US20050019176A1

US20050019176A1 - Variable capacity scroll compressor

Info

Publication number: US20050019176A1
Application number: US10/832,300
Authority: US
Inventors: Dong Shin; Hong Park; Cheol Kim
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2003-07-26
Filing date: 2004-04-27
Publication date: 2005-01-27
Also published as: CN1576601A; CN100343519C; KR20050012633A; KR100557057B1

Abstract

Disclosed is a variable capacity scroll compressor including an intake passage connected to an intake chamber, an exhaust passage connected to an exhaust chamber, a bypass port formed through a wall defining a compression space, a bypass passage having a first end connected to the bypass port and a second end connected to the intake chamber that is in a low-pressure state, a check valve for selectively connecting the bypass passage to the bypass port, and a control valve for selectively applying one of low-pressure fluid and high-pressure fluid in the exhaust passage to the check valve to control the check valve to one of opening and closing positions.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a scroll compressor, and more particularly, to a variable capacity scroll compressor, which is configured to vary a compression capacity according to a simple operation of a system where the compressor is applied.
2. Description of the Related Art
Generally, a cooling system is applied to an air conditioner or a refrigerator to lower the temperature of an enclosed space by absorbing and discharging heat using refrigerant circulating a cooling cycle.
Such a cooling system is configured to perform a series of cycles of compression, condensation, expansion and vaporization of refrigerant. A scroll compressor is used to perform the compression cycle among the series of cycles.
Since the scroll compressor is disclosed in a plurality of published documents, the detailed description on the general structure and operation will be omitted herein.
The reason why the compression capacity of a scroll compressor should be varied will be described hereinafter.
A scroll compressor for a specific use is generally selected by considering the most disadvantageous operation condition when forecasting its use environment, for instance, the greatest compression capacity-requested condition (i.e., a heating operation of an air conditioner using heat pump).
However, it is general that the most disadvantageous condition does not nearly occur in an actual operation. In an actual operation of the compressor, a condition needing a small compression capacity (ex. cooling operation of air conditioner) not the most disadvantageous condition exists too.
Thus, when the compressor having a large compression capacity is selected considering the worst condition, the compressor is operated under the low-load condition during an operation period of the high-compression ratio, thereby deteriorating an overall operation efficiency of the system.
Therefore, in order to improve the overall operating efficiency even under a normal operating condition and to accept the operational condition under the most disadvantageous condition, there is a need for a compressor that has a variable compression capacity.
To vary the compression capacity of the scroll compressor, a method for electrically controlling an RPM of the compressor has been most widely used.
Such an electrical control method has an advantage of effectively varying the compression capacity. However, additional components, for instance, an inverter for accurately controlling the RPM of a motor, are required. Furthermore, when the motor rotates with a relatively high RPM, it is difficult to ensure a reliability of frictional portions.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a variable capacity scroll 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 variable capacity scroll compressor that can vary a compression capacity using a bypass function in a state where a compressor motor rotates at a constant RPM.
Another object of the present invention is to provide a variable capacity scroll compressor that can vary a compression capacity by operating a valve using either uncompressed low-pressure fluid or compressed high-pressure fluid.
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 in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a variable capacity scroll compressor including: a bypass port formed through a wall defining a compression space; a bypass passage having a first end connected to the bypass port and a second end connected to an intake chamber that is in a low-pressure state; a check valve for selectively connecting the bypass passage to the bypass port; and a control valve for selectively applying one of low-pressure fluid and high-pressure fluid in an exhaust passage to the check valve to control the check valve to one of opening and closing positions.
In another aspect of the present invention, there is provided a variable capacity scroll compressor including: a bypass port formed on a compression path defined between first and second scroll members; a check valve for controlling opening and closing states of the bypass port; and a bypass controller for controlling an opening/closing operation of the check valve using at least pressure applied from an exhaust passage.
In still another aspect of the present invention, there is provided a variable capacity scroll compressor including: a bypass port formed on a compression path defined between first and second scroll members; a float valve for controlling opening and closing states of the bypass port; and a bypass controller for controlling an operation of the check valve by high-pressure fluid applied from an exhaust passage.
According to the present invention, the capacity variation of the scroll compressor can be easily varied without adding additional components.
The present invention has an advantage the inventive compressor can be effectively used when it is employed to a system where a capacity variation is required.
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 THE 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 sectional view of a scroll compressor according to a first embodiment of the present invention;
FIG. 2 is a bottom view of a stationary scroll member depicted in FIG. 1;
FIG. 3 is an enlarged view of a portion “A”of FIG. 1, in which a bypass port is closed;
FIG. 4 is a view conceptually illustrating a state of a scroll member when a bypass port is closed;
FIG. 5 is an enlarged view of a portion “A” of FIG. 1, in which a bypass port is opened;
FIG. 6 is a view conceptually illustrating a state of scroll member when a bypass port is opened; and
FIG. 7 is a sectional view of a scroll compressor according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF 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 shows a sectional view of a scroll compressor according to an embodiment of the present invention.
Referring to FIG. 1, the inventive scroll compressor includes a conventional compressing part, a bypass part for varying a compression capacity, and a bypass control part for controlling the bypass part.
The conventional compressing part includes a seal case 11 for defining an enclosed chamber, a seal plate 12 disposed in the seal case 11 to divide the sealed chamber into a low-pressure intake chamber 13 and a high-pressure exhaust chamber 14, an intake passage 22 connected to the intake chamber 13 to supply fluid to be compressed to the intake chamber 13, an exhaust passage 23 connected to the exhaust chamber 14 to exhaust compressed fluid out of the exhaust chamber 14, a stationary scroll member 15 fixed on an inner circumference of the seal case 11, a driving shaft 19 extending from a motor (not shown) and having an eccentric upper end, a orbiting scroll member 16 associated with the driving shaft 19, a stationary spiral wrap 17 formed on the stationary scroll member 15, a rotational spiral wrap 18 defining the fluid compressing path by surface-contacting the stationary spiral wrap 17, a bearing 21 for stably supporting the driving shaft 19, and a central exhaust passage 26 formed through a central axis of the stationary scroll member 15 to direct the compressed fluid to the exhaust chamber 14.
The bypass part includes a bypass port 24 formed through a portion of the stationary scroll member 15, a check valve 25 formed on a rear side of the bypass port 24 to control the flowing direction of the fluid, and a bypass passage 31 branched off from the check valve 25 to allow the fluid exhausted through the bypass port 24 to be directed to the intake chamber 13.
The bypass control part includes a control passage 30 for forming control pressure for controlling an opening/closing operation of the check valve 25 and a control valve 29 for allowing the control pressure formed on the control passage 30 to be selectively supplied from one of the low-pressure and high- pressure passages 27 and 28. The control passage 30 is formed penetrating the seal plate 12 to communicate with a compression space of the conventional compressing part.
Particularly, the low-pressure passage 27 has a first end connected to the control valve 29 and a second end connected to the intake passage 22 so that low-pressure of the intake passage 22 can be applied to the low-pressure passage 27. The high-pressure passage 28 has a first end connected to the control valve 29 and a second end connected to the exhaust passage 23 so that high-pressure of the exhaust passage 23 can be applied to the high-pressure passage 28.
Meanwhile, the check valve 25 may be formed of a float valve having a floating member moving in a direction where pressure is applied to change a passage connection state.
For example, as shown in the drawing, a cylindrical member is disposed in a cylindrical housing, being movable in a direction where low-pressure is applied.
Alternatively, a check ball may be movably disposed in a housing so that a fluid passage hole can be opened or closed by the check ball. That is, any types of valves that are designed to be controlled by pressure can be employed to the present invention.
In addition, the control valve 29 can be formed of a solenoid valve controlled by a predetermined controller.
