WO2006064987A1

WO2006064987A1 - Oil path for dual capacity compressor

Info

Publication number: WO2006064987A1
Application number: PCT/KR2004/003305
Authority: WO
Inventors: Young Hwan Ko; Jong Bong Kim; Ji Young Bae; Jin Kook Kim
Original assignee: Lg Electronics Inc.
Priority date: 2004-12-15
Filing date: 2004-12-15
Publication date: 2006-06-22

Abstract

Disclosed is a lubricating mechanism for a compressor with two compression capacities. The lubricating mechanism includes a first path (110) extending within a driving shaft (13) rotating clockwise and counterclockwise and being configured to pump an oil, and a second path (120) formed at any one of bearings (24, 25) sealing a cylinder (21) and supporting the driving shaft (13) rotatably, wherein the second path (120) is configured to allow the pumped oil to uniformly flow between the bearings (24, 25)and the driving shaft(13).

Description

OIL PATH FOR DUAL CAPACITY COMPRESSOR

Technical Field

The present invention relates to a dual capacity compressor, and more particularly to a mechanism for supplying a lubricant to driving parts in the dual capacity compressor.

Background Art

In various apparatuses requiring a compression of a working fluid, particularly, in home appliances such as refrigerators employing a refrigerating cycle, a load on the appliance actually varies at all times, and thus requires a variation of a compression capacity of the compressor according to a variation of the load in order to improve operation efficiency. To meet such capacity variation requirement of the compressor, there has been various technical attempts, such as a variable rotation speed compressor, a multi- cylinder compressor, and the like. However, these technologies have many problems in a practical usage because of a cost, and/or an increased size of the compressor. Accordingly, instead of such technologies, a rotary compressor having dual compression capacity by employing a simple mechanical structure has been developed recently.

In such dual capacity compressor, as mechanical elements such as a motor, a driving shaft and the like move in a high speed, a proper lubrication is fairly important. Furthermore, such elements are under a severe operational environment due to additional movements necessary for the variation of the compression capacity. Therefore, an appropriate lubricating mechanism should be developed together with a variable capacity mechanism.

Disclosure of Invention

Accordingly, the present invention is contemplated to substantially obviate one or more problems due to limitations and disadvantages of the related art. An object of the present invention is to provide a lubricating mechanism adapted for a capacity variation mechanism.

To achieve such object, the present invention provides an oil path for a dual capacity compressor which comprises a first path extending within a driving shaft rotating clockwise and counterclockwise and being configured to pump an oil, and a second path formed at any one of bearings sealing a cylinder and supporting the driving shaft rotatably, wherein the second path is configured to allow the pumped oil to uniformly flow between the bearings and the driving shaft.

The second path is preferably configured to allow the oil to flow between the driving shaft and the bearings in both of clockwise and counterclockwise rotations of the

> driving shaft. Specifically, the second path comprises a single straight groove allowing the oil to flow therein regardless of rotational directions of the driving shaft. Alternatively, the second path comprises first and second helical grooves each configured to allow the oil to flow therein in corresponding rotation of the driving shaft. The first and second helical grooves extend in opposite directions and do not intersect each other.

In addition, the second path is preferably positioned where an eccentricity of the driving shaft is small..The second path is actually spaced apart from the vane in clockwise or counterclockwise direction. In this case, the single straight groove is preferably spaced apart from the vane by a range of 170°-210° in clockwise or counterclockwise direction, and more preferably spaced apart from the vane by 190° in clockwise or counterclockwise direction. It is desirable that the first and second helical grooves are spaced apart from the vane respectively by 130°-190° and 190°-250° in clockwise or counterclockwise direction.

The second path is formed at an upper bearing installed at an upper portion of the cylinder, at least. The second path is formed on an inner circumferential surface of the bearing, and continuously extends from an upper end to a lower end of the bearing.

Further, the second path is provided with the oil from the first path, and more specifically, communicates with the first path. For such a purpose, the first path includes at least one hole formed at the driving shaft and connecting the first path with the second path.

