Background Art In general, compressors are machines that are supplied power from a power generator such as electric motor, turbine or the like and apply compressive work to a working fluid, such as air or refrigerant to elevate the pressure of the working fluid.

Such compressors are widely used in a variety of applications, from electric home appliances such as air conditioners, refrigerators and the like to industrial plants.

The compressors are classified into two types according to their compressing methods: a positive displacement compressor, and a dynamic compressor (a turbo compressor).

The positive displacement compressor is widely used in industry fields and configured to increase pressure by reducing its volume. The positive displacement compressors can be further classified into a reciprocating compressor and a rotary compressor.

The reciprocating compressor is configured to compress the working fluid using a piston that linearly reciprocates in a cylinder. The reciprocating compressor has an advantage of providing high compression efficiency with a simple structure.

However, the reciprocation compressor has a limitation in increasing its rotational speed due to the inertia of the piston and a disadvantage in that a considerable vibration occurs due to the inertial force.

The rotary compressor is configured to compress working fluid using a roller eccentrically revolving along an inner circumference of the cylinder, and has an advantage of obtaining high compression efficiency at a low speed compared with the reciprocating compressor, thereby reducing noise and vibration.

However, in spite of the aforementioned advantages, the rotary compressor has a structural limitation not allowing the roller to revolve in both directions. In other words, the conventional rotary compressor is provided with only a single

suction port and a single discharge port, which communicate with the cylinder. The roller performs its rolling motion from an inlet side to an outlet side along the inner circumference of the cylinder to compress the working fluid, such as refrigerant.

Accordingly, when the roller performs its rolling motion in a reverse direction, i. e., from the outlet side to the inlet side, it is impossible to compress the working fluid.

Furthermore, the aforementioned structure of the conventional compressor makes it impossible to vary its compression capacity. Recently, there are appearing compressors in which the compression capacity is variably changed so as to correspond to a variety of operational conditions of air conditions. However, the conventional rotary compressor has a limitation in its application since it has only a single compression capacity.

Disclosure of Invention Accordingly, the present invention is directed to a rotary compressor that substantially obviates one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a rotary compressor enabling compression stroke while rotating clockwise or counterclockwise.

Another object of the present invention is to provide a rotary compressor capable of varying the compression capacity.

A further object of the present invention is to provide a rotary compressor that can prevent lubricant oil from accumulating on a fluid suction line.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and according to the purpose of the invention, as embodied and broadly described herein, there is provided a rotary compressor. The rotary compressor includes: a compression chamber provided with a suction port formed on an upper portion of the compression chamber, and discharge

ports formed on a lower portion of the compression chamber, for discharging compressed fluid when pressure is increased above a predetermined level; a rolling member axially biased from a center of the compression chamber, for compressing the compression chamber while rolling in first and second directions along an inner wall of the compression chamber and selectively revolving in the first direction or the second direction; and a partitioning member disposed between the discharge ports, for partitioning the compression chamber into two independent spaces by continuously contacting the rolling member.

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 in and constitute 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 sectional view of a rotary compressor according to a first embodiment of the present invention; FIG. 2 is an exploded perspective view illustrating a compression part of a rotary compressor depicted in FIG. 1; FIG. 3 is a sectional view of a compression part of a rotary compressor depicted in FIG. 1 ; FIGs. 4A to 4D are sectional views illustrating an operation of a rotary compressor according to a first embodiment of the present invention when a roller revolves counterclockwise; FIGs. 5A to 5D are sectional views illustrating an operation of a rotary compressor according to a first embodiment of the present invention when a roller revolves clockwise; FIG. 6 is a sectional view illustrating a modified example of a compression part depicted in FIG. 3;

FIG. 7 is a sectional view of a rotary compressor according to a second embodiment of the present invention; FIG. 8 is a sectional view of a compression part of a rotary compressor depicted in FIG. 7; FIG. 9 is a sectional view of a cylinder depicted in FIG 7; FIGs. lOA and lOB are plane views illustrating rotational angle control means depicted in FIG. 7; FIGs. 11A to 11C are sectional views illustrating an operation of a rotary compressor according to a second embodiment of the present invention when a roller revolves counterclockwise; and FIGs. 12A to 12C are sectional views illustrating an operation of a rotary compressor according to a second embodiment of the present invention when a roller revolves clockwise.

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 like parts.

FIG. 1 is a sectional view of a rotary compressor according to a first embodiment of the present invention, FIG 2 is an exploded perspective view illustrating a compression part of a rotary compressor depicted in FIG 1, and FIG. 3 is a sectional view of a compression part of a rotary compressor depicted in FIG 1. An embodiment of a rotary compressor according to the invention will be described with reference to the accompanying drawings.

As shown in FIG 1, the inventive rotary compressor includes a case 1, a power generating part 10 disposed in the case 1, and a compressing part 20 disposed in the case 1. In the drawing, although the power generating part 10 is disposed above the compressing part 20, they may be reversibly disposed if required. Upper and lower ends of the case 1 are respectively closed by upper and lower caps 3 and 5, to define a sealed inner space of the case 1. The case 1 is connected to an accumulator for separating lubricant from refrigerant by an suction pipe 7. Disposed

through a center of the upper cap 3 is an outlet tube 9 for discharging hydraulic fluid from the case. Filling the lower cap 5 is a predetermined amount of lubricant O.

The power generating part 10 includes a stator 11, a rotor 12 rotatably disposed in the stator 11, and a driving shaft 13 fitted in the rotor 12. The rotor 12 rotates by electro-magnetic force for lubricating and cooling frictionally-operated parts of the compressor. To supply external electric power to the stator 20, a terminal 4 is installed on the upper cap 3.

The compressing part includes a cylinder 21 fixedly mounted on the case 1, a roller 22 disposed in the cylinder 21, and upper and lower bearings 24 and 25 disposed above and below the cylinder, respectively. The compressing part 20 will be described in more detail with reference FIGs. 2 to 4 hereinafter.

The cylinder provides a predetermined inner volume, having sufficient rigidity to withstand hydraulic pressure. Disposed in the inner volume of the cylinder is an eccentric portion 13a formed on a driving shaft 13. The eccentric portion 13a is a type of cam having a predetermined eccentric radius from the rotational axis of the driving shaft 13. The cylinder 21 is provided at its inner circumference with a groove 21b of a predetermined depth. A vane 23 is elastically installed in the groove 21b. That is, the groove 21b is designed having a sufficient depth that can completely receive the vane.

The roller 22 is a ring member having an outer diameter of less than an inner diameter of the cylinder 21. As shown in FIG. 4, the roller 22 is rotatably coupled on the eccentric portion 13a, contacting the inner circumference of the cylinder 21.

Accordingly, when the driving shaft 13 rotates, the roller 22 rotates around its axis and rolls along the circumference of the cylinder. At this point, the eccentric portion 13a allows the roller 22 to further move around the rotational axis of the cylinder.

As the outer circumference of the roller 22 continuously contacts the inner circumference of the cylinder 21 by the electric portion 13a, an additional fluid chamber 29 is defined between the outer circumference of the roller 22 and the inner circumference of the cylinder 21, within the cylinder. The fluid chamber 29 is used for suction and compression of the fluid.

As described above, the vane 23 is disposed in the groove 21b of the cylinder 21, while being biased by an elastic member 23a disposed in the groove 21b such that it can continuously contact the roller 22. That is, the elastic member 23a has a first end fixed on the cylinder 21 and a second end fixed on the vane 23, thereby biasing the vane 23 toward the roller 22. Accordingly, the vane 23, as shown in FIGs. 3 and 4, divides the fluid chamber 29 into two independent spaces 29a and 29b. The volumes of the spaces 29a and 29b are complementarily varied according to the rotation of the driving shaft 13 (i. e. , the revolution of the roller). That is, as the roller 22 rotates clockwise, the space 29a is gradually reduced while the space 29b is gradually increased. Namely, the sum of the volume of the spaces 29a and 29b is uniformly maintained to be substantially identical to the volume of the fluid chamber 29. The spaces 29a and 29b alternately function as either one of the fluid suction chamber and the fluid compression chamber, according to the rotational direction of the driving shaft. Therefore, according to the rotation of the roller 22, the volume of one of the spaces 29a or 29b is gradually reduced to compress the fluid fed thereto so as to function as the fluid compression chamber, and the volume of the other of the spaces 29a and 29b is gradually increased to newly suck the fluid so as to function as the fluid suction chamber. When the rotational direction of the roller 22 is reversed, the functions of the spaces 29a and 29b are also reversed.

As shown in FIG. 2, the upper and lower bearings 24 and 25 are respectively disposed above and below the cylinder 21 to rotatably support the driving shaft 13 using sleeves 24c and 25c provided with through holes 24b and 25b, respectively.

Describing in more detail, the upper and lower bearings 24 and 25 and the cylinder 21 are provided with plural coupling holes 24a, 25a, and 21a that face each other.

Coupling members such as bolts and nuts are used to tightly couple the cylinder 21 and the upper and lower bearings 24 and 25 to each other, thereby defining the fluid chamber 29 in the cylinder 21 in an airtight manner. The upper bearing 24 is provided with a fluid suction passage 24d communicating with the suction pipe 7, and a suction port 26 for communicating the fluid chamber 29 with the fluid suction passage 24d. The suction chamber 26 guides the fluid to be compressed to the fluid chamber 29. The fluid suction passage 24d, as shown in FIGs. 2 and 3, is defined by

a hole penetrating the upper bearing 24. However, the present invention is not limited to this. For example, the fluid suction passage may be formed as a tube connecting the suction port 26 to the suction pipe 7.

The fluid suction passage 24d may directly connect the suction pipe 7 to the suction port 26, or more preferably, as shown in FIGs. 2 and 3, it may indirectly connect the suction pipe 7 to the suction port 26 through a plenum 40.

The plenum 40 is provided with an inner storage space 41 for temporarily accommodating fluid fed through the suction pipe 7, and is disposed covering a portion of the upper bearing 24 as shown in FIG. 3. The plenum 40 directly communicates with the suction port 26 to feed the fluid thereto. The plenum 40 may be directly fixed on the upper bearing 24 by welding, or it may be coupled with the cylinder 21 and the upper and lower bearings 24 and 25 by coupling members.

Accordingly, the plenum 40 is provided with a hole 42 for the sleeve 24c.

Preferably, the plenum 40 is designed having a volume that is 100-400% as large as that of the fluid chamber 29, to stably supply the fluid. The plenum 40 is connected to the suction pipe 7 to store the fluid. That is, the plenum 40 is connected to the suction pipe 7 through the fluid suction passage 24d. In this case, the fluid suction passage 24d may be formed penetrating the upper bearing 24.

