WO2012096445A1

WO2012096445A1 - Scroll compressor with split type orbiting scroll

Info

Publication number: WO2012096445A1
Application number: PCT/KR2011/009616
Authority: WO
Inventors: Inho Won; Yanghee CHO; Byeongchul Lee; Kitae JANG
Original assignee: Lg Electronics Inc.
Priority date: 2011-01-11
Filing date: 2011-12-14
Publication date: 2012-07-19
Also published as: CN103261695A; KR20120081489A; KR101821708B1; CN103261695B

Abstract

A scroll compressor with a split type orbiting scroll includes a case, a fixed scroll installed in the case, a wrap portion configured to form a compression chamber by being engaged with the fixed scroll, a base portion coupled to the wrap portion so as to have a restricted rotation in a circumferential direction, a driving motor coupled to a rear surface of the base portion and eccentrically rotating the base portion and the wrap portion, a main frame installed in the case and supporting the base portion, and a rotation preventing mechanism coupled to one of the base portion and the wrap portion, and configured to prevent the wrap portion and the base portion from rotating with respect to the main frame.

Description

SCROLL COMPRESSOR WITH SPLIT TYPE ORBITING SCROLL

This specification relates to a scroll compressor with a split type orbiting scroll, and particularly, to a scroll compressor capable of performing a compression operation while an orbiting scroll performs an orbital motion with respect to a fixed scroll.

Generally, a scroll compressor is a compressor for compressing a refrigerant gas by changing a volume of a compression chamber formed by a pair of scrolls facing each other. This scroll compressor is being widely applied to an air conditioner due to its higher efficiency, lower vibration, lower noise, smaller size and lighter weight than a reciprocating compressor or a rotary compressor.

This scroll compressor may be classified into a low pressure type and a high pressure type according to a method for supplying a refrigerant into a compression chamber. More concretely, the low pressure type scroll compressor is configured such that a refrigerant is indirectly sucked into a compression chamber through an inner space of a case. Here, the inner space of the case is divided into a suction space and a discharge space. On the other hand, the high pressure type scroll compressor is configured such that a refrigerant is directly sucked into a compression chamber not through an inner space of a case, and is discharged to the inner space of the case. Here, the inner space of the case is implemented as a discharge space.

The scroll compressor may be also categorized into a tip seal method and a back pressure method according to a sealing method of a compression chamber. More concretely, the tip seal method is configured such that a tip seal installed on a wrap end of one scroll is upward moved to be adhered to an end plate of an opposite scroll when a compressor is operated. On the other hand, the back pressure method is configured such that a back pressure chamber is formed on a rear surface of one scroll and the scroll is adhered to an opposite scroll by a pressure in the back pressure chamber as oil or a refrigerant having an intermediate pressure is introduced into the back pressure chamber. Generally, the tip seal method is applied to a low pressure type scroll compressor, whereas the back pressure method is applied to a high pressure type scroll compressor.

The orbiting scroll is provided with a rotation shaft of a driving motor coupled to one side surface thereof, and a wrap engaged with a fixed scroll on another side surface thereof. The orbiting scroll is rotated in a state that two side surfaces thereof come in contact with the fixed scroll and a main frame.

In order to prevent a vibration and to minimize a frictional loss, the orbiting scroll is required to have a precisely processed shape. For this, a bearing surface contacting the main frame is firstly processed, and then a wrap portion is processed. This may require a lot of time during an operation, and cause damage of the bearing surface when processing the wrap portion. Furthermore, since shapes and sizes of the orbiting scroll and the fixed scroll, especially a shape and a size of the wrap portion have to be differently designed according to a capacity of a compressor, it takes a lot of time to design and fabricate the orbiting scroll.

Therefore, an aspect of the detailed description is to provide a scroll compressor capable of more easily fabricating an orbiting scroll.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, a scroll compressor includes a case, a fixed scroll installed in the case, a wrap portion configured to form a compression chamber by being engaged with the fixed scroll, a base portion coupled to the wrap portion so as to have a restricted rotation in a circumferential direction, a driving motor coupled to a rear surface of the base portion and eccentrically rotating the base portion and the wrap portion, a main frame installed in the case and supporting the base portion, and a rotation preventing mechanism coupled to one of the base portion and the wrap portion, and configured to prevent the wrap portion and the base portion from rotating with respect to the main frame.

