US20140271302A1 - Scroll compressor with a bypass - Google Patents

Abstract

An upper back pressure type scroll compressor having a bypass is provided. The scroll compressor may include a casing, a discharge cover, a main frame, a first scroll supported by the main frame, and a second scroll that forms a suction chamber, an intermediate pressure chamber, and a discharge chamber together with the first scroll. The second scroll may include a bypass hole that communicates with the intermediate pressure chamber. The scroll compressor may also include a back pressure chamber assembly coupled to an upper portion of the second scroll by a fastening device and a bypass valve to open and close the bypass hole. The back pressure chamber assembly may include a discharge path by which the discharge chamber and the discharge space may communicate with each other and a bypass valve to open and close the bypass hole.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)
• This application claims priority to Korean Application Nos. 10-2013-0028775, filed in Korea on Mar. 18, 2013, 10-2013-0028783 filed in Korea on Mar. 18, 2013, and 10-2013-0028791, filed in Korea on Mar. 18, 2013, as well as U.S. application Ser. Nos. ______ (Attorney Docket No. P-1232) filed in the U.S. on ______, and ______ (Attorney Docket No. P-1236), filed in the U.S. on ______, the contents of all of which are incorporated by reference herein in their entirety.
BACKGROUND
• 1. Field
• A compressor, and more particularly, a scroll compressor with a bypass are disclosed herein.
• 2. Background
• Scroll compressors are known. However, they suffer from various disadvantages.
• A scroll compressor refers to a compressor that utilizes a first or orbital scroll having a spiral wrap and a second or fixed scroll having a spiral wrap, the first scroll performing an orbital motion with respect to the second scroll. While the first scroll and the second scroll are engaged with each other in operation, a capacity of a pressure chamber formed therebetween may be reduced as the first scroll performs the orbital motion. Hence, the pressure of a fluid in the pressure chamber may be increased, and the fluid discharged from a discharge opening formed at a central portion of the second scroll.
• The scroll compressor performs a suction process, a compression process, and a discharge process consecutively while the first scroll performs the orbital motion. Because of operational characteristics, the scroll compressor may not require a discharge valve and a suction valve in principle, and its structure may be simple with a small number of components, thus making it possible to perform a high speed rotation. Further, as the change in torque required for compression is small and the suction and compression processes consecutively performed, the scroll compressor is known to create minimal noise and vibration.
• For the scroll compressor, an occurrence of leakage of a refrigerant between the first scroll and the second scroll should be avoided or kept at a minimum, and lubricity (lubrication characteristic) should be enhanced therebetween. In order to prevent a compressed refrigerant from leaking between the first scroll and the second scroll, an end of a wrap portion should be adhered to a surface of a plate portion. On the other hand, in order for the first scroll to smoothly perform an orbital motion with respect to the second scroll, resistance due to friction should be minimized. The relationship between the prevention of the refrigerant leakage and the enhancement of the lubricity is contradictory. That is, if the end of the wrap portion and the surface of the plate portion are adhered to each other with an excessive force, leakage may be prevented. However, in such a case, more friction between the parts may result, thereby increasing noise and abrasion. On the other hand, if the end of the wrap portion and the surface of the plate portion are adhered to each other with less than an adequate sealing force, the friction may be reduced, but the lowering of the sealing force may result in the increase of leakage.
• In order to solve such problems, a back pressure chamber having an intermediate pressure between a discharge pressure and a suction pressure may be formed on a rear surface of the first scroll or the second scroll. That is, the first scroll and the second scroll may be adhered to each other with proper force, by forming a back pressure chamber that communicates with a compression chamber having an intermediate pressure, among a plurality of compression chambers formed between the first scroll and the second scroll. With such a configuration, leakage of refrigerant may be prevented and lubricity enhanced.
• The back pressure chamber may be positioned on a lower surface of the first scroll or an upper surface of the second scroll. In this case, the scroll compressor with such a back pressure chamber may be referred to as a ‘lower back pressure type scroll compressor’ or an ‘upper back pressure type scroll compressor’ for convenience. The structure of the lower back pressure type scroll compressor is simple, and its bypass holes easily formed. However, as its back pressure chamber is positioned on the lower surface of the first scroll, the form and position of the back pressure chamber may change due to the orbital motion. This may cause the first scroll to tilt, resulting in the occurrence of vibration and noise. Further, an O-ring to prevent leakage of a compressed refrigerant may be rapidly abraded. The structure of the upper back pressure type scroll compressor is complicated. However, as the back pressure chamber of the upper back pressure type scroll compressor is fixed in form and position, the probability of the second scroll tilting is low, and sealing for the back pressure chamber is excellent.
• Korean Patent Application No. 10-2000-0037517 entitled Method For Processing Bearing Housing and Scroll Machine having Bearing Housing, which corresponds to U.S. Pat. No. 5,156,539 and U.S. Reissue Pat. No. 35,216, all of which are hereby incorporated by reference, discloses an example of such an upper back pressure type scroll compressor.FIG. 1 is a partial cross-sectional view of an upper back pressure type scroll compressor. Thescroll compressor1 ofFIG. 1 may include a first ororbital scroll30 configured to perform an orbital motion on amain frame20 fixedly-installed in acasing10 and a second orfixed scroll40 engaged with thefirst scroll30 to create a plurality of compression chambers upon the orbital motion. A back pressure chamber BP may be formed at an upper portion of thesecond scroll40, and afloating plate60 to seal the back pressure chamber BP may be installed so as to be slidable up and down along an outer circumferential surface of adischarge passage45. Adischarge cover2 may be installed at an upper surface of thefloating plate60, thereby dividing an inner space of thescroll compressor1 into a suction space (S) and a discharge space (D). A lip seal (not shown) may be installed between thefloating plate60 and the back pressure chamber BP, so that refrigerant may be prevented from leaking from the back pressure chamber BP.
• The back pressure chamber BP may communicate with one of the plurality of compression chambers, and may be at a receiving end of an intermediate pressure from the plurality of compression chambers. With such a configuration, pressure may be applied upward to thefloating plate60, and pressure may also be applied downward to thesecond scroll40. If thefloating plate60 moves upward due to pressure of the back pressure chamber BP, the discharge space D may be sealed as an end of thefloating plate60 contacts thedischarge cover2. In this case, thesecond scroll40 moves downward to be adhered to thefirst scroll30. With such a configuration, a gap between thesecond scroll40 and thefirst scroll30 may be effectively sealed.
• Korean Patent Application No. 10-2012-7023733, which corresponds to U.S. Patent Pub. No. 2011/0206548, both of which are hereby incorporated by reference, discloses a compressor having a valve assembly.FIG. 2 is a sectional view of a fixed or second scroll of an upper back pressure type scroll compressor. The compressor ofFIG. 2 may include ahub member76 positioned at a central portion of the back pressure chamber BP and formed to pass through the back pressure chamber BP in upper and lower directions, and avalve assembly28 disposed below thehub member76. With such a configuration,bypass holes90 and92 formed on an upper surface of thesecond scroll40 may be open and closed while thevalve assembly28 moves thehub member76 up and down. For example, thebypass holes90 and92 may be open when the intermediate pressure is higher than the discharge pressure, thus pushing thevalve assembly28 up. Accordingly, overload in the upper back pressure type scroll compressor may be prevented by alleviating the pressure imbalance using the bypass holes.
BRIEF DESCRIPTION OF THE DRAWINGS
• Embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements, and wherein:
• FIG. 1 is a cross-sectional view of an upper back pressure type scroll compressor;
• FIG. 2 is a cross-sectional view of a second scroll of an upper back pressure type scroll compressor;
• FIG. 3 is a cross-sectional view of an upper back pressure type scroll compressor having a back pressure discharge according an embodiment;
• FIG. 4 is a partial cut-out perspective view showing a coupled state between a second scroll and a back pressure chamber assembly ofFIG. 3;
• FIG. 5 is an exploded perspective view of the second scroll and the back pressure chamber assembly ofFIG. 3;
• FIG. 6 is a perspective view of the second scroll ofFIG. 3;
• FIG. 7 is a planar view of a lower surface of a back pressure plate ofFIG. 3;
• FIG. 8 is an enlarged cross-sectional view of a portion of the second scroll and the back pressure plate ofFIG. 3;
• FIG. 9 is a partial cut-out cross-sectional view for explaining operation of a check valve and a discharge valve ofFIG. 3;
• FIG. 10 is a partial cut-out view of the scroll compressor ofFIG. 3 with a retainer according to an embodiment;
• FIG. 11 is a perspective view of a bypass valve according to another embodiment;
• FIG. 12 is a cross-sectional view of a bypass valve according to another embodiment; and
• FIG. 13 is a perspective view of a bypass valve according to yet another embodiment.
DETAILED DESCRIPTION
• Description will now be given in detail of embodiments, with reference to the accompanying drawings. Where possible, like reference numerals have been utilized to indicate like elements, and repetitive disclosure has been omitted.
• Referring again toFIG. 2, overload in the upper back pressure type scroll compressor may be prevented by alleviating pressure imbalance using the bypass holes and associated components of the scroll compressor. However, as thehub member76 may be disposed in the back pressure chamber BP, the position of the bypass holes90,92 may not be set arbitrarily. That is, in order to obtain a sufficient back pressure with the back pressure chamber BP, the back pressure chamber BP should be formed at a predetermined position with a predetermined size. This may limit a size of thehub member76. Therefore, positions of the bypass holes90,92 may be restricted to a region below thehub member76.
• Further, the floatingplate60 should seal the back pressure chamber BP while contacting an inner surface of the back pressure chamber BP of thesecond scroll40 and an outer circumferential surface of thehub member76. In this case, a sealing performance of the floatingplate60 may be compromised due to a quality of surface processing performed on the outer circumferential surface of thehub member76, that is a processing allowance (tolerance) and a coupling allowance (tolerance) of thehub member76.
• Therefore, embodiments disclosed herein further provide a scroll compressor capable of forming bypass holes at arbitrary positions of the second scroll. Embodiments disclosed herein further provide a scroll compressor capable of using a bypass valve of a simple structure.
• FIG. 3 is a cross-sectional view of an upper back pressure type scroll having a bypass according to an embodiment.FIG. 4 is a partial cut-out perspective view showing a coupled state between a second scroll and a back pressure chamber assembly ofFIG. 3.FIG. 5 is an exploded perspective view of the second scroll and the back pressure chamber assembly ofFIG. 3.
• Referring toFIG. 3, ascroll compressor100 having a bypass according to an embodiment may include acasing110 having a suction space (S) and a discharge space (D), which are discussed hereinbelow. An inner space of thecasing110 may be divided into the suction space (S) and the discharge space (D) by adischarge cover102 installed above at an upper portion of thecasing110. A space above thedischarge cover102 may correspond to the discharge space (D), and a space below thedischarge cover102 may correspond to the suction space (S). A suction port (not shown) that communicates with the suction space (S) and a discharge port (not shown) that communicates with the discharge space (D) may be fixed to thecasing110, respectively, thereby sucking a refrigerant into thecasing110 or discharging a refrigerant outside of thecasing110, respectively.
• Astator112 and arotor114 may be provided below the suction space (S). Thestator112 may be fixed to an inner wall surface of thecasing110, for example, in a shrinkage fitting manner. Arotational shaft116 may be inserted into a central portion of therotor114, and may be rotated by power supplied from the outside.
• A lower side of therotational shaft116 may be rotatably supported by anauxiliary bearing117 installed below at a lower portion of thecasing110. Theauxiliary bearing117 may be supported by alower frame118 fixed to an inner surface of thecasing110, thereby stably supporting therotational shaft116. Thelower frame118 may be fixed to an inner wall surface of thecasing110, for example, by welding, and a bottom lower surface of thecasing110 may be used as an oil storage space. Oil stored in the oil storage space may be upward transferred upward by therotational shaft116, so that the oil may be uniformly supplied into thecasing110.
• An upper end of therotational shaft116 may be rotatably supported by amain frame120. Themain frame120 may be fixed to an inner wall surface of thecasing110, similar to thelower frame118. Amain bearing portion122 may protrude downward from a lower surface of themain frame120, and therotational shaft116 may be inserted into themain bearing portion122. An inner wall surface of themain bearing portion122 may serve as a bearing surface and support therotational shaft116 together with the aforementioned oil, so that therotational shaft116 may rotate in a smooth manner.
• A first ororbital scroll130 may be disposed on an upper surface of themain frame120. Thefirst scroll130 may include aplate portion132, which may have an approximate disc shape, and awrap134 spirally formed on one side surface of theplate portion132. Thewrap134 may form a plurality of compression chambers together with awrap144 of a fixed orsecond scroll140, which is discussed hereinbelow. Theplate portion132 of thefirst scroll130 may perform an orbital motion while supported by an upper surface of themain frame120. AnOldham ring136 may be installed between theplate portion132 and themain frame120, thereby preventing rotation of thefirst scroll130. Aboss portion138, into which therotational shaft116 may be inserted, may be formed on a lower surface of theplate portion132 of thefirst scroll130, thus allowing thefirst scroll130 to perform an orbital motion by a rotational force of therotational shaft116.
• Thesecond scroll140, which engages theorbital scroll130, may be disposed above thefirst scroll130. Thesecond scroll140 may be installed to be movable up and down with respect to thefirst scroll130. More specifically, thesecond scroll140 may be disposed on an upper surface of themain frame120 using, for example, a fastener, for example, threeguide pins104, fitted into themain frame120 inserted into three (3) guide holes141 formed on an outer circumference of thesecond scroll140.
• The guide holes141 may be formed at threepin supporting portions142 that protrude from an outer circumferential surface of a body portion of thesecond scroll140. The number of the guide pins104 or pin supportingportions142 may be arbitrarily set, and thus, the number is not limited to three.
• Thesecond scroll140 may include aplate portion143, which may have a disc shape. Thewrap144, which engages thewrap134 of thefirst scroll130, may be formed below theplate portion143. Thewrap144 may have a spiral shape, and adischarge opening145, through which a compressed refrigerant may be discharged, may be formed at a central portion of theplate portion143. Asuction opening146, through which a refrigerant disposed in the suction space (S) may be sucked, may be formed on a side surface of thesecond scroll140, so that the refrigerant may be sucked to thesuction opening146 by an interaction between thewrap144 and thewrap134.
