CN208348164U - The second level axial flow blower of efficient anti-surging - Google Patents
The second level axial flow blower of efficient anti-surging Download PDFInfo
- Publication number
- CN208348164U CN208348164U CN201820493357.1U CN201820493357U CN208348164U CN 208348164 U CN208348164 U CN 208348164U CN 201820493357 U CN201820493357 U CN 201820493357U CN 208348164 U CN208348164 U CN 208348164U
- Authority
- CN
- China
- Prior art keywords
- stage impeller
- inner cylinder
- tooth
- surge
- rectangular saw
- 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.)
- Active
Links
- 238000009434 installation Methods 0.000 claims abstract description 10
- 241001646071 Prioneris Species 0.000 claims description 52
- 238000009826 distribution Methods 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 4
- UJCHIZDEQZMODR-BYPYZUCNSA-N (2r)-2-acetamido-3-sulfanylpropanamide Chemical compound CC(=O)N[C@@H](CS)C(N)=O UJCHIZDEQZMODR-BYPYZUCNSA-N 0.000 claims description 3
- 241001669680 Dormitator maculatus Species 0.000 claims description 3
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 claims description 3
- 239000004744 fabric Substances 0.000 claims description 2
- 230000005611 electricity Effects 0.000 claims 1
- 238000003466 welding Methods 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 7
- 238000010992 reflux Methods 0.000 abstract description 2
- 238000007789 sealing Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000009423 ventilation Methods 0.000 description 3
- 230000001088 anti-asthma Effects 0.000 description 2
- 239000000924 antiasthmatic agent Substances 0.000 description 2
- 238000004378 air conditioning Methods 0.000 description 1
- 208000006673 asthma Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 235000013339 cereals Nutrition 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Landscapes
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The utility model discloses the second level axial flow blowers of efficient anti-surging.Existing axial flow blower is easy to appear surge phenomenon.The utility model includes anti-surge installation, one stage impeller, guide vane, blower outer cylinder, sencond stage impeller, Dual-output shaft motor and inner cylinder;Anti-surge installation includes guide shell, collector ring and anti-surge outer cylinder;Labyrinth seal structure is equipped between the wheel hub of the one stage impeller end face opposite with inner cylinder, between the wheel hub of sencond stage impeller and the opposite end face of inner cylinder.The utility model is rectified air-flow through the small deflector of several aerofoil profiles and collector ring by anti-surge installation again, is prevented the reflux of air-flow, is not only avoided the generation of blower surge phenomenon, while also improving the efficiency and range of operation of blower;By adding labyrinth seal structure in the gap of wheel hub and inner cylinder, very strong throttle effect is generated, non-contact seals are played the role of, improves the stability of air-flow at impeller outlet, reduces the leakage rate of air-flow, reduces volumetric loss, improves efficiency.
Description
Technical field
The utility model relates to one kind efficiently, energy conservation, anti-surging axial flow fan, in particular to and the two of a kind of efficient anti-surging
Grade axial flow blower.
Background technique
Axial flow blower is to improve gas pressure by the mechanical energy of input and supply gas side by side the machinery of body.It is widely used in work
Ventilation, dust discharge and the cooling of factory, mine, tunnel, cooling tower, vehicle, ship and building, boiler, industrial furnace ventilation and
Air inducing, cooling and ventilation in the apparatus of air conditioning, domestic electric appliance and are selected and recommended, wind-tunnel wind regime and air cushion at the drying of cereal
Inflation propulsion of ship etc., has very important application in national economy every profession and trade.It is more with the continuous improvement of wind industrial level
The application of grade axial flow blower is also more and more extensive.But due to the Aerodynamic Characteristics of axial flow blower itself, when blower works, when
Air quantity reduces to a certain extent, and when import and outlet pressure reach surge pressure ratio, blower just will appear surge phenomenon,
This phenomenon seriously affects the normal use of axial flow blower, so that relative vibration between each component of axial flow blower, and noise is generated, sternly
Ghost image rings the service life of blower.It can be seen that the surge phenomenon for solving axial flow blower is held the balance in manufacturing and designing.
Summary of the invention
The purpose of this utility model is that surge phenomenon easily occurs existing for existing second level axial flow blower, provides one kind
The second level axial flow blower of efficient anti-surging.
The utility model includes anti-surge installation, one stage impeller, guide vane, blower outer cylinder, sencond stage impeller, Dual-output shaft motor
And inner cylinder;The anti-surge installation includes guide shell, collector ring and anti-surge outer cylinder;Anti-surge outer cylinder passes through with blower outer cylinder
It is bolted;Collector ring is arranged in anti-surge outer cylinder, and welds with anti-surge outer cylinder;The guide shell is by outer barrel, the wing
The small deflector of type and inner cylinder composition;Outer barrel and inner cylinder are welded with collector ring arrival end end face, and the internal diameter of outer barrel is small
In the internal diameter of collector ring;The small deflector of several aerofoil profiles being evenly distributed, the small water conservancy diversion of aerofoil profile are equipped between outer barrel and inner cylinder
The inside and outside end of plate is respectively welded with inner cylinder outer wall and outer barrel inner wall;7~17 guide vanes are circumferentially distributed along inner cylinder, in guide vane,
It is welded respectively with inner tank theca and blower outer tube inner wall outer end;The pedestal of Dual-output shaft motor is fixed on inner cylinder inner wall;Level-one
The both ends output shaft of impeller and sencond stage impeller and Dual-output shaft motor is fixed by axle sleeve respectively;One stage impeller and sencond stage impeller are set
Set in guide vane two sides, and one stage impeller than sencond stage impeller close to collector ring;The wheel hub of the one stage impeller end face opposite with inner cylinder it
Between, the wheel hub of sencond stage impeller be equipped with labyrinth seal structure between the end face opposite with inner cylinder;
The labyrinth seal structure is made of the first rectangular saw-tooth and the second rectangular saw-tooth;Multiple first rectangular saw-tooths etc.
