in compression chamber 133 becomes relatively smaller. This makes it possible to reduce the input power required to reciprocate piston 140. As a result, the coefficient of performance (COP) of refrigerant compressor 100 can be improved.

[0118] In the field of refrigerant compressors 100, the ratio S / D of the stroke length (S) to the piston diameter (D) has traditionally been considered desirable to be in the range of 0.4 to 0.8, as disclosed in "Hermetically Sealed Refrigerating Machines" by Mutsuyoshi Kawahira, published by the Japan Refrigeration Association in July 1981. In contrast, in the present disclosure, the ratio S / D is set to be in 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, low viscosity oil (kinematic viscosity at 40°C is 1.0 mm) is used as refrigerant oil 180. 2 / s~2.5mm 2When a ratio S / D is used (within the range of / s), it may become impossible to relatively increase the stroke amount (S) of the piston 140 and to relatively decrease the piston diameter (D). If the lower limit of the ratio S / D is 0.81 or more, the effect of relatively increasing the stroke amount (S) and relatively decreasing the piston diameter (D) can be more reliably achieved. If the lower limit of the ratio S / D is 0.84 or more, the above effect can be more reliably achieved.

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

[0121] The specific stroke amount (S) of the piston 140 is not particularly limited, but in this embodiment, the lower limit of the stroke amount (S) can be, for example, 19.5 mm or more. The lower limit of the stroke amount (S) may be 20 mm or more. On the other hand, the upper limit of the stroke amount (S) is not particularly limited, but if the stroke amount (S) is 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, the upper limit of the stroke amount (S) can be 30 mm or less.

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

[0123] On the other hand, if the clearance (σ) is less than 3 μm, particularly when low viscosity oil is used as refrigeration oil 180, reciprocating piston 140 may easily come into contact with the inner circumferential surface of cylinder 132 (compression chamber 133).

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

[0125] Of these ratios, the ratio L1 / D corresponds to the specific configuration (condition) of piston 140, and the ratio L2 / L1 corresponds to the condition set when piston 140 reciprocates within compression chamber 133. Therefore, these ratios can all be said to be the piston configuration described above.

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

[0127] 3A, in piston 140 used in refrigerant compressor 100 according to this embodiment, piston overall length (L1), i.e., the length along the direction of reciprocating motion of piston 140, is approximately equal to piston diameter (D), i.e., the diameter of piston 140. In addition, in piston 140, piston overall length (L1) is also approximately equal to seal length (L2), i.e., the length of the area that seals inside compression chamber 133 due to the reciprocating motion of piston 140.

[0128] In contrast to this, as shown in FIG. 3B, in 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) increases the viscosity force (F1) of the oil film of the refrigeration oil 180. Furthermore, a larger seal length (L2) means that the area sealed by the oil film in the cylinder sliding portion increases. Therefore, if the seal length (L2) is relatively large, it is possible to effectively suppress leakage of the refrigerant gas 181.

[0130] To ensure a sufficient seal length (L2), the piston overall length (L1) must also be large enough. On the other hand, if the piston overall length (L1) is too large, sliding loss at the cylinder sliding part increases. In particular, when the refrigerating machine oil 180 is a low viscosity oil (kinematic viscosity at 40°C is 2.5 mm), 2 / s or less), it becomes more difficult to form a good oil film on the sliding parts of the cylinder compared to oils with higher viscosities.

[0131] Therefore, after careful consideration of the criteria for setting the appropriate piston overall length (L1), it became clear that the piston diameter (D) should be used as the criteria, especially when the refrigeration oil 180 is a low viscosity oil.

[0132] 3A, if the ratio L1 / D is within the range of 0.8 to 1.0, the range of the overall piston length (L1) suitable for low-viscosity oil is defined in the cylinder sliding portion. This makes it possible to realize an overall piston length (L1) that can ensure an adequate sealing length (L2) while suppressing an increase in sliding loss.

[0133] If the ratio L1 / D is less than 0.8, the overall piston length (L1) becomes relatively short when low-viscosity oil is used as the refrigeration oil 180. As a result, a sufficient seal length (L2) cannot be ensured, and not only does the size of the area sealed by the oil film become insufficient, but the viscous force (F1) of the oil film based on the above formula (1) cannot be increased.

[0134] On the other hand, if the ratio L1 / D exceeds 1.0, as in the conventional piston 240 shown in Figure 3B, when low-viscosity oil is used as the refrigeration oil 180, the overall piston length (L1) becomes too long. This may result in an increase in sliding loss at the sliding parts of the cylinder. If the sliding loss increases, it becomes difficult to achieve a good coefficient of performance (COP).

[0135] In this disclosure, since low-viscosity oil is used as the refrigeration oil 180, it is desirable to make the seal length (L2) as long as possible. To achieve this, it is desirable to also make the overall piston length (L1) long, as described above. However, as described above, if the overall piston length (L1) is too long, sliding loss in the cylinder sliding parts increases.

[0136] Therefore, in the present disclosure, the ratio L2 / L1 is set within the range of 0.9 to 1.0. This allows the seal length (L2) to be relatively long without excessively increasing the overall piston length (L1), as in the piston 140 shown in Fig. 3A. 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 sliding loss in the cylinder sliding parts.

[0137] Moreover, since the seal length (L2) is relatively large compared to the overall piston length (L1), the area sealed by the oil film of refrigeration oil 180 is also relatively large. This makes it possible to further suppress leakage of refrigerant gas 181. Furthermore, if the seal length (L2) is large, it becomes possible to stabilize the posture of piston 140 reciprocating within compression chamber 133. As a result, it becomes possible to further suppress an increase in sliding loss.

[0138] In contrast, if the ratio L2 / L1 is less than 0.9, as in the case of conventional piston 240 shown in FIG. 3B, when low-viscosity oil is used as refrigeration oil 180, the seal length (L2) cannot be sufficiently secured. As a result, not only is the viscous force (F1) of the oil film unable to be increased, but the area sealed by the oil film also becomes relatively small. This may result in insufficient prevention of leakage of refrigerant gas 181. Furthermore, the ratio L2 / L1 cannot exceed 1.0 (because the seal length (L2) is equal to or less than the total piston length (L1)).

[0139] In the present disclosure, the outer peripheral surface of piston 140 may be a smooth surface without any intentional irregularities, but may have, for example, an annular oil supply groove formed therein. Forming the oil supply groove in the outer peripheral surface of piston 140 makes it possible to supply a sufficient amount of refrigerant oil 180 to the seal area of ​​piston 140, particularly when low-viscosity oil is used as refrigerant oil 180.

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

[0141] If the width of the oil supply groove is less than 0.1 mm, it becomes difficult to supply a sufficient amount of refrigerating oil 180 to the seal area, even if the refrigerating oil 180 is low-viscosity oil. On the other hand, if the width of the oil supply groove exceeds 0.5 mm, if the refrigerating oil 180 is low-viscosity oil, the width of the oil supply groove becomes too wide, causing the refrigerating oil 180 to leak out of the seal area, making it difficult to retain an appropriate amount of refrigerating oil 180 in the seal area.

[0142] Here, for the sake of convenience, when the rotation frequency is controlled to be 16 r / s or more and 35 r / s or less, the configuration for setting the average reciprocating speed of the piston 140 (piston average speed) to exceed 0.31 m / s is abbreviated as a "configuration for increasing the piston average speed (V)", and the configuration for setting the ratio S / D of the reciprocating stroke amount (S) of the piston 140 to the piston diameter (D) within a range of 0.78 to 1.00 is abbreviated as a "configuration for setting the ratio S / D". When the configuration in which the ratio L1 / D of the piston overall length (L1) to the piston diameter (D) is set within the range of 0.8 to 1.0, and the ratio L2 / L1 of the seal length (L2) to the piston overall length (L1) is set within the range of 0.9 to 1.0 is abbreviated as the "configuration for setting the ratio L1 / D and the ratio L2 / L1," 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 can each be applied independently to the refrigerant compressor 100.

