WO2007043754A1

WO2007043754A1 - Variable capacity compressor

Info

Publication number: WO2007043754A1
Application number: PCT/KR2006/003718
Authority: WO
Inventors: Seong Jun Park
Original assignee: Samsung Gwangju Electronics Co., Ltd.
Priority date: 2005-10-07
Filing date: 2006-09-18
Publication date: 2007-04-19
Also published as: KR20070039193A; CN101278125A; CN101278125B; KR101161124B1

Abstract

A variable capacity compressor for supply an appropriate amount of oil to frictional areas of a rotary shaft(40) or compression unit(20) regardless of a variation in the rotating speed of the rotary shaft . The compressor includes the refrigerant compression unit and a drive unit(30) disposed in a hermetic container(10) having an oil storage space(11), the rotary shaft having an end extending to the oil storage space, an oil flow path(42) formed in the rotary shaft, an oil pickup member(60) secured to the lower end of the rotary shaft to pick up and move the oil into the oil flow path by centrifugal force of the rotary shaft, and pickup blades(71b and 72b) provided in the oil pickup member. The number of the pickup blades that actually perform an oil pumping operation while being immersed in the oil is variable in inverse proportion to the rotating speed of the rotary shaft.

Description

VARIABLE CAPACITY COMPRESSOR

Technical Field

[1] The present invention relates to a variable capacity compressor, and more particularly, to an oil supply structure for the lubrication of frictional areas of a rotary shaft and a compression unit.

Background Art

[2] Recently, variable capacity compressors capable of varying a refrigerant compression capability thereof have been greatly employed in refrigeration cycles of air conditioners or refrigerators, in order to perform an optimum cooling operation satisfying requirements as well as to reduce energy consumption by virtue of a variable cooling capacity thereof.

[3] Considering the general structure of a conventional variable capacity compressor, as shown in FlG. 1, the conventional variable capacity compressor comprises a hermetic container 1 defining an outer appearance of the compressor, a compression unit 2 disposed in the hermetic container 1 and adapted to compress a refrigerant, a drive unit 3 disposed in the hermetic container 1 and adapted to offer power required for the compression of the refrigerant, and a rotary shaft 4 to connect the drive unit 3 and the compression unit 2 to each other in order to transmit the power of the drive unit 3 to the compression unit 2. The variable capacity compressor is adapted to vary a rotating speed of the rotary shaft 4 by regulating a voltage or frequency to be applied to the drive unit 3, thereby achieving a variation in the refrigerant compression capability thereof.

[4] The hermetic container 1 is provided at different locations thereof with a refrigerant suction pipe Ia to introduce a refrigerant from an external station into the hermetic container 1 and a refrigerant discharge pipe Ib to guide the refrigerant compressed in the hermetic container 1 to the outside.

[5] The compression unit 2 includes a cylinder block 2a having a refrigerant compression chamber 2a- 1 defined in a side interior region thereof, a piston 2b installed in the compression chamber 2a- 1 and adapted to perform a rectilinear reciprocating motion, a cylinder head 2c coupled to the cylinder block 2a to hermetically seal the compression chamber 2a- 1, the cylinder head being opened toward the compression chamber 2a- 1 and internally defining a refrigerant suction chamber 2c- 1 and refrigerant discharge chamber 2c-2 separated from each other, and a valve device 2d interposed between the compression chamber 2a- 1 and the cylinder head 2c and adapted to control the flow of the refrigerant being introduced from the refrigerant suction chamber 2c- 1 into the compression chamber 2a- 1 or being discharged from the compression chamber 2a- 1 into the refrigerant discharge chamber 2c-2.

[6] The drive unit 3 includes a stator 3a secured around a lower end of the cylinder block 2a and a rotor 3b located in the stator 3a and adapted to rotate via an electrical interaction with the stator 3a. The rotary shaft 4 is press-fitted in the center of the rotor 3b and adapted to rotate along with the rotor 3b.

[7] The cylinder block 2a is centrally perforated with a through-bore 2a-2 such that an upper portion of the rotary shaft 4 penetrates therethrough. The rotary shaft 4 has an eccentric portion 4a formed at an upper end thereof above the through-bore 2a-2. The eccentric portion 4a of the rotary shaft 4 is connected to the piston 2b through a connecting rod 2e such that an eccentric rotating motion of the eccentric portion 4a is converted into the rectilinear reciprocating motion of the piston 2b. A lower end of the rotary shaft 4 protrudes downward from the rotor 3b to extend to a bottom region of the hermetic container 1.

