CN109991482A - The simulation electrode device of cable insulation space charge detection - Google Patents
The simulation electrode device of cable insulation space charge detection Download PDFInfo
- Publication number
- CN109991482A CN109991482A CN201711467699.2A CN201711467699A CN109991482A CN 109991482 A CN109991482 A CN 109991482A CN 201711467699 A CN201711467699 A CN 201711467699A CN 109991482 A CN109991482 A CN 109991482A
- Authority
- CN
- China
- Prior art keywords
- sample
- cable
- electrode
- guide rod
- space charge
- 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.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/24—Arrangements for measuring quantities of charge
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Relating To Insulation (AREA)
Abstract
A kind of simulation electrode device of cable insulation space charge detection, it is characterized in that, it include: to test probe mechanism, the equivalent insulating layer sample of target cable of earthing mechanism and setting therebetween, in which: the two sides of the equivalent insulating layer sample of target cable are equipped with shielded layer;Testing probe mechanism includes: guide rod and the voltage equalizing ball and electrode for being set to its both ends, in which: the metal cavity of tetrafluoroethene column and internal filling epoxy resin is successively arranged outside guide rod.The present invention can be before target cable formally produces, according to the structure size of cable, insulating materials type selecting, distribution of space charge information of the simulated target cable under operating condition.
Description
Technical field
It is specifically a kind of to be suitable for coaxial configuration cable insulation the present invention relates to a kind of technology in power transmission material field
The simulation electrode device of sheaf space charge detection.
Background technique
To solve space charge accumulation of the flexible DC transmission cable insulation under operating condition, examined based on different charges
The space charge detection technique and device for surveying principle have obtained extensive development, wherein the application with electroacoustic pulse is the most universal.
The space charge detection of existing flexible DC transmission cable insulation mainly divides two major classes, and one kind is the exhausted of direct current cables insulating layer
Edge slice detection extracts the insulation slice of cable insulation different location, then with plate electrode knot by insulation slicer
Structure device carries out space charge detection, to obtain the distribution of space charge information in different insulative layer material;Another kind of is direct current
The direct detection of cable carries out space charge to cable insulation using coaxial configuration device and directly detects.Two class detection sides
In method, the second class is detected closest to actual cable structure, but for the design of direct current cables and exploitation, such detection is deposited
Limitation both ways: being to need factory rule of thumb to design in advance and produce target cable sample first, followed by electric
Layer is thicker due to cable insulation in the on-site test of cable space charge, to the more demanding of detection device and place.
Above-mentioned two big limitation causes the space charge testing cost expense to practical coaxial configuration cable larger, detection week
Phase is longer, can not formally produce the information in terms of preceding design and exploitation for target cable provides space charge in direct current cables.
Therefore it needs to improve existing detection technique, be supported to provide detection technique for the development of actual DC cable.
Summary of the invention
The present invention In view of the above shortcomings of the prior art, proposes a kind of simulation of cable insulation space charge detection
Electrode assembly, can be before target cable formally produces, according to the structure size of cable, insulating materials type selecting, simulated target electricity
Distribution of space charge information of the cable under operating condition.
The present invention is achieved by the following technical solutions:
The present invention includes: to test the equivalent insulating layer examination of probe mechanism, the target cable of earthing mechanism and setting therebetween
Sample, in which: the two sides of the equivalent insulating layer sample of target cable are equipped with shielded layer.
The test probe mechanism includes: guide rod and the voltage equalizing ball and electrode for being set to its both ends, in which: outside guide rod
Portion is successively arranged the metal cavity of tetrafluoroethene column and internal filling epoxy resin.
The electrode is adjustable high-voltage metal electrode, and main body is fan-shaped column structure, and main body upper end passes through spiral shell
Line structure is connect with guide rod, and central angle and the equivalent insulating layer sample central angle of target cable of fan-shaped surface are consistent, the electricity
Pole lower surface is contacted by internal shield tight and with sample inner surface, high pressure needed for applying to specimen surface.
Metal plate and tetrafluoroethene ring are respectively equipped at the top and bottom of the epoxy resin, the outside of epoxy resin is set
There is metal cavity.