The first path is configured to disperse the oil toward driving parts of the compressor. Preferably, the first path continuously extends from a lower end to an upper end of the driving shaft, and passes through the driving shaft in an axial direction of the driving shaft.

The oil path further comprises an auxiliary path formed at any one of journals in the driving shaft. The auxiliary path is formed on an outer circumferential surface of the journal. The auxiliary path is preferably configured to allow the oil to flow between the driving shaft and the bearings in both of clockwise and counterclockwise rotations of the driving shaft. Specifically, the auxiliary path comprises a single straight groove allowing the oil to flow therein regardless of rotational directions of the driving shaft. Alternatively, the auxiliary path comprises first and second helical grooves each configured to allow the oil to flow therein in corresponding rotation of the driving shaft.

^■ By the invention described above, driving parts in the dual capacity compressor are appropriately lubricated while operating for the two different capacities.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Brief Description of Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated as a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: FIG. 1 is a partial longitudinal sectional view of a dual capacity compressor to which an oil path according to the present invention is applied;

FIG. 2 is a cross-sectional view of a cylinder taken along a line I-I of FIG. 1 ; - A -

FIG. 3 is a front view showing the oil path of the dual capacity compressor according to the present invention;

FIG. 4A is a sectional view taken along a line II-II of FIG. 3 and showing a first embodiment of a second path; FIG. 4B is a partial sectional view showing an inner circumferential surface of a bearing which includes the first embodiment of the second path;

FIG. 4C is a graph showing an optimal setting angle of the first embodiment of the second path;

FIG. 5A is a sectional view taken along the line II-II of FIG. 3 and showing a second embodiment of the second path;

FIG. 5B is a partial sectional view showing the inner circumferential surface of the bearing which includes the second embodiment of the second path;

FIG. 5C is a graph showing the optimal setting angle of the second embodiment of the second path; and FIGS. 6A and 6B are partial front views each showing an auxiliary path.

Best Mode for Carrying Out the Invention

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts.

FIG. 1 is a partial longitudinal sectional view of a dual capacity compressor to which an oil path according to the present invention is applied, and FIG. 2 is a cross- sectional view of a cylinder of taken along a line I-I of FIG. 1. As shown in FIG. 1, a rotary compressor of the present invention includes a case 1 and a power generating unit 10, a compressing unit 20, and a capacity varying unit 30 which are positioned in the case 1. Referring to FIG. 1, the power generating unit 10 is positioned on the upper portion of the rotary compressor and the compressing unit 20 is positioned on the lower portion of the rotary compressor. However, their positions may be changed if necessary. An upper cap 3 and a lower cap 5 are installed on the upper portion and the lower portion of the case 1 respectively to define a sealed inner space. A suction pipe 7 for sucking working fluid is installed on a side of the case 1 and connected to an accumulator 8 for separating lubricant from refrigerant. A discharge pipe 9 for discharging the compressed fluid is installed on the center of the upper cap 3. A predetermined amount of the lubricant "O" is filled in the lower cap 5 so as to lubricate and cool members that are moving fictionally. An end of a driving shaft 13 is dipped in the lubricant O.

The power generating unit 10 includes a stator 11 fixed in the case 1, a rotor 12 rotatably supported in the stator 11, and the driving shaft 13 inserted forcibly into the rotor 12. The rotor 12 is rotated by electromagnetic force, and the driving shaft 13 delivers the rotation force of the rotor to the compressing unit 20. To supply external power to the stator 20, a terminal 4 is installed in the upper cap 3. The rotor 12 can rotate reversibly. That is, the rotor 12 can rotate in both of clockwise and counterclockwise directions, and thus the driving shaft 13 can rotate in the clockwise and counterclockwise directions together with such rotor 12.

The compressing unit 20 includes a cylinder 21 fixed to the case 1, a roller 22 disposed in the cylinder 21 (see FIG. 2), and upper and lower bearings 24 and 25 respectively installed on upper and lower portions of the cylinder 21.