• As discussed above, thewrap144 and thewrap134 form a plurality of compression chambers. As the plurality of compression chambers decrease in volume while orbiting toward thedischarge opening145, a refrigerant is compressed. As a result, a pressure of a compression chamber adjacent to thesuction opening146 may be minimized, and a pressure of a compression chamber that communicates with thedischarge opening145 may be maximized. A pressure of a compression chamber positioned between the two above-mentioned compression chambers may have an intermediate pressure halfway between a suction pressure adjacent thesuction opening146 and a discharge pressure adjacent thedischarge opening145. The intermediate pressure may be applied to a back pressure chamber (BP), which is discussed hereinbelow, and may press thesecond scroll140 toward thefirst scroll130. Therefore, an intermediatepressure discharge opening147, which may communicate with one of the intermediate pressure chambers, and through which a refrigerant may be discharged, may be formed at theplate portion143, referring toFIG. 5.
• An intermediatepressure sealing groove147a, into which an intermediate pressure O-ring147bthat prevents leakage of a discharged refrigerant having the intermediate pressure may be inserted, may be formed near the intermediatepressure discharge opening147. The intermediatepressure sealing groove147amay be formed in an approximately circular shape to enclose the intermediatepressure discharge opening147. However, the shape is not limited to the circular shape. Further, the intermediatepressure sealing groove147amay be formed at other than theplate portion143 of the fixedscroll140. For instance, the intermediatepressure sealing groove147amay be formed on a lower surface of aback pressure plate150, which is discussed hereinbelow.
• Bolt coupling holes148 for couplingbolts106, which couple theback pressure plate150 and thesecond scroll140, may be formed on theplate portion143 of thesecond scroll140. In this embodiment, the number of the bolt coupling holes148 is four, but embodiments are not so limited.
• Referring toFIG. 6, bypass holes149 may be formed at both sides of thedischarge opening145. The bypass holes149 may pass through theplate portion143, and extend up to the plurality of compression chambers formed by thewrap144 and thewrap134. The position of the bypass holes149 may be differently set according to an operating condition. The bypass holes149 may be formed to communicate with the compression chambers having a pressure 1.5 times higher than the suction pressure. The bypass holes149 may include two through-holes, and awall portion149athat encloses an outer circumferential portion of the two through-holes may be provided. Thewall portion149amay contact a valve body of a bypass valve, which is discussed hereinbelow, and thewall portion149amay provide a space in which a refrigerant discharged from the through-holes may stay temporarily.
• Avalve seat portion149bmay be formed near thebypass hole149. Thevalve seat portion149bmay provide a space through or in which a valve supporting portion of a bypass valve, which is discussed hereinbelow, may move, and may extend from an outer circumferential portion of thewall portion149ain one direction.
• Referring toFIG. 5, thebypass valve124 may include avalve supporting portion124afixed to theplate portion143 of thesecond scroll140 by, for exmaple, rivets. Thevalve supporting portion124amay have a circular arc shape, and may be fixed to theplate portion143 by, for example, two rivets. Alternatively, a coupling device such as bolts or screws, rather than the rivets, may be used. Thevalve supporting portion124amay extend from portions to which the rivets are coupled in a ‘V’ shape. For convenience, the extending portions may be referred to asconnection portions124b.Valve bodies124cmay be formed at ends of theconnection portions124b. Thevalve body124cmay maintain contact with thewall portion149awhen no external force is applied thereto, and may have a diameter large enough to completely cover thewall portion149a.
• A back pressure chamber assembly may be installed on theplate portion143 of thesecond scroll140. The back pressure chamber assembly may include aback pressure plate150 and a floatingplate160, and may be fixed to an upper portion of theplate portion143 of thesecond scroll143. Theback pressure plate150 may have a ring shape, and may include a supportingplate152 that contacts theplate portion143 of thesecond scroll140. The supportingplate152 may have a ring shape, and may be formed to allow an intermediatepressure suction opening153 that communicates with the aforementioned intermediate pressure discharge opening147 to pass therethrough, referring toFIG. 7. Further, bolt coupling holes154 that communicate with the bolt coupling holes148 of theplate portion143 of thesecond scroll140 may be formed at or in the supportingplate152.
• An O-ring155amay be disposed between a lower surface of the supportingplate152 and an upper surface of thesecond scroll140. The O-ring155a, which may prevent a refrigerant from leaking from a gap between the supportingplate152 and thesecond scroll140, may be fitted into a ring-shapedgroove155 formed on an upper surface of thesecond scroll140. Further, the O-ring155amay be forcibly pressed while thesecond scroll140 and theback pressure plate150 are coupled to each other by thebolts106, thereby sealing a gap between thesecond scroll140 and theback pressure plate150. Alternatively, the ring-shapedgroove155 may be formed on a lower surface of the supportingplate152, rather than on thesecond scroll140.
• Theback pressure plate150 may include a first ring-shapedwall158 and a second ring-shapedwall159 formed to enclose an inner circumferential surface and an outer circumferential surface of the supportingplate152, respectively. The first ring-shapedwall158 and the second ring-shapedwall159 may form a space having a specific shape together with the supportingplate152. The space may implement the aforementioned back pressure chamber (BP). The first ring-shapedwall158 may extend upward from a central portion of the supportingplate152, and include anupper surface158amay cover an upper end of the first ring-shapedwall158. The first ring-shapedwall158 may have a cylindrical shape with an open end.
• An inner space of the first ring-shapedwall158 may communicate with thedischarge opening145, thereby implementing a portion of a discharge path along which a discharged refrigerant may be transferred to the discharge space (D). As shown inFIGS. 4 and 9, adischarge check valve108, which may have a cylindrical shape, may be disposed above thedischarge opening145. More specifically, a lower end of thedischarge check valve108 may be large enough to completely cover thedischarge opening145. With such a configuration, in a case in which thedischarge check valve108 contacts theplate portion143 of thesecond scroll140, thedischarge check valve108 may block thedischarge opening145.
• Thedischarge check valve108 may be installed in avalve guide portion158bformed at an inner space of the first ring-shapedwall158, and thevalve guide portion158bmay guide an up-and-down motion of thedischarge check valve108. Thevalve guide portion158bmay pass through the inner space of the first ring-shapedwall158. An inner diameter of thevalve guide portion158bmay be the same as an outer diameter of thedischarge check valve108, to guide an up-and-down motion of thedischarge check valve108 above thedischarge opening145. However, the inner diameter of thevalve guide portion158bmay not be completely equal to the outer diameter of thedischarge check valve108 to facilitate movement of thedischarge check valve108.
• A dischargepressure applying hole158cthat communicates with thevalve guide portion158bmay be formed at a central portion of an upper surface of the first ring-shapedwall158. The dischargepressure applying hole158cmay communicate with the discharge space (D). Accordingly, in a case in which a refrigerant from the discharge space (D) backflows to thedischarge opening145, pressure applied to the dischargepressure applying hole158cmay become higher than the pressure of thedischarge opening145. As a result, thedischarge check valve108 may move downward to block thedischarge opening145. If the pressure at thedischarge opening145 increases to be higher than the pressure at the discharge space (D), thedischarge check valve108 may move upward to open thedischarge opening145.
• One or more intermediate discharge opening(s)158dmay be formed outside of thevalve guide portion158b. The one of more intermediate discharge opening(s)158dmay provide a path through which a refrigerant discharged from thedischarge opening145 may move to the discharge space (D). In this embodiment, four (4)intermediate discharge openings158dare radially disposed; however, the number of theintermediate discharge openings158dmay vary. The one or more intermediate discharge opening(s)158dmay pierce through the first ring-shapedwall158 extending from its bottom to its top. The one or more intermediate discharge opening(s)158dand thevalve guide portion158bmay communicate with each other at a lower end of theback pressure plate150. That is, a steppedportion158emay be formed in a connection portion between the first ring-shapedwall158 and the supportingplate152. A discharged refrigerant reaches a space defined by the steppedportion158e, and then moves to the one or more intermediate discharge opening(s)158d.
• Agroove portion161 to form a bypass path may be formed outside the steppedportion158ein a radial direction. Thegroove portion161 may have a circular arc shape to enclose a portion of an outer circumferential portion of the steppedportion158e, and may be concaved from a lower surface of the supportingplate152. Along an outer circumferential portion of thegroove portion161 extending in a radial direction, regions adjacent to the bolt coupling holes154 may protrude inward in a radial direction. This may allow a peripheral portion of the bolt coupling holes154 to maintain a sufficient strength.
• An inner circumferential portion of thegroove portion161 in the radial direction may be open towards the steppedportion158e. With such a configuration, an inner space of thegroove portion161 may communicate with the one or more intermediate discharge opening(s)158dvia the steppedportion158e.
• Aportion161aof an upper surface of the groove portion161 (bottom surface inFIG. 7) may restrict an upward motion of thevalve body124c, which may be referred to as an open degree restrictor161afor convenience. The open degree restrictor161amay be in a shape corresponding to thevalve body124c, and may protrude toward the steppedportion158e. The open degree restrictor161amay be positioned above thevalve body124c. Accordingly, in a case in which thevalve body124cmoves upward by a distance more than a predetermined value, thevalve body124cmay contact the open degree restrictor161ato prevent thevalve body124cfrom moving any further.
• Instead of the open degree restrictor, an additional retainer may be provided. As shown inFIG. 10, aretainer161bto restrict an open degree of thevalve body124cwhen thevalve body124cis open may be formed on an upper surface of thegroove portion161.
• In some cases, the steppedportion158emay not be provided, but rather, a communication hole to communicate thevalve guide portion158band the one or more intermediate discharge opening(s)158dwith each other may be provided. In any case, a refrigerant having passed through thedischarge opening145 may not be discharged to the one or more intermediate discharge opening(s)158dif thedischarge check valve108 is closed. The steppedportion158emay be formed in theplate portion143 of thesecond scroll140, rather than on theback pressure plate150.
• The groove portion may be formed on an upper surface of theplate portion143 of thesecond scroll140, rather than on a lower surface of the supporting plate. In such a case, the bypass hole and the bypass valve may be formed on a bottom surface of the groove portion. With such a configuration, a length of the bypass hole may be shortened, and thus a dead volume formed by the bypass hole may be reduced.
• The second ring-shapedwall159 may be spaced from the first ring-shapedwall158 by a predetermined distance, and a firstsealing insertion groove159amay be formed on an inner circumferential surface of the second ring-shapedwall159. The firstsealing insertion groove159amay serve to receive and fix an O-ring159b, to prevent leakage of a refrigerant from a contact surface to a floatingplate160, which is discussed hereinbelow. Alternatively, the firstsealing insertion groove159amay be formed on an outer circumferential surface of the floatingplate160. However, the firstsealing insertion groove159aformed on the floatingplate160 may be less stable than the firstsealing insertion groove159aformed on theback pressure plate150, because the floatingplate160 continuously moves up and down.
• A space having an approximately ‘U’-shaped section may be formed by the first ring-shapedwall158, the second ring-shapedwall159, and the supportingplate152. The floatingplate160 may be installed to cover the space. The floatingplate160 may have a ring shape, and be configured such to have an inner circumferential surface thereof face an outer circumferential surface of the first ring-shapedwall158, and to have an outer circumferential surface thereof face an inner circumferential surface of the second ring-shapedwall159. With such a configuration, the back pressure chamber (BP) may be implemented, and the aforementioned O-rings159band162ainterposed between the respective facing surfaces may serve to prevent a refrigerant inside the back pressure chamber (BP) from leaking to the outside. Further,bolt accommodation portions106a, which may prevent interference with thebolts106, may be formed on a lower surface of the floatingplate160. However, in a case in which heads of thebolts106 do not protrude from a surface of the supportingplate152, thebolt accommodation portion106amay be omitted.
• A secondsealing insertion groove162 to receive and fix the O-ring162amay be formed on the inner circumferential surface of the floatingplate160. The secondsealing insertion groove162 may be provided at or in the inner circumferential surface of the floatingplate160, whereas the firstsealing insertion groove159amay be formed or in at the second ring-shapedwall159. This is because the first ring-shapedwall158 may have an insufficient margin to process the grooves due to thevalve guide portion158band the one or more intermediate discharge opening(s)158dformed therein, and a diameter of the first ring-shapedwall158 may be smaller than a diameter the second ring-shapedwall159. Alternatively, if the first ring-shapedwall158 has a large diameter and a sufficient margin to process the grooves, the secondsealing insertion groove162 may be formed in the first ring-shapedwall158.
• A sealingend164 may be provided at an upper end of the floatingplate160. The sealingend164 may protrude upward from the surface of the floatingplate160, and may have an inner diameter large enough not to cover the one or more intermediate discharge opening(s)158d. The sealingend164 may contact a lower side surface of thedischarge cover102, thereby sealing the discharge path so that a discharged refrigerant may be discharged to the discharge space (D) without leaking to the suction space (S).
• Hereinafter, an operation of a compressor according to an embodiment will be explained.
• When power is supplied to thestator112, therotational shaft116 may rotate. As therotational shaft116 rotates, thefirst scroll130 fixed to the upper end of therotational shaft116 may perform an orbital motion with respect to thesecond scroll140. As a result, the plurality of compression chambers formed between thewrap144 and thewrap134 may move toward thedischarge opening145, thereby compressing a refrigerant.
• If the plurality of compression chambers communicate with the intermediatepressure discharge opening147 before the refrigerant reaches thedischarge opening145, a portion of the refrigerant may be introduced into the intermediate pressure suction opening153 of the supportingplate152. Accordingly, an intermediate pressure may be applied to the back pressure chamber (BP) formed by theback pressure plate150 and the floatingplate160. As a result, pressure may be applied downward to theback pressure plate150, whereas pressure may be applied upward to the floatingplate160.
• Since theback pressure plate150 may be coupled to thesecond scroll140 by, for example, bolts, an intermediate pressure of the back pressure chamber (BP) may also influence thesecond scroll140. The floatingplate160 may move upward because thesecond scroll140 cannot move downward due to contact with theplate portion132 of thefirst scroll130. As the sealingend164 contacts the lower end of thedischarge cover102, the floatingplate160 stops moving. Then, as thesecond scroll140 is pushed toward thefirst scroll130 by the pressure of the back pressure chamber (BP), the refrigerant may be prevented from leaking from a gap between thefirst scroll130 and thesecond scroll140.
• If a pressure of thedischarge opening145 becomes higher than a pressure of the discharge space (D), thedischarge check valve108 may move upward so that the refrigerant may be discharged to the space defined by the steppedportion158e. Then, the refrigerant may be introduced into the one or more intermediate discharge opening(s)158d, and may then be discharged to the discharge space (D). If thescroll compressor100 is stopped or a pressure of the discharge space (D) temporarily increases, thedischarge check valve108 may move downward to block thedischarge opening145. This may prevent counter rotation of thesecond scroll140 resulting from backflow of the refrigerant.
• As thegroove portion161 communicates with the discharge path via the steppedportion158e, a discharge pressure may be applied to thegroove portion161. Pressure of the intermediate pressure chamber may be applied to a lower surface of thevalve body124c. In a normal operating condition, thevalve body124cmay maintain a contact state to thewall portion149aand thebypass hole149 may be closed, because the discharge pressure is greater than the intermediate pressure.
• However, if the suction pressure increases due to a change in operating condition, the intermediate pressure, which is normally about 1.5 times higher than the suction pressure, may become higher than the discharge pressure. In a case of the scroll compressor, the discharge pressure has a value obtained by multiplying the suction pressure with a compression ratio, while the compression ratio is fixed. Accordingly, if the suction pressure exceeds a proper range, the discharge pressure may excessively increases causing overload. In order to solve such an overload problem, if the discharge pressure inside the intermediate pressure chamber is excessive, refrigerant should be discharged even if it has not yet reached the discharge chamber.
• If the intermediate pressure increases to be higher than the discharge pressure, thevalve body124cmay move upward to open thebypass hole149. As thebypass hole149 is opened, the refrigerant disposed in the intermediate pressure chamber may be discharged into thegroove portion161, and may then move to the discharge space via the discharge path. With such a configuration, pressure of the intermediate pressure chamber may be prevented from excessively increasing.
• An operating condition of a system to which a compressor, for example, a scroll compressor, is to be applied may be predetermined. Accordingly, a range of the suction pressure and the discharge pressure of the compressor may be predicted. Based on the predicted range, a position or positions where the intermediate pressure chamber has an excessive pressure may be determined, and overload may be solved by forming bypass holes at those position(s).
• In the conventional art, if optimum positions of the bypass holes correspond to an outside of a hub member, the bypass holes cannot be formed at the necessary positions. However, with this embodiment, as the back pressure chamber assembly may be separated from the fixed plate, the bypass holes may be formed at any position on the plate portion of the second scroll. Further, as the bypass valve may be installed, overload may be effectively solved.
• The shape of the bypass valve is not limited to the illustrated example.
• FIG. 11 is a perspective view of a bypass valve according to an embodiment. InFIG. 11, the bypass valve has a structure in which thevalve bodies124cmay be connected to anedge portion124d. More specifically, thevalve supporting portions124amay be coupled to theplate portion143 of thesecond scroll140, for example, bybolts106, and may be connected to each other by theedge portion124d. The twoconnection portions124bmay be connected to a portion of thevalve supporting portions124a, and thevalve bodies124cmay be formed at ends of theconnection portions124b.
• According to this embodiment, the bypass valve may be fixed by bolts used to connect the second scroll and the back pressure plate to each other, without using an additional coupling device. Accordingly, this may simplify the assembly processes.
• FIG. 12 is a cross-sectional view showing a bypass valve according to another embodiment. InFIG. 12, avalve installation hole152amay be formed in thegroove portion161, and abypass valve220 may be installed in thevalve installation hole152a. Thebypass valve220 may include avalve body224 to open and close thebypass hole149 and astem222 formed on a rear surface of thevalve body224. Thestem222 may be installed so as to be movable up and down in thevalve installation hole152a. Acoil spring226 to press thevalve body224 downward when an external force is not applied to thevalve body224 may be installed on an outer circumferential part of thestem222.
• According to this embodiment, if the pressure inside the intermediate pressure chamber becomes higher than the discharge pressure, thebypass valve220 may apply a force greater than an elastic force of thecoil spring226 to thecoil spring226. As a result, thebypass valve220 may move upward. Accordingly, the bypass hole may open, and refrigerant inside the intermediate pressure chamber may be discharged to the discharge space.
• According to another embodiment, thecoil spring226 may not be provided. However, even if thecoil spring226 is not provided, the pressure of the discharge space may be applied to an upper surface of thevalve body224. Accordingly, in a case in which the pressure of the intermediate pressure chamber is lower than the pressure of the discharge space, thevalve body224 may cover the bypass hole. If thecoil spring226 is provided, the open valve body may move downward more rapidly, thus enhancing a response of the valve.
• FIG. 13 is a perspective view showing a bypass valve according to yet another embodiment. InFIG. 13, aplate portion243 including adischarge opening245 at a central portion thereof may be formed on an upper surface of asecond scroll240, and asuction opening244 may be formed on a side surface of thesecond scroll240. Bolt coupling holes248 may be disposed near an edge of theplate portion243, and a central portion of theplate portion243 may be concaved to form aconcaved portion243a.
• Agasket244 may be provided at a periphery of thedischarge opening245. Thegasket244 may serve to prevent leakage of a refrigerant from a space between theplate portion243 and theback pressure plate150. A pair ofprotrusions244amay be formed on an inner circumference portion of thegasket244. Theprotrusions244amay be coupled topins242 installed above theplate portion243, thereby guiding thegasket244 to be positioned at a precise position.
• The bypass valve may be installed in thegasket244, and may includevalve supporting portions224ato insert thepins242 thereinto, and aconnection portion224bthat extends between thevalve supporting portions224a. Theconnection portion224bmay have an approximate circular shape, and the valve body224cmay be formed on theconnection portion224bto open and close the bypass holes.
• According to this embodiment, if the back pressure plate and the second scroll are coupled to each other through fitting the bypass valve into the pins, the bypass valve may be coupled to the back pressure plate or the second scroll. This may facilitate the assembly process of the scroll compressor.
• Embodiments disclosed herein provide a scroll compressor and a method thereof.
• Embodiments disclosed herein a scroll compressor that may comprise a casing; a discharge cover fastened to the casing from within, the discharge cover dividing an inner space of the casing into a suction space and a discharge space; a main frame fastened to the casing from within, the main frame formed spaced apart from the discharge cover; a first or orbital scroll supported by the main frame, the orbital scroll configured to perform an orbital motion with respect to a rotational shaft of the orbital scroll in operation; a second or fixed scroll forming a suction chamber, an intermediate pressure chamber, and a discharge chamber together with the orbital scroll, the fixed scroll formed to be movable with respect to the orbital scroll and comprising a bypass hole that communicates with the intermediate pressure chamber; a back pressure chamber assembly coupled to an upper part of the fixed scroll with a fastening means or fastener, the back pressure chamber assembly being configured to press the fixed scroll toward the orbital scroll by receiving part of an operation fluid from the intermediate pressure chamber, and the back pressure chamber assembly having a discharge path that communicates the discharge chamber and the discharge space with each other; and a bypass valve that opens and closes the bypass hole, where a bypass path by which the bypass hole and the discharge path communicate with each other is formed between the back pressure chamber assembly and the fixed scroll.
