Reciprocating compressor

Abstract

A reciprocating compressor is disclosed. The reciprocating compressor comprises a shell, a driving motor, a driving shaft, a piston, a cylinder block and a thrust bearing, wherein the cylinder block has a bearing loading surface on which the thrust bearing is loaded, and can have at least one oil discharge passage formed at one side of the bearing loading surface so as to allow communication with an inner space of the shell. Therefore, some of the oil supplied to the thrust bearing remains and the rest of the oil is discharged from the thrust bearing so that an input increase and frictional loss in the thrust bearing during a high-speed operation can be suppressed.

Description

reciprocating compressor

[0001] The present invention relates to a reciprocating compressor.

[0002] Compressors can be categorized into several types, including rotary compressors, scroll compressors, and reciprocating compressors, depending on the compression method and type of refrigerant used. Reciprocating compressors compress refrigerant through the reciprocating motion of a piston in a cylinder.

[0003] Reciprocating compressors can be categorized into vibrating and coupled types, depending on the piston actuation method. In an oscillating reciprocating compressor, the piston is connected to the actuator of a reciprocating motor and vibrates, reciprocating within a cylinder to compress the refrigerant. In a coupled reciprocating compressor, the piston is connected to the shaft of a rotary motor and reciprocates within a cylinder to compress the refrigerant.

[0004] In a vibrating reciprocating compressor, the suction side and the discharge side may be arranged on one side of the piston or on both sides, but in the case of a coupled reciprocating compressor, the suction side and the discharge side are mostly arranged on one side of the piston. The present invention relates to a coupled reciprocating compressor, and a reciprocating compressor may be defined as a coupled reciprocating compressor hereinafter.

[0005] In a reciprocating compressor, the axial portion of the drive shaft is inserted into the cylinder block to support it radially, and at the same time, an eccentric mass portion is placed on the cylinder block to support it axially. Accordingly, a journal bearing surface and a thrust bearing surface are formed between the drive shaft and the cylinder block. Minimizing frictional loss at the journal bearing surface and the thrust bearing surface is an important factor in improving the energy efficiency of the compressor.

[0006] Considering this, conventional drive shafts are equipped with oil channels to ensure that oil pumped from an oil feeder is evenly supplied to each bearing surface through the oil channels. However, conventional reciprocating compressors are known to install separate thrust bearings, such as ball bearings, as the thrust surfaces are in surface contact.

[0007] However, in the conventional reciprocating compressor as described above, if excessive oil is supplied to the thrust bearing, compressor performance may deteriorate as input increases during high-speed operation, and conversely, if too little oil is supplied to the thrust bearing, friction loss may increase during high-speed operation, which may lower compressor efficiency.

[0008] The purpose of the present invention is to provide a reciprocating compressor capable of suppressing input increase and friction loss in a thrust bearing during high-speed operation.

[0009] Another object of the present invention is to provide a reciprocating compressor in which an appropriate amount of oil is supplied to and maintained by a thrust bearing.

[0010] Another object of the present invention is to provide a reciprocating compressor in which some of the oil supplied to the thrust bearing remains and the remainder is drained from the thrust bearing.

[0011] Another object of the present invention is to provide a reciprocating compressor that can quickly drain oil supplied to a thrust bearing and can easily manufacture a drainage passage for this purpose.

[0012] Another object of the present invention is to provide a reciprocating compressor that stably supports a thrust bearing while simultaneously supplying and maintaining an appropriate amount of oil to the thrust bearing.

[0013] In order to achieve the object of the present invention, a reciprocating compressor including a shell, a drive motor, a drive shaft, a piston, a cylinder block, and a thrust bearing can be provided. Oil is stored in the internal space of the shell, the drive motor is provided in the internal space of the shell, the drive shaft is coupled to a rotor of the drive motor, the piston is coupled to the drive shaft and reciprocates, the cylinder block has a cylinder into which the piston is reciprocally inserted to form a compression chamber together with the piston, and the thrust bearing is provided between the drive shaft and the cylinder block to support the drive shaft in the axial direction. A bearing mounting surface on which the thrust bearing is mounted can be formed in the cylinder block, and at least one oil drainage passage can be formed on one side of the bearing mounting surface so as to be in communication with the internal space of the shell. Through this, some of the oil supplied to the thrust bearing remains and the rest is drained from the thrust bearing, thereby suppressing input increase and friction loss in the thrust bearing during high-speed operation.

[0014] For example, the oil drainage passage may be formed so that its lowest point is higher than or equal to the bearing seating surface and lower than or equal to the upper end of the thrust bearing. This allows an appropriate amount of oil to be supplied to and maintained in the thrust bearing.

[0015] For example, an oil reservoir having a preset height may extend axially on the outer periphery of the bearing seating surface. The oil drainage passage may be formed to communicate from the upper end of the oil reservoir toward the inner space of the shell. This allows the oil supplied to the thrust bearing to be maintained at an appropriate amount, thereby suppressing frictional loss in the thrust bearing.

[0016] In addition, the oil drainage passage may be formed to communicate with the internal space of the shell at a mid-height of the thrust bearing. This allows an appropriate amount of oil to be supplied to the thrust bearing, thereby suppressing an increase in input due to oil.

[0017] As another example, the thrust bearing may include a ball bearing, an upper washer, and a lower washer. The upper washer may be provided between the ball bearing and the drive shaft to support the upper side of the ball bearing, and the lower washer may be provided between the ball bearing and the cylinder block to support the lower side of the ball bearing. The oil drainage passage may be formed such that its lowest point is higher than or equal to the upper surface of the lower washer in contact with the ball bearing and lower than or equal to the middle of the ball bearing. Through this, oil shortage between the ball bearing and the lower washer can be prevented in advance, thereby suppressing friction loss, and at the same time, oil excess between the ball bearing and the lower washer can be prevented in advance, thereby suppressing an increase in input due to oil.

[0018] For example, the radial width of the bearing seating surface may be formed to be larger than the radial width of the lower washer. Through this, a stable contact area for the lower washer on the bearing seating surface can be secured, thereby suppressing the lower washer from spinning.

[0019] As another example, the drainage passage may be formed to penetrate or be sunken into the cylinder block. In this way, when the drainage passage is formed to penetrate, the strength of the cylinder block having the drainage passage is secured, whereas when the drainage passage is formed to be sunken, the drainage passage can be formed together with the casting of the cylinder block, making it easy to form the drainage passage.

[0020] For example, an oil reservoir having a preset height may extend axially on the outer circumference of the bearing seating surface. The drainage passage may be formed to slope from the upper end of the oil reservoir toward the inner surface of the shell. This allows the length of the drainage passage to be shortened, while the outlet of the drainage passage is positioned lower than the inlet, so that a portion of the oil flowing into the bearing receiving groove can be quickly drained.