When the plenum 40 is installed as described above, the fluid suction passage 24d communicates with the fluid storing space 41 defined between the plenum 40 and the top of the upper bearing 24, and the fluid chamber 29 communicates with the plenum 40 by the suction port 26. Here, the suction port 26 is formed to vertically penetrate the bearing 24 to connect the fluid chamber 29 to the plenum 40 by the shortest path. As the plenum 40 is designed to continuously store a predetermined amount of fluid, a pressure variation of the fluid being fed can be temporarily increased. As a result, the fluid can be stably supplied to the suction port 26.

Therefore, the plenum 40 can either replace or assist the function of the accumulator 8.

The lower bearing 25 is provided with discharge ports 27a and 27b, communicating with the fluid chamber 29 to discharge the compressed fluid out of the fluid chamber 29. The discharge ports 27a and 27b may be directly

communicated with the fluid chamber 29, or be indirectly communicated with the same through a fluid passage (not shown) formed on the lower bearing 25. An opening/closing operation of the discharge ports 27a and 27b is controlled by discharge valves 27c and 27d, installed on the lower bearing 25. The discharge valves 27c and 27d selectively open the discharge ports 27a and 27b only when the pressure of the fluid chamber 29 is increased to above a predetermined level. To this end, each of the discharge valves 27c and 27d is designed having a first end fixed in the vicinity of the respective discharge ports 27a and 27b, and a second end formed on a flat spring. As shown in FIG. 3, installed on upper portions of the discharge valves 27c and 27d are retainers 27e and 27f for limiting the deformation of the valves 27c and 27. The retainer 27e and 27f are disposed contacting the discharge valve 27c and 27d to control the opening extents of the discharge valves 27c and 27d.

If there are no retainers 27e and 27f, the discharge valves 27c and 27d may be deformed due to the high pressure, whereby the reliability of the discharge valves 27c and 27d may be deteriorated.

Disposed under the lower bearing 25 is a muffler 30 for reducing noise generated when the compressed fluid is discharged. A predetermined space is defined between the lower bearing 25 and the muffler 30. The compressed fluid discharged out of the fluid chamber 29 through the discharge ports 27a and 27b is expanded within the space defined between the lower bearing 25 and the muffler 30, thereby reducing the noise in a method identical to the conventional expansion muffler.

The fluid directed to the muffler 30 through the discharge ports 27a and 27b of the lower bearing 25 is fed to an upper space of the cylinder 21, as shown in FIG. 3.

A fluid exhaust passage 50 is defined by through holes 51,52, and 53 that are sequentially formed penetrating the lower bearing 25, the cylinder 21, and the upper bearing 24, respectively. By way of the fluid exhaust passage 50, as shown in FIG. 1, the fluid compressed in the compressing part 20 is discharged out of the compressor through the outlet tube 9 via the power generating part 10.

Alternatively, as shown in FIG. 6, the fluid exhaust passage 50 can be defined by an exhaust pipe 54 having a first end communicating with the muffler 30.

Although not shown in the drawing, a second end of the exhaust pipe 54 is designed communicating with an upper space of the compressing part 10. Furthermore, instead of providing the muffler 30, the exhaust pipe 54 may be designed directly communicating with the discharge ports 27a and 27b.

Meanwhile, the revolution direction of the roller 22 and the location of the suction port 26 are very important factors for determining the compression capacity in a preferred embodiment of the present invention. Their relationship will be described in more detail hereinafter.

FIG. 4a shows the cylinder in a displaced position when the roller of the rotary compressor according to a preferred embodiment of the present invention revolves counterclockwise.

As shown in the drawing, the fluid chamber 29 is divided into the two spaces 29a and 29b by the vane 23 and the roller 22. The discharge ports 27a and 27b are respectively located on each side of the vane 23 to continuously compress fluid regardless of the revolving direction of the roller 22. That is, regardless of the revolving direction of the roller, at least one of the discharge ports 27a and 27b is opened between the suction port 26 and the vane 23. At this point, it is preferable that a distance between the vane 23 and the discharge port 27a is identical to that between the vane 23 and the discharge port 27b.

When the roller 22 rotates, one of the two spaces 29a and 29b becomes a fluid discharge portion for discharging compressed fluid. The fluid discharge portion is then determined according to the revolving direction of the roller 22. That is, when the roller 22 revolves counterclockwise, as shown in FIG. 4a, the right space 29b with respect to the roller 22 becomes the fluid discharge space, and when revolves clockwise, as shown in FIG 5a, the left space 29a becomes the discharge space.

Meanwhile, the compression capacity of the compressor is determined by volumes of the discharge portions 29a and 29b. The volumes of the discharge portions 29a and 29b are determined by spaces enclosed by the cylinder 21 and the roller 22 from the suction port 26 to the vane 23. Accordingly, the compression capacity is determined by the location of the suction port 26.

For example, when the suction port 26 is located on a imaginary line extending from a longitudinal axis of the vane 23, that is, when the suction port 26 is located spaced apart from the vane 23 by an angle of about 180°, the volume of the discharge portion 29a becomes identical to that of the discharge portion 29b.

Therefore, an identical capacity can be obtained from the compressor regardless of the revolving direction of the roller 22.

However, when the suction port 26 is located on one side of the imaginary line extending from the longitudinal axis of the vane 23, the discharge portions 29a and 29b of the compression chamber 29 become different in their volumes. That is, as shown in FIG. 4a, the compression chamber 29 is divided in the left and right spaces 29a and 29b. The left space 29a is defined by a counterclockwise angle between the vane 23 and the suction port 26, and the right space 29b is defined by a clockwise angle between the vane 23 and the suction port 26, the counterclockwise angle being less than the clockwise angle. At this point, the spaces 29a and 29b become low and high capacity discharge portions 29b and 29a according to the revolving direction of the roller 22. This shows that the rotary compressor of the present invention has a dual-capacity.