Differently from the convention orbiting scroll which is integrally formed, the orbiting scroll of the present invention may be divided into a wrap portion and a base portion. This may allow the wrap portion and the base portion to be separately fabricated from each other. Accordingly, the base portion may be commonly utilized in a plurality of compressors having different capacities, and thus the orbiting scroll may be fabricated more easily.

The wrap portion and the base portion may be coupled to each other in an arbitrary manner such as bolt-coupling. For instance, the wrap portion and the base portion may be coupled to each other by using keys. More concretely, key holes are formed at both sides of the wrap portion and the base portion, and keys may be inserted into the key holes. Alternatively, a key may be integrally formed at one side of the wrap portion and the base portion, and a key hole for coupling the key may be formed at another side of the wrap portion and the base portion.

The key may be formed in plurality in number, and the plurality of keys may be radially disposed at one side of the wrap portion and the base portion. The base portion may include a boss portion coupled to a rotation shaft of the driving motor, and a base flange disposed to face the wrap portion. As the rotation preventing mechanism, may be used an Oldham ring interposed between the base flange and the main frame.

More concretely, the rotation preventing mechanism may include a ring-shaped portion, a first protrusion formed on a bottom surface of the ring-shaped portion and coupled to the main frame, and a second protrusion formed on an upper surface of the ring-shaped portion and coupled to the base flange. A second protrusion recess engaged with the second protrusion may be formed on a bottom surface of the base flange.

The wrap portion may include a wrap flange facing the base portion, and an orbiting wrap engaged with a fixed wrap of the fixed scroll. In this case, the rotation preventing mechanism may be interposed between the fixed scroll and the wrap flange, and the orbiting wrap may be disposed in the rotation preventing mechanism.

The rotation preventing mechanism may include a ring-shaped portion, a first protrusion formed on an upper surface of the ring-shaped portion and coupled to the fixed scroll, and a second protrusion formed on a bottom surface of the ring-shaped portion and coupled to the wrap flange. A second protrusion recess engaged with the second protrusion may be formed on an upper surface of the wrap flange.

The present invention may have the following advantages.

Firstly, since the orbiting scroll is divided into two parts, a part of the orbiting scroll may be commonly used. This may facilitate a processing of the orbiting scroll, and a fabrication of a compressor.

Secondly, since the orbiting wrap and the bearing surface requiring a precise processing are separated from each other, the orbiting wrap and the bearing surface may be processed independently from each other. This may reduce the entire processing time, and may minimize damage of an existing processed part during a processing procedure.

Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from the detailed description.

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments and together with the description serve to explain the principles of the invention.

In the drawings:

FIG. 1 is a sectional view illustrating a scroll compressor according to a first embodiment of the present invention;

FIG. 2 is a partial enlarged view of a cut-out portion of a compression part of FIG. 1;

FIG. 3 is an exploded perspective view of an orbiting scroll of FIG. 1;

FIG. 4 is a sectional enlarged view of an orbiting scroll of FIG. 1;

FIGS. 5A to 5C are planar views schematically illustrating operation procedures of a scroll compressor of FIG. 1 according to a first embodiment of the present invention;

FIG. 6 is a graph illustrating a thrust force according to a position of a back pressure hole of an orbiting scroll of FIG. 1; and

FIG. 7 is a sectional view illustrating a scroll compressor according to a second embodiment of the present invention.

Description will now be given in detail of the exemplary embodiments, with reference to the accompanying drawings. For the sake of brief description with reference to the drawings, the same or equivalent components will be provided with the same reference numbers, and description thereof will not be repeated.

Hereinafter, a scroll compressor of the present invention will be explained in more details with reference to the attached drawings.

FIG. 1 is a sectional view illustrating a scroll compressor according to a first embodiment of the present invention, FIG. 2 is a partial enlarged view of a cut-out portion of a compression part of FIG. 1, and FIG. 3 is an exploded perspective view of an orbiting scroll of FIG. 1.

