Reciprocating compressor provided with dual oil pumps

Abstract

This reciprocating compressor comprises: a case including an oil storage tank; a motor including a stator that is installed inside the case and a rotor that rotates about the stator; a drive shaft that rotates integrally with the rotor and includes a cavity formed in a lower portion thereof; a primary oil pump that is inserted into the cavity of the drive shaft and installed in the case; a secondary oil pump, of which the lower end is inserted into the drive shaft and which is coupled to the primary oil pump; a primary oil passage that is formed between the inner circumferential surface of the cavity of the drive shaft and the primary oil pump; and a secondary oil passage that is formed, between the outer circumferential surface of the lower end of the drive shaft and the secondary oil pump, around the primary oil passage. When the drive shaft rotates, oil contained in the oil storage tank moves along the primary oil passage and the secondary oil passage to an upper portion of the cavity of the drive shaft.

Description

Reciprocating compressor with dual oil pumps

[0001] The present disclosure relates to a reciprocating compressor, and more particularly, to a reciprocating compressor having a dual oil pump.

[0002] A compressor is a mechanical device that compresses an incoming gas, increasing its pressure and discharging it. Depending on their operating principles, compressors can be divided into reciprocating compressors and rotary compressors.

[0003] Rotary compressors include rotary compressors and scroll compressors.

[0004] Among reciprocating compressors, there is a reciprocating compressor that converts the rotational motion of a motor into the linear reciprocating motion of a piston using a crank shaft and connecting rod to suck in, compress, and discharge gas.

[0005] Typically, reciprocating compressors use an oil pump that is driven by the rotation of a motor to supply oil to the internal components.

[0006] However, when the reciprocating compressor operates at low speed, the amount of oil supplied to the internal components by the oil pump may be reduced.

[0007] The above information is provided solely as background information to aid in understanding the present disclosure. No determination has been made, and no assertion has been made, as to whether any of the above is applicable as prior art in connection with the present disclosure.

[0008] One aspect of the present disclosure is to address at least the problems and / or disadvantages described above and to provide at least one advantage described below. Accordingly, one aspect of the present disclosure provides a reciprocating compressor using an external motor.

[0009] Additional aspects will be partly described in the description below, partly will be obvious from the description, or may be learned by practicing the embodiments presented.

[0010] A reciprocating compressor according to one or more embodiments of the present disclosure may include: a case including an oil reservoir; a motor including a stator installed inside the case and a rotor that rotates with respect to the stator; a drive shaft that rotates integrally with the rotor and includes a cavity formed at a lower portion; a primary oil pump that is inserted into the cavity of the drive shaft and is installed in the case; a secondary oil pump into which a lower end of the drive shaft is inserted and that is coupled with the primary oil pump; a primary oil channel formed between an inner circumferential surface of the cavity of the drive shaft and the primary oil pump; and a secondary oil channel formed between an outer circumferential surface of a lower end of the drive shaft and the secondary oil pump around the primary oil channel. When the drive shaft rotates, oil contained in the oil reservoir can move to an upper portion of the cavity of the drive shaft along the primary oil channel and the secondary oil channel.

[0011] According to one or more embodiments of the present disclosure, the drive shaft may include a first oil supply passage having a spiral shape formed on an outer surface of the upper portion. The secondary oil pump may be formed in the shape of a cylindrical container with a bottom.

[0012] According to one or more embodiments of the present disclosure, the drive shaft may include a communication hole formed adjacent to the upper end of the cavity. Oil contained in the oil reservoir may flow into the secondary oil pump through the lower portion of the secondary oil pump. A portion of the oil flowing into the secondary oil pump may move upward along the primary oil path. The remaining oil may move upward along the secondary oil path and flow into the cavity through the communication hole, and may move to the upper end of the cavity together with a portion of the oil flowing along the primary oil path.

[0013] According to one or more embodiments of the present disclosure, the secondary oil passage may be formed as a spiral groove formed on the outer surface of the lower portion of the drive shaft inserted into the secondary oil pump. The spiral direction of the spiral groove of the secondary oil passage may be the same as the spiral direction of the first oil supply passage.

[0014] According to one or more embodiments of the present disclosure, the secondary oil path may be formed as a spiral groove formed on the inner surface of the secondary oil pump. The spiral direction of the spiral groove of the secondary oil path may be opposite to the spiral direction of the first oil supply path.

[0015] According to one or more embodiments of the present disclosure, the secondary oil pump may include a plurality of oil inlets formed on at least one of a bottom and a lower portion of an outer surface adjacent to the bottom.

[0016] According to one or more embodiments of the present disclosure, the upper end of the secondary oil passage may be formed below the upper end of the secondary oil pump.

[0017] According to one or more embodiments of the present disclosure, the upper end of the secondary oil passage may be formed to correspond to the communicating hole.

[0018] According to one or more embodiments of the present disclosure, the upper end of the secondary oil pump may be adjacent to the lower surface of the rotor and may be positioned above the surface of the oil contained in the oil reservoir.

[0019] According to one or more embodiments of the present disclosure, oil contained in the oil reservoir may be introduced into the secondary oil pump through the upper portion of the secondary oil pump. The oil introduced into the secondary oil pump may move to the lower portion of the drive shaft along the secondary oil path and to the upper portion of the cavity of the drive shaft along the primary oil path.

[0020] According to one or more embodiments of the present disclosure, the secondary oil passage may be formed as a spiral groove formed on the outer circumferential surface of the lower portion of the drive shaft inserted into the secondary oil pump. The spiral direction of the spiral groove of the secondary oil passage may be opposite to the spiral direction of the first oil supply passage.

[0021] According to one or more embodiments of the present disclosure, the secondary oil path may be formed as a spiral groove formed on the inner surface of the secondary oil pump. The spiral direction of the spiral groove of the secondary oil path may be the same as the spiral direction of the first oil supply path.

[0022] According to one or more embodiments of the present disclosure, the secondary oil pump may include at least one oil inlet formed on the outer surface adjacent to the top.

[0023] According to one or more embodiments of the present disclosure, the upper end of the secondary oil passage may be formed at the upper end of the secondary oil pump.

[0024] According to one or more embodiments of the present disclosure, the upper end of the secondary oil pump may be adjacent to the lower surface of the rotor and may be positioned below the surface of the oil contained in the oil reservoir.

[0025] According to one or more embodiments of the present disclosure, a coupling hole may be formed at the bottom of the secondary oil pump to which the primary oil pump is coupled.

[0026] According to one or more embodiments of the present disclosure, the coupling hole may be formed in any one of a circular, polygonal, and oval shape.

[0027] According to one or more embodiments of the present disclosure, the primary oil pump and the secondary oil pump may be coupled by a screw connection or a press-fit connection.

[0028] According to one or more embodiments of the present disclosure, a gap between the inner surface of the secondary oil pump and the outer surface of the lower portion of the drive shaft may be 0.1 mm to 0.15 mm.

[0029] Other aspects, advantages and salient features of the present disclosure will become apparent to those skilled in the art from the following detailed description of various embodiments of the present disclosure taken in conjunction with the accompanying drawings.

[0030] The above-described and other aspects, features, and advantages of the embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings. In the accompanying drawings:

[0031] FIG. 1 is a perspective view showing a reciprocating compressor according to one or more embodiments of the present disclosure.

[0032] FIG. 2 is a cross-sectional view showing a reciprocating compressor according to one or more embodiments of the present disclosure.

[0033] Fig. 3 is a partial cross-sectional view showing an enlarged view of the main components of the reciprocating compressor of Fig. 2.

[0034] FIG. 4 is a perspective view showing a drive shaft assembly of a reciprocating compressor according to one or more embodiments of the present disclosure.

[0035] Figure 5 is an exploded perspective view of the drive shaft assembly of Figure 4.

[0036] Figure 6 is a cross-sectional view of the drive shaft assembly of Figure 4.

[0037] Fig. 7 is a perspective view showing a secondary oil pump of the drive shaft assembly of Fig. 4.

[0038] FIG. 8 is a perspective view showing a secondary oil pump of a reciprocating compressor according to one or more embodiments of the present disclosure.

[0039] FIG. 9 is a perspective view showing a secondary oil pump of a reciprocating compressor according to one or more embodiments of the present disclosure.

[0040] FIG. 10 is a perspective view showing a drive shaft assembly of a reciprocating compressor according to one or more embodiments of the present disclosure.

[0041] Figure 11 is an exploded perspective view of the drive shaft assembly of Figure 10.

[0042] Fig. 12 is a cross-sectional view of the drive shaft assembly of Fig. 10.

[0043] Fig. 13 is a perspective view showing a secondary oil pump of the drive shaft assembly of Fig. 10.

[0044] FIG. 14 is a cross-sectional perspective view showing a state in which a primary oil pump and a secondary oil pump of a reciprocating compressor according to one or more embodiments of the present disclosure are coupled to each other.

[0045] FIG. 15 is a perspective view showing a state in which a primary oil pump and a secondary oil pump of a reciprocating compressor according to one or more embodiments of the present disclosure are coupled to each other.

[0046] FIG. 16 is a perspective view showing a state in which a primary oil pump and a secondary oil pump of a reciprocating compressor according to one or more embodiments of the present disclosure are coupled to each other.

[0047] FIG. 17 is a perspective view showing a state in which a primary oil pump and a secondary oil pump of a reciprocating compressor according to one or more embodiments of the present disclosure are coupled to each other.

[0048] Fig. 18 is a perspective view showing the primary oil pump and secondary oil pump of Fig. 17 separated.

[0049] FIG. 19 is a cross-sectional view showing a reciprocating compressor according to one or more embodiments of the present disclosure.

[0050] Fig. 20 is a partial cross-sectional view showing an enlarged view of the main components of the reciprocating compressor of Fig. 19.

[0051] FIG. 21 is a perspective view showing a drive shaft assembly of a reciprocating compressor according to one or more embodiments of the present disclosure.

[0052] Figure 22 is an exploded perspective view of the drive shaft assembly of Figure 21.

[0053] Figure 23 is a cross-sectional view of the drive shaft assembly of Figure 21.

[0054] Fig. 24 is a perspective view showing a secondary oil pump of the drive shaft assembly of Fig. 21.

[0055] FIG. 25 is a perspective view showing a secondary oil pump of a reciprocating compressor according to one or more embodiments of the present disclosure.

[0056] FIG. 26 is a perspective view showing a secondary oil pump of a reciprocating compressor according to one or more embodiments of the present disclosure.

[0057] Fig. 27 is a partially enlarged cross-sectional view showing the secondary oil pump of Fig. 26 submerged in a low-pressure tank.

[0058] FIG. 28 is a perspective view showing a drive shaft assembly of a reciprocating compressor according to one or more embodiments of the present disclosure.

[0059] Figure 29 is an exploded perspective view of the drive shaft assembly of Figure 28.

[0060] Fig. 30 is a cross-sectional view of the drive shaft assembly of Fig. 28.

[0061] Fig. 31 is a perspective view showing a secondary oil pump of the drive shaft assembly of Fig. 28.

[0062] FIG. 32 is a cross-sectional perspective view showing a state in which a primary oil pump and a secondary oil pump of a reciprocating compressor according to one or more embodiments of the present disclosure are coupled to each other.

[0063] FIG. 33 is a perspective view showing a state in which a primary oil pump and a secondary oil pump of a reciprocating compressor according to one or more embodiments of the present disclosure are coupled to each other.

[0064] FIG. 34 is a drawing showing the movement of oil by rotation of a drive shaft of a reciprocating compressor according to one or more embodiments of the present disclosure.

[0065] Figure 35 is an enlarged cross-sectional view of part A of Figure 34.

[0066] FIG. 36 is a drawing showing the movement of oil by rotation of a drive shaft of a reciprocating compressor according to one or more embodiments of the present disclosure.

[0067] Figure 37 is an enlarged cross-sectional view of part B of Figure 36.

[0068] Throughout the drawings, similar reference numbers are used to describe identical or similar elements, features, and structures.

[0069] The following description, with reference to the attached drawings, is provided to facilitate a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. While it includes numerous specific details to aid understanding, these are to be considered merely exemplary. Accordingly, those skilled in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. Furthermore, descriptions of known functions and configurations may be omitted for clarity and brevity.

[0070] The terms and words used in the following description and claims are not to be construed as limited to their bibliographic meanings, but rather have been used by the inventors solely to facilitate a clear and consistent understanding of the present disclosure. Accordingly, it will be apparent to those skilled in the art that the following description of various embodiments of the present invention is provided for illustrative purposes only and is not intended to limit the present invention as defined by the appended claims and their equivalents.

[0071] Singular forms should be understood to include plural referents unless the context clearly indicates otherwise. Thus, for example, a reference to "a surface of a part" includes a reference to one or more of those surfaces.

[0072] In this document, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" may include any one of the items listed together in that phrase, or all possible combinations thereof.

[0073] The term "and / or" includes any combination of a plurality of related described elements or any one of a plurality of related described elements.

[0074] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish one component from another and do not qualify the components in any other respect (e.g., importance or order).

[0075] When a component (e.g., a first component) is referred to as being "coupled" or "connected" to another component (e.g., a second component), with or without the terms "functionally" or "communicatively," it means that the component can be connected to the other component directly (e.g., wired), wirelessly, or through a third component.