[8] With the above described configuration, if the rotary shaft 4 rotates along with the rotor 3b by the electrical interaction between the stator 3a and the rotor 3b, the piston 2b, which is connected to the eccentric portion 4a of the rotary shaft 4 through the connecting rod 2e, rectilinearly reciprocates in the compression chamber 2a- 1, thus allowing the refrigerant, which was guided into the hermetic container 1 through the suction pipe Ia, to be delivered into the compression chamber 2a- 1 through the refrigerant suction chamber 2c- 1. After being compressed in the compression chamber 2a- 1, the refrigerant is then discharged to the refrigerant discharge chamber 2c-2 and guided to the discharge pipe Ib, so as to be discharged to the outside of the hermetic container 1. As the above described procedure is repeatedly performed, the compression of the refrigerant can be accomplished. In this case, the refrigerant compression capability of the compressor can be regulated as the rotating speed of the rotary shaft 4 is changed by regulating a voltage and frequency to be applied to the drive unit 3.

[9] Meanwhile, an oil storage space Ic for storing a predetermined amount of oil is defined in the bottom region of the hermetic container 1, and the rotary shaft 4 is internally formed with an oil flow path 4b that delivers the oil of the oil storage space Ic to frictional areas of the rotary shaft 4 or compression unit 2. An oil pickup device is provided at the lower end of the rotary shaft 4 and adapted to communicate the oil storage space Ic with the oil flow path 4b and to pick up and move the oil of the oil storage space Ic toward the oil flow path 4b by a rotating operation of the rotary shaft 4.

[10] The oil pickup device includes an approximately cylindrical oil pickup member 5 having an open upper end to be press-fitted into the lower end of the rotary shaft 4 to thereby be coupled to the rotary shaft 4, and a lower end centrally formed with an oil supply hole 5a, and a pickup plate 6 configured to be press-fitted into the oil pickup member 5.

[11] The pickup plate 6 has a plate-shaped body 6a and a pair of pickup blades 6b located at a lower end of the body 6a. Both the pickup blades 6b are located at opposite sides of the body 6a about a central incision formed at the lower end of the body 6a. The pickup blades 6b are bent oppositely in a rotating direction of the rotary shaft 4.

[12] Accordingly, if the rotary shaft 4 rotates to perform a refrigerant compressing operation, the oil stored in the oil storage space Ic is suctioned upward along the oil pickup member 5 and oil flow path 4b in sequence by a centrifugal force of the rotary shaft 4, thereby being delivered to frictional areas of the rotary shaft 4 or compression unit 2 for the sake of lubrication. In this case, each pickup blade 6b of the pickup plate 6 pumps the oil upward while being immersed below an oil surface level, thereby serving to facilitate an oil pickup operation.

[13] However, in the case of the above described conventional variable capacity compressor, the amount of oil to be supplied to the frictional areas of the rotary shaft 4 or compression unit 2 through the oil pickup device greatly depends on a variation of the centrifugal force that is caused by a difference in the rotating speed of the rotary shaft 4. Therefore, when the rotary shaft 4 rotates at a high speed in order to increase a discharge amount of the refrigerant, excessive amount of oil may be pumped upward, resulting in an excessive increase in electricity consumption required for the pumping operation as well as oil pumping noise. Conversely, when the rotary shaft 4 rotates at a low speed in order to decrease a discharge amount of the refrigerant, insufficient amount of oil may be pumped, making it impossible to achieve efficient lubrication of the rotary shaft 4 or compression unit 2.

Disclosure of Invention

Technical Problem

[14] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a variable capacity compressor which can supply an appropriate amount of oil to frictional areas of a rotary shaft or compression unit regardless of a variation in the rotating speed of the rotary shaft.

Technical Solution

[15] In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a variable capacity compressor comprising: a hermetic container having an oil storage space defined in a bottom region thereof; a compression unit disposed in the hermetic container and adapted to compress a refrigerant; a drive unit disposed in the hermetic container and adapted to offer power required for the compression of the refrigerant; a rotary shaft to connect the drive unit and the compression unit to each other so as to transmit the power of the drive unit to the compression unit and having a lower end extending to the oil storage space, the rotary shaft having a rotating speed that is variable in accordance with a refrigerant compression capacity; an oil flow path formed in the rotary shaft to guide the oil of the oil storage space to factional areas of the compression unit and rotary shaft; a cylindrical oil pickup member secured to the lower end of the rotary shaft and adapted to communicate the oil storage space with the oil flow path in order to pick up and move the oil of the oil storage space into the oil flow path by a centrifugal force of the rotary shaft; and a plurality of pickup blades provided in the oil pickup member to facilitate an oil pumping operation, the number of the pickup blades that actually perform the oil pumping operation while being immersed in the oil of the oil storage space being variable in inverse proportion to the rotating speed of the rotary shaft.