• Embodiments disclosed herein provide a scroll compressor that may include a casing; a discharge cover fixed to inside of the casing, and dividing the inside of the casing into a suction space and a discharge space; a main frame spaced from the discharge cover; a first or orbital scroll which performs an orbital motion in a supported state on the main frame; a second or fixed scroll installed to be movable up and down with respect to the orbital scroll, forming a suction chamber, an intermediate pressure chamber, and a discharge chamber together with the orbital scroll, and having one or more bypass holes that communicate with the intermediate pressure chamber; a back pressure chamber assembly coupled to an upper part of the fixed scroll to restrict an upward motion of the fixed scroll, configured to press the fixed scroll toward the orbital scroll by introducing (e.g., accommodating, receiving, etc.) part of an operation fluid inside the intermediate pressure chamber, and having a discharge path to communicate the discharge chamber and the discharge space with each other; and a bypass valve to open and close the bypass hole. A bypass path to communicate the bypass hole and the discharge path with each other may be formed between the back pressure chamber assembly and the fixed scroll.
• The fixed scroll may be divided into a fixed wrap part and a back pressure chamber part, and a bypass valve and a bypass path may be disposed therebetween before the fixed wrap part and the back pressure chamber part are fastened using a fastening device. This may facilitate installation of the bypass valve, and may allow the bypass hole to be formed at an arbitrary position.
• The suction chamber, the intermediate pressure chamber, and the discharge chamber may be some of a plurality of compression chambers formed by the orbital scroll and the fixed scroll. More specifically, the suction chamber may refer to a compression chamber to which a refrigerant has been sucked to start a compression operation. The discharge chamber, which may communicate with a discharge opening, may refer to a compression chamber where a discharge has just begun or is in the process. The intermediate pressure chamber, which may be disposed between the suction chamber and the discharge chamber, may refer to a compression chamber where a compression operation is being processed or performed.
• The bypass valve may be configured to be opened and closed by a pressure difference between the intermediate pressure chamber and the discharge space. The pressure of the discharge space may mean an average pressure inside the discharge space, not a pressure of a refrigerant discharged through the fixed scroll.
• An open degree restricting means or restrictor that restricts an open degree of the bypass valve may be provided. The open degree restricting means may be formed on a lower surface of the back pressure chamber assembly, and may be provided with an additional retainer. The retainer may be formed to have a shape to optimize an open shape of the bypass valve. The retainer may be additionally provided. Alternatively, a lower surface of the back pressure chamber assembly may be implemented as the retainer.
• The bypass path may be defined by a groove portion concaved from a lower surface of the back pressure chamber assembly and an upper surface of the fixed scroll. Further, the bypass path may be defined by a groove portion concaved from an upper surface of the fixed scroll and a lower surface of the back pressure chamber assembly. The bypass valve may be configured to open and close the bypass hole while moving in the groove portion up and down. An amount of the up-and-down motion of the bypass valve may be restricted by an inner surface of the groove portion.
• The bypass valve may include a valve body configured to cover the bypass hole and a valve supporting portion or support configured to fix the valve body between the fixed scroll and the back pressure chamber assembly. A single valve supporting portion may be provided with a plurality of valve bodies. For example, the valve supporting portion may be formed to enclose the discharge opening, and the valve body may extend inward from the valve supporting portion in a radial direction. As another example, the valve supporting portion may extend in a ‘V’ shape.
• The valve supporting portion may be fixed by a coupling member that couples the back pressure assembly and the fixed scroll to each other or by an additional coupling member. In this case, the valve supporting portion may be fixed to the fixed scroll by, for example, rivets.
• A sealing means or seal to enclose the discharge path may be provided between contact surfaces of the back pressure chamber assembly and the fixed scroll.
• The back pressure chamber assembly may include a back pressure plate fixed to the fixed scroll below the discharge cover, and provided with a space portion or space an upper part of which is open, the space portion communicating with the intermediate pressure chamber; and a floating plate movably coupled to the back pressure plate so as to seal the space portion, and forming a back pressure chamber.
• The back pressure plate may include a supporting plate, which may have a ring shape and may contact an upper surface of the fixed scroll, a first ring-shaped wall formed to enclose an inner space portion of the supporting plate, and a second ring-shaped wall disposed on or at an outer circumferential part of the first ring-shaped wall. A plurality of bolt coupling holes may be formed at or in the supporting plate, and the fixed scroll and the back pressure plate may be coupled to each other by, for exmaple, bolts which pass through the bolt coupling holes.
• The floating plate may have a ring shape. The floating plate and the back pressure plate may be coupled to each other such that an outer circumferential surface of the first ring-shaped wall contacts an inner circumferential surface of the floating plate and an inner circumferential surface of the second ring-shaped wall contacts an outer circumferential surface of the floating plate. The second ring-shaped wall may be positioned on an outer circumferential surface of the supporting plate.
• A diameter of the bypass hole may be formed to be smaller than a thickness of a wrap of the fixed scroll.
• Embodiments disclosed herein further provide a scroll compressor that may include a casing divided into a suction space and a discharge space; a first or orbital scroll configured to perform an orbital motion in operation; a second or fixed scroll which forms a suction chamber, an intermediate pressure chamber, and a discharge chamber together with the orbital scroll; a bypass hole and a bypass valve configured to discharge an operation fluid to outside of the fixed scroll when pressure of the intermediate pressure chamber is higher than a discharge pressure; a discharge path that communicates with the discharge space, and a bypass path forming member configured to introduce the discharged operation fluid inside the intermediate pressure chamber to the discharge path. The discharged operation fluid inside the intermediate pressure chamber may flow between facing surfaces of the fixed scroll and the bypass path forming member, to reach the discharge path.
• Embodiments disclosed herein may have at least the following advantages.
• First, the fixed scroll may be divided into a fixed wrap part and a back pressure chamber part, and the bypass valve and the bypass path may be disposed therebetween, before the fixed wrap part and the back pressure chamber part are fastened using a fastening device. This may facilitate installation of the bypass valve.
• Further, a position of the bypass hole may be arbitrarily set, thereby minimizing occurrence of overload applied to the scroll compressor due to change in an operating condition. Further, even if the scroll compressor is overloaded at an early stage of its operation, the overload may be rapidly removed using the bypass holes and associated components.
• Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.
• Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