[0021] In addition, an oil reservoir having a preset height may be extended axially on the outer circumference of the bearing seating surface. The oil drainage passage may be formed radially from the upper end of the oil reservoir toward the inner surface of the shell. This not only facilitates the processing of the oil drainage passage, but also allows a certain amount of oil to remain in the oil drainage passage, thereby preventing frictional loss in the thrust bearing that may occur during initial startup.

[0022] In addition, an oil reservoir having a preset height may be axially extended on the outer periphery of the bearing seating surface. The oil drainage passage may be formed axially from the upper end of the oil reservoir toward the bottom of the shell. This not only makes it easier to process the oil drainage passage, but also minimizes oil viscosity while minimizing the oil drainage passage, thereby allowing oil to be drained more quickly from the bearing receiving groove.

[0023] As another example, the cylinder block may have a bearing receiving groove formed to be sunken in, where the thrust bearing is received. The oil drainage passage may be formed on the inner surface of the bearing receiving groove at a predetermined height from the bottom surface of the bearing receiving groove. Through this, an oil storage space having an appropriate volume is formed inside the bearing receiving groove, thereby suppressing friction loss in the thrust bearing and simultaneously improving compressor performance.

[0024] For example, a shaft hole through which the drive shaft passes may be formed at the center of the bearing receiving groove, and a bearing projection extending axially along the shaft hole may be formed on the inner circumference of the bearing receiving groove to be lower than the depth of the bearing receiving groove. The bearing seating surface may be formed at the same height in the radial direction from the lower end of the outer circumference of the bearing projection. Through this, an oil storage space is formed around the thrust bearing in the cylinder block, so that an appropriate amount of oil is stably supplied, and at the same time, a contact area for the thrust bearing is secured as wide as possible to stably support the axial direction of the drive shaft.

[0025] A reciprocating compressor according to the present embodiment comprises a shell, a drive motor, a drive shaft, a piston, a cylinder block, and a thrust bearing, wherein the cylinder block has a bearing mounting surface formed on which the thrust bearing is mounted, and at least one drainage passage may be formed on one side of the bearing mounting surface so as to communicate with the internal space of the shell. Through this, some of the oil supplied to the thrust bearing remains and the remainder is drained from the thrust bearing, thereby suppressing an increase in input and friction loss in the thrust bearing during high-speed operation.

[0026] In the reciprocating compressor according to the present embodiment, the oil drainage passage may be formed to be higher than or equal to the bearing seating surface and lower than or equal to the upper end of the thrust bearing. Through this, an appropriate amount of oil can be supplied to and maintained in the thrust bearing.

[0027] A reciprocating compressor according to the present embodiment comprises a thrust bearing comprising a ball bearing, an upper washer, and a lower washer, wherein an oil drainage passage is formed to be higher than or equal to the upper surface of the lower washer in contact with the ball bearing, and lower than or equal to the middle of the ball bearing. This prevents oil shortage between the ball bearing and the lower washer in advance, thereby suppressing friction loss, and at the same time, prevents oil excess between the ball bearing and the lower washer in advance, thereby suppressing input increase due to oil.

[0028] In the reciprocating compressor according to the present embodiment, the oil drainage passage can be formed on the inner surface of the bearing receiving groove at a predetermined height from the bottom surface of the bearing receiving groove. This allows an oil storage space having an appropriate volume to be formed inside the bearing receiving groove, thereby suppressing frictional loss in the thrust bearing and simultaneously improving compressor performance.

[0029] Fig. 1 is a cross-sectional view showing the inside of a reciprocating compressor according to the present embodiment.

[0030] Fig. 2 is a perspective view showing the drive shaft and thrust bearing separated from the reciprocating compressor according to the present embodiment.

[0031] Figure 3 is a perspective view showing the drive shaft and thrust bearing separated from Figure 2.

[0032] Figure 4 is a cross-sectional view taken along the line “Ⅳ-Ⅳ” of Figure 3.

[0033] Fig. 5 is a graph comparing the amount of wear of the lower washer according to the location of the drainage passage according to the present embodiment.

[0034] Fig. 6 is a graph comparing compressor performance according to the location of the oil drainage passage according to the present embodiment.

[0035] Fig. 7 is a cross-sectional view showing another embodiment of a drainage channel.

[0036] Fig. 8 is a cross-sectional view showing another embodiment of a drainage channel.

[0037] Fig. 9 is a perspective view showing another embodiment of a drainage channel.

[0038] Figure 10 is a cross-sectional view taken along the line “Ⅹ-Ⅹ” of Figure 9.

[0039] Hereinafter, a reciprocating compressor according to the present invention will be described in detail based on an embodiment illustrated in the attached drawings. As previously described, the reciprocating compressor is provided with a thrust bearing between the drive shaft and the cylinder block. The following description focuses on an example in which the thrust bearing is provided as a ball bearing. However, the present invention is not limited thereto, and can be equally applied to a reciprocating compressor provided with a rolling contact thrust bearing, such as a roller and / or needle thrust bearing.

[0040] In addition, in the following description, the side toward the compression chamber centered on the piston is defined as the front, and the opposite side as the rear. In connection with this, the muffler assembly is described by defining the side facing the shell as the front, and the side facing away from the shell as the rear.

[0041] Fig. 1 is a cross-sectional view showing the inside of a reciprocating compressor according to the present embodiment.

[0042] Referring to FIG. 1, a reciprocating compressor according to the present embodiment may include a shell (110) forming an exterior, an electric motor (120) provided in an internal space (110a) of the shell (110) and providing driving force, a compression unit (130) receiving driving force from the electric motor (120) to compress refrigerant, an intake / discharge unit (140) guiding refrigerant to a compression chamber (130a) and discharging the compressed refrigerant, a damping unit (150) for buffering impact generated when a collision occurs between the shell (110) and the compressor body (C), and a thrust bearing (160) for axially supporting a driving shaft (125).

[0043] The shell (110) may include a lower shell (111) and an upper shell (112). The lower shell (111) and the upper shell (112) may be combined to form a sealed internal space (110a). The internal space (110a) of the shell (110) may accommodate a power unit (120) and a compression unit (130). The shell (110) may be made of a lightweight aluminum alloy (hereinafter, abbreviated as aluminum) having a high thermal conductivity.

[0044] The lower shell (111) can be formed in a roughly hemispherical shape. The bottom surface of the lower shell (111) is formed relatively flat so that the lower end of the support spring (123) described later is fixed, and an appropriate amount of oil can be stored inside the lower shell (111).