[16] The pickup blades may include a plurality of pickup blade groups that are arranged in multi levels along an axial direction of the rotary shaft.

[17] The pickup blade groups may include a lower first pickup blade group and an upper second pickup blade group.

[18] The variable capacity compressor may further comprise a pickup plate to be press- fitted into the oil pickup member, the pickup blades being formed at the pickup plate, and the pickup plate may comprise: a first pickup plate having the first pickup blade group formed at a lower end thereof; and a second pickup plate having the second pickup blade group formed at a lower end thereof and located above the first pickup plate.

[19] The first and second pickup plates may be detachably coupled to each other.

[20] The first and second pickup plates may have the same shape and size as each other.

[21] Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Advantageous Effects

[22] The present invention provides a variable capacity compressor in which, of a plurality of pickup blades provided in an oil pickup member to assist an oil pumping operation, the number of the pickup blades selected to actually perform the oil pumping operation while being immersed in oil stored in an oil storage space is variable in inverse proportion to the rotating speed of a rotary shaft. This has the effect of allowing an appropriate amount of oil to be supplied to frictional areas of the rotary shaft and compression unit regardless of a variation in the rotating speed of the rotary shaft.

Description of Drawings [23] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[24] FlG. 1 is a sectional view schematically illustrating the general structure of a conventional variable capacity compressor;

[25] FlG. 2 is a sectional view schematically illustrating the general structure of a variable capacity compressor consistent with a preferred embodiment of the present invention;

[26] FlG. 3 is an exploded perspective view of an oil pickup device of FlG. 2, which illustrates an oil pickup member and pickup plate separated from each other;

[27] FlG. 4 is a perspective view of the oil pickup device of FlG. 2, which illustrates an oil pickup member and pickup plate coupled to each other;

[28] FlG. 5 is an enlarged sectional view of the oil pickup device mounted in the variable capacity compressor consistent with the embodiment of the present invention, which illustrates a stopped state of a rotary shaft;

[29] FlG. 6 is an enlarged sectional view of the oil pickup device mounted in the variable capacity compressor consistent with the embodiment of the present invention, which illustrates a high-speed rotating state of a rotary shaft; and

[30] FlG. 7 is an enlarged sectional view of the oil pickup device mounted in the variable capacity compressor consistent with the embodiment of the present invention, which illustrates a low-speed rotating state of a rotary shaft.

Best Mode

[31] Reference will now be made in detail to the embodiment of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiment is described below to explain the present invention by referring to the figures.

[32] Referring to FlG. 2 illustrating a variable capacity compressor consistent with a preferred embodiment of the present invention, the variable capacity compressor comprises a hermetic container 10 defining an outer appearance of the compressor and having an oil storage space 11 in a bottom region thereof, a compression unit 20 disposed in the hermetic container 10 and adapted to compress a refrigerant, a drive unit 30 disposed in the hermetic container 10 and adapted to offer power required for the compression of the refrigerant, and a rotary shaft 40 to connect the drive unit 30 and the compression unit 20 to each other in order to transmit the power of the drive unit 30 to the compression unit 20.

[33] The rotary shaft 40 has a rotating speed that is variable by regulating a voltage or frequency to be applied to the drive unit 30. The variable rotating speed of the rotary shaft 40 consequently enables a variation in the refrigerant compression capability by the compression unit 20. The hermetic container 10 is provided at different locations thereof with a refrigerant suction pipe 12 to guide a refrigerant from an external station into the hermetic container 10 and a refrigerant discharge pipe 13 to guide the refrigerant compressed in the hermetic container 10 to the outside.

[34] The compression unit 20 includes a cylinder block 21 having a refrigerant compression chamber 21a formed in a side interior region thereof, a piston 22 installed in the compression chamber 21a and adapted to perform a rectilinear reciprocating motion, a cylinder head 23 coupled to the cylinder block 21 to hermetically seal the compression chamber 21a, the cylinder head 23 being opened toward the compression chamber 21a and internally defining a refrigerant suction chamber 23a and refrigerant discharge chamber 23b separated from each other, and a valve device 24 interposed between the compression chamber 21a and the cylinder head 23 and adapted to control the flow of the refrigerant being introduced from the refrigerant suction chamber 23a into the compression chamber 21a or being discharged from the compression chamber 21a into the refrigerant discharge chamber 23b.

[35] The drive unit 30 includes a stator 31 secured around a lower end of the cylinder block 21 and a rotor 32 located in the stator 31 and adapted to rotate via an electrical interaction with the stator 31. The rotary shaft 40 is press-fitted in the center of the rotor 32 and adapted to rotate along with the rotor 31.

[36] The cylinder block 21 is centrally perforated with a through-bore 21b such that an upper portion of the rotary shaft 40 penetrates therethrough. The rotary shaft 40 has an eccentric portion 41 formed at an upper end thereof above the through-bore 21b. The eccentric portion 41 of the rotary shaft 40 is connected to the piston 22 through a connecting rod 25 such that an eccentric rotating motion of the eccentric portion 41 is converted into the rectilinear reciprocating motion of the piston 22. A lower end of the rotary shaft 40 protrudes downward from the rotor 32 to extend to the oil storage space 11 of the hermetic container 10.

[37] With the above described configuration, if the rotary shaft 40 rotates along with the rotor 32 by the electrical interaction between the stator 31 and the rotor 32, the piston 22, which is connected to the rotary shaft 4 through the connecting rod 25, rectilinearly reciprocates in the compression chamber 21a, thereby allowing the refrigerant, which was guided into the hermetic container 10 through the suction pipe 12, to be delivered into the compression chamber 21a through the refrigerant suction chamber 23a. After being compressed in the compression chamber 21a, the refrigerant is discharged to the refrigerant discharge chamber 23b and then guided to the discharge pipe 13, so as to be discharged to the outside of the hermetic container 10. As the above described procedure is repeatedly performed, the compression of the refrigerant can be accomplished. In this case, the refrigerant compression capability of the compressor can be regulated as the rotating speed of the rotary shaft 40 is changed by regulating a voltage and frequency to be applied to the drive unit 30.

[38] To supply oil stored in the oil storage space 11 to frictional areas of the rotary shaft

40 and compression unit 20 in the course of compressing the refrigerant for the sake of lubrication, the rotary shaft 40 is internally formed with an oil flow path 42 that guides the oil of the oil storage space 11 to frictional areas of the rotary shaft 40 or compression unit 20. An oil pickup device 50 is provided at the lower end of the rotary shaft 40 and adapted to communicate the oil storage space 11 with the oil flow path 42 and to pick up and move the oil of the oil storage space 11 toward the oil flow path 42 by a rotating operation of the rotary shaft 40.

[39] The oil flow path 42 includes a first oil flow path 42a defined in a lower portion of the rotary shaft 40 below the through-bore 21b, a second oil flow path 42b communicating with the first oil flow path 42a and formed in the upper portion of the rotary shaft 40 inside the through-bore 21b to communicate with an outer peripheral surface of the rotary shaft 40 through holes perforated in the rotary shaft 40 in order to supply the oil into a gap between the through-bore 21b of the cylinder block 21 and the rotary shaft 40, and a third oil flow path 42c communicating with the second oil flow path 42b and formed in the eccentric portion 41 to supply the oil toward the compression unit 20. After passing through the respective oil flow paths 42a, 42b and 42c in this sequence, the oil is returned to the oil storage space 11 so as to be repeatedly supplied into the oil flow path 42.

[40] The oil pickup device 50 includes an approximately cylindrical oil pickup member

60 having an open upper end press-fitted into and coupled to the lower end of the rotary shaft 40 to communicate with the first oil flow path 42a, and a lower end centrally formed with an oil supply hole 61 and adapted to be immersed in the oil stored in the oil storage space 11.

[41] Accordingly, if the rotary shaft 40 rotates to perform a refrigerant compressing operation, the oil stored in the oil storage space 11 is suctioned upward along the oil pickup member 60 and oil flow path 42 in sequence by a centrifugal force of the rotary shaft 40, thereby being delivered to frictional areas of the rotary shaft 40 and compression unit 20 for the sake of lubrication.