[0076] The terms "include" or "have" are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in this document, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0077] When a component is said to be “connected,” “coupled,” “supported,” or “in contact with” another component, this includes not only cases where the components are directly connected, coupled, supported, or in contact, but also cases where the components are indirectly connected, coupled, supported, or in contact through a third component.

[0078] When we say that a component is "on" another component, this includes not only cases where the component is in contact with the other component, but also cases where there is another component between the two components.

[0079] In addition, terms such as 'front end', 'rear end', 'upper end', 'lower end', 'top end', and 'bottom end' used in the present disclosure are defined based on the drawings, and the shape and position of each component are not limited by these terms.

[0080] The present disclosure relates to a hermetic reciprocating compressor (1) capable of increasing the amount of oil supplied to internal components compared to a conventional reciprocating compressor when the reciprocating compressor operates at low speed.

[0081] Hereinafter, a reciprocating compressor (1) according to one or more embodiments of the present disclosure will be described in detail with reference to the attached drawings.

[0082] FIG. 1 is a perspective view showing a reciprocating compressor (1) according to one or more embodiments of the present disclosure.

[0083] Referring to FIG. 1, a reciprocating compressor (1) according to one embodiment of the present disclosure may include a case (10).

[0084] The case (10) forms the exterior of the reciprocating compressor (1). The case (10) is formed as a sealed container. The case (10) may include a refrigerant inlet pipe (13) through which refrigerant is introduced and a refrigerant discharge pipe (14) through which refrigerant is discharged.

[0085] A reciprocating compressor (1) can form a refrigeration cycle together with a condenser, an expansion valve, and an evaporator. In this case, a refrigerant inlet pipe (13) can be connected to the evaporator, and a refrigerant discharge pipe (14) can be connected to the condenser.

[0086] The case (10) may include an upper case (11) and a lower case (12). The upper case (11) is coupled to the upper end of the lower case (12) to form the case (10).

[0087] The joint between the upper case (11) and the lower case (12) is sealed.

[0088] A refrigerant inlet pipe (13) and a refrigerant discharge pipe (14) are provided in the lower case (12). The refrigerant inlet pipe (13) and the refrigerant discharge pipe (14) are connected to a compression unit (40) (see Fig. 2) installed inside the case (10). Low-temperature / low-pressure refrigerant can be introduced into the refrigerant inlet pipe (13). High-temperature / high-pressure refrigerant compressed in the compression unit (40) can be discharged to the outside of the case (10) through the refrigerant discharge pipe (14).

[0089] A base (15) supporting the case (10) may be provided at the bottom of the lower case (12). The reciprocating compressor (1) may be installed vertically with respect to the support surface by the base (15).

[0090] Fig. 2 is a cross-sectional view showing a reciprocating compressor (1) according to one or more embodiments of the present disclosure. Fig. 3 is a partial cross-sectional view showing an enlarged view of the main components of the reciprocating compressor (1) of Fig. 2.

[0091] Referring to FIGS. 2 and 3, a reciprocating compressor (1) according to one or more embodiments of the present disclosure may include a case (10) and a motor (20).

[0092] The case (10) forms the exterior of the reciprocating compressor (1) and may be formed as a sealed container. A motor (20) may be installed inside the case (10). The case (10) may include a lower case (12) and an upper case (11) covering the upper portion of the lower case (12).

[0093] The case (10) is formed by combining an upper case (11) and a lower case (12), and the interior of the case (10) can be sealed except for the refrigerant inlet pipe (13) and the refrigerant discharge pipe (14). That is, the refrigerant can be introduced into the interior of the case (10) only through the refrigerant inlet pipe (13), and can be discharged to the exterior of the case (10) only through the refrigerant discharge pipe (14).

[0094] A reservoir (16) for containing oil or lubricating oil (hereinafter referred to as “oil”) may be provided at the bottom of the lower case (12).

[0095] The motor (20) is installed inside the case (11) and may include a stator (21) and a rotor (22). The stator (21) is installed to be fixed to the case (11). The rotor (22) may be installed to rotate with respect to the stator (21).

[0096] In the present embodiment, the rotor (22) is installed on the outside of the stator (21). That is, the stator (21) is installed on the inside of the rotor (22). Therefore, the rotor (22) can rotate on the outside of the stator (21) with the stator (21) as the center. As another example, the rotor (22) can be installed to rotate on the inside of the stator (21).

[0097] The reciprocating compressor (1) may further include a bearing block (30) and a compression unit (40).

[0098] A bearing block (30) is installed inside the case (10). A motor (20) may be installed at the bottom of the bearing block (30), and a compression unit (40) may be installed at the top of the bearing block (30).

[0099] The bearing block (30) can be installed on the bottom of the lower case (12). The bearing block (30) can be supported by a pair of elastic supports (17) installed on the bottom of the lower case (12).

[0100] The bearing block (30) may include a fixed shaft (31). The fixed shaft (31) may be formed to extend vertically downward from the lower surface of the bearing block (30). The fixed shaft (31) may be formed in a cylindrical shape.

[0101] A shaft hole (32) may be formed inside the fixed shaft (31). The shaft hole (32) may be formed with a circular cross-section. The shaft hole (32) is formed to vertically penetrate the fixed shaft (31) and the bearing block (30).

[0102] A stator (21) is installed on the outer surface of the fixed shaft (31), and a drive shaft (50) is inserted into the shaft hole (32) of the fixed shaft (31).

[0103] The inner surface of the shaft hole (32) is surface-processed to function as a bearing that supports the rotation of the drive shaft (50). Therefore, the drive shaft (50) can rotate relative to the fixed shaft (31) while being inserted into the shaft hole (32).

[0104] The bearing block (30) may include a pair of legs (35) extending downward from the lower surface. The pair of legs (35) may be formed symmetrically around a fixed shaft (31). That is, a fixed shaft (31) may be formed between the pair of legs (35).

[0105] The lower surfaces of a pair of legs (35) may be supported by a pair of elastic supports (17). The upper surfaces of the elastic supports (17) may be fixed to the lower surfaces of the legs (35), and the lower surfaces of the elastic supports (17) may be fixed to the bottom of the lower casing (12). Each of the pair of elastic supports (17) may be formed of a coil spring.

[0106] The motor (20) may be installed at the bottom of the bearing block (30). The motor (20) may be configured to generate rotational force to operate the compression unit (40). The motor (20) may include a stator (21) and a rotor (22).

[0107] The stator (21) can be fixed to the lower surface of the bearing block (30). The stator (21) can be composed of a stator core and a coil. The stator core can be formed by laminating press-processed iron plates.

[0108] The rotor (22) is installed on the outside of the stator (21). That is, the stator (21) is installed on the inside of the rotor (22). Therefore, the rotor (22) can rotate on the outside of the stator (21) with the stator (21) as the center.

[0109] The rotor (22) may be formed in a cylindrical container shape. In other words, the rotor (22) may be formed in a hollow cylindrical shape with a closed bottom and an open top. A stator (21) may be accommodated inside the rotor (22). A plurality of permanent magnets (23) are installed on the outer circumference of the rotor (22). The plurality of permanent magnets (23) may be arranged at regular intervals in the circumferential direction of the rotor (22).

[0110] The compression section (40) is formed so as to compress and discharge the refrigerant introduced through the refrigerant inlet pipe (13). The compression section (40) may be provided on the upper surface of the bearing block (30).

[0111] The compression unit (40) may include a cylinder block (41), a piston (43), and a connecting rod (45).

[0112] A cylinder block (41) is formed on the upper surface of the bearing block (30). A compression chamber (42) having a circular cross-section is formed inside the cylinder block (41). An inlet valve and a discharge valve are provided on the outer end of the cylinder block (41).

[0113] A piston (43) is inserted into the compression chamber (42) of the cylinder block (41). The piston (43) is formed to reciprocate in a straight line for a certain distance along the inner surface of the compression chamber (42) of the cylinder block (41).

[0114] The piston (43) is connected to one end of a connecting rod (45). The other end of the connecting rod (45) is connected to a crankshaft (52) of a drive shaft (50). Therefore, when the drive shaft (50) rotates, the piston (43) can perform a linear reciprocating motion in the compression chamber (42) of the cylinder block (41) by the crankshaft (52) and the connecting rod (45). That is, the rotational motion of the drive shaft (50) can be converted into a linear reciprocating motion of the piston (43) by the crankshaft (52) of the drive shaft (50) and the connecting rod (45).

[0115] When the piston (43) makes a linear reciprocating motion in the compression chamber (42) of the cylinder block (41), the refrigerant can be introduced into the compression chamber (42) through the inlet valve, compressed, and then discharged outside the compression chamber (42) through the discharge valve.

[0116] Referring to FIGS. 2 and 3, the drive shaft (50) can be fixed to the center of the rotor (22). Therefore, when the rotor (22) rotates, the drive shaft (50) can rotate integrally with the rotor (22).

[0117] The drive shaft (50) is inserted into the shaft hole (32) of the fixed shaft (31) of the bearing block (30). The drive shaft (50) is rotatably supported by the shaft hole (32). Therefore, when the rotor (22) rotates, the drive shaft (50) can rotate inside the shaft hole (32) of the fixed shaft (31).

[0118] A head portion (51) is provided at the top of the drive shaft (50). The head portion (51) is formed to have a diameter larger than the diameter of the drive shaft (50). The head portion (51) is formed to rotate integrally with the drive shaft (50).

[0119] A bearing (39) is installed between the head portion (51) and the upper surface of the bearing block (30). Therefore, when the driving shaft (50) rotates, the head portion (51) can also rotate with respect to the upper surface of the bearing block (30).

[0120] A crank shaft (52) is provided on the upper surface of the head portion (51). The crank shaft (52) is formed perpendicular to the upper surface of the head portion (51). The crank shaft (52) is formed to be eccentric with the drive shaft (50). That is, the center line of the drive shaft (50) and the center line of the crank shaft (52) are spaced apart from each other by a certain distance. A connecting rod (45) can be connected to the crank shaft (52).

[0121] An oil groove (521) may be formed on the upper side of the crank shaft (52). The oil groove (521) may be formed at a certain depth on the upper surface of the crank shaft (52).

[0122] The lower end of the drive shaft (50) protrudes below the rotor (22) and can be immersed in oil contained in the oil tank (16).

[0123] The reciprocating compressor (1) may include a primary oil pump (60) and a secondary oil pump (70). The primary oil pump (60) and the secondary oil pump (70) are installed at the lower portion of the drive shaft (50) and are formed to pump oil contained in the oil reservoir (16) of the case (10). The primary oil pump (60) and the secondary oil pump (70) are installed at the lower portion of the drive shaft (50) protruding below the rotor (22).

[0124] The drive shaft (50), the primary oil pump (60), and the secondary oil pump (70) can form a drive shaft assembly.

[0125] Hereinafter, with reference to FIGS. 4 to 7, a drive shaft assembly according to one or more embodiments of the present disclosure will be described in detail.

[0126] FIG. 4 is a perspective view showing a drive shaft assembly of a reciprocating compressor (1) according to one or more embodiments of the present disclosure. FIG. 5 is an exploded perspective view of the drive shaft assembly of FIG. 4. FIG. 6 is a cross-sectional view of the drive shaft assembly of FIG. 4. FIG. 7 is a perspective view showing a secondary oil pump (70) of the drive shaft assembly of FIG. 4.

[0127] Referring to FIGS. 4 to 7, the drive shaft assembly may include a drive shaft (50), a primary oil pump (60), and a secondary oil pump (70).

[0128] The drive shaft (50) is formed to rotate integrally with the rotor (22) of the motor (20) to operate the compression unit (40).

[0129] A primary oil pump (60) and a secondary oil pump (70) may be installed at the lower portion of the drive shaft (50). The lower portion of the drive shaft (50) on which the primary oil pump (60) and the secondary oil pump (70) are installed is integrally connected to the rotor (22). Specifically, a portion of the drive shaft (50) on the upper side of the secondary oil pump (70) installed at the lower portion of the drive shaft (50) is integrally connected to the rotor (22). The primary oil pump (60) and the secondary oil pump (70) form a dual oil pump that pumps oil contained in the oil reservoir (16).

[0130] The drive shaft (50) may include a cavity (55), a first oil supply path (53), and a second oil supply path (54).

[0131] A cavity (55) may be formed at the lower end of the drive shaft (50). The cavity (55) may be formed at a certain depth on the lower surface of the drive shaft (50). The cavity (55) may be formed as a hole having a circular cross-section. A primary oil pump (60) may be inserted into the cavity (55).

[0132] Hereinafter, the part of the drive shaft (50) where the cavity (55) is formed is referred to as the lower part of the drive shaft (50), and the part of the drive shaft (50) above the cavity (55), i.e., the part of the drive shaft (50) between the cavity (55) and the head portion (51), is referred to as the upper part of the drive shaft (50).

[0133] The first oil supply path (53) may be formed as a spiral groove on the outer surface of the drive shaft (50). The first oil supply path (53) may be formed as a groove having a certain width and depth on the outer surface of the upper portion of the drive shaft (50).

[0134] A first oil inlet (531) may be formed at the bottom of the first oil supply path (53). The first oil inlet (531) may penetrate the outer surface of the drive shaft (50) and communicate with the cavity (55). The first oil inlet (531) may be formed adjacent to the upper end of the cavity (55). Accordingly, oil in the cavity (55) may flow into the first oil supply path (53) through the first oil inlet (531).

