Plain bearings for reciprocating compressors, reciprocating compressors, and reciprocating compressors for high-temperature heat pump systems.

Abstract

The present invention provides a sliding bearing for a reciprocating compressor, a reciprocating compressor, and a reciprocating compressor for a high-temperature heat pump system, which can suppress the temperature rise of the oil film by increasing the amount of low-temperature lubricating oil supplied to the bearing gap. [Solution] The sliding bearing of a reciprocating compressor 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, and a bearing surface formed between the first and second end faces and facing the outer circumferential surface of the crankshaft with a gap between it and the crankshaft of the reciprocating compressor. 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 that communicates with the circumferential groove at a circumferential position different from the oil supply port and extends to at least one of the first or second end face.

Description

Technical Field

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

Background Art

[0002] Conventionally, in a reciprocating compressor, a sliding bearing is used to rotatably support a crankshaft. The sliding bearing forms an oil film of lubricating oil supplied from the outside in a bearing gap between a bearing surface and an outer peripheral surface of the crankshaft, and rotatably supports the crankshaft through the oil film.

[0003] For example, Patent Document 1 describes a sliding bearing of a screw compressor, not a sliding bearing of a reciprocating compressor. Lubricating oil is supplied from an oil supply hole provided in the bearing surface of the sliding bearing, and the shaft of the screw rotor is rotatably supported through the oil film of the lubricating oil.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the sliding bearing of a reciprocating compressor, due to the temperature rise of the oil film caused by the frictional heat accompanying the rotation of the crankshaft, the reliability of the sliding bearing may decrease. Therefore, an allowable temperature range for maintaining the reliability of the sliding bearing may be set. In order to keep the oil film temperature within the allowable temperature range of the sliding bearing, it is conceivable to newly supply low-temperature lubricating oil from the outside of the sliding bearing.

[0006] However, some of the newly supplied low-temperature lubricant may not be effectively drawn into the bearing gap and may leak out of the sliding bearing, potentially failing to suppress the rise in oil film temperature and preventing the oil film temperature from remaining within the sliding bearing's allowable temperature range.

[0007] Furthermore, in the screw compressor described in Patent Document 1, the bearing surface of the sliding bearing has oil grooves extending to both axial ends of the sliding bearing, located at the same circumferential position as the oil supply holes. As a result, new lubricating oil supplied from the oil supply holes is not effectively drawn into the bearing gap, but easily flows out of the sliding bearing through 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 the temperature rise of the oil film by increasing the amount of low-temperature lubricating oil supplied to the bearing gap. [Means for solving the problem]

[0009] The sliding bearings of a reciprocating compressor according to at least some embodiments of the present invention are The first end face in the axial direction, The second end face is located on the opposite side in the axial direction from the first end face, A bearing surface formed between the first end face and the second end face, facing the outer circumferential surface of the crankshaft with a gap between it and the crankshaft of the reciprocating compressor, Equipped with, The bearing surface is A circumferential groove is provided along the circumferential direction of the bearing surface, A fuel inlet opening into the circumferential groove, At least one drain groove that communicates with a circumferential groove at a circumferential position different from the fuel filler opening and extends to at least one of the first end face or the second end face, Includes. [Effects of the Invention]

[0010] In at least some embodiments of the present invention, an oil drain groove is provided that communicates with a circumferential groove at a circumferential position different from the oil inlet and extends to at least one of the axial end faces of the sliding bearing. This allows the main discharge path of lubricating oil from the oil inlet to the oil drain groove in the sliding bearing to be lengthened. As a result, the low-temperature lubricating oil supplied from the oil inlet is more easily drawn into the bearing gap before being discharged from the sliding bearing via the oil drain groove. Therefore, it is possible to increase the amount of low-temperature lubricating oil supplied to the bearing gap, thereby suppressing the temperature rise of the oil film. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a reciprocating compressor according to one embodiment. [Figure 2A] This is a diagram showing a crankshaft and a sliding bearing according to one embodiment, viewed from the axial direction of the crankshaft. [Figure 2B] This is an axial cross-sectional view of a crankshaft and a sliding bearing according to one embodiment, and is a cross-sectional view obtained by cutting the crankshaft and sliding bearing at the position of the lubrication port. [Figure 3A] This is a schematic diagram showing the bearing surface of a sliding bearing according to one embodiment unfolded into a plane. [Figure 3B] This is a schematic diagram showing the bearing surface of a sliding bearing according to another embodiment unfolded into a plane. [Figure 4A] Figure 3B shows one embodiment in region A, illustrating the configuration of the oil drain channel and oil pocket. [Figure 4B] Figure 3B shows another embodiment in region A, illustrating the configuration of the oil drain channel and oil pocket. [Figure 5] This is a perspective view of a sliding bearing according to one embodiment, and is a perspective cross-sectional view of the sliding bearing cut along the axial direction. [Figure 6] This is a schematic diagram showing the lubrication system in a reciprocating compressor according to one embodiment. [Figure 7] This is a schematic diagram of a high-temperature heat pump device according to one embodiment. [Modes for carrying out the invention]