[42] The oil pickup device 50 further includes a pickup plate 70 configured to be press- fitted into the oil pickup member 60. In the variable capacity compressor consistent with the present embodiment, the pickup plate 70 has a plurality of pickup blades 71b and 72b configured to pump the oil of the oil storage space 11 upward toward the oil flow path 42. Of the plurality of pickup blades 71b and 72b, the selected number of the pickup blades, which actually perform an oil pumping operation while being immersed in the oil of the oil storage space 11, is variable in inverse proportion to the rotating sp eed of the rotary shaft 40.

[43] The reason why to allow the number of the pickup blades 71b and 72b actually performing the oil pumping operation to be variable in inverse proportion to the rotating speed of the rotary shaft 40 is to supply an appropriate amount of oil to frictional areas of the rotary shaft 40 or compression unit 20 regardless of a variation in the rotating speed of the rotary shaft 40 that is variable in accordance with the refrigerant compression capacity of the compressor.

[44] More specifically, as shown in FIGS. 3 and 4, the pickup plate 70 includes a pair of lower first pickup plate 71 and upper second pickup plate 72. The first pickup plate 71 includes a plate-shaped first body 71a and a pair of first pickup blades 71b formed at a lower end of the first body 71a. Similarly, the second pickup plate 72 includes a plate- shaped second body 72a and a pair of second pickup blades 72b formed at a lower end of the second body 72a.

[45] The lower ends of the first and second bodies 71a and 72a are centrally formed with incisions 71c and 72c, respectively, such that the first pickup blades 71b are located at opposite sides of the incision 71c and bent oppositely in a rotating direction of the rotary shaft 40, and the second pickup blades 72b are located at opposite sides of the incision 72c and bent oppositely in a rotating direction of the rotary shaft 40. The first body 71a is additionally formed at the center of an upper end thereof with an insertion slot 7 Id such that the incision 72c of the second body 72a is engaged downward with the insertion slot 7 Id.

[46] With the above described configuration, if the first and second pickup plates 71 and

72 are press-fitted into the oil pickup member 60 after the second pickup plate 72 is secured to the first pickup plate 71 by inserting the lower end incision 72c of the second body 72a into the upper end insertion slot 7 Id of the first body 71a, the pair of pickup blades 71b define a first group 80 located at a lower region in the oil pickup member 60, and the pair of second pickup blades 72b define a second group 90 located at an upper region in the oil pickup member 60. The resulting first group 80 and second group 90 have a multi-level structure in an axial direction of the rotary shaft 40.

[47] The first and second pickup blades 71b and 72b of the first and second groups 80 and 90 have different heights from each other, and the different positions between the first and second pickup blades 71b and 72b are determined in consideration of the height of an oil surface level in the oil storage space 11 that is variable in accordance with a variation in the rotating speed of the rotary shaft 40.

[48] Specifically, if the rotary shaft 40 rotates at a high speed, the rotary shaft 40 generates a large centrifugal force, thus causing an increased amount of oil to be suctioned upward along the oil pickup member 60 and oil flow path in sequence, and resulting in the lowering of the oil surface level in the oil storage space 11. Conversely, if the rotary shaft 40 rotates at a low speed to reduce the compression capacity, the rotary shaft 40 generates a small centrifugal force, thus causing a reduced amount of oil to be suctioned upward along the oil pickup member 60 and oil flow path in sequence, and resulting in the rising of the oil surface level in the oil storage space 11. In consideration of the height of the oil surface level in accordance with a variation in the rotating speed of the rotary shaft 40, the first pickup blades 71b of the first group 80 are set to be always immersed in the oil of the oil storage space 11. The second pickup blades 72b of the second group 90 are set such that they are immersed in the oil of the oil storage space 11 when the rotary shaft rotates at a low-speed, but are located above the oil surface level of the oil storage space 11 when the rotary shaft 40 rotates at a high-speed.

[49] Now, the oil supply structure of the pickup plate 70 having the above described configuration will be explained based on the high-speed rotation and low-speed rotation of the rotary shaft 40.

[50] First, if the rotary shaft 40, which is in a stopped state, begins to rotate at a high speed in order to achieve a significant increase in the refrigerant compression capability, the centrifugal force of the rotary shaft 40 increases, thus causing an increased amount of oil to be suctioned upward along the oil pickup member 60 and oil flow path 42 in sequence. As a result, the surface level of the oil stored in the oil storage space 11 is lowered significantly as shown in FIG. 6. In such a lowered state of the oil surface level, the second pickup blades 72b of the second group 90 are located above the oil surface level, and only the first pickup blades 71b of the first group 80 are rotated while being immersed in the oil of the oil storage space 11.