The cylinder 21 has a predetermined inner volume and strength enough to endure the pressure of the fluid. As shown in FIG. 2, the cylinder 21 accommodates an eccentric portion 13a formed on the driving shaft 13 in the inner volume thereof. The eccentric portion 13a is a kind of an eccentric cam and has a center spaced by a predetermined distance from its rotation center. The cylinder 21 has a groove 21a extending by a predetermined depth from its inner circumference. A vane 23 to be described below is installed on the groove 21a. The groove 21a is long enough to accommodate the vane 23 completely.

The roller 22 is a ring member that has an outer diameter less than the inner diameter of the cylinder 21. As shown in FIG. 2, the roller 22 contacts the inner circumference of the cylinder 21 and rotatably coupled with the eccentric portion 13 a. Accordingly, the roller 22 performs rolling motion on the inner circumference of the cylinder 21 while spinning on the outer circumference of the eccentric portion 13a when the driving shaft 13 rotates. The roller 22 revolves spaced apart by a predetermined distance from the rotation center due to the eccentric portion 13a while performing the rolling motion. Since the outer circumference of the roller 22 always contacts the inner circumference due to the eccentric portion 13 a, the outer circumference of the roller 22 and the inner circumference of the cylinder form a separate fluid chamber 29 in the inner volume of the cylinder. The fluid chamber 29 is used to suck and compress the fluid in the rotary compressor. The vane 23 is installed in the groove 21a of the cylinder 21 as described above.

An elastic member 23a is installed in the groove 21a to elastically support the vane 23, and thus causes the vane 23 to continuously contact the roller 22. In other words, the elastic member 23a has one end- fixed to the cylinder 21 and the other end coupled with the vane 23, and pushes the vane 23 toward the roller 22. Accordingly, the vane 23 divides the fluid chamber 29 into two separate spaces 29a and 29b as shown in FIG. 2. While the driving shaft 13 rotate or the roller 22 revolves, the volumes of the spaces 29a and 29b change complementarily. In other words, if the roller 22 rotates clockwise, the space 29a gets smaller but the other space 29b gets larger. However, the total volume of the spaces 29a and 29b is constant and approximately same as that of the predetermined fluid chamber 29. One of the spaces 29a and 29b works as a suction chamber for sucking the fluid and the other one works as a compression chamber for compressing the fluid relatively when the driving shaft 13 rotates in one direction (clockwise or counterclockwise). Accordingly, as described above, a compression chamber of the spaces 29a and 29b gets smaller to compress the previously sucked fluid and a suction chamber expands to suck the new fluid relatively according to the rotation of the roller 22. If the rotation direction of the roller 22 is reversed, the functions of the spaces 29a and 29b are exchanged. More specifically, if the roller 22 revolves counterclockwise, the right space 29b of the roller 22 becomes the compression chamber, but if the roller 22 revolves clockwise, the left space 29a of the roller 22 becomes the compression chamber.

The upper bearing 24 and the lower bearing 25 are, as shown in FIG. 1, installed on the upper and lower portions of the cylinder 21 respectively, and rotatably support the driving shaft 12. The cylinder 21, the upper bearing 24 and the lower bearing 25 are coupled with one another to seal the cylinder inner volume, especially the fluid chamber 29 using coupling members such as bolts and nuts.

The capacity varying unit 30 comprises, though not shown in detail, suction and discharge ports for allowing the working fluid to be suck into and to be discharged from the cylinder 21 in both rotational directions of the driving shaft 13 and a "valve assembly for controlling the suction ports. The discharge ports are formed at the upper bearing 24 to be adjacent to the vane 23, and correspond to the clockwise and counterclockwise rotations of the driving shaft 13, respectively. Likewise, the suction ports are formed at the lower bearing 25 to correspond to the clockwise and counterclockwise rotations of the driving shaft 13 respectively, but are spaced apart from each other. Further, the valve assembly is disposed between the lower bearing 25 and the cylinder 21, and opens one of the suction ports selectively according to the rotational direction of the driving shaft. Since the compression in the rotary compressor is achieved only between the opened suction port and the discharge port corresponding to such suction port as well known in the art, the sizes of the spaces involved in the compression are different from each other according to the rotational direction of the driving shaft, due to the suction ports spaced from each other. Consequently, two compression capacity different from each other are obtained by the capacity varying unit 30 described above. Such capacity varying unit 30 is disclosed in International Application No. PCT/KR2004/000998 filed by the identical applicant. However, the disclosed capacity varying unit is only an example, and any modification that varies the capacity depending on the rotation direction could be employed as the capacity varying unit for the compressor of the present invention.

Meanwhile, during the operation the compressor, mechanical elements such as the motor 11, 12, the driving shaft 13, and the roller 22 are in a high-speed rotation. Especially, as the driving shaft 13 alternately repeats the clockwise and counterclockwise rotations, this driving shaft 13 is exposed to a severer operational condition in the compressor of the present invention. Accordingly, a proper lubrication and a lubricating mechanism for such lubrication are fairly important for a stable operation of the compressor. The present invention provides an oil path as such lubricating mechanism configured to supply oil, i.e. lubricant "O" to driving elements in the compressor, and this oil path will be specifically described as follows, referring relevant drawings. FIG. 3 is a front view showing the oil path of the dual capacity compressor according to the present invention. FIGS. 4A-4C are drawings each illustrating a first embodiment of a second path included in the oil path, and FIGS. 5A-5C are drawings each illustrating a second embodiment of the second path.

As shown, the lubricating mechanism, i.e. the oil path 100 is formed along the driving shaft 13 and the bearings 24, 25. Journals 13b, 13c of the driving shaft 13 are surrounded by the upper and lower bearings 24, 25 respectively, and substantially form radial bearings supporting load normal to a center axis of the driving shaft. Additionally, collars 13d, 13e form together with the bearings 24, 25 thrust bearings supporting load in axial direction. The oil path 100 mainly comprises a shaft path 110 (hereinafter, referred to as "a first path") formed within the driving shaft 13.

More specifically, the first path 110 extends from a lower end of the driving shaft 13 to an upper end, and thus substantially passes through the driving shaft in a length direction thereof. In addition, at a lower end of the first path 110, an oil pump 111 is mounted. This oil pump 110 is a sort of a centrifugal pump, and includes an oil pickup Ilia and a propeller 111b inserted into the oil pickup Ilia. The oil pump 111 is dipped in the lubricant, i.e. the oil "O" in a bottom portion of the compressor (see FIG. 1), and thus the oil can flows in the first path 110 through the oil pump 111. Then, the oil is pumped along the first path 110 and is dispersed at the upper end of the driving shaft 13 in order to be supplied to corresponding driving parts. Additionally, the first path 110 further includes holes 112a, 112b formed at an upper portion and a lower portion of the eccentric portion 13a respectively to communicate with the first path 110. The oil is first supplied into the cylinder 21 though the holes 112a, 112b so as to lubricate the roller 22 and the eccentric portion 13 a. The holes 112a, 112b also allows the oil to be supplied to the upper and lower bearings 24, 25 and the driving shaft 13, accurately the journals 13b, 13c.

However, as the journals 13b, 13c and the bearings 24, 25 form large frictional surfaces as illustrated, the oil could not reach ends of the frictional surfaces only with a small amount of supply through the holes 112a, 112b. That is, the oil could not be spread all over the frictional surfaces, and could not entirely form oil films thereon for a prevention of abrasion. To solve such a problem, the oil path 100 in the present invention has a bearing path 120 (hereinafter, referred to as "a second path") formed at any one of the bearings 24, 25 as shown in FIG. 3, FIGS. 4A-4B, and FIGS. 5A-5B. The second path 120 is substantially formed as a groove formed on an inner circumferential surface in any one of the bearings. The second path 120 communicates with the driving shaft 13, more accurately any one of the holes 112a, 112b adjacent thereto in order to be provided with the oil by the first path 110. In addition, the second path 120 preferably extends continuously between an upper end and a lower end of the inner circumferential surface. Therefore, the oil is supplied to the second path 120 by any one of the holes 112a, 112b, and then flows between both ends of the inner circumferential surface along the second path 120. Namely, due to the second path 120, the oil path 100 is configured to allow the oil to uniformly flow between the bearings 24, 25 and the driving shaft 13. The oil then spreads equally on the frictional surfaces, and forms the oil films entirely in order to effectively prevent the abrasion. It is desirable that such second path 120 is formed at the upper bearing 24 at least. This is because in the lower bearing, the oil can flows downward to some extent by gravity from the holes 112b. However, it is more desirable for suitable lubrication that the second paths 120 are formed at both of the upper and lower bearings 24, 25 respectively.

