Slide bearing for reciprocating compressor, reciprocating compressor, and reciprocating compressor for high-temperature heat pump device

Abstract

A slide bearing for a reciprocating compressor comprises: a first end surface in an axial direction; a second end surface that is positioned on the opposite side from the first end surface in the axial direction; and a bearing surface that is formed between the first end surface and the second end surface, and that faces an outer circumferential surface of a crankshaft of a reciprocating compressor, with a gap between the bearing surface and the crankshaft. The bearing surface includes: a circumferential groove that is provided along the circumferential direction of the bearing surface; an oil supply port that opens to the circumferential groove; and at least one oil discharge groove that is in communication with the circumferential groove at a different circumferential direction position than the oil supply port, and that extends to at least one of the first end surface and the second end surface.

Description

Reciprocating compressor sliding bearings, reciprocating compressors and reciprocating compressors for high-temperature heat pump equipment

[0001] The present disclosure relates to a sliding bearing for a reciprocating compressor, a reciprocating compressor, and a reciprocating compressor for a high-temperature heat pump device.

[0002] Conventionally, a plain bearing has been used in a reciprocating compressor to rotatably support a crankshaft. The plain bearing forms an oil film of lubricating oil supplied from an external source in a bearing gap between a bearing surface and the outer circumferential surface of the crankshaft, and rotatably supports the crankshaft via the oil film.

[0003] For example, Patent Document 1 describes a plain bearing for a screw compressor, rather than a plain bearing for a reciprocating compressor, in which lubricating oil is supplied from an oil supply hole provided on the bearing surface of the plain bearing, and the shaft of the screw rotor is rotatably supported via an oil film of the lubricating oil.

[0004] Japanese Patent Application Publication No. 63-289282

[0005] In the sliding bearings of reciprocating compressors, the reliability of the sliding bearings can be reduced by a rise in oil film temperature caused by frictional heat generated by the rotation of the crankshaft, so an allowable temperature range is sometimes set to maintain the reliability of the sliding bearing.One possible way to keep the oil film temperature within the allowable temperature range of the sliding bearing is to supply new low-temperature lubricating oil from outside the sliding bearing.

[0006] However, some of the newly supplied low-temperature lubricating oil may not be effectively drawn into the bearing gap and may instead flow out of the sliding bearing, making it impossible to suppress the temperature rise of the oil film and potentially preventing the oil film temperature from falling within the allowable temperature range of the sliding bearing.

[0007] In addition, the bearing surface of the plain bearing of the screw compressor described in Patent Document 1 is provided with oil grooves that extend to both axial end faces of the plain bearing and are located at the same circumferential position as the oil feed holes. As a result, new lubricating oil supplied from the oil feed holes is not effectively drawn into the bearing gap and is prone to flow out of the plain bearing via the oil grooves.

[0008] In view of the above circumstances, at least some embodiments of the present invention aim to provide a sliding bearing for a reciprocating compressor, a reciprocating compressor, and a reciprocating compressor for a high-temperature heat pump device that can suppress a temperature rise in the oil film by increasing the amount of low-temperature lubricating oil supplied to the bearing gap.

[0009] A plain bearing for a reciprocating compressor according to at least some embodiments of the present invention comprises: a first end face in the axial direction; a second end face located on the opposite side of the first end face in the axial direction from the first end face; and a bearing surface formed between the first end face and the second end face and facing an outer peripheral surface of the crankshaft of the reciprocating compressor across a gap between the crankshaft and the bearing surface, wherein the bearing surface includes: a circumferential groove provided along the circumferential direction of the bearing surface; an oil supply port opening into the circumferential groove; and at least one oil drain groove communicating with the circumferential groove at a circumferential position different from the oil supply port and extending to at least one of the first end face or the second end face.

[0010] In at least some embodiments of the present invention, an oil drain groove is provided that communicates with the circumferential groove at a circumferential position different from the oil filler opening and extends to at least one of the axial end faces of the plain bearing. This lengthens the main lubricating oil discharge path from the oil filler opening to the oil drain groove. Therefore, low-temperature lubricating oil supplied from the oil filler opening is more likely to be drawn into the bearing gap before being discharged from the plain bearing via the oil drain groove. This makes it possible to increase the amount of low-temperature lubricating oil supplied to the bearing gap, thereby suppressing the temperature rise of the oil film.

[0011] 3B is a schematic diagram of a reciprocating compressor according to one embodiment; FIG. 3C is a diagram of a crankshaft and a plain bearing according to one embodiment, viewed from the axial direction of the crankshaft; FIG. 3D is a cross-sectional view of the crankshaft and plain bearing according to one embodiment in the axial direction, and is a cross-sectional view of the crankshaft and plain bearing taken at the position of the oil filler port; FIG. 3E is a schematic diagram of a bearing surface of a plain bearing according to one embodiment, developed in a plane; FIG. 3F is a schematic diagram of a bearing surface of a plain bearing according to another embodiment, developed in a plane; FIG. 3G is a diagram showing an embodiment in region A shown in FIG. 3B, and is a diagram showing the configurations of an oil drain groove and an oil pocket; FIG. 3H is a diagram showing another embodiment in region A shown in FIG. 3B, and is a diagram showing the configurations of an oil drain groove and an oil pocket; FIG. 3I is a perspective view of a plain bearing according to one embodiment, and is a perspective cross-sectional view of the plain bearing taken along the axial direction; FIG. 3I is a schematic diagram of an oil supply system in a reciprocating compressor according to one embodiment; FIG. 3I is a schematic diagram of a high-temperature heat pump device according to one embodiment.