[0135] A first oil outlet (532) may be formed at the upper end of the first oil supply passage (53). The first oil outlet (532) is connected to an oil passage (522) formed at the bottom of an oil groove (521) of the crank shaft (52). Therefore, the first oil supply passage (53) is connected to the oil groove (521) of the crank shaft (52) through the first oil outlet (532) and the oil passage (522).

[0136] The oil passage (522) is formed to be inclined with respect to the longitudinal direction of the crank shaft (52). Since the oil passage (522) is inclined, when the drive shaft (50) rotates, the oil can move to the oil groove (521) of the crank shaft (52) by centrifugal force.

[0137] The second oil supply path (54) is formed to vertically penetrate the drive shaft (50). Specifically, the second oil supply path (54) is formed to communicate the upper end of the cavity (55) and the upper surface of the head portion (51). The second oil supply path (54) is formed to be inclined with respect to the longitudinal direction of the drive shaft (50). Since the second oil supply path (54) is formed to be inclined, when the drive shaft (50) rotates, the oil in the cavity (55) can move to the upper side of the head portion (51) by centrifugal force.

[0138] The primary oil pump (60) can be installed at the bottom of the drive shaft (50). Specifically, the primary oil pump (60) is installed so that the upper part is inserted into the cavity (55) of the drive shaft (50) and the lower part is immersed in the oil of the oil tank (16).

[0139] The primary oil pump (60) may be formed in a cylindrical shape. The diameter of the primary oil pump (60) is formed to be smaller than the diameter of the cavity (55) of the drive shaft (50). Therefore, a certain gap is provided between the inner surface of the cavity (55) of the primary oil pump (60) and the drive shaft (50). For example, a gap of 0.1 mm to 0.15 mm may be formed between the outer surface of the primary oil pump (60) and the inner surface of the cavity (55) of the drive shaft (50).

[0140] A spiral groove (61) may be formed on the outer surface of the primary oil pump (60). This spiral groove (61) forms a primary oil path. Accordingly, a spiral primary oil path (61) is provided between the primary oil pump (60) and the cavity (55) of the drive shaft (50). Accordingly, when the drive shaft (50) rotates, the oil in the oil reservoir (16) moves upward along the primary oil path (61) due to viscous friction with the inner surface of the cavity (55) of the rotating drive shaft (50).

[0141] The spiral direction of the spiral groove of the primary oil path (61) can be formed in the opposite direction to the spiral direction of the first oil supply path (53) of the drive shaft (50).

[0142] The primary oil pump (60) may include a coupling projection (63). The coupling projection (63) may be formed to protrude from the lower surface of the primary oil pump (60). The coupling projection (63) may be formed in a cylindrical shape. A screw thread (65) may be formed on the outer circumferential surface of the coupling projection (63). In other words, the coupling projection (63) may be formed as a male screw.

[0143] A through hole (64) through which a metal wire (80) passes may be formed in the coupling protrusion (63). Both ends of the metal wire (80) may be fixed to the lower case (12). Since the metal wire (80) is fixed to the lower case (12), the primary oil pump (60) coupled to the metal wire (80) is also fixed to the case (10). Therefore, when the drive shaft (50) rotates, the primary oil pump (60) does not rotate and remains fixed.

[0144] The secondary oil pump (70) is installed at the lower portion of the drive shaft (50). The secondary oil pump (70) may be installed on the outside of the primary oil pump (60). That is, the secondary oil pump (70) may be installed to surround the primary oil pump (60). The secondary oil pump (70) may be installed concentrically with the primary oil pump (60). A secondary oil passage (70a) is formed between the outer surface of the lower portion of the drive shaft (50) and the secondary oil pump (70).

[0145] The secondary oil path (70a) may be formed by a spiral groove (57). The diameter of the spiral groove (57) forming the secondary oil path (70a) is larger than the diameter of the spiral groove forming the primary oil path (61) of the primary oil pump (60). The secondary oil path (70a) may be formed around the primary oil path (61).

[0146] The secondary oil path (70a) may be formed as a spiral groove (57) formed on the outer surface of the lower portion of the drive shaft (50). The spiral groove (57) may be formed at a certain length from the lower end of the drive shaft (50).

[0147] The spiral direction of the spiral groove (57) of the secondary oil passage (70a) formed on the outer surface of the lower portion of the drive shaft (50) is formed to be the same as the spiral direction of the first oil supply passage (53) formed on the outer surface of the upper portion of the drive shaft (50). Therefore, when the drive shaft (50) rotates, the oil in the oil reservoir (16) moves upward along the spiral groove (57) of the rotating drive shaft (50), i.e., the secondary oil passage (70a), due to viscous frictional force.

[0148] The lower end of the drive shaft (50) is inserted into the secondary oil pump (70), and the secondary oil pump (70) can be formed to be coupled with the primary oil pump (60). When the secondary oil pump (70) is coupled to the primary oil pump (60), since the primary oil pump (60) is fixed to the case (10), the secondary oil pump (70) is also fixed to the case (10). Therefore, even if the drive shaft (50) rotates, the secondary oil pump (70) does not rotate.

[0149] The drive shaft (50) may include a communication hole (59). The communication hole (59) is formed to communicate the outer surface of the lower portion of the drive shaft (50) with the cavity (55). In other words, the communication hole (59) may be formed to communicate the primary oil passage (61) and the secondary oil passage (70a) at the lower portion of the drive shaft (50). The communication hole (59) may be formed below the first oil inlet (531) of the first oil supply passage (53) at the outer surface of the drive shaft (50).

[0150] The upper end of the secondary oil passage (70a) may be formed lower than the upper end of the secondary oil pump (70). If the upper end of the secondary oil passage (70a) is positioned higher than the upper end of the secondary oil pump (70), the oil supplied by the secondary oil pump (70) may leak out to the outside. Therefore, the upper end of the secondary oil passage (70a) is positioned lower than the upper end of the secondary oil pump (70).

[0151] The upper end of the secondary oil passage (70a) may be formed to correspond to the communication hole (59). That is, the communication hole (59) is formed at a position corresponding to the upper end of the secondary oil passage (70a) so that oil supplied through the secondary oil passage (70a) can flow into the cavity (55) of the drive shaft (50) through the communication hole (59). Accordingly, the communication hole (59) is located below the upper end of the secondary oil pump (70).

[0152] Referring to FIGS. 2 and 3, the secondary oil pump (70) is installed at the lower end of the drive shaft (50). The secondary oil pump (70) may be installed so that its upper end is adjacent to the lower end of the rotor (22). At this time, the secondary oil pump (70) may be installed as close as possible to the lower end of the rotor (22) without coming into contact with the lower end of the rotor (22) so as not to interfere with the rotation of the rotor (22). The secondary oil pump (70) is installed so as to be immersed in the oil contained in the oil reservoir (16) at the lower end of the case (10). At this time, the upper end of the secondary oil pump (70) is installed so as to be located above the surface (OS) of the oil contained in the oil reservoir (16), i.e., the oil surface.

[0153] Accordingly, the communication hole (59) of the drive shaft (50) can be located below the rotor (22). In addition, the secondary oil path (70a) of the secondary oil pump (70) can also be located below the rotor (22).

[0154] The secondary oil pump (70) may be formed in the shape of a cylindrical container with a bottom. That is, the secondary oil pump (70) may be formed in the shape of a hollow cylinder with an open top and a closed bottom.

[0155] The inner diameter of the secondary oil pump (70) is formed to be larger than the outer diameter of the drive shaft (50). For example, the gap between the inner surface of the secondary oil pump (70) and the outer surface of the drive shaft (50) may be 0.1 mm to 0.15 mm.

[0156] A coupling hole (73) may be formed in the bottom (701) of the secondary oil pump (70). The coupling hole (73) may be formed in the center of the bottom (701) of the secondary oil pump (70).

[0157] The coupling hole (73) is formed so as to be coupled with the coupling projection (63) of the primary oil pump (60). The coupling hole (73) may be formed with a female screw. That is, a female screw corresponding to the male screw (65) of the coupling projection (63) of the primary oil pump (60) may be formed on the inner circumferential surface of the coupling hole (73). Accordingly, the coupling projection (63) of the primary oil pump (60) and the coupling hole (73) of the secondary oil pump (70) may be screw-coupled.

[0158] The secondary oil pump (70) may include a plurality of oil inlets (72). The plurality of oil inlets (72) may be formed at the bottom (701) of the secondary oil pump (70). The plurality of oil inlets (72) may be formed around a coupling hole (73). The plurality of oil inlets (72) may be formed at regular intervals around the coupling hole (73).

[0159] When the secondary oil pump (70) is immersed in the oil contained in the oil tank (16), the oil in the oil tank (16) can flow into the internal space of the secondary oil pump (70) through a plurality of oil inlets (72).

[0160] As another example, as illustrated in FIG. 8, a plurality of oil inlets (72) may be formed on the side (702) of the secondary oil pump (70).

[0161] FIG. 8 is a perspective view showing a secondary oil pump (70) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure.

[0162] Referring to Fig. 8, the secondary oil pump (70) may be formed in the shape of a cylindrical container with a bottom. That is, the secondary oil pump (70) may be formed in the shape of a hollow cylinder with an open top and a closed bottom.

[0163] A coupling hole (73) may be formed in the bottom (701) of the secondary oil pump (70). The coupling hole (73) may be formed in the center of the bottom (701) of the secondary oil pump (70).

[0164] The coupling hole (73) is formed so as to be coupled with the coupling projection (63) of the primary oil pump (60). The coupling hole (73) may be formed with a female screw. That is, a female screw corresponding to the male screw (65) of the coupling projection (63) of the primary oil pump (60) may be formed on the inner circumferential surface of the coupling hole (73). Accordingly, the coupling projection (63) of the primary oil pump (60) and the coupling hole (73) of the secondary oil pump (70) may be screw-coupled.

[0165] A plurality of oil inlets (72) may be formed on the side surface (702) of the secondary oil pump (70). That is, the plurality of oil inlets (72) may be formed on the outer surface of the cylindrical container. The plurality of oil inlets (72) may be formed to penetrate the outer surface (702) and the inner surface (703) of the cylindrical container. The plurality of oil inlets (72) may be formed at regular intervals along the outer surface of the secondary oil pump (70).

[0166] The secondary oil pump (70) can be installed so that multiple oil inlets (72) are immersed in the oil contained in the oil reservoir (16). When the secondary oil pump (70) is immersed in the oil of the oil reservoir (16), the oil of the oil reservoir (16) can flow into the internal space of the secondary oil pump (70) through the multiple oil inlets (72).

[0167] As another example, as illustrated in FIG. 9, a plurality of oil inlets (72) may be formed on the bottom (701) and side (702) of the secondary oil pump (70).

[0168] FIG. 9 is a perspective view showing a secondary oil pump (70) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure.

[0169] Referring to Fig. 9, the secondary oil pump (70) may be formed in the shape of a cylindrical container with a bottom. That is, the secondary oil pump (70) may be formed in the shape of a hollow cylinder with an open top and a closed bottom.

[0170] A coupling hole (73) may be formed in the bottom (701) of the secondary oil pump (70). The coupling hole (73) may be formed in the center of the bottom (701) of the secondary oil pump (70).

[0171] The coupling hole (73) is formed so as to be coupled with the coupling projection (63) of the primary oil pump (60). The coupling hole (73) may be formed with a female screw. That is, a female screw corresponding to the male screw (65) of the coupling projection (63) of the primary oil pump (60) may be formed on the inner circumferential surface of the coupling hole (73). Accordingly, the coupling projection (63) of the primary oil pump (60) and the coupling hole (73) of the secondary oil pump (70) may be screw-coupled.

[0172] The secondary oil pump (70) may include a plurality of oil inlets (72). The plurality of oil inlets (72) may be formed on the bottom (701) and the side (702) of the secondary oil pump (70).

[0173] Specifically, some of the plurality of oil inlets (72) may be formed in the bottom (701) of the secondary oil pump (70). Some of the plurality of oil inlets (72) formed in the bottom (701) of the secondary oil pump (70) may be formed around the coupling hole (73). Some of the plurality of oil inlets (72) may be formed at regular intervals around the coupling hole (73).

[0174] The remainder of the plurality of oil inlets (72) may be formed on the side surface (702) of the secondary oil pump (70). That is, the remainder of the plurality of oil inlets (72) may be formed on the outer surface of the cylindrical container. The remainder of the plurality of oil inlets (72) may be formed to penetrate the outer surface and the inner surface of the cylindrical container. The remainder of the plurality of oil inlets (72) may be formed at regular intervals along the outer surface of the secondary oil pump (70).

[0175] The secondary oil pump (70) can be installed so that a plurality of oil inlets (72) are immersed in the oil contained in the oil reservoir (16). When the secondary oil pump (70) is immersed in the oil of the oil reservoir (16), the oil of the oil reservoir (16) can flow into the internal space of the secondary oil pump (70) through the plurality of oil inlets (72) formed on the bottom (701) and side (702) of the secondary oil pump (70).

[0176] Hereinafter, oil supply by a reciprocating compressor (1) according to one or more embodiments of the present disclosure having the above-described structure will be described in detail with reference to FIGS. 2 to 6, FIG. 34, and FIG. 35.