[0143] That is, in the refrigerant compressor 100 according to the present disclosure, by applying at least one of a configuration for increasing the piston mean speed (V), a configuration for setting the ratio S / D, and a configuration for setting the ratios L1 / D and L2 / L1, even when a low viscosity oil is used as the refrigeration oil 180, leakage of the refrigerant gas 181 can be effectively suppressed, and an even better coefficient of performance (COP) can be achieved.

[0144] As described above, in the hermetic refrigerant compressor according to the first embodiment, the refrigerating machine oil 180 has a kinematic viscosity of 1.0 mmHg at 40°C. 2 / s~2.5mm 2When using a low viscosity oil in the range of 16 r / s or more and 35 r / s or less, if a controller for controlling the operating frequency of the refrigerant compressor 100 is provided, the average speed at which the piston 140 reciprocates may be set to exceed 0.31 m / s when the controller controls the operating frequency to be 16 r / s or more and 35 r / s or less.

[0145] Alternatively, in the hermetic refrigerant compressor according to the first embodiment, when the low viscosity oil is used as the refrigeration oil, the ratio S / D of the stroke amount (S) of the reciprocating movement of the piston 140 to the piston diameter (D) may be in the range of 0.78 to 1.00.

[0146] Alternatively, in the hermetic refrigerant compressor according to the first embodiment, when the low viscosity oil is used as refrigeration oil 180, the length of the area where piston 140 seals inside compression chamber 133 by its reciprocating motion is defined as sealing length (L2), and the ratio L1 / D of the piston total length (L1) to the piston diameter (D) may be in the range of 0.8 to 1.0, and the ratio L2 / L1 of the sealing length (L2) to the piston total length (L1) may be in the range of 0.9 to 1.0.

[0147] A hermetic refrigerant compressor having these configurations can further reduce leakage of refrigerant gas 181 from between piston 140 and compression chamber 133 when low-viscosity oil is used as refrigeration oil 180. This can further improve the coefficient of performance (COP) of the hermetic refrigerant compressor.

[0148] (Embodiment 2) The hermetic refrigerant compressor according to the second embodiment has the same basic configuration as the hermetic refrigerant compressor according to the first embodiment, but has a more distinctive configuration in the main shaft sliding portion (the sliding portion formed by the main shaft 124 of the crankshaft 120 and the main bearing 134). Note that the basic configuration of the hermetic refrigerant compressor according to the second embodiment is the same as the configuration shown in Fig. 1 in the first embodiment, and therefore detailed description thereof will be omitted.

[0149] [Main shaft sliding part] An example of a specific configuration of the main shaft sliding part in Embodiment 2 will be described in detail with reference to Figures 4A to 4C. Figure 4A is a schematic diagram showing an example of the configuration when the sliding surface of the crankshaft 120 included in the refrigerant compressor 100 shown in Figure 1 is a single surface, and Figures 4B and 4C are schematic diagrams showing an example of the configuration when the sliding surface of the crankshaft 120 is divided into multiple surfaces.

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

[0151] The specific configuration for dividing the sliding surface into multiple sections is not particularly limited, but typically, a recessed portion recessed (concave) toward the central axis from the sliding surface is formed between the multiple sliding surfaces. As shown in FIGS. 1 and 4B, this recessed portion constitutes the non-sliding outer peripheral surface 127. The specific shape of the recessed portion is also not particularly limited, and for example, the depth thereof 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 recessed portion (i.e., the distance between the multiple sliding surfaces) is also not particularly limited, and can be set appropriately depending on the degree to which the width of the sliding surface (sliding area) is narrowed (lowered or reduced).

[0152] When the sliding surface is divided into multiple parts, the number of sliding surfaces is not particularly limited. As shown in FIGS. 1 and 4B, the sliding surface may be divided into two surfaces, a first sliding surface 126a and a second sliding surface 126b. As shown in FIG. 4C, the sliding surface may be divided into three surfaces, a first sliding surface 126c, a second sliding surface 126d, and a third sliding surface 126e. Alternatively, the sliding surface 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, by setting the ratio of the axial length of the sliding surface to the outer diameter (diameter) of the part that becomes the sliding surface in the main shaft sliding part 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, for example, FIG. 4A), the axial length of the sliding surface is defined as the single sliding length T, and when the sliding surface is divided into multiple surfaces (for example, FIG. 4B or FIG. 4C), the axial length of the sliding surface with the shortest axial length is defined as the single sliding length T. Then, when the outer diameter (diameter) of the portion of the shank that becomes the sliding surface is defined as the outer diameter K, the shank is designed so that the ratio T / K of the single sliding length T to the outer diameter K of the shank is 0.51 or less.

[0155] 4A, for convenience 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 is illustrated enlarged relative to the outer diameter K, and if this is as shown in FIG. 4A, the ratio T / K exceeds 0.51. However, in reality, for example, by forming a recess (non-sliding outer peripheral surface) on the upper part (eccentric shaft 122 side) or lower part (refrigerant oil 180 side) of the main shaft 124 when viewed from the single sliding surface 126, it is possible to set the ratio T / K 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", its 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] In FIG. 4B as well, similar to FIG. 4A, for the sake of convenience in explanation, the outer diameter K and the length Ta of the first sliding surface 126a are shown with Ta being larger 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 central second sliding surface 126d 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", its 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. Also, 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~2.5mm 2 / s), sufficient wear resistance cannot be obtained even if a sulfur-based sliding property modifier, which will be described later, is added to the refrigeration oil 180. On the other hand, if the ratio T / K is less than 0.15, the sliding surface may become too narrow, although this depends on the conditions of the shaft. Generally, if the ratio T / K is 0.15 or more, the sliding area is not excessively reduced, and therefore even if a low-viscosity oil is used as the refrigeration oil 180, the sulfur-based sliding property modifier can be used to preferably achieve wear resistance of the main shaft sliding part.

[0161] Alternatively, in the second embodiment, when the sliding surface of the spindle sliding part is divided into multiple surfaces, an axial length other than the single sliding length T described above may be specified, 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. This makes it possible to reduce the sliding area without substantially affecting the wear resistance.

[0162] Specifically, in this second embodiment, when the sliding surface is divided into multiple surfaces, the shaft portion may be designed so that when the sum of the axial lengths of the multiple sliding surfaces is the total sliding length Tt, 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] For convenience, the configuration where the ratio T / K≦0.51 based on the single sliding length T is referred to as the "first configuration of the main shaft sliding portion," 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 portion." Only the first configuration may be combined with the characteristic configuration of embodiment 1, or only the second configuration may be combined with the characteristic configuration of embodiment 1. Alternatively, both the first and second configurations may be combined with the characteristic configuration of embodiment 1.

[0165] Fig. 4A shows an example in which the first configuration is applied to the main shaft sliding portion, and Fig. 4B and Fig. 4C show examples in which both the first configuration and the second configuration are applied to the main shaft sliding portion, but it goes without saying that the present disclosure is not limited to the configurations shown in Fig. 4A to Fig. 4C. As described above, only the second configuration can be applied to the main shaft sliding portion.

[0166] In this way, when there are multiple sliding surfaces, if the ratio T / K is 0.51 or less and the ratio Tt / K is 1.26 or less, low viscosity oil (kinematic viscosity at 40°C is 1.0 mm 2 / s~2.5mm 2 In a state where the sliding area is reduced by using a sulfur-based sliding property modifier (within the range of / s), the wear resistance of the sliding portion of the main shaft can be further improved, which is derived from the sulfur-based sliding property modifier described later.

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

[0168] 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 to this and the same applies to the eccentric shaft 122. In the present second embodiment, as described in the first embodiment, the connecting portion between 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 the "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 multiple surfaces, when the axial length of the sliding surface with the shortest 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 eccentric shaft 122 should be 0.51 or less. Also, when the sum of the axial lengths of the multiple sliding surfaces of the eccentric shaft 122 is defined as a total sliding length Tt, the ratio Tt / K of the total sliding length Tt to the outer diameter K of the eccentric shaft 122 should be 1.26 or less.