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

[0013] First, referring to FIG. 1, the configuration of a reciprocating compressor according to some embodiments will be described. FIG. 1 is a schematic diagram of a reciprocating compressor according to an embodiment.

[0014] As shown in FIG. 1, the reciprocating compressor 3 includes a cylinder 10, a piston 20 for compressing the fluid in the cylinder 10, and a crankshaft 40 connected to the piston 20 via a connecting rod 30. The crankshaft 40 rotates about the central axis O of the crankshaft 40 as the rotation axis. The rotational motion of the crankshaft 40 is converted into a 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] In some embodiments, as shown in FIG. 1, the reciprocating compressor 3 includes a sliding bearing 50 that rotatably supports the crankshaft 40. The sliding bearing 50 forms an oil film of lubricating oil supplied from the outside of the sliding bearing 50 in the bearing gap between the bearing surface of the sliding bearing 50 and the outer peripheral surface of the crankshaft 40, and supports the crankshaft 40 through the oil film.

[0016] Subsequently, referring to FIGS. 2A to 4B, the sliding bearing 50 of the reciprocating compressor 3 will be described. FIG. 2A is a view of a crankshaft and a sliding bearing according to an embodiment as viewed from the axial direction of the crankshaft. FIG. 2B is a cross-sectional view in the axial direction of a crankshaft and a sliding bearing according to an embodiment, and is a cross-sectional view obtained by cutting the crankshaft and the sliding bearing at the position of the oil supply port. Note that the hatching attached to the sliding bearing indicates the cross-section of the main body portion (main body 62 described later) of the sliding bearing. Figure 3A is a schematic diagram showing the bearing surface of a sliding bearing according to one embodiment unfolded on a plane. Figure 3B is a schematic diagram showing the bearing surface of a sliding bearing according to another embodiment unfolded on a plane. Figure 4A is a diagram showing one embodiment in region A shown in Figure 3B, illustrating the configuration of the oil drain channel and oil pocket. Figure 4B is a diagram showing another embodiment in region A shown in Figure 3B, illustrating the configuration of the oil drain channel and oil pocket.

[0017] In some embodiments, as shown in Figures 2A to 4B, the sliding bearing 50 (50A, 50B) includes end faces 52 (54, 56) in the axial direction X1 of the sliding 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 Figures 2A and 2B, the bearing surface 200 faces the outer circumferential surface 42 of the crankshaft 40, with a gap BC between them. Thus, the bearing surface 200 is the inner surface of the sliding bearing 50 (50A, 50B) in the radial direction X2 (the inner circumferential surface of the sliding bearing 50).

[0018] The outer circumferential surface 58 of the sliding bearing 50 (50A, 50B) is the outer surface in the radial direction X2 of the sliding bearing 50 (50A, 50B). The sliding 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 onto the outer circumferential surface 58 of the sliding bearing 50. The other end of the oil supply hole 60 opens onto the inner circumferential surface of the sliding 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 opening into the circumferential groove 210, and at least one oil drain groove 230 (230A to 230D) communicating with the circumferential groove 210.

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

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

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

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

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

[0025] In some embodiments, as shown in Figures 2A to 4B, the oil drain grooves 230 (230A to 230D) are provided in the bearing surface 200 in a region above the central axis O of the sliding bearings 50 (50A, 50B) in the vertical direction X4. The entirety of the oil drain grooves 230 (230A to 230D) is located above the vertical position H.