[0177] Fig. 34 is a drawing showing the movement of oil by rotation of a drive shaft (50) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure. Fig. 35 is an enlarged cross-sectional view of portion A of Fig. 34.

[0178] When the drive shaft (50) rotates integrally with the rotor (22), the oil contained in the oil tank (16) can be supplied to the upper side of the drive shaft (50) by the primary oil pump (60) and the secondary oil pump (70).

[0179] Specifically, when the drive shaft (50) rotates in one direction (R), the oil contained in the oil reservoir (16) can flow into the secondary oil pump (70) through the lower portion of the secondary oil pump (70). For example, the oil in the oil reservoir (16) can flow into the secondary oil pump (70) through a plurality of oil inlets (72) formed at the lower portion of the secondary oil pump (70).

[0180] A portion of the oil introduced into the internal space of the secondary oil pump (70) can be supplied to the upper portion of the cavity (55) along the primary oil path (61) formed between the inner surface of the cavity (55) of the primary oil pump (60) and the drive shaft (50) (see F1 of FIGS. 34 and 35).

[0181] In addition, the remainder of the oil that has flowed into the internal space of the secondary oil pump (70) moves upward along the secondary oil passage (70a) formed between the inner surface of the secondary oil pump (70) and the outer surface of the drive shaft (50), and can flow into the interior of the cavity (55) through the communication hole (59) (see F2 of FIGS. 34 and 35). At this time, the spiral direction of the spiral groove (57) forming the secondary oil passage (70a) formed on the outer surface of the lower portion of the drive shaft (50) is the same as the spiral direction of the first oil supply passage (53) formed on the outer surface of the upper portion of the drive shaft (50), so that when the drive shaft (50) rotates, the oil that has flowed into the interior of the secondary oil pump (70) moves upward along the secondary oil passage (70a).

[0182] Oil flowing into the cavity (55) through the communication hole (59) can move to the upper part of the cavity (55) together with oil moving along the primary oil path (61).

[0183] Therefore, when the drive shaft (50) rotates, the oil in the oil tank (16) can be supplied to the upper part of the cavity (55) by the primary oil pump (60) and the secondary oil pump (70).

[0184] A portion of the oil supplied to the upper portion of the joint (55) moves to the first oil supply path (53) through the first oil inlet (531). Some of the oil may be supplied between the outer surface of the drive shaft (50) and the inner surface of the fixed shaft (31) through the first oil supply path (53). Some of the oil that has moved to the upper portion of the first oil supply path (53) may be supplied to the oil groove (521) of the crankshaft (52) through the first oil outlet (532) and the oil passage (522). The oil supplied to the oil groove (521) may be supplied to the crankshaft (52) and the connecting rod (45).

[0185] Additionally, the remainder of the oil supplied to the upper portion of the joint (55) can be supplied to the upper portion of the drive shaft (50), i.e., the upper surface of the head portion (51), through the second oil supply path (54). The oil supplied to the upper surface of the head portion (51) can be supplied to the bearing (39) installed in the head portion (51).

[0186] As described above, the reciprocating compressor (1) according to one or more embodiments of the present disclosure supplies oil from the oil reservoir (16) to the internal components by two oil pumps, i.e., a primary oil pump (60) installed inside the cavity (55) of the drive shaft (50) and a secondary oil pump (70) installed outside the cavity (55) of the drive shaft (50), so that sufficient oil can be supplied to the internal components of the reciprocating compressor (1) even when the reciprocating compressor (1) operates at a low speed.

[0187] In the above, the case where the secondary oil passage (70a) is formed on the outer surface of the drive shaft (50) has been described. However, as another example, the secondary oil passage (70a) may be formed on the inner surface of the secondary oil pump (70).

[0188] Hereinafter, a drive shaft assembly having such a structure will be described in detail with reference to FIGS. 10 to 13.

[0189] FIG. 10 is a perspective view showing a drive shaft assembly of a reciprocating compressor (1) according to one or more embodiments of the present disclosure. FIG. 11 is an exploded perspective view of the drive shaft assembly of FIG. 10. FIG. 12 is a cross-sectional view of the drive shaft assembly of FIG. 10. FIG. 13 is a perspective view showing a secondary oil pump (70) of the drive shaft assembly of FIG. 10.

[0190] Referring to FIGS. 10 to 13, the drive shaft assembly may include a drive shaft (50), a primary oil pump (60), and a secondary oil pump (70).

[0191] The drive shaft (50) is formed to rotate integrally with the rotor (22) of the motor (20) to operate the compression unit (40).

[0192] A primary oil pump (60) and a secondary oil pump (70) may be installed at the lower portion of the drive shaft (50). The lower portion of the drive shaft (50) on which the primary oil pump (60) and the secondary oil pump (70) are installed is integrally connected to the rotor (22). Specifically, the portion of the drive shaft (50) on the upper side of the secondary oil pump (70) installed at the lower portion of the drive shaft (50) is integrally connected to the rotor (22).

[0193] The drive shaft (50) may include a cavity (55), a first oil supply path (53), and a second oil supply path (54). The cavity (55), the first oil supply path (53), and the second oil supply path (54) of the drive shaft (50) are the same as those of the drive shaft (50) according to the above-described embodiment, and thus a detailed description thereof will be omitted.

[0194] The primary oil pump (60) can be installed at the bottom of the drive shaft (50). Specifically, the primary oil pump (60) is installed so that the upper portion is inserted into the cavity (55) of the drive shaft (50), and the lower portion is immersed in the oil contained in the oil tank (16). Since the primary oil pump (60) is the same as the above-described embodiment, a detailed description thereof will be omitted.

[0195] The secondary oil pump (70) is installed at the lower portion of the drive shaft (50). The secondary oil pump (70) may be installed on the outside of the primary oil pump (60). That is, the secondary oil pump (70) may be installed to surround the primary oil pump (60). The secondary oil pump (70) may be installed concentrically with the primary oil pump (60). A secondary oil passage (70a) is formed between the outer surface of the lower portion of the drive shaft (50) and the secondary oil pump (70).

[0196] The secondary oil passage (70a) may be formed as a spiral groove (71). The diameter of the spiral groove (71) forming the secondary oil passage (70a) is larger than the diameter of the spiral groove forming the primary oil passage (61) of the primary oil pump (60). The secondary oil passage (70a) may be formed around the primary oil passage (61).

[0197] The secondary oil path (70a) may be formed as a spiral groove (71) formed on the inner surface (703) of the secondary oil pump (70). The spiral direction of the spiral groove (71), which is the secondary oil path (70a) formed on the inner surface (703) of the secondary oil pump (70), may be formed in the opposite direction to the spiral direction of the first oil supply path (53) formed on the outer surface of the upper portion of the drive shaft (50). Therefore, when the drive shaft (50) rotates, the oil in the oil reservoir (16) moves upward along the spiral groove (71) formed on the inner surface of the secondary oil pump (70), i.e., the secondary oil path (70a), due to viscous frictional force with the outer surface of the rotating drive shaft (50).

[0198] The lower end of the drive shaft (50) is inserted into the secondary oil pump (70), and the secondary oil pump (70) can be formed to be coupled with the primary oil pump (60). When the secondary oil pump (70) is coupled to the primary oil pump (60), since the primary oil pump (60) is fixed to the case (10), the secondary oil pump (70) is also fixed to the case (10). Therefore, even if the drive shaft (50) rotates, the secondary oil pump (70) does not rotate.

[0199] The drive shaft (50) may include a communication hole (59). The communication hole (59) is formed to communicate the outer surface of the lower portion of the drive shaft (50) with the cavity (55). In other words, the communication hole (59) may be formed to communicate the primary oil passage (61) and the secondary oil passage (70a) at the lower end of the drive shaft (50). The communication hole (59) may be formed below the first oil inlet (531) of the first oil supply passage (53) on the outer surface of the drive shaft (50).

[0200] The upper end of the secondary oil passage (70a) may be formed lower than the upper end of the secondary oil pump (70). If the upper end of the secondary oil passage (70a) is positioned higher than the upper end of the secondary oil pump (70), the oil supplied by the secondary oil pump (70) may leak out to the outside.

[0201] The upper end of the secondary oil passage (70a) may be formed to correspond to the communication hole (59). That is, the communication hole (59) is formed at a position corresponding to the upper end of the secondary oil passage (70a) so that oil supplied through the secondary oil passage (70a) can flow into the cavity (55) of the drive shaft (50) through the communication hole (59). Accordingly, the communication hole (59) is located below the upper end of the secondary oil pump (70).

[0202] The secondary oil pump (70) may be formed in the shape of a cylindrical container with a bottom. That is, the secondary oil pump (70) may be formed in the shape of a hollow cylinder with an open top and a closed bottom.

[0203] The inner diameter of the secondary oil pump (70) is formed to be larger than the outer diameter of the drive shaft (50). For example, the gap between the inner surface of the secondary oil pump (70) and the outer surface of the drive shaft (50) may be 0.1 mm to 0.15 mm.

[0204] A spiral groove (71) may be formed on the inner surface of the secondary oil pump (70). This spiral groove (71) forms a secondary oil path (70a).

[0205] A coupling hole (73) may be formed in the bottom (701) of the secondary oil pump (70). The coupling hole (73) may be formed in the center of the bottom (701) of the secondary oil pump (70).

[0206] The coupling hole (73) is formed so as to be coupled with the coupling projection (63) of the primary oil pump (60). The coupling hole (73) may be formed with a female screw. That is, a female screw corresponding to the male screw (65) of the coupling projection (63) of the primary oil pump (60) may be formed on the inner circumferential surface of the coupling hole (73). Accordingly, the coupling projection (63) of the primary oil pump (60) and the coupling hole (73) of the secondary oil pump (70) may be screw-coupled.

[0207] The secondary oil pump (70) may include a plurality of oil inlets (72). The plurality of oil inlets (72) may be formed around a coupling hole (73) in the bottom (701) of the secondary oil pump (70). The plurality of oil inlets (72) may be formed at regular intervals around the coupling hole (73).

[0208] When the secondary oil pump (70) is immersed in the oil tank (16), oil in the oil tank (16) can flow into the internal space of the secondary oil pump (70) through multiple oil inlets (72).

[0209] In the above, the case where the primary oil pump (60) and the secondary oil pump (70) are connected by screw connection has been described, but the connection of the primary oil pump (60) and the secondary oil pump (70) is not limited to this. For example, the primary oil pump (60) and the secondary oil pump (70) can be connected by various connection methods such as press-fit connection, one-touch connection, insertion connection, etc.

[0210] Hereinafter, various methods of combining the primary oil pump (60) and the secondary oil pump (70) will be described with reference to FIGS. 14 to 18.

[0211] FIG. 14 is a cross-sectional perspective view showing a state in which a primary oil pump (60) and a secondary oil pump (70) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure are combined.

[0212] Referring to Fig. 14, the primary oil pump (60) and the secondary oil pump (70) are coupled by a press-fit connection. The coupling protrusion (63) of the primary oil pump (60) is formed in a cylindrical shape, and the coupling hole (73) of the secondary oil pump (70) is formed in a circular hole. At this time, the diameter of the coupling protrusion (63) and the inner diameter of the coupling hole (73) are formed to form a force fit. Then, the primary oil pump (60) and the secondary oil pump (70) can be coupled by pressing the coupling protrusion (63) of the primary oil pump (60) into the coupling hole (73) of the secondary oil pump (70).

[0213] In this case, the coupling projection (63) of the primary oil pump (60) is pressed into and fixed in the coupling hole (73) of the secondary oil pump (70), so that the secondary oil pump (70) does not rotate relative to the primary oil pump (60).

[0214] In addition, a through hole (64) is formed at the bottom of the coupling protrusion (63) of the primary oil pump (60). A metal wire (80) fixed to the lower case (12) is inserted into the through hole (64). Therefore, even if the drive shaft (50) rotates, the primary oil pump (60) and the secondary oil pump (70) do not rotate.

[0215] FIG. 15 is a perspective view showing a state in which a primary oil pump (60) and a secondary oil pump (70) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure are combined.

[0216] Referring to Fig. 15, the primary oil pump (60) and the secondary oil pump (70) are coupled by insertion coupling. The coupling protrusion (63) of the primary oil pump (60) is formed in a square pillar shape, and the coupling hole (73) of the secondary oil pump (70) is formed in a square hole shape. The coupling hole (73) may be formed in a square pipe shape extending downward from the bottom (701) of the secondary oil pump (70).

[0217] At this time, the square pillar-shaped coupling protrusion (63) is formed to correspond to the square coupling hole (73). That is, the coupling protrusion (63) is formed to be easily inserted into the coupling hole (73) and not to rotate with respect to the coupling hole (73). Then, by inserting the coupling protrusion (63) of the primary oil pump (60) into the coupling hole (73) of the secondary oil pump (70), the primary oil pump (60) and the secondary oil pump (70) can be coupled.

[0218] At this time, since the square pillar-shaped coupling protrusion (63) of the primary oil pump (60) is inserted into the square coupling hole (73) of the secondary oil pump (70), the secondary oil pump (70) does not rotate relative to the primary oil pump (60).