The earthing mechanism includes: earth plate and is used to detect that the sound generated in cable insulation to be believed positioned at its bottom
Number piezoelectric transducer, by piezoelectric transducer by acoustical signal be converted to electric signal and export to signal acquisition control system carry out
Record and analysis processing, display space charge measurements.
The guide rod is equipped with the high-voltage capacitance for isolated DC voltage.
The present invention relates to the electroacoustic pulse detecting methods of above-mentioned apparatus, comprising the following steps:
Step 1, assembling test probe mechanism: tetrafluoroethene insulation sleeve column, ring type filling in metal cavity are set outside guide rod
The top and bottom for testing probe mechanism entirety are connected with metal top cover plate and insulation lower cover plate, by guide rod by oxygen resin respectively
There is the external thread structure Matching installation of internal thread structure and adjustable high-voltage metal electrode upper end protrusion in lower end and is embedded at lower cover
The middle part of plate forms the top electrode of Integral movable;
Step 2, it prepares the equivalent insulation sample of target cable and is placed under adjustable high-voltage metal electrode, in metal electrode following table
Face is arranged shielded layer and wraps up, and is placed on earth plate after sample lower surface and shielded layer are fitted closely;
Step 3, the metal screw of even numbers quantity is passed through to the metal cover board two sides vertical core being placed on test probe mechanism and is led to
Cross the fixed test probe mechanism of nut and earth plate;The distance between upper and lower electrode is adjusted by nut, to adapt to different rule
The equivalent insulation sample of the target cable of lattice;
Step 4, DC high voltage is introduced into high-pressure metal electrode by conducting rod, then by piezoelectric transducer reception space
The acoustical signal of charge, and electric signal, output to signal acquisition control system are converted by acoustical signal.
Technical effect
In existing space charge distribution measurement techniques, most widely used is flat sheet insulation sample, full-scale coaxial knot
The space charge measurement of structure cable insulation, these two types of measurement methods all have certain limitation: flat sheet insulation sample
Measurement result can not be truly reflected the actual conditions of coaxial configuration cable;The measurement of full-scale coaxial configuration cable is accurate
Degree is higher, but sample preparation is not easy, expensive.
Compared with prior art, present invention employs curved surface electrode, equivalent samples carries out instead of coaxial configuration target cable
Space charge measurement in insulating layer, it is known that the actual parameter of target cable can prepare the equivalent sample of cable insulation, choosing
The adjustable metal electrode for selecting appropriate size, is mounted on test probe mechanism, carries out the measurement of space charge.
The preparation cost that the present invention solves coaxial configuration target cable is high, verifying detects, and difficult, lead time length etc. is many
Problem, and using the improved simulation electrode constructional device of the present invention, in measurement process can guarantee that equivalent sample is vertical
The operating condition in heart district domain is consistent with target cable insulating layer truth, greatly improves testing efficiency, have measurement it is accurate, can
The advantages that high by property.
Detailed description of the invention
Fig. 1 is invention overall structure diagram;
Fig. 2 is the schematic perspective view of adjustable metal electrode;
Fig. 3 is equivalent sample of the invention and the field distribution comparison diagram really to insulate;
In figure: 1 presses metal ball, 2 guide rods, 3 metal plates, 4 tetrafluoroethene columns, 5 metal cavities, 6 epoxy resin, 7 tetrafluoros
Ethylene ring, 8 adjustable high-voltage metal electrodes, 9 internal shields, the equivalent insulating layer sample of 10 target cables, 11 external shielding layers, 12 connect
Floor, 13 piezoelectric transducers, 14 metal cover boards, 15 nuts, 16 metal screws, 17 pulse conducting rods, 18 pulse insulating sleeves, 19
High-voltage capacitance.
