Hermetic refrigerant compressor and refrigeration equipment using the same

Abstract

The hermetic refrigerant compressor (100) contains a refrigerant having a kinematic viscosity of 1 to 9 mmHg at 40°C in a hermetic container (101). 2 The lubricating oil (103) is a lubricating oil having a viscosity of 1000 psi / S and contains sulfur or a compound containing sulfur as a sliding property improver. The compression element (107) includes a crankshaft (108) as a shaft. When the sliding surface of the main shaft (109) is a single surface, the axial length of the sliding surface is defined as a single sliding length L. When the sliding surface is divided into multiple surfaces, the single sliding length L is defined as the shortest axial length of the sliding surface. The ratio L / D of the single sliding length L to the outer diameter D of the main shaft (109) is 0.51 or less. Furthermore, when the sum of the axial lengths of the multiple sliding surfaces is defined as a total sliding length Lt, the ratio Lt / D of the total sliding length Lt to the outer diameter D may be 1.26 or less.

Description

[Technical Field]

[0001] The present invention relates to a hermetic refrigerant compressor used in refrigerators, air conditioners, etc., and to a freezing / refrigerating device using the same. [Background technology]

[0002] In recent years, efforts have been made to develop highly efficient hermetic refrigerant compressors that reduce the use of fossil fuels in order to protect the global environment. For example, in order to achieve high efficiency, it has been proposed to form various coatings on the sliding surfaces of sliding members included in hermetic refrigerant compressors and to use lubricating oils with lower viscosities.

[0003] A hermetic refrigerant compressor contains lubricating oil in a sealed container and houses an electric element and a compression element. The compression element includes sliding members such as a crankshaft, pistons, and connecting rods, and the crankshaft main shaft and main bearing, piston and bore, piston pin and connecting rod, and crankshaft eccentric shaft and connecting rod all form sliding parts.

[0004] For example, Patent Document 1 discloses a configuration in which, in a reciprocating compressor (sealed refrigerant compressor) using low-viscosity lubricating oil, the piston and connecting rod among the sliding members are made of iron-based sintered material, and then subjected to steam treatment, and the steam layer on the surface of the piston is removed by cutting, and the connecting rod is subjected to nitriding treatment after the steam treatment. The lubricating oil used in a reciprocating compressor of this configuration has a kinematic viscosity of 3 mm at 40°C. 2 / S~10mm 2 Items within the / S range are listed.

[0005] When lubricating oil has low viscosity, it is difficult to form an oil film, but in the hermetic refrigerant compressor disclosed in Patent Document 1, the surfaces of the sliding members that make up the sliding parts are specially treated, which prevents wear and seizure of the pistons and connecting rods even when low-viscosity lubricating oil is used. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 2011-021530 Summary of the Invention [Problem to be solved by the invention]

[0007] The crankshaft of a hermetic refrigerant compressor forms the shaft of a compression element driven by an electric element, and this shaft is rotatably supported by a bearing. Although it is possible to further improve efficiency by reducing the sliding area between the shaft and the bearing (supporting portion), reducing the sliding area also reduces wear resistance.

[0008] In the reciprocating compressor (sealed refrigerant compressor) disclosed in the aforementioned Patent Document 1, the kinematic viscosity at 40°C is 3 mm 2 / S~10mm 2 Although a low-viscosity lubricant within the range of 1 / 5 is used, the target for improving wear resistance is the piston and connecting rod, which are not supported by bearings like a crankshaft, and the sliding area of ​​the supporting parts is not reduced to improve efficiency like a crankshaft.

[0009] 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 improve the reliability of a shaft portion supported by a bearing portion even when a lubricating oil with a lower viscosity is used. [Means for solving the problem]

[0010] In order to solve the above problems, the hermetic refrigerant compressor according to the present invention is a refrigerant compressor having a kinematic viscosity of 1 mm at 40°C in a sealed container. 2 / S~9mm 2and stores lubricating oil of 1 / S, and houses an electric element and a compression element driven by the electric element to compress a refrigerant, the compression element having a crankshaft with a main shaft and an eccentric shaft as a shaft portion, and a main bearing supporting the main shaft and an eccentric bearing supporting the eccentric shaft as bearing portions supporting the shaft portion, the sliding surface of the main shaft with the main bearing being a single surface or being 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 L, 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 L, and the ratio L / D of the single sliding length L to the outer diameter D of the main shaft is 0.51 or less, and further the lubricating oil contains sulfur or a compound containing sulfur as a sliding property improver.

[0011] According to the above configuration, the lubricating oil has a low viscosity, and whether the sliding surface of the main shaft is a single surface or multiple surfaces, the ratio L / D of the single sliding length L to the outer diameter D is 0.51 or less, and the lubricating oil contains a sulfur-based sliding property modifier. This allows the viscosity of the lubricating oil to be reduced, and even if the sliding area is reduced so that the ratio L / D is 0.51 or less, the sulfur-based sliding property modifier can provide good wear resistance in the sliding parts. As a result, a hermetic refrigerant compressor can be obtained that can improve the reliability of the shaft part supported by the bearing part, even when a lubricating oil with a lower viscosity is used.