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

[0027] In some embodiments, as shown in Figures 3A and 3B, the plurality of drain grooves 230 (230A to 230D) include a pair of drain grooves 230A, 230B (or 230C, 230D) provided on both sides of the circumferential groove 210 in the axial direction X1. The pair of drain grooves 230A, 230B (or 230C, 230D) are provided at the same circumferential position θ1 (or θ2) on the bearing surface 200. In the embodiments shown in Figures 3A and 3B, two pairs of oil drain grooves 230A to 230D are provided in the sliding bearing 50 (50A, 50B). In other embodiments, the number of pairs of oil drain grooves provided in the sliding 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 Figures 2A to 3B, the multiple oil drain grooves 230 (230A to 230D) are provided at different circumferential positions θ (θ1, θ2) on the bearing surface 200. It is also possible that all of the multiple oil drain grooves 230 (230A to 230D) are provided at mutually different circumferential positions θ. Furthermore, some of the multiple oil drain grooves 230 (230A to 230D) may be the aforementioned pair of oil drain grooves 230A, 230B (or 230C, 230D). In the embodiments shown in Figures 3A and 3B, the multiple oil drain grooves 230A to 230D are provided at two different circumferential positions θ1 and θ2, respectively. In other embodiments, the multiple oil drain grooves 230 may be provided at three or more different circumferential positions θ, respectively.

[0029] In some embodiments, as shown in Figures 3B to 4B, the bearing surface 200 further includes at least one oil pocket 250 (250A to 250D) provided in the 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. Furthermore, the oil pockets 250 (250A to 250D) include one end 252 and the other end 254 in the axial direction X1. One end 252 of the oil pockets 250 (250A to 250D) communicates with the oil drain grooves 230 (230A to 230D), and the other end 254 communicates with the circumferential grooves 210.

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

[0031] In some embodiments, as shown in Figures 3B to 4B, if the circumferential position corresponding to the vertical position H is set to θ = 0° in the circumferential direction X3, and the direction upward from the vertical position H is considered positive, then the oil pockets 250 (250A to 250D) communicate with the circumferential grooves 210 when the circumferential position θ is in the range of 20° ≤ θ ≤ 60°.

[0032] In some embodiments, as shown in Figure 3B, the oil pockets 250 (250A to 250D) are provided in a region of the bearing surface 200 that is above the central axis O of the sliding bearing 50B (50) in the vertical direction X4. The entirety of the oil pockets 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 oil drain grooves 230 (230A to 230D) described above. The multiple oil pockets 250 (250A to 250D) may be provided at different axial positions, or they may be distributed in the circumferential direction X3.

[0034] In some embodiments, as shown in Figure 3B, the plurality of 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) are provided at the same circumferential position θ1 (or θ2) on the bearing surface 200. In the embodiment shown in Figure 3B, two pairs of oil pockets 250A to 250D are provided in the sliding bearing 50B (50). In other embodiments, the number of pairs of oil pockets provided in the sliding 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 Figure 3B, the multiple oil pockets 250 (250A to 250D) are provided at different circumferential positions θ (θ1, θ2) on the bearing surface 200. It is also possible that all of the multiple oil pockets 250 (250A to 250D) are provided at mutually different circumferential positions θ. Furthermore, some of the multiple oil pockets 250 (250A to 250D) may be the aforementioned pair of oil pockets 250A, 250B (or 250C, 250D). In the embodiment shown in Figure 3B, the oil pockets 250A to 250D are provided at two different circumferential positions θ1 and θ2, respectively. In other embodiments, the oil pockets 250 may be provided at three or more different circumferential positions θ, respectively.

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

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

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

[0039] In some embodiments, as shown in Figures 4A and 4B, the angle φ1 of the oil pocket 250 with respect to the axial X1 on the bearing surface 200 satisfies the condition -15° ≤ φ1 ≤ 15°. Also, the angle φ2 of the oil drain groove 230 with respect to the axial X1 on the bearing surface 200 satisfies the condition -15° ≤ φ2 ≤ 15°.