[0012] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0013] First, the configuration of a reciprocating compressor according to some embodiments will be described with reference to Fig. 1. Fig. 1 is a schematic diagram of a reciprocating compressor according to one embodiment.

[0014] As shown in Fig. 1, the reciprocating compressor 3 includes a cylinder 10, a piston 20 for compressing a fluid in the cylinder 10, and a crankshaft 40 connected to the piston 20 via a connecting rod 30. The crankshaft 40 rotates around a central axis O of the crankshaft 40 as a rotation axis. The rotational motion of the crankshaft 40 is converted into reciprocating motion by the connecting rod 30 and transmitted to the piston 20. The fluid in the cylinder 10 is compressed by the reciprocating motion of the piston 20.

[0015] 1 , the reciprocating compressor 3 includes a plain bearing 50 that rotatably supports the crankshaft 40. The plain bearing 50 forms an oil film of lubricating oil supplied from outside the plain bearing 50 in a bearing gap between the bearing surface of the plain bearing 50 and the outer circumferential surface of the crankshaft 40, and supports the crankshaft 40 via the oil film.

[0016] Next, the plain bearing 50 of the reciprocating compressor 3 will be described with reference to FIGS. 2A to 4B. FIG. 2A is a view of a crankshaft and plain bearing according to one embodiment, viewed from the axial direction of the crankshaft. FIG. 2B is an axial cross-sectional view of the crankshaft and plain bearing according to one embodiment, taken along the oil filler port. The hatching on the plain bearing indicates a cross-section of the main body portion (main body portion 62, described below) of the plain bearing. FIG. 3A is a schematic diagram showing a planar development of the bearing surface of a plain bearing according to one embodiment. FIG. 3B is a schematic diagram showing a planar development of the bearing surface of a plain bearing according to another embodiment. FIG. 4A is a view showing an embodiment in region A shown in FIG. 3B, illustrating the configuration of an oil drain groove and an oil pocket. FIG. 4B is a view showing another embodiment in region A shown in FIG. 3B, illustrating the configuration of an oil drain groove and an oil pocket.

[0017] In some embodiments, as shown in FIGS. 2A to 4B , the plain bearing 50 (50A, 50B) includes end faces 52 (54, 56) in the axial direction X1 of the plain bearing 50 (50A, 50B), and a bearing surface 200 formed between the end faces 52 (54, 56). The end face 52 includes a first end face 54 and a second end face 56 located on the opposite side of the first end face 54 in the axial direction X1. As shown in FIGS. 2A and 2B , the bearing surface 200 faces the outer peripheral surface 42 of the crankshaft 40 across a gap BC from the crankshaft 40. In this way, the bearing surface 200 is the inner surface of the plain bearing 50 (50A, 50B) in the radial direction X2 (the inner peripheral surface of the plain bearing 50).

[0018] The outer peripheral surface 58 of the plain bearing 50 (50A, 50B) is the outer surface of the plain bearing 50 (50A, 50B) in the radial direction X2. The plain bearing 50 (50A, 50B) has an oil supply hole 60 provided along the radial direction X2, and one end of the oil supply hole 60 opens to the outer peripheral surface 58 of the plain bearing 50. The other end of the oil supply hole 60 opens to the inner peripheral surface of the plain bearing 50 (50A, 50B) and forms an oil supply port 220, which will be described later.

[0019] In some embodiments, as shown in Figures 2A to 4B, the bearing surface 200 includes a circumferential groove 210 provided along the circumferential direction X3 of the bearing surface 200, an oil supply port 220 that opens into the circumferential groove 210, and at least one oil drain groove 230 (230A to 230D) that communicates with the circumferential groove 210.

[0020] 2B and 3A, the oil drain grooves 230 (230A to 230D) communicate directly with the circumferential groove 210. In another embodiment, as shown in FIGS. 3B to 4B, the oil drain grooves 230 (230A to 230D) communicate with the circumferential groove 210 via oil pockets 250 (250A to 250D), which will be described later.

[0021] As shown in FIGS. 2B to 3B, the circumferential groove 210 is provided over the entire circumference of the bearing surface 200 in the circumferential direction X3.

[0022] As described above, as shown in Fig. 2B , the oil filler port 220 is formed by one end of the oil fill hole 60 that opens into the inner circumferential surface of the plain bearing 50 (50A, 50B). The oil filler port 220 opens into the circumferential groove 210 in the inner circumferential surface of the plain bearing 50 (50A, 50B). In one embodiment, as shown in Fig. 2B , the oil filler port 220 is provided at the same vertical position H as the central axis O of the plain bearing 50 in the vertical direction X4.