[0012] In addition, the refrigeration / freezing device according to the present invention is configured to include a refrigerant circuit that includes the hermetic refrigerant compressor of the above configuration, a radiator, a pressure reducing device, and a heat absorber, and that connects these in a ring shape with piping.

[0013] According to the above configuration, the hermetic refrigerant compressor uses a low-viscosity lubricant oil to reduce the sliding area and has good shaft reliability. By providing a refrigeration / freezing device with such a highly efficient and reliable hermetic refrigerant compressor, the device can reduce its power consumption and achieve high reliability.

[0014] 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]

[0015] With the above-described configuration, the present invention has an advantage of providing a hermetic refrigerant compressor that can improve the reliability of the shaft portion supported by the bearing portion even when a lubricating oil with a lower viscosity is used. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a configuration of a refrigerant compressor according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic side view showing an example of the configuration of a crankshaft included in the refrigerant compressor shown in FIG. [Figure 3] FIG. 3A is a schematic diagram showing an example of the configuration of the crankshaft shown in FIG. 2 when the sliding surface is a single surface, and FIGS. 3B and 3C are schematic diagrams showing an example of the configuration of the crankshaft shown in FIG. 2 when the sliding surface is divided into multiple surfaces. [Figure 4] 2 is a schematic diagram showing an example of the configuration of a freezing / refrigeration device equipped with the refrigerant compressor shown in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] The hermetic refrigerant compressor according to the present disclosure contains a refrigerant having a kinematic viscosity of 1 mmHg at 40°C in a sealed container. 2 / S~9mm 2and stores lubricating oil of 1 / S, and houses an electric element and a compression element driven by the electric element to compress a refrigerant, the compression element having a crankshaft with a main shaft and an eccentric shaft as a shaft portion, and a main bearing supporting the main shaft and an eccentric bearing supporting the eccentric shaft as bearing portions supporting the shaft portion, the sliding surface of the main shaft with the main bearing being a single surface or being 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 L, 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 L, and the ratio L / D of the single sliding length L to the outer diameter D of the main shaft is 0.51 or less, and further the lubricating oil contains sulfur or a compound containing sulfur as a sliding property improver.

[0018] According to the above configuration, the lubricating oil has a low viscosity, and whether the sliding surface of the main shaft is a single surface or multiple surfaces, the ratio L / D of the single sliding length L to the outer diameter D is 0.51 or less, and the lubricating oil contains a sulfur-based sliding property modifier. This allows the viscosity of the lubricating oil to be reduced, and even if the sliding area is reduced so that the ratio L / D is 0.51 or less, the sulfur-based sliding property modifier can provide good wear resistance in the sliding parts. As a result, a hermetic refrigerant compressor can be obtained that can improve the reliability of the shaft part supported by the bearing part, even when a lubricating oil with a lower viscosity is used.

[0019] In the hermetic refrigerant compressor having the above configuration, when the sliding surface is divided into a plurality of surfaces, the compressor may be further configured such that, when the sum of axial lengths of the plurality of sliding surfaces is defined as a total sliding length Lt, a ratio Lt / D of the total sliding length Lt to the outer diameter D is 1.26 or less.

[0020] According to the above configuration, when there are multiple sliding surfaces, the sliding area is reduced so that the ratio L / D is 0.51 or less and the ratio Lt / D of the total sliding length Lt to the outer diameter D is 1.26 or less. This makes it possible to further improve the wear resistance of the sliding part derived from the sulfur-based sliding properties modifier when the sliding area is reduced using a low-viscosity lubricating oil.

[0021] In the hermetic refrigerant compressor having the above configuration, the ratio L / D may be 0.15 or more.

[0022] According to the above configuration, if the ratio L / D is 0.15 or more, the sliding area is not excessively reduced, and therefore, when the sliding area is reduced by using a low-viscosity lubricating oil, the wear resistance of the sliding part can be suitably achieved by using a sulfur-based sliding property modifier.

[0023] In the hermetic refrigerant compressor having the above configuration, the ratio Lt / D may be 0.3 or more.

[0024] According to the above configuration, if the ratio Lt / D is 0.3 or more, the sliding area is not excessively reduced even when the sliding surface is divided into multiple surfaces. Therefore, when the sliding area is reduced by using a low-viscosity lubricating oil, the wear resistance of the sliding part can be suitably achieved by using a sulfur-based sliding property modifier.

[0025] In the hermetic refrigerant compressor having the above configuration, the content of the sliding characteristics improver may be 100 ppm or more when converted into elemental sulfur weight.

[0026] According to the above configuration, a sulfur-based sliding property modifier is added to the lubricating oil so that the sulfur content is 100 ppm or more when converted to elemental sulfur by weight. This makes it possible to preferably achieve the wear resistance of the sliding parts derived from the sulfur-based sliding property modifier when a low-viscosity lubricating oil is used to reduce the sliding area.

[0027] In the hermetic refrigerant compressor having the above configuration, the lubricating oil may further contain a phosphorus-based extreme pressure additive.