[0219] In addition, a through hole (64) is formed at the bottom of the coupling protrusion (63) of the primary oil pump (60). A hole (74) corresponding to the through hole (64) is formed at the side of the square pipe forming the coupling hole (73) of the secondary oil pump (70). A metal wire (80) fixed to the lower case (12) is inserted into the hole (74) of the secondary oil pump (70) and the through hole (64) of the primary oil pump (60). Therefore, even if the drive shaft (50) rotates, the primary oil pump (60) and the secondary oil pump (70) do not rotate.

[0220] FIG. 16 is a drawing showing a state in which a primary oil pump (60) and a secondary oil pump (70) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure are combined.

[0221] Referring to Fig. 16, the primary oil pump (60) and the secondary oil pump (70) are coupled by insertion coupling. The coupling protrusion (63) of the primary oil pump (60) is formed in a columnar shape with an oval cross-section, and the coupling hole (73) of the secondary oil pump (70) is formed in an oval shape.

[0222] At this time, the coupling protrusion (63) having an oval cross-section is formed to correspond to the oval coupling hole (73). That is, the coupling protrusion (63) is formed to be easily inserted into the coupling hole (73) and not to rotate with respect to the coupling hole (73). Then, by inserting the coupling protrusion (63) of the primary oil pump (60) into the coupling hole (73) of the secondary oil pump (70), the primary oil pump (60) and the secondary oil pump (70) can be coupled.

[0223] At this time, since the coupling projection (63) of the elliptical column of the primary oil pump (60) is inserted into the elliptical coupling hole (73) of the secondary oil pump (70), the secondary oil pump (70) does not rotate with respect to the primary oil pump (60).

[0224] The primary oil pump (60) is fixed to a metal wire (80) fixed to the lower case (12). Therefore, even if the drive shaft (50) rotates, the primary oil pump (60) and the secondary oil pump (70) do not rotate.

[0225] In the above, the case where the cross-section of the coupling hole (73) of the secondary oil pump (70) into which the coupling protrusion (63) of the primary oil pump (60) is inserted is described as being a square or an oval, but the shape of the coupling hole (73) is not limited thereto. The coupling hole (73) may be formed as a polygon other than a square. For example, the coupling hole (73) may be formed as a triangle, a pentagon, etc. In this case, the coupling protrusion (63) of the primary oil pump (60) may be formed as a columnar shape having a cross-section corresponding to the coupling hole (73) of the secondary oil pump (70).

[0226] Fig. 17 is a perspective view showing a state in which a primary oil pump (60) and a secondary oil pump (70) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure are coupled. Fig. 18 is a perspective view showing a state in which the primary oil pump (60) and the secondary oil pump (70) of Fig. 17 are separated.

[0227] Referring to FIGS. 17 and 18, the primary oil pump (60) and the secondary oil pump (70) are coupled by a one-touch coupling.

[0228] The coupling projection (63) of the primary oil pump (60) may include a pair of catches (66). The coupling projection (63) is formed in a cylindrical shape. The pair of catches (66) are formed to protrude vertically outward from the outer surface of the coupling projection (63). The pair of catches (66) are formed at 180-degree intervals.

[0229] The coupling hole (73) of the secondary oil pump (70) may include a pair of insertion grooves (75) and a pair of fixing parts (76). The coupling hole (73) may be formed as a circular hole into which a coupling projection (63) is inserted.

[0230] A pair of insertion grooves (75) can be formed on the inner surface of the coupling hole (73). A pair of insertion grooves (75) are formed at 180-degree intervals on the inner surface of the coupling hole (73). A pair of insertion grooves (75) are formed so that a pair of catches (66) of a coupling protrusion (63) can pass through a pair of insertion grooves (75).

[0231] A pair of fixing parts (76) can be formed along the inner surface of the coupling hole (73) in a pair of insertion grooves (75) to a certain length. A pair of fixing parts (76) is formed so that a pair of catch parts (66) of the coupling protrusion (63) catches on a pair of fixing parts (76).

[0232] Therefore, when a pair of catches (66) of the coupling protrusion (63) are aligned with a pair of insertion grooves (75) of the coupling hole (73), the coupling protrusion (63) can be inserted into the coupling hole (73). In this state, when the coupling protrusion (63) is rotated about 90 degrees, a pair of catches (66) of the coupling protrusion (63) are caught by a pair of fixing parts (76) of the coupling hole (73). Then, the primary oil pump (60) is coupled to the secondary oil pump (70), and the primary oil pump (60) is not separated from the secondary oil pump (70). Therefore, even if the drive shaft (50) rotates, the primary oil pump (60) and the secondary oil pump (70) do not rotate.

[0233] Fig. 19 is a cross-sectional view showing a reciprocating compressor (1) according to one or more embodiments of the present disclosure. Fig. 20 is a partial cross-sectional view showing an enlarged view of the main components of the reciprocating compressor (1) of Fig. 19.

[0234] Referring to FIGS. 19 and 20, a reciprocating compressor (1) according to one or more embodiments of the present disclosure may include a case (10) and a motor (20).

[0235] The case (10) forms the exterior of the reciprocating compressor (1) and may be formed as a sealed container. A motor (20) may be installed inside the case (10). The case (10) may include a lower case (12) and an upper case (11) covering the upper portion of the lower case (12).

[0236] The case (10) is formed by combining an upper case (11) and a lower case (12), and the interior of the case (10) can be sealed except for the refrigerant inlet pipe (13) and the refrigerant discharge pipe (14). That is, the refrigerant can be introduced into the interior of the case (10) only through the refrigerant inlet pipe (13), and can be discharged to the exterior of the case (10) only through the refrigerant discharge pipe (14).

[0237] An oil storage tank (16) for containing oil may be provided at the bottom of the lower case (12).

[0238] The motor (20) is installed inside the case (10) and may include a stator (21) and a rotor (22). The stator (21) is installed to be fixed to the case (10). The rotor (22) may be installed to rotate with respect to the stator (21).

[0239] In the present embodiment, the rotor (22) is installed on the outside of the stator (21). That is, the stator (21) is installed on the inside of the rotor (22). Therefore, the rotor (22) can rotate on the outside of the stator (21) with the stator (21) as the center. As another example, the rotor (22) can be installed to rotate on the inside of the stator (21).

[0240] The reciprocating compressor (1) may include a bearing block (30) and a compression unit (40).

[0241] A bearing block (30) is installed inside the case (10). A motor (20) may be installed at the bottom of the bearing block (30), and a compression unit (40) may be installed at the top of the bearing block (30).

[0242] The bearing block (30) can be installed on the bottom of the lower case (12). The bearing block (30) can be supported by a pair of elastic supports (17) installed on the bottom of the lower case (12).

[0243] The bearing block (30) may include a fixed shaft (31). The fixed shaft (31) may be formed to extend vertically downward from the lower surface of the bearing block (30). The fixed shaft (31) may be formed in a cylindrical shape.

[0244] A shaft hole (32) may be formed inside the fixed shaft (31). The shaft hole (32) may be formed with a circular cross-section. The shaft hole (32) is formed to vertically penetrate the fixed shaft (31) and the bearing block (30).

[0245] A stator (21) is installed on the outer surface of the fixed shaft (31), and a drive shaft (50) is inserted into the shaft hole (32) of the fixed shaft (31).

[0246] The inner surface of the shaft hole (32) is surface-processed to function as a bearing that supports the rotation of the drive shaft (50). Therefore, the drive shaft (50) can rotate relative to the fixed shaft (31) while being inserted into the shaft hole (32).

[0247] The bearing block (30) may include a pair of legs (35) extending downward from the lower surface. The pair of legs (35) may be formed symmetrically around a fixed shaft (31). That is, a fixed shaft (31) may be formed between the pair of legs (35).

[0248] The lower surfaces of a pair of legs (35) may be supported by a pair of elastic supports (17). The upper surfaces of the elastic supports (17) may be fixed to the lower surfaces of the legs (35), and the lower surfaces of the elastic supports (17) may be fixed to the bottom of the lower casing (12). Each of the pair of elastic supports (17) may be formed of a coil spring.

[0249] The motor (20) may be installed at the bottom of the bearing block (30). The motor (20) may be configured to generate rotational force to operate the compression unit (40). The motor (20) may include a stator (21) and a rotor (22).

[0250] The stator (21) can be fixed to the lower surface of the bearing block (30). The stator (21) can be composed of a stator core and a coil. The stator core can be formed by laminating press-processed iron plates.

[0251] The rotor (22) is installed on the outside of the stator (21). That is, the stator (21) is installed on the inside of the rotor (22). Therefore, the rotor (22) can rotate on the outside of the stator (21) with the stator (21) as the center.

[0252] The rotor (22) may be formed in a cylindrical container shape. In other words, the rotor (22) may be formed in a hollow cylindrical shape with a closed bottom and an open top. A stator (21) may be accommodated inside the rotor (22). A plurality of permanent magnets (23) are installed on the outer circumference of the rotor (22). The plurality of permanent magnets (23) may be arranged at regular intervals in the circumferential direction of the rotor (22).

[0253] The compression section (40) is formed so as to compress and discharge the refrigerant introduced through the refrigerant inlet pipe (13). The compression section (40) may be provided on the upper surface of the bearing block (30).

[0254] The compression unit (40) may include a cylinder block (41), a piston (43), and a connecting rod (45).

[0255] A cylinder block (41) is formed on the upper surface of the bearing block (30). A compression chamber (42) having a circular cross-section is formed inside the cylinder block (41). An inlet valve and a discharge valve are provided on the outer end of the cylinder block (41).

[0256] A piston (43) is inserted into the compression chamber (42) of the cylinder block (41). The piston (43) is formed to reciprocate in a straight line for a certain distance along the inner surface of the compression chamber (42) of the cylinder block (41).

[0257] The piston (43) is connected to one end of a connecting rod (45). The other end of the connecting rod (45) is connected to a crankshaft (52) of a drive shaft (50). Therefore, when the drive shaft (50) rotates, the piston (43) can perform a linear reciprocating motion in the compression chamber (42) of the cylinder block (41) by the crankshaft (52) and the connecting rod (45). That is, the rotational motion of the drive shaft (50) can be converted into a linear reciprocating motion of the piston (43) by the crankshaft (52) of the drive shaft (50) and the connecting rod (45).

[0258] When the piston (43) makes a linear reciprocating motion in the compression chamber (42) of the cylinder block (41), the refrigerant can be introduced into the compression chamber (42) through the inlet valve, compressed, and then discharged outside the compression chamber (42) through the discharge valve.

[0259] Referring to FIGS. 19 and 20, the drive shaft (50) can be fixed to the center of the rotor (22). Therefore, when the rotor (22) rotates, the drive shaft (50) can rotate integrally with the rotor (22).

[0260] The drive shaft (50) is inserted into the shaft hole (32) of the fixed shaft (31) of the bearing block (30). The drive shaft (50) is rotatably supported by the shaft hole (32). Therefore, when the rotor (22) rotates, the drive shaft (50) can rotate in the shaft hole (32) of the fixed shaft (31).

[0261] A head portion (51) is provided at the top of the drive shaft (50). The head portion (51) is formed to have a diameter larger than the diameter of the drive shaft (50). The head portion (51) is formed to rotate integrally with the drive shaft (50).

[0262] A bearing (39) is installed between the head portion (51) and the upper surface of the bearing block (30). Therefore, when the driving shaft (50) rotates, the head portion (51) can also rotate with respect to the upper surface of the bearing block (30).

[0263] A crank shaft (52) is provided on the upper surface of the head portion (51). The crank shaft (52) is formed perpendicular to the upper surface of the head portion (51). The crank shaft (52) is formed to be eccentric with the drive shaft (50). That is, the center line of the drive shaft (50) and the center line of the crank shaft (52) are spaced apart from each other by a certain distance. A connecting rod (45) can be connected to the crank shaft (52).

[0264] An oil groove (521) may be formed on the upper side of the crank shaft (52). The oil groove (521) may be formed at a certain depth on the upper surface of the crank shaft (52).

[0265] The lower end of the drive shaft (50) protrudes below the rotor (22) and can be immersed in oil contained in the oil tank (16).

[0266] The reciprocating compressor (1) may include a primary oil pump (60) and a secondary oil pump (70). The primary oil pump (60) and the secondary oil pump (70) are installed at the lower portion of the drive shaft (50) and are formed so as to pump oil contained in the oil reservoir (16) of the case (10) to the upper portion of the drive shaft (50). The primary oil pump (60) and the secondary oil pump (70) are installed at the lower portion of the drive shaft (50) protruding below the rotor (22).

[0267] The drive shaft (50), the primary oil pump (60), and the secondary oil pump (70) can form a drive shaft assembly.

[0268] Hereinafter, with reference to FIGS. 21 to 24, a drive shaft assembly according to one or more embodiments of the present disclosure will be described in detail.

[0269] FIG. 21 is a perspective view showing a drive shaft assembly of a reciprocating compressor (1) according to one or more embodiments of the present disclosure. FIG. 22 is an exploded perspective view of the drive shaft assembly of FIG. 21. FIG. 23 is a cross-sectional view of the drive shaft assembly of FIG. 21. FIG. 24 is a perspective view showing a secondary oil pump (70) of the drive shaft assembly of FIG. 21.