[0045] The upper shell (112) can be formed in a roughly hemispherical shape like the lower shell (111). The upper shell (112) can be joined to the lower shell (111) on the upper side of the lower shell (111) to form the internal space (110a) of the shell (110) described above.

[0046] Referring to Fig. 1, the electric motor (or driving motor) (120) according to the present embodiment may include a stator (121) and a rotor (122). The stator (121) may be elastically supported against the inner space (110a) of the shell (110), i.e., the bottom surface of the lower shell (111), and the rotor (122) may be rotatably installed inside the stator (121).

[0047] The stator (121) may include a stator core (1211) and a stator coil (1212).

[0048] The stator core (1211) is made of a metal material such as electrical steel, and when voltage is applied from the outside to the electric part (120), it performs electromagnetic interaction through electromagnetic force together with the stator coil (1212) and rotor (122) described later.

[0049] The stator core (1211) is formed in a roughly rectangular shape. For example, the inner circumference of the stator core (1211) may be formed in a circular shape, and the outer circumference may be formed in a rectangular shape. The stator core (1211) may be fixed to the lower surface of a cylinder block (131), which will be described later, by a stator fastening bolt (not shown).

[0050] The stator core (1211) can be flexibly supported by a support spring (123) at the lower end of the stator core (1211) relative to the bottom surface of the shell (110) while being spaced apart axially and radially from the inner surface of the shell (110). Accordingly, vibrations generated during operation can be suppressed from being directly transmitted to the shell (110).

[0051] The stator coil (1212) may be wound inside the stator core (1211). As described above, when voltage is applied from the outside, the stator coil (1212) generates an electromagnetic force and performs an electromagnetic interaction with the stator core (1211) and the rotor (122). Through this, the electric motor (120) generates a driving force for the reciprocating motion of the compression unit (130).

[0052] The rotor (122) may include a rotor core (1221) and a magnet (1222).

[0053] The rotor core (1221), like the stator core (1211), is made of a metal material such as electrical steel and can be formed into a roughly cylindrical shape. A drive shaft (125), which will be described later, can be press-fitted and joined to the center of the rotor core (1221).

[0054] The magnet (1222) is made of a permanent magnet and can be inserted and coupled at equal intervals along the circumference of the rotor core (1221). Accordingly, when voltage is applied, the rotor (122) rotates through electromagnetic interaction with the stator core (1211) and the stator coil (1212).

[0055] The driving shaft (125) may include a shaft portion (125a), an eccentric mass portion (125b), and an eccentric pin portion (125c). The shaft portion (125a) is a portion that is inserted into the shaft hole (1313a) of the cylinder block (131) described later and supported radially, the eccentric mass portion (125b) is a portion that extends eccentrically from the shaft portion (125a) in the radial direction, and the eccentric pin portion (125c) is a portion to which the connecting rod (126) is rotatably coupled. Accordingly, when the driving shaft (125) rotates together with the rotor (122), the rotational force is transmitted to the connecting rod (126) through the shaft portion (125a) and the eccentric pin portion (125c), so that the connecting rod (126) reciprocates together with the piston (132).

[0056] Referring to FIG. 1, the compression unit (130) according to the present embodiment may include a cylinder block (131) and a piston (132). The cylinder block (131) is elastically supported on a shell (110), and the piston (132) is coupled to a drive shaft (125) by a connecting rod (126) and moves relative to the cylinder block (131).

[0057] The cylinder block (131) may be provided on one axial side of the electric motor (120), for example, on the upper side. The cylinder block (131) is fastened to the stator (121) with a stator fastening bolt (not shown), and may be elastically supported on the lower shell (111) together with the stator (121) of the electric motor (120).

[0058] The cylinder block (131) according to the present embodiment may include a frame portion (1311), a fixed projection portion (1312) coupled to a stator (121) of a power unit (120), a shaft portion (1313) supporting a drive shaft (125), a bearing receiving groove portion (1314) provided around the shaft portion (1313) to receive a thrust bearing (160) to be described later, and a cylinder portion (cylinder) (1315) forming a compression chamber (130a).

[0059] The frame portion (1311) may be formed in a flat shape extending in the transverse direction, or may be formed in a radial shape by having a portion of the edge except for the corners processed to be thin.

[0060] The fixed protrusion (1312) may be formed at the edge of the frame portion (1311). For example, the fixed protrusion (1312) may be formed to protrude downward from the edge of the frame portion (1311) toward the power unit (120).

[0061] The shaft member (1313) can be formed to extend axially on both sides from the central portion of the frame member (1311). An shaft hole (1313a) is formed to penetrate the shaft member (1313) in the axial direction so that the drive shaft (125) can pass through it, and a bushing bearing (not shown) can be inserted and coupled to the inner circumferential surface of the shaft hole (1313a).

[0062] In this case, a bearing projection (1313b) may be formed at the top of the shaft portion (1313). In other words, the shaft hole (1313a) described above may be formed at the center of the bearing receiving groove (1314) described later, and a bearing projection (1313b) may be formed that extends annularly along the main surface of the shaft hole (1313a) and protrudes in the axial direction. Accordingly, the bearing projection (1313b) may be understood as a part of the shaft portion (1313).

[0063] The height of the bearing projection (1313b) may be formed lower than the upper surface of the frame portion (1311) described above, but the radius of the bearing receiving groove portion (1314) may be formed larger than the rotation radius of the eccentric mass portion (125b). Accordingly, the eccentric mass portion (125b) may be inserted into the inside of the bearing receiving groove portion (1314), so that the height of the bearing projection portion (1313b) may be formed lower than the upper surface of the frame portion (1311), while interference between the frame portion (1311) and the eccentric mass portion (125b) may be prevented.

[0064] In addition, the height of the bearing projection (1313b) may be formed lower than the eccentric mass portion (125b) of the driving shaft (125), for example, lower than the lower surface of the eccentric mass portion (125b). Accordingly, oil sucked through the oil passage (1251) of the driving shaft (125) may flow into the interior of the bearing receiving groove portion (1314) beyond the bearing projection (1313b).

[0065] The bearing receiving groove (1314) may be formed to be recessed by a preset depth from the upper surface of the frame portion (1311). In other words, the bearing receiving groove (1314) may be formed to be recessed by a preset depth from the center of the upper surface of the frame portion (1311), and may be formed to extend from the lower end of the outer surface of the bearing projection (1313b). Accordingly, the outer surface of the bearing projection (1313b) forms the inner surface (not shown) of the bearing receiving groove (1314), and the inner wall surface of the bearing receiving groove (1314) forms the outer surface (not shown) of the bearing receiving groove (1314).