[0028] According to the above-described configuration, by adding a phosphorus-based extreme pressure additive to the lubricating oil in addition to a sulfur-based sliding property improver, it is possible to achieve favorable wear reduction and the like in the sliding parts.

[0029] In the hermetic refrigerant compressor having the above configuration, the electric element may be inverter-driven at a plurality of operating frequencies.

[0030] According to the above configuration, the wear resistance of the sliding parts derived from the sulfur-based sliding property modifier can be achieved even during low-speed or high-speed inverter-driven operation, thereby improving the reliability of the hermetic refrigerant compressor.

[0031] 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 with piping.

[0032] According to the above configuration, the hermetic refrigerant compressor uses a low-viscosity lubricant oil to reduce the sliding area and has good shaft reliability. By providing a refrigeration / freezing device with such a highly efficient and reliable hermetic refrigerant compressor, the device can reduce its power consumption and achieve high reliability.

[0033] Representative embodiments of the present invention will be described below with reference to the drawings. Note that the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant description will be omitted.

[0034] (Embodiment 1) [Refrigerant compressor configuration] First, a representative configuration example of a hermetic refrigerant compressor according to a first embodiment of the present disclosure will be specifically described with reference to Figures 1 and 2. Figure 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 the first embodiment of the present disclosure. Figure 2 is a schematic side view showing an example of the configuration of a crankshaft 108, which is a shaft portion provided in refrigerant compressor 100.

[0035] As shown in Fig. 1, the refrigerant compressor 100 is filled with, for example, R600a as a refrigerant in a sealed container 101, and mineral oil is stored at the bottom as lubricating oil 103. In this disclosure, the lubricating oil 103 has a kinematic viscosity of 1 mm at 40°C. 2 / S~9mm 2 / S. In the first embodiment, the lubricating oil 103 is a low-viscosity mineral oil, but as will be described later, the lubricating oil 103 is not limited to this. As will be described later, the lubricating oil 103 contains at least a sulfur-based sliding property improver (or a wear inhibitor), and may further contain an extreme-pressure additive.

[0036] Also housed within the sealed container 101 are an electric element 106 and a compression element 107. The electric element 106 is composed of a stator 104 and a rotor 105. The compression element 107 is a reciprocating element driven by the electric element 106, and includes a crankshaft 108, a cylinder block 112, a piston 120, etc.

[0037] 2, crankshaft 108 is made up of main shaft 109 to which rotor 105 is press-fitted and eccentric shaft 110 formed eccentrically with respect to main shaft 109. In the first embodiment, the outer peripheral surface of main shaft 109 of crankshaft 108 includes first sliding surface 111a, second sliding surface 111b, and non-sliding outer peripheral surface 111c. An oil supply pump (not shown) is provided at the lower end of crankshaft 108.

[0038] In the first embodiment, cylinder block 112 is made of, for example, cast iron, and has a substantially cylindrical bore 113 formed therein, as well as a main bearing 114 that supports main shaft 109 of crankshaft 108. The inner peripheral surface of main bearing 114 is in slidable contact with first sliding surface 111a and second sliding surface 111b of the outer peripheral surface of main shaft 109, but is not in contact with non-sliding outer peripheral surface 111c.

[0039] 1, the eccentric shaft 110 of the crankshaft 108 is located above the refrigerant compressor 100, and the main shaft 109 is located below the refrigerant compressor 100. Therefore, this up-down positional relationship (direction) will be used when describing the position of the crankshaft 108. For example, the upper end of the eccentric shaft 110 faces the upper inner surface of the sealed container 101, and the lower end of the eccentric shaft 110 is connected to the main shaft 109. The upper end of the main shaft 109 is connected to the eccentric shaft 110, and the lower end of the main shaft 109 faces the lower inner surface of the sealed container 101, and the lower end of the main shaft 109 is immersed in the lubricating oil 103.

[0040] In this disclosure, the term "sliding surface" refers to a surface of the outer circumferential surface of the shaft portion that is in slidable contact with the inner circumferential surface of the bearing portion. Non-sliding outer circumferential surface 111c constitutes part of the outer circumferential surface of main shaft 109, but unlike first sliding surface 111a and second sliding surface 111b, non-sliding outer circumferential surface 111c is a surface that is recessed (or concave) from the sliding surfaces (first sliding surface 111a and second sliding surface 111b) so as not to contact the inner circumferential surface of the bearing portion. In other words, the diameter or radius of the portion of main shaft 109 that becomes the sliding surface is larger than the diameter or radius of the portion that becomes non-sliding outer circumferential surface 111c.

[0041] A piston 120 is inserted into the bore 113 so as to be able to reciprocate, thereby forming a compression chamber 121. The piston pin 115 has, for example, a substantially cylindrical shape, and is disposed parallel to the eccentric shaft 110. The piston pin 115 is engaged in a piston pin hole formed in the piston 120 so as not to be able to rotate.

[0042] The connecting means 117 is made of, for example, an aluminum casting, and includes an eccentric bearing 119 that supports the eccentric shaft 110, connecting the eccentric shaft 110 to the piston 120 via a piston pin 115. The end face of the bore 113 is sealed by a valve plate 122.