The operation of the above described variable capacity scroll compressor will be described hereinafter.
When the driving shaft 19 is rotated by the motor (not shown), the orbiting scroll member 16 associated with the driving shaft 19 rotates. At this point, the stationary scroll member 15 is in a fixed state.
When the orbiting scroll member 16 rotates, low-pressure fluid stored in the intake chamber 13 is directed into a space defined between the rotational spiral wrap 18 formed on the orbiting scroll member 16 and the stationary spiral wrap 17 formed on the stationary scroll member 15, and is then compressed in the space.
The compressed fluid is directed into the exhaust chamber 14 through the central exhaust passage 26 formed through the central axis of the stationary scroll member 15, and the high-pressure fluid in the exhaust chamber 14 is exhausted through the exhaust passage 23.
Meanwhile, when the check valve 25 is closed (when the check valve 25 is moved downward in the drawing), the fluid cannot be exhausted through the bypass port 24. However, when the check valve 25 is opened (when the check valve 25 is moved upward in the drawing), the fluid is exhausted through the bypass port 24, and is then bypassed into the intake chamber 13 through the bypass passage 31. Therefore, when the check valve 25 is opened, the compression capacity is reduced.
To control the operation of the check valve 25, the bypass control part further includes a control passage, one end of which is connected to the check valve 25 to applied control pressure to the check valve 25. The control valve 29 is formed on the other end of the control passage 30. By the control valve 29, one of the fluid pressures from the low-pressure and high- pressure passages 27 and 28 is selected and applied to the control passage 30.
Particularly, the low-pressure and high- pressure passages 27 and 28 are respectively connected to the intake and exhaust passages 22 and 23 such that low-pressure fluid that is not compressed in the conventional compressing part and high-pressure fluid that is compressed in the conventional compressing part can be respectively supplied to the low-pressure and high- pressure passages 27 and 28. As a result, the control passage 30 is selectively supplied with one of the low-pressure and high-pressure fluids in the respective low-pressure and high- pressure passages 27 and 28.
Describing more in detail, when the high-pressure passage 28 is connected to the control passage 30 by the control valve moved upward in FIG. 1, since the control passage 30 is supplied with the high-pressure, the check valve 25 is closed by moving downward. When the check valve 25 is closed, since the bypass port 24 is closed, the fluid being compressed cannot be bypassed. As a result, a relatively large amount of fluid can be compressed without any compression capacity loss.
When the low-pressure passage 27 is connected to the control passage 30 by the control valve moved downward FIG. 1, since the low-pressure is applied to the control passage 30, the check valve 25 is opened by moving upward in FIG. 1. That is, pressure of fluid being compressed by a mutual operation of the scroll members 15 and 16 is lower than that in the intake pressure 22, the check valve 25 that is the floating valve is opened.
In addition, when the check valve 25 is opened, since the bypass port 24 is opened, the fluid being compressed is bypassed into the intake chamber 13 through the bypass passage 31. Therefore, the compression capacity is reduced as much as an amount of fluid bypassed.
FIG. 2 shows a bottom view of the stationary scroll member 15 depicted in FIG. 1.
Referring to FIG. 2, the stationary spiral wrap 17 is formed on the stationary scroll member 15, and the central exhaust passage 26 is formed through the central portion of the stationary spiral wrap 17. The bypass port 24 is formed on the scroll member in a compression space defined by the stationary spiral wrap 17, thereby allowing the fluid being compressed to be bypassed.
FIGS. 3 and 5 show enlarged views of a portion “A” in FIG. 1, and FIGS. 4 and 6 show views conceptually illustrating a scroll member according to opening and closing states of a bypass port. FIGS. 3 and 4 show a state where the bypass port is closed, and FIGS. 5 and 6 show a state where the bypass port is opened.
Referring first to FIG. 3, the bypass port 24 is formed at a position between spaced parts of the spiral wrap 17, and is in a closed state by the check valve 25. At this time, since high-pressure is applied to the check valve 25 through the control passage 30, the check valve 25 firmly closes the bypass port 24.
Referring to FIG. 4, when the bypass port 24 is closed, a first intake volume 41 that is a compression space defined between the stationary spiral wrap 17 and the orbiting spiral wrap 18 can be formed from a start position where the stationary spiral wrap 17 meets the orbiting spiral wrap 18.
The intake volume will be described more in detail hereinafter.
The intake volume defined between the stationary and orbiting spiral wraps 17 and 18 contacting each other may include two intake volumes.