[0066] In this case, as shown in Fig. 1, the bottom surface connecting the inner and outer circumferences of the bearing receiving groove (1314) forms a bearing seating surface (1314a) on which a thrust bearing (160) to be described later is seated, and the bearing seating surface (1314a) may be formed flat. For example, the bearing seating surface (1314a) may be formed at the same height from the lower end of the outer circumference to the inner side of the bearing protrusion (1313b), and the radial width (D1) of the bearing seating surface (1314a) may be formed to be larger than the radial width (D2) of the thrust bearing (160) and / or the lower washer (163) supporting the thrust bearing (160). Accordingly, the contact area between the thrust bearing (160) and / or the lower washer (163) supporting the thrust bearing (160) described later on the bearing seating surface (1314a) can be stably secured. As a result, the oil viscosity increases between the bearing seating surface (1314a) and the thrust bearing (160) and / or the lower washer (163) supporting the thrust bearing (160) facing it, thereby suppressing the thrust bearing (160) and / or the lower washer (163) supporting the thrust bearing (160) from slipping with respect to the bearing seating surface (1314a) during high-speed operation, thereby reducing friction loss. The bearing seating surface (1314a) will be described again later together with the oil drainage passage (170).

[0067] An oil drainage passage (170), which will be described later, may be formed on the inner wall surface of the bearing receiving groove (1314), that is, on the outer circumferential surface of the bearing receiving groove (1314). Accordingly, oil sucked through the oil passage (1251) of the drive shaft (125) flows into the interior of the bearing receiving groove (1314) beyond the bearing projection (1313b) as described above, but some of this oil may be recovered into the inner space of the shell through the oil drainage passage (170). Through this, an appropriate amount of oil is maintained inside the bearing receiving groove (1314), so as to smoothly lubricate the thrust bearing (160) while minimizing the input increase caused by the oil. The oil drainage passage (170) will be described again later together with the thrust bearing (160).

[0068] A cylinder portion (hereinafter, abbreviated as cylinder) (1315) may be formed radially eccentrically from one edge of a frame portion (1311). A piston (132) connected to a connecting rod (126) may be inserted into the inner opening of the cylinder (1315) through the radial direction, and a valve assembly (141) forming an intake / exhaust portion (140) to be described later may be mounted on the outer opening.

[0069] The piston (132) may be formed flat with an open side (rear side) facing the connecting rod (126), while the opposite side (front side) facing away from the connecting rod (126) is closed. Accordingly, the connecting rod (126) is inserted into the rear side of the piston (132) and rotatably coupled, and the front side of the piston (132) forms a compression chamber (130a) inside the cylinder (1315) together with the valve assembly (141) described later.

[0070] Referring to FIG. 1, the suction / discharge unit (140) according to the present embodiment may include a valve assembly (141), a muffler assembly (142), and a clamping member (143).

[0071] The valve assembly (141) may include an intake valve portion (not shown) and a discharge valve portion (not shown). The intake valve portion may connect the compression chamber (130a) to an intake connection groove (not shown) of a connecting muffler (not shown) to be described later, and the discharge valve portion may connect the compression chamber (130a) to an exhaust connection groove (not shown) of a connecting muffler (not shown) to be described later. Accordingly, the intake valve portion and the discharge valve portion may be formed to be adjacent to each other on a plane.

[0072] The muffler assembly (142) may include an intake muffler (142a) and a discharge muffler (142b). In other words, the muffler assembly (142) may be formed by combining an upper muffler and a lower muffler to form an intake space (S1) of the intake muffler (142a) and an discharge space (S2) of the discharge muffler (142b), respectively.

[0073] The clamping member (143) is provided at the front of the suction / discharge portion (140), that is, at the front surface of the muffler assembly (142), so as to fix the muffler assembly (142) to the cylinder block (131) of the compression portion (130).

[0074] The damping unit (150) is provided on the upper side of the compression unit (130) and the suction / discharge unit (140). The damping unit (150) may include a front damper (151) and a rear damper (152) which are respectively provided on both sides of the reciprocating direction of the piston (132), and the front damper (151) and the rear damper (152) may be made of an elastic material such as rubber. The front damper (151) can effectively suppress or buffer the impact caused by the collision between the compression unit (130) and the suction / discharge unit (140) and the shell (110) when the compressor is driven. The rear damper (152) can effectively suppress or buffer the impact caused by the collision between the shell (110) and the compression unit (130) when the compressor is driven.

[0075] In the drawing, the unexplained symbol 126 is an oil feeder, and 127 is a balance weight.

[0076] The reciprocating compressor according to the above embodiment operates as follows.

[0077] That is, when power is applied to the electric motor (120), the rotor (122) rotates. When the rotor (122) rotates, the drive shaft (125) coupled to the rotor (122) rotates and transmits the rotational force to the piston (132) through the connecting rod (126). The piston (132) reciprocates in the forward and backward direction with respect to the cylinder (1315) by the connecting rod (126).

[0078] For example, when the piston (132) moves backward (suction stroke) in the cylinder (1315), the volume of the compression chamber (130a) increases. When the volume of the compression chamber (130a) increases, the refrigerant filled in the suction space (S1) of the muffler assembly (142) through the suction pipe (115) passes through the suction valve section of the valve assembly (141) and is sucked into the compression chamber (130a).

[0079] Conversely, when the piston (132) moves forward (discharge stroke) in the cylinder (1315), the volume of the compression chamber (130a) is reduced. When the volume of the compression chamber (130a) is reduced, the refrigerant filled in the compression chamber (130a) is compressed and discharged through the discharge valve part of the valve assembly (141) into the discharge connection groove of the connecting muffler, and the refrigerant is discharged into the discharge space (S2) forming the discharge muffler (142b) and then discharged to the refrigeration cycle through the discharge pipe (not shown), repeating a series of processes.

[0080] At the same time, the oil stored in the internal space (110a) of the shell (110) is sucked up along the oil passage (1251) of the drive shaft (125), and some of this oil is supplied to each bearing surface (not shown), while some of it is sprayed from the top of the drive shaft (125) to cool the power unit (120).

[0081] At this time, a portion of the oil supplied to the bearing surface (not shown) flows into the interior of the bearing receiving groove (1314) beyond the bearing projection (1313b) described above, and this oil lubricates the thrust bearing (160) accommodated in the bearing receiving groove (1314), that is, the ball bearing (161) and the upper washer (162) and / or lower washer (163) supporting the ball bearing (161).

[0082] However, if the bearing receiving groove (1314) is formed too deeply, the ball bearing (161) becomes excessively immersed in oil, which increases the input to the drive shaft (125) including the ball bearing (161). In other words, the drive shaft (125) including the ball bearing (161) must rotate while overcoming the viscosity of the oil stored in the bearing receiving groove (1314), which increases the input and may deteriorate the compressor performance.