[0023] In some embodiments, as shown in Figures 3A to 4B, the oil drain grooves 230 (230A to 230D) extend to the end faces 52 (54, 56) in the axial direction X1 of the plain bearing 50 (50A, 50B). In one embodiment, as shown in Figures 3A to 4B, the oil drain grooves 230 (230A to 230D) extend along the axial direction X1 of the plain bearing 50 (50A, 50B).

[0024] 2B to 4B , oil drain groove 230 (230A to 230D) communicates with circumferential groove 210 at a circumferential position θ that is different from that of oil filler port 220. In one embodiment, as shown in FIGS. 2B to 4B , when the circumferential position of oil filler port 220 on bearing surface 200 is θ=0°, oil drain groove 230 (230A to 230D) communicates with circumferential groove 210 at a circumferential position θ≠0°.

[0025] 2A to 4B, the oil drain groove 230 (230A to 230D) is provided in a region of the bearing surface 200 that is above the central axis O of the plain bearing 50 (50A, 50B) in the vertical direction X4. The entire oil drain groove 230 (230A to 230D) is located above the vertical position H.

[0026] The oil drain grooves 230 (230A to 230D) may be provided at multiple locations. The multiple oil drain grooves 230 (230A to 230D) may be provided at different axial positions, or may be distributed in the circumferential direction X3.

[0027] In some embodiments, as shown in FIGS. 3A and 3B , the multiple oil drain grooves 230 (230A to 230D) include a pair of oil drain grooves 230A, 230B (or 230C, 230D) provided on both sides of the circumferential groove 210 in the axial direction X1. The pair of oil drain grooves 230A, 230B (or 230C, 230D) is provided at the same circumferential position θ1 (or θ2) on the bearing surface 200. In the embodiment shown in FIGS. 3A and 3B , two pairs of oil drain grooves 230A to 230D are provided in the plain bearing 50 (50A, 50B). In other embodiments, the number of pairs of oil drain grooves provided in the plain bearing 50 is not particularly limited, and one pair of oil drain grooves or three or more pairs of oil drain grooves may be provided.

[0028] In some embodiments, as shown in FIGS. 2A to 3B , the multiple oil drain grooves 230 (230A to 230D) are each provided at a different circumferential position θ (θ1, θ2) on the bearing surface 200. Note that all of the multiple oil drain grooves 230 (230A to 230D) may be provided at different circumferential positions θ. Furthermore, some of the multiple oil drain grooves 230 (230A to 230D) may be the above-described pair of oil drain grooves 230A, 230B (or 230C, 230D). In the embodiment shown in FIGS. 3A and 3B , the multiple oil drain grooves 230A to 230D are each provided at two different circumferential positions θ1, θ2. In other embodiments, the multiple oil drain grooves 230 may be provided at three or more different circumferential positions θ.

[0029] 3B to 4B , the bearing surface 200 further includes at least one oil pocket 250 (250A to 250D) provided in an axial range between the oil drain groove 230 (230A to 230D) and the circumferential groove 210. The oil pocket 250 (250A to 250D) extends along the axial direction X1. The oil pocket 250 (250A to 250D) also includes one end 252 and another end 254 in the axial direction X1. The one end 252 of the oil pocket 250 (250A to 250D) communicates with the oil drain groove 230 (230A to 230D), and the other end 254 communicates with the circumferential groove 210.

[0030] In some embodiments, as shown in Figures 3B to 4B, one oil pocket 250 (250A to 250D) communicates with one oil drain groove 230 (230A to 230D). In other embodiments, one oil pocket 250 (250A to 250D) may communicate with multiple oil drain grooves 230 (230A to 230D).

[0031] In some embodiments, as shown in FIGS. 3B to 4B , with respect to the circumferential direction X3, when the circumferential position corresponding to the vertical position H is defined as θ=0° and the direction upward from the vertical position H is defined as positive, the oil pocket 250 (250A to 250D) communicates with the circumferential groove 210 when the circumferential position θ is in the range of 20°≦θ≦60°.

[0032] 3B , the oil pocket 250 (250A to 250D) is provided in a region of the bearing surface 200 that is above the central axis O of the plain bearing 50B (50) in the vertical direction X4. The entire oil pocket 250 (250A to 250D) is located above the vertical position H.

[0033] The oil pockets 250 (250A to 250D) configured as described above may be provided at multiple locations, similar to the above-described oil drain grooves 230 (230A to 230D). The multiple oil pockets 250 (250A to 250D) may be provided at different axial positions, or may be distributed in the circumferential direction X3.

[0034] In some embodiments, as shown in FIG. 3B , the multiple oil pockets 250 (250A to 250D) include a pair of oil pockets 250A, 250B (or 250C, 250D) provided on both sides of the circumferential groove 210 in the axial direction X1. The pair of oil pockets 250A, 250B (or 250C, 250D) is provided at the same circumferential position θ1 (or θ2) on the bearing surface 200. In the embodiment shown in FIG. 3B , two pairs of oil pockets 250A to 250D are provided in the plain bearing 50B (50). In other embodiments, the number of pairs of oil pockets provided in the plain bearing 50 is not particularly limited, and one pair of oil pockets or three or more pairs of oil pockets may be provided.