[0040] Next, with reference to Figure 5, the specific structures of several embodiments of the sliding bearing 50 will be described. In the following, parts common to the configuration described above in Figures 1 to 4B will be denoted by the same reference numerals, and explanations will be omitted where appropriate. Figure 5 is a perspective view of a sliding bearing according to one embodiment, and is a perspective cross-sectional view of the sliding bearing cut along the axial direction.

[0041] In some embodiments, as shown in Figure 5, the sliding bearing 50 includes a body portion 62 and a bearing layer 64 provided on the inner surface of the body portion 62. The materials forming the body portion 62 and the bearing layer 64 are not particularly limited. The body portion 62 is made of a metal, which may be, for example, carbon steel. The bearing layer 64 is made of a metal, which may be, for example, white metal.

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

[0043] In some embodiments, as shown in Figure 5, the cross-sectional shape of the oil drain groove 230 in the axial direction X1 is arched. The cross-sectional shape of the oil drain groove 230 in the axial direction X1 is not particularly limited and may be 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 arch.

[0044] In some embodiments, as shown in Figure 5, the cross-sectional shape of the oil pocket 250 in the axial direction X1 is arc-shaped. The cross-sectional shape of the oil pocket 250 in the axial direction X1 is not particularly limited and may be 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 arc.

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

[0046] Subsequently, referring to FIG. 6, the oil supply system of the reciprocating compressor 3 including the sliding bearing 50 having the above configuration will be described. In the following, for the parts common to the configuration described above in FIGS. 1 to 5, the same reference numerals will be given and the description will be omitted as appropriate. FIG. 6 is a schematic diagram showing an oil supply system in a reciprocating compressor according to an 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 sliding bearing 50. The oil supply system 100 includes an oil tank 110 provided below the crankshaft 40 for storing lubricating oil, an oil supply line 120 provided between the oil tank 110 and the sliding bearing 50, and an oil supply pump 130 provided in the oil supply line 120. Further, the oil supply system 100 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. An oil 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. An oil pressure adjustment valve 182 for adjusting the pressure after boosting the lubricating oil is provided in the oil pressure adjustment line 180.

[0048] The lubricating oil stored in the oil tank 110 is boosted by the oil supply pump 130 and supplied to the sliding bearing 50 through the oil supply line 120. Lubricating oil supplied to the sliding bearing 50 flows into the circumferential groove 210 through the oil supply hole 60 of the sliding bearing 50 and is drawn from the circumferential groove 210 into the bearing clearance BC. Also, 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 sliding bearing 50 through the oil drain groove 230. The lubricating oil discharged from the sliding bearing 50 is collected in the oil tank 110 either by falling from the sliding bearing 50 or by passing through the recovery line 140.

[0049] The lubricating oil supplied to the sliding bearing 50 by the above-described lubrication system 100 may also be used in other components of the reciprocating compressor 3 besides the sliding bearing 50. The following describes components in which the lubricating oil is used, including the cylinder 10 and piston 20, the thrust bearing 70, and the mechanical seal 80.

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

[0051] A portion of the lubricating oil supplied to the sliding bearing 50 flows from the oil inlet 220 of the sliding bearing 50 into the internal passage 44 of the crankshaft 40, passes through the internal 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] In some embodiments, as shown in Figure 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 sliding bearing 50 in the axial direction X1. The sliding bearing 50 adjacent to the thrust bearing 70 is configured such that at least one oil drain groove 230 (230A to 230D) extends to the end face 52 (54, 56) located on the thrust bearing 70 side.

[0053] The lubricating oil discharged from the sliding bearing 50 lubricates the thrust bearing 70 adjacent to the sliding 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] The reciprocating compressor 3 includes a mechanical seal 80 installed on the outer circumferential surface 42 of the crankshaft 40, as shown in Figure 6. The mechanical seal 80 is connected to the lubrication line 120.