Specific embodiment
As shown in Figure 1, in the present embodiment, the test probe mechanism include: press metal ball 1, guide rod 2, metal plate 3,
Tetrafluoroethene column 4, metal cavity 5, epoxy resin 6, tetrafluoroethene ring 7, adjustable high-voltage metal electrode 8, in which: guide rod 2
Metal ball 1, end connected adjustable high-pressure metal electrode 8, and housing tetrafluoroethene insulation sleeve column 4 are pressed in head end connection;Gold
Belong to and fill epoxy resin 6 in cavity 5, there is external thread structure in 8 upper end of adjustable high-voltage metal electrode, passes through spiral shell with 2 end of guide rod
Line matching is connected, and is surrounded and be fixed in metal cavity 5 by tetrafluoroethene ring 7, and last metal plate 3 binds, and is formed whole removable
Dynamic high-field electrode system.
As shown in Fig. 2, the adjustable high-voltage metal electrode 8, main body is fan-shaped column structure, and main body upper end is logical
It crosses helicitic texture to connect with guide rod, covering of the fan central angle is consistent with the equivalent insulating layer sample central angle of target cable, the electricity
Pole lower surface is contacted by internal shield tight, and with sample inner surface.
The equivalent insulating layer sample 10 of the target cable is obtained by two parallel partial cylinder shape die castings,
Inside and outside diameter is consistent with target cable insulating layer;The value of central angle needs to solve by emulation, in guaranteeing that sample is vertical
Heart district domain field distribution is identical as the true field distribution of target cable, and the optional range of central angle is 0-180 degree.
The external shielding layer 11 is thin semiconducting material, and inside is fitted closely with sample outer surface, the corresponding center of circle
Angle is less than high-pressure metal electrode and corresponds to central angle, determines that the optional range of central angle is 0-180 degree by emulation.
The metal cover board 14, two sides have a vertical core, are placed on metal plate 3, press metal ball from center
It passes through.The metal screw 16 of even numbers quantity passes through metal cover board two sides vertical core, is screwed with the fixed test probe mechanism of nut 15 and connects
Floor.The distance between upper and lower electrode is adjusted by nut, to adapt to the electrode and sample of different size.
The pressure metal ball 1 is the metal copper ball of polishing.
The material of the guide rod 2 is iron.
The metal plate 3, metal cavity 5, high-pressure metal electrode 8, earth plate 12 material be aluminium.
The guide rod 2 cooperates with metal ball 1,8 helicitic texture of high-pressure metal electrode is pressed.
The adjustable high-voltage metal electrode 8, internal shield 9, the equivalent insulating layer sample 10 of target cable, external shielding layer
11,12 coaxial placement of earth plate.
The earth plate 12 is connected with piezoelectric transducer 13, and size is not less than external shielding layer.
The pulse conducting rod 17, for introducing the high-voltage pulse to the high-pressure metal electrode.
The pulse insulating sleeve 18, ring set is on the outside of pulse conducting rod.
The high-voltage capacitance 19, for the DC voltage to be isolated and by the high-voltage pulse.
It is alternatively possible to instill silicone oil between high-pressure metal electrode and equivalent sample, to eliminate the air gap of contact surface, mention
The reliability of high measuring accuracy and test result.
A kind of simulation electrode device suitable for the detection of coaxial configuration cable insulation space charge of the present invention,
When for space charge measurement, required high direct voltage accesses guide rod by pressure metal ball, and high voltage pulse passes through pulse conduction
Bar accesses guide rod, and the adjustable metal electrode being connected with guide rod can apply high direct voltage and high voltage pulse to sample.
In the present embodiment, the inside radius of target cable insulating layer tests the adjustable high-voltage of probe mechanism with a thickness of 15mm
Metal electrode, covering of the fan radius take 15mm, and central angle takes 160 degree.
In the present embodiment, the inside radius of target cable insulating layer is with a thickness of 15mm, outer radius 32mm;Equivalent sample and mesh
The internal-and external diameter of mark cable insulation is consistent, and inside radius takes 15mm, and outer radius takes 32mm, and central angle takes 160 degree, with high pressure gold
Belong to the covering of the fan central angle of electrode, convenient for the installation of high-pressure metal electrode.