[0035] In some embodiments, as shown in FIG. 3B , the multiple oil pockets 250 (250A to 250D) are provided at different circumferential positions θ (θ1, θ2) on the bearing surface 200. Note that all of the multiple oil pockets 250 (250A to 250D) may be provided at different circumferential positions θ. Furthermore, some of the multiple oil pockets 250 (250A to 250D) may be the above-described pair of oil pockets 250A and 250B (or 250C and 250D). In the embodiment shown in FIG. 3B , the multiple oil pockets 250A to 250D are provided at two different circumferential positions θ1 and θ2. In other embodiments, the multiple oil pockets 250 may be provided at three or more different circumferential positions θ.

[0036] As described above, the oil drain groove 230 (230A to 230D) and the oil pocket 250 (250A to 250D) may be provided in the plain bearing 50 (50A, 50B). The relative arrangement and dimensional relationship between the oil drain groove 230 and the oil pocket 250 will be described below with reference to Figures 4A and 4B.

[0037] In some embodiments, oil pocket 250 is formed so as to have a larger cross-sectional area in the axial direction X1 than oil drain groove 230. In one embodiment, as shown in FIG. 4A , width W1 of oil pocket 250 satisfies the condition 1<(W1 / W2)≦30, where W2 is the width of oil drain groove 230. In other embodiments, one oil pocket 250 may communicate with n oil drain grooves 230. The number n of oil drain grooves 230 satisfies the condition n≦(W1 / W2).

[0038] In some embodiments, oil pocket 250 is formed to have a larger volume than oil drain groove 230. In one embodiment, as shown in Figures 4A and 4B, the length L1 of oil pocket 250 satisfies the condition L2 ≤ L1, where L2 is the length of oil drain groove 230.

[0039] 4A and 4B , the angle φ1 of the oil pocket 250 with respect to the axial direction X1 on the bearing surface 200 satisfies the condition of −15°≦φ1≦15°. Also, the angle φ2 of the oil drain groove 230 with respect to the axial direction X1 on the bearing surface 200 satisfies the condition of −15°≦φ2≦15°.

[0040] Next, the specific structure of a plain bearing 50 according to several embodiments will be described with reference to Figure 5. Note that, below, parts that are common to the configurations described above in Figures 1 to 4B are given the same reference numerals, and descriptions thereof will be omitted where appropriate. Figure 5 is a perspective view of a plain bearing according to one embodiment, and is a perspective cross-sectional view of the plain bearing taken along the axial direction.

[0041] 5 , the plain bearing 50 includes a main body 62 and a bearing layer 64 provided on the inner surface of the main body 62. There are no particular limitations on the materials forming the main body 62 and the bearing layer 64. The main body 62 is made of a metal that may be, for example, carbon steel. The bearing layer 64 is made of a metal that may be, for example, white metal.

[0042] In some embodiments, the cross-sectional shape of the circumferential groove 210 in the circumferential direction X3 is rectangular, as shown in Fig. 5. The cross-sectional shape of the circumferential groove 210 in the circumferential direction X3 is not particularly limited, and may be, for example, a cross-sectional shape defined by a polygon other than a rectangle, or a cross-sectional shape defined by a curve such as an arch or a semicircle. In some embodiments, as shown in Fig. 5, the circumferential groove 210 is formed so as to be deeper than the thickness of the bearing layer 64 of the plain bearing 50.

[0043] In some embodiments, the cross-sectional shape of oil drain groove 230 in axial direction X1 is arcuate, as shown in Fig. 5. The cross-sectional shape of oil drain groove 230 in axial direction X1 is not particularly limited, and may be, for example, a cross-sectional shape defined by a polygon such as a rectangle or a square, or a cross-sectional shape defined by a curve other than an arcuate shape.

[0044] In some embodiments, the cross-sectional shape of oil pocket 250 in the axial direction X1 is arcuate, as shown in Fig. 5. The cross-sectional shape of oil pocket 250 in the axial direction X1 is not particularly limited, and may be, for example, a cross-sectional shape defined by a polygon such as a rectangle or a square, or a cross-sectional shape defined by a curve other than an arcuate shape.

[0045] In some embodiments, as described above, the cross-sectional area of ​​oil pocket 250 in the axial direction X1 is larger than the cross-sectional area of ​​oil drain groove 230 in the axial direction X1. Alternatively, the volume of oil pocket 250 is larger than the volume of the oil drain groove. In one embodiment, as shown in FIG. 5 , the depth D1 of oil pocket 250 satisfies the condition D2<D1<D3. Here, D2 is the depth of oil drain groove 230, and D3 is the depth of circumferential groove 210.

[0046] Next, an oil supply system of the reciprocating compressor 3 including the sliding bearing 50 having the above configuration will be described with reference to Fig. 6. Note that, hereinafter, parts common to the configurations described above in Figs. 1 to 5 will be assigned the same reference numerals, and descriptions thereof will be omitted as appropriate. Fig. 6 is a schematic diagram showing an oil supply system in a reciprocating compressor according to one embodiment.