[0170] Therefore, in the second embodiment, the refrigerant compressor 100 only needs to satisfy the "first configuration" that the ratio Tt / K is 0.51 or less in at least one of the shafts, that is, the main shaft 124 and the eccentric shaft 122. Alternatively, it only needs to satisfy the "second configuration" that the ratio Tt / K is 1.26 or less in at least one of the main shaft 124 and the eccentric shaft 122. Furthermore, at least one of the main shaft 124 and the eccentric shaft 122 may satisfy both the first and second configurations.

[0171] Therefore, if the sliding part formed by the connecting part of the eccentric shaft 122 and the connecting means 142 is defined as the "eccentric shaft sliding part," then any "main shaft sliding part" in the description of the second embodiment can be replaced with the "eccentric shaft sliding part." Furthermore, when the first or second configuration is applied to the eccentric shaft sliding part, it can also be expressed as the "first configuration of the eccentric shaft sliding part" or the "second configuration of the eccentric shaft sliding part."

[0172] [Sulfur-based friction modifier] The refrigerating machine oil 180 used in the second embodiment is as described in the first embodiment, and has a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2 A more specific configuration of the refrigeration oil 180 in the present disclosure will be described in the embodiment to be described later.

[0173] In the second embodiment, the low-viscosity oil serving as the refrigerating machine oil 180 contains a sulfur-based sliding property improver. 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 iron-based material is not particularly limited, and examples include metal materials containing iron as a main component, such as various known cast irons and steel materials. The sulfur-based sliding property improver may be any material that can react with such an iron-based material and sulfur.

[0174] Therefore, the sliding property improver in this embodiment 2 may be sulfur itself or a sulfur compound that contains sulfur and is capable of reacting with iron-based materials. For example, sulfur compounds that can be used as sliding property improvers include sulfurized olefins, sulfide compounds (e.g., dibenzyl (di)sulfide (DBDS)), xanthates, thiadiazoles, thiocarbonates, sulfurized oils and fats, sulfurized esters, dithiocarbamates, and sulfurized terpenes.

[0175] There are no particular limitations on the content of the sulfur-based sliding property improver in the refrigerating machine oil 180. Typically, the sliding property improver may be added to the refrigerating machine oil 180 so that the content is 100 ppm or more when converted to elemental sulfur weight (mass). The lower limit of the amount (content) of the sliding property improver, which is 100 ppm when converted to elemental sulfur weight, is greater than the upper limit of the general amount of addition of a sulfur-based extreme pressure additive, which will be described later.

[0176] If the content (addition amount) of the sliding property modifier is less than 100 ppm when converted to elemental sulfur weight, depending on various conditions, when a low-viscosity refrigerant oil 180 is used to reduce 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. Furthermore, a preferred lower limit of the content of the sulfur-based sliding property modifier can be, for example, 150 ppm or more when converted to elemental sulfur weight. Furthermore, a preferred upper limit of the content of the sulfur-based sliding property modifier can be, for example, 1000 ppm or less when converted to elemental sulfur weight, and more preferably 500 ppm or less.

[0177] The sulfur-based sliding property modifier used in the present disclosure may be a compound similar to that of a known sulfur-based extreme pressure additive, but it may also be one that is relatively more reactive with the shaft material than known extreme pressure additives, or may be added to the refrigerating machine oil 180 in an amount greater than the typical amount (content) of known extreme pressure additives.

[0178] In general, extreme pressure additives are compounds containing active elements such as sulfur, halogen elements, and phosphorus, which chemically react with the material surfaces (sliding surfaces) that make up the sliding parts to form a coating, which suppresses wear, seizure, fusion, etc. of the sliding members. However, it is also well known that compounds containing sulfur easily react with copper.

[0179] In the refrigerant compressor 100, copper wire is used as the winding of the electric element 104. Furthermore, in a freezing / refrigeration device using the refrigerant compressor 100, copper pipes are generally used as refrigerant piping. As mentioned above, copper is susceptible to corrosion due to reaction with sulfur-containing compounds, and therefore, when a sulfur-based extreme pressure additive is used, measures are required to avoid or suppress corrosion of copper members (or copper-containing members) provided in the refrigerant compressor 100 or the freezing / refrigeration device, and to prevent a decrease in their reliability.

[0180] Therefore, in the field of the refrigerant compressor 100, it is common technical knowledge to use a special compound in combination with the sulfur-based extreme pressure additive to prevent it from reacting with copper or copper-containing components of the refrigerant compressor 100 or the refrigeration / freezing device, or to not use a sulfur-based compound as an additive at all.

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

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

[0183] When the oil film breaks down in the sliding section and metallic contact occurs between the sliding members, the surface layer (e.g., the oxide layer) is removed from the contacting portion of each sliding surface, resulting in the formation of new metallic protrusions. These metallic protrusions on the sliding surfaces may fuse together. The sliding property modifier forms a coating (anti-wear film) in place of the removed surface layer. This prevents the metallic protrusions from fusing together, thereby effectively suppressing wear in the sliding section.

[0184] In contrast, extreme-pressure additives quickly form a film (extreme-pressure film, EP film) to replace the removed surface layer. This EP film is formed more firmly on the sliding surface than the anti-wear film formed by the sliding property modifier. This is because extreme-pressure additives are intended to suppress wear in sliding parts in a lubricated state where the contact pressure between the sliding surfaces is relatively high and the oil film is prone to rupture, i.e., in an "extreme-pressure state."

[0185] Typically, an extreme-pressure additive is added to the refrigerating machine oil 180 to suppress wear in the sliding parts of the refrigerant compressor 100. In contrast, it is not common to add a sliding property improver, which forms a film slower than an extreme-pressure additive. However, in the second embodiment, it is expected that adding a sulfur-based sliding property improver will cause a film to form at a moderate rate on the main shaft sliding part, making it easier for sulfur to localize (be unevenly distributed) on the main shaft sliding part.

[0186] As a result, even if a higher concentration of sulfur-based compound (sulfur-based extreme pressure additive) is added than usual, not only can good sliding properties be achieved in the main shaft sliding part, but it is also thought that corrosion of copper members (or copper-containing members) provided in the refrigerant compressor 100 or the freezing / refrigeration device is suppressed.

[0187] In this way, in the second embodiment, the refrigerating machine oil 180 is a refrigerating machine oil having a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2 In the refrigerant compressor 100 using low-viscosity oil in the range of 1 / s, at least one of the configuration for increasing the average piston speed (V), the configuration for setting the ratio S / D, and the configuration for setting the ratios L1 / D and L2 / L1, as described in the first embodiment, is applied, and further, at least in the main shaft sliding portion, a first configuration in which the ratio T / K of the single sliding length T to the outer diameter K of the shaft portion is 0.51 or less, or a second configuration (or both the first and second configurations) in which the ratio Tt / K of the total sliding length Tt to the outer diameter K of the shaft portion is 1.26 or less, and a configuration in which a sulfur-based sliding property modifier is used is applied.

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

[0189] Moreover, in the present disclosure, if the refrigerant compressor 100 is configured to be inverter-driven, the electric element 104 may be operated at a low rotation speed (low-speed operation) or at a high rotation speed (high-speed operation). In particular, in the present disclosure, the electric element 104 may be operated at a low rotation speed of 16 r / s or more and 35 r / s or less. Generally, during low-speed operation, the oil supply capacity of the oil supply mechanism 125 provided on the crankshaft 120 decreases, and the amount of refrigeration oil 180 supplied to each sliding part 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 and the viscosity of the oil film can be increased. This makes it possible to suppress an increase in sliding loss in the cylinder sliding parts and to suppress leakage of refrigerant gas 181. This allows for a good coefficient of performance (COP).