In the present embodiment, the inside radius of inner shield semi-conductive layer takes 14mm, and outer radius takes 15mm, and central angle takes 160 degree, can
Lower end surface by wrapping up high-pressure metal electrode, so that high-pressure metal electrode and equivalent sample inside diameter surface well contact;External shield
The inside radius of semi-conductive layer takes 32mm, and outer radius takes 33mm, and central angle takes 120 degree.
Based on the above parameter, by the simulation result for comparing following experiments, it was demonstrated that the reliability of apparatus of the present invention: (1) right
The insulating layer electric field of coaxial configuration target cable is emulated;(2) identical extra electric field condition is kept, is hung down to equivalent sample
Straight central area electric field is emulated.The result of emulation experiment is as shown in Fig. 2, solid line expression is that coaxial configuration cable to be measured is exhausted
In edge layer vertical center area, the relative electric field strength size of different radial positions, what dotted line indicated is the vertical of equivalent sample
In central area, the relative electric field strength size of different radial positions.
It can be seen that from the curve tendency in Electric Field Simulation figure in the vertical of coaxial configuration cable insulation and equivalent sample
In central area, radial position is remoter with high-pressure metal electrode distance, and relative electric field strength is smaller, this shows: using the present invention
Simulation electrode device carry out space charge measurement, under the conditions of capable of guaranteeing identical extra electric field, equivalent sample with it is to be measured coaxial
Structural cable insulating layer possesses almost the same field distribution, and experimental result has reliability, accuracy.
The present invention innovatively uses the equivalent sample of target cable insulating layer, adjustable high-voltage metal electrode structure, can
Before target cable formally produces, according to the structure size of cable, insulating materials type selecting, the equivalent examination of cable insulation is made
Sample, the sample preparation that can solve full-scale cable in the prior art are not easy problem, can really reflect coaxial configuration cable
Distribution of space charge information under insulating layer operating condition.Apparatus of the present invention have convenient to carry out, high reliablity, measurement accurate
Advantage has broad application prospects.
Above-mentioned specific implementation can by those skilled in the art under the premise of without departing substantially from the principle of the invention and objective with difference
Mode carry out local directed complete set to it, protection scope of the present invention is subject to claims and not by above-mentioned specific implementation institute
Limit, each implementation within its scope is by the constraint of the present invention.
Claims (6)
1. a kind of simulation electrode device of cable insulation space charge detection characterized by comprising test probe mechanism,
The equivalent insulating layer sample of target cable of earthing mechanism and setting therebetween, in which: the equivalent insulating layer sample of target cable
Two sides are equipped with shielded layer;
The test probe mechanism includes: guide rod and the voltage equalizing ball and electrode for being set to its both ends, in which: outside guide rod according to
The secondary metal cavity equipped with tetrafluoroethene column and internal filling epoxy resin.
2. the apparatus according to claim 1, characterized in that the electrode is adjustable high-voltage metal electrode, main body
For fan-shaped column structure, main body upper end is connect by helicitic texture with guide rod, the central angle of fan-shaped surface and target cable etc.
Effect insulating layer sample central angle is consistent, which is contacted by internal shield tight with sample inner surface, to
High pressure needed for specimen surface applies.
3. the apparatus according to claim 1, characterized in that the equivalent insulating layer sample of the target cable is flat by two
Row cylindrical shape die casting forms, and negative camber is bonded with adjustable high-voltage metal electrode lower surface, adjustable high-voltage metal electrode
The selection of specification is related with size of sample, and the selection of size of sample guarantees there is phase with the coaxial configuration cable insulation of stack pile
Same field distribution.
4. the apparatus according to claim 1, characterized in that the earthing mechanism include: earth plate and be located at its bottom
For detecting the piezoelectric transducer of the acoustical signal generated in cable insulation, acoustical signal is converted to by electricity by piezoelectric transducer
Signal and output to signal acquisition control system carry out record and analysis processing, display space charge measurements.
5. the apparatus according to claim 1, characterized in that the guide rod is equipped with the high pressure for isolated DC voltage
Capacitor.