Away from being arranged on the wheel hub end face of one stage impeller or sencond stage impeller;Multiple second rectangular saw-tooths are placed equidistant on the inner cylinder, and phase
The spacing of adjacent second rectangular saw-tooth is equal to the spacing of adjacent first rectangular saw-tooth;The height of first rectangular saw-tooth and the second rectangular saw-tooth
Degree is d4, and width is d3, and d3 is the 1/5~1/3 of d4;The quantity of first rectangular saw-tooth be 4~7, two neighboring first
One the second rectangular saw-tooth is set between rectangular saw-tooth;Between the wheel hub of the one stage impeller or sencond stage impeller end face opposite with inner cylinder
Spacing be 10mm, d4 value be the spacing 60%~80%;The wheel of second rectangular saw-tooth and one stage impeller or sencond stage impeller
Spacing between the opposite end face of hub is equal to the spacing between the first rectangular saw-tooth end face opposite with inner cylinder;First rectangular saw-tooth
Spacing between the second rectangular saw-tooth side is the 1/8~1/5 of d4.
The Dual-output shaft motor is threephase asynchronous machine, rated speed 720r/min, rated power 4KW.
The guide vane be circular arc airfoil blade, guide vane with a thickness of 2~4mm.
Blade on the one stage impeller be by etc. circular rectors Isolated Airfoil method design airfoil fan, vane thickness distribution
Identical as NACA 4-digit number profile thickness distribution, suffered pressure is radially constant, and the blade relative thickness of one stage impeller is
10%~15%, quantity is 5~9, and blade tip clearance is the 1%~2% of blade height.
The utility model has the beneficial effects that
1, the utility model is rectified air-flow through the small deflector of several aerofoil profiles and collector ring by anti-surge installation again,
The reflux for preventing air-flow, not only avoids the generation of blower surge phenomenon, while also improving the efficiency and range of operation of blower;
2, the utility model generates very strong throttle effect by adding labyrinth seal structure in the gap of wheel hub and inner cylinder,
Play the role of non-contact seals, improve the stability of air-flow at impeller outlet, reduce the leakage rate of air-flow, reduces volume damage
It loses, improves efficiency;
3, the utility model structure it is simple, it is novel in design, practical, ensure second level axial flow blower efficiently, safety fortune
Row preferably eliminates the generation of surge phenomenon, and relatively original traditional fan efficiency is higher, and noise is lower, is more energy-saving and environmentally friendly.
Detailed description of the invention
Fig. 1 is the cross-sectional view of the utility model blower;
Fig. 2 is the A-A cross-sectional view of Fig. 1;
Fig. 3 is the enlarged drawing of part B in Fig. 1;
Fig. 4 is the guide vane structure figure of the utility model;
In figure: 1, guide shell, 1-1, outer barrel, the small deflector of 1-2, aerofoil profile, 1-3, inner cylinder, 2, collector ring, 3, anti-asthma
Shake outer cylinder, 4, one stage impeller, 5, guide vane, 6, blower outer cylinder, 7, sencond stage impeller, 8, Dual-output shaft motor, 9, inner cylinder.
Specific embodiment
The utility model is described in further detail with reference to the accompanying drawings and embodiments.
As illustrated in fig. 1 and 2, the second level axial flow blower of efficient anti-surging, including anti-surge installation, one stage impeller 4, guide vane 5,
Blower outer cylinder 6, sencond stage impeller 7, Dual-output shaft motor 8 and inner cylinder 9;Anti-surge installation includes guide shell 1, collector ring 2 and anti-asthma
Shake outer cylinder 3;Anti-surge outer cylinder 3 is bolted with blower outer cylinder 6;Collector ring 2 is arranged in anti-surge outer cylinder 3, and with it is anti-
Surge outer cylinder 3 welds;Guide shell 1 is made of outer barrel 1-1, aerofoil profile small deflector 1-2 and inner cylinder 1-3;Outer barrel 1-1 and interior
Cylinder 1-3 is welded with 2 arrival end end face of collector ring, and the internal diameter of outer barrel 1-1 is less than the internal diameter of collector ring 2;Outer barrel 1-1 and
Be equipped with the small deflector 1-2 of several aerofoil profiles that is evenly distributed between inner cylinder 1-3, the inside and outside end of the small deflector 1-2 of aerofoil profile with it is interior
Cylinder 1-3 outer wall and outer barrel 1-1 inner wall are respectively welded;The small deflector of aerofoil profile passes through collector ring weight after can blending vortical flow
New rectification, reduces direct impact of the whirlpool to two impellers;7~17 (being 9 in the present embodiment) guide vanes are along circumferential point of inner cylinder 9
Cloth, the inside and outside end of guide vane 5 are welded with 9 outer wall of inner cylinder and 6 inner wall of blower outer cylinder respectively;In the pedestal of Dual-output shaft motor 8 is fixed on
On 9 inner walls of cylinder, wherein Dual-output shaft motor 8 is threephase asynchronