Patent Grant
9689386
This invention generally relates to multi-compressor refrigeration systems.
A particular example of the state of the art with respect to suction gas distribution in a parallel compressor assembly is represented by WIPO patent publication WO2008/081093 (Device For Suction Gas Distribution In A Parallel Compressor Assembly, And Parallel Compressor Assembly), which shows a distribution device for suction gas in systems with two or more compressors, the teachings and disclosure of which is incorporated in its entirety herein by reference thereto. A particular example of oil management in systems having multiple compressors is disclosed in U.S. Pat. No. 4,729,228 (Suction Line Flow Stream Separator For Parallel Compressor Arrangements), the teachings and disclosure of which is incorporated in its entirety herein by reference thereto.
Embodiments of the invention described herein represent an advancement over the current state of the art. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
In one aspect, embodiments of the invention provide a method of operating a refrigeration system uses a plurality of compressors connected in parallel. The method includes returning refrigerant to the compressors, the refrigerant having oil entrained therein, separating the oil from the refrigerant, and returning more of the oil to a lead compressor of the plurality of compressors regardless of whether the lead compressor is operating. The method also includes connecting the oil sumps of all of the plurality of compressors such that oil is supplied from the lead compressor to at least one non-lead compressor of the plurality of compressors when the at least one non-lead compressor is operating.
Further, the method may include providing a suction header, also referred to as a common supply line, configured to supply more oil to the lead compressor than is supplied to the non-lead compressors. An embodiment of the method further includes providing, to an inlet port for each of the plurality of compressors, a separate inlet supply line, wherein configuring the common supply line to supply more oil to the lead compressor comprises restricting the inlet supply lines to each of the non-lead compressors. Also, the restriction of the inlet supply lines may be designed to create reduced suction pressures at the inlet ports of the non-lead compressors, as compared to the suction pressure at the inlet port of the lead compressor. In certain embodiments, each of the compressors discharges refrigerant and oil to a common outlet line.
In certain embodiments, the method includes constructing a refrigeration system by connecting a plurality of scroll compressors in parallel. A further embodiment of the method includes locating each pipe connection at the same horizontal level or oil sump level. Moreover, in particular embodiments, the method includes locating each pipe connection so that oil will flow out through the pipe connection from the lead compressor, whether or not the lead compressor is operating, to at least one of the non-lead compressors, which is operating. This flow will continue until the oil sump pressures in the oil sumps of the lead compressor and the at least one of the non-lead compressors are approximately the same.
In a particular embodiment, the method includes connecting the oil sumps of all of the plurality of compressors such that oil does not flow from the lead compressor to a non-lead compressor of the plurality of compressors when the non-lead compressor is not operating. In this case, the oil does not flow to the non-operating non-lead compressor due to a rise in oil sump pressure in that non-operating non-lead compressor
In another aspect, embodiments of the invention provide a refrigeration system that includes a plurality of compressors connected in parallel. The plurality of compressors includes at least one lead compressor, and each compressor has a compressor housing. There is a common supply line for supplying refrigerant and oil to each of the plurality of compressors. The common supply line is configured to return more oil to the lead compressor than to the non-lead compressors of the plurality of compressors. Each compressor has an opening in a lower portion of its respective compressor housing, and each opening is configured to allow a flow of oil to and from an oil sump for its respective compressor. Further, each opening is coupled to a pipe so that the oil sumps for each of the plurality of compressors are in fluid communication. Also, each opening is located such that the oil can be distributed from the lead compressor to any of the non-lead compressors of the plurality of compressors whether or not the lead compressor is operating.
In a particular embodiment of the invention, the lead compressor, whether or not it is operating, distributes oil to any of the non-lead compressors of the plurality of compressors that are operating. In certain embodiments, each of the plurality of compressors has an inlet supply line coupled to the common supply line, and the inlet supply line for any of the plurality of compressors, other than the lead compressor, has a restriction to reduce the flow of oil into the compressor. In particular embodiments, the restriction in the inlet supply line is configured to create reduced suction pressure at the inlet port of its respective compressor.
Further, it is contemplated that embodiments of the invention include multi-compressor systems in which the individual compressors have different capacities. The use of a plurality of compressors in a refrigeration system, where the individual compressors have different volume indexes is disclosed in U.S. Patent Publication No. 2010/0186433 (Scroll Compressors With Different Volume Indexes and Systems and Methods For Same), filed on Jan. 22, 2010, the teachings and disclosure of which is incorporated in its entirety herein by reference thereto.
In yet another aspect, embodiments of the invention provide a refrigeration system that includes a plurality of compressors connected in parallel. The plurality of compressors includes at least one lead compressor, and each compressor has a compressor housing. There is a supply line for supplying refrigerant and oil to the at least one lead compressor, from which the refrigerant and oil is supplied to remaining compressors of the plurality of compressors. Each compressor has an opening in a lower portion of its respective compressor housing, and each opening is configured to allow a flow of oil to and from an oil sump for its respective compressor. Further, each opening is coupled to a pipe so that the oil sumps for each of the plurality of compressors are in fluid communication. Also, each opening is located such that the oil can be distributed from the lead compressor to any of the remaining compressors of the plurality of compressors whether or not the lead compressor is operating. In a particular embodiment, the lead compressor has a vertical header connected to the supply line, the vertical header arranged to drain oil into the oil sump in the lead compressor.
Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
The following detailed description describes embodiments of the invention as applied in a multi-compressor refrigeration system. However, one of ordinary skill in the art will recognize that the invention is not necessarily limited to refrigeration systems. Embodiments of the invention may also find use in other systems where multiple compressors are used to supply a flow of compressed gas.
An evaporation unit 11 to provide cooling is also arranged in fluid series downstream of the condenser 7. In an alternate embodiment, the condenser 7 may feed multiple evaporation units arranged in parallel. In the embodiment of
It should be noted that, for the sake of convenience, embodiments of the invention are frequently described hereinbelow with respect to their application in systems having multiple scroll compressors for compressing refrigerant. While particular advantages and configurations are shown for scroll compressor, some of these embodiments are not limited to scroll compressors, but may find use in a variety of compressors other than scroll compressors.
An embodiment of the present invention is illustrated in
The outer housing 12 may take various forms. In a particular embodiment, the outer housing 12 includes multiple housing or shell sections, and, in certain embodiments, the outer housing 12 has three shell sections that include a central housing section 24, a top end housing section 26 and a bottom end housing section, or base plate 28. In particular embodiments, the housing sections 24, 26, 28 are formed of appropriate sheet steel and welded together to make a permanent outer housing 12 enclosure. However, if disassembly of the outer housing 12 is desired, methods for attaching the housing sections 24, 26, 28 other than welding may be employed including, but not limited to, brazing, use of threaded fasteners or other suitable mechanical means for attaching sections of the outer housing 12.
The central housing section 24 is preferably tubular or cylindrical and may abut or telescopically fit with the top and bottom end housing sections 26, 28. As can be seen in the embodiments of
In an exemplary embodiment of the invention in which a scroll compressor 14 is disposed within the outer housing 12, the scroll compressor 14 includes first and second scroll compressor bodies which preferably include a stationary fixed scroll compressor body 110 and a movable scroll compressor body 112. While the term “fixed” generally means stationary or immovable in the context of this application, more specifically “fixed” refers to the non-orbiting, non-driven scroll member, as it is acknowledged that some limited range of axial, radial, and rotational movement is possible due to thermal expansion and/or design tolerances.
The movable scroll compressor body 112 is arranged for orbital movement relative to the fixed scroll compressor body 110 for the purpose of compressing refrigerant. The fixed scroll compressor body includes a first rib 114 projecting axially from a plate-like base 116 which is typically arranged in the form of a spiral. Similarly, the movable scroll compressor body 112 includes a second scroll rib 118 projecting axially from a plate-like base 120 and is in the shape of a similar spiral. The scroll ribs 114, 118 engage with one another and abut sealingly on the respective surfaces of bases 120, 116 of the respectively other compressor body 112, 110.
In a particular embodiment of the invention, the drive unit 16 in is the form of an electrical motor assembly 40. The electrical motor assembly 40 operably rotates and drives a shaft 46. Further, the electrical motor assembly 40 generally includes a stator 50 comprising electrical coils and a rotor 52 that is coupled to the drive shaft 46 for rotation together. The stator 50 is supported by the outer housing 12, either directly or via an adapter. The stator 50 may be press-fit directly into outer housing 12, or may be fitted with an adapter (not shown) and press-fit into the outer housing 12. In a particular embodiment, the rotor 52 is mounted on the drive shaft 46, which is supported by upper and lower bearing members 42, 44.
Energizing the stator 50 is operative to rotatably drive the rotor 52 and thereby rotate the drive shaft 46 about a central axis 54. Applicant notes that when the terms “axial” and “radial” are used herein to describe features of components or assemblies, they are defined with respect to the central axis 54. Specifically, the term “axial” or “axially-extending” refers to a feature that projects or extends in a direction along, or parallel to, the central axis 54, while the terms “radial’ or “radially-extending” indicates a feature that projects or extends in a direction perpendicular to the central axis 54.
In particular embodiments, the lower bearing member 44 includes a central, generally cylindrical hub 58 that includes a central bushing and opening to provide a cylindrical bearing 60 to which the drive shaft 46 is journaled for rotational support. A plate-like ledge region 68 of the lower bearing member 44 projects radially outward from the central hub 58, and serves to separate a lower portion of the stator 50 from an oil lubricant sump 76. An axially-extending perimeter surface 70 of the lower bearing member 44 may engage with the inner diameter surface of the central housing section 24 to centrally locate the lower bearing member 44 and thereby maintain its position relative to the central axis 54. This can be by way of an interference and press-fit support arrangement between the lower bearing member 44 and the outer housing 12.
As can be seen in the embodiment of
At its upper end, the drive shaft 46 is journaled for rotation within the upper bearing member 42. Hereinafter, the upper bearing member 42 is also referred to as a “crankcase”. In particular embodiments, the drive shaft 46 further includes an offset eccentric drive section 74 which typically has a cylindrical drive surface about an offset axis that is offset relative to the central axis 54. This offset drive section 74 may be journaled within a central hub 128 of the movable scroll compressor body 112 of the scroll compressor 14 to drive the movable scroll compressor body 112 about an orbital path when the drive shaft 46 rotates about the central axis 54. To provide for lubrication of all of the various bearing surfaces, the outer housing 12 provides the oil lubricant sump 76 at the bottom end of the outer housing 12 in which a suitable amount of oil lubricant may be stored.
It can also be seen that
Additionally, in particular embodiments, the suction duct 300 includes a screen 308 in the opening 304 that filters refrigerant gas as it enters the compressor through the inlet port 18, as illustrated in
As shown in
During operation, the refrigerant gas flowing into the inlet port 18 is cooler than compressed refrigerant gas at the outlet port 20. Further, during operation of the scroll compressor 14, the temperature of the motor 40 will rise. Therefore, it is desirable to cool the motor 40 during operation of the compressor. To accomplish this, cool refrigerant gas that is drawn into the compressor outer housing 12 via inlet port 18 flows upward through and along the motor 40 in order to reach the scroll compressor 14, thereby cooling the motor 40.
Furthermore, the impeller tube 47 and inlet port 78 act as an oil pump when the drive shaft 46 is rotated, and thereby pumps oil out of the lubricant sump 76 into an internal lubricant passageway 80 defined within the drive shaft 46. During rotation of the drive shaft 46, centrifugal force acts to drive lubricant oil up through the lubricant passageway 80 against the action of gravity. The lubricant passageway 80 has various radial passages projecting therefrom to feed oil through centrifugal force to appropriate bearing surfaces and thereby lubricate sliding surfaces as may be required.
A duct channel provides a fluid flow path to a drain port 330 at or near the bottom end 326 of the suction duct 234. In this embodiment, the drain port 330 extends through the bottom end 326 and thereby provides a port for draining lubricant oil into the lubricant oil sump 76, and also to communicate substantially the entire flow of refrigerant for compression to a location just upstream of the motor housing.
Not only does the suction duct 234 act to direct substantially the entire flow of refrigerant and oil from the inlet port 18 to a location upstream of the motor 40 and to direct fluid flow through the motor 40, but it also acts as a gravitational drain preferably by the port 330 being at the absolute gravitational bottom of the suction duct 234 or proximate thereto so as to drain lubricant received in the suction duct 234 into the lubricant oil sump 76. This can be advantageous for several reasons. First, when it is desirable to fill the lubricant oil sump 76 either at initial charting or otherwise, oil can readily be added through the inlet port 18, which acts also as an oil fill port so that oil will naturally drain through the suction duct 234 and into the oil sump 76 through the drain port 330. The outer housing 12 can thereby be free of a separate oil port. Additionally, the surfaces of the suction duct 234 and redirection of oil therein causes coalescing of oil lubricant mist, which can then collect within the duct channel 322 and drain through the drain port 330 back into the oil sump 76. Thus, direction of refrigerant as well as direction of lubricant oil is achieved with the suction duct 234.
During operation, the scroll compressor assemblies 10 are operable to receive low pressure refrigerant at the housing inlet port 18 and compress the refrigerant for delivery to a high pressure chamber 180 where it can be output through the housing outlet port 20. As is shown, in
Upon passing through the upper bearing member 42, the low pressure refrigerant finally enters an intake area 124 of the scroll compressor bodies 110, 112. From the intake area 124, the lower pressure refrigerant is progressively compressed through chambers 122 to where it reaches its maximum compressed state at a compression outlet 126 where it subsequently passes through a check valve and into the high pressure chamber 180. From there, high-pressure compressed refrigerant may then pass from the scroll compressor assembly 10 through the outlet port 20.
With respect to compressors #1, #2, and #3 202, the internal flow of refrigerant through the compressors 202 with their isolated oil sumps 76 configuration creates a pressure drop from the suction inlet port 18 to the oil sump 76 in each of the compressors that are running, due to the restriction of the gas flow. When any of these compressors 202 is shut off and there is no flow restriction, the oil sump 76 pressure will be relatively higher than a running compressor with the same suction inlet pressure. This pressure differential between the oil sump 76 of a running compressor and the oil sump 76 of an off compressor allows for oil distribution from the off compressor to the running compressors in the refrigeration system 200, 220.
In the arrangements shown in
Another embodiment of the invention is shown in
Referring again to
In the embodiments shown in
The combination of providing more oil to the lead compressor #2 202 and configuring the piping to create reduced pressure at the suction inlet port 18 in the non-lead compressors #1 and #3 202 will result in sufficient oil distribution to all of the compressors #1, #2, and #3 202 in this multiple-compressor arrangement, regardless of whether any individual compressor is on or off. Moreover, in particular embodiments, this flow of oil from the lead compressor #2 202 will continue until equalization of the pressures in the compressor #2 202 and in the non-lead compressors receiving the flow of oil. This is shown in the operating matrix below in Table 1.
The above-shown matrix (Table 1) indicates how oil is distributed in the refrigeration systems of
All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
This patent application claims the benefit of U.S. Provisional Patent Application Nos. 61/677,742, filed Jul. 31, 2012, 61/677,756, filed Jul. 31, 2012, and 61/793,988 filed Mar. 15, 2013, the entire teachings and disclosures of which are incorporated herein by reference thereto.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3360958 | Miner | Jan 1968 | A |
| 3386262 | Hackbart et al. | Jun 1968 | A |
| 3581519 | Garrett, Jr. et al. | Jun 1971 | A |
| 4729228 | Johnsen | Mar 1988 | A |
| 5901559 | Westermeyer et al. | May 1999 | A |
| 6599109 | Zamudio et al. | Jul 2003 | B2 |
| 6736607 | Ginies et al. | May 2004 | B2 |
| 7316291 | Thomsen et al. | Jan 2008 | B2 |
| 7421850 | Street et al. | Sep 2008 | B2 |
| 7721757 | Ginies et al. | May 2010 | B2 |
| 8079830 | Süss et al. | Dec 2011 | B2 |
| 8337183 | Milliff et al. | Dec 2012 | B2 |
| 20010026766 | Terai et al. | Oct 2001 | A1 |
| 20050229627 | De Bernardi et al. | Oct 2005 | A1 |
| 20060059929 | Sakitani et al. | Mar 2006 | A1 |
| 20070074534 | Sato | Apr 2007 | A1 |
| 20090035168 | Ginies et al. | Feb 2009 | A1 |
| 20090041602 | Ginies et al. | Feb 2009 | A1 |
| 20090081062 | Upadhye et al. | Mar 2009 | A1 |
| 20100186433 | Galante et al. | Jul 2010 | A1 |
| 20100186439 | Ogata et al. | Jul 2010 | A1 |
| 20120017636 | Wada et al. | Jan 2012 | A1 |
| Number | Date | Country |
|---|---|---|
| 1318145 | Oct 2001 | CN |
| 1985091 | Jun 2007 | CN |
| 101999064 | Mar 2011 | CN |
| 1 120 611 | Aug 2001 | EP |
| 04287880 | Oct 1992 | JP |
| 05071811 | Mar 1993 | JP |
| H05272477 | Oct 1993 | JP |
| 07035045 | Feb 1995 | JP |
| H0829018 | Feb 1996 | JP |
| H0861809 | Mar 1996 | JP |
| 08128764 | May 1996 | JP |
| 2605498 | Apr 1997 | JP |
| 2001132645 | May 2001 | JP |
| 2005076515 | Mar 2005 | JP |
| 1020050065258 | Jun 2005 | KR |
| WO 9716647 | May 1997 | WO |
| WO 2005103492 | Nov 2005 | WO |
| WO 2008081093 | Jul 2008 | WO |
| Entry |
|---|
| U.S. Appl. No. 13/950,488, filed Jul. 25, 2013, Fraser et al. |
| U.S. Appl. No. 13/932,540, filed Jul. 1, 2013, Fraser et al. |
| Number | Date | Country | |
|---|---|---|---|
| 20140037483 A1 | Feb 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61677742 | Jul 2012 | US | |
| 61677756 | Jul 2012 | US | |
| 61793988 | Mar 2013 | US |
