CN111939645A - Prevent hindering effectual sewage utilization device - Google Patents

Prevent hindering effectual sewage utilization device Download PDF

Info

Publication number
CN111939645A
CN111939645A CN202010741206.5A CN202010741206A CN111939645A CN 111939645 A CN111939645 A CN 111939645A CN 202010741206 A CN202010741206 A CN 202010741206A CN 111939645 A CN111939645 A CN 111939645A
Authority
CN
China
Prior art keywords
drum
sewage
installs
scraper
utilization device
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
Application number
CN202010741206.5A
Other languages
Chinese (zh)
Inventor
袁明华
张旭毅
金海峰
张超辉
田亚飞
翟志祥
杨显中
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wanjiang New Energy Group Co Ltd
Original Assignee
Wanjiang New Energy Group Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Wanjiang New Energy Group Co Ltd filed Critical Wanjiang New Energy Group Co Ltd
Priority to CN202010741206.5A priority Critical patent/CN111939645A/en
Publication of CN111939645A publication Critical patent/CN111939645A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D36/00Filter circuits or combinations of filters with other separating devices
    • B01D36/04Combinations of filters with settling tanks
    • B01D36/045Combination of filters with centrifugal separation devices
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D21/00Separation of suspended solid particles from liquids by sedimentation
    • B01D21/24Feed or discharge mechanisms for settling tanks
    • B01D21/245Discharge mechanisms for the sediments
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D29/00Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/62Regenerating the filter material in the filter
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D29/00Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/62Regenerating the filter material in the filter
    • B01D29/64Regenerating the filter material in the filter by scrapers, brushes, nozzles, or the like, acting on the cake side of the filtering element
    • B01D29/6469Regenerating the filter material in the filter by scrapers, brushes, nozzles, or the like, acting on the cake side of the filtering element scrapers
    • B01D29/6476Regenerating the filter material in the filter by scrapers, brushes, nozzles, or the like, acting on the cake side of the filtering element scrapers with a rotary movement with respect to the filtering element

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Filtration Of Liquid (AREA)

Abstract

The invention discloses a sewage utilization device with a good anti-blocking effect, and relates to the technical field of sewage source heat pumps. The water tank comprises a tank body, the jar body includes circular casing and conical shell, circular casing's lower fixed surface installs conical shell, circular casing trailing flank fixed mounting has the spiral inlet tube, conical shell lower fixed surface installs the blow off pipe, circular casing's upper surface installs sealed lid through fixed establishment, the last fixed surface of sealed lid installs the drum, the corresponding sealed lid fixed surface of drum installs the cartridge filter, the right side fixed surface of drum installs the outlet pipe, be provided with clearance mechanism on the drum. According to the invention, sewage in the tank body is subjected to a rotational flow dirt removing principle through the spiral water inlet pipe, so that the filter cartridge can be effectively prevented from being blocked due to dirt impurities and easily deposited solids, the filter cartridge and the drain pipe can be cleaned regularly, the filter cartridge and the drain pipe are effectively prevented from being blocked, and the use is convenient.

Description

Prevent hindering effectual sewage utilization device
Technical Field
The invention relates to the technical field of sewage source heat pumps, in particular to a sewage utilization device with a good anti-blocking effect.
Background
In the sewage source heat supply industry, the traditional sewage utilization mode is a sewage source + heat exchanger + heat pump technology, the temperature of tail water of direct heat exchange is generally 7 ℃, the temperature of the tail water of the sewage is generally designed to be 8 ℃, the temperature of inlet and outlet water designed by a general host is 12/5 ℃ due to heat exchange requirements and host characteristics, the average temperature of the heat pump host utilization is lower, the system energy efficiency is lower, if the temperature of the inlet and outlet water is increased, the temperature of return water of the sewage cannot be controlled, the maximum utilization of the sewage resources is difficult to realize, the standard design of the heat supply and return water temperature at the user side is recommended to be 50/40 ℃, the energy efficiency ratio of the heat pump host is relatively lower when the temperature difference is large, the operation working condition is poorer, and the actual operation condition is.
Because of containing a large amount of suspended solids in the sewage, easily heavy solid, if directly get into heat pump set, easily cause equipment to block, all need use when utilizing sewage and prevent hindering machine or heat exchanger, the current heat prevents on the existing market and hinders the device structure complicacy, need set up auxiliary motor and lead to cost and consumption height, and need often dismantle the clearance to the filter equipment who prevents hindering the device, the blow off pipe easily takes place blocking phenomenon, so provide one kind and prevent hindering effectual sewage utilization device in order to solve the above-mentioned problem that provides.
Disclosure of Invention
The invention provides a sewage utilization device with a good anti-blockage effect, which has the advantages of effectively preventing a filter cylinder from being blocked due to dirt impurities and easily-deposited solids by utilizing a rotational flow dirt removing principle, regularly cleaning the filter cylinder and a drain pipe, and effectively avoiding the filter cylinder and the drain pipe from being blocked, so as to solve the problems that a heat anti-blockage device is complicated in structure, high in cost and power consumption, and the filter device of the anti-blockage device is required to be frequently disassembled and cleaned, and the drain pipe is easily blocked.
In order to realize the purposes of effectively preventing the filter cartridge from being blocked by dirt and sundries and easily deposited solids by utilizing the rotational flow dirt removing principle, regularly cleaning the filter cartridge and the sewage discharge pipe and effectively avoiding the filter cartridge and the sewage discharge pipe from being blocked, the invention provides the following technical scheme: a sewage utilization device with good anti-blocking effect comprises a tank body, wherein the tank body comprises a circular shell and a conical shell, the conical shell is fixedly installed on the lower surface of the circular shell, a spiral water inlet pipe is fixedly installed on the rear side surface of the circular shell, a sewage discharge pipe is fixedly installed on the lower surface of the conical shell, a sealing cover is installed on the upper surface of the circular shell through a fixing mechanism, a cylinder is fixedly installed on the upper surface of the sealing cover and communicated with the tank body, a filter cylinder is fixedly installed on the lower surface of the sealing cover corresponding to the cylinder, a water outlet pipe is fixedly installed on the right side surface of the cylinder, a cleaning mechanism is arranged on the cylinder and comprises a motor, a rotating shaft, a fixing rod, a first scraper, a second scraper and a spiral material conveying piece, the motor is fixedly installed on the upper surface of the cylinder, and the pivot runs through the drum and inserts and locate the jar internally, lie in cartridge filter and the equal fixed mounting of downside in the pivot has the dead lever, be provided with first scraper with cartridge filter inner wall corresponding position on the dead lever, and downside dead lever upper surface and cartridge filter surface corresponding position are provided with the second scraper, have spiral material conveying piece with the corresponding position fixed mounting of blow off pipe in the pivot.
As a preferred technical scheme of the invention, the tank body is fixedly provided with support legs in a rectangular shape at the periphery, and the lower surfaces of the support legs are 20cm-30cm lower than the lower surface of the sewage discharge pipe.
As a preferred technical scheme of the present invention, the fixing mechanism includes a bolt bar and a lock nut, the bolt bar is inserted into the tank body and the seal cover, the lock nut is threadedly mounted on the bolt bar, and the tank body and the seal cover are locked and fixed by the lock nut.
As a preferred technical solution of the present invention, a sealing member is disposed at a position of the rotating shaft corresponding to the upper side wall of the cylinder.
As a preferred technical solution of the present invention, the first scraper is attached to an inner wall of the filter cartridge, and the second scraper is attached to an outer surface of the filter cartridge.
As a preferable technical scheme of the invention, through holes for the passing of the rotating shaft are formed in the positions, corresponding to the rotating shaft, on the lower side wall of the filter cylinder.
Compared with the prior art, the invention provides the sewage utilization device with good anti-blocking effect, which has the following beneficial effects:
1. this prevent hindering effectual sewage utilization device through setting up the spiral inlet tube, makes the internal sewage of entering jar form the whirl, utilizes the whirl scrubbing principle, can prevent effectively that sewage debris and the easy solid that sinks in the sewage from causing the cartridge filter to block up, prevents that the jam effect is better, and need not auxiliary assembly such as motors and makes sewage form the whirl, saves the cost, is convenient for maintain.
2. This prevent hindering effectual sewage utilization device drives the pivot rotation through setting up among the clearance mechanism motor, makes the pivot drive spiral feeding piece rotatory, accomplishes the blowdown work, and simultaneously at the in-process of blowdown, the dead lever drives first scraper and second scraper and clears up the inner wall and the surface of cartridge filter, effectively avoids cartridge filter and blow off pipe to be blockked up, need not regularly to carry out dismouting clearance, convenient to use to the cartridge filter.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a cross-sectional view of the present invention;
fig. 3 is a schematic view of the spiral water inlet pipe of the present invention.
In the figure: 1. a tank body; 101. a circular housing; 102. a conical housing; 2. a spiral water inlet pipe; 3. a blow-off pipe; 4. a fixing mechanism; 401. a bolt shank; 402. locking the nut; 5. a sealing cover; 6. a cylinder; 7. a filter cartridge; 8. a water outlet pipe; 9. a cleaning mechanism; 901. a motor; 902. a rotating shaft; 903. fixing the rod; 904. a first scraper; 905. a second scraper; 906. spirally feeding the material sheets; 10. supporting legs; 11. a seal member; 12. and a through hole.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-3, the invention discloses a sewage utilization device with good anti-blocking effect, which comprises a tank body 1, wherein the tank body 1 comprises a circular shell 101 and a conical shell 102, the conical shell 102 is fixedly arranged on the lower surface of the circular shell 101, a spiral water inlet pipe 2 is fixedly arranged on the rear side surface of the circular shell 101, a sewage discharge pipe 3 is fixedly arranged on the lower surface of the conical shell 102, a sealing cover 5 is arranged on the upper surface of the circular shell 101 through a fixing mechanism 4, a cylinder 6 is fixedly arranged on the upper surface of the sealing cover 5, the cylinder 6 is communicated with the tank body 1, a filter cylinder 7 is fixedly arranged on the lower surface of the sealing cover 5 corresponding to the cylinder 6, a water outlet pipe 8 is fixedly arranged on the right side surface of the cylinder 6, a cleaning mechanism 9 is arranged on the cylinder 6, and the cleaning mechanism 9 comprises a motor, First scraper 904, second scraper 905 and spiral material feeding piece 906, motor 901 fixed mounting is in 6 upper surfaces of drum, fixed mounting has pivot 902 on the output shaft of motor 901, and pivot 902 runs through drum 6 and inserts and locate jar body 1 in, the equal fixed mounting of downside has dead lever 903 in cartridge filter 7 on pivot 902, be provided with first scraper 904 with the corresponding position of 7 inner walls of cartridge filter on the dead lever 903, and downside dead lever 903 upper surface and the corresponding position of 7 surface of cartridge filter are provided with second scraper 905, fixed mounting has spiral material feeding piece 906 with the corresponding position of blow off pipe 3 on the pivot 902.
Specifically, the tank body 1 is fixedly provided with support legs 10 in a rectangular shape at the periphery, and the lower surfaces of the support legs 10 are lower than the lower surface of the sewage discharge pipe 3 by 20cm-30 cm.
In this embodiment, the support legs 10 facilitate the installation of the tank 1 and stabilize the placement thereof.
Specifically, the fixing mechanism 4 includes a bolt bar 401 and a lock nut 402, the bolt bar 401 is inserted into the tank 1 and the seal cover 5, the lock nut 402 is threadedly mounted on the bolt bar 401, and the lock nut 402 locks and fixes the tank 1 and the seal cover 5.
In this embodiment, the bolt 401 is inserted into the edge of the tank 1 and the sealing cover 5, and the locking nut 402 is threadedly mounted on the bolt 401, so that the tank 1 and the sealing cover 5 are attached to each other and locked and fixed, and the sealing cover 5 is detachable.
Specifically, the sealing member 11 is disposed at a position of the rotating shaft 902 corresponding to an upper side wall of the cylinder 6.
In this embodiment, the sealing member 11 provides a better sealing effect between the rotating shaft 902 and the upper sidewall of the cylinder 6, and is not easy to overflow sewage.
Specifically, the first scraper 904 is attached to the inner wall of the filter cartridge 7, and the second scraper 905 is attached to the outer surface of the filter cartridge 7.
In this embodiment, the first scraper 904 can clean up the contaminants on the inner wall of the filter cartridge 7, and the second scraper 905 can clean up the contaminants adhered to the outer surface of the filter cartridge 7.
Specifically, a through hole 12 through which the rotating shaft 902 passes is formed in a position on the lower side wall of the filter cartridge 7 corresponding to the rotating shaft 902.
In this embodiment, the through hole 12 facilitates the rotation shaft 902 to pass through the filter cartridge 7, thereby facilitating the installation of the rotation shaft 902.
The working principle and the using process of the invention are as follows: when the device is used, external sewage is enabled to enter the tank body 1 in a rotational flow state through the spiral water inlet pipe 2, rotational flow is formed in the circular shell 101, the sewage in the tank body 1 utilizes the rotational flow dirt removing principle to enable easily-deposited solid and dirt impurities to enter the conical shell 102 at the lower part of the tank body 1, the dirt impurities and the easily-deposited solid in the sewage can be effectively prevented from being adhered to the filter cartridge 7, the problem that the filter cartridge 7 is blocked is avoided, the sewage filtered by the filter cartridge 7 flows into the water outlet pipe 8 through the cylinder 6 and is discharged through the water outlet pipe 8, when the sediment in the conical shell 102 needs to be cleaned regularly, the motor 901 in the cleaning mechanism 9 drives the rotating shaft 902 to rotate, the rotating shaft 902 drives the spiral material feeding piece 906 to rotate, the dirt discharge work is completed, the dirt discharge pipe 3 is prevented from being blocked, meanwhile, the rotating shaft 902 drives the fixing rod 903 to rotate in the dirt discharge process, and the, make first scraper 904 to the inner wall of cartridge filter 7, second scraper 905 clears up the surface of cartridge filter 7, effectively avoids cartridge filter 7 and blow off pipe 3 to be blockked up convenient to use.
To sum up, this prevent hindering effectual sewage utilization device makes jar internal sewage utilize the whirl scrubbing principle through spiral inlet tube 2, can prevent effectively that dirty debris and the easy solid that sinks from causing cartridge filter 7 to block up, and can regularly clear up cartridge filter 7 and blow off pipe 3, effectively avoids cartridge filter 7 and blow off pipe 3 to be blockked up convenient to use.
It should be noted that, in this document, terms such as "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (6)

1. The utility model provides a prevent hindering effectual sewage utilization device, includes jar body (1), its characterized in that: the utility model discloses a cleaning tank for the sewage treatment, including jar body (1) including circular casing (101) and conical shell (102), the lower fixed surface of circular casing (101) installs conical shell (102), circular casing (101) trailing flank fixed mounting has spiral inlet tube (2), conical shell (102) lower fixed surface installs blow off pipe (3), sealed lid (5) are installed through fixed establishment (4) to the upper surface of circular casing (101), the last fixed surface of sealed lid (5) installs drum (6), and drum (6) are linked together with jar body (1), the corresponding sealed lid (5) lower fixed surface of drum (6) installs cartridge filter (7), the right side fixed surface of drum (6) installs outlet pipe (8), be provided with clearance mechanism (9) on drum (6), clearance mechanism (9) include motor (901), Pivot (902), dead lever (903), first scraper (904), second scraper (905) and spiral send tablet (906), motor (901) fixed mounting is in drum (6) upper surface, fixed mounting has pivot (902) on the output shaft of motor (901), and pivot (902) run through drum (6) and insert and locate jar body (1) in, lie in cartridge filter (7) on pivot (902) and the equal fixed mounting of downside has dead lever (903), be provided with first scraper (904) with cartridge filter (7) inner wall corresponding position on dead lever (903), and downside dead lever (903) upper surface and cartridge filter (7) surface corresponding position are provided with second scraper (905), with drain (3) corresponding position fixed mounting has spiral to send tablet (906) in pivot (902).
2. The sewage utilization device with good anti-blocking effect according to claim 1, characterized in that: the tank body (1) is rectangular and fixedly provided with supporting legs (10), and the lower surfaces of the supporting legs (10) are lower than the lower surface of the sewage discharge pipe (3) by 20cm-30 cm.
3. The sewage utilization device with good anti-blocking effect according to claim 1, characterized in that: the fixing mechanism (4) comprises a bolt rod (401) and a locking nut (402), the bolt rod (401) is inserted into the tank body (1) and the sealing cover (5), the locking nut (402) is installed on the bolt rod (401) in a threaded mode, and the tank body (1) and the sealing cover (5) are locked and fixed through the locking nut (402).
4. The sewage utilization device with good anti-blocking effect according to claim 1, characterized in that: and a sealing element (11) is arranged at the position of the rotating shaft (902) corresponding to the upper side wall of the cylinder (6).
5. The sewage utilization device with good anti-blocking effect according to claim 1, characterized in that: the first scraper (904) is attached to the inner wall of the filter cylinder (7), and the second scraper (905) is attached to the outer surface of the filter cylinder (7).
6. The sewage utilization device with good anti-blocking effect according to claim 1, characterized in that: and through holes (12) through which the rotating shaft (902) passes are formed in the positions, corresponding to the rotating shaft (902), on the lower side wall of the filter cartridge (7).
CN202010741206.5A 2020-07-29 2020-07-29 Prevent hindering effectual sewage utilization device Pending CN111939645A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010741206.5A CN111939645A (en) 2020-07-29 2020-07-29 Prevent hindering effectual sewage utilization device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010741206.5A CN111939645A (en) 2020-07-29 2020-07-29 Prevent hindering effectual sewage utilization device

Publications (1)

Publication Number Publication Date
CN111939645A true CN111939645A (en) 2020-11-17

Family

ID=73338367

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010741206.5A Pending CN111939645A (en) 2020-07-29 2020-07-29 Prevent hindering effectual sewage utilization device

Country Status (1)

Country Link
CN (1) CN111939645A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113274791A (en) * 2021-04-13 2021-08-20 梁文杰 Pressure boost filtration equipment for building site

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140246387A1 (en) * 2013-03-04 2014-09-04 Met Weld International Llc Multi-purpose self-cleaning filter system
CN104128268A (en) * 2014-08-01 2014-11-05 尤云祥 Vertical all-around cyclone dirt remover
CN104302374A (en) * 2012-05-17 2015-01-21 陶氏环球技术有限责任公司 Hydroclone with inlet flow shield
CN109126279A (en) * 2018-10-15 2019-01-04 伍超群 A kind of medical waste water filter device
CN210674397U (en) * 2019-08-12 2020-06-05 昆山卓滤净化设备有限公司 Industrial wastewater filtering device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104302374A (en) * 2012-05-17 2015-01-21 陶氏环球技术有限责任公司 Hydroclone with inlet flow shield
US20140246387A1 (en) * 2013-03-04 2014-09-04 Met Weld International Llc Multi-purpose self-cleaning filter system
CN104128268A (en) * 2014-08-01 2014-11-05 尤云祥 Vertical all-around cyclone dirt remover
CN109126279A (en) * 2018-10-15 2019-01-04 伍超群 A kind of medical waste water filter device
CN210674397U (en) * 2019-08-12 2020-06-05 昆山卓滤净化设备有限公司 Industrial wastewater filtering device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113274791A (en) * 2021-04-13 2021-08-20 梁文杰 Pressure boost filtration equipment for building site
CN113274791B (en) * 2021-04-13 2022-11-22 安徽华章工程管理有限公司 Pressure boost filtration equipment for building site

Similar Documents

Publication Publication Date Title
CN111544960B (en) Treatment device for recycling domestic wastewater
CN111939645A (en) Prevent hindering effectual sewage utilization device
CN111517434B (en) Water works charge device
CN211035473U (en) Advanced water supply treatment reaction device
CN209501131U (en) Without motor-driven rotation type wind smoke pipeline filter device
CN211400907U (en) Waste water waste heat recovery system of recycling of printing and dyeing mill
CN212016924U (en) Particle filtering device for sewage treatment
CN211536754U (en) High-efficient type waste water purification unit
CN213899280U (en) Anti-blocking mechanism for water inlet end of sewage pump
CN220758142U (en) Phosphating solution purifying device
CN212982654U (en) Wastewater purification device for wastewater treatment
CN220090590U (en) Device for cleaning mud and sand at bottom of pond body
CN218709701U (en) Effluent treatment plant for environmental engineering
CN217287197U (en) Triple-effect evaporator for sewage treatment
CN214130529U (en) Filtering device with rotational flow backflushing device
CN217230410U (en) Sewage interception and purification device for water pollution control
CN218374352U (en) Sewage pipeline anti-blocking device for wastewater treatment
CN210945151U (en) Graphite production stores up dirty clarification plant
CN220026258U (en) Sewage treatment equipment convenient to maintain
CN214653992U (en) Sludge discharge device for sewage treatment
CN220460074U (en) High-efficiency filter for filtering water paint impurities
CN215195741U (en) Rotary micro-filter
CN216824827U (en) Anti-blocking vertical reboiler
CN211367313U (en) Novel MBR membrane sewage treatment device
CN218590189U (en) Ultrafiltration and reverse osmosis integrated water treatment device

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: 20201117

RJ01 Rejection of invention patent application after publication