[0083] On the other hand, if the bearing receiving groove (1314) is formed too low, the ball (1611) of the ball bearing (161) may not rotate smoothly due to the lack of oil, which may increase friction loss between the upper washer (162) and / or the lower washer (163). In addition, in this case, the frame portion (1311) and / or the shaft portion (1313) of the cylinder block (131) may become too low, or the gap with the eccentric mass portion (125b) and / or the eccentric pin portion (125c) may widen, thereby reducing the support force for the drive shaft (125).

[0084] Accordingly, in this embodiment, an oil drainage passage (170) is formed in the bearing receiving groove (1314) so ​​that an appropriate amount of oil is always maintained in the bearing receiving groove (1314). This makes it possible to suppress an increase in input due to excess oil while simultaneously suppressing friction loss due to insufficient oil.

[0085] FIG. 2 is a perspective view showing the drive shaft and thrust bearing separated from the reciprocating compressor according to the present embodiment, FIG. 3 is a perspective view showing the drive shaft and thrust bearing separated from FIG. 2, and FIG. 4 is a cross-sectional view taken along line “Ⅳ-Ⅳ” of FIG. 3.

[0086] Referring to FIGS. 2 to 4, the cylinder block (131) according to the present embodiment may include a frame portion (1311), a fixed projection portion (1312), a bearing receiving portion (1313), a bearing receiving groove portion (1314), and a cylinder portion (1315) as described above. The frame portion (1311) may be formed in a flat plate shape or a radial plate shape, the fixed projection portion (1312) may extend from the frame portion (1311) toward the transmission portion (120), the bearing receiving portion (1313) may extend axially from the central portion of the frame portion (1311), the bearing receiving groove portion (1314) may be formed to be recessed in the upper surface of the frame portion (1311), and the cylinder portion (1315) may be formed radially on one side of the frame portion (1311). The basic configuration and corresponding operational effects of these frame parts (1311), fixed protrusion parts (1312), axle parts (1313), bearing receiving groove parts (1314) and cylinder parts (1315) are as described above.

[0087] However, an oil drainage passage (170) may be formed on the outer circumferential surface forming the inner wall surface of the bearing receiving groove (1314) to connect the interior of the bearing receiving groove (1314) and the inner space (110a) of the shell (110). The oil drainage passage (170) may be formed by penetrating the frame portion (1311) or may be formed by being sunken. This embodiment illustrates an example in which the oil drainage passage (170) is formed by penetrating the frame portion (1311).

[0088] For example, in the drainage passage (170) according to the present embodiment, the first end (171) forming the inlet of the drainage passage (170) may penetrate the outer circumferential surface forming the inner wall surface of the bearing receiving groove portion (1314), and the second end (172) forming the outlet of the drainage passage (170) may penetrate the lower surface of the frame portion (1311) toward the inner surface of the shell (110). Accordingly, the drainage passage (170) may be formed to be inclined downward at a preset angle with respect to the axial direction of the drive shaft (125) from the first end (171) to the second end (172). Through this, the length of the drainage passage (170) is shortened, and the outlet of the drainage passage (170) is positioned lower than the inlet, so that a portion of the oil flowing into the bearing receiving groove portion (1314) can be quickly drained from the bearing receiving groove portion (1314). In addition, as the length of the fuel passage (170) is shortened, the strength reduction of the cylinder block (131) due to the fuel passage (170) can be suppressed.

[0089] In addition, the fuel drainage passage (170) according to the present embodiment can be formed in a hollow shape with both ends having the same size, that is, both ends of the fuel drainage passage (170) having the same inner diameter. Accordingly, the fuel drainage passage (170) can be easily processed, thereby reducing the manufacturing cost for the cylinder block (131).

[0090] Although not shown in the drawing, the drainage passage (170) may be formed so that the inner diameters of its two ends are different. For example, the drainage passage (170) may be formed in multiple stages, and the inner diameter of the second stage (172), which forms the outlet, may be formed larger than the inner diameter of the first stage (171), which forms the inlet. Accordingly, the oil contained in the bearing receiving groove (1314) may be drained more quickly.

[0091] In addition, the oil drainage passage (170) according to the present embodiment may be formed at a position spaced apart by a preset height from the bearing seating surface (1314a) forming the bottom surface of the bearing receiving groove (1314). In other words, the bearing seating surface (1314a) may be formed flat, and the first end (171) of the oil drainage passage (170) may be formed to penetrate the frame portion (1311) toward the inner surface of the shell (110) at a position higher than the bearing seating surface (1314a). Accordingly, an oil reservoir (1314b) is formed between the bearing seating surface (1314a) and the first stage (171) of the oil drainage passage (170), so that an oil reservoir space (S3) composed of the outer surface of the bearing projection (1313b), the bearing seating surface (1314a), and the oil reservoir (1314b) can be secured inside the bearing receiving groove (1314).

[0092] Specifically, the drainage passage (170) may be formed so that the lowest point of the first stage (171) forming the entrance (hereinafter, the lowest point of the drainage passage may be understood as the lowest point of the first stage) is formed at a height higher than or equal to the lowest point of the thrust bearing (160). This embodiment illustrates an example in which the lowest point of the first stage (171) of the drainage passage (170) is formed at the same height as the lowest point of the thrust bearing (160). Accordingly, the oil amount at the bearing surface between the thrust bearing (160) and the bearing seating surface (1314a) facing it is appropriately maintained, thereby suppressing the input loss and / or friction loss described above.

[0093] For example, if the thrust bearing (160) is a ball bearing (161), an upper washer (162) and a lower washer (163) may be provided on the upper and lower sides of the ball bearing (161), respectively. In other words, an annular lower washer (163) may be mounted on the bearing mounting surface (1314a), and a ball bearing (161) may be mounted on the upper surface (163a) of the lower washer (163) so as to roll and slide.

[0094] In this case, the oil drainage passage (170) may be formed so that its lowest point is higher than or equal to the upper surface (163a) of the lower washer (163) that forms the actual lowest point of the ball bearing (161), for example, at the same height as the upper surface (163ㅁ) of the lower washer (163). Accordingly, an appropriate amount of oil is always filled between the plurality of balls (1611) forming the ball bearing (161) and the lower washer (163), so that the oil is applied to the outer surface of the balls (1611). Then, as the space between the plurality of balls (1611) and the ball cage (1612) supporting the plurality of balls (1611) is lubricated, the plurality of balls (1611) forming the ball bearing (161) rotate smoothly with respect to the ball cage (1612), thereby suppressing friction loss and / or wear between the balls (1611) of the ball bearing (161) and the lower washer (163) as well as the upper washer (162).