[0043] In this disclosure, the main shaft 109 and eccentric shaft 110 of the crankshaft 108 are collectively referred to as the "shaft portion." Also, the main bearing 114 of the cylinder block 112 that supports the main shaft 109 and the eccentric bearing 119 of the connecting means 117 that supports the eccentric shaft 110 are collectively referred to as the "bearing portion."

[0044] The cylinder head 123 forms a high-pressure chamber (not shown) and is fixed to the valve plate 122 on the opposite side to the bore 113. A suction tube (not shown) is fixed to the sealed container 101 and connected to the low-pressure side (not shown) of the refrigeration cycle to guide refrigerant gas into the sealed container 101. A suction muffler 124 is sandwiched between the valve plate 122 and the cylinder head 123.

[0045] Here, the main shaft 109 and main bearing 114 of the crankshaft 108, the piston 120 and bore 113, the piston pin 115 and the connecting rod of the connecting means 117, the eccentric shaft 110 of the crankshaft 108 and the eccentric bearing 119 of the connecting means 117, etc. all form sliding parts with respect to each other.

[0046] In the refrigerant compressor 100 configured as described above, first, electric power is supplied from a commercial power source (not shown) to the electric element 106, causing the rotor 105 of the electric element 106 to rotate. The rotor 105 rotates the crankshaft 108, and the eccentric motion of the eccentric shaft 110 drives the piston 120 via the connecting means 117 and the piston pin 115. The piston 120 reciprocates within the bore 113, sucking in the refrigerant gas that has been introduced into the sealed container 101 via the suction tube through the suction muffler 124 and compressing it in the compression chamber 121.

[0047] The specific driving method of the refrigerant compressor 100 is not particularly limited. For example, the refrigerant compressor 100 may be driven by simple on-off control, or may be inverter-driven at multiple operating frequencies. In inverter drive, in order to optimize the operational control of the refrigerant compressor 100, there are periods of low-speed operation in which the amount of oil supplied to each sliding part is reduced, and periods of high-speed operation in which the rotation speed of the electric element 106 is increased. Here, in the refrigerant compressor 100, as will be described later, the wear resistance of the main shaft 109 can be improved, thereby improving the reliability of the refrigerant compressor 100.

[0048] Of the multiple sliding parts included in the refrigerant compressor 100, the main shaft 109 of the crankshaft 108 is rotatably fitted to the main bearing 114 to form a sliding part. Therefore, for convenience of explanation, the sliding part formed by the main shaft 109 and the main bearing 114 will be referred to as the "main shaft sliding part." Similarly, the eccentric shaft 110 of the crankshaft 108 is rotatably fitted to the eccentric bearing 119 to form a sliding part. Therefore, for convenience of explanation, the sliding part formed by the eccentric shaft 110 and the eccentric bearing 119 will be referred to as the "eccentric shaft sliding part." Furthermore, the "main shaft sliding part" and the "eccentric shaft sliding part" will be collectively referred to as the "shaft sliding part."

[0049] As the crankshaft 108 rotates, the oil supply pump supplies lubricating oil 103 to each sliding part, thereby lubricating each sliding part. The lubricating oil 103 also acts as a seal between the piston 120 and the bore 113.

[0050] [Configuration of shaft sliding part] Next, an example of a specific configuration of the shaft sliding part according to the present disclosure will be described in detail with reference to Figures 3A to 3C. Figure 3A is a schematic diagram showing an example of the configuration of the crankshaft 108 shown in Figure 2 when the sliding surface is a single surface, and Figures 3B and 3C are schematic diagrams showing an example of the configuration of the crankshaft 108 shown in Figure 2 when the sliding surface is divided into multiple surfaces.

[0051] In the example shown in FIG. 2, the main shaft 109 of the crankshaft 108, which is a shaft portion, has a first sliding surface 111a and a second sliding surface 111b, so it can be said that the sliding surface of the main shaft 109 is divided into multiple surfaces. The configuration of the main shaft 109 shown in FIG. 2, i.e., the configuration in which the sliding surface is divided into two surfaces, corresponds to the schematic diagram shown in FIG. 3B. 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. 3A, the outer peripheral surface of the main shaft 109 may not be divided into multiple sliding surfaces but may have only a single sliding surface 111.

[0052] 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. 2 and 3B, this recessed portion constitutes the non-sliding outer peripheral surface 111c. The specific shape of the recessed portion is also not particularly limited, and for example, its depth may be any depth as long as it does not affect the rigidity, strength, etc. of the main shaft 109. 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 (decreased or reduced).

[0053] When the sliding surface is divided into multiple parts, the number of sliding surfaces is not particularly limited. As shown in FIGS. 2 and 3B, the sliding surface may be divided into two surfaces, a first sliding surface 111a and a second sliding surface 111b. As shown in FIG. 3C, the sliding surface may be divided into three surfaces, a first sliding surface 111d, a second sliding surface 111e, and a third sliding surface 111f. Alternatively, the sliding surface may be divided into four or more surfaces. In the configuration shown in FIG. 3C, a first non-sliding outer peripheral surface 111g, which is a recess similar to the non-sliding outer peripheral surface 111c, is located between the first sliding surface 111d and the second sliding surface 111e, and a second non-sliding outer peripheral surface 111h is located between the second sliding surface 111e and the third sliding surface 111f.

[0054] Here, in the shaft portion according to the present disclosure, by setting the ratio of the axial length of the sliding surface to the outer diameter (diameter) of the portion that becomes the sliding surface to a predetermined value or less, the sliding area can be reduced without substantially affecting the wear resistance. Specifically, when the sliding surface is a single surface (for example, see FIG. 3A), the axial length of the sliding surface is defined as the single sliding length L, and when the sliding surface is divided into a plurality of surfaces (for example, FIGS. 3B or 3C), the axial length of the sliding surface with the minimum axial length is defined as the single sliding length L. And when the outer diameter (diameter) of the portion that becomes the sliding surface in the shaft portion is the outer diameter D, the shaft portion is designed such that the ratio L / D of the single sliding length L to the outer diameter D of the shaft portion is 0.51 or less.

[0055] In FIG. 3A, for the convenience of explaining the outer diameter D and the single sliding length L, the length L (single sliding length L) of the single sliding surface 111 with respect to the outer diameter D is shown enlarged. If it is as shown in this FIG. 3A, the ratio L / D exceeds 0.51. However, actually, for example, by forming a concave portion (non-sliding outer peripheral surface) in the upper part (eccentric shaft 110 side) or the lower part (lubricating oil 103 side) of the main shaft 109 as seen from the single sliding surface 111, the ratio L / D can be set to 0.51 or less (L / D≦0.51).

[0056] In FIG. 3B, the sliding surface is divided into a first sliding surface 111a and a second sliding surface 111b. In the example shown in FIG. 3B, the axial length La of the upper first sliding surface 111a is smaller than the axial length Lb of the lower second sliding surface 111b (La < Lb). In this case, since the first sliding surface 111a becomes the "sliding surface with the minimum length", its length La corresponds to the single sliding length L (L = La). In this example, it is sufficient that La / D is 0.51 or less on the first sliding surface 111a.

[0057] Note that also in FIG. 3B, similar to FIG. 3A, for the convenience of explanation of the outer diameter D and the length La of the first sliding surface 111a, the length La is shown enlarged with respect to the outer diameter D. Also in this case, by increasing the axial length of the non-sliding outer peripheral surface 111c or providing a non-sliding outer peripheral surface (concave portion) not shown above the first sliding surface 111a, the ratio L / D can be set to 0.51 or less.

[0058] In FIG. 3C, the sliding surface is divided into a first sliding surface 111d, a second sliding surface 111e, and a third sliding surface 111f. In the example shown in FIG. 3C, the length Le of the second sliding surface 111e at the center is smaller than the axial length Ld of the upper first sliding surface 111d, and the length Ld is smaller than the length Lf of the lower third sliding surface 111f (Le < Ld < Lf). In this case, since the second sliding surface 111e becomes the "sliding surface with the minimum length", its length Le corresponds to the single sliding length L (L = Le). In this example, it is sufficient if Le / D is 0.51 or less on the second sliding surface 111e.

[0059] In the present disclosure, the lower limit value of the ratio L / D 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 L / D in the present disclosure, the range of 0.15 to 0.51 can be mentioned. Further, as a more preferable lower limit of the ratio L / D, 0.30 can be mentioned, and as an even more preferable lower limit, 0.42 can be mentioned.

[0060] When the ratio L / D exceeds 0.51, when a low-viscosity lubricating oil 103 (kinematic viscosity at 40°C is within the range of 1 mm 2 / S to 9 mm 2 / S) is used, even if a sulfur-based sliding property modifier described later is added to the lubricating oil 103, sufficient wear resistance cannot be obtained. On the other hand, if the ratio L / D is less than 0.15, although it depends on various conditions of the shaft portion, there is a possibility that the sliding surface becomes too narrow. Generally, if the ratio L / D is 0.15 or more, the sliding area will not be excessively reduced, so even if a low-viscosity lubricating oil 103 is used, the wear resistance of the shaft sliding portion can be suitably realized by a sulfur-based sliding property modifier.

[0061] In the present disclosure, when the sliding surface is divided into multiple surfaces, in addition to the condition that the ratio L / D is 0.51 or less, it is preferable to satisfy the condition that when the sum of the axial lengths of the multiple sliding surfaces is the total sliding length Lt, the ratio Lt / D of the total sliding length Lt to the outer diameter D is 1.26 or less (Lt / D≦1.26).

[0062] For example, in the example shown in FIG. 3B, the sum of the length La of the first sliding surface 111a and the length Lb of the second sliding surface 111b is the total sliding length Lt (Lt = La + Lb). Therefore, in this example, it is sufficient that La + Lb ≦ 1.26. Also, in the example shown in FIG. 3C, the sum of the length La of the first sliding surface 111d, the length Le of the second sliding surface 111e, and the length Lf of the third sliding surface 111f is the total sliding length Lt (Lt = Ld + Le + Lf). Therefore, in this example, it is sufficient that Ld + Le + Lf ≦ 1.26.