[0191] On the other hand, by applying the first or second configuration to the main shaft sliding portion, the sliding area between the main shaft 124 and the main bearing 134 becomes relatively small, but good wear resistance can be achieved even if the supply amount of refrigerating machine oil 180 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.

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

[0193] In addition, if both the first and second configurations are applied to the main shaft sliding portion of the refrigerant compressor 100, the lubrication state of the main shaft sliding portion can be further improved, thereby further improving the coefficient of performance (COP).

[0194] (Embodiment 3) The hermetic refrigerant compressor according to the third embodiment has the same basic configuration as the hermetic refrigerant compressor according to the first embodiment, but has a more distinctive thrust bearing configuration. Note that the basic configuration of the hermetic refrigerant compressor according to the third embodiment is the same as the configuration shown in Fig. 1 in the first embodiment, and therefore detailed description thereof will be omitted.

[0195] [Thrust bearing] An example of a specific configuration of the thrust bearing in the second embodiment will be described in detail with reference to Fig. 5 and Fig. 6. Fig. 5 and Fig. 6 each schematically show a portion of a cross section of the refrigerant compressor 100 shown in Fig. 1. Fig. 5 schematically shows an example of distances P and Q set in the thrust bearing provided in the refrigerant compressor 100 and a load (main shaft load) applied to the main shaft sliding portion. Fig. 6 schematically shows an example of the configuration of the main part of the thrust bearing.

[0196] 1, in the refrigerant compressor 100, the main bearing 134 has a tubular or cylindrical shape that extends vertically relative to the main body of the cylinder block 130, which extends in the "lateral direction" within the sealed container 102. The main body of the main bearing 134 extends below the cylinder block 130. As described in the first embodiment, the tubular extension 137 extends above the cylinder block 130. Therefore, the main body of the main bearing 134 and the tubular extension 137 form a single tubular or cylindrical structure.

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

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

[0199] 6, the inner surface of the upper end of the tubular extension 137 may be chamfered or otherwise processed. 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. Note that if the inner surface of the upper end of the tubular extension 137 is not chamfered or otherwise processed, 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] As shown in FIG. 5, when the distance between the axial center 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 axial center 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 the refrigerant compressor 100 is provided with a thrust bearing such as thrust ball bearing 210, when distance P is within the range of 38 mm to 51 mm, distance Q is 16 mm or less.

[0201] In the third embodiment, the refrigerant compressor 100 is provided with a thrust bearing on the thrust surface 136 of the main bearing 134. There are no particular limitations on the specific configuration of the thrust bearing, and any type of rolling bearing may be used. In the third embodiment, however, a thrust ball bearing 210 is used, as shown in Fig. 1, 5 or 6. 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 the lower race 206, and a plurality of balls 204 serving as rolling elements that rollably contact the lower race 206 and the upper race 202. A vibration damping 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] A thrust ball bearing 210 is disposed on the outer periphery of the tubular extension 137, and a 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 disposed parallel to each other. Note that the upper race 202 and the lower race 206 may be provided with arc-shaped grooves.

[0203] 6, the lower race 206, balls 204, and upper race 202 are stacked in this order on top of the thrust surface 136 while in contact with each other, and the flange portion 128 of the crankshaft 120 is seated on the top surface of the upper race 202. This constitutes a thrust ball bearing 210.

[0204] Thrust ball bearing 210 is a rolling bearing in which balls 204 roll in point contact with upper race 202 and lower race 206. Therefore, thrust ball bearing 210 can support a load in the vertical direction while rotating main shaft 124 with little friction. Note that while thrust ball bearing 210 is a "ball bearing" that uses balls 204 as rolling elements, it may also be a "roller bearing" that uses rollers as rolling elements, or may be another rolling bearing.

[0205] As a result, the bearing function of the plain bearing is replaced by a rolling bearing called the thrust ball bearing 210, thereby reducing loss and effectively improving the efficiency of the refrigerant compressor 100. However, normally, providing a thrust bearing such as the thrust ball bearing 210 increases the overall height of the refrigerant compressor 100.

[0206] In contrast, in the refrigerant compressor 100 according to the present disclosure, the distances P and Q based on the axis of the compression chamber 133 are set so that when the distance P is within the range of 38 mm to 51 mm, the distance Q is 16 mm or less.

[0207] Generally, in order to reduce the sliding loss in the main shaft 124, it is possible to adopt a configuration that reduces the friction coefficient in the main shaft sliding portion and / or a configuration that reduces the load (main shaft load F2) on the main shaft 124. Furthermore, in order to reduce the main shaft load F2, it is possible to adopt a configuration that reduces the distance Q and / or a configuration that increases the distance P.

[0208] However, increasing the distance P requires increasing (raising) the overall height of the refrigerant compressor 100. If the overall height is increased in this way, it will be necessary to expand the engine room (machine room) of the refrigeration / freezer unit in which the refrigerant compressor 100 is installed, which will ultimately lead to a reduction in the internal volume of the refrigeration / freezer unit. Therefore, in order to reduce the main shaft load F2, it is expected that the distance Q will be reduced without changing the distance P.

[0209] However, if one were to simply try to reduce the distance Q, one could consider adopting a method of thinning the thickness of the support portion of the cylinder block 130 or thinning the thickness of the flange portion 128 to 4 mm or less, i.e., a method of thinning a specific component (or part of it) (thinning method).

[0210] However, adopting such a thinning method results in deformation of other components. Specifically, thinning the support portion reduces the rigidity of the cylinder block 130, making the main bearing 134 more susceptible to deformation, and thinning the flange portion 128 increases the tilt of the eccentric shaft 122. In particular, the increase in tilt of the eccentric shaft 122 due to thinning the flange portion 128 was not anticipated in the past.

[0211] In this way, when the distance Q is reduced by the thinning method, the efficiency of the refrigerant compressor 100 can be increased, but there is a risk that the reliability of the refrigerant compressor 100 may be reduced due to deformation of certain members.

[0212] In contrast to this, in the present third embodiment, as a result of experimental verification, it has been independently discovered that by setting the upper limit of the distance Q to a predetermined value, i.e., 16 mm or less, it is possible to achieve both high efficiency and good reliability without employing a thinning technique.

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

[0214] In the third embodiment, 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 a lower limit value). Therefore, there is no need to increase (increase) the overall height of the refrigerant compressor 100. This not only makes it possible to achieve high efficiency while maintaining the good quality (especially reliability) of the refrigerant compressor 100, but also makes it unnecessary to expand the engine room (machine room) of the refrigeration / freezer apparatus, thereby ensuring a sufficient internal volume of the refrigeration / freezer apparatus.

[0215] As described above, in the third embodiment, in the refrigerant compressor 100 equipped with a thrust bearing, when the distance P that affects the overall height is set 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 set to 16 mm. This makes it possible to avoid an increase in the overall height without excessively thinning the flange portion 128 that contributes to the stability of the eccentric shaft 122, and also reduces the load on the main shaft 124 without applying any special treatment to the sliding surface.

[0216] As a result, it is possible to achieve even higher efficiency without increasing the overall height of the refrigerant compressor 100. Moreover, since the flange portion 128 is not made excessively thin, it is possible to achieve high efficiency as well as good reliability.

[0217] Here, in order to reduce the sliding loss of the main shaft sliding part, it is possible to reduce the coefficient of friction of the main shaft sliding part in addition to the configuration of reducing the distance Q. To simply reduce the coefficient of friction, it is conceivable to reduce the viscosity of the refrigerating machine oil 180 as much as possible.

[0218] In the refrigerant compressor 100 according to the present disclosure, as described in the first embodiment, the refrigerating machine oil 180 is a refrigerating machine oil having a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2 / s. Therefore, the friction coefficient can be reduced simply by using this low-viscosity oil as the refrigerant oil 180. Furthermore, as will be described in the third embodiment, the main shaft load F2 can be further reduced by setting the distance Q of the refrigerant compressor 100 to 16 mm or less. This reduces the sliding loss of the main shaft sliding portion.