Claims (74)

1. A scroll compressor, comprising:

a casing;

a discharge cover, the discharge cover dividing an inner space of the casing into a suction space and a discharge space;

a main frame, the main frame being spaced apart from the discharge cover;

a first scroll supported by the main frame, the first scroll performing an orbital motion with respect to a rotational shaft thereof in operation;

a second scroll that forms a suction chamber, an intermediate pressure chamber, and a discharge chamber together with the first scroll, the second scroll being movable with respect to the first scroll and comprising a bypass hole that communicates with the intermediate pressure chamber;

a back pressure chamber assembly coupled to the second scroll, the back pressure chamber assembly comprising a back pressure plate and a floating plate and being configured to press the second scroll toward the first scroll, the back pressure chamber assembly further having a discharge path by which the discharge chamber and the discharge space with communicate with each other; and

a bypass valve that opens and closes the bypass hole, wherein a bypass path by which the bypass hole and the discharge path communicate with each other is formed between facing surfaces of the back pressure chamber assembly and the second scroll.

2. The scroll compressor ofclaim 1, wherein the back pressure plate includes a groove formed therein and the floating plate is movably disposed in the groove.

3. The scroll compressor ofclaim 2, wherein a lower surface of the back pressure plate faces an upper surface of the second scroll.

4. The scroll compressor ofclaim 3, wherein the bypass path is formed between the lower surface of the back pressure plate and the upper surface of the second scroll and extends in a lateral direction.

5. The scroll compressor ofclaim 1, wherein the bypass path includes a groove formed in one of the lower surface of the back pressure plate or the upper surface of the second scroll.

6. The scroll compressor ofclaim 1, wherein the bypass valve is opened and closed by a pressure difference between the intermediate pressure chamber and the discharge space.

7. The scroll compressor ofclaim 1, further comprising a restrictor that restricts an open degree of the bypass valve.

8. The scroll compressor ofclaim 7, wherein the restrictor is formed on a lower surface of the back pressure chamber assembly.

9. The scroll compressor ofclaim 7, wherein the restrictor comprises a retainer disposed on a lower surface of the back pressure chamber assembly.

10. The scroll compressor ofclaim 1, wherein the bypass path is defined by a groove concaved from a lower surface of the back pressure chamber assembly, and an upper surface of the second scroll, and wherein the bypass valve is configured to open and close the bypass hole via a movement within the groove.

11. The scroll compressor ofclaim 10, wherein the movement of the bypass valve is restricted by an inner surface of the groove.

12. The scroll compressor ofclaim 1, wherein the bypass path is defined by a groove concaved from an upper surface of the second scroll and a lower surface of the back pressure chamber assembly, and wherein the bypass valve is configured to open and close the bypass hole via a movement within the groove.

13. The scroll compressor ofclaim 12, wherein the movement of the bypass valve is restricted by an inner surface of the groove.

14. The scroll compressor ofclaim 1, wherein the bypass valve comprises:

a valve body configured to cover the bypass hole; and

a valve support configured to fix the valve body between the second scroll and the back pressure chamber assembly.

15. The scroll compressor ofclaim 14, wherein the valve body comprises a plurality of valve bodies.

16. The scroll compressor ofclaim 15, wherein the valve support encloses the discharge opening, and the plurality of valve bodies extend inwardly from the valve support in a radial direction.

17. The scroll compressor ofclaim 15, wherein the valve support extends in a ‘V’ shape.

18. The scroll compressor ofclaim 15, wherein the valve support is fixed by a coupling member that couples the back pressure assembly and the second scroll to each other.

19. The scroll compressor ofclaim 15, wherein the valve support is fixed to the second scroll by at least one rivet.

20. The scroll compressor ofclaim 1, further comprising a seal that encloses the discharge path disposed between contact surfaces of the back pressure chamber assembly and the second scroll.

21. The scroll compressor ofclaim 1, wherein the back pressure chamber assembly comprises:

a back pressure plate fastened to the second scroll below the discharge cover, the back pressure plate comprising a cavity with which the intermediate pressure chamber communicates; and

a floating plate movably coupled to the back pressure plate so as to seal an upper portion of the cavity.

22. The scroll compressor ofclaim 21, wherein the back pressure plate comprises:

a supporting plate having a ring shape that contacts an upper surface of the second scroll;

a first ring-shaped wall formed to enclose an inner space of the supporting plate; and

a second ring-shaped wall disposed at an outer circumference of the first ring-shaped wall.

23. The scroll compressor ofclaim 22, further comprising a plurality of bolt coupling holes formed on the supporting plate, wherein the second scroll and the back pressure plate are fastened by a corresponding number of bolts, which pass through the plurality of bolt coupling holes.

24. The scroll compressor ofclaim 22, wherein the floating plate is ring-shaped, and wherein the floating plate and the back pressure plate are coupled such that an outer circumferential surface of the first ring-shaped wall contacts an inner circumferential surface of the floating plate and an inner circumferential surface of the second ring-shaped wall contacts an outer circumferential surface of the floating plate.

25. The scroll compressor ofclaim 22, wherein the second ring-shaped wall is positioned at an outer circumferential surface of the supporting plate.

26. The scroll compressor ofclaim 1, wherein a diameter of the bypass hole is formed to be smaller than a thickness of a wrap of the second scroll.

27. A scroll compressor, comprising:

a casing comprising a suction space and a discharge space;

a first scroll that forms a suction chamber, an intermediate pressure chamber, and a discharge chamber together with a second scroll;

a bypass hole and a bypass valve configured to discharge an operation fluid outside of the second scroll when pressure of the intermediate pressure chamber is higher than a discharge pressure;

a discharge path that communicates with the discharge space; and

a back pressure plate configured to introduce the discharged operation fluid to the discharge path, wherein the discharged operation fluid flows between facing surfaces of the second scroll and the back pressure plate, to thus reach the discharge path.

28. The scroll compressor ofclaim 27, wherein the back pressure plate includes a groove formed therein and the floating plate is movably disposed in the groove.

29. The scroll compressor ofclaim 28, wherein a lower surface of the back pressure plate faces an upper surface of the second scroll.

30. The scroll compressor ofclaim 29, wherein a bypass path is formed between the lower surface of the back pressure plate and the upper surface of the second scroll and extends in a lateral direction.

31. The scroll compressor ofclaim 27, wherein the discharged operation fluid flows along a groove formed in one of a lower surface of the back pressure plate or an upper surface of the second scroll, to thus reach the discharge path

32. The scroll compressor ofclaim 27, further comprising a restrictor that restricts an open degree of the bypass valve.

33. The scroll compressor ofclaim 32, wherein the restrictor is formed on a lower surface of the back pressure plate.

34. The scroll compressor ofclaim 33, wherein the restrictor comprises a retainer disposed on a lower surface of the back pressure plate.

35. The scroll compressor ofclaim 27, wherein a bypass path is defined by a groove concaved from a lower surface of the back pressure plate, and an upper surface of the second scroll, and wherein the bypass valve is configured to open and close the bypass hole via a movement within the groove.

36. The scroll compressor ofclaim 35, wherein the movement of the bypass valve is restricted by an inner surface of the groove.

37. The scroll compressor ofclaim 27, wherein a bypass path is defined by a groove concaved from an upper surface of the second scroll and a lower surface of the back pressure plate, and wherein the bypass valve is configured to open and close the bypass hole via a movement within the groove.