As shown in FIGS. 1 to 3, the scroll compressor of the present invention includes a case 1 having an inner space divided into a suction space 11, a lower pressure side and a discharge space 12, a high pressure side. A driving motor 2 configured to generate a rotational force is installed at the suction space 11 of the case 1. A main frame 3 is fixedly installed between the suction space 11 and the discharge space 12 of the case 1. A fixed scroll 4 is fixedly installed on an upper surface of the main frame 3. Between the main frame 3 and the fixed scroll, installed is an orbiting scroll 5 eccentrically-coupled to a crank shaft 23 of the driving motor 2. The orbiting scroll 5 forms a pair of compression chambers (P) which consecutively move, together with the fixed scroll 4. An Oldham ring 6 for preventing a rotation of the orbiting scroll 5 is installed between the fixed scroll 4 and the orbiting scroll 5.

A suction pipe 13 is coupled to the suction space 11 of the case 1 so as to be communicated therewith, and a discharge pipe 14 is coupled to the discharge space 12 of the case 1 so as to be communicated therewith.

Although not shown, the case is provided with a sealed discharge space, and is divided into a suction space (low pressure side) and a discharge space (high pressure side) by a discharge plenum fixedly-coupled to the fixed scroll 4. Alternatively, an inner space of the case may be divided into a suction space and a discharge space by a high-low pressure separation end plate (not shown) fixed to an upper surface of the fixed scroll and adhered to an inner circumferential surface of the case.

The fixed scroll 4 consists of an end plate 41, and a fixed wrap 42 protruding from a bottom surface of the end plate 41 and formed in an involute shape so as to form a compression chamber (P) together with an orbiting wrap 52 of the orbiting scroll 5. A suction port (not shown) is formed on an outer circumferential surface of the end plate 41 of the fixed scroll 4 such that the suction space 11 of the case 1 is communicated with the compression chamber (P). A discharge port 44 is formed at a central part of the end plate 41 of the fixed scroll 4 such that the discharge space 12 of the case 1 is communicated with the compression chamber (P). Unexplained reference numeral 7 denotes a sub-frame, 8 denotes a discharge valve, 21 denotes a stator and 22 denotes a rotor.

In the present invention, a refrigerant is introduced into the suction space 11, a low pressure side of the case 1, through the suction pipe 13 from the outside. Then, the low-pressure refrigerant in the suction space 11 is introduced into the fixed scroll 4 through the suction port of the fixed scroll 4, and then is moved to central parts of the orbiting scroll and the fixed scroll by the orbiting scroll 5. Then, the refrigerant is compressed to be discharged to the discharge space 12 of the case through the discharge port 44 of the fixed scroll 4. These processes are repeatedly performed.

As shown in FIGS. 2 and 3, the orbiting scroll 5 may be divided into two parts. More concretely, the orbiting scroll 5 consists of a wrap portion 50 engaged with the fixed scroll, and a base portion 60 coupled to the wrap portion 50. The wrap portion 50 has an orbiting wrap 52 which forms a compression chamber by being engaged with the fixed wrap 42, and a wrap flange 54 integrally formed with the orbiting wrap 52. The wrap flange 54 is formed to have a disc shape, and key-shaped portions 56 to be coupled to the base portion 60 are formed at two sides of a bottom surface of the wrap flange 54.

The base portion 60 is coupled to the wrap portion 50 with facing the bottom surface of the wrap flange 54. More concretely, the base portion includes a base flange 64 formed in a disc shape like the wrap flange 54, and a boss portion 68 formed on a bottom surface of the base flange 64 and coupled to the crank shaft 23.

Key holes 66 coupled to the key-shaped portions 56 are formed at two edges of an upper surface of the base flange 64, respectively. As the key-shaped portions are inserted into the key holes, the wrap portion 50 is moveable with respect to the base portion 60 in a direction of the crank shaft, but is not moveable in a radius direction or a circumferential direction of the base portion 60. Motions of the wrap portion 50 in an axial direction are restricted by a gap between the fixed scroll and the main frame 3. Accordingly, the key-shaped portions 56 maintain an inserted state into the key holes 66. More concretely, the wrap portion 50 and the base portion 60 may be stably coupled to each other by inserting the key-shaped portions into the key holes, without using bolt-coupling or welding.