[0219] Therefore, by combining the configuration described in the third embodiment with the configuration described in the first embodiment, it is possible to achieve high efficiency and good reliability not only in the cylinder sliding portion but also in the main shaft sliding portion of the refrigerant compressor 100. This makes it possible to further improve the coefficient of performance (COP) of the refrigerant compressor 100.

[0220] Furthermore, in the third embodiment, there is no need to particularly limit the diameter of piston 140, i.e., piston diameter (D), or the inner diameter of compression chamber 133 into which piston 140 is inserted. If distance Q is set to 16 mm or less when distance P is within the range of 38 mm to 51 mm, not only is there no need to make flange portion 128 excessively thin, but there is also no need to substantially specify piston diameter (D) or the inner diameter of compression chamber 133.

[0221] As explained in the first embodiment, 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 in the cylinder sliding portion can be increased (see the above formula (1)). Setting this ratio S / D leads to a reduction in the piston diameter (D), but in the third embodiment, the piston diameter (D) does not need to be substantially specified. Therefore, the configuration explained in the third embodiment has the advantage that it can be easily applied to the configuration explained in the first embodiment.

[0222] Furthermore, according to the third embodiment, by setting the distance Q to 16 mm or less, the spindle load F2 is reduced, which makes it easier to form a good oil film during low-speed operation even when low-viscosity oil is used as the refrigeration oil 180. As described in the first embodiment, in particular in the present disclosure, low-speed operation with an operating frequency of 16 r / s or more and 35 r / s or less may be performed.

[0223] Therefore, when the configuration described in the third embodiment is applied to the configuration described in the first embodiment, it can be fully applied even during low-speed operation, thereby making it possible to effectively suppress or avoid wear or seizure at the sliding portion of the main shaft. Therefore, even when the refrigerant compressor 100 is operating at low speed, the configuration described in the third embodiment can be easily applied to the configuration described in the first embodiment.

[0224] Furthermore, as described in the second embodiment, by combining the configuration described in the first embodiment with the configuration described in the second embodiment, it is possible to achieve an even better coefficient of performance (COP) in the refrigerant compressor 100. Furthermore, by combining the configuration described in the third embodiment with the configuration described in the first embodiment, it is possible to achieve an even better coefficient of performance (COP). Therefore, by combining the configurations described in the first embodiment, the second embodiment, and the third embodiment, it is possible to achieve a favorable synergistic effect in terms of the effect of achieving a good coefficient of performance (COP).

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

[0226] For example, although not shown, the 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 are located at the lower part of 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] 1, in the third embodiment, the crankshaft 120 extends in the "vertical direction" (up-down direction) of the refrigerant compressor 100, and therefore the main shaft 124 and the eccentric shaft 122 also extend in the vertical 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 "horizontal direction" (direction perpendicular to the vertical direction), and the piston 140 and the compression chamber 133 may be located in one of the horizontal directions rather than the vertical direction within the refrigerant compressor 100. In this case, both ends of the sliding surfaces that serve as the basis for the distances P and Q are located in the horizontal direction, not in the vertical direction.

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

[0229] Furthermore, the refrigeration oil 180 used in the third embodiment may be the low-viscosity oil described above, but as will be described in the fourth embodiment below, the low-viscosity oil may contain a high-molecular-weight component (a preferred oil described below). Such a preferred oil allows for the formation of a better oil film in the sliding parts. This further improves the effects obtained by the configuration described in the third embodiment, as well as the effects obtained by the configuration described in the first embodiment (and also the effects when the configuration described in the second embodiment is applied).

[0230] (Fourth embodiment) The hermetic refrigerant compressor according to the fourth embodiment has the same basic configuration as at least one of the hermetic refrigerant compressors according to the first to third embodiments described above, but has a further distinctive feature in the low viscosity oil used as refrigerating machine oil 180. Note that in the fourth embodiment, a specific configuration example of refrigerating machine oil 180 applicable to the refrigerant compressor 100 described in any of the first to third embodiments will be described. Therefore, a specific description of the refrigerant compressor 100 will be omitted.

[0231] As described above, the refrigeration oil 180 according to the present disclosure has a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2 There are no particular limitations on the refrigeration oil 180, as long as it is a low-viscosity oil within the range of 1 / s. A typical example of the refrigeration oil 180 is at least one oily substance selected from the group consisting of mineral oil, alkylbenzene oil, and ester oil. As mentioned above, a typical example of the oily substance is mineral oil.

[0232] These oily substances may be used alone or in appropriate combination of two or more. The combination of two or more oily substances here includes not only a combination of two or more different oily substances that fall under the category of mineral oil, but also a combination of one or more oily substances that fall under the category of mineral oil with one or more oily substances that fall under the category of alkylbenzene oil (or one or more oily substances that fall under the category of ester oil).

[0233] The refrigerating machine oil 180 according to the present disclosure may contain various known additives in addition to the oily substance described above. As such additives, various additives known in the field of refrigerating machine oil 180 can be suitably used, and representative examples include a sliding property improver, an extreme pressure additive, an oiliness agent, an antioxidant, an acid scavenger, a metal deactivator, an antifoaming agent, a corrosion inhibitor, and a dispersant.

[0234] In particular, in the second embodiment, a sulfur-based sliding property improver is added to the low-viscosity oil used as refrigeration oil 180, but a known extreme-pressure additive may also be added. Specific extreme-pressure additives that can be suitably used include, but are not limited to, known compounds such as phosphorus-based compounds such as phosphate esters, and halogenated compounds such as chlorinated hydrocarbons or fluorinated hydrocarbons. Only one type of these extreme-pressure additives may be added to the low-viscosity oil (oily substance), or two or more types may be added in appropriate combination.

[0235] Among these extreme pressure additives, phosphorus-based compounds can be preferably used. Typical phosphorus-based compounds include tricresyl phosphate (TCP), tributyl phosphate (TBP), and triphenyl phosphate (TPP), with TCP being more preferably used. In particular, in the configuration described in the second embodiment, by adding a phosphorus-based extreme pressure additive to the refrigerant oil 180 in addition to a sulfur-based sliding property improver, it is possible to achieve favorable wear reduction in the sliding parts of the main shaft.

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

[0237] It should be noted that a sliding property improver, an extreme pressure additive, or other additives may be added to the refrigeration oil 180 used in the configurations 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 interfere with the effects obtained by the configurations described in the first to third embodiments and that allows the effects derived from the additives to be obtained.

[0238] In other words, the refrigerating machine oil 180 used in the refrigerant compressor 100 according to the present disclosure has a kinematic viscosity of 1.0 mm at 40°C.2 / s~2.5mm 2 / s. When two or more types of oily substances are used to form the "oil composition," the oil composition only needs to have a kinematic viscosity at 40°C within the above-mentioned range. Furthermore, refrigeration oil 180 according to the present disclosure may be an "oil composition" that contains, in addition to one or more types of oily substances, a sulfur-based sliding property improver (or other sliding property improver), a phosphorus-based extreme pressure additive (or other extreme pressure additive), or other additives.

[0239] Therefore, in the present disclosure, the oil composition used as the refrigeration oil 180 has a kinematic viscosity of 1.0 mm at 40°C. 2 / s~2.5mm 2 It can be said to be a "low viscosity oil" that is in the range of / s.

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

[0241] Furthermore, the polydispersity index (PDI) of the oily substance, i.e., the ratio of number average molecular weight Mn to weight average molecular weight Mw, Mw / Mn, may be within the range of 1.0 to 1.1. Note that the method for measuring the oily substance and the molecular weight (number average molecular weight Mn and weight average molecular weight Mw) described below is not particularly limited, but in the present disclosure, a method using standard polystyrene equivalents according to GPC (Gel Permeation Chromatography) can be used.

[0242] Generally, when the viscosity of an oily substance used as the refrigeration oil 180 is reduced, the molecules of the oily substance are reduced in molecular weight. When such a low-molecular-weight oily substance comes into contact with a resin material present inside the refrigerant compressor 100, there is a concern that the oily substance may "deteriorate extractability," in which components (extractable components) contained in the resin material may be more easily extracted.

[0243] In contrast, if the polydispersity Mw / Mn of the oily substance is at least within the range of 1.0 to 1.1, the variation in the molecular weight of the oily substance is reduced, and the molecular weight of the oily substance is prevented from becoming excessively small. Therefore, it is possible to significantly reduce the "deterioration of extractability" of the refrigerating machine oil 180, i.e., the possibility that the refrigerating machine oil 180 extracts extractable components from the resin material used in the refrigerant compressor 100.

[0244] The "deterioration of extractability" in refrigeration oil 180 may result in the low-viscosity oil used as refrigeration oil 180 being contaminated with extractable components extracted from the resin material, which may result in a deterioration in the quality of refrigeration oil 180. A deterioration in the quality of refrigeration oil 180 may not only result in insufficient lubrication of the cylinder sliding parts or the main shaft sliding parts, but may also result in an inability to form an adequate oil film on the cylinder sliding parts. In this case, leakage of refrigerant gas 181 from between piston 140 and cylinder 132 may not be effectively suppressed. Therefore, the molecular weight and polydispersity of the low-viscosity oil used as refrigeration oil 180 (its main component, the oily substance) may be within the above-mentioned ranges.

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

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

[0247] The high molecular weight component contained in the suitable oil may have a weight average molecular weight Mw (mass average molecular weight) of at least 500. The content of the high molecular weight component may be at least 0.5% by mass when the total mass of the oil composition used as the refrigeration oil 180 is taken as 100% by mass.

[0248] The suitable oil used as refrigeration oil 180 in the fourth embodiment may be one that originally contains high molecular weight components, or may be one to which an oily substance corresponding to the high molecular weight components is added so that the content is 0.5% by mass or more. An example of the former is mineral oil. When preparing (producing) the suitable oil by refining unrefined or roughly refined raw mineral oil, the refining conditions or refining method for the raw oil may be adjusted so that 0.5% by mass or more of the high molecular weight components remain. An example of the latter is one in which mineral oil, alkylbenzene oil, or polyalkylene glycol oil is used as the "main component" of the suitable oil, and an oily substance that becomes the high molecular weight component is added to this main component as an "additive component."

[0249] The molecular weight and polydispersity of the oily substance that is the main component of the suitable oil may be within the ranges described above. If the molecular weight and polydispersity of the suitable oil are within these ranges, and the oil contains 0.5 mass% or more of a high molecular weight component, a suitable oil film can be formed in the sliding portion of the main shaft, particularly when the distance Q is set to 16 mm or less in the thrust bearing configuration described in the third embodiment.

[0250] The upper limit of the content of the high molecular weight component is not particularly limited as long as it does not affect the function or effect of the preferred oil, but typical examples of the upper limit of the content of the high molecular weight component include 7.0% by mass or less, 6.0% by mass or less, and 5.0% by mass.

[0251] Although it depends 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 high molecular weight components exceeds 7.0 mass %, it may affect the viscosity of the oil (oil composition) used as the refrigeration oil 180. In this case, if the kinematic viscosity of the oil (oil composition) at 40°C is 1.0 mm 2 / s~2.5mm 2 / s range, which means that the coefficient of performance (COP) improvement effect commensurate with the content of high molecular weight components may not be obtained.

[0252] In addition, the reason why the coefficient of performance (COP) of the refrigerant compressor 100 is improved by the preferred oil containing a high molecular weight component is that the preferred oil has a low viscosity (kinematic viscosity at 40°C is 1.0 mmHg). 2 / s~2.5mm 2 / s), the high molecular weight components contribute to the formation of a good oil film in the sliding parts. Therefore, when a suitable oil containing high molecular weight components is used as refrigeration oil 180, it is thought that an even better oil film is formed not only in the main shaft sliding parts but also in the cylinder sliding parts. Therefore, not only can good lubrication be achieved in these sliding parts, but leakage of refrigerant gas 181 from the cylinder sliding parts can also be expected to be further suppressed.

[0253] When the suitable oil is a main component to which a high-molecular-weight component has been added, the specific material or type of the high-molecular-weight component is not particularly limited, as long as it is an oily substance with a weight-average molecular weight Mw of 500 or more. For example, when the main component is mineral oil, the high-molecular-weight component may be the same mineral oil, alkylbenzene oil, polyalkylene glycol oil, or another oily substance.

[0254] Furthermore, when the suitable oil is an oily substance as the main component to which a high-molecular-weight component has been added (oil composition), 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 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 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 as the high-molecular-weight component. Alternatively, two or more types of mixtures of oily substances in which a high-molecular-weight component has been added to a main component may be further mixed.

[0255] As described above, the refrigeration oil 180 according to the fourth embodiment may contain one or more oily substances as the main component, together with a sliding property improver (e.g., sulfur or a sulfur-containing compound), an extreme-pressure additive (e.g., a phosphorus-containing compound), or other known additives. When a suitable oil containing a high-molecular-weight component is used as the refrigeration oil 180, an oiliness agent may be added as an additive. By including an oiliness agent in the suitable oil, an oil film formed by the suitable oil is more easily formed on the sliding surfaces of the sliding parts. This can more effectively reduce friction in the sliding parts, and can also suppress leakage of the refrigerant gas 181 from the cylinder sliding parts.

[0256] The specific type of oily agent is not particularly limited, but representative examples include higher fatty acids, higher alcohols, esters (ester compounds), ethers, amines, amides, metal soaps, etc. These oily agents may be used alone or in combination of two or more. The amount of oily agent added is not particularly limited, but can be, for example, in the range of 0.01 to 1% by mass, where the total mass of the suitable oil (oil composition) is 100% by mass.

[0257] Among the above-mentioned oily agents, particularly representative ones include ester compounds. The ester compounds may be any compounds having an ester structure obtained by reacting an alcohol with a carboxylic acid. The alcohol may be a monohydric alcohol or a polyhydric alcohol having two or more carboxylic acids. Similarly, the carboxylic acid may be a monocarboxylic acid, a dicarboxylic acid, or a tricarboxylic acid (which may have four or more carboxy groups). Generally, commercially available ester oily agents can be suitably used.

[0258] If the suitable oil is an oil composition containing an oiliness agent, the oil film forming ability can be further improved. That is, since the suitable oil contains high molecular weight components, the high molecular weight components are present on the sliding surfaces of the sliding parts (spindle sliding parts, cylinder sliding parts, etc.), which is thought to enable the formation of a good oil film. Furthermore, if the suitable oil contains an oiliness agent, the oiliness agent is adsorbed on the sliding surfaces, which is thought to further facilitate the formation of an oil film by the suitable oil (oil composition).

[0259] In particular, if the oiliness agent is an ester compound, the oiliness agent will have an ester bond. Therefore, the polarity resulting from this ester bond makes it easier for the oil film of the suitable oil (oil composition) to adhere to the sliding parts (improving the adhesion of the oil film). This further improves the oil film forming ability of the suitable oil, thereby further reducing the friction coefficient and more effectively achieving low friction in the sliding parts. Furthermore, in the cylinder sliding parts, a good oil film is more easily formed between the piston 140 and the cylinder 132, which more effectively suppresses leakage of the refrigerant gas 181.

[0260] In addition, when the refrigeration oil 180 according to the fourth embodiment is the aforementioned suitable oil, it may contain a sulfur-based sliding property improver or a phosphorus-based extreme pressure additive as an additive, as described above. By containing these additives in the suitable oil, not only can the effects obtained from each additive be imparted to the suitable oil, but a synergistic effect of each additive can also be expected, thereby further improving the sliding performance of each sliding part and effectively suppressing leakage of the refrigerant gas 181 from the cylinder sliding part.

[0261] On the other hand, the suitable oil may not contain at least one or all of the sulfur-based sliding property improver, phosphorus-based extreme pressure additive, and ester-based oiliness agent, depending on the specific configuration or conditions of the refrigerant compressor 100. In other words, the suitable oil may contain suitable additives as needed, and the specific additives are not limited to the sulfur-based sliding property improver, phosphorus-based extreme pressure additive, ester-based oiliness agent, etc. Also, a low-viscosity oil that does not contain high-molecular-weight components may be used as the refrigerating machine oil 180.

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

[0263] The refrigerant compressor 100 according to the present disclosure can be widely and suitably used in various devices (freezing and refrigeration devices) having a refrigeration cycle or a configuration substantially equivalent thereto. Specific examples include, but are not limited to, refrigerators (household refrigerators and commercial refrigerators), ice makers, showcases, dehumidifiers, heat pump water heaters, heat pump washer-dryers, vending machines, air conditioners, and air compressors. In this second embodiment, the basic configuration of a freezing and refrigeration device will be described using an article storage device shown in FIG. 7 as an application example of the refrigerant compressor 100 according to the present disclosure.

[0264] As shown in Fig. 7, the refrigeration / freezing device according to the fifth embodiment includes a main body 301, a partition wall 304, a refrigerant circuit 305, and the like. The main body 301 is composed of a heat-insulating box and a door, and the box has one side open, and the door opens and closes the opening of the box. The interior of the main body 301 is partitioned by the partition wall 304 into an item storage space 302 and a machine room 303. A blower (not shown) is provided in the storage space 302. The interior 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 the above embodiments, a radiator 307, a pressure reducing device 308, and a heat absorber 309, which are connected in a ring shape by piping. In other words, 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, refrigerant compressor 100 (sealed container 102) is filled with refrigerant gas 181, such as R600a, at a relatively low temperature so that the pressure is equivalent to that of the low-pressure side of the freezing / refrigeration device. Although the specific type of refrigerant gas 181 is not particularly limited, a hydrocarbon gas with a low global warming potential, such as R600a, can be preferably used.

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

[0268] As described above, the freezing / refrigeration device according to the fifth embodiment is equipped with the refrigerant compressor 100 according to any one of the first to fourth embodiments. The refrigerant compressor 100 uses refrigerating machine oil 180 having a kinematic viscosity of 1.0 mmHg at 40°C. 2 / s~2.5mm 2 When a low viscosity oil in the range of 1 / s is used, the coefficient of performance (COP) can be further improved. Therefore, a freezing / refrigeration device equipped with such a refrigerant compressor 100 can reduce its power consumption. [Example]

[0269] The present invention will be explained in more detail 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 conventional refrigerant compressors, a total of four types of mineral oil (1.8 mmHg) with different kinematic viscosities at 40°C were used. 2 / s, 2.5mm 2 / s, 3.3mm 2 / s, and 5.0 mm 2 The amount of refrigerant gas 181 leaking from between piston 140 and cylinder 132 (amount of refrigerant leakage) was evaluated when the operating frequency was set to 17 r / s using refrigerant oil 180 (by changing the kinematic viscosity of refrigerant oil 180). The results are shown in the graph of FIG.

[0271] The refrigerant leakage rate in the reference example was measured (evaluated) as follows. A target refrigerant compressor (see FIG. 1) was modified to block the suction port (not shown in FIG. 1), and a container (refrigerant container) containing a certain amount of refrigerant gas 181 was connected to the discharge port (not shown in FIG. 1) to prepare a refrigerant leakage rate measurement system. Because the suction port was blocked in this measurement system, refrigerant gas 181 was introduced from the refrigerant container through the space between piston 140 and cylinder 132 and into the hermetic refrigerant compressor. Therefore, in this measurement system, the pressure decrease in the refrigerant container can be regarded as the refrigerant leakage rate. Using this measurement system, the refrigerant compressor was operated at various frequencies to evaluate the refrigerant leakage rate when four types of mineral oil with different kinetic viscosities were used.

[0272] In the graph of Figure 8, the horizontal axis represents the kinematic viscosity of Refrigerant Oil 180 at 40°C (unit: mm 2 / s), and the vertical axis is the refrigerant leakage amount (unit: %). The evaluation standard for the refrigerant leakage amount in Figure 8 is a kinematic viscosity of 5.0 mm at 40°C. 2 The result when 180 refrigeration oil was used at 1 / s was taken as 100%.

[0273] As is clear from the results in FIG. 8, in the conventional refrigerant compressor, the amount of refrigerant leakage clearly increases as the viscosity decreases, particularly during low-speed operation (17 r / s).

[0274] (Evaluation method for coefficient of performance) From the results of the reference example, in the conventional refrigerant compressor, the kinematic viscosity at 40°C is 2.5mm during low-speed operation. 2 / s or less, the amount of refrigerant leakage increases significantly. Therefore, we evaluated how the coefficient of performance (COP) changes in the refrigerant compressor 100 to which the configuration for increasing the average piston 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 first embodiment are applied. The above configurations applied to the refrigerant compressor 100 are shown in Table 1.

[0275] [Table 1]

[0276] The coefficient of performance (COP) of the refrigerant compressor 100 of the embodiment or the conventional refrigerant compressor was calculated as the ratio of refrigeration capacity to energy consumption (input) (refrigeration capacity / input). The evaluation standard for the coefficient of performance (COP) was a kinetic viscosity of 5.0 mmHg at 40°C. 2 The result when 180 refrigeration oil was used at 1 / s was taken as 100%.

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

[0278] 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 example are indicated by circle symbols. In both graphs, the horizontal axis represents the kinematic viscosity (unit: mm 2 / s), and the vertical axis is the coefficient of performance (COP).

[0279] (Conventional example) A conventional refrigerant compressor, i.e., 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 oil (1.8 mmHg) with different kinematic viscosities at 40°C were used. 2 / s, 2.3mm 2 / s, 2.7mm 2 / s, 3.3mm 2 / s, and 5.0 mm 2The coefficient of performance (COP) was evaluated using a refrigerating machine oil 180 with a kinematic viscosity of 27 r / s (varied kinetic viscosity of the refrigerating machine oil 180). 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 FIGS. 9 and 10, the results of the conventional example are indicated by a cross symbol.

[0280] (Comparison between Example and Conventional Example) 9, when the operating frequency is 27 r / s, in both the embodiment and the conventional example, the coefficient of performance (COP) improves when the kinematic viscosity of the refrigerating machine oil 180 is reduced. This is because the input power to the refrigerant compressor is reduced as the viscous resistance of the refrigerating machine oil 180 is reduced.

[0281] In contrast, as shown in FIG. 10, when the operating frequency is lower at 17 r / s (during low-speed operation), in the conventional example, the kinematic viscosity (40°C) of the refrigerating machine oil 180 is 2.5 mm 2 / s or less, the coefficient of performance (COP) decreases. This is because, as mentioned above, the kinematic viscosity of Refrigerant Oil 180 is 2.5 mm 2 / s or less, the amount of refrigerant gas 181 leaking from between the piston 140 and the cylinder 132 increases, resulting in a decrease in refrigeration capacity.

[0282] On the other hand, in the embodiment, the kinematic viscosity (40°C) of the refrigerating machine oil 180 is 2.5 mm 2 / s or less, the coefficient of performance (COP) is improved. 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, the refrigerating machine oil 180 is used, which has a kinematic viscosity (40°C) of 1.0 mm 2 / s~2.5mm 2 It can be seen that when a low viscosity oil in the range of / s is used, a good coefficient of performance (COP) can be achieved even during low-speed operation.

[0283] Furthermore, 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 example is 0.34 m / s at 17 r / s. As described above, in the example, a good coefficient of performance (COP) can be achieved even when low-viscosity oil is used as the refrigerating machine oil 180, but in the conventional example, a good coefficient of performance (COP) cannot be achieved when low-viscosity oil is used as the refrigerating machine oil 180. Therefore, it can be seen that a good coefficient of performance (COP) can be achieved as long as the average piston speed exceeds at least 0.31 m / s within the range of 16 r / s to 35 r / s, which is defined as the low-speed operating frequency in the present disclosure.

[0284] (Addendum) Based on the description of the above embodiments, the following techniques are disclosed in this specification.

[0285] (Technology 1) A sealed container and a liquid having a kinematic viscosity of 1.0 mm at 40°C stored in the sealed container 2 / s~2.5mm 2 a cylinder block housed in the sealed container and forming a compression chamber; and a piston inserted in the compression chamber so as to be able to reciprocate, wherein the average reciprocating speed of the piston is set to exceed 0.31 m / s when the operating frequency is 16 r / s or more and 35 r / s or less.

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

[0287] (Technology 3) The hermetic refrigerant compressor according to Technology 1 or Technology 2, wherein, when the length of an area where the piston seals the inside of the compression chamber by its reciprocating motion is defined as a sealing 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, and a ratio L2 / L1 of the sealing length (L2) to the piston overall length (L1) is within a range of 0.9 to 1.0.

[0288] (Technology 4) A sealed container and a liquid having a kinematic viscosity of 1.0 mm at 40°C stored in the sealed container 2 / s~2.5mm 2 / s, a cylinder block housed in the sealed container and forming a compression chamber, and a piston inserted into the compression chamber so as to be able to reciprocate, wherein the ratio S / D of the reciprocating stroke amount (S) of the piston to the piston diameter (D) is within the range of 0.78 to 1.00.

[0289] (Technology 5) The hermetic refrigerant compressor according to claim 4, wherein, when the length of an area where the piston seals the inside of the compression chamber by its reciprocating motion is defined as a sealing length (L2), a ratio L2 / L1 of the sealing length (L2) to the total piston length (L1) is within a range of 0.9 to 1.0.

[0290] (Technology 6) A sealed container and a liquid having a kinematic viscosity of 1.0 mm at 40°C stored in the sealed container 2 / s~2.5mm 2 / s, a cylinder block that is accommodated in the sealed container and forms a compression chamber, and a piston that is inserted into the compression chamber so as to be able to reciprocate, wherein 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, and when the length of an area where the piston seals the inside of the compression chamber by its reciprocating motion is defined as a seal length (L2), 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.

[0291] (Technology 7) The compression element includes, as a shaft portion, a crankshaft having a main shaft and an eccentric shaft, and, as bearing portions supporting the shaft portion, a main bearing supporting the main shaft and an eccentric bearing supporting the eccentric shaft, wherein a sliding surface of the main shaft with the main bearing is divided into a plurality of surfaces, and when a sum of axial lengths of the plurality of sliding surfaces is 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.

[0292] (Technology 8) The compression element includes, as a shaft portion, a crankshaft having a main shaft and an eccentric shaft, and, as bearing portions supporting the shaft portion, a main bearing supporting the main shaft and an eccentric bearing supporting the eccentric shaft, wherein a sliding surface of the main shaft with the main bearing is a single surface or is divided into multiple surfaces, and 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 multiple surfaces, the axial length of a sliding surface having a 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 main shaft is 0.51 or less, and further, the refrigerating machine oil contains sulfur or a compound containing sulfur as a sliding property improver.

[0293] (Technology 9) The compression element further includes a crankshaft having a main shaft and an eccentric shaft, a main bearing supporting the main shaft, and a thrust bearing provided on a thrust surface of the main bearing, wherein an end of a sliding surface of the main bearing on the compression chamber side is a first end and an end on the opposite side is a second end, a distance between an axis of the compression chamber and the second end of the sliding surface of the main bearing is P, and a distance between the axis of the compression chamber and the first end of the sliding surface of the main bearing is Q, and when the distance P is within a range of 38 mm to 51 mm, the distance Q is 16 mm or less.

[0294] (Technology 10) A sealed container and a liquid having a kinematic viscosity of 1.0 mm at 40°C stored in the sealed container 2 / s~2.5mm 2 a cylinder block housed in the sealed container and forming a compression chamber; and a piston inserted and reciprocatable within the compression chamber, wherein the average reciprocating speed of the piston exceeds 0.31 m / s when the operating frequency is 16 r / s or more and 35 r / s or less.

[0295] (Technology 11) A freezing / refrigeration device comprising a refrigerant circuit including the hermetic refrigerant compressor according to any one of Technology 1 to Technology 9 or the hermetic refrigerant compressor for which the operating method according to Technology 9 is performed, a radiator, a pressure reducing device, and a heat absorber, and these are connected in a ring shape by piping.

[0296] The present invention is not limited to the description of the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments or multiple modified examples are also included in the technical scope of the present invention.

[0297] Furthermore, many modifications and other embodiments of the present invention will be apparent to those skilled in the art from the above description. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function thereof can be substantially changed without departing from the spirit of the present invention. [Industrial Applicability]

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

[0299] 100: Hermetic refrigerant compressor 102: Airtight 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 part 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: Connection means 150: Stator 152: Rotor 180: Refrigerating machine oil 181: Refrigerant gas 190: Suspension spring 202: Upper lace 204: Ball (rolling element) 205: Retainer 206: Lower lace 210: Thrust ball bearing (thrust bearing) 240: Conventional piston 301:Main body 302: Storage space 303: Machine room 304: Compartment wall 305: Refrigerant circuit 307: Heat sink 308: Pressure reducing device 309: Heat absorber

Claims

1. A sealed container and The kinematic viscosity at 40°C stored in the sealed container is 1.0 mm 2 / s ~ 2.5 mm 2 / s range of refrigeration oil, a cylinder block housed in the sealed container and forming a compression chamber; and a piston inserted into the compression chamber so as to be able to reciprocate, 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, The ratio S / D of the reciprocating stroke amount (S) of the piston to the piston diameter (D) is in the range of 0.78 to 1.

00. Hermetic refrigerant compressor.

2. A sealed container and The kinematic viscosity at 40°C stored in the sealed container is 1.0 mm 2 / s ~ 2.5 mm 2 / s range of refrigeration oil, a cylinder block housed in the sealed container and forming a compression chamber; and a piston inserted into the compression chamber so as to be able to reciprocate, 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, 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), The ratio L1 / D of the piston overall length (L1) to the piston diameter (D) is in the range of 0.8 to 1.0, The ratio L2 / L1 of the seal length (L2) to the piston overall length (L1) is in the range of 0.9 to 1.

0. Hermetic refrigerant compressor.

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

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

5. A sealed container and The kinematic viscosity at 40°C stored in the sealed container is 1.0 mm 2 / s ~ 2.5 mm 2 / s range of refrigeration oil, a cylinder block housed in the sealed container and forming a compression chamber; and a piston inserted into the compression chamber so as to be able to reciprocate, A hermetic refrigerant compressor, wherein a ratio S / D of a stroke amount (S) of the piston to a piston diameter (D) is in the 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 of the reciprocating motion of the piston exceeds 0.31 m / s. How to operate a hermetic refrigerant compressor.

6. A sealed container and The kinematic viscosity at 40°C stored in the sealed container is 1.0 mm 2 / s ~ 2.5 mm 2 / s range of refrigeration oil, a cylinder block housed in the sealed container and forming a compression chamber; and a piston inserted into the compression chamber so as to be able to reciprocate, 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, 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), The ratio L1 / D of the piston overall length (L1) to the piston diameter (D) is in the range of 0.8 to 1.0, A hermetic refrigerant compressor, wherein the ratio L2 / L1 of the seal length (L2) to the piston overall length (L1) is in the 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 of the reciprocating motion of the piston exceeds 0.31 m / s. How to operate 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 absorber, and these are connected in a ring shape by piping. Refrigeration and freezing equipment.

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