One is a first intake space defined when an inner circumference of the stationary spiral wrap 17 meets an outer circumference of the orbiting spiral wrap 18. The first intake space can be illustrated as the first intake volume 41 depicted in FIG. 4.
The other is a second intake space (not shown) when an outer circumference of the stationary spiral wrap 17 meets an inner circumference of the orbiting spiral wrap 18. Although the second intake space is not shown in the drawing, it can be assumed that the second intake space can be formed by the orbiting operation of the orbiting spiral wrap 18.
A start point of the first intake space is defined on a location indicated by the reference character SC1 (Compress Start 1), and a start point of the second intake space is defined on a location indicated by the reference character SC2 (Compress Start 2. Since the start points SC1 and SC2 are not symmetrically located, this can be called an asymmetry operation mode. That is, when the scroll member is divided into half-and half based on the central portion of the scroll member and both the start points SC1 and SC2 are sided to one half, this can be called the asymmetric operation mode.
Referring to FIG. 5, when the bypass port 24 is opened by the check valve 25 moved upward, since the control passage 30 is supplied with the low-pressure as described above, the check valve 25 is opened to allow the fluid being compressed to be bypassed into the intake chamber 13 through the bypass port 24 and the pass passage 31.
Referring to FIG. 6, in a state where the bypass port 24 is opened, a start point of a second intake volume 42 defined between the stationary spiral wrap 42 and the rotational spiral wrap 18 is not defined on a location where the stationary spiral wrap 17 firstly meets the rotational spiral wrap 18. That is, it can be noted that a start point of the second intake volume 42 is defined on a location passed over the location where the bypass port 24 is formed.
The intake volume formed when the bypass port is opened will be described more in detail.
In this case, the intake volume defined between the stationary and rotational spiral wraps 17 and 18 contacting each other may be also divided into first and second volumes.
The first volume is a first intake space defined when an inner circumference of the stationary spiral wrap 17 meets an outer circumference of the rotational spiral wrap 18. The first intake space can be illustrated as the second intake volume 42 depicted in FIG. 6.
The second volume is a second intake space (not shown) when an outer circumference of the stationary spiral wrap 17 meets an inner circumference of the rotational spiral wrap 18. Although the second intake space is not shown in the drawing, it can be assumed that the second intake space can be formed by the rotational operation of the rotational spiral wrap 18.
In addition, since the bypass port 24 is formed near the inner circumference of the stationary spiral wrap, it does not interfere with the formation of the second intake space. However, the second intake space is formed only when the bypass port 24 is closed by a thickness of the rotational spiral wrap 18. That is, although the second intake space is not affected by the presence of the bypass port 24 by the rotational spiral wrap 18, an amount of fluid that is bypassed can be further varied in accordance with a thickness of the rotational spiral wrap 18 and a relative location of the bypass port 24 formed in the compression space. When the bypass port 24 is formed on a sidewall defining the compression space, the second intake space can be formed regardless of the thickness of the rotational spiral wrap.
In the beginning of the compression, a start point of the first intake space is defined on a location indicated by the reference character CS1, and a start point of the second intake space is formed on a location indicated by the reference character CS2. That is, the start points CS1 and CS2 are symmetrically located based on the centers of the scroll members 15 and 16. This can be called a symmetry operation mode.
Meanwhile, in order to realize the perfect symmetry operation mode, the bypass port 24 is formed on an opposite side of a spiral start point of the stationary spiral wrap 17 based on the center of the stationary scroll member 15.
When comparing the first intake volume 41 depicted in FIG. 4 with the second intake volume 42 depicted in FIG. 6, it can be noted that they are different from each other.
The first intake volume 41 is greater than the second intake volume 42. This shows that, in the asymmetry operation mode, much more fluid can be compressed. However, the second intake space formed in the asymmetry operation mode may be identical to that formed in the symmetry operation mode.
That is, since the volume of the intake space is varied according to a state (an open/close state) of the bypass port 24, the compression capacities defined by the first intake volume 41, formed when the bypass port is closed, and by the second intake volume 42, formed when the bypass port is opened, are difference from each other.