[0063] Thus, when there are multiple sliding surfaces, if the ratio L / D is 0.51 or less and the ratio Lt / D is 1.26 or less, the wear resistance of the shaft sliding part resulting from the sulfur-based sliding property modifier can be further improved when a low-viscosity lubricating oil 103 is used to reduce the sliding area.

[0064] In the present disclosure, the lower limit of the ratio Lt / D is not particularly limited, but a preferable example of the lower limit is 0.3 or more. Therefore, a preferable range of the ratio Lt / D in the present disclosure is 0.3 to 1.26. A more preferable lower limit of the ratio Lt / D is 0.60, and an even more preferable lower limit is 0.99. Generally, if the ratio Lt / D is 0.3 or more, the sliding area is not excessively reduced even when the sliding surface is divided into multiple surfaces. Therefore, even if a low-viscosity lubricating oil 103 is used, the wear resistance of the shaft sliding portion can be suitably achieved by the sulfur-based sliding property modifier.

[0065] 3A to 3C, the ratio L / D or the ratio Lt / D is described for the main shaft 109 of the crankshaft 108 as the shaft portion. However, the present disclosure is not limited to this, and the same applies to the eccentric shaft 110. That is, when the sliding surface of the eccentric shaft 110 with the eccentric bearing 119 is a single surface, and the axial length of the sliding surface is defined as a single sliding length L, or when the sliding surface of the eccentric shaft 110 is divided into multiple surfaces, and the axial length of the sliding surface with the shortest axial length is defined as a single sliding length L, the ratio L / D of the single sliding length L to the outer diameter D of the eccentric shaft 110 may be 0.51 or less. Furthermore, when the sum of the axial lengths of the multiple sliding surfaces of the eccentric shaft 110 is defined as a total sliding length Lt, the ratio Lt / D of the total sliding length Lt to the outer diameter D of the eccentric shaft 110 may be 1.26 or less.

[0066] Therefore, in the refrigerant compressor 100 according to the present disclosure, it is sufficient that the ratio L / D is 0.51 or less in at least one of the shaft parts, that is, the main shaft 109 and the eccentric shaft 110, and it is also sufficient that the ratio Lt / D is 1.26 or less in at least one of the main shaft 109 and the eccentric shaft 110.

[0067] [Lubricant composition] Next, a more specific configuration of the lubricating oil 103 stored in the sealed container 101 will be described in detail.

[0068] The lubricating oil 103 according to the present disclosure has a kinematic viscosity of 1 mm at 40°C. 2 / S~9mm 2 / S. A typical example of the lubricating oil 103 is at least one oily substance selected from the group consisting of mineral oil, alkylbenzene oil, and ester oil. Only one of these oily substances may be used, or two or more may be used in combination. The combination of two or more oily substances mentioned here includes, for example, a combination of two or more different oily substances classified as mineral oil, as well as a combination of one or more oily substances classified as mineral oil with one or more oily substances classified as alkylbenzene oil (or one or more oily substances classified as ester oil).

[0069] The lubricating oil 103 according to the present disclosure contains a sulfur-based sliding property modifier in addition to the oily substance described above. The sulfur-based sliding property modifier may be any agent capable of reacting with sulfur and the material used for the shaft portion (shaft material). Therefore, the sliding property modifier may be sulfur itself or a sulfur compound containing sulfur and capable of reacting with the shaft portion material. For example, if the shaft portion is made of an iron-based material, examples of sulfur compounds that can be used as sliding property modifiers include sulfurized olefins, sulfide compounds (e.g., dibenzyl (di)sulfide (DBDS)), xanthates, thiadiazoles, thiocarbonates, sulfurized oils and fats, sulfurized esters, dithiocarbamates, and sulfurized terpenes.

[0070] The content of the sulfur-based sliding properties improver in the lubricating oil 103 is not particularly limited, but preferably the sliding properties improver is added to the lubricating oil 103 so that the content is 100 ppm or more when converted to elemental sulfur weight. The lower limit of the amount (content) of the sliding properties 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.

[0071] 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 lubricating oil 103 is used and the sliding area of ​​the shaft sliding part is reduced, it may not be possible to achieve suitable wear resistance of the 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.

[0072] The sulfur-based sliding property modifier used in the present disclosure can be a compound similar to that of a known sulfur-based extreme pressure additive, but it is also possible to use one that is relatively more reactive with the shaft material than known extreme pressure additives, or to add a larger amount (content) of known extreme pressure additives to the lubricating oil 103 than is generally added.

[0073] 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, and this coating suppresses wear, seizure, fusion, etc. of the sliding members.

[0074] It is also known that sulfur-containing compounds easily react with copper. For example, Reference 1: JP 2006-117720 A discloses that although sulfur-containing anti-wear agents are effective in preventing the corrosive wear of lead-containing sliding materials, they are also susceptible to sulfidation corrosion in sliding materials containing non-ferrous base metals other than lead, such as copper (paragraphs

[0006] to

[0007] ).

[0075] In the refrigerant compressor 100, copper wire is used as the winding of the electric element 106. 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 must be taken to avoid or suppress corrosion of copper members (or copper-containing members) included in the refrigerant compressor 100 or the freezing / refrigeration device, and to prevent a decrease in their reliability.