[0270] Referring to FIGS. 21 to 24, the drive shaft assembly may include a drive shaft (50), a primary oil pump (60), and a secondary oil pump (70).

[0271] The drive shaft (50) is formed to rotate integrally with the rotor (22) of the motor (20) to operate the compression unit (40).

[0272] A primary oil pump (60) and a secondary oil pump (70) may be installed at the lower portion of the drive shaft (50). The lower portion of the drive shaft (50) on which the primary oil pump (60) and the secondary oil pump (70) are installed is integrally connected to the rotor (22). Specifically, a portion of the drive shaft (50) on the upper side of the secondary oil pump (70) installed at the lower portion of the drive shaft (50) is integrally connected to the rotor (22). The primary oil pump (60) and the secondary oil pump (70) form a dual oil pump that pumps oil contained in the oil reservoir (16).

[0273] The drive shaft (50) may include a cavity (55), a first oil supply path (53), and a second oil supply path (54).

[0274] A cavity (55) may be formed at the lower end of the drive shaft (50). The cavity (55) may be formed at a certain depth on the lower surface of the drive shaft (50). The cavity (55) may be formed as a hole having a circular cross-section. A primary oil pump (60) may be inserted into the cavity (55).

[0275] The part of the drive shaft (50) where the cavity (55) is formed is the lower part of the drive shaft (50), and the part of the drive shaft (50) above the cavity (55), that is, the part of the drive shaft (50) between the cavity (55) and the head portion (51), is the upper part of the drive shaft (50).

[0276] The first oil supply path (53) may be formed as a spiral groove on the outer surface of the drive shaft (50). The first oil supply path (53) may be formed as a groove having a certain width and depth on the outer surface of the upper portion of the drive shaft (50).

[0277] A first oil inlet (531) may be formed at the bottom of the first oil supply path (53). The first oil inlet (531) may penetrate the outer surface of the drive shaft (50) and communicate with the cavity (55). The first oil inlet (531) may be formed adjacent to the upper end of the cavity (55). Accordingly, oil in the cavity (55) may flow into the first oil supply path (53) through the first oil inlet (531).

[0278] A first oil outlet (532) may be formed at the upper end of the first oil supply passage (53). The first oil outlet (532) is connected to an oil passage (522) formed at the bottom of an oil groove (521) of the crank shaft (52). Therefore, the first oil supply passage (53) is connected to the oil groove (521) of the crank shaft (52) through the first oil outlet (532) and the oil passage (522).

[0279] The oil passage (522) is formed to be inclined with respect to the longitudinal direction of the crank shaft (52). Since the oil passage (522) is inclined, when the drive shaft (50) rotates, the oil can move to the oil groove (521) of the crank shaft (52) by centrifugal force.

[0280] The second oil supply path (54) is formed to vertically penetrate the drive shaft (50). Specifically, the second oil supply path (54) is formed to communicate the upper end of the cavity (55) and the upper surface of the head portion (51). The second oil supply path (54) is formed to be inclined with respect to the longitudinal direction of the drive shaft (50). Since the second oil supply path (54) is formed to be inclined, when the drive shaft (50) rotates, the oil in the cavity (55) can move to the upper side of the head portion (51) by centrifugal force.

[0281] The primary oil pump (60) can be installed at the bottom of the drive shaft (50). Specifically, the primary oil pump (60) is installed so as to be inserted into the cavity (55) of the drive shaft (50). The portion of the drive shaft (50) protruding below the rotor (22) and the lower portion of the primary oil pump (60) are installed so as to be immersed in the oil of the oil reservoir (16).

[0282] The primary oil pump (60) may be formed in a cylindrical shape. The diameter of the primary oil pump (60) is formed to be smaller than the diameter of the cavity (55) of the drive shaft (50). Therefore, a certain gap is provided between the inner surface of the cavity (55) of the primary oil pump (60) and the drive shaft (50). For example, a gap of 0.1 mm to 0.15 mm may be formed between the outer surface of the primary oil pump (60) and the inner surface of the cavity (55) of the drive shaft (50).

[0283] A spiral groove (61) may be formed on the outer surface of the primary oil pump (60). This spiral groove (61) forms a primary oil path. Accordingly, a spiral primary oil path (61) is provided between the primary oil pump (60) and the cavity (55) of the drive shaft (50). Accordingly, when the drive shaft (50) rotates, the oil in the oil reservoir (16) moves upward along the primary oil path (61) due to viscous friction with the inner surface of the cavity (55) of the rotating drive shaft (50).

[0284] The spiral direction of the spiral groove forming the primary oil path (61) can be formed in the opposite direction to the spiral direction of the first oil supply path (53) of the drive shaft (50).

[0285] The primary oil pump (60) may include a coupling projection (63). The coupling projection (63) may be formed to protrude from the lower surface of the primary oil pump (60). The coupling projection (63) may be formed in a cylindrical shape. A screw thread (65) may be formed on the outer circumferential surface of the coupling projection (63). In other words, the coupling projection (63) may be formed as a male screw.

[0286] A through hole (64) through which a metal wire (80) passes may be formed at the lower portion of the coupling protrusion (63). Both ends of the metal wire (80) inserted into the through hole (64) of the coupling protrusion (63) may be fixed to the lower case (12). Since the metal wire (80) is fixed to the lower case (12), the primary oil pump (60) coupled to the metal wire (80) is also fixed to the case (10). Therefore, when the drive shaft (50) rotates, the primary oil pump (60) does not rotate and remains fixed.

[0287] The secondary oil pump (70) is installed at the lower portion of the drive shaft (50). The secondary oil pump (70) may be installed outside the primary oil pump (60). That is, the secondary oil pump (70) may be installed to surround the primary oil pump (60). The secondary oil pump (70) may be installed to surround the lower portion of the primary oil pump (60) and the drive shaft (50).

[0288] The secondary oil pump (70) can be installed concentrically with the primary oil pump (60). A secondary oil path (70a) is formed between the outer surface of the lower end of the drive shaft (50) and the secondary oil pump (70).

[0289] The secondary oil passage (70a) may be formed by a spiral groove (57). The diameter of the spiral groove (57) forming the secondary oil passage (70a) is larger than the diameter of the spiral groove (61) of the primary oil pump (60). That is, the secondary oil passage (70a) may be formed around the primary oil passage (61).

[0290] The secondary oil path (70a) may be formed as a spiral groove (57) formed on the outer surface of the lower portion of the drive shaft (50). The spiral groove (57) may be formed at a certain length from the lower end of the drive shaft (50).

[0291] The spiral direction of the spiral groove (57) of the secondary oil passage (70a) formed on the outer surface of the lower portion of the drive shaft (50) is formed in the opposite direction to the spiral direction of the first oil supply passage (53) formed on the outer surface of the upper portion of the drive shaft (50). For example, when the spiral direction of the first oil supply passage (53) is a right-hand spiral direction, the spiral direction of the secondary oil passage (70a) is a left-hand spiral direction.

[0292] Accordingly, when the drive shaft (50) rotates, the oil contained in the oil tank (16) moves toward the lower end of the drive shaft (50), i.e., the lower end of the secondary oil passage (70a), along the spiral groove (57) of the lower end of the rotating drive shaft (50) due to viscous frictional force.

[0293] The lower end of the drive shaft (50) is inserted into the secondary oil pump (70), and the secondary oil pump (70) can be formed to be coupled with the primary oil pump (60). When the secondary oil pump (70) is coupled to the primary oil pump (60), since the primary oil pump (60) is fixed to the case (10), the secondary oil pump (70) is also fixed to the case (10). Therefore, even if the drive shaft (50) rotates, the secondary oil pump (70) does not rotate.

[0294] The upper end of the secondary oil passage (70a) may be formed to be positioned above the upper end of the secondary oil pump (70). Specifically, the upper end (57a) of the spiral groove (57) forming the secondary oil passage (70a) formed on the outer circumferential surface of the lower end of the drive shaft (50) may be formed so that the spiral groove (57) is exposed above the upper end of the secondary oil pump (70). When the upper end of the secondary oil passage (70a) is exposed above the upper end of the secondary oil pump (70), the oil in the oil reservoir (16) can smoothly flow into the secondary oil passage (70a).

[0295] The lower end of the secondary oil passage (70a) can be formed at the lower end of the drive shaft (50). Therefore, oil flowing into the upper end of the secondary oil passage (70a) can move along the secondary oil passage (70a) to the lower end of the drive shaft (50).

[0296] Referring to FIGS. 19 and 20, the secondary oil pump (70) is installed at the lower end of the drive shaft (50). The secondary oil pump (70) may be installed so that its upper end is adjacent to the lower surface of the rotor (22). At this time, the secondary oil pump (70) may be installed as close to the lower surface of the rotor (22) as possible without coming into contact with the lower surface of the rotor (22) so as not to interfere with the rotation of the rotor (22).

[0297] The secondary oil pump (70) is installed so as to be immersed in the oil contained in the oil reservoir (16) at the bottom of the case (10). The secondary oil pump (70) is installed so that the oil inlet (72) is located below the oil surface (OS) of the oil contained in the oil reservoir (16), i.e., the oil level. At this time, the upper end of the secondary oil pump (70) may be located at the same height as the oil surface (OS) or below the oil surface (OS). Accordingly, the secondary oil passage (70a) of the secondary oil pump (70) may also be located below the oil surface (OS).

[0298] The secondary oil pump (70) may be formed in the shape of a cylindrical container with a bottom. That is, the secondary oil pump (70) may be formed in the shape of a hollow cylinder with an open top and a closed bottom.

[0299] The inner diameter of the secondary oil pump (70) is formed to be larger than the outer diameter of the lower portion of the drive shaft (50). For example, the gap between the inner surface of the secondary oil pump (70) and the outer surface of the lower portion of the drive shaft (50) may be 0.1 mm to 0.15 mm.

[0300] A coupling hole (73) may be formed in the bottom (701) of the secondary oil pump (70). The coupling hole (73) may be formed in the center of the bottom (701) of the secondary oil pump (70).

[0301] The coupling hole (73) is formed so as to be coupled with the coupling projection (63) of the primary oil pump (60). The coupling hole (73) may be formed with a female screw. That is, a female screw corresponding to the male screw (65) of the coupling projection (63) of the primary oil pump (60) may be formed on the inner circumferential surface of the coupling hole (73). Accordingly, the coupling projection (63) of the primary oil pump (60) and the coupling hole (73) of the secondary oil pump (70) may be screw-coupled.

[0302] The secondary oil pump (70) may include at least one oil inlet (72). The at least one oil inlet (72) may be formed on an outer surface of the cylindrical container. The at least one oil inlet (72) may be formed to penetrate the outer surface (702) and the inner surface (703) of the cylindrical container. The at least one oil inlet (72) may be formed on an upper portion of the outer surface (702) of the secondary oil pump (70). The at least one oil inlet (72) may be formed adjacent to an upper portion of the secondary oil pump (70).

[0303] At least one oil inlet (72) may be formed to communicate with a secondary oil passage (70a). Accordingly, when the drive shaft (50) rotates, oil from the oil reservoir (16) may flow into the secondary oil passage (70a) through at least one oil inlet (72).

[0304] In the present embodiment, the secondary oil pump (70) includes two oil inlets (72), but the number of oil inlets (72) is not limited thereto.

[0305] When at least one oil inlet (72) of the secondary oil pump (70) is immersed in oil contained in the oil reservoir (16), the oil in the oil reservoir (16) can flow into the secondary oil path (70a) of the secondary oil pump (70) through the at least one oil inlet (72).

[0306] When the upper part of the secondary oil pump (70) is immersed in the oil of the oil tank (16), the oil of the oil tank (16) can flow into the secondary oil channel (70a) through at least one oil inlet (72) and the upper part of the secondary oil channel (70a) exposed above the upper part of the secondary oil pump (70). Therefore, a sufficient amount of oil can flow into the secondary oil channel (70a).

[0307] As another example, as illustrated in FIG. 25, a plurality of oil inlets (72) may be formed at the top of the secondary oil pump (70).

[0308] FIG. 25 is a perspective view showing a secondary oil pump (70) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure.

[0309] Referring to Fig. 25, the secondary oil pump (70) may be formed in the shape of a cylindrical container with a bottom. That is, the secondary oil pump (70) may be formed in the shape of a hollow cylinder with an open top and a closed bottom.

[0310] A coupling hole (73) may be formed in the bottom (701) of the secondary oil pump (70). The coupling hole (73) may be formed in the center of the bottom (701) of the secondary oil pump (70).

[0311] The coupling hole (73) is formed so as to be coupled with the coupling projection (63) of the primary oil pump (60). The coupling hole (73) may be formed with a female screw. That is, a female screw corresponding to the male screw (65) of the coupling projection (63) of the primary oil pump (60) may be formed on the inner circumferential surface of the coupling hole (73). Accordingly, the coupling projection (63) of the primary oil pump (60) and the coupling hole (73) of the secondary oil pump (70) may be screw-coupled.

[0312] At least one oil inlet (72) may be formed at the top of the secondary oil pump (70). That is, at least one oil inlet (72) may be formed as a groove of a certain depth at the top of the secondary oil pump (70). At least one oil inlet (72) may be formed to communicate with the secondary oil passage (70a).

[0313] In the embodiment illustrated in Fig. 25, three oil inlets (72) are formed at the top of the secondary oil pump (70).