[0095] At the same time, it is possible to suppress excessive oil storage inside the bearing receiving groove (1314). In other words, since the lowest point of the first stage (171) of the drainage passage (170) is formed at the same height as the upper surface (163a) of the lower washer (163), oil that flows in higher (a lot) than the upper surface (163a) of the lower washer (163) is discharged into the internal space of the shell through the drainage passage (170). Then, the bearing receiving groove (1314) is always filled with an appropriate amount of oil, for example, a level slightly higher than the upper surface (163a) of the lower washer (163), thereby suppressing an increase in input due to the oil and increasing the compressor efficiency.

[0096] In addition, the drainage passage (170) may be formed so that the inner diameter of the first stage (171) is smaller than the height of the thrust bearing (160), for example, approximately half the height of the thrust bearing (160). In other words, when the thrust bearing (160) is a ball bearing (161), the highest point of the first stage (171) of the drainage passage (170) may be formed so that it is approximately at the middle of the ball (1611) (or the middle of the ball cage). Accordingly, by appropriately securing the inner diameter of the drainage passage (170), it is possible to maintain an appropriate amount of oil in the bearing receiving groove (1314).

[0097] In addition, although not illustrated in the drawing, a plurality of drainage passages (170) may be formed along the circumferential direction. In this case, the drainage passages (170) may be formed at equal intervals along the circumferential direction. Accordingly, oil from the oil storage space (S3) can be drained more quickly, while the oil level in the oil storage space (S3) can be maintained as uniformly as possible.

[0098] Fig. 5 is a graph comparing the amount of wear of the lower washer according to the location of the drainage passage according to the present embodiment, and Fig. 6 is a graph comparing the performance of the compressor according to the location of the drainage passage according to the present embodiment.

[0099] Referring to FIG. 5, it can be seen that the amount of wear (hereinafter abbreviated as wear amount) between the ball bearing (161) and the lower washer (163) is greatly changed by the height of the oil stored in the bearing receiving groove (1314) (hereinafter abbreviated as oil level height) based on the upper surface (163a) of the lower washer (163).

[0100] For example, when the height of the oil (oil level) stored inside the bearing receiving groove (1314) is higher than the upper surface (163a) of the lower washer (163), it can be seen that the amount of wear is maintained below the allowable standard. This can be seen because a sufficient amount of oil is maintained in the bearing receiving groove (1314) as the lowest point of the oil drainage passage (170) corresponding to the oil level is formed higher than the upper surface (163a) of the lower washer (163).

[0101] On the other hand, when the oil level height in the bearing receiving groove (1314) is lower than the upper surface (163a) of the lower washer (163), it can be seen that the wear amount exceeds the allowable standard. This can be seen because, as the lowest point of the drainage passage (170) corresponding to the oil level height is formed lower than the upper surface (163a) of the lower washer (163), oil shortage occurs in the bearing receiving groove (1314), and as a result, the ball (1611) of the ball bearing (161) is unable to rotate because it is engaged with the ball cage (1612), causing slippage between the ball (1611) of the ball bearing (161) and the lower washer (163).

[0102] Through this, it can be seen that it is advantageous for reducing the amount of wear to form the lowest point of the oil drainage passage (170) corresponding to the oil level height in the bearing receiving groove (1314) to be higher than or equal to the lowest point of the ball (1611) of the ball bearing (161), that is, the upper surface (163a) of the lower washer (163) with which the ball (1611) comes into contact.

[0103] Referring to Fig. 6, it can be seen that the compressor efficiency greatly changes based on the height of the oil stored in the bearing receiving groove (1314) (hereinafter, abbreviated as oil level height) relative to the upper surface (163a) of the lower washer (163) and the middle height of the ball bearing (161).

[0104] For example, when the oil level in the bearing receiving groove (1314) is lower than the upper surface (163a) of the lower washer (163), it can be seen that the compressor efficiency does not meet the performance standard. This can be seen to be because, as the lowest point of the oil drainage passage (170) corresponding to the oil level is formed lower than the middle height of the ball bearing (ball cage) (161), friction loss occurs due to oil shortage between the ball bearing (161) and the lower washer (163), as seen in the drawing ** above.

[0105] On the other hand, it can be seen that the compressor efficiency does not meet the performance standard even when the oil level height in the bearing receiving groove (1314) is higher than the middle height of the ball bearing (161). This can be seen as being because the lowest point of the oil drainage passage (170) corresponding to the oil level height is formed high, resulting in excess oil in the bearing receiving groove (1314), and as a result, the oil in the bearing receiving groove (1314) generates a kind of flow resistance, which induces an increase in input.

[0106] Through this, it can be seen that it is advantageous for increasing compressor efficiency to form the lowest point of the oil drainage passage (170) corresponding to the oil level height in the bearing receiving groove (1314) between the lowest point and the middle of the ball bearing (161), that is, between the upper surface (163a) of the lower washer (163) with which the ball (1611) comes into contact and the middle height of the ball cage (1612).

[0107] Meanwhile, there are other examples of the drainage passage as follows.

[0108] That is, in the above-described embodiment, the drainage passage is formed slanted, but in some cases, the drainage passage may be formed radially.

[0109] Figure 7 is a cross-sectional view showing another embodiment of a drainage channel.

[0110] Referring back to FIGS. 1 to 4, the basic structure and the resulting operational effects of the cylinder block (131) according to the present embodiment are almost similar to those of the above-described embodiment. For example, the cylinder block (131) according to the present embodiment has a bearing receiving groove (1314) formed sunken in the center of the upper surface of the frame portion (1311), and a bearing projection (1313b) forming an inner surface of the bearing receiving groove (1314) while forming a shaft portion (1313) is formed in an annular shape at the center of the bearing receiving groove (1314), and a bottom surface extending from the lower end of the outer surface of the bearing projection (1313b) to the outer surface of the bearing receiving groove (1314) may be formed flat as a bearing seating surface (1314a) on which a ball bearing (161) forming a thrust bearing (160) and / or a lower washer (163) are seated. In this case, at least one oil drainage passage (170) may be formed on the outer surface of the bearing receiving groove (1314) at a position spaced apart from the bearing seating surface (1314a) by a preset height, that is, at the lower end of the outer surface of the bearing receiving groove (1314), with the oil reservoir (1314b) connected to the bearing seating surface (1314a) interposed therebetween. Accordingly, an oil reservoir space (S3) may be formed on the inside of the bearing receiving groove (1314) by the outer surface of the bearing protrusion (1313b), the bearing seating surface (1314a), and the oil reservoir (1314b).