[0076] As disclosed in Reference 2: Patent No. 5671695, when a sulfur-based extreme pressure additive is used in the refrigeration oil of a refrigeration / freezing device, the applicant uses a sulfur-based extreme pressure additive with a sulfur bridge number of 3 or less so as not to react with copper in the refrigerant circulation path, and preferably uses a metal deactivator in combination.

[0077] In response to this, the inventors of the present invention have conducted extensive research, including experimental verification, and have found that when a low-viscosity lubricating oil 103 is used and the sliding area of ​​the shaft sliding portion is reduced so that the aforementioned ratio L / D is 0.51 or less, by using a more reactive sulfur-based compound as the sliding property modifier or by increasing the amount added (content), not only can good wear resistance be achieved but also corrosion of copper members (or copper-containing members) can be substantially avoided.

[0078] Furthermore, in the refrigerant compressor 100 according to the present disclosure, in addition to the sulfur-based sliding property improver, a known extreme pressure additive may be added to the lubricating oil 103. 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 lubricating oil composition, or two or more types may be added in appropriate combination.

[0079] Among these extreme pressure additives, phosphorus-based compounds are preferably used. Typical phosphorus-based compounds include tricresyl phosphate (TCP), tributyl phosphate (TBP), and triphenyl phosphate (TPP), with TCP being more preferably used. By adding a phosphorus-based extreme pressure additive to the lubricating oil 103 in addition to a sulfur-based sliding property modifier, it is possible to achieve good wear reduction in the sliding parts of the shaft.

[0080] The amount of the extreme pressure additive added to the lubricating oil composition is not particularly limited, but for example, when the lubricating oil 103 (oily substance) is a low-polarity substance such as mineral oil or alkylbenzene oil, a suitable amount to be added is in the range of 0.5 to 8.0 wt %, and a more preferred range is 1 to 3 wt %.

[0081] Additionally, in the refrigerant compressor 100 according to the present disclosure, various known additives may be added to the lubricating oil 103 in addition to the sliding property improver and extreme pressure additive. Various additives known in the field of lubricating oils 103 can be suitably used as such additives, and representative examples include oiliness agents, antioxidants, acid scavengers, metal deactivators, antifoaming agents, corrosion inhibitors, and dispersants. In other words, the lubricating oil 103 used in the refrigerant compressor 100 according to the present disclosure is a lubricating oil composition comprising at least an oily substance and a sliding property improver, and this lubricating oil composition may contain an extreme pressure additive (particularly a phosphorus-based extreme pressure additive) and other additives.

[0082] As described above, in the refrigerant compressor 100 according to the present disclosure, (1) the lubricating oil 103 is a lubricating oil having a kinematic viscosity of 1 mm at 40°C. 2 / S~9mm 2 / S, (2) the ratio L / D of the single sliding length L to the outer diameter D of the shaft portion is 0.51 or less, and (3) a sulfur-based sliding property modifier is used. When the sliding surface is divided into multiple surfaces, it preferably satisfies the condition (4) the ratio Lt / D of the total sliding length Lt to the outer diameter D is 1.26 or less. By satisfying these conditions, the shaft portion and the bearing portion can be well lubricated, thereby effectively suppressing wear of the sliding portion of the shaft portion. As a result, the reliability of the refrigerant compressor 100 can be further improved.

[0083] As described above, the refrigerant compressor 100 according to the present disclosure may be inverter-driven at a plurality of operating frequencies. In inverter drive, the electric element 106 may be operated at a low rotation speed (low-speed operation) or a high rotation speed (high-speed operation). When operated at a low rotation speed, the amount of lubricating oil 103 supplied to the sliding shaft portion decreases. In the present disclosure, the sliding area of ​​the sliding shaft portion is reduced, but good wear resistance can be achieved even when the amount of lubricating oil 103 supplied decreases.

[0084] Furthermore, good wear resistance can be achieved even when the rotation speed changes from low to high (when the rotation speed of the electric element 106 increases). Therefore, the wear resistance derived from the sulfur-based sliding property modifier can be achieved in the shaft sliding portion, even during low-speed or high-speed operation in inverter drive. As a result, the reliability of the refrigerant compressor 100 can be improved, and the operating efficiency can also be improved.

[0085] As described above, in the refrigerant compressor 100 according to the present disclosure, the lubricating oil 103 has a low viscosity, and whether the sliding surface of the shaft portion is a single surface or multiple surfaces, the ratio L / D of the single sliding length L to the outer diameter D is 0.51 or less, and the lubricating oil 103 contains a sulfur-based sliding property modifier. Thus, even if the viscosity of the lubricating oil 103 is reduced and the sliding area is reduced so that the ratio L / D is 0.51 or less, the sulfur-based sliding property modifier can provide good wear resistance in the sliding portion. As a result, a hermetic refrigerant compressor can be obtained that can improve the reliability of the shaft portion supported by the bearing portion, even when a lubricating oil 103 with a lower viscosity is used.