The location of the suction port 26 is then determined by a compression ratio between the high and low capacity outer portions 29b and 29a. For example, the present invention proposes a clockwise angle of about 180-300° between the vane 23 and the suction port 26. When the clockwise angle between the vane 23 and the suction port 26 is 180°, the compression ratio between the spaces 29b and 29a becomes 50: 50. When the clockwise angle between the vane 23 and the suction port 26 is about 270°, the compression ratio between the spaces 29b and 29a is about 75: 25,.

The operation of the rotary compressor of the present invention will now be described in more detail.

FIGs. 4A to 4D show consecutive operating steps of the rotary compressor when the roller revolves counterclockwise. FIG. 4A shows an initial fluid suction step, FIG. 4B shows a fluid compression/discharge step, FIG. 4C shows a discharge

completion step, and FIG. 4D shows a vacuum area formed in the compression chamber.

As the crankshaft 13 rotates, the roller 22 rotates and revolves counterclockwise along the inner circumference of the cylinder 21. During this process, the suction port 26 is opened so that fluid is sucked into the fluid chamber 29 through the suction port 26. The fluid is then directed to the high capacity discharge portion 29b by the roller 22 as shown in FIG. 4A.

As the roller 22 further revolves, the volume of the high capacity discharge portion 29b is reduced to compress the fluid. During this process, the vane 23 maintains the seal of the high capacity discharge portion 29b while elastically reciprocating by the spring 23a and the roller 22, at the same time of which fluid is continuously fed into the high capacity discharge portion 29b through the suction port 26.

After that, when pressure of the high capacity discharge portion 29b is increased above a predetermined level, the discharge valve 27d of the high capacity discharge portion 29b is opened. Accordingly, the fluid in the high capacity discharge portion 29b starts being discharged to the muffler 30 through the discharge port 27b, as shown in FIG. 4B.

Then, when the roller further revolves, the fluid in the high capacity discharge portion 29b is completely discharged to the muffler 30 through the discharge port 27b, after which the discharge valve 27d closes the discharge port 27b using its self-elastic force, as shown in FIG. 4C.

After that, as the roller 22 further revolves, the fluid is further discharged to the muffler 22 through the above described suction, compression, and discharge steps.

In the course of the above described operation, a vacuum area V is formed on a portion of the fluid chamber 29. That is, as shown in FIG. 4d, after the discharge step, as the roller further revolves, the fluid in the fluid chamber 29 is forcedly directed toward the high capacity discharge portion 29b by the roller 22. However, an area through which the roller 22 has passed, i. e. , a left space defined by the vane 23 and the roller 22, becomes the vacuum area V The area is maintained as the vacuum area V until the suction port 26 is opened by the revolution of the roller 22.

Accordingly, the vacuum area V is periodically formed each time the roller 22 makes one revolution.

FIGs. 5A to 5D shows consecutive operating steps of the rotary compressor when the roller revolves clockwise. FIG. 5A shows an initial fluid suction step, FIG.

5B shows a fluid compression/discharge step, FIG 5C shows a discharge completion step, and FIG. 5D shows a vacuum area formed in the compression chamber.

As the crankshaft 13 rotates, the roller 22 rotates and revolves clockwise along the inner circumference of the cylinder 21. During this process, the suction port 26 is opened so that fluid is sucked into the fluid chamber 29 through the suction port 26. At this point, the fluid is directed to the low capacity discharge portion 29a by the roller 22, as shown in FIG. 5A.

As the roller 22 further revolves, the volume of the low capacity discharge portion 29a is reduced to compress the fluid. During this process, the vane 23 maintains the seal of the low capacity discharge portion 29a while elastically reciprocating by the spring 23a and the roller 22, at the same time of which fluid is continuously fed into the high capacity discharge portion 29b through the suction port 26.

After that, when pressure of the high capacity discharge portion 29a is increased above a predetermined level, the discharge valve 27c of the low capacity discharge portion 29b is opened. Accordingly, the fluid in the low capacity discharge portion 29b starts being discharged to the muffler 30 through the discharge port 27a, as shown in FIG. 5B.

Then, when the roller 22 further revolves, the fluid in the low capacity discharge portion 29a is completely discharged to the muffler 30 through the discharge port 27a, after which the discharge valve 27c closes the discharge port 27a using its self-elastic force, as shown in FIG. 5C.

After that, as the roller 22 further revolves clockwise, the fluid is further discharged to the muffler 22 through the above-described suction, compression, and discharge steps.

Likewise, in the course of the above described operation, a vacuum area V is formed on a portion of the fluid chamber 29. That is, as shown in FIG. 5D, after the

discharge step, as the roller further revolves, the fluid in the fluid chamber 29 is forcedly directed toward the low capacity discharge portion 29a by the roller 22.

However, an area through which the roller 22 has passed, i. e. , a right space 29b defined by the vane 23 and the roller 22, becomes the vacuum area V The area is maintained as the vacuum area V until the suction port 26 is opened by the revolution of the roller 22. In this case, the vacuum area V formed when the roller revolves clockwise is greater than the vacuum area V formed when the roller revolves counterclockwise.

Referring again to FIG. 1, the compressed gas in the muffler 140 is discharged into the case 1 through the discharge port 141, and is then further directed to a desired destination through a space between the rotor 30 and the stator 20 or a space between the stator 20 and the case 1.

The rotary compressor of the present invention has an advantage of varying the compression capacity while rotating in forward and reverse directions. However, the inventive rotary compressor may have some of the following problems.

The periodically incurred vacuum area V causes a sudden pressure variation.

That is, when the suction port 26 is opened as the roller 22 revolves, a substantial pressure difference is incurred between the vacuum area V and the suction port 26.

Such a pressure difference causes several negative results. First, the pressure difference deteriorates the compression efficiency of the compressor. Second, it may act as a substantial load on the crankshaft 13, thereby causing a loss of power.

Third, it may cause periodic noise to be incurred around the suction port 26.

To avoid the above negative results, there is a need to eliminate the vacuum area V. To eliminate the vacuum area V, a structure for supplying fluid, preferably which is not compressed, to the vacuum area V is required. Therefore, the present invention provides a bypass structure for supplying fluid from the suction port 26 to the vacuum area V.

A bypass line of the bypass structure is a one-way fluid passage allowing only uncompressed fluid to be directed to the fluid chamber. That is, the one-way fluid passage prevents the compressed fluid from flowing in a reverse direction. The bypass structure has a valve member that is automatically opened and closed by

pressure difference. That is, since the bypass line is the one-way fluid passage, an open/close control valve member is further required. The bypass structure may have two one-way fluid passages. As described above, the fluid chamber is divided into the high and low capacity discharge portions 29b and 29a, each having a different vacuum area V according to the revolving direction of the roller 22. Accordingly, in order to eliminate the vacuum area regardless of the revolving direction of the roller 22, one of the two one-way fluid passages is connected to the high capacity discharge portion 29b, and the other is connected to the low capacity discharge portion 29a.

The bypass structure may have a storing member for storing uncompressed fluid.

As the bypass structure has the fluid passage connecting the suction port 26 to the fluid chamber, uncompressed fluid can be continuously fed to the vacuum area V An embodiment illustrating the above described bypass structure will be described hereinafter with reference to FIG. 6, which shows a modified example of the compression part depicted in FIG. 3. For descriptive convenience, the suction port 26 provided on the upper bearing 26 is not illustrated in FIG. 6.

Referring to FIG. 6, the bypass lines 28a and 28b are provided on the upper bearing 24 to connect the plenum 40 to the fluid chamber 29. That is, the bypass lines 28a and 28b are designed to communicate the plenum 40 with the spaces 29a and 29b, respectively. The bypass lines 28a and 28b may be designed corresponding to, for example, the discharge ports 27a and 27b provided on the lower bearing 25.

Respectively installed on the bypass lines 28a and 28b are bypass valves 28c and 28d allowing uncompressed fluid to be directed into the fluid chamber 29. Each of the bypass valves 28c and 28d is formed of a flat spring having a first end supported on a groove of each of the bypass lines 28c and 28d, and a second end that is free. Accordingly, the bypass valves 28c and 28d are designed to open/close the bypass lines 28a and 28b by their self-elastic force. At this point, the bypass valves 28c and 28d open the bypass lines 28a and 28b only when the pressure difference between the bypass lines and the fluid chamber is increased above a predetermined level.

Meanwhile, installed in the grooves of the bypass lines are retainers 28e and 28f for ensuring the stable operation of the bypass valves 28c and 28f. That is, the

retainers 28e and 28f are disposed contacting the bypass valves 28c and 28d, respectively, to control an opening amount of the bypass valves 28c and 28d.

Alternatively, the bypass lines may be defined by holes passing through the upper bearing 24 and the cylinder 21 to communicate the fluid suction passage 24d or the plenum 40 with the fluid chamber 29. In this case, fluid in the suction passage 24d or the plenum 40 is directed into the fluid chamber 29 through the holes, performing the identical function to that of the embodiment depicted in FIG 6.

A process for eliminating the vacuum area by the bypass structure of the rotary compressor will be described hereinafter.

When the roller rotates counterclockwise, fluid in the high capacity discharge portion 29b is discharged through the discharge port 27b. When the discharge of the fluid is completed as shown in FIG. 4c, the vacuum area is formed between the roller 22 and the vane 23 as shown in FIG. 4d, as a result of which a pressure difference between the vacuum area V and the plenum 40 is increased to open the bypass valve 28c. When the bypass valve 28c is opened, uncompressed fluid in the plenum 40 is fed to the space 29a of the fluid chamber 29 through the bypass line 28a, thereby eliminating the vacuum area.

When the roller 22 rotates counterclockwise, the uncompressed fluid in the plenum 40 is directed into the space 29b of the fluid chamber 29 through the bypass line 28b.

FIGs. 7 to 9 show a rotary compressor according to a second embodiment of the present invention. This embodiment is identical to the first embodiment except for the compression part.

A compressor of this embodiment includes a case, a power generating part, and a compression part. Since the case and the power generating part are identical to those of the first embodiment, a detailed description thereof will be omitted herein.

Referring first to FIG. 7, a compression part of this embodiment includes a cylinder 21 fixed on the case, a roller 22 disposed in the cylinder 21, and upper and lower bearings 24 and 25 respectively disposed above and below the cylinder 21. The compression part further includes a valve assembly 60 disposed between the lower

bearing 24 and the cylinder 21, a plenum 40 disposed on top of the upper bearing 24, and a muffler 30 disposed at the bottom of the lower bearing 25.

The upper bearing 24 is provided with suction ports 41a, 41b, and 41c that communicate with the fluid chamber 29 to direct fluid to be compressed into the fluid chamber 29. The suction ports 41a, 41b, and 41c further communicate with the plenum 40. The lower bearing 25 is provided with discharge ports 27a and 27b communicating with the fluid chamber 29 to discharge fluid compressed in the fluid chamber 29.

The suction and discharge ports 41a, 41b, 41c, 27a, 27b are very important elements in determining the compression capacity of the rotary compressor of this embodiment, and their detailed description will be made with reference to FIGs. 9 to lOB. FIG. 9 show the cylinder 21 assembled with the upper bearing 24. To clearly show the suction ports 41a, 41b, and 41c, the valve assembly 60 is omitted in this drawing. In addition, the discharge ports 27a and 27b are shown with imaginary lines in FIG. 9 for descriptive convenience.

As the two discharge ports 27a and 27b are provided, the compressed fluid is always discharged out of the fluid chamber 29 regardless of the revolving direction of the roller 22. That is, a single discharge port is provided with respect to one revolving direction of the roller 22. Compression chambers defined by the spaces 29a and 29b are reduced in volume as the roller 22 approaches the vane 23. Accordingly, in order to maximize the discharge amount of the compressed fluid, it is preferable that the discharge ports 27a and 27b are adjacently disposed on both side of the vane 23, facing each other. That is, the discharge ports 27a and 27b are respectively disposed on left and right sides of the vane 23. Preferably, the discharge ports 27a and 27b are disposed as close as possible to the vane 23.

The suction ports 41a and 41c are properly located such that fluid can be compressed between the discharge ports 27a and 27b and the roller 22. Actually, the compression of the fluid is performed from one of the suction ports to one of the discharge ports, which is located on the revolving path of the roller 22. That is, a relative position between the suction port and the corresponding discharge port determines the compression capacity. Therefore, as two different suction ports 41a

and 41c are used, two different compression capacities can be obtained according to the revolving direction of the roller. Therefore, the present invention provides first and second suction ports 41a and 41c respectively corresponding to the discharge ports 27a and 27b. A clockwise angle from the vane 23 to the first suction port 41a is different from a counterclockwise angle from the vane 23 to the second suction port 41c, so that two different compression capacities can be obtained according to the revolving direction of the roller 22.

Preferably, the clockwise angle from the vane 23 to the first suction port 41a is greater than the counterclockwise angle from the vane 23 to the second suction port 41c. Accordingly, when the roller 22 revolves counterclockwise, the compression is realized from the first suction port 41 a to the second discharge port 27b located over the vane 23, as a result of which the compression is realized through the overall volume of the chamber 29, thereby providing the maximum compression capacity.

That is, the fluid is compressed by as much as the overall volume of the chamber 29.

As shown in FIG. 9, the first suction port 41 a is spaced apart from the vane 23 by a predetermined angle 81 clockwise or counterclockwise (by 10°counterclockwise in the drawing). At this angle 01, The overall volume of the fluid chamber 29 can be used for the compression without any conflict with the vane 23.

The second suction port 41c is spaced apart from the vane 23 by a clockwise angle 02 such that the compression is realized from the second suction port 41c to the first discharge port 27a when the roller 22 revolves clockwise. The clockwise angle 02 is determined such that the compression is realized using only a portion of the chamber 29. That is, the compression capacity obtained when the roller revolves clockwise is less than that obtained when the roller revolves counterclockwise.

Preferably, the second suction port 41c is spaced apart from the vane 41 by 90-180° clockwise or counterclockwise. It is further preferable that the second suction port 41c is disposed opposing the first suction port 41a so that they do not conflict with each other.

The suction ports 41a and 41c can be formed as circular holes as shown in FIG 9, or as rectangular slots having a predetermined curvature as shown in FIGs. 7, 10a,

and lOb. The curvature of the slots minimizes conflict with other parts, particularly with the roller 22.

Meanwhile, to obtain a desired compression capacity, only one suction port should exist with respect to each revolving direction of the roller 22. That is, if there are two suction ports on the revolving path of the roller, the compression cannot be realized, because when the first suction port 41a is opened, the second suction port 41c must be closed and vice-versa. To achieve this, the compressor of the present invention further includes the valve assembly 60 for selectively opening/closing the suction ports 41 a and 41c according to the revolving direction of the roller 22.

As shown in FIGs. 7, 10A, and 10B, the valve assembly 60 includes first and second valves 61 and 65 installed between the cylinder 21 and the upper bearing 24, to be adjacent to the suction ports 41a, 41b, and 41c.

The first valve is, as shown in FIG. 7, formed of a disk member contacting the eccentric portion 13a of the driving shaft 13. Therefore, when the driving shaft 13 rotates, i. e. , when the roller revolves, the first valve 61 rotates in an identical direction to that of the driving shaft 13. Preferably, the first valve 61 has a diameter greater than the inner diameter of the cylinder 21 so that the outer circumference of the first valve 61 can be stably and rotatably supported by the cylinder 21.

The first valve 61 is provided with first and second openings 61 and 61c respectively communicating with the first and second suction ports 41a and 41c according to a revolving direction of the roller 22. The first valve 61 is further provided with a through hole 61a through which the driving shaft 13 passes.

Describing in more detail, the first opening 61a communicates with the first suction port 41a by the rotation of the first valve 61 when the roller 22 rotates in a first direction, while the second suction port 41c is closed by the body portion of the first valve 61. The second opening 61c communicates with the second suction port 41c when the roller 22 rotates in a second direction, while the first suction port 41a is closed by the body portion of the first valve 61. The first and second openings 61a and 61c are formed in a circular shape as shown in FIG. 9, or formed as rectangular slots having a predetermined curvature as shown in FIG. 7. The rectangular slot provides an enlarged opening size, allowing the fluid to be smoothly supplied.

When the openings 61a and 61c are disposed adjacent to the center of the first valve 61, they may conflict with the roller 22 and the eccentric portion 13a. In addition, since the openings 61a and 61c communicate with a gap between the roller 22 and the eccentric portion 13a, the fluid may leak along the driving shaft 13. Therefore, it is preferable that the openings 61a and 61c are disposed adjacent to the outer circumference of the first valve 61.

Alternatively, by adjusting the rotational angle of the first valve 61, the first opening 61a opens the first and second suction ports 41a and 41c according to the rotational direction. That is, when the driving shaft 13 rotates in a first direction, the first valve 61 closes the second suction port 41c and the first opening 61a communicates with the second suction port 41c. Control of the suction ports using such a single opening 61 a simplifies the structure of the first valve 61.

Meanwhile, the second valve 65 is fixed between the cylinder 21 and the upper bearing 24 to guide the rotational motion of the first valve 61. The second valve 65 is formed of a ring member having a seat 65b for rotatably receiving the first valve 61. The second valve 65 is provided with a coupling hole 65a so that it can be coupled with the cylinder 21 and the upper and lower bearings 24 and 25 by a coupling member. For the prevention of the fluid leakage and the stable support, a thickness of the second valve 65 is preferably identical to that of the first valve 61.

Furthermore, as the first valve is partly supported by the cylinder 21, the thickness of the first valve 61 may be slightly less than that of the second valve 65 to define a gap for the smooth rotation of the second valve.

Referring again to FIG. 9, as the roller 22 revolves from the vane 23 to the second suction port 41c, no fluid is sucked or discharged between the vane 23 and the roller 22. Accordingly, the area V is under vacuum. The vacuum area V causes an increase of noise and power loss of the driving shaft 13. Therefore, a third suction port 14b is further provided on the bearing to eliminate the vacuum area V. The third suction port 41b is located between the second suction port 41c and the vane 23 such that uncompressed fluid can be fed to a space between the roller 22 and the vane 23, thereby preventing the vacuum from being applied before the roller 22 passes over the second suction port 41c. It is preferable that the third suction port 41b is

located in the vicinity of the vane 23 so that the vacuum can be quickly released.

However, since the third suction port 41b is operated in a different rotational direction from that of the first suction port 27a, it is preferable that the third suction port 41b is disposed opposing the first suction port 41a. More preferably, the third suction port 41b is spaced apart from the vane by an angle 03 of 10° in a clockwise or counterclockwise direction. Likewise, the first and second suction ports 41a and 41c and the third suction port 41b may be formed in a circular or a curved rectangular shape.

The third suction port 41b is synchronized with the second suction port 41c.

That is, when the roller 22 revolves, the suction ports 41b and 41c should be simultaneously opened. Accordingly, the first valve 61 may be further provided with a third opening communicating with the third suction port 41b when the second suction port 41c is opened. In the present invention, the third opening may be independently formed. However, since the first and third suction ports 41a and 41b are disposed adjacent to each other, as shown in FIGs. lOa and lOb, it is preferable that both the first and third suction ports 41a and 41b are opened by the first opening 61 a according to the rotational direction by increasing the rotational angle of the first valve 61.

To obtain a desired compression capacity, the suction ports 41a, 41b, and 41c should be precisely opened. The precise opening of the suction ports 41a, 41b, and 41c can be realized by controlling the rotational angle of the first valve.

Accordingly, the valve assembly 60 may preferably be further provided with means for controlling the rotational angle of the first valve 61. The rotational angle control means will be described more in detail with reference to FIGs. 10A and lOB.

As shown in the drawings, the rotational angle control means includes a projection 62 projected on the first valve 61 in a radial direction, and a receiving groove 66 formed on the second valve 65 to movably receive the projection 62.

Since the groove 66 is formed on the second valve 65, it is not exposed to the inner volume of the cylinder 21, thereby preventing dead volume that is not used for compression from occurring in the cylinder.

Alternatively, the control means is comprised of a projection extending in a radial direction from the second valve 65 and a groove formed on the first valve 61 to receive the projection. That is, the control means can be realized by a variety of modified examples.

By way of the control means, when the driving shaft 13 rotates counterclockwise, as shown in FIG. 10a, the projection 62 is caught on one end of the groove 66. As a result, the first opening 61a communicates with the first suction port 41a, while the second and third suction ports 41c and 41b are closed. When the driving shaft 13 rotates clockwise, as shown in FIG. lOb, the projection 62 is caught by the groove 66 such that the first and second openings 61a and 61c open the third and second suction ports 41b and 41c and the first suction port 41a is closed by the first valve 61.

The operation of the rotary compressor of the second embodiment of the present invention will be described in more detail hereinafter.

FIGs. 11A to 11C show the consecutive operation steps of the rotary compressor of this embodiment when the roller rotates counterclockwise.

When the driving shaft 13 rotates counterclockwise, as shown in FIG 11 A, the first suction port 41 a communicates with the first opening 61 a, while the second and third suction ports 41c and 41b are closed. The operation of the suction ports in the counterclockwise rotation is already described with reference to FIG. 10A, the detailed description of which will be omitted herein.

In a state where the first suction port 41 a is opened, the roller 22 rolls along the inner circumference of the cylinder 21 by the rotational motion of the driving shaft 13. As the roller 22 continuously rolls, that is, continuously revolves, as shown in FIG. 11B, the space 29b is reduced to compress the fluid. In the course of this process, the vane 23 elastically moves by the elastic member 23a to divide the fluid chamber 29 in the two sealed spaces 29a and 29b. At this point, fresh fluid is fed to the space 29a through the first suction port 41a and is compressed in the next stroke.

When fluid pressure in the space 29b is increased above a predetermined level, the second discharge valve 27b is opened, as a result of which, as shown in FIG. 11 C,

the fluid in the space 29b is discharged through the second discharge port 27b. As the roller 22 continuously revolves, the fluid in the space 29b is completely discharged through the second discharge port 27b. After the discharge of the fluid is completed, the second discharge valve 27d closes the second discharge port 27b by using its self-elastic force.

After one stroke is completed as described above, the roller 22 continuously revolves counterclockwise to repeatedly discharge fluid through the process of the stroke. In the counterclockwise stroke, the roller 22 compresses the fluid while revolving from the first suction port 41a to the second discharge port 27b. As described above, since the first suction port 41 a and the second discharge port 27b are adjacently disposed on the both sides of the vane 23 while opposing each other, the fluid is compressed by the variation of the volume of the fluid chamber 29 in the counterclockwise stroke, thereby obtaining the maximum amount of compression capacity.

FIGs. 12A to 12C show the consecutive operation steps of the rotary compressor of this embodiment when the roller rotates clockwise.

When the driving shaft 13 rotates clockwise, as shown in FIG. 12A, the first suction port 41a is closed, while the second and third suction ports 41c and 41b respectively communicate with the second and first openings 61c and 61a. When the first valve 61 is additionally provided with the third opening (not shown), the third suction port 41b communicates with the third opening. The operation of the suction ports in the counterclockwise rotation is already described with reference to FIG. 10B, the detailed description of which will be omitted herein.

In a state where the second and third suction ports 41c and 41b are opened, the roller 22 initially rolls clockwise along the inner circumference of the cylinder 21 by the rotational motion of the driving shaft 13. In the course of the initial rolling, the fluid fed until the roller reaches the second suction port 41c is not compressed and discharged out of the cylinder 21 through the second suction port 41c by the roller 22 as shown in FIG 12a. As a result, as shown in FIG. 12b, the compression of the fluid is initiated after the roller passes over the second suction port 41c. At this point, a space 29b between the second suction port 41c and the vane 23 is under

vacuum. However, as described above, when the roller starts rolling, the third suction port 41b communicates with the first opening 61a. Accordingly, the vacuum is released to reduce the power loss and the noise.

As the roller 22 further revolves, the space 29a is reduced to compress the fluid. In the course of this process, the vane 23 elastically moves by the elastic member 23a to divide the fluid chamber 29 in the two sealed spaces 29a and 29b.

At this point, fresh fluid is fed to the space 29b through the second and third suction ports 41c and 41b and is compressed in the next stroke.

When fluid pressure in the space 29a is increased above a predetermined level, the first discharge valve 27c is opened, as a result of which, as shown in FIG. lie, the fluid in the space 29b is discharged through the second discharge port 27a. After the fluid is completely discharged, the first discharge valve 27c closes the first discharge port 27a by using its self-elastic force.

After one stroke is completed as described above, the roller 22 continuously revolves clockwise to repeatedly discharge fluid through the process of the stroke.

In the clockwise stroke, the roller 22 compresses the fluid while revolving from the second suction port 41c to the first discharge port 27a. As described above, since the first suction port 41a and the second discharge port 27b are adjacently disposed on the both sides of the vane 23 while opposing each other, the fluid is compressed by the variation of a portion of the volume of the fluid chamber 29 in the clockwise stroke, thereby obtaining a compression capacity less than that obtained in the counterclockwise stroke.

In the above clockwise and counterclockwise strokes, the compressed fluid discharged through the discharge ports 27a and 27b is directed to the muffler 30, and is then finally discharged out of the compressor through the spaces defined between the rotor 12 and the stator 11 and between the stator 11 and the case 1.

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 As described above, the rotary compressor of the present invention is designed to compress the fluid regardless of a rotational direction of the driving shaft and to vary the compression capacity according to the rotational direction of the driving shaft. Furthermore, the rotary compressor of the present invention is designed in a simple structure having suction and discharge ports that are properly aligned to be opened and closed according to the rotation direction. The rotary container of the present invention has a variety of advantages, as follows: First, in the conventional art, two compressors each having a different compression capacity and two inverters are associated to realize dual-compression capacity, complicating the structure and increasing the costs. However, in the present invention, the dual-compression capacity is realized by a single compressor using the less number of parts, thereby reducing the costs.

Second, the conventional compressor having a single compression capacity can be employed to a variety of application due to its capacity limitation. However, the compressor of the present invention can be applied to a variety of application due to its variable compression capacity.

Third, the inventive rotary compressor is designed to use an overall volume of the fluid chamber in generating the dual-compression capacity. This means that the maximum compression capacity of the inventive rotary compressor is identical to the conventional rotary compressor having an identical fluid chamber volume to that of the present invention. That is, the rotary compressor of the present invention can replace the conventional one without changing the design such as a size of the cylinder and increasing the costs; and Fourth, generally, fluid and lubricant are simultaneously supplied to the fluid chamber. At this point, if suction ports and a plenum are disposed on a lower portion of the cylinder, the lubricant cannot be effectively fed into the cylinder, but accumulated in the plenum. This may deteriorate the lubrication of the cylinder.

However, in the present invention, since all of the suction ports and the plenum are disposed on a lower portion of the cylinder, the above problems can be eliminated.