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

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

[0057] As shown in Figure 7, the high-temperature heat pump device 1 includes a refrigeration cycle 2 in which NH3 refrigerant is circulated. The refrigeration cycle 2 includes the reciprocating compressor 3 described above, and a condenser 5, expansion valve 7, and evaporator 8, which are provided together with the reciprocating compressor 3 in the NH3 refrigerant circulation path 4, as components of the refrigeration cycle. The reciprocating compressor 3 discharges compressed NH3 refrigerant into the NH3 refrigerant circulation path 4. The condenser 5 exchanges heat between the NH3 refrigerant discharged from the reciprocating compressor 3 and the fluid to be heated F1 flowing through the fluid to be heated line 6. The NH3 refrigerant that has passed through the condenser 5 is depressurized by the expansion valve 7. The evaporator 8 exchanges heat between the depressurized NH3 refrigerant and the heat source fluid F2 flowing through the heat source fluid line 9. The fluid to be heated F1 is heated by the heat exchange in the condenser 5. The heat source fluid F2 is cooled by the heat exchange in the evaporator 8. The fluid to be heated F1 may be, for example, water. The heat source fluid F2 may also be, for example, hot water.

[0058] In some embodiments, the evaporator 8 of the high-temperature heat pump device 1 is configured to exchange heat between a heat source fluid F2 at a temperature of 60 degrees Celsius or higher and a liquid NH3 refrigerant. The saturation temperature of the NH3 refrigerant in the high-temperature heat pump device 1 is higher than that of the NH3 refrigerant in a typical heat pump device. If the temperature of the lubricating oil in the reciprocating compressor 3 is excessively low, condensation or dissolution of the NH3 refrigerant into the lubricating oil may occur due to the circulation of the lubricating oil as described above. Therefore, the temperature of the lubricating oil in the reciprocating compressor 3 is adjusted to fall within a temperature range corresponding to the saturation temperature of the NH3 refrigerant. For example, if the saturation temperature of the NH3 refrigerant is around 50 to 60 degrees Celsius, the temperature range of the lubricating oil in 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 some of the embodiments described above are summarized as follows.

[0060] [1] The sliding bearing (50) of a reciprocating compressor (3) according to at least some embodiments is The first end face (54) in the axial direction (X1), The first end face (54) is located opposite to the second end face (56) in the axial direction (X1), A bearing surface (200) is formed between the first end face (54) and the second end face (56), and faces the outer circumferential surface (42) of the crankshaft (40) of the reciprocating compressor (3) with a gap (BC) between the crankshaft (40) and the bearing surface (200), Equipped with, The bearing surface (200) is A circumferential groove (210) is provided along the circumferential direction (X3) of the bearing surface (200), A fuel inlet (220) opens into the circumferential groove (210), At least one drain groove (230; 230A~230D) is connected to the circumferential groove (210) at a circumferential position (θ) different from the fuel filler port (220) and extends to at least one of the first end face (54) or the second end face (56), Includes.

[0061] In a reciprocating compressor (3), a sliding bearing (50) is used to rotatably support the crankshaft (40). The sliding bearing (50) forms an oil film of lubricating oil supplied from the outside in the bearing gap (BC) between the bearing surface (200) and the outer circumferential surface (42) of the crankshaft (40), and rotatably supports the crankshaft (40) through the oil film. In the sliding bearing (50), a permissible temperature range that can maintain the reliability of the sliding bearing (50) may be set, taking into account the temperature rise of the oil film due to frictional heat generated by the rotation of the crankshaft (40). To keep the oil film temperature within the permissible temperature range of the sliding bearing (50), it is conceivable to supply new, low-temperature lubricating oil from outside the sliding bearing (50). However, some of the low-temperature lubricating oil may not be effectively drawn into the bearing gap (BC) and may leak out of the sliding bearing (50), so there is a risk that the oil film temperature cannot be kept within the permissible temperature range of the sliding bearing (50). In this regard, according to the configuration described in [1] above, an oil drain groove (230; 230A~230D) is provided that communicates with the circumferential groove (210) at a circumferential position (θ) different from the oil inlet (220) and extends to at least one of the end faces (52; 54, 56) of the sliding bearing (50). This makes it possible to lengthen the main discharge path of lubricating oil from the oil inlet (220) to the oil drain groove (230; 230A~230D) in the sliding bearing (50). As a result, the low-temperature lubricating oil supplied from the oil inlet (220) is more easily drawn into the bearing gap (BC) before being discharged from the sliding bearing (50) via the oil drain groove (230; 230A~230D). Therefore, it becomes possible to increase the amount of low-temperature lubricating oil supplied to the bearing gap (BC), thereby suppressing the temperature rise of the oil film.

