US20010031213A1 - Screw machine - Google Patents
Screw machine Download PDFInfo
- Publication number
- US20010031213A1 US20010031213A1 US09/742,978 US74297800A US2001031213A1 US 20010031213 A1 US20010031213 A1 US 20010031213A1 US 74297800 A US74297800 A US 74297800A US 2001031213 A1 US2001031213 A1 US 2001031213A1
- Authority
- US
- United States
- Prior art keywords
- rotor
- rotors
- end faces
- screw machine
- depressions
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
- F01C1/00—Rotary-piston machines or engines
- F01C1/08—Rotary-piston machines or engines of intermeshing engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing
- F01C1/12—Rotary-piston machines or engines of intermeshing engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing of other than internal-axis type
- F01C1/14—Rotary-piston machines or engines of intermeshing engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
- F01C1/16—Rotary-piston machines or engines of intermeshing engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with helical teeth, e.g. chevron-shaped, screw type
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
- F01C1/00—Rotary-piston machines or engines
- F01C1/08—Rotary-piston machines or engines of intermeshing engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing
- F01C1/082—Details specially related to intermeshing engagement type machines or engines
- F01C1/084—Toothed wheels
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
- F01C19/00—Sealing arrangements in rotary-piston machines or engines
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
- F01C19/00—Sealing arrangements in rotary-piston machines or engines
- F01C19/08—Axially-movable sealings for working fluids
- F01C19/085—Elements specially adapted for sealing of the lateral faces of intermeshing-engagement type machines or engines, e.g. gear machines or engines
Definitions
- a male rotor and a female rotor disposed in respective parallel overlapping bores defined within a rotor housing, coact to trap and compress volumes of gas. While such two rotor configurations are the most common design, screw machines are also known in the art having three, or more, rotors housed in respective overlapping bores so as to coact in pairs. Paired male and female rotors differ in their lobe profiles and in the number of lobes and flutes. For example, the female rotor may have six lobes separated by six flutes, while the conjugate male rotor may have five lobes separated by five flutes. Accordingly, each possible combination of lobe and flute coaction between the rotors occurs on a cyclic basis.
- the interface surface area between the rotor end faces and the end casing is reduced by reason of a reduction in the surface area of at least either the rotor end faces or the facing surface of the outlet casing.
- discrete, non-interconnected, relatively large depressions are formed in the rotor end faces.
- the rotor end faces may have a textured surface providing a multiplicity of interconnected, relatively small depressions.
- the surface of the outlet casing facing the rotor end faces is textured or otherwise provided with depressions.
- FIG. 1 is a transverse section through a screw machine
- FIG. 2 is a partially sectioned view of the screw machine of FIG. 1;
- FIG. 3 is an enlarged view of a portion of the discharge end of the screw machine of FIG. 1;
- FIG. 4 is an end view of the rotors taken along line 4 - 4 of FIG. 3 showing one embodiment of the end faces of the rotors;
- FIG. 5 is an end view of the rotors showing an alternate embodiment of the end faces of the rotors:
- FIG. 6 is an end view of the rotors showing a further alternate embodiment of the end faces of the rotors.
- a screw machine 10 such as a screw compressor, having a rotor housing or casing 12 with a pair of overlapping bores 13 and 15 located therein.
- Female rotor 14 is located in bore 13 and male rotor 16 is located in bore 15 .
- the bores 13 and 15 generally extend along parallel axes, A and B, respectively.
- female rotor 14 has six lobes 14 A separated by six flutes, while male rotor 16 has five lobes separated by five flutes. Accordingly, the rotational speed of rotor 16 will be 6/5 or 120% of that of rotor 14 .
- Either the female rotor 14 or the male rotor 16 may be connected to a prime mover (not illustrated) and serve as the driving rotor. Other combinations of the number of female and male lands and grooves may also be used.
- rotor 14 has a shaft portion 23 with an end face 24 formed on the end of the rotor 14 radially outward of the shaft portion 23 .
- Shaft portion 23 of rotor 14 is supported in outlet or discharge casing 53 by one, or more, bearing(s) 30 .
- rotor 16 has a shaft portion 25 with an end face 26 formed on the end of the rotor 16 radially outward of the shaft portion 26 .
- Shaft portion 25 of rotor 16 is supported in outlet casing 53 by one, or more bearing(s) 31 .
- Suction side shaft portions 27 and 29 of rotors 14 and 16 are supportingly received in rotor housing 12 by roller bearings 32 and 33 , respectively.
- This end running clearance 60 is defined as the region between the closest interface surfaces of the rotor end faces 24 and 26 and the facing surface 51 of the end plate 55 .
- This end running clearance 60 establishes a potential gas leakage path, both circumferential and radial, between rotor end faces 24 and 26 and the end plate 55 of the outlet casing 53 .
- lubrication oil that naturally flows into the end-running clearance 60 serves as a seal to reduce gas leakage through the end-running clearance.
- the interface surface area defining the end running clearance 60 between the rotor end faces 24 and 26 and the facing surface 51 of the end plate 55 of the outlet casing 53 is reduced by removing material from the rotor end faces 24 and 26 or the facing surface 51 of the end plate 55 .
- the friction losses caused by viscous forces due to the oil in the region between the rotor end faces 24 and 26 of the respective rotors and the facing surface 51 of the end plate 51 of the outlet casing 53 is reduced.
- depressions 44 , 44 A and 46 , 46 A are formed in the rotor end faces 24 and 26 , respectively.
- Depression 44 is provided in the central region of the end face 24 of the female rotor 14 to extend about the shaft 23 and depressions 44 A are formed in the lobes 14 A.
- depression 46 is provided in the central region of the end face 26 of the male rotor 16 to extend about the shaft 25 and depressions 46 A are formed in the lobes 16 A.
- the shoulders 45 separate the respective depressions 44 and 44 A in the rotor end face 24 and the shoulders 47 separate the respective depressions 46 and 46 A in the rotor end face 26 .
- the depressions 44 , 44 A, 46 and 46 A comprise discrete, unconnected depressions and the interface surface area is reduced to the surface area of the shoulders 45 and 47 .
- the depth of the depressions 44 , 44 A, 46 and 46 A although not critical to the invention, advantageously lies in the range from about 0.002 inch to about 0.50 inch.
- discrete depressions 54 and 56 are formed in the rotor end faces 24 and 26 , respectively, in a petal-like pattern.
- each of the plurality of depressions 54 and 56 are discrete, unconnected depressions separated by shoulder portions 55 and 57 , respectively, and the interface surface area is reduced to the surface area of the shoulder portions.
- the depth of the depressions 54 and 56 although not critical to the invention, again advantageously lies in the range from about 0.002 inch to about 0.50 inch.
- each of the rotor end faces 24 and 26 comprises a textured surface having a plurality of small depressions 64 formed between rises 66 and dispersed extensively across substantially the entire surface of the rotor end faces.
- the interface surface area is reduced to the surface area of the rises rather than the surface area of the overall rotor end face.
- the depth of the depressions 64 are not critical to the invention, but advantageously have a depth in the range from about 0.001 inch to about 0.20 inch.
- the interface area between the rotor end faces 24 and 26 and the facing surface 51 of the outlet casing 53 may be reduced in accordance with the present invention by providing depressions in or a textured surface on the facing surface 51 .
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Applications Or Details Of Rotary Compressors (AREA)
Abstract
A screw machine (10) has a rotor housing (12) defining overlapping bores (13, 15). Female rotor (14) is located in bore (13) and male rotor (16) is located in bore (15). The end faces (24, 26) of the female and male rotors, respectively, have depressions (44, 46, 54, 56, 64) formed in their surface whereby the interface area with the facing surface (51) of the outlet casing (53) is reduced.
Description
- This application claims benefit of U.S. provisional application Ser. No. 60/172,767, filed on Dec. 20, 1999.
- In a conventional screw machine, a male rotor and a female rotor, disposed in respective parallel overlapping bores defined within a rotor housing, coact to trap and compress volumes of gas. While such two rotor configurations are the most common design, screw machines are also known in the art having three, or more, rotors housed in respective overlapping bores so as to coact in pairs. Paired male and female rotors differ in their lobe profiles and in the number of lobes and flutes. For example, the female rotor may have six lobes separated by six flutes, while the conjugate male rotor may have five lobes separated by five flutes. Accordingly, each possible combination of lobe and flute coaction between the rotors occurs on a cyclic basis.
- The rotors of a typical screw machine are mounted in bearings at each end so as to provide both radial and axial restraint. Nevertheless, in conventional practice, a certain amount of clearance in the axial direction must be provided between the end face of the rotors and the facing surface of the housing. The need to provide an end running clearance is primarily the result of thermal growth of the rotors as a result of gas being heated in the compression process. Maintaining the desired end running clearance at an amount sufficient to ensure that contact does not occur between the end face of the rotors and the facing surface of the housing is important to reliable operation of the screw machine. Additionally, during operation, the pressure gradient in the fluid being compressed normally acts on the rotors in an axial direction tending to force the rotors toward the suction end of the screw machine, thereby tending to increase the end running clearance.
- If the end running clearance is too large, excessive circumferential and radial leakage of compressed fluid may occur through the running clearance at the discharge end of the screw machine thereby significantly decreasing the overall efficiency of the screw machine. In conventional oil-flooded screw machines, it is customary to supply oil to the interface zone defined by the end running clearance between the rotor end faces and the housing end plate as a means of providing a fluid seal to reduce gas leakage through the interface zone. However, as the end running clearance is reduced, efficiency losses due to viscous friction forces in the oil between the rotor end faces and the housing end plate tend to increase.
- As noted previously, in operation the rotors grow in the axial direction toward the end casing at the discharge end of the housing due to thermal growth resulting from the fluid being heated in the compression process. This thermal growth of the rotors tends to reduce the end-running clearance. However, during operation the aforenoted axial pressure gradient tends to push the rotors in an axial direction towards the suction end of the screw machine, thereby tending to increase the end running clearance.
- Therefore, in conventional oil-flooded screw machines, it is customary to maintain a substantial amount of end running clearance to minimize friction losses and, in the extreme, to prevent failure from rotor seizure. Such seizure may result by the thermal growth of the rotor due to the compression process augmented by thermal growth from heat generated by the aforementioned friction forces. As the end running clearance decreases, these viscous friction forces increase and may generate sufficient additional heat to cause further thermal growth, leading to further reduction in the end-running clearance.
- As noted previously, the penalty for maintaining a large end running clearance is a consequent increase in leakage of compressed fluid. In order to maintain a large end running clearance in conventional oil-flooded screw compressors, it is known to add material to the end face of the rotors to provide a physical barrier to circumferential gas leakage. For example, elongated bar strips have been welded to rotor end faces so as to extend radially along the centerline of the lobes or lands of the rotors thereby extending across and bridging a substantial portion of the end-running clearance.
- It is an object of this invention to improve operating efficiency in a screw machine.
- It is another object of this invention to reduce rotor end leakage in a screw machine.
- It is a further object of this invention to reduce frictional losses, without increasing leakage, between the rotor end faces and the housing end plate in a screw machine. In the screw machine of the present invention, the interface surface area between the rotor end faces and the end casing is reduced by reason of a reduction in the surface area of at least either the rotor end faces or the facing surface of the outlet casing. In one embodiment of the present invention, discrete, non-interconnected, relatively large depressions are formed in the rotor end faces. In another embodiment, the rotor end faces may have a textured surface providing a multiplicity of interconnected, relatively small depressions. In another embodiment of the present invention, the surface of the outlet casing facing the rotor end faces is textured or otherwise provided with depressions.
- For a fuller understanding of the present invention, reference should now be made to the following detailed description of various embodiments thereof and to the accompanying drawings wherein:
- FIG. 1 is a transverse section through a screw machine;
- FIG. 2 is a partially sectioned view of the screw machine of FIG. 1;
- FIG. 3 is an enlarged view of a portion of the discharge end of the screw machine of FIG. 1;
- FIG. 4 is an end view of the rotors taken along line4-4 of FIG. 3 showing one embodiment of the end faces of the rotors;
- FIG. 5 is an end view of the rotors showing an alternate embodiment of the end faces of the rotors: and
- FIG. 6 is an end view of the rotors showing a further alternate embodiment of the end faces of the rotors.
- Referring now to FIG. 1, there is depicted a
screw machine 10, such as a screw compressor, having a rotor housing orcasing 12 with a pair of overlappingbores Female rotor 14 is located inbore 13 andmale rotor 16 is located inbore 15. Thebores female rotor 14 has sixlobes 14A separated by six flutes, whilemale rotor 16 has five lobes separated by five flutes. Accordingly, the rotational speed ofrotor 16 will be 6/5 or 120% of that ofrotor 14. Either thefemale rotor 14 or themale rotor 16 may be connected to a prime mover (not illustrated) and serve as the driving rotor. Other combinations of the number of female and male lands and grooves may also be used. - Referring now to FIGS. 2 and 3,
rotor 14 has ashaft portion 23 with anend face 24 formed on the end of therotor 14 radially outward of theshaft portion 23.Shaft portion 23 ofrotor 14 is supported in outlet ordischarge casing 53 by one, or more, bearing(s) 30. Similarly,rotor 16 has ashaft portion 25 with anend face 26 formed on the end of therotor 16 radially outward of theshaft portion 26.Shaft portion 25 ofrotor 16 is supported inoutlet casing 53 by one, or more bearing(s) 31. Suctionside shaft portions rotors rotor housing 12 byroller bearings - In operation, for example as a refrigerant compressor, assuming
male rotor 16 to be the driving rotor,rotor 16 rotates engagingrotor 14 and causing its rotation. The coaction of rotatingrotors respective bores suction inlet 18 into the grooves ofrotors discharge port 19. For the reasons discussed hereinbefore, it is necessary to maintain an end-runningclearance 60 between the end faces 24 and 26 at the discharge ends of therotors surface 51 of theend plate 55 ofoutlet casing 53. Thisend running clearance 60 is defined as the region between the closest interface surfaces of therotor end faces surface 51 of theend plate 55. Thisend running clearance 60 establishes a potential gas leakage path, both circumferential and radial, betweenrotor end faces end plate 55 of theoutlet casing 53. As in conventional oil-flooded compressors, lubrication oil that naturally flows into the end-runningclearance 60 serves as a seal to reduce gas leakage through the end-running clearance. - In accordance with the present invention, the interface surface area defining the
end running clearance 60 between the rotor end faces 24 and 26 and the facingsurface 51 of theend plate 55 of theoutlet casing 53 is reduced by removing material from therotor end faces surface 51 of theend plate 55. As the interface area for a given end running clearance is reduced, the friction losses caused by viscous forces due to the oil in the region between therotor end faces surface 51 of theend plate 51 of theoutlet casing 53 is reduced. - In the embodiment of the present invention illustrated in FIG. 4, discrete,
depressions rotor end faces Depression 44 is provided in the central region of theend face 24 of thefemale rotor 14 to extend about theshaft 23 anddepressions 44A are formed in thelobes 14A. Similarly,depression 46 is provided in the central region of theend face 26 of themale rotor 16 to extend about theshaft 25 anddepressions 46A are formed in thelobes 16A. Theshoulders 45 separate therespective depressions rotor end face 24 and theshoulders 47 separate therespective depressions rotor end face 26. Thus, thedepressions shoulders depressions - In another embodiment of the present invention illustrated in FIG. 5,
discrete depressions depressions shoulder portions 55 and 57, respectively, and the interface surface area is reduced to the surface area of the shoulder portions. The depth of thedepressions - In a further embodiment of the present invention as illustrated in FIG. 6, the surface of each of the rotor end faces24 and 26 comprises a textured surface having a plurality of
small depressions 64 formed betweenrises 66 and dispersed extensively across substantially the entire surface of the rotor end faces. The interface surface area is reduced to the surface area of the rises rather than the surface area of the overall rotor end face. Again, the depth of thedepressions 64, are not critical to the invention, but advantageously have a depth in the range from about 0.001 inch to about 0.20 inch. - After studying the embodiments described hereinbefore and illustrated in the drawings, one skilled in the art will recognize modifications in the described embodiments. For example, the interface area between the rotor end faces24 and 26 and the facing
surface 51 of theoutlet casing 53 may be reduced in accordance with the present invention by providing depressions in or a textured surface on the facingsurface 51. - Although the present invention has been specifically illustrated and described in terms of a twin rotor screw machine, it is applicable to screw machines employing three, or more rotors. Therefore, the present invention is intended to be limited only by the scope of the appended claims.
Claims (4)
1. A screw machine comprising a housing defining at least one pair of parallel, overlapping bores, an outlet casing having a facing surface, and a conjugate pair of intermeshing rotors located in said at least one pair of bores, each of said rotors having an end face, said end faces of said rotors being spaced from said facing surface of the outlet casing and defining therewith an interface area; characterized by the interface area being reduced by reason of a reduction in the surface area of at least either said rotor end faces or said facing surface of the outlet casing.
2. The screw machine of wherein at least one depression is formed in said rotor end faces.
claim 1
3. The screw machine of wherein a plurality of discrete, unconnected depressions are formed in each of said rotor end faces.
claim 1
4. The screw machine of wherein said rotor end faces comprise textured surfaces.
claim 1
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/742,978 US20010031213A1 (en) | 1999-12-20 | 2000-12-20 | Screw machine |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US17276799P | 1999-12-20 | 1999-12-20 | |
US09/742,978 US20010031213A1 (en) | 1999-12-20 | 2000-12-20 | Screw machine |
Publications (1)
Publication Number | Publication Date |
---|---|
US20010031213A1 true US20010031213A1 (en) | 2001-10-18 |
Family
ID=22629148
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/742,978 Abandoned US20010031213A1 (en) | 1999-12-20 | 2000-12-20 | Screw machine |
Country Status (3)
Country | Link |
---|---|
US (1) | US20010031213A1 (en) |
AU (1) | AU2581301A (en) |
WO (1) | WO2001046562A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
TWI705185B (en) * | 2018-08-29 | 2020-09-21 | 日商日立產機系統股份有限公司 | Screw rotor and screw fluid machine body |
CN111727323A (en) * | 2018-03-30 | 2020-09-29 | 株式会社日立产机*** | Screw rotor and fluid machine body |
CN111836964A (en) * | 2018-03-30 | 2020-10-27 | 株式会社日立产机*** | Screw rotor, fluid machine body, and fluid machine |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6290480B1 (en) * | 1999-12-20 | 2001-09-18 | Carrier Corporation | Screw machine |
BE1017582A3 (en) * | 2007-03-05 | 2009-01-13 | Atlas Copco Airpower Nv | Fluid injected screw compressor, has relief pattern on casing or rotor outlet end face for creating film seal |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2232592C3 (en) * | 1972-07-03 | 1978-09-14 | Wankel Gmbh, 1000 Berlin | Loading and exhaust rotary piston machine |
US4417859A (en) * | 1979-10-04 | 1983-11-29 | Praner Frank Casimir | Rotary displacement turbine engine with vacuum relief valve means |
FR2508113A1 (en) * | 1981-06-17 | 1982-12-24 | Zimmern Bernard | VOLUMETRIC MACHINE WITH SCREW AND SPROCKETS |
JPS59176487A (en) * | 1983-03-25 | 1984-10-05 | Hitachi Ltd | Rotor of screw compressor |
DE3609996C2 (en) * | 1986-03-25 | 1994-10-20 | Mahle Gmbh | Screw compressor |
WO1992009807A1 (en) * | 1990-11-30 | 1992-06-11 | Kabushiki Kaisha Maekawa Seisakusho | Fluid jetting type screw compressor |
-
2000
- 2000-12-15 WO PCT/US2000/034198 patent/WO2001046562A1/en active Application Filing
- 2000-12-15 AU AU25813/01A patent/AU2581301A/en not_active Abandoned
- 2000-12-20 US US09/742,978 patent/US20010031213A1/en not_active Abandoned
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN111727323A (en) * | 2018-03-30 | 2020-09-29 | 株式会社日立产机*** | Screw rotor and fluid machine body |
CN111836964A (en) * | 2018-03-30 | 2020-10-27 | 株式会社日立产机*** | Screw rotor, fluid machine body, and fluid machine |
US11225965B2 (en) * | 2018-03-30 | 2022-01-18 | Hitachi Industrial Equipment Systems Co., Ltd. | Screw rotor and fluid machine body |
US11415134B2 (en) * | 2018-03-30 | 2022-08-16 | Hitachi Industrial Equipment Systems Co., Ltd. | Screw rotor, fluid machine main body, and fluid machine |
TWI705185B (en) * | 2018-08-29 | 2020-09-21 | 日商日立產機系統股份有限公司 | Screw rotor and screw fluid machine body |
CN112513465A (en) * | 2018-08-29 | 2021-03-16 | 株式会社日立产机*** | Screw rotor and screw fluid machine body |
JPWO2020044715A1 (en) * | 2018-08-29 | 2021-08-10 | 株式会社日立産機システム | Screw rotor and screw fluid machine body |
JP7141459B2 (en) | 2018-08-29 | 2022-09-22 | 株式会社日立産機システム | Screw rotor and screw fluid machine body |
US11536270B2 (en) | 2018-08-29 | 2022-12-27 | Hitachi Industrial Equipment Systems Co., Ltd. | Screw rotor and screw-type fluid machine main body |
Also Published As
Publication number | Publication date |
---|---|
AU2581301A (en) | 2001-07-03 |
WO2001046562A1 (en) | 2001-06-28 |
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Legal Events
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AS | Assignment |
Owner name: CARRIER CORPORATION, CONNECTICUT Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LIU, XIN;SHOULDERS, STEPHEN;STUDNIARZ, DEADRA;REEL/FRAME:011769/0734;SIGNING DATES FROM 20010420 TO 20010424 |
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |