EP0194957A2 - Compressor blade tip seal - Google Patents
Compressor blade tip seal Download PDFInfo
- Publication number
- EP0194957A2 EP0194957A2 EP86630032A EP86630032A EP0194957A2 EP 0194957 A2 EP0194957 A2 EP 0194957A2 EP 86630032 A EP86630032 A EP 86630032A EP 86630032 A EP86630032 A EP 86630032A EP 0194957 A2 EP0194957 A2 EP 0194957A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- engine
- trench
- blades
- tips
- wall
- 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.)
- Granted
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
- F01D5/12—Blades
- F01D5/14—Form or construction
- F01D5/20—Specially-shaped blade tips to seal space between tips and stator
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
- F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/08—Sealings
- F04D29/16—Sealings between pressure and suction sides
- F04D29/161—Sealings between pressure and suction sides especially adapted for elastic fluid pumps
- F04D29/164—Sealings between pressure and suction sides especially adapted for elastic fluid pumps of an axial flow wheel
Definitions
- This invention relates to axial flow fans/compressors of gas turbine engines and particularly to the relationship of the tips of the blades to the adjacent shroud or rub strip.
- the tips of the compressor blades extend adjacent the surrounding shroud or rub strip that is trenched or recessed to the dimension complimentary to the outer station and tip of the blade.
- the blades which move radially outward during engine acceleration, machine the groove. Obviously, this technique assures a close fit of the mating parts and helps in avoiding leakage around the tips of the blade.
- a feature of the invention is to provide a slanted trench in the rub strip, shroud, or the engine case of a gas turbine engine adjacent the tips of the blades of the fan and/or compressor.
- the contour of the blade and the inner wall as seen by the cross section of the trench is angularly disposed relative to the flow path wall.
- This invention contemplates that the angular contour is designed to effectuate a closure in the gap between the inner wall of the trench and the tip of the blade upon displacement of the compressor and/or fan blade arising out of the growth of the materials resulting from stable speed and temperature operating conditions.
- the invention in its preferred embodiment is illustrated for use in the lower temperature stations of a gas turbine engine and particularly in the compressor section where a soft material circumscribes the engine's inner diameter of the engine case and is abradable so as to be susceptible of being machined by the operation of the rotating blades.
- a soft material circumscribes the engine's inner diameter of the engine case and is abradable so as to be susceptible of being machined by the operation of the rotating blades.
- the blades at zero rotational speeds are spaced from the inner diameter of the rub strip and when accelerated to its highest operating speed, cut into the rub strip to define the trench.
- the trench shape can be machined out prior to engine operation. What is considered the improvement by the teachings of this invention is the particular contour of the tips of the blades and its cooperating trench.
- FIG. 1 A portion of a compression section 10 of an axial flow compressor of a gas turbine engine is illustrated in Fig. 1.
- a flow path 16 for working medium gases extends axially through the compression section.
- An outer wall 18 having an inwardly facing surface 20 and an inner wall 22 having an outwardly facing surface 24 form the flow path.
- a plurality of axially spaced rows of rotor blades as represented by the single blades 26 extend outwardly from the rotor across the flow path into proximity with the outer wall.
- Each blade has an unshrouded tip 28 and is contoured to an airfoil cross section. Accordingly, each blade has a pressure side and a suction side and, as illustrated, has an upstream end 30 and a downstream end 32.
- Extending over the tips of each row of rotor blades is a stator seal land 34.
- Each land has a circumferentially extending groove 36 formed therein to a depth D at an inwardly facing surface 37 thereof.
- a plurality of rows of stator vanes represented by the single vanes 38 are cantilevered inwardly from the stator across the flow path into proximity with the inner wall.
- Each vane which in this illustration has an unshrouded tip 40, is contoured to an airfoil section. Accordingly, each vane has a pressure side and a suction side and, as illustrated, has an upstream end 42 and a downstream end 44.
- Extending over the tips of each row of stator vanes is a rotor seal land 46.
- Each land has a circumferentially extending groove 48 formed therein.
- the blade tips 26 are spaced from the inwardly facing surface 20.
- the gap between tips and surface enables assembly of the components.
- the rotor tips grow radially outward machining the groove 36 in the stator seal land 34.
- the point of closest proximity of the blades to the bottom of the groove is referred to as the "pinch point * and normally occurs during a transient engine operating to a maximum speed or power condition.
- the outer wall including the land moves both axially and radially relative to the blade tips to a position at which the blade tips and inner surface 37 define a gap.
- Fig. 2 which is a prior art design is that the blade 50 penetration into the trench increases with operating speed and causes pumping of air against the trench vertical wall 53 which creates turbulence.
- the turbulence as shown by arrow A essentially becomes a blockage in the flow path of the gas engine's working medium and adversely affects performance.
- the maximum depth of blade tip penetration must be controlled to avoid unreasonable turbulence losses at the maximum operating speed. At low speed operating the blade will not penetrate into the trench and leakage can readily occur between the flow path outer wall and the blade tip.
- the full width of the blade works on the air and has the tendency of over pressurizing this air and hence, creates the undesirable turbulence.
- the tip of the blade is contoured to be angularly disposed relative to the gas path wall. This is best seen in Fig. 3.
- the trench is formed to define the contour of the inner surface 37. Looking at the cross section of the trench it is apparent that the axial extension of surface 37 relative to the flow path defined by wall 20 forms angle alpha a. By virtue of this contour, two important features are realized:
- Fig. 4 exemplifies another configuration on how the tip can be contoured to combat the leakage problem alluded to in the above.
- the tip of blade 70 is contoured in a sawtooth fashion providing a plurality of parallel channels 72.
- the inner surface 74 is angularly disposed to the gas path wall providing similar benefits as was described above.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
Abstract
Description
- This invention relates to axial flow fans/compressors of gas turbine engines and particularly to the relationship of the tips of the blades to the adjacent shroud or rub strip.
- U.S. Patent No. 4,239,452 granted to Frank Roberts, Jr. on December 16, 1980 entitled Blade Tip Shroud for a Compressor Stage of a Gas Turbine Engine and U.S. Patent No. 4,238,170 granted to Brian A. Robideau and Juri Niiler on December 9, 1980 entitled Blade Tip Seal for an Axial Flow Rotary, both of which were assigned to United Technologies Corporation, the assignee common to the present patent application disclose shrouds that include trenches adjacent the tips of the blades.
- As desclosed in U.S. Patent No. 4,238,170 supra, for example, the tips of the compressor blades extend adjacent the surrounding shroud or rub strip that is trenched or recessed to the dimension complimentary to the outer station and tip of the blade. In some instances, say at the low pressure stages where soft abradable materials such as a synthetic rubber can be utilized, the blades which move radially outward during engine acceleration, machine the groove. Obviously, this technique assures a close fit of the mating parts and helps in avoiding leakage around the tips of the blade.
- The problem constantly plaguing the engine technical people is how to maintain this leakage to a minimum, if not prevent it. While the designs disclosed in the above mentioned-patents help toward this end, leakage is still prevalent.
- Other techniques for minimizing tip leakage is discussed in the above-mentioned patents. Suffice it to say that the present invention is an improvement over the techniques taught in these patents, supra, and serve to improve engine operating efficiencies over and above that attainable by the heretofore known designs.
- A feature of the invention is to provide a slanted trench in the rub strip, shroud, or the engine case of a gas turbine engine adjacent the tips of the blades of the fan and/or compressor. The contour of the blade and the inner wall as seen by the cross section of the trench is angularly disposed relative to the flow path wall.
- This invention contemplates that the angular contour is designed to effectuate a closure in the gap between the inner wall of the trench and the tip of the blade upon displacement of the compressor and/or fan blade arising out of the growth of the materials resulting from stable speed and temperature operating conditions. Other features and advantages will be apparent from the specification and claims and from the accompanying drawings which illustrate an embodiment of the invention.
-
- Fig. 1 is a partial view in section of a compressor section of a gas turbine engine schematically showing the slanted trench of the casing wall or rub strip of this invention.
- Fig. 2 is an enlarged view of a nonslanted trench adjacent the tip station of a compressor blade of the prior art design.
- Fig. 3 is an enlarged view of one of the blades and the attendant slanted trench in the engine casing, and
- Fig. 4 is a partial view of the tip stations and trench illustrating another embodiment of this invention.
- The invention in its preferred embodiment is illustrated for use in the lower temperature stations of a gas turbine engine and particularly in the compressor section where a soft material circumscribes the engine's inner diameter of the engine case and is abradable so as to be susceptible of being machined by the operation of the rotating blades. Thus, as disclosed in the U.S. Patent No. 4,238,170, supra, the blades at zero rotational speeds are spaced from the inner diameter of the rub strip and when accelerated to its highest operating speed, cut into the rub strip to define the trench. It is, however, to be understood and as will be obvious to one skilled in this art, the trench shape can be machined out prior to engine operation. What is considered the improvement by the teachings of this invention is the particular contour of the tips of the blades and its cooperating trench.
- A portion of a
compression section 10 of an axial flow compressor of a gas turbine engine is illustrated in Fig. 1. A flow path 16 for working medium gases extends axially through the compression section. Anouter wall 18 having an inwardly facing surface 20 and aninner wall 22 having an outwardly facing surface 24 form the flow path. A plurality of axially spaced rows of rotor blades as represented by thesingle blades 26 extend outwardly from the rotor across the flow path into proximity with the outer wall. Each blade has anunshrouded tip 28 and is contoured to an airfoil cross section. Accordingly, each blade has a pressure side and a suction side and, as illustrated, has an upstream end 30 and a downstream end 32. Extending over the tips of each row of rotor blades is astator seal land 34. Each land has a circumferentially extending groove 36 formed therein to a depth D at an inwardly facingsurface 37 thereof. - A plurality of rows of stator vanes represented by the
single vanes 38 are cantilevered inwardly from the stator across the flow path into proximity with the inner wall. Each vane, which in this illustration has an unshrouded tip 40, is contoured to an airfoil section. Accordingly, each vane has a pressure side and a suction side and, as illustrated, has anupstream end 42 and adownstream end 44. Extending over the tips of each row of stator vanes is arotor seal land 46. Each land has a circumferentially extending groove 48 formed therein. - In the nonoperating condition the
blade tips 26 are spaced from the inwardly facing surface 20. The gap between tips and surface enables assembly of the components. In response to centrifugally and thermally generated forces as the machine is accelerated , to high operating speeds the rotor tips grow radially outward machining the groove 36 in thestator seal land 34. The point of closest proximity of the blades to the bottom of the groove is referred to as the "pinch point* and normally occurs during a transient engine operating to a maximum speed or power condition. As the engine reaches thermal stability at a given operating speed the outer wall including the land, moves both axially and radially relative to the blade tips to a position at which the blade tips andinner surface 37 define a gap. - A problem with the heretofore design as illustrated in Fig. 2 which is a prior art design is that the
blade 50 penetration into the trench increases with operating speed and causes pumping of air against the trench vertical wall 53 which creates turbulence. The turbulence as shown by arrow A, essentially becomes a blockage in the flow path of the gas engine's working medium and adversely affects performance. The maximum depth of blade tip penetration must be controlled to avoid unreasonable turbulence losses at the maximum operating speed. At low speed operating the blade will not penetrate into the trench and leakage can readily occur between the flow path outer wall and the blade tip. - Ideally, it is desirable to match the pressure gradient across the tip which tends to leak air from the high pressure side to the low pressure side by the pressure created by the tip pumping action. In the heretofore shown embodiment the full width of the blade works on the air and has the tendency of over pressurizing this air and hence, creates the undesirable turbulence.
- According to this invention the tip of the blade is contoured to be angularly disposed relative to the gas path wall. This is best seen in Fig. 3. As the trench is machined as described above, the trench is formed to define the contour of the
inner surface 37. Looking at the cross section of the trench it is apparent that the axial extension ofsurface 37 relative to the flow path defined by wall 20 forms angle alpha a. By virtue of this contour, two important features are realized: - (1) The full width of the blade pumped against the vertical trench wall in the situation of the heretofore design as soon as any portion of the blade tip penetrated into the trench. Thus the blade penetration is minimal prior to creating undesirable turbulence. Only the aft portion of the blade tip pumps against the trench vertical wall in Figure 2 when the speed is attained to cause the blade tip to penetrate into the trench. Thus the blade tip can penetrate deeper into the trench prior to creating the limiting condition of turbulence. At lower operating speed conditions the revised tip design will permit penetration whereas the heretofore design did not permit penetration. (2) By slanting the trench in the proper direction, the gap will be reduced by the relative axial motion between the blade tip and trench outer wall as these engine parts achieve thermal stability at any given engine speed condition. Thus knowing the axial growth direction of the case, say in the direction of the arrow B relative to the blade's axial motion, it is apparent that gap D tends to become smaller.
- Fig. 4 exemplifies another configuration on how the tip can be contoured to combat the leakage problem alluded to in the above. As noted the tip of blade 70 is contoured in a sawtooth fashion providing a plurality of
parallel channels 72. In each channel theinner surface 74 is angularly disposed to the gas path wall providing similar benefits as was described above. - The preferred embodiment described in connection with Fig. 3 has proven to be particularly efficacious resulting in perhaps a 0.1 or 0.2% improvement in specific fuel consumption as evidenced on the PW2037 engine manufactured by Pratt & Whitney Aircraft of United Technologies Corporation, the assignee of this patent application.
- It should be understood that the invention is not limited to the particular embodiments shown and described herein, but that various changes and modifications may be made without departing from the spirit and scope of this novel concept as defined by the following claims.
Claims (5)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US71027085A | 1985-03-11 | 1985-03-11 | |
US710270 | 1985-03-11 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0194957A2 true EP0194957A2 (en) | 1986-09-17 |
EP0194957A3 EP0194957A3 (en) | 1987-06-03 |
EP0194957B1 EP0194957B1 (en) | 1990-01-31 |
Family
ID=24853314
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86630032A Expired - Lifetime EP0194957B1 (en) | 1985-03-11 | 1986-03-06 | Compressor blade tip seal |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0194957B1 (en) |
JP (1) | JPS61207802A (en) |
DE (2) | DE3668661D1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0528138A1 (en) * | 1991-08-08 | 1993-02-24 | Asea Brown Boveri Ag | Blade shroud for axial turbine |
EP0536575A1 (en) * | 1991-10-08 | 1993-04-14 | Asea Brown Boveri Ag | Shroud band for axial flow turbine |
DE19738671A1 (en) * | 1997-09-04 | 1999-03-11 | Abb Research Ltd | Seal between rotary and stationary components e.g. in axial flow steam turbines |
EP1840332A1 (en) * | 2006-03-27 | 2007-10-03 | Siemens Aktiengesellschaft | Blade of a turbomachine and turbomachine |
WO2014189564A3 (en) * | 2013-03-06 | 2015-02-19 | United Technologies Corporation | Pretrenched rotor for gas turbine engine |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6363726A (en) * | 1986-09-05 | 1988-03-22 | Nippon Shokubai Kagaku Kogyo Co Ltd | Composition for surface treatment |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CH221391A (en) * | 1939-04-06 | 1942-05-31 | Maschf Augsburg Nuernberg Ag | Gap sealing device on the heads of the blading of turbomachines, especially steam turbines. |
DE1057137B (en) * | 1958-03-07 | 1959-05-14 | Maschf Augsburg Nuernberg Ag | Blade gap seal on centrifugal machines with impellers without a cover band or cover disk |
GB882015A (en) * | 1957-04-18 | 1961-11-08 | English Electric Co Ltd | Improvements in and relating to high speed axial flow compressors |
FR1348186A (en) * | 1963-02-19 | 1964-01-04 | Faired propeller | |
CH414681A (en) * | 1964-11-24 | 1966-06-15 | Bbc Brown Boveri & Cie | Turbo machine |
US3575523A (en) * | 1968-12-05 | 1971-04-20 | Us Navy | Labyrinth seal for axial flow fluid machines |
GB2034435A (en) * | 1978-10-24 | 1980-06-04 | Gerry U | Fluid rotary power conversion means |
GB2153918A (en) * | 1984-02-06 | 1985-08-29 | Gen Electric | Compressor casing recess |
-
1986
- 1986-03-04 JP JP61047177A patent/JPS61207802A/en active Pending
- 1986-03-06 DE DE8686630032T patent/DE3668661D1/en not_active Expired - Fee Related
- 1986-03-06 EP EP86630032A patent/EP0194957B1/en not_active Expired - Lifetime
- 1986-03-06 DE DE198686630032T patent/DE194957T1/en active Pending
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CH221391A (en) * | 1939-04-06 | 1942-05-31 | Maschf Augsburg Nuernberg Ag | Gap sealing device on the heads of the blading of turbomachines, especially steam turbines. |
GB882015A (en) * | 1957-04-18 | 1961-11-08 | English Electric Co Ltd | Improvements in and relating to high speed axial flow compressors |
DE1057137B (en) * | 1958-03-07 | 1959-05-14 | Maschf Augsburg Nuernberg Ag | Blade gap seal on centrifugal machines with impellers without a cover band or cover disk |
FR1348186A (en) * | 1963-02-19 | 1964-01-04 | Faired propeller | |
CH414681A (en) * | 1964-11-24 | 1966-06-15 | Bbc Brown Boveri & Cie | Turbo machine |
US3575523A (en) * | 1968-12-05 | 1971-04-20 | Us Navy | Labyrinth seal for axial flow fluid machines |
GB2034435A (en) * | 1978-10-24 | 1980-06-04 | Gerry U | Fluid rotary power conversion means |
GB2153918A (en) * | 1984-02-06 | 1985-08-29 | Gen Electric | Compressor casing recess |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0528138A1 (en) * | 1991-08-08 | 1993-02-24 | Asea Brown Boveri Ag | Blade shroud for axial turbine |
US5238364A (en) * | 1991-08-08 | 1993-08-24 | Asea Brown Boveri Ltd. | Shroud ring for an axial flow turbine |
EP0536575A1 (en) * | 1991-10-08 | 1993-04-14 | Asea Brown Boveri Ag | Shroud band for axial flow turbine |
DE19738671A1 (en) * | 1997-09-04 | 1999-03-11 | Abb Research Ltd | Seal between rotary and stationary components e.g. in axial flow steam turbines |
DE19738671B4 (en) * | 1997-09-04 | 2007-03-01 | Alstom | sealing arrangement |
EP1840332A1 (en) * | 2006-03-27 | 2007-10-03 | Siemens Aktiengesellschaft | Blade of a turbomachine and turbomachine |
WO2014189564A3 (en) * | 2013-03-06 | 2015-02-19 | United Technologies Corporation | Pretrenched rotor for gas turbine engine |
US10550699B2 (en) | 2013-03-06 | 2020-02-04 | United Technologies Corporation | Pretrenched rotor for gas turbine engine |
Also Published As
Publication number | Publication date |
---|---|
EP0194957B1 (en) | 1990-01-31 |
DE3668661D1 (en) | 1990-03-08 |
EP0194957A3 (en) | 1987-06-03 |
JPS61207802A (en) | 1986-09-16 |
DE194957T1 (en) | 1987-03-19 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4738586A (en) | Compressor blade tip seal | |
US4239452A (en) | Blade tip shroud for a compression stage of a gas turbine engine | |
EP0781371B1 (en) | Dynamic control of tip clearance | |
EP0792410B1 (en) | Rotor airfoils to control tip leakage flows | |
US5261789A (en) | Tip cooled blade | |
EP3361053B1 (en) | Grooved shroud casing treatment for high pressure compressor in a turbine engine | |
US4169692A (en) | Variable area turbine nozzle and means for sealing same | |
US4238170A (en) | Blade tip seal for an axial flow rotary machine | |
EP3183428B1 (en) | Compressor aerofoil | |
EP0774050B1 (en) | Interrupted circumferential groove stator structure | |
EP1895108A2 (en) | Angel wing abradable seal and sealing method | |
US4645417A (en) | Compressor casing recess | |
EP0801209A2 (en) | Tip sealing for turbine rotor blade | |
US4606699A (en) | Compressor casing recess | |
EP3064709B1 (en) | Turbine bucket platform for influencing hot gas incursion losses | |
EP3392459A1 (en) | Compressor blades | |
JPS60206903A (en) | Turbine power blade | |
EP0194957A2 (en) | Compressor blade tip seal | |
US6129513A (en) | Fluid seal | |
GB2034435A (en) | Fluid rotary power conversion means | |
EP3722555B1 (en) | Turbine section having non-axisymmetric endwall contouring with forward mid-passage peak | |
US4460309A (en) | Compression section for an axial flow rotary machine | |
US3580692A (en) | Seal construction | |
CN114251130B (en) | Robust rotor structure and power system for controlling blade tip leakage flow | |
GB2161220A (en) | Gas turbine stator vane assembly |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): DE FR GB SE |
|
EL | Fr: translation of claims filed | ||
DET | De: translation of patent claims | ||
PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
AK | Designated contracting states |
Kind code of ref document: A3 Designated state(s): DE FR GB SE |
|
17P | Request for examination filed |
Effective date: 19870625 |
|
17Q | First examination report despatched |
Effective date: 19880321 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): DE FR GB SE |
|
ET | Fr: translation filed | ||
REF | Corresponds to: |
Ref document number: 3668661 Country of ref document: DE Date of ref document: 19900308 |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 19910211 Year of fee payment: 6 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: SE Payment date: 19910218 Year of fee payment: 6 Ref country code: GB Payment date: 19910218 Year of fee payment: 6 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 19910228 Year of fee payment: 6 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Effective date: 19920306 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Effective date: 19920307 |
|
GBPC | Gb: european patent ceased through non-payment of renewal fee | ||
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Effective date: 19921130 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Effective date: 19921201 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |
|
EUG | Se: european patent has lapsed |
Ref document number: 86630032.0 Effective date: 19921005 |