[0047] In some embodiments, as shown in FIG. 6 , the reciprocating compressor 3 includes an oil supply system 100 for supplying lubricating oil to the plain bearing 50. The oil supply system 100 is provided below the crankshaft 40 and includes an oil tank 110 for storing lubricating oil, an oil supply line 120 provided between the oil tank 110 and the plain bearing 50, and an oil supply pump 130 provided in the oil supply line 120. The oil supply system 100 also includes a recovery line 140 for recovering the lubricating oil to the oil tank 110. In one embodiment, as shown in FIG. 6 , the oil supply system 100 includes a strainer 150 and an oil filter 160 for removing impurities from the lubricating oil, and an oil cooler 170 for adjusting the temperature of the lubricating oil. The strainer 150, the oil filter 160, and the oil cooler 170 are provided in the oil supply line 120. A hydraulic pressure adjustment line 180 is connected to the oil supply line 120 between the downstream of the oil supply pump 130 and the oil tank 110. A hydraulic pressure adjustment valve 182 is provided in the oil pressure adjustment line 180 to adjust the pressure of the lubricating oil after it has been pressurized.

[0048] The lubricating oil stored in the oil tank 110 is pressurized by the oil supply pump 130 and supplied to the plain bearing 50 via the oil supply line 120. The lubricating oil supplied to the plain bearing 50 flows into the circumferential groove 210 via the oil supply hole 60 of the plain bearing 50 and is drawn from the circumferential groove 210 into the bearing clearance BC. Furthermore, if the bearing surface 200 includes an oil pocket 250, the lubricating oil flows from the circumferential groove 210 into the oil pocket 250 and is then drawn into the bearing clearance BC as the crankshaft 40 rotates. The lubricating oil drawn into the bearing clearance BC lubricates the bearing surface 200 as the crankshaft 40 rotates, and is then discharged from the plain bearing 50 via the oil drain groove 230. The lubricating oil discharged from the plain bearing 50 falls from the plain bearing 50 or is collected in the oil tank 110 via the collection line 140.

[0049] The lubricating oil supplied to the plain bearing 50 by the oil supply system 100 described above may be used in components of the reciprocating compressor 3 other than the plain bearing 50. Below, the cylinder 10 and the piston 20, the thrust bearing 70, and the mechanical seal 80 will be described as components in which the lubricating oil is used.

[0050] In some embodiments, as shown in Fig. 6 , the connecting rod 30 includes an internal flow passage 32 for guiding lubricating oil to the gap between the cylinder 10 and the piston 20. One end 34 of the internal flow passage 32 opens to the piston 20, and the other end 36 of the internal flow passage 32 opens to the crankshaft 40. As shown in Fig. 6 , the crankshaft 40 includes an internal flow passage 44 for guiding lubricating oil to the internal flow passage 32 of the connecting rod 30. One end 45 of the internal flow passage 44 opens to the connecting rod 30, and the other end 46 of the internal flow passage 44 opens to the plain bearing 50. A groove 47 is formed in the outer peripheral surface 42 of the crankshaft 40, and the other end 46 of the internal flow passage 44 opens to the groove 47.

[0051] A portion of the lubricating oil supplied to the plain bearing 50 flows from the oil supply port 220 of the plain bearing 50 into the internal flow passage 44 of the crankshaft 40, passes through the internal flow passage 32 of the connecting rod 30, and reaches the gap between the cylinder 10 and the piston 20. After lubricating the gap between the cylinder 10 and the piston 20, the lubricating oil is collected in the oil tank 110.

[0052] 6 , the reciprocating compressor 3 further includes a thrust bearing 70 that supports the crankshaft 40 in the axial direction X1. The thrust bearing 70 is provided adjacent to the plain bearing 50 in the axial direction X1. The plain bearing 50 adjacent to the thrust bearing 70 is configured such that at least one oil drain groove 230 (230A to 230D) extends to one of the end faces 52 (54, 56) that is located on the thrust bearing 70 side.

[0053] The lubricating oil discharged from the plain bearing 50 lubricates the thrust bearing 70 adjacent to the plain bearing 50 in the axial direction X1. The lubricating oil that has lubricated the thrust bearing 70 is collected in the oil tank 110.

[0054] 6, the reciprocating compressor 3 includes a mechanical seal 80 that is installed on the outer peripheral surface 42 of the crankshaft 40. The mechanical seal 80 is connected to an oil supply line 120.

[0055] The lubricating oil discharged from the sliding bearing 50 fills the seal structure of the mechanical seal 80 together with the lubricating oil supplied from the oil supply line 120. The lubricating oil is then recovered into the oil tank 110 via the recovery line 140.

[0056] The above-described reciprocating compressor 3 can be used as a compressor for the high-temperature heat pump device 1. Hereinafter, the reciprocating compressor 3 for the high-temperature heat pump device 1 according to several embodiments will be described with reference to Fig. 7. Fig. 7 is a schematic diagram of the high-temperature heat pump device according to one embodiment.

[0057] As shown in FIG. 7, the high-temperature heat pump device 1 ３ The refrigeration cycle 2 includes the above-mentioned reciprocating compressor 3 and a NH ３ The refrigeration cycle includes a condenser 5, an expansion valve 7, and an evaporator 8 provided in the refrigerant circulation path 4. The reciprocating compressor 3 compresses NH ３ The refrigerant is NH ３ The NH 4 discharged from the reciprocating compressor 3 is discharged into the refrigerant circulation path 4. The condenser 5 ３ Heat is exchanged between the refrigerant and the heated fluid F1 flowing through the heated fluid line 6. ３ The refrigerant is decompressed by the expansion valve 7. The evaporator 8 is ３ Heat exchange occurs between the refrigerant and a heat source fluid F2 flowing through a heat source fluid line 9. The heated fluid F1 is heated by heat exchange in the condenser 5. The heat source fluid F2 is cooled by heat exchange in the evaporator 8. The heated fluid F1 may be, for example, water. The heat source fluid F2 may be, for example, hot water.

[0058] In some embodiments, the evaporator 8 of the high-temperature heat pump device 1 is configured to mix the heat source fluid F2 at 60 degrees Celsius or higher and the liquid NH ３The high-temperature heat pump device 1 is configured to exchange heat with the refrigerant. ３ The saturation temperature of the refrigerant is the NH ３ If the temperature of the lubricating oil in the reciprocating compressor 3 is too low, the NH ３ The refrigerant may be condensed or dissolved in the lubricating oil. Therefore, the temperature of the lubricating oil of the reciprocating compressor 3 is ３ The temperature is adjusted to fall within a temperature range according to the saturation temperature of the refrigerant. ３ When the saturation temperature of the refrigerant is about 50 to 60 degrees Celsius, the temperature range of the lubricating oil for the reciprocating compressor 3 is set to 60 to 70 degrees Celsius.

[0059] The characteristic configurations of the sliding bearing 50 of the reciprocating compressor 3, the reciprocating compressor 3, and the reciprocating compressor 3 for the high-temperature heat pump device 1 according to the several embodiments described above can be summarized as follows.

[0060] [1] A plain bearing (50) of a reciprocating compressor (3) according to at least some embodiments includes: a first end face (54) in an axial direction (X1); a second end face (56) located on the opposite side of the first end face (54) in the axial direction (X1) from the first end face (54); and a bearing surface (200) formed between the first end face (54) and the second end face (56) and facing an outer peripheral surface (42) of a crankshaft (40) of the reciprocating compressor (3) across a gap (BC) between the crankshaft (40) and the bearing surface (200), wherein the bearing surface (200) includes: a circumferential groove (210) provided along a circumferential direction (X3) of the bearing surface (200); and an oil filler port (220) opening into the circumferential groove (210). and at least one oil drain groove (230; 230A to 230D) that communicates with the circumferential groove (210) at a circumferential position (θ) different from the oil filler port (220) and that extends to at least one of the first end face (54) or the second end face (56).

[0061] A reciprocating compressor (3) uses a plain bearing (50) to rotatably support a crankshaft (40). The plain bearing (50) forms an oil film of lubricating oil supplied from an external source in a bearing gap (BC) between a bearing surface (200) and the outer peripheral surface (42) of the crankshaft (40), and rotatably supports the crankshaft (40) via the oil film. In the plain bearing (50), an allowable temperature range capable of maintaining the reliability of the plain bearing (50) may be set in consideration of the temperature rise of the oil film caused by frictional heat accompanying the rotation of the crankshaft (40). To keep the oil film temperature within the allowable temperature range of the plain bearing (50), it is conceivable to supply fresh low-temperature lubricating oil from outside the plain bearing (50). However, some of the low-temperature lubricating oil may flow out of the plain bearing (50) without being effectively drawn into the bearing gap (BC), which may result in the oil film temperature not being kept within the allowable temperature range of the plain bearing (50). In this regard, according to the configuration [1], the oil drain groove (230; 230A-230D) is provided, which communicates with the circumferential groove (210) at a circumferential position (θ) different from the oil fill port (220) and extends to at least one of the end faces (52; 54, 56) of the plain bearing (50). This makes it possible to lengthen the main discharge path of the lubricating oil from the oil fill port (220) to the oil drain groove (230; 230A-230D) in the plain bearing (50). Therefore, the low-temperature lubricating oil supplied from the oil fill port (220) is more likely to be drawn into the bearing clearance (BC) before being discharged from the plain bearing (50) via the oil drain groove (230; 230A-230D). This makes it possible to increase the amount of low-temperature lubricating oil supplied to the bearing clearance (BC), thereby suppressing the temperature rise of the oil film.

[0062] [2] In some embodiments, in the configuration of [1] above, at least one oil drain groove (230; 230A to 230D) is provided in a region of the bearing surface (200) above the central axis (O) of the sliding bearing (50) in the vertical direction (X4).

[0063] In the plain bearing (50) of the reciprocating compressor (3), a load is concentrated on a region of the bearing surface (200) below the central axis (O) of the plain bearing (50) in the vertical direction (X4). According to the configuration [2] above, by arranging the oil drain grooves (230; 230A to 230D) so as to avoid the lower region of the bearing surface (200) where the load is concentrated, it is possible to suppress a decrease in the load capacity of the plain bearing (50) caused by a decrease in oil film pressure accompanying the formation of the oil drain grooves (230; 230A to 230D).

[0064] [3] In some embodiments, in the configuration of [1] or [2] above, at least one oil drain groove (230; 230A to 230D) includes a pair of oil drain grooves (230; 230A to 230D) provided on both sides of the circumferential groove (210) in the axial direction (X1) so as to extend to the first end face (54) and the second end face (56), respectively.

[0065] According to the configuration [3] above, a pair of oil drain grooves (230; 230A to 230D) are provided that each communicate with the circumferential groove (210) at a circumferential position (θ) different from the oil fill port (220) and each extend to both end faces (52; 54, 56) of the plain bearing (50). This makes it possible to lengthen the main discharge path of lubricating oil from the oil fill port (220) in the plain bearing (50) to the oil drain grooves (230; 230A to 230D) on both sides of the circumferential groove (210) in the axial direction (X1). Therefore, low-temperature lubricating oil supplied from the oil fill port (220) is likely to be drawn into the bearing gaps (BC) on both sides of the circumferential groove (210) in the axial direction (X1) before being discharged from the plain bearing (50) via the oil drain grooves (230; 230A to 230D). This allows for more effective supply of low-temperature lubricating oil to the bearing gap (BC), thereby further suppressing the temperature rise of the oil film.

[0066] [4] In some embodiments, in any of the configurations [1] to [3] above, at least one oil drain groove (230; 230A to 230D) includes a plurality of oil drain grooves (230; 230A to 230D) that are provided at different circumferential positions (θ) on the bearing surface (200) so as to extend to at least one of the first end face (54) or the second end face (56).

[0067] According to the configuration [4] above, since a plurality of oil drain grooves (230; 230A to 230D) are provided at different circumferential positions (θ) on the bearing surface (200), the path taken by the lubricating oil drawn into the bearing clearance (BC) to the oil drain grooves can be shortened. This makes it possible to drain the lubricating oil from the sliding bearing (50) before the temperature of the lubricating oil in the bearing clearance (BC) rises excessively, thereby suppressing the maximum temperature of the oil film.

[0068] [5] In some embodiments, in the configuration of any of the above items [1] to [4], the bearing surface (200) includes at least one oil pocket (250; 250A to 250D) provided in an axial range between each of the at least one oil drain groove (230; 230A to 230D) and the circumferential groove (210), and each of the at least one oil drain groove (230; 230A to 230D) communicates with one end (252) of the at least one oil pocket (250; 250A to 250D) in the axial direction (X1), and the circumferential groove (210) communicates with the other end (254) of the at least one oil pocket (250; 250A to 250D) in the axial direction (X1) at a circumferential position (θ) different from the oil fill port (220).

[0069] According to the configuration [5] above, the oil pocket (250; 250A to 250D) is provided so that one end (252) in the axial direction (X1) communicates with the oil drain groove (230; 230A to 230D) and the other end (254) in the axial direction (X1) communicates with the circumferential groove (210) at a circumferential position (θ) different from the oil fill port (220). Therefore, low-temperature lubricating oil supplied from the oil fill port (220) passes through the oil pocket (250; 250A to 250D) before being discharged from the sliding bearing (50) via the oil drain groove (230; 230A to 230D). In the oil pockets (250; 250A-250D), the low-temperature lubricating oil that has flowed into the oil pockets (250; 250A-250D) and the lubricating oil that has lubricated the bearing surface (200) are replaced with each other as the crankshaft (40) rotates. As the crankshaft (40) rotates, the low-temperature lubricating oil is drawn from the oil pockets (250; 250A-250D) into the bearing gap (BC) and lubricates the bearing surface (200). This makes it possible to further increase the amount of low-temperature lubricating oil supplied to the bearing gap (BC), thereby further suppressing the temperature rise of the oil film.

[0070] [6] A reciprocating compressor (3) according to at least some embodiments comprises: a crankshaft (40); a thrust bearing (70) that supports the crankshaft (40) in an axial direction (X1); and a plain bearing (50) having any of the configurations described in [1] to [5] above, that rotatably supports the crankshaft (40) and is provided adjacent to the thrust bearing (70) in the axial direction (X1), wherein at least one oil drain groove (230; 230A to 230D) extends to an end face (52; 54, 56) of the first end face (54) or the second end face (56) that is located on the thrust bearing side.

[0071] According to the configuration [6] above, the oil drain groove (230; 230A to 230D) extends to one end face (52; 54, 56) of the plain bearing (50) located on the thrust bearing (70) side, and the lubricating oil discharged from the oil drain groove (230; 230A to 230D) can be used to cool the thrust bearing (70), thereby suppressing a decrease in the operating efficiency of the reciprocating compressor (3).