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

[0063] In the sliding bearing (50) of the reciprocating compressor (3), the load is concentrated in the region of the bearing surface (200) below the central axis (O) of the sliding bearing (50) in the vertical direction (X4). According to the configuration described in [2] above, by arranging the drainage grooves (230; 230A~230D) to avoid the lower region of the bearing surface (200) where the load is concentrated, it is possible to suppress the reduction in the load capacity of the sliding bearing (50) caused by the decrease in oil film pressure associated with the formation of the drainage grooves (230; 230A~230D).

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

[0065] According to the configuration described in [3] above, a pair of drain grooves (230; 230A~230D) are provided that communicate with the circumferential groove (210) at a circumferential position (θ) different from the oil inlet (220) and extend to both end faces (52; 54, 56) of the sliding bearing (50). As a result, the main discharge path of lubricating oil from the oil inlet (220) to the drain grooves (230; 230A~230D) in the sliding bearing (50) can be lengthened on both sides of the circumferential groove (210) in the axial direction (X1). Therefore, the low-temperature lubricating oil supplied from the oil inlet (220) is more easily drawn into the bearing gap (BC) on both sides of the circumferential groove (210) in the axial direction (X1) before being discharged from the sliding bearing (50) via the drain grooves (230; 230A~230D). Therefore, it becomes possible to more effectively supply low-temperature lubricating oil to the bearing gap (BC), and the temperature rise of the oil film can be further suppressed.

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

[0067] According to the configuration described in [4] above, multiple drainage grooves (230; 230A~230D) are provided at different circumferential positions (θ) on the bearing surface (200), thus shortening the path of lubricating oil drawn into the bearing gap (BC) to the drainage grooves. Therefore, it becomes possible to discharge the lubricating oil from the sliding bearing (50) before the temperature of the lubricating oil in the bearing gap (BC) rises excessively, thereby suppressing the maximum temperature of the oil film.

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

[0069] According to the configuration described in [5] above, an oil pocket (250; 250A~250D) is provided such that one end (252) in the axial direction (X1) communicates with an oil drain groove (230; 230A~230D), and the other end (254) in the axial direction (X1) communicates with a circumferential groove (210) at a circumferential position (θ) different from the oil inlet (220). As a result, the low-temperature lubricating oil supplied from the oil inlet (220) passes through the oil pocket (250; 250A~250D) before being discharged from the sliding bearing (50) via the oil drain groove (230; 230A~230D). In the oil pockets (250; 250A~250D), the low-temperature lubricating oil that flows into the oil pockets (250; 250A~250D) and the lubricating oil that lubricates the bearing surface (200) are exchanged 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). Therefore, it becomes possible to increase the amount of low-temperature lubricating oil supplied to the bearing gap (BC), and the temperature rise of the oil film can be further suppressed.

[0070] [6] Reciprocating compressors (3) according to at least some embodiments include: Crank axle (40) and, A thrust bearing (70) supports the crankshaft (40) in the axial direction (X1), A sliding bearing (50) having any of the configurations [1] to [5] above is provided adjacent to the thrust bearing (70) in the axial direction (X1) and rotatably supports the crankshaft (40), Equipped with, At least one drain groove (230; 230A to 230D) extends to the end face (52; 54, 56) of the first end face (54) or the second end face (56) located on the thrust bearing side.

[0071] According to the configuration described in [6] above, the oil drain groove (230; 230A~230D) extends to one end face (52; 54, 56) of the sliding bearing (50) located on the thrust bearing (70) side, and the lubricating oil discharged from the oil drain groove (230; 230A~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] Reciprocating compressors (3) for high-temperature heat pump devices (1) according to at least some embodiments, Crank axle (40) and, A sliding bearing (50) having any of the configurations [1] to [5] above, which rotatably supports the crankshaft (40), It is equipped with.