[0086] (Embodiment 2) In the present second embodiment, an example of a refrigeration / freezing device including the refrigerant compressor 100 described in the first embodiment will be specifically described with reference to Fig. 4. Fig. 4 schematically shows the general configuration of a refrigeration / freezing device including the refrigerant compressor 100 according to the first embodiment. Therefore, in the present second embodiment, only the general outline of the basic configuration of the refrigeration / freezing device will be described.

[0087] As shown in Fig. 4, the refrigeration / freezing device according to the second embodiment includes a main body 275, a partition wall 278, a refrigerant circuit 270, and the like. The main body 275 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 275 is partitioned by the partition wall 278 into an item storage space 276 and a machine room 277. A blower (not shown) is provided in the storage space 276. The interior of the main body 275 may be partitioned into spaces other than the storage space 276 and the machine room 277.

[0088] Refrigerant circuit 270 is configured to cool the inside of storage space 276, and includes, for example, refrigerant compressor 100 described in the first embodiment, a radiator 272, a pressure reducing device 273, and a heat absorber 274, which are connected in a ring shape by piping. Heat absorber 274 is disposed in storage space 276. The cooling heat of heat absorber 274 is agitated by a blower (not shown) so as to circulate within storage space 276, as indicated by the dashed arrows in FIG. 4. This cools the inside of storage space 276.

[0089] As described in the first embodiment, the refrigerant compressor 100 provided in the refrigerant circuit 270 uses, as the lubricating oil 103, a lubricating oil having a kinematic viscosity of 1 mm at 40°C. 2 / S~9mm 2 / S, (2) the ratio L / D of the single sliding length L to the outer diameter D of the shaft portion is 0.51 or less, and (3) a sulfur-based sliding property improver is used, and when the sliding surface is divided into multiple surfaces, preferably the ratio Lt / D of the total sliding length Lt to the outer diameter D is 1.26 or less. This further improves the reliability of the refrigerant compressor 100.

[0090] As described above, the refrigeration / freezer according to the second embodiment is equipped with the refrigerant compressor 100 according to the first embodiment. In this refrigerant compressor 100, low viscosity lubricant oil 103 is used to reduce the sliding area of ​​the shaft sliding parts, and the shaft has good reliability. By providing the refrigeration / freezer with such a highly efficient and reliable hermetic refrigerant compressor, the power consumption of the refrigeration / freezer can be reduced and reliability can be improved.

[0091] 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.

[0092] 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]

[0093] As described above, the present invention provides a refrigerant compressor that uses low-viscosity lubricating oil and has excellent reliability, and a refrigeration / freezing device that uses this refrigerant compressor. Therefore, the present invention can be widely applied to various devices that use a refrigeration cycle. [Explanation of symbols]

[0094] 100: Refrigerant compressor 101: Airtight container 103: Lubricating oil 106:Electric element 107: Compression element 108: Crankshaft 109: Main shaft (shaft part) 110: Eccentric shaft (shaft) 111: Single sliding surface 111a: First sliding surface 111b: Second sliding surface 111c: Non-sliding outer peripheral surface 111d: First sliding surface 111e: Second sliding surface 111f: Third sliding surface 111g: First non-sliding outer surface 111h: Second non-sliding outer surface 112: Cylinder block 114: Main bearing (bearing part) 119: Eccentric bearing (bearing part) 270: Refrigerant circuit 272: Heat sink 273: Pressure reducing device 274: Heat absorber

Claims

1. In a sealed container, a solution with a kinematic viscosity of 1 mm at 40°C 2 / S-9mm 2 / S lubricating oil is stored, and an electric element and a compression element that is driven by the electric element and compresses a refrigerant are accommodated, the compression element includes a crankshaft having a main shaft and an eccentric shaft as a shaft portion made of an iron-based material, and a main bearing supporting the main shaft and an eccentric bearing supporting the eccentric shaft as bearing portions supporting the shaft portion, The sliding surface of the main shaft with the main bearing is divided into two surfaces, When the axial length of the sliding surface having the shortest axial length of the two sliding surfaces is defined as a single sliding length L, a ratio L / D of the single sliding length L to an outer diameter D of the spindle is 0.51 or less and 0.15 or more, Furthermore, the lubricating oil contains mineral oil as an oily substance and also contains sulfur or a compound containing sulfur as a sliding property improver in a content of 100 ppm or more when converted to sulfur element weight. Hermetic refrigerant compressor.

2. Furthermore, when the sum of the axial lengths of the two sliding surfaces is defined as a total sliding length Lt, the ratio Lt / D of the total sliding length Lt to the outer diameter D is 1.26 or less.

2. The hermetic refrigerant compressor according to claim 1.

3. The ratio Lt / D is 0.3 or more.

3. The hermetic refrigerant compressor according to claim 2.

4. The lubricating oil further contains a phosphorus-based extreme pressure additive. The hermetic refrigerant compressor according to any one of claims 1 to 3.

5. The electric element is inverter-driven at a plurality of operating frequencies. The hermetic refrigerant compressor according to any one of claims 1 to 4.

6. A refrigerant circuit including the hermetic refrigerant compressor according to any one of claims 1 to 5, 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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