The Oldham ring 6 for preventing a rotation of the orbiting scroll 5 is coupled to a bottom surface of the base portion 60. More concretely, the Oldham ring 6 is provided with a ring-shaped portion 6a contacting a bottom surface of the base flange 64. A pair of first protrusions 6b having a phase difference of 180 from each other are formed at both sides of a bottom surface of the ring-shaped portion 6a. The first protrusions 6b are inserted into first protrusion recesses 3a of the main frame 3. A pair of second protrusions 6c having a phase difference of 180 from each other are formed at both sides of an upper surface of the ring-shaped portion 6a. The second protrusions 6c are inserted into second protrusion recesses 64a formed on a bottom surface of the base flange 64.

Under these configurations, even if a rotational force of the crank shaft 23 is transmitted to the base portion 60, the base portion 60 performs an orbital motion, in a state of being prevented from rotating due to the Oldham ring 6. And, the wrap portion 50 coupled to the base portion 60 so as to have a restricted motion in a radius direction also performs an orbital motion together with the base portion 60.

A back pressure chamber 62 of which inner space is divided by an O-ring 62a is formed at a central portion of an upper surface of the base flange 64. Referring to FIG. 4, the back pressure chamber 62 is disposed between a bottom surface of the wrap flange 54 and an upper surface of the base flange 64. An inner space of the back pressure chamber 62 is blocked from the low pressure side 11 by the O-ring 62a insertion-fixed to the base flange 64. A back pressure hole 54a through which the inner space of the back pressure chamber 62 and the compression chamber are communicated with each other is penetratingly formed at the base flange 64.

While sucking and compressing a refrigerant, a compressed refrigerant in the compression chamber is partially introduced into the back pressure chamber via the back pressure hole 54a. Since an inner pressure of the back pressure chamber is higher than a peripheral pressure of the base flange 64, the base portion 60 is upward moved from the wrap portion 50 in an axial direction. This may allow a sealing operation to be performed between a bottom surface of the fixed scroll and the orbiting wrap 52.

Here, the inner pressure of the back pressure chamber may be determined according to a position of the back pressure hole. More concretely, when the back pressure hole is moved to approach to a central part of the orbiting wrap 52 of the orbiting scroll, the inner pressure of the back pressure chamber is increased. On the other hand, when the back pressure hole is moved toward outside of the orbiting wrap 52 of the orbiting scroll, the inner pressure of the back pressure chamber is decreased.

FIGS. 5A to 5C are planar views schematically illustrating processes for compressing a refrigerant by the orbiting wrap and the fixed wrap according to a first embodiment of the present invention. Here, the solid line corresponds to a center line of the fixed wrap 42, and the dotted line corresponds to a center line of the orbiting wrap 52. FIG. 5C illustrates an operation to start a discharge process as a pressure in a compression chamber reaches a discharge pressure. As aforementioned, the pressure in the compression chamber formed by the orbiting wrap and the fixed wrap is consecutively changed during a compression process. Accordingly, a pressure on an arbitrary point of the orbiting wrap is also consecutively changed in one compression cycle.

For instance, when the back pressure hole is positioned at a point of a where a discharge pressure is applied during a compression process, the same pressure as the discharge pressure is applied to the back pressure chamber. In this case, a thrust force between a bottom surface of the fixed scroll and the orbiting wrap is large due to an excessive back pressure, resulting in great loss due to friction. Furthermore, a discharge pressure becomes different according to the amount of a compression load applied to the compressor. Accordingly, when the back pressure hole is positioned at a point of 'a' where a discharge pressure is applied, the thrust force becomes different according to a load. This may influence on a performance of the compressor. More concretely, the point of 'a' is within a range of a discharge start angle.

A point of 'b' indicates a position where a discharge pressure is applied for a predetermined time and an intermediate pressure between a suction pressure and a discharge pressure is applied for the rest time. Accordingly, when the back pressure hole is formed at the point of 'b' a proper back pressure may be obtained. Furthermore, even if a discharge pressure is changed due to a load change, etc., the discharge pressure may be compensated to some degrees due to the intermediate pressure. This may reduce influence on a performance of the compressor due to a load change. The present inventor has certified that the point of b is within a range of 180°, an involute phase difference from a discharge start angle of the orbiting wrap.

The point of 'c' indicates a position where only an intermediate pressure is applied during a compression process. When the back pressure hole is formed at the point of 'c' a back pressure is too low to have a difficulty in implementing a high sealing performance. This may cause leakage of a refrigerant.

FIG. 6 is a graph illustrating each thrust force under conditions of a low load, an over load, a high differential pressure and a high pressure ratio when the back pressure hole is positioned at the points of 'a' and 'b'.

Referring to FIG. 6, when the back pressure hole is positioned at the point of 'a' an excessive thrust force is generated under a condition of a low load, and thrust forces under the respective conditions have a large deviation from one another. On the other hand, when the back pressure hole is positioned at the point of 'b' a small thrust force is generated under a condition of a low load, and thrust forces under the respective conditions have a small deviation from one other.

Differently from the first embodiment, the Oldham ring may be coupled to the fixed scroll 4 as shown in FIG. 7. FIG. 7 is a sectional view illustrating a scroll compressor according to a second embodiment of the present invention. Referring to FIG. 7, the Oldham ring 6 is installed on the wrap portion 50 of the orbiting scroll, more concretely, on an upper surface of the wrap flange 54. For this, first protrusion recesses 4a for inserting the first protrusions 6b of the Oldham ring 6 are formed on a bottom surface of the fixed scroll 4. This may fix the Oldham ring 6 so as not to rotate with respect to the fixed scroll.

Second protrusions (not shown) of the Oldham ring 6 are inserted into second protrusion recesses (not shown) of the wrap flange 54.

Differently from the methods shown in the first and second embodiments, the wrap portion and the base portion may be coupled to each other by welding or by using bolts. In this case, the wrap portion may be fixed so as not to be moveable with respect to the base portion. And, the Oldham ring may be coupled to an upper surface of the wrap portion or a bottom surface of the base portion.

The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present disclosure. The present teachings can be readily applied to other types of apparatuses. This description is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments.

As the present features may be embodied in several forms without departing from the characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.

Claims

A scroll compressor, comprising:

a case;

a fixed scroll installed in the case;

a wrap portion configured to form a compression chamber by being engaged with the fixed scroll;

a base portion coupled to the wrap portion so as to have a restricted rotation in a circumferential direction;

a driving motor coupled to a rear surface of the base portion, and configured to eccentrically rotate the base portion and the wrap portion;

a main frame installed in the case, and configured to support the base portion; and

a rotation preventing mechanism coupled to one of the base portion and the wrap portion, and configured to prevent the wrap portion and the base portion from rotating with respect to the main frame.
The scroll compressor of claim 1, wherein the wrap portion and the base portion are coupled to each other by using keys.
The scroll compressor of claim 2, wherein a key is integrally formed at one side of the wrap portion and the base portion, and a key hole for coupling the key is formed at another side of the wrap portion and the base portion.
The scroll compressor of claim 3, wherein the key is formed in plurality in number, and the plurality of keys are radially disposed at one side of the wrap portion and the base portion.
The scroll compressor of claim 1, wherein the base portion comprises:

a boss portion coupled to a rotation shaft of the driving motor; and

a base flange disposed to face the wrap portion.
The scroll compressor of claim 5, wherein the rotation preventing mechanism comprises:

a ring-shaped portion;

a first protrusion formed on a bottom surface of the ring-shaped portion, and coupled to the main frame; and

a second protrusion formed on an upper surface of the ring-shaped portion, and coupled to the base flange.
The scroll compressor of claim 6, wherein a second protrusion recess engaged with the second protrusion is formed on a bottom surface of the base flange.
The scroll compressor of claim 1, wherein the wrap portion comprises:

a wrap flange facing the base portion; and

an orbiting wrap engaged with a fixed wrap of the fixed scroll.
The scroll compressor of claim 8, wherein the rotation preventing mechanism comprises:

a ring-shaped portion;

a first protrusion formed on an upper surface of the ring-shaped portion, and coupled to the fixed scroll; and

a second protrusion formed on a bottom surface of the ring-shaped portion, and coupled to the wrap flange.
The scroll compressor of claim 9, wherein a second protrusion recess engaged with the second protrusion is formed on an upper surface of the wrap flange.