According to a series of tests, it was noted that, when the bypass port is formed on the location proposed in the drawing, the compression capacity obtained by performing the compression using a possible maximum volume tolerance (whole load) in a state where the bypass port 24 is closed is increased by 18% as compared with that obtained by performing the compression using a part of the compressible capacity (a partial load) in a state where the bypass port 24 is opened.
That is, the operation of the scroll compressor is changed into one of the symmetry and asymmetry operation modes according to a variety of factors such as the opening/closing state of the bypass port 24, the opening/closing state of the check valve 25, and the control state of the control valve 29. In addition, the intake volume of the scroll compressor is increased or decreased in accordance with the opening/closing state of the bypass port 24, thereby varying the compression capacity of the scroll compressor.
For example, when the control valve 29 is controlled such that the high-pressure passage 28 is connected to the control passage 30, the check valve 25 moves downward in the drawing, and the bypass port 24 is closed. The start points of the first and second intake spaces are asymmetrically located to operate the scroll compressor in the asymmetry operation mode, thereby increasing the compression capacity. Therefore, this asymmetry operation mode is suitable for, for example, a heating mode of an air conditioner where a relatively large amount of compression capacity is required.
When the control valve 29 is controlled such that the low-pressure passage 27 is connected to the control passage 30, the check valve 25 moves upward in the drawing, and the bypass port 24 is opened. The start points of the first and second intake spaces are symmetrically located to operate the scroll compressor in the symmetry operation mode, thereby reducing the compression capacity. Therefore, this symmetry operation mode is suitable for, for example, a cooling mode of the air conditioner where a relatively amount of compression capacity is required.
The application of the compressor of the present invention is not limited to the air conditioner that is used only for a description example. That is, the inventive compressor can be applied to any systems requiring a variable compression capacity.
FIG. 7 shows a scroll compressor according to a second embodiment of the present invention.
As shown in the drawing, the scroll compressor of this embodiment is identical to that of the first embodiment except for a connection structure around the control valve.
In detail, a control passage 52, a control valve 53, and a high-pressure passage 51 are same as those in the first embodiment. However, the low-pressure passage 27 that is selectively connected to the control passage by the control valve in the first embodiment is not formed in this embodiment.
When the low-pressure passage 27 is not formed, the low-pressure of the intake passage 22 is not applied to the control passage 52 even when the control valve 53 moves downward in the drawing.
At this point, since internal pressure of the control passage 52 is lower than medium-pressure of fluid being compressed in the conventional compressing part, the check valve 25 can be opened. That is, when the high-pressure that has been supplied via the high-pressure passage 51 and the control valve 53 is not supplied, the high-pressure fluid in the control passage 52 is exhausted through the check valve 25 to realize a pressure balance based on the check valve 25. Therefore, when the pressure balance is realized in the control passage 52 and the compression space is formed in a high-pressure environment by the operation of the scroll compressor, the check valve 25 that is in the pressure balance state is opened by the fluid being compressed.
As described above, by simply controlling the control valve, it is possible to conveniently allow the fluid being compressed to be bypassed. Particularly, the mainspring of the control of the bypass port is to selectively use low-pressure formed by fluid that is not sucked into the conventional compressing part and high-pressure formed by fluid compressed by the conventional compressing part.
Therefore, the structure of the scroll compressor can be more simplified, reducing the manufacturing costs.
The variable capacity scroll compressor according to the present invention has an advantage in that it is possible to vary the compression capacity in multi-stages using a bypass function, which can be realized by a simple structure, without varying the RPM of the compression motor.
In addition, since the valve for realizing the capacity variation of the scroll compressor is designed to be controlled by fluid pressure that is not still compressed in the compressing part and fluid pressure that is compressed in the compressing part without adding additional components, the manufacturing cost of the scroll compressor can be saved.
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.