[0111] Also, in this case, the depth of the oil storage space (S3), that is, the first stage (171) forming the entrance of the oil drainage passage (170), can be formed at the same height as in the above-described embodiment. For example, the first stage (171) of the oil drainage passage (170) can be formed so that its lowest point is located at the lower end of the ball bearing (161) forming the thrust bearing (160), that is, between the upper surface (163a) of the lower washer (163) supporting the ball bearing (161) and the middle of the ball bearing (161). Accordingly, an appropriate amount of oil is maintained in the oil storage space (S3), thereby suppressing friction loss and improving compressor efficiency.

[0112] However, in the present embodiment, the drainage passage (170) may be formed in the radial direction. For example, as shown in FIG. 7, the first end (171) of the drainage passage (170) may penetrate the outer surface of the bearing receiving groove (1314), and the second end (172) of the drainage passage (170) may penetrate the outer surface of the frame portion (1311) facing the inner surface of the shell (110). In other words, the first end (171) and the second end (172) of the drainage passage (170) may be formed at the same height along the radial direction. Accordingly, the drainage passage (170) may be formed in a straight line along the radial direction of the driving shaft (125).

[0113] When the drainage passage (170) is formed in a straight line along the radial direction as described above, the drainage passage (170) can be easily processed. In other words, when the drainage passage (170) is formed in the radial direction of the drive shaft (125) as in the present embodiment, it can be processed relatively easily compared to when it is formed at an angle with respect to the axial direction of the drive shaft (125) as in the above-described embodiment.

[0114] In addition, in the case where the drainage passage (170) is formed in the radial direction as in the present embodiment, a certain amount of oil may remain in the drainage passage (170), so that the oil remaining in the drainage passage (170) can quickly flow into the oil storage space (S3) during initial startup. This can prevent friction loss to the thrust bearing (160) that may occur during initial startup in advance.

[0115] Meanwhile, another example of a drainage channel is as follows.

[0116] That is, in the embodiments described above, the oil drainage passage is formed on the outer surface of the bearing receiving groove, but in some cases, the oil drainage passage may be formed on the bottom surface of the bearing receiving groove.

[0117] Figure 8 is a cross-sectional view showing another embodiment of a drainage channel.

[0118] Referring back to FIGS. 1 to 4, the basic structure and the resulting operational effects of the cylinder block (131) according to the present embodiment are almost similar to those of the above-described embodiment. For example, the cylinder block (131) according to the present embodiment has a bearing receiving groove (1314) formed sunken in the center of the upper surface of the frame portion (1311), and a bearing projection (1313b) forming an inner surface of the bearing receiving groove (1314) while forming a shaft portion (1313) is formed in an annular shape at the center of the bearing receiving groove (1314), and a bottom surface extending from the lower end of the outer surface of the bearing projection (1313b) to the outer surface of the bearing receiving groove (1314) may be formed flat as a bearing seating surface (1314a) on which a ball bearing (161) forming a thrust bearing (160) and / or a lower washer (163) are seated. In this case, at least one oil drainage passage (170) may be formed on the outer surface of the bearing receiving groove (1314) at a position spaced apart from the bearing seating surface (1314a) by a preset height, that is, at the lower end of the outer surface of the bearing receiving groove (1314), with the oil reservoir (1314b) connected to the bearing seating surface (1314a) interposed therebetween. Accordingly, an oil reservoir space (S3) may be formed on the inside of the bearing receiving groove (1314) by the outer surface of the bearing protrusion (1313b), the bearing seating surface (1314a), and the oil reservoir (1314b).

[0119] Also in this case, the depth of the oil storage space (S3), that is, the first stage (171) forming the entrance of the oil drainage passage (170), can be formed at the same height as in the embodiment described above. For example, the first stage (171) of the oil drainage passage (170) can be formed to be located between the lower end of the ball bearing (161) forming the thrust bearing (160), that is, the upper surface (163a) of the lower washer (163) supporting the ball bearing (161) and the middle of the ball bearing (161). Accordingly, as described above, an appropriate amount of oil is maintained in the oil storage space (S3), thereby suppressing friction loss and improving compressor efficiency.

[0120] However, in the present embodiment, the drainage passage (170) may be formed in the axial direction. For example, as shown in FIG. 8, the outer circumferential surface forming the inner wall surface of the bearing receiving groove (1314) is formed in two steps, the bearing seating surface (1314a) described above is formed at the inner end of the bearing receiving groove (1314), and the first step (171) of the drainage passage (170) may penetrate the outer end of the bearing receiving groove (1314). Between the inner and outer ends of the bearing receiving groove (1314), that is, between the bearing seating surface (1314a) and the drainage passage (170), the previously described oil level (1314b) may be formed in a step of a preset height, so that the previously described oil storage space (S3) may be formed.

[0121] In addition, the first end (171) of the drainage passage (170) may penetrate from the outside of the bearing seating surface (1314a) to the outer end of the bearing receiving groove (1314), and the second end (172) of the drainage passage (170) may penetrate to the lower surface of the frame portion (1311) facing the bottom surface of the shell (110). Accordingly, the first end (171) and the second end (172) of the drainage passage (170) may be formed on the same axis along the axial direction.

[0122] When the drainage passage (170) is formed in a straight line along the axial direction as described above, the drainage passage (170) can be processed more easily. In other words, when the drainage passage (170) is formed in the axial direction of the drive shaft (125) as in the present embodiment, it can be processed relatively easily compared to when it is formed at an angle to the axial direction of the drive shaft (125) as in the embodiment of FIG. 4, and also when it is formed in the radial direction of the drive shaft (125) as in the embodiment of FIG. 7.

[0123] In addition, in the case where the oil drainage passage (170) is formed in the axial direction as in the present embodiment, not only is the oil drainage passage (170) minimized, but oil viscosity is also minimized, so that oil can be drained more quickly from the bearing receiving groove (1314).

[0124] Meanwhile, another example of a drainage channel is as follows.

[0125] That is, in the embodiment described above, the oil drainage passage is formed penetrating the cylinder block, but in some cases, the oil drainage passage may be formed sunken into the cylinder block.

[0126] Fig. 9 is a perspective view showing another embodiment of a drainage channel, and Fig. 10 is a cross-sectional view taken along line “Ⅹ-Ⅹ” of Fig. 9.