[0072] [7] A reciprocating compressor (3) for a high-temperature heat pump device (1) according to at least some embodiments includes: a crankshaft (40); and a plain bearing (50) having any of the configurations described in [1] to [5] above, which rotatably supports the crankshaft (40).

[0073] As described in [1] above, in the sliding bearing (50) of the reciprocating compressor (3), an allowable temperature range that can maintain the reliability of the sliding bearing (50) may be set in consideration of the temperature rise of the oil film caused by frictional heat accompanying the rotation of the crankshaft (40). To more reliably keep the oil film temperature within the allowable temperature range of the sliding bearing (50), it is possible to lower the temperature of the oil supplied from outside the sliding bearing (50). However, in the reciprocating compressor (3) for the high-temperature heat pump device (1), excessively lowering the temperature of the oil supplied from outside the sliding bearing (50) may cause condensation of the refrigerant circulating through the refrigeration cycle (2) of the high-temperature heat pump device (1) or a decrease in the viscosity of the lubricating oil due to an increase in the amount of refrigerant dissolved in the lubricating oil. Thus, there is a limit to how much the oil supply temperature can be lowered in the reciprocating compressor (3) for the high-temperature heat pump device (1). In this regard, according to the configuration [7], the oil drain groove (230; 230A-230D) is provided, which communicates with the circumferential groove (210) at a circumferential position (θ) different from the oil fill port (220) and extends to at least one of the end faces (52; 54, 56) of the plain bearing (50). This lengthens the main drain path of the lubricating oil from the oil fill port (220) to the oil drain groove (230; 230A-230D) in the plain bearing (50). Therefore, the low-temperature lubricating oil supplied from the oil fill port (220) is more likely to be drawn into the bearing clearance (BC) before being discharged from the plain bearing (50) via the oil drain groove (230; 230A-230D). This makes it possible to increase the amount of low-temperature lubricating oil supplied to the bearing clearance (BC), thereby suppressing the temperature rise of the oil film without excessively lowering the supply temperature of the lubricating oil.

[0074] Although several embodiments of the present invention have been described above, it is of course possible to add modifications to the above-described embodiments without departing from the spirit of the present invention.

[0075] In this specification, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions expressing that things are in an equal state, such as "identical," "equal," and "homogeneous," not only express a state in which there is a strict equivalence, but also express a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions expressing shapes such as a rectangular shape or a cylindrical shape not only express shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0076] DESCRIPTION OF SYMBOLS 1: High temperature heat pump device 3: Reciprocating compressor 40: Crankshaft 42: Outer circumferential surface 50: Slide bearing 52: End surface 54: First end surface 56: Second end surface 70: Thrust bearing 200: Bearing surface 210: Circumferential groove 220: Oil supply port 230 (230A to 230D): Oil drain groove 250 (250A to 250D): Oil pocket 252: One end 254: Other end BC: Clearance (bearing clearance) O: Central axis X1: Axial direction X3: Circumferential direction X4: Vertical direction θ: Circumferential position

Claims

1. A plain bearing for a reciprocating compressor, comprising: a first end face in the axial direction; a second end face located on the opposite side of the first end face in the axial direction; and a bearing surface formed between the first end face and the second end face, facing the outer peripheral surface of the crankshaft of the reciprocating compressor across a gap between the crankshaft and the bearing surface, wherein the bearing surface includes: a circumferential groove provided along the circumferential direction of the bearing surface; an oil supply port opening into the circumferential groove; and at least one oil drain groove communicating with the circumferential groove at a circumferential position different from the oil supply port and extending to at least one of the first end face or the second end face.

2. A plain bearing for a reciprocating compressor according to claim 1, wherein the at least one oil drain groove is provided in a region of the bearing surface that is above the central axis of the plain bearing in the vertical direction.

3. A sliding bearing for a reciprocating compressor as described in claim 1 or 2, wherein the at least one oil drain groove includes a pair of oil drain grooves provided on both sides of the circumferential groove in the axial direction, extending to the first end face and the second end face, respectively.

4. A sliding bearing for a reciprocating compressor as described in claim 1 or 2, wherein the at least one oil drain groove includes a plurality of oil drain grooves provided at different circumferential positions on the bearing surface so as to extend to at least one of the first end face or the second end face.

5. A sliding bearing for a reciprocating compressor as set forth in claim 1 or 2, wherein the bearing surface includes at least one oil pocket provided in an axial range between each of the at least one oil drain groove and the circumferential groove, and each of the at least one oil drain groove communicates with one axial end of the at least one oil pocket, and the circumferential groove communicates with the other axial end of the at least one oil pocket at a circumferential position different from the oil supply port.

6. A reciprocating compressor comprising: a crankshaft; a thrust bearing that supports the crankshaft in the axial direction; and a plain bearing according to claim 1 or 2 that rotatably supports the crankshaft and is provided adjacent to the thrust bearing in the axial direction, wherein the at least one oil drain groove extends to either the first end face or the second end face which is located on the thrust bearing side.

7. A reciprocating compressor for a high-temperature heat pump device, comprising: a crankshaft; and the sliding bearing according to claim 1 or 2, which rotatably supports the crankshaft.

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