38. The scroll compressor ofclaim 37, wherein the movement of the bypass valve is restricted by an inner surface of the groove.

39. The scroll compressor ofclaim 27, wherein the bypass valve comprises:

a valve body configured to cover the bypass hole; and

a valve support configured to fix the valve body between the second scroll and the back pressure plate.

40. The scroll compressor ofclaim 39, wherein the valve body comprises a plurality of valve bodies.

41. The scroll compressor ofclaim 40, wherein the valve support encloses the discharge opening, and the plurality of valve bodies extend inwardly from the valve support in a radial direction.

42. The scroll compressor ofclaim 40, wherein the valve support extends in a ‘V’ shape.

43. The scroll compressor ofclaim 40, wherein the valve support is fixed by a coupling member that couples the back pressure plate and the second scroll to each other.

44. The scroll compressor ofclaim 40, wherein the valve support is fixed to the second scroll by at least one rivet.

45. The scroll compressor ofclaim 27, further comprising a seal that encloses the discharge path disposed between contact surfaces of the back pressure plate and the second scroll.

46. The scroll compressor ofclaim 27, wherein the back pressure plate comprises:

a supporting plate having a ring shape that contacts an upper surface of the second scroll;

a first ring-shaped wall formed to enclose an inner space of the supporting plate; and

a second ring-shaped wall disposed at an outer circumference of the first ring-shaped wall.

47. The scroll compressor ofclaim 46, further comprising a plurality of bolt coupling holes formed on the supporting plate, wherein the second scroll and the back pressure plate are fastened by a corresponding number of bolts, which pass through the plurality of bolt coupling holes.

48. The scroll compressor ofclaim 46, further comprising a ring-shaped floating plate, wherein the floating plate and the back pressure plate are coupled such that an outer circumferential surface of the first ring-shaped wall contacts an inner circumferential surface of the floating plate and an inner circumferential surface of the second ring-shaped wall contacts an outer circumferential surface of the floating plate.

49. The scroll compressor ofclaim 46, wherein the second ring-shaped wall is positioned at an outer circumferential surface of the supporting plate.

50. The scroll compressor ofclaim 27, wherein a diameter of the bypass hole is formed to be smaller than a thickness of a wrap of the second scroll.

51. A scroll compressor, comprising:

a casing;

a discharge cover, the discharge cover dividing an inner space of the casing into a suction space and a discharge space;

a main frame, the main frame being spaced apart from the discharge cover;

a first scroll supported by the main frame, the first scroll performing an orbital motion with respect to a rotational shaft thereof in operation;

a second scroll that forms a suction chamber, an intermediate pressure chamber, and a discharge chamber together with the first scroll, the second scroll being movable with respect to the first scroll and comprising a bypass hole that communicates with the intermediate pressure chamber;

a back pressure chamber assembly coupled to the second scroll, the back pressure chamber assembly comprising a back pressure plate and a floating plate and being configured to press the second scroll toward the first scroll, the back pressure chamber assembly further having a discharge path by which the discharge chamber and the discharge space with communicate with each other; and

a bypass valve that opens and closes the bypass hole, wherein the back pressure plate comprises a back pressure cavity formed by inner and outer circumferential walls, and wherein the bypass hole is formed in the second scroll at a position outwardly spaced from the inner circumferential wall in a radial direction.

52. The scroll compressor ofclaim 51, wherein a lower surface of the back pressure plate faces an upper surface of the second scroll.

53. The scroll compressor ofclaim 52, wherein a bypass path is formed between the lower surface of the back pressure plate and the upper surface of the second scroll and extends in a lateral direction.

54. The scroll compressor ofclaim 53, wherein the bypass path includes a groove formed in one of the lower surface of the back pressure plate or the upper surface of the second scroll.

55. The scroll compressor ofclaim 51, wherein the bypass valve is opened and closed by a pressure difference between the intermediate pressure chamber and the discharge space.

56. The scroll compressor ofclaim 51, further comprising a restrictor that restricts an open degree of the bypass valve.

57. The scroll compressor ofclaim 56, wherein the restrictor is formed on a lower surface of the back pressure chamber assembly.

58. The scroll compressor ofclaim 56, wherein the restrictor comprises a retainer disposed on a lower surface of the back pressure chamber assembly.

59. The scroll compressor ofclaim 51, wherein a bypass path is defined by a groove concaved from a lower surface of the back pressure plate, and an upper surface of the second scroll, and wherein the bypass valve is configured to open and close the bypass hole via a movement within the groove.

60. The scroll compressor ofclaim 59, wherein the movement of the bypass valve is restricted by an inner surface of the groove.

61. The scroll compressor ofclaim 51, wherein a bypass path is defined by a groove concaved from an upper surface of the second scroll and a lower surface of the back pressure plate, and wherein the bypass valve is configured to open and close the bypass hole via a movement within the groove.

62. The scroll compressor ofclaim 61, wherein the movement of the bypass valve is restricted by an inner surface of the groove.

63. The scroll compressor ofclaim 51, wherein the bypass valve comprises:

a valve body configured to cover the bypass hole; and

a valve support configured to fix the valve body between the second scroll and the back pressure plate.

64. The scroll compressor ofclaim 63, wherein the valve body comprises a plurality of valve bodies.

65. The scroll compressor ofclaim 64, wherein the valve support encloses the discharge opening, and the plurality of valve bodies extend inwardly from the valve support in a radial direction.

66. The scroll compressor ofclaim 64, wherein the valve support extends in a ‘V’ shape.

67. The scroll compressor ofclaim 64, wherein the valve support is fixed by a coupling member that couples the back pressure plate and the second scroll to each other.

68. The scroll compressor ofclaim 64, wherein the valve support is fixed to the second scroll by at least one rivet.

69. The scroll compressor ofclaim 51, further comprising a seal that encloses the discharge path disposed between contact surfaces of the back pressure plate and the second scroll.

70. The scroll compressor ofclaim 51, wherein the back pressure plate comprises:

a supporting plate having a ring shape that contacts an upper surface of the second scroll;

a first ring-shaped wall formed to enclose an inner space of the supporting plate; and

a second ring-shaped wall disposed at an outer circumference of the first ring-shaped wall.

71. The scroll compressor ofclaim 70, further comprising a plurality of bolt coupling holes formed on the supporting plate, wherein the second scroll and the back pressure plate are fastened by a corresponding number of bolts, which pass through the plurality of bolt coupling holes.

72. The scroll compressor ofclaim 70, wherein the floating plate is ring-shaped, and wherein the floating plate and the back pressure plate are coupled such that an outer circumferential surface of the first ring-shaped wall contacts an inner circumferential surface of the floating plate and an inner circumferential surface of the second ring-shaped wall contacts an outer circumferential surface of the floating plate.

73. The scroll compressor ofclaim 70, wherein the second ring-shaped wall is positioned at an outer circumferential surface of the supporting plate.

74. The scroll compressor ofclaim 51, wherein a diameter of the bypass hole is formed to be smaller than a thickness of a wrap of the second scroll.

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