As described above, since the driving shaft 13 rotates in clockwise and counterclockwise directions, the second path 120 should be able to allow the oil to flow therein in both rotational directions of the compressor. The second path. 120 might be formed as a helical groove. This helical groove expands a substantial flow passage and enables a sufficient oil supply. However, the helical groove can allow the oil to flow therein in any one direction of the rotations of the driving shaft 13 due to its geometric characteristic. More specifically, the helical groove can allow the oil to flow and ascend therein only when it extends in a direction opposite to the rotational direction of the driving shaft 13. Accordingly, in a first embodiment, the second path 120 comprises a single straight groove as shown in FIGS. 4 A and 4B. The straight groove is not affected by the geometrical characteristic contrary to the helical groove, and can allow the oil to flow therein by centrifugal force generated by the driving shaft 13 regardless of the rotational direction of the driving shaft. Alternatively, as a second embodiment, the second path 120 comprises first and second helical grooves 120a, 120b as shown in FIGS. 5 A and 5B. More specifically, the helical groove can allow the oil to flow therein only in any one of the rotational directions of the driving shaft 13 as explain above. Therefore, two helical grooves corresponding to the rotational direction respectively are applied to the present invention, and these grooves extend in opposite directions (the clockwise and counterclockwise directions). Also, if the first and second helical grooves 120a, 120b intersect each other on the inner circumferential surfaces of the bearings 24, 25, the oil flowing in one helical groove leaks into the other helical groove. As such a leakage causes the bearings 24, 25 and the journals 13b, 13c not to be entirely lubricated, it is important for an optimal lubrication that the helical grooves 120a, 120b do not intersect each other.

Meanwhile, referring to FIGS. 4 A and 5 A, clearances C with predetermined sizes are formed between the bearings 24, 25 and the driving shaft 13 (more accurately, the journals 13b, 13c), and the oil fills such clearances C using the second paths 120 to form the oil films therein. The driving shaft 13 is subject to pressure from the compressed working fluid during the operation of the compressor, and thus rotates eccentric from centers O of the bearings 24, 25. In addition, as the second paths 120 damage the inner circumferential surfaces of the bearings continuously along their length directions, the clearances C are increased around the second paths 120 and the sufficient oil films are not formed around the second paths 120 due to the increased clearances C. Accordingly, if the second paths 120 are positioned where an eccentricity of the driving shaft 13 is greatly generated , the driving shaft 13 may be in contact with the inner circumferential surfaces of the bearings 24, 25. hi this case, the abrasion between the bearings 24, 25 and the driving shaft 13 may occur, and simultaneously, nose may be made during the operation of the compressor. Also, the power loss of the driving shat 13 may occur due to the excessive abrasion. Therefore, it is preferable for the second paths 120 to be positioned where the eccentricity of the driving shaft 13 is small. More specifically, the second paths 120 are formed at portions of the inner circumferential surfaces in the bearings 24, 25, which confront positions where the eccentricity of the driving shaft 13 is small.

In the present invention, optimal positions of the second paths 120 were determined by experiments, and FIGS. 4C and 5C show experimental results considered for the optimal positions in the first and second embodiments of the second path 120, respectively.