Claims

1. A variable capacity scroll compressor comprising:

a bypass port formed through a wall defining a compression space;

a bypass passage having a first end connected to the bypass port and a second end connected to an intake chamber that is in a low-pressure state;

a check valve for selectively connecting the bypass passage to the bypass port; and

a control valve for selectively applying one of low-pressure fluid and high-pressure fluid in an exhaust passage to the check valve to control the check valve to one of opening and closing positions.

2. The variable capacity scroll compressor according to claim 1, wherein the control valve is connected to (a) a low-pressure passage connected to an intake passage, (b) a high-pressure passage connected to the exhaust passage, and (c) a control passage connected to the check valve, thereby controlling an application of pressure.

3. The variable capacity scroll compressor according to claim 1, wherein the check valve is a float valve.

4. The variable capacity scroll compressor according to claim 1, wherein the bypass port is formed at a stationary scroll member.

5. The variable capacity scroll compressor according to claim 1, wherein the bypass port is formed at an orbiting scroll member.

6. The variable capacity scroll compressor according to claim 1, wherein the control valve is a solenoid valve.

7. The variable capacity scroll compressor according to claim 1, wherein the bypass port is formed on an opposite side of a location, where a start point of the compression space is formed, based on a center of a scroll member.

8. The variable capacity scroll compressor according to claim 1, wherein the bypass port is formed at a location where the bypass port can be closed by a rotational scroll wrap.

9. The variable capacity scroll compressor according to claim 1, wherein the low-pressure fluid is supplied through an intake passage of the compressor.

10. The variable capacity scroll compressor according to claim 1, wherein the control valve is connected to (a) a high-pressure passage connected to the exhaust passage and (b) a control passage connected to the check valve, thereby controlling an application of pressure applying.

11. The variable capacity scroll compressor according to claim 1, wherein the control passage is formed penetrating a seal plate dividing a low-pressure side from a high-pressure side.

12. A variable capacity scroll compressor comprising:

a bypass port formed on a compression path defined between first and second scroll members;

a check valve for controlling opening and closing states of the bypass port; and

a bypass controller for controlling an opening/closing operation of the check valve using at least pressure applied from an exhaust passage.

13. The variable capacity scroll compressor according to claim 1, wherein the bypass controller comprises:

a control valve for selectively supplying one of fluid pressure of an intake passage and fluid pressure of the exhaust pressure; and

a control passage having opposite ends respectively connected to the control valve and the check valve to apply the fluid pressure supplied from the control valve to the check valve.

14. The variable capacity scroll compressor according to claim 12, wherein the bypass controller comprises:

a control valve for selectively supplying fluid pressure of the exhaust passage; and

15. The variable capacity scroll compressor according to claim 12, wherein fluid being compressed is exhausted to an intake chamber through the bypass port.

16. The variable capacity scroll compressor according to claim 12, wherein the bypass port is designed to bypass fluid compressed in at least one of two intake spaces.

17. The variable capacity scroll compressor according to claim 12, wherein the bypass port is defined between an inner circumference of a rotational scroll wrap formed on the first scroll member and an outer circumference of a rotational scroll wrap formed on the second scroll member.

18. The variable capacity scroll compressor according to claim 12, wherein the check valve comprises a check ball that is designed to freely move in a cavity by fluid pressure.

19. A variable capacity scroll compressor comprising:

a float valve for controlling opening and closing states of the bypass port; and

a bypass controller for controlling an operation of the check valve by high-pressure fluid applied from an exhaust passage.

20. A variable capacity scroll compressor according to claim 19, wherein, in order to control the operation of the check valve, low-pressure fluid may be further applied to the bypass controller from an intake passage.

21. A variable capacity scroll compressor according to claim 19, wherein the bypass port is formed at a location allowing for both of symmetry and asymmetry operation modes of the scroll compressor.

22. A variable capacity scroll compressor according to claim 19, wherein the bypass port is formed on a sidewall defining a compression space.