[51] Accordingly, the amount of oil pumped by the centrifugal force of the rotary shaft

40 increases, whereas the amount of oil pumped by the pickup plate 70 decreases. Therefore, it is possible to prevent excessive amount of oil from being supplied to the rotary shaft 40 or compression unit 20 even in the high-speed rotation range of the rotary shaft 40.

[52] Also if the rotary shaft 40 rotates at a low speed to reduce the refrigerant compression capacity, the centrifugal force of the rotary shaft 40 decreases, thus causing a reduced amount of oil to be suctioned upward along the oil pickup member 60 and oil flow path 42 in sequence. As a result, the surface level of the oil stored in the oil storage space 11 is raised as shown in FIG. 7. In such a raised state of the oil surface level, all the pickup blades 71b and 72b of the first and second groups 80 and 90 are rotated while being immersed in the oil of the oil storage space 11.

[53] Accordingly, the amount of oil pumped by the centrifugal force of the rotary shaft

40 decreases, whereas the amount of oil pumped by the pickup plate 70 increases. Therefore, it is possible to allow a sufficient amount of oil to be efficiently supplied to frictional areas of the rotary shaft 40 or compression unit 20 even in the low-speed rotation range of the rotary shaft 40.

[54] In the present embodiment, the first pickup plate 71 and second pickup plate 72 are prepared separately to be detachably attached to each other. Accordingly, it can be understood that, if any one of the first and second pickup plates 71 and 72 is damaged, the variable capacity compressor of the present embodiment can achieve easy exchange of the damaged one without requiring the removal of the overall pickup plate 70.

[55] Also, it is noted that the first and second pickup plates 71 and 72 have the same shape and size as each other. Accordingly, the second body 72a of the second pickup plate 72 may be formed with an insertion slot 72d in the same manner as the first pickup plate 71. The same shape and size of both the first and second pickup plates 71 and 72 enable the common use of the first and second pickup plates 71 and 72, and can achieve an improvement in productivity of the variable capacity compressor.

Industrial Applicability

[56] As apparent from the above description, the present invention provides a variable capacity compressor in which, of a plurality of pickup blades provided in an oil pickup member to assist an oil pumping operation, the number of the pickup blades selected to actually perform the oil pumping operation while being immersed in oil stored in an oil storage space is variable in inverse proportion to the rotating speed of a rotary shaft. This has the effect of allowing an appropriate amount of oil to be supplied to frictional areas of the rotary shaft and compression unit regardless of a variation in the rotating speed of the rotary shaft.

[57] Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[1] A variable capacity compressor comprising: a hermetic container having an oil storage space defined in a bottom region thereof; a compression unit disposed in the hermetic container and adapted to compress a refrigerant; a drive unit disposed in the hermetic container and adapted to offer power required for the compression of the refrigerant; a rotary shaft to connect the drive unit and the compression unit to each other so as to transmit the power of the drive unit to the compression unit and having a lower end extending to the oil storage space, the rotary shaft having a rotating speed that is variable in accordance with a refrigerant compression capacity; an oil flow path formed in the rotary shaft to guide the oil of the oil storage space to frictional areas of the compression unit and rotary shaft; a cylindrical oil pickup member secured to the lower end of the rotary shaft and adapted to communicate the oil storage space with the oil flow path in order to pick up and move the oil of the oil storage space into the oil flow path by a centrifugal force of the rotary shaft; and a plurality of pickup blades provided in the oil pickup member to facilitate an oil pumping operation, the number of the pickup blades that actually perform the oil pumping operation while being immersed in the oil of the oil storage space being variable in inverse proportion to the rotating speed of the rotary shaft.

[2] The compressor according to claim 1, wherein the pickup blades include a plurality of pickup blade groups that are arranged in multi levels along an axial direction of the rotary shaft.

[3] The compressor according to claim 2, wherein the pickup blade groups include a lower first pickup blade group and an upper second pickup blade group.

[4] The compressor according to claim 3, further comprising: a pickup plate to be press-fitted into the oil pickup member, the pickup blades being formed at the pickup plate, wherein the pickup plate comprises: a first pickup plate having the first pickup blade group formed at a lower end thereof; and a second pickup plate having the second pickup blade group formed at a lower end thereof and located above the first pickup plate.

[5] The compressor according to claim 4, wherein the first and second pickup plates are detachably coupled to each other.

[6] The compressor according to claim 5, wherein the first and second pickup plates have the same shape and size as each other.