As illustrated, FIGS. 4C and 5C are graphs each showing change of an eccentricity ratio to an angle. First, the angle is set to be 0° at the vane 23 positioned beneath and above the bearings 24, 25, and is also set to increase in the direction of rotation in which the maximum compression capacity is generated. The compressor was set to generate the maximum compression capacity in the counterclockwise rotation in the experiment, and thus the angle was set to increase in the counterclockwise direction as show. The eccentricity ratio is defined as a ratio of an eccentric distance (i.e. a distance from the bearing center O to a center of the driving shaft) to the clearance C. This eccentricity ratio is a dimensionless index showing how much the driving shaft 13 is close to the inner circumferential surfaces of the bearings 24, 25. As the clearance C is constant, the great eccentricity ratio means that the driving shaft has a great amount of the eccentricity and is close to the inner circumferential surfaces of the bearings 24, 25. The eccentricity ratios were also measured with regard to both of the maximum and minimum compression capacities. The eccentricity ratio in the maximum capacity was measured in the counterclockwise rotation of the driving shaft 13 as described above, and the eccentricity ration in the minimum capacity was measured in the clockwise rotation. Due to differences in various operational conditions as well as in compression capacities according to the rotational directions, the eccentricity ratios in the maximum and minimum capacities have different phases. As a result of the experiment, such eccentricity ratios were not greatly changed and rather showed almost identical tendencies, with regard to various specifications of the compressors subject to the experiment. First, as the working fluid is maximally compressed near the vane 23, both eccentricity ratios of the maximum and minimum capacities have relatively great values at 0° (360°), i.e. at the vane 23, as shown in FIGS. 4C and 5C. In addition, if the second path 120 is positioned above or beneath the vane 23, the working fluid having the maximum pressure near the vane 23 may leak into such second path 120. In view of these conditions, it is preferable that the second paths 120 according to the first and second embodiments are basically spaced apart from the vane 23 in the clock or counterclockwise direction with reference to the center O. More specifically, in the first embodiment of the second path 120, the eccentricity ratios in the maximum and rninimum capacities have relatively small values in a range of 170° - 210°, as shown in FIG. 4C. Accordingly, the single straight groove according to the first embodiment is preferably spaced apart from the vane 23 by an angle A of 170° - 210° in the counterclockwise direction. In addition, the compressor of the present invention could be designed to have the maximum compression capacity in the clockwise rotation (i.e. the minimum compression capacity in the counterclockwise rotation). Even in this case, it would be appreciated that the same result as FIG. 4C is obtained, when the angle is set to increase in the clockwise direction in which the maximum capacity is obtained, to be opposite to FIG 4 A. Therefore, the single straight groove could be spaced apart from the vane 23 by the angle of 170° - 210° in the counterclockwise or clockwise direction. Additionally, the eccentric ratios in the maximum and minimum capacities have the same small value at 190°. That is, chances to be contact with shaft are minimized in both of the clockwise and counterclockwise rotations. Accordingly, it is most preferable for the angle A to be 190°. In the second embodiment, as the second path 120 comprises the first and second helical grooves 12Oa₅ 120b, it is important for these grooves 120a, 120b to be disposed respectively within angle ranges having relatively small eccentricity ratios so as not to interfere with each other. Referring to FIG. 5C, the eccentricity ratios have relatively small values in the ranges of angle in the vicinity of 190°. Accordingly, as illustrated, the first and second helical grooves 120a, 120b are spaced apart from the vane 23 by a first angle Bl and a second angle B2 respectively in the clockwise or counterclockwise directions, and these angles Bl, B2 have ranges of 130° - 190° and 190° - 250°, respectively. Further, the second path 120 has appropriate width w and depth d in order to allow the sufficient amount of the oil to flow therein as well as to reduce the damage on the inner circumferential surfaces of the bearings interrupting a formation of the oil films. These width w and depth d are preferably 3.8mm and 1.67mm respectively, although they are slightly varied according to the specifications of the compressors. Further, to allow the oil to flow more sufficiently between the bearings 24, 25 and the driving shaft 13, the oil path 100 additionally includes an auxiliary path 130 as shown in FIGS. 4 A, 5 A and FIGS. 6A-6B. This auxiliary path 130 comprises grooves formed along the journals 13b, 13c, and preferably extends over entire lengths of the journals 13b, 13c. Likewise, it is desirable that the auxiliary path 130 is configured to allow the oil to flow therein in all the rotational directions of the driving shaft 13. Accordingly, the auxiliary path 130 comprises a single straight groove as shown in FIGS. 4 A and 6 A, or two helical grooves 130a, 130b as shown in FIGS. 5 A and 6B.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Industrial Applicability In the present invention, uniform oil films are formed between a driving shaft and bearings by a lubricating mechanism as explained above. Accordingly, an abrasion of the driving shaft is effectively prevented under the severe operational environment. Further, such lubricating mechanism allows the oil to flow therein in all the rotational directions of the driving shaft and is positioned where an eccentricity of the driving shaft is small. Therefore, the lubrication for preventing the abrasion becomes more stable and effective.

Claims

1. An oil path for a dual capacity compressor comprising: a first path extending within a driving shaft rotating clockwise and counterclockwise, and being configured to pump an oil; and a second path formed at any one of bearings sealing a cylinder and supporting the driving shaft rotatably, the second path configured to allow the pumped oil to uniformly flow between the bearings and the driving shaft.

2. The oil path of claim 1 , wherein the second path is configured to allow the oil to flow between the driving shaft and the bearings in both of clockwise and counterclockwise rotations of the driving shaft.

3. The oil path of claim 1, wherein the second path comprises a single straight groove allowing the oil to flow therein regardless of rotational directions of the driving shaft.

4. The oil path of claim 1, wherein the second path comprises first and second helical grooves each configured to allow the oil to flow therein in corresponding rotation of the driving shaft.

5. The oil path of claim 4, wherein the first and second helical grooves extend in opposite directions.

6. The oil path of claim 4, wherein the first and second helical grooves do not intersect each other.

7. The oil path of claim 1, wherein the second path is positioned where an eccentricity of the driving shaft is small.

8. The oil path of claim 1, wherein the second path is positioned where the driving shaft does not closely approach.

9. The oil path of claim 1, wherein the second path is spaced apart from the vane in clockwise or counterclockwise direction.

10. The oil path of claim 3, wherein the single straight groove is spaced apart from the vane by a range of 170°-210° in clockwise or counterclockwise direction.

11. The oil path of claim 10, wherein the single straight groove is spaced apart from the vane by 190° in clockwise or counterclockwise direction.

12. The oil path of claim 4, wherein the first and second helical grooves are spaced apart from the vane respectively by 130°-190° and 190"-250° in clockwise or counterclockwise direction.

13. The oil path of claim 1 , wherein a width of the second path is 3.8mm.

14. The oil path of claim 1, wherein a depth of the second path is 1.67mm.

15. The oil path of claim 1, wherein the second path is formed at an upper bearing installed at an upper portion of the cylinder at least.

16. The oil path of claim I₅ wherein the second path is formed on an inner circumferential surface of the bearing.

17. The oil path of claim 1, wherein the second path continuously extends from an upper end to a lower end of the bearing.

18. The oil path of claim 1, wherein the second path is provided with the oil from the first path.

19. The oil path of claim 1, wherein the second path communicates with the first path.

20. The oil path of claim 1, wherein the first path includes at least one hole formed at the driving shaft and connecting the first path with the second path.

21. The oil path of claim I₅ wherein the first path is configured to disperse the oil toward driving parts of the compressor.

22. The oil path of claim I₅ wherein the first path continuously extends from a lower end to an upper end of the driving shaft.

23. The oil path of claim 1, wherein the first path passes through the driving shaft in an axial direction of the driving shaft.

24. The oil path of claim 1, further comprising an auxiliary path formed at any one of journals in the driving shaft.

25. The oil path of claim 24, wherein the auxiliary path is formed on an outer circumferential surface of the journal.

26. The oil path of claim 24, wherein the auxiliary path is configured to allow the oil to flow between the driving shaft and the bearings in both of clockwise and counterclockwise rotations of the driving shaft.

27. The oil path of claim 24, wherein the auxiliary path comprises a single straight groove allowing the oil to flow therein regardless of rotational directions of the driving shaft.

28. The oil path of claim 24, wherein the auxiliary path comprises first and second helical grooves each configured to allow the oil to flow therein in corresponding rotation of the driving shaft.