[0073] As mentioned above in [1], in the sliding bearing (50) of the reciprocating compressor (3), a permissible temperature range that can maintain the reliability of the sliding bearing (50) may be set, taking into account the temperature rise of the oil film due to frictional heat associated with the rotation of the crankshaft (40). In order to more reliably keep the oil film temperature within the permissible temperature range of the sliding bearing (50), it is conceivable to lower the oil supply temperature from the outside of the sliding bearing (50). However, in the reciprocating compressor (3) for the high-temperature heat pump system (1), if the oil supply temperature from the outside of the sliding bearing (50) is lowered too much, there is a risk of condensation of the refrigerant circulating in the refrigeration cycle (2) of the high-temperature heat pump system (1) and 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 are limits to how much the oil supply temperature can be lowered in the reciprocating compressor (3) for the high-temperature heat pump system (1). In this regard, according to the configuration described in [7] above, an oil drain groove (230; 230A~230D) is provided that communicates with the circumferential groove (210) at a circumferential position (θ) different from the oil inlet (220) and extends to at least one of the end faces (52; 54, 56) of the sliding bearing (50). This makes it possible to lengthen the main discharge path of lubricating oil from the oil inlet (220) to the oil drain groove (230; 230A~230D) in the sliding bearing (50). As a result, the low-temperature lubricating oil supplied from the oil inlet (220) is more easily drawn into the bearing gap (BC) before being discharged from the sliding bearing (50) via the oil drain groove (230; 230A~230D). Therefore, it becomes possible to increase the amount of low-temperature lubricating oil supplied to the bearing gap (BC), and the temperature rise of the oil film can be suppressed without excessively lowering the lubricating oil supply temperature.

[0074] Although several embodiments of the present invention have been described above, it goes without saying that modifications to the above embodiments are permitted as long as they do not deviate from the spirit of the present invention.

[0075] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. Furthermore, in this specification, expressions describing shapes such as quadrilaterals and cylindrical shapes shall not only represent geometrically precise quadrilaterals and cylindrical shapes, but also shapes that include uneven surfaces, chamfered surfaces, etc., to the extent that the same effect can be achieved. Furthermore, in this specification, the expressions “equipment,” “includes,” or “possess” of a component are not exclusive expressions that exclude the existence of other components. [Explanation of symbols]

[0076] 1: High-temperature heat pump device 3: Reciprocating compressor 40: Crankshaft 42: Outer surface 50: Plain bearing 52: End face 54: 1st end surface 56: 2nd end face 70: Thrust bearing 200: Bearing surface 210: Circumferential groove 220: Fuel filler cap 230(230A~230D): Oil drain groove 250 (250A~250D): Oil pocket 252: one end 254: Other end BC: Gap (bearing clearance) O: Central axis X1: Axial direction X3: Circumferential direction X4: Vertical direction θ: Circumferential position

Claims

1. A sliding bearing for a reciprocating compressor, The first end face in the axial direction, A second end face located on the opposite side in the axial direction from the first end face, A bearing surface formed between the first end face and the second end face, facing the outer circumferential surface of the crankshaft with a gap between it and the crankshaft of the reciprocating compressor, Equipped with, The aforementioned surface is A circumferential groove is provided along the circumferential direction of the bearing surface, An oil inlet opening in the circumferential groove, At least one drain groove that communicates with the circumferential groove at a circumferential position different from the oil filler port and extends to at least one of the first end face or the second end face, including Plain bearing for a reciprocating compressor.

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

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

4. The at least one drain groove includes a plurality of drain grooves provided at different circumferential positions on the bearing surface, each extending to at least one of the first or second end face. A sliding bearing for a reciprocating compressor according to claim 1 or 2.

5. The bearing surface includes at least one oil pocket provided in the axial range between each of the at least one oil drain groove and the circumferential groove, Each of the at least one oil drain grooves communicates with one axial end of the at least one oil pocket, The circumferential groove communicates with the other axial end of the at least one oil pocket at a circumferential position different from the oil filler port. A sliding bearing for a reciprocating compressor according to claim 1 or 2.

6. Crank axle and, A thrust bearing that supports the crankshaft in the axial direction, A sliding bearing according to claim 1 or 2, which rotatably supports the crankshaft and is provided adjacent to the thrust bearing in the axial direction, Equipped with, The at least one oil drain groove extends to the first end face or the second end face located on the thrust bearing side. Reciprocating compressor.

7. Crank axle and, A sliding bearing according to claim 1 or 2 that rotatably supports the crankshaft, Equipped with Reciprocating compressor for high-temperature heat pump systems.

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