6. a kind of electroacoustic pulse detecting method based on any of the above-described claim described device, which is characterized in that including following
Step:
Step 1, assembling test probe mechanism: tetrafluoroethene insulation sleeve column is set outside guide rod, fills asphalt mixtures modified by epoxy resin in metal cavity
The top and bottom for testing probe mechanism entirety are connected with metal top cover plate and insulation lower cover plate, by lower end of the guide rod by rouge respectively
There is the external thread structure Matching installation of internal thread structure and adjustable high-voltage metal electrode upper end protrusion and is embedded at lower cover plate
Middle part forms the top electrode of Integral movable;
Step 2, it prepares the equivalent insulation sample of target cable and is placed under adjustable high-voltage metal electrode, in metal electrode following table
Face is arranged shielded layer and wraps up, and is placed on earth plate after sample lower surface and shielded layer are fitted closely;
Step 3, the metal screw of even numbers quantity is passed through to the metal cover board two sides vertical core being placed on test probe mechanism and is led to
Cross the fixed test probe mechanism of nut and earth plate;The distance between upper and lower electrode is adjusted by nut, to adapt to different rule
The equivalent insulation sample of the target cable of lattice;
Step 4, DC high voltage is introduced into high-pressure metal electrode by conducting rod, then by piezoelectric transducer reception space charge
Acoustical signal, and convert electric signal for acoustical signal, output to signal acquisition control system.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201711467699.2A CN109991482A (en) | 2017-12-29 | 2017-12-29 | The simulation electrode device of cable insulation space charge detection |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201711467699.2A CN109991482A (en) | 2017-12-29 | 2017-12-29 | The simulation electrode device of cable insulation space charge detection |
Publications (1)
Publication Number | Publication Date |
---|---|
CN109991482A true CN109991482A (en) | 2019-07-09 |
Family
ID=67108521
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CN201711467699.2A Pending CN109991482A (en) | 2017-12-29 | 2017-12-29 | The simulation electrode device of cable insulation space charge detection |
Country Status (1)
Country | Link |
---|---|
CN (1) | CN109991482A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110398672A (en) * | 2019-07-31 | 2019-11-01 | 国网陕西省电力公司电力科学研究院 | A kind of sample structure and method measuring insulating materials ionization and charge transport parameters |
CN117890680A (en) * | 2024-01-16 | 2024-04-16 | 国网上海市电力公司 | Electrode device and measuring method for measuring insulating dielectric parameters of superconducting cable segment |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103105542A (en) * | 2013-01-17 | 2013-05-15 | 清华大学 | High voltage electrode device for pulsed electro-acoustic space charge measuring system |
CN103412244A (en) * | 2013-06-18 | 2013-11-27 | 国家电网公司 | Method for measuring space charge characteristics of HVDC XLPE cable under thermal-cold cycling |
CN103576005A (en) * | 2013-11-25 | 2014-02-12 | 上海交通大学 | System for measuring space charges in solid dielectrics under needle-board electrodes |
CN104297575A (en) * | 2014-10-14 | 2015-01-21 | 中国南方电网有限责任公司电网技术研究中心 | PEA space charge measurement system and method under full-size high-voltage direct current cable temperature control gradient |
CN104569630A (en) * | 2014-12-24 | 2015-04-29 | 上海交通大学 | Solid-liquid universal temperature control space charge measurement device based on pulse electroacoustic method |
CN105738711A (en) * | 2016-02-22 | 2016-07-06 | 清华大学 | High-voltage electrode device used for space charge measurement |
CN106249064A (en) * | 2016-07-12 | 2016-12-21 | 清华大学 | Insulation self-recovering type space charge measurement high-field electrode device |
-
2017
- 2017-12-29 CN CN201711467699.2A patent/CN109991482A/en active Pending
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103105542A (en) * | 2013-01-17 | 2013-05-15 | 清华大学 | High voltage electrode device for pulsed electro-acoustic space charge measuring system |
CN103412244A (en) * | 2013-06-18 | 2013-11-27 | 国家电网公司 | Method for measuring space charge characteristics of HVDC XLPE cable under thermal-cold cycling |
CN103576005A (en) * | 2013-11-25 | 2014-02-12 | 上海交通大学 | System for measuring space charges in solid dielectrics under needle-board electrodes |
CN104297575A (en) * | 2014-10-14 | 2015-01-21 | 中国南方电网有限责任公司电网技术研究中心 | PEA space charge measurement system and method under full-size high-voltage direct current cable temperature control gradient |
CN104569630A (en) * | 2014-12-24 | 2015-04-29 | 上海交通大学 | Solid-liquid universal temperature control space charge measurement device based on pulse electroacoustic method |
CN105738711A (en) * | 2016-02-22 | 2016-07-06 | 清华大学 | High-voltage electrode device used for space charge measurement |
CN106249064A (en) * | 2016-07-12 | 2016-12-21 | 清华大学 | Insulation self-recovering type space charge measurement high-field electrode device |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110398672A (en) * | 2019-07-31 | 2019-11-01 | 国网陕西省电力公司电力科学研究院 | A kind of sample structure and method measuring insulating materials ionization and charge transport parameters |
CN110398672B (en) * | 2019-07-31 | 2021-08-03 | 国网陕西省电力公司电力科学研究院 | Sample structure and method for measuring ionization and charge transfer parameters of insulating material |
CN117890680A (en) * | 2024-01-16 | 2024-04-16 | 国网上海市电力公司 | Electrode device and measuring method for measuring insulating dielectric parameters of superconducting cable segment |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN101706537B (en) | PEA space charge test device capable of testing conductive current | |
CN108089068B (en) | Composite flat plate sample three-dimensional space charge measuring device based on electroacoustic pulse method | |
CN101639502B (en) | System for automatically measuring charge distribution on surface of solid medium | |
CN100416283C (en) | Insulator charged detection instrument and its implement method | |
CN105911326B (en) | Conduction current-space charge combined measurement device | |
CN103105542B (en) | High voltage electrode device for pulsed electro-acoustic space charge measuring system | |
CN201945640U (en) | Polyacrylic ester (PEA) space charge tester capable of conducting current | |
CN101907659A (en) | Temperature controllable PEA space charge test device | |
CN105486927B (en) | A kind of measuring method of solid insulating material specific insulation | |
CN102998160B (en) | Cylindrical sample preparation device for measuring moisture content of green sand through capacitance method and method for measuring moisture content of green sand | |
CN103576005A (en) | System for measuring space charges in solid dielectrics under needle-board electrodes | |
CN105067439A (en) | Crack tip strain field sensor and measuring method thereof | |
CN204556089U (en) | A kind of GIS device vibration characteristics analoging detecting device | |
CN106443216B (en) | A kind of multi-layer solid composite dielectric material space charge measurement method | |
CN109991482A (en) | The simulation electrode device of cable insulation space charge detection | |
CN107677896B (en) | Same district timesharing conductance space charge measurement device based on ontology capacitance | |
CN206248765U (en) | A kind of hand-held High Frequency Current Sensor for Partial Discharge Detection | |
CN107290399B (en) | Transformer water content measuring device based on PDC/FDS medium response method | |
CN201935962U (en) | Temperature-controllable PEA (phenethylamine) space charge testing device | |
CN105486727B (en) | A kind of electrical impedance imaging electrode assembly for cement base hard material | |
CN110398517A (en) | Micro screw-type continuous penetration type TDR probe apparatus in situ | |
CN106645866A (en) | Conduction current and space charge synchronization measurement device | |
CN204462065U (en) | A kind of hand-held capacitance imaging probe | |
CN110441354A (en) | Plastic bonded explosive Density Distribution detection method based on capacitance chromatography imaging | |
CN206788252U (en) | The test device for insulation resistance of ceramic coating under a kind of pressure state |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PB01 | Publication | ||
PB01 | Publication | ||
SE01 | Entry into force of request for substantive examination | ||
SE01 | Entry into force of request for substantive examination | ||
RJ01 | Rejection of invention patent application after publication |
Application publication date: 20190709 |
|
RJ01 | Rejection of invention patent application after publication |