[0314] The secondary oil pump (70) can be installed so that at least one oil inlet (72) is immersed in the oil contained in the oil reservoir (16). When the upper end of the secondary oil pump (70) is immersed in the oil of the oil reservoir (16), the oil of the oil reservoir (16) can flow into the secondary oil path (70a) of the secondary oil pump (70) through the at least one oil inlet (72).

[0315] As another example, as illustrated in FIG. 26, the secondary oil pump (70) may not include an oil inlet (72). That is, the oil inlet (72) may not be formed on the outer surface of the secondary oil pump (70).

[0316] Fig. 26 is a perspective view showing a secondary oil pump (70) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure. Fig. 27 is a partially enlarged cross-sectional view showing the secondary oil pump (70) of Fig. 26 submerged in a low-pressure tank.

[0317] Referring to Fig. 26, the secondary oil pump (70) may be formed in the shape of a cylindrical container with a bottom. That is, the secondary oil pump (70) may be formed in the shape of a hollow cylinder with an open top and a closed bottom.

[0318] A coupling hole (73) may be formed in the bottom (701) of the secondary oil pump (70). The coupling hole (73) may be formed in the center of the bottom (701) of the secondary oil pump (70).

[0319] The coupling hole (73) is formed so as to be coupled with the coupling projection (63) of the primary oil pump (60). The coupling hole (73) may be formed with a female screw. That is, a female screw corresponding to the male screw (65) of the coupling projection (63) of the primary oil pump (60) may be formed on the inner circumferential surface of the coupling hole (73). Accordingly, the coupling projection (63) of the primary oil pump (60) and the coupling hole (73) of the secondary oil pump (70) may be screw-coupled.

[0320] The secondary oil pump (70) does not include an oil inlet (72). That is, an oil inlet (72) is not formed on the outer surface and bottom of the secondary oil pump (70).

[0321] Referring to Fig. 27, the secondary oil pump (70) may be installed so as to be completely submerged in the oil contained in the oil reservoir (16). In other words, the secondary oil pump (70) may be installed so that the upper portion of the secondary oil pump (70) and the upper portion (57a) of the secondary oil passage (70a) exposed above the upper portion of the secondary oil pump (70) are submerged in the oil contained in the oil reservoir (16).

[0322] When the secondary oil pump (70) is completely immersed in the oil of the oil reservoir (16), the oil of the oil reservoir (16) can flow into the secondary oil passage (70a) through the gap between the upper part of the secondary oil pump (70) and the outer surface of the lower part of the drive shaft (50) and the upper part (57a) of the secondary oil passage (70a) exposed above the upper part of the secondary oil pump (70) (see arrow F).

[0323] Hereinafter, oil supply by a reciprocating compressor (1) according to one or more embodiments of the present disclosure having the above-described structure will be described in detail with reference to FIGS. 19 to 23, FIG. 36, and FIG. 37.

[0324] Fig. 36 is a drawing showing the movement of oil by rotation of a drive shaft of a reciprocating compressor according to one or more embodiments of the present disclosure. Fig. 37 is an enlarged cross-sectional view of portion B of Fig. 36.

[0325] When the drive shaft (50) rotates integrally with the rotor (22), the oil contained in the oil tank (16) can be supplied to the upper side of the drive shaft (50) by the primary oil pump (60) and the secondary oil pump (70).

[0326] Specifically, when the drive shaft (50) rotates in one direction (R), the oil contained in the oil reservoir (16) can flow into the interior of the secondary oil pump (70) through the upper portion of the secondary oil pump (70). For example, the oil in the oil reservoir (16) can flow into the secondary oil pump (70) through at least one oil inlet (72) formed in the upper portion of the secondary oil pump (70).

[0327] The oil introduced into the secondary oil pump (70) moves downward, i.e., to the bottom of the secondary oil pump (70), along the secondary oil passage (70a) formed between the inner surface of the secondary oil pump (70) and the outer surface of the lower portion of the drive shaft (50) (see F3 of FIGS. 36 and 37). At this time, the spiral direction of the spiral groove (57) forming the secondary oil passage (70a) formed on the outer surface of the lower portion of the drive shaft (50) is formed in the opposite direction to the spiral direction of the first oil supply passage (53) formed on the outer surface of the upper portion of the drive shaft (50), so that when the drive shaft (50) rotates, the oil moves toward the lower portion of the drive shaft (50) along the secondary oil passage (70a) formed on the lower portion of the drive shaft (50).

[0328] The oil that has moved to the bottom of the secondary oil pump (70) along the secondary oil passage (70a) moves to the primary oil passage (61) formed between the inner surface of the cavity (55) of the primary oil pump (60) and the drive shaft (50) through the gap between the lower end of the drive shaft (50) and the bottom of the secondary oil pump (70), and can be supplied to the upper portion of the cavity (55) along the primary oil passage (61) (see F4 of FIGS. 36 and 37). In other words, the oil in the oil reservoir (16) can move to the lower portion of the secondary oil pump (70) along the secondary oil passage (70a), and then move to the upper portion of the cavity (55) along the primary oil passage (61).

[0329] Therefore, when the drive shaft (50) rotates, the oil in the oil tank (16) can be supplied to the upper part of the cavity (55) by the primary oil pump (60) and the secondary oil pump (70).

[0330] A portion of the oil supplied to the upper portion of the joint (55) moves to the first oil supply path (53) through the first oil inlet (531). Some of the oil may be supplied between the outer surface of the drive shaft (50) and the inner surface of the fixed shaft (31) through the first oil supply path (53). Some of the oil that has moved to the upper portion of the first oil supply path (53) may be supplied to the oil groove (521) of the crankshaft (52) through the first oil outlet (532) and the oil passage (522). The oil supplied to the oil groove (521) may be supplied to the crankshaft (52) and the connecting rod (45).

[0331] Additionally, the remainder of the oil supplied to the upper portion of the joint (55) can be supplied to the upper portion of the drive shaft (50), i.e., the upper surface of the head portion (51), through the second oil supply path (54). The oil supplied to the upper surface of the head portion (51) can be supplied to the bearing (39) installed in the head portion (51).

[0332] As described above, the reciprocating compressor (1) according to one or more embodiments of the present disclosure is supplied with oil from the oil reservoir (16) by two oil pumps, i.e., a primary oil pump (60) installed inside the cavity (55) of the drive shaft (50) and a secondary oil pump (70) installed outside the cavity (55) of the drive shaft (50), so that sufficient oil can be supplied to the components of the reciprocating compressor (1) even when the reciprocating compressor (1) operates at a low speed.

[0333] In the above, the case where the secondary oil passage (70a) is formed on the outer surface of the lower portion of the drive shaft (50) has been described. However, as another example, the secondary oil passage (70a) may be formed on the inner surface of the secondary oil pump (70).

[0334] Hereinafter, a drive shaft assembly having such a structure will be described in detail with reference to FIGS. 28 to 31.

[0335] Fig. 28 is a perspective view showing a drive shaft assembly of a reciprocating compressor (1) according to one or more embodiments of the present disclosure. Fig. 29 is an exploded perspective view of the drive shaft assembly of Fig. 28. Fig. 30 is a cross-sectional view of the drive shaft assembly of Fig. 28. Fig. 31 is a perspective view showing a secondary oil pump (70) of the drive shaft assembly of Fig. 28.

[0336] Referring to FIGS. 28 to 31, the drive shaft assembly may include a drive shaft (50), a primary oil pump (60), and a secondary oil pump (70).

[0337] The drive shaft (50) is formed to rotate integrally with the rotor (22) of the motor (20) to operate the compression unit (40).

[0338] A primary oil pump (60) and a secondary oil pump (70) can be installed at the lower part of the drive shaft (50). The lower part of the drive shaft (50) where the primary oil pump (60) and the secondary oil pump (70) are installed is integrally connected to the rotor (22).

[0339] The drive shaft (50) may include a cavity (55), a first oil supply path (53), and a second oil supply path (54). The cavity (55), the first oil supply path (53), and the second oil supply path (54) of the drive shaft (50) are the same as those of the drive shaft (50) according to the above-described embodiment, and thus a detailed description thereof will be omitted.

[0340] The primary oil pump (60) can be installed at the lower portion of the drive shaft (50). Specifically, the primary oil pump (60) is installed so as to be inserted into the cavity (55) of the drive shaft (50). The portion of the drive shaft (50) protruding below the rotor (22) and the lower portion of the primary oil pump (60) are installed so as to be immersed in oil contained in the oil reservoir (16).

[0341] The primary oil pump (60) is the same as the above-described embodiment, so a detailed description is omitted.

[0342] The secondary oil pump (70) is installed at the lower portion of the drive shaft (50). The secondary oil pump (70) may be installed outside the primary oil pump (60). That is, the secondary oil pump (70) may be installed to surround the primary oil pump (60). The secondary oil pump (70) may be installed to surround the lower portion of the primary oil pump (60) and the drive shaft (50).

[0343] The secondary oil pump (70) can be installed concentrically with the primary oil pump (60). A secondary oil path (70a) is formed between the outer surface of the lower portion of the drive shaft (50) and the secondary oil pump (70).

[0344] The secondary oil path (70a) may be formed as a spiral groove (71). The diameter of the spiral groove (71) forming the secondary oil path (70a) is larger than the diameter of the spiral groove (61) of the primary oil pump (60). That is, the secondary oil path (70a) may be formed around the primary oil path (61).

[0345] The secondary oil passage (70a) may be formed as a spiral groove (71) formed on the inner surface (703) of the secondary oil pump (70). The spiral direction of the spiral groove (71), which is the secondary oil passage (70a) formed on the inner surface (703) of the secondary oil pump (70), may be formed in the same direction as the spiral direction of the first oil supply passage (53) formed on the outer surface of the upper portion of the drive shaft (50). For example, when the spiral direction of the first oil supply passage (53) is a right-hand spiral direction, the spiral direction of the secondary oil passage (70a) is also a right-hand spiral direction.

[0346] Accordingly, when the drive shaft (50) rotates, the oil in the oil tank (16) moves downward along the spiral groove (71), i.e., the secondary oil path (70a), formed on the inner surface of the secondary oil pump (70) by viscous friction with the outer surface of the rotating drive shaft (50).

[0347] The lower end of the drive shaft (50) is inserted into the secondary oil pump (70), and the secondary oil pump (70) can be formed to be coupled with the primary oil pump (60). When the secondary oil pump (70) is coupled to the primary oil pump (60), since the primary oil pump (60) is fixed to the case (10), the secondary oil pump (70) is also fixed to the case (10). Therefore, even if the drive shaft (50) rotates, the secondary oil pump (70) does not rotate.

[0348] The upper end of the secondary oil passage (70a) may be formed at the upper end of the secondary oil pump (70). That is, a groove (71a) communicating with the secondary oil passage (70a) may be formed at the upper end of the secondary oil pump (70). When the upper end of the secondary oil passage (70a) is formed at the upper end of the secondary oil pump (70), oil from the oil reservoir (16) can smoothly flow into the secondary oil passage (70a).

[0349] The lower end of the secondary oil passage (70a) may be formed to be adjacent to or in contact with the bottom of the secondary oil pump (70). Accordingly, oil introduced into the upper end of the secondary oil passage (70a) can move along the secondary oil passage (70a) to the bottom of the secondary oil pump (70).

[0350] The secondary oil pump (70) is installed at the lower end of the drive shaft (50). The secondary oil pump (70) may be installed so that its upper end is adjacent to the lower surface of the rotor (22). At this time, the secondary oil pump (70) may be installed as close as possible to the lower surface of the rotor (22) without coming into contact with the lower surface of the rotor (22) so as not to interfere with the rotation of the rotor (22).

[0351] The secondary oil pump (70) is installed so as to be immersed in the oil contained in the oil reservoir (16) at the bottom of the case (10). The secondary oil pump (70) is installed so that the oil inlet (72) is located below the oil surface (OS) of the oil contained in the oil reservoir (16), i.e., the oil level. At this time, the upper end of the secondary oil pump (70) may be located at the same height as the oil surface (OS) or below the oil surface (OS). Accordingly, the secondary oil passage (70a) of the secondary oil pump (70) may also be located below the oil surface (OS).

[0352] The secondary oil pump (70) may be formed in the shape of a cylindrical container with a bottom. That is, the secondary oil pump (70) may be formed in the shape of a hollow cylinder with an open top and a closed bottom.

[0353] The inner diameter of the secondary oil pump (70) is formed to be larger than the outer diameter of the lower portion of the drive shaft (50). For example, the gap between the inner surface of the secondary oil pump (70) and the outer surface of the lower portion of the drive shaft (50) may be 0.1 mm to 0.15 mm.

[0354] A spiral groove (71) may be formed on the inner surface of the secondary oil pump (70). This spiral groove (71) forms a secondary oil path (70a).

[0355] A coupling hole (73) may be formed in the bottom (701) of the secondary oil pump (70). The coupling hole (73) may be formed in the center of the bottom (701) of the secondary oil pump (70).

[0356] The coupling hole (73) is formed so as to be coupled with the coupling projection (63) of the primary oil pump (60). The coupling hole (73) may be formed with a female screw. That is, a female screw corresponding to the male screw (65) of the coupling projection (63) of the primary oil pump (60) may be formed on the inner circumferential surface of the coupling hole (73). Accordingly, the coupling projection (63) of the primary oil pump (60) and the coupling hole (73) of the secondary oil pump (70) may be screw-coupled.

[0357] The secondary oil pump (70) may include at least one oil inlet (72). The at least one oil inlet (72) may be formed on an outer surface of the cylindrical container. The at least one oil inlet (72) may be formed to penetrate the outer surface (702) and the inner surface of the cylindrical container. The at least one oil inlet (72) may be formed on an upper portion of the outer surface (702) of the secondary oil pump (70). The at least one oil inlet (72) may be formed adjacent to an upper end of the secondary oil pump (70).

[0358] At least one oil inlet (72) may be formed to communicate with a secondary oil passage (70a). Accordingly, oil in the oil storage tank (16) may flow into the secondary oil passage (70a) through at least one oil inlet (72).

[0359] In the present embodiment, the secondary oil pump (70) includes two oil inlets (72), but the number of oil inlets (72) is not limited thereto.

[0360] When at least one oil inlet (72) of the secondary oil pump (70) is immersed in oil contained in the oil reservoir (16), the oil in the oil reservoir (16) can flow into the secondary oil path (70a) of the secondary oil pump (70) through the at least one oil inlet (72).

[0361] When the upper part of the secondary oil pump (70) is immersed in the oil of the oil tank (16), the oil of the oil tank (16) can flow into the secondary oil channel (70a) through at least one oil inlet (72) and the upper part of the secondary oil channel (70a) formed at the upper part of the secondary oil pump (70). Therefore, a sufficient amount of oil can flow into the secondary oil channel (70a).

[0362] As another example, the secondary oil pump (70) may not include an oil inlet (72). In this case, the secondary oil pump (70) may be installed so that the upper end of the secondary oil passage (70a) is located below the oil surface of the oil tank (16) (see FIG. 27).

[0363] In the above, the case where the primary oil pump (60) and the secondary oil pump (70) are connected by a screw connection has been described, but the connection of the primary oil pump (60) and the secondary oil pump (70) is not limited to this. Various connection methods can be applied as long as oil does not penetrate into the connection portion of the primary oil pump (60) and the secondary oil pump (70). For example, the primary oil pump (60) and the secondary oil pump (70) can be connected by a press-fit connection.

[0364] Hereinafter, the press-fit coupling of the primary oil pump (60) and the secondary oil pump (70) will be described with reference to FIGS. 32 and 33.

[0365] FIG. 32 is a cross-sectional perspective view showing a state in which a primary oil pump (60) and a secondary oil pump (70) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure are combined.

[0366] Referring to Fig. 32, the primary oil pump (60) and the secondary oil pump (70) are coupled by a press-fit connection. The coupling protrusion (63) of the primary oil pump (60) is formed in a cylindrical shape, and the coupling hole (73) of the secondary oil pump (70) is formed in a circular hole. At this time, the diameter of the coupling protrusion (63) and the inner diameter of the coupling hole (73) are formed to form a force fit. Then, the primary oil pump (60) and the secondary oil pump (70) can be coupled by pressing the coupling protrusion (63) of the primary oil pump (60) into the coupling hole (73) of the secondary oil pump (70).

[0367] In this case, the coupling protrusion (63) of the primary oil pump (60) is pressed into and fixed in the coupling hole (73) of the secondary oil pump (70), so that the secondary oil pump (70) does not rotate with respect to the primary oil pump (60), and oil does not flow into the interior of the secondary oil pump (70) through the coupling hole (73) and the coupling protrusion (63).

[0368] In addition, a through hole (64) is formed at the bottom of the coupling protrusion (63) of the primary oil pump (60). A metal wire (80) fixed to the lower case (12) is inserted into the through hole (64). Therefore, even if the drive shaft (50) rotates, the primary oil pump (60) and the secondary oil pump (70) do not rotate.

[0369] FIG. 33 is a perspective view showing a state in which a primary oil pump (60) and a secondary oil pump (70) of a reciprocating compressor (1) according to one or more embodiments of the present disclosure are combined.

[0370] Referring to Fig. 33, the primary oil pump (60) and the secondary oil pump (70) are coupled by a press-fit joint. The coupling protrusion (63) of the primary oil pump (60) is formed in a square pillar shape, and the coupling hole (73) of the secondary oil pump (70) is formed in a square hole shape. The coupling hole (73) may be formed in a square pipe shape extending downward from the bottom (701) of the secondary oil pump (70).

[0371] At this time, the square pillar-shaped coupling protrusion (63) is formed to be press-fitted into the square coupling hole (73). That is, the coupling protrusion (63) is press-fitted into the coupling hole (73), and is formed so that oil does not penetrate between the coupling protrusion (63) and the coupling hole (73). Then, the coupling protrusion (63) of the primary oil pump (60) can be press-fitted into the coupling hole (73) of the secondary oil pump (70), thereby coupling the primary oil pump (60) and the secondary oil pump (70).

[0372] At this time, since the coupling protrusion (63) of the square pillar of the primary oil pump (60) is pressed into the square coupling hole (73) of the secondary oil pump (70), the secondary oil pump (70) does not rotate with respect to the primary oil pump (60), and oil does not flow into the interior of the secondary oil pump (70) through the coupling hole (73) and the coupling protrusion (63).

[0373] In addition, a through hole (64) is formed at the bottom of the coupling protrusion (63) of the primary oil pump (60). A hole (74) corresponding to the through hole (64) is formed at the side of the square pipe forming the coupling hole (73) of the secondary oil pump (70). A metal wire (80) fixed to the lower case (12) is inserted into the hole (74) of the secondary oil pump (70) and the through hole (64) of the primary oil pump (60). Therefore, even if the drive shaft (50) rotates, the primary oil pump (60) and the secondary oil pump (70) do not rotate.

[0374] As in the embodiments illustrated in FIGS. 19 to 33, when the oil of the oil reservoir (16) flows into the interior of the secondary oil pump (70) through the upper portion of the secondary oil pump (70), compared to the case where the oil of the oil reservoir (16) flows into the interior of the secondary oil pump (70) through the lower portion of the secondary oil pump (70) as in the embodiments illustrated in FIGS. 2 to 18, there is no flow interference between the oil flowing along the secondary oil passage (70a) and the oil flowing along the primary oil passage (61), and the oil flowing into the interior of the secondary oil pump (70) does not flow out through the upper portion of the secondary oil pump (70), so that the oil supply amount can be increased.

[0375] Typically, a refrigerator must rapidly cool its internal space to a target temperature and maintain a constant internal temperature once it reaches that target. At this point, it is desirable to minimize temperature fluctuations. To minimize temperature fluctuations, the reciprocating compressor (1) must operate at a low speed. Furthermore, operating the reciprocating compressor (1) at a low speed reduces power consumption.

[0376] The reciprocating compressor (1) is configured to operate an oil pump by the rotation of a drive shaft (50) to supply oil to internal components requiring lubrication. The amount of oil supplied varies depending on the rotational speed of the drive shaft (50).

[0377] Conventional reciprocating compressors have only one oil pump. Therefore, when the compressor operates at low speeds, the amount of oil supplied to its internal components decreases. This reduced oil supply to internal components increases frictional losses among the components, potentially reducing compressor efficiency. Furthermore, solid-state friction between components can increase vibration and noise in the reciprocating compressor. Consequently, the reliability of the reciprocating compressor can be compromised.

[0378] However, since the reciprocating compressor (1) according to one or more embodiments of the present disclosure supplies oil using dual oil pumps, i.e., a primary oil pump (60) and a secondary oil pump (70), the oil supply amount can be increased compared to a reciprocating compressor according to the prior art that uses a single oil pump.

[0379] Specifically, since the reciprocating compressor according to the present invention uses dual oil pumps, i.e., a primary oil pump (60) and a secondary oil pump (70), the length of the spiral path of the oil pump that raises the oil is longer than the length of the spiral path of the oil pump of the reciprocating compressor according to the prior art that uses only one oil pump, i.e., a primary oil pump, and thus the amount of oil supplied can be increased.

[0380] For example, in the case of a reciprocating compressor (1) according to one or more embodiments of the present disclosure illustrated in FIGS. 34 and 35, since oil moves along the primary oil path (61) and the secondary oil path (70a) of the dual oil pump (F1 and F2), the length of the path is longer than that of a reciprocating compressor according to the prior art in which oil moves only along the primary oil path (e.g., F1). Therefore, the amount of oil supplied can be increased.

[0381] In addition, in the case of the reciprocating compressor (1) according to one or more embodiments of the present disclosure as illustrated in FIGS. 36 and 37, since the oil moves sequentially along the primary oil path (61) and the secondary oil path (70a) of the dual oil pump (F3 and F4), the length of the path is longer than that of the reciprocating compressor according to the prior art in which the oil moves only along the primary oil path (e.g., F4). Therefore, the amount of oil supplied can be increased.

[0382] Accordingly, the reciprocating compressor (1) according to one or more embodiments of the present disclosure can have improved compressor efficiency and reduced vibration and noise. Accordingly, the reliability of the reciprocating compressor (1) according to one or more embodiments of the present disclosure can be improved.

[0383] While the present disclosure has been illustrated and described above with reference to various embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. Case containing a low-pressure tank; A motor including a stator installed inside the case and a rotor rotating with respect to the stator; A drive shaft that rotates integrally with the rotor and includes a cavity formed at the bottom; A primary oil pump inserted into the cavity of the above driving shaft and installed in the case; A secondary oil pump, into which the lower end of the above drive shaft is inserted and which is coupled with the above primary oil pump; A primary oil path formed between the inner surface of the cavity of the above drive shaft and the above primary oil pump; and A secondary oil passage formed between the outer surface of the lower end of the drive shaft and the secondary oil pump around the primary oil passage; A reciprocating compressor, wherein when the drive shaft rotates, the oil contained in the oil tank moves to the upper portion of the cavity of the drive shaft along the primary oil path and the secondary oil path.

2. In paragraph 1, The above drive shaft includes a first oil supply path in a spiral shape formed on the outer surface of the upper part, The above secondary oil pump is a reciprocating compressor formed in the shape of a cylindrical container with a bottom.

3. In paragraph 2, The above drive shaft includes a communicating hole formed adjacent to the upper end of the cavity, The oil contained in the above-mentioned oil tank flows into the secondary oil pump through the lower part of the secondary oil pump, A portion of the oil fed into the secondary oil pump moves upward along the primary oil path, A reciprocating compressor, wherein the remaining oil moves upward along the secondary oil path and enters the cavity through the connecting hole, and moves to the upper part of the cavity together with some of the oil moving along the primary oil path.

4. In paragraph 3, The above secondary oil path is formed as a spiral groove formed on the outer surface of the lower portion of the driving shaft inserted into the above secondary oil pump. A reciprocating compressor, wherein the spiral direction of the spiral groove of the above-mentioned secondary oil path is the same as the spiral direction of the above-mentioned first oil supply path of the spiral shape.

5. In paragraph 3, The above secondary oil path is formed by a spiral groove formed on the inner surface of the above secondary oil pump. A reciprocating compressor, wherein the spiral direction of the spiral groove of the above-mentioned secondary oil path is opposite to the spiral direction of the above-mentioned first oil supply path of the spiral shape.

6. In paragraph 3, A reciprocating compressor, wherein the secondary oil pump comprises a plurality of oil inlets formed at least in one of the bottom and the lower part of the outer surface adjacent to the bottom.

7. In paragraph 3, A reciprocating compressor, wherein the upper end of the secondary oil passage is formed lower than the upper end of the secondary oil pump.

8. In paragraph 7, A reciprocating compressor, wherein the upper end of the secondary oil passage is formed to correspond to the above-described flue hole.

9. In paragraph 3, A reciprocating compressor, wherein the upper part of the secondary oil pump is adjacent to the lower surface of the rotor and is located above the surface of the oil contained in the oil tank.

10. In paragraph 2, The oil contained in the above-mentioned oil tank flows into the secondary oil pump through the upper part of the secondary oil pump, A reciprocating compressor, wherein the oil introduced into the secondary oil pump moves to the lower end of the drive shaft along the secondary oil path and to the upper end of the cavity of the drive shaft along the primary oil path.

11. In Article 10, The above secondary oil path is formed as a spiral groove formed on the outer surface of the lower portion of the driving shaft inserted into the above secondary oil pump. A reciprocating compressor, wherein the spiral direction of the spiral groove of the above-mentioned secondary oil path is opposite to the spiral direction of the above-mentioned first oil supply path of the spiral shape.

12. In paragraph 10, The above secondary oil path is formed by a spiral groove formed on the inner surface of the above secondary oil pump. A reciprocating compressor, wherein the spiral direction of the spiral groove of the above-mentioned secondary oil path is the same as the spiral direction of the above-mentioned first oil supply path of the spiral shape.

13. In paragraph 10, A reciprocating compressor, wherein the secondary oil pump comprises at least one oil inlet formed on an outer surface adjacent to the upper end.

14. In paragraph 10, A reciprocating compressor, wherein the upper end of the secondary oil passage is formed at the upper end of the secondary oil pump.

15. In paragraph 10, A reciprocating compressor, wherein the upper part of the secondary oil pump is adjacent to the lower surface of the rotor and is located below the surface of the oil contained in the oil tank.

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