[0127] Referring back to FIGS. 1 to 4, the basic structure and the resulting operational effects of the cylinder block (131) according to the present embodiment are almost similar to those of the above-described embodiment. For example, the cylinder block (131) according to the present embodiment has a bearing receiving groove (1314) formed sunken in the center of the upper surface of the frame portion (1311), and a bearing projection (1313b) forming an inner surface of the bearing receiving groove (1314) while forming a shaft portion (1313) is formed in an annular shape at the center of the bearing receiving groove (1314), and a bottom surface extending from the lower end of the outer surface of the bearing projection (1313b) to the outer surface of the bearing receiving groove (1314) may be formed flat as a bearing seating surface (1314a) on which a ball bearing (161) forming a thrust bearing (160) and / or a lower washer (163) are seated. In this case, at least one oil drainage passage (170) may be formed on the outer surface of the bearing receiving groove (1314) at a position spaced apart from the bearing seating surface (1314a) by a preset height, that is, at the lower end of the outer surface of the bearing receiving groove (1314), with the oil reservoir (1314b) connected to the bearing seating surface (1314a) interposed therebetween. Accordingly, an oil reservoir space (S3) may be formed on the inside of the bearing receiving groove (1314) by the outer surface of the bearing protrusion (1313b), the bearing seating surface (1314a), and the oil reservoir (1314b).

[0128] Also, in this case, the depth of the oil storage space (S3), that is, the first stage (171) forming the entrance of the oil drainage passage (170), may be formed at the same height as the embodiments of the aforementioned FIGS. 4 and 7. For example, the first stage (171) of the oil drainage passage (170) may be formed so that its lowest point is located at the lower end of the ball bearing (161) forming the thrust bearing (160), that is, between the upper surface (163a) of the lower washer (163) supporting the ball bearing (161) and the middle of the ball bearing (161). Accordingly, an appropriate amount of oil is maintained in the oil storage space (S3), thereby suppressing friction loss and improving compressor efficiency.

[0129] However, in the present embodiment, the drainage passage (170) may be formed to be recessed in the axial direction by a preset depth from the upper surface of the frame portion (1311) forming part of the cylinder block (131). For example, as shown in FIGS. 9 and 10, the first end (171) of the drainage passage (170) may be opened to the outer surface of the bearing receiving groove portion (1314), and the first end (171) of the drainage passage (170) may be opened to the outer surface of the frame portion (1311) facing the inner surface of the shell. In other words, the first end (171) and the second end (172) of the drainage passage (170) may be formed to be recessed to the same height along the radial direction. Accordingly, the drainage passage (170) may be formed in a straight line along the radial direction of the drive shaft (125) with the upper surface open.

[0130] In the case where the drainage passage (170) is formed to be sunken in the frame portion (1311) as described above, the drainage passage (170) can be formed more easily. In other words, since the drainage passage (170) is formed to be sunken in the frame portion (1311) as in the present embodiment, the drainage passage (170) can be formed together when the cylinder block (131) is cast. Accordingly, post-processing of the drainage passage (170) can be eliminated after the casting work for the cylinder block (131), thereby simplifying the manufacturing process for the cylinder block (131).

[0131] In addition, in the case where the drainage passage (170) is formed to be sunken as in the present embodiment, the upper surface of the drainage passage (170) is opened so that oil flying from the drive shaft (125) during initial operation is quickly supplied to the bearing receiving groove (1314) through the drainage passage (170), thereby reducing friction loss for the thrust bearing (160).

Claims

1. Shell in which oil is stored; A driving motor provided in the internal space of the above shell; A driving shaft coupled to the rotor of the above driving motor; A piston coupled to the above driving shaft and performing reciprocating motion; A cylinder block having a cylinder so that the piston is reciprocally inserted to form a compression chamber together with the piston; and It includes a thrust bearing provided between the above driving shaft and the cylinder block to axially support the driving shaft, A reciprocating compressor in which a bearing mounting surface on which the thrust bearing is mounted is formed in the cylinder block, and at least one oil drainage passage is formed on one side of the bearing mounting surface so as to be connected to the internal space of the shell.

2. In paragraph 1, The above-mentioned drainage passage is, A reciprocating compressor in which the lowest point is formed to be higher than or equal to the bearing seating surface and lower than or equal to the upper end of the thrust bearing.

3. In paragraph 2, On the outer circumference of the above bearing mounting surface, a low-level oil surface having a preset height is extended in the axial direction, The above-mentioned drainage passage is, A reciprocating compressor formed so as to communicate with the inner space of the shell from the upper part of the above-mentioned low-level surface.

4. In paragraph 2, The above-mentioned drainage passage is, A reciprocating compressor formed so as to communicate with the internal space of the shell at the middle height of the above thrust bearing.

5. In paragraph 1, The above thrust bearing, ball bearing; An upper washer provided between the ball bearing and the driving shaft to support the upper side of the ball bearing; and A lower washer is provided between the ball bearing and the cylinder block to support the lower side of the ball bearing, The above-mentioned drainage passage is, A reciprocating compressor in which the lowest point is formed to be higher than or equal to the upper surface of the lower washer in contact with the ball bearing and lower than or equal to the middle of the ball bearing.

6. In paragraph 5, A reciprocating compressor in which the radial width of the bearing seating surface is formed larger than the radial width of the lower washer.

7. In paragraph 1, The above-mentioned drainage passage is, A reciprocating compressor formed by penetrating or sinking into the above cylinder block.

8. In paragraph 7, On the outer circumference of the above bearing mounting surface, a low-level oil surface having a preset height is extended in the axial direction, The above-mentioned drainage passage is, A reciprocating compressor formed so as to be inclined toward the inner surface of the shell from the upper end of the above-mentioned low-level surface.

9. In paragraph 7, On the outer circumference of the above bearing mounting surface, a low-level oil surface having a preset height is extended in the axial direction, The above-mentioned drainage passage is, A reciprocating compressor formed radially toward the inner surface of the shell from the upper end of the above-mentioned low-pressure area.

10. In paragraph 7, On the outer circumference of the above bearing mounting surface, a low-level oil surface having a preset height is extended in the axial direction, The above-mentioned drainage passage is, A reciprocating compressor formed axially from the top of the above low-level surface toward the bottom of the shell.

11. In any one of paragraphs 1 to 10, In the above cylinder block, a bearing receiving groove for receiving the thrust bearing is formed sunken, The above-mentioned drainage passage is, A reciprocating compressor formed on the inner surface of the bearing receiving groove by a predetermined height from the bottom surface of the bearing receiving groove.

12. In paragraph 11, At the center of the bearing receiving groove, an axle hole is formed through which the driving shaft passes, and on the inner circumference of the bearing receiving groove, a bearing projection extending axially along the axle hole is formed lower than the depth of the bearing receiving groove. The above bearing mounting surface is, A reciprocating compressor formed at the same height along the radial direction from the lower part of the outer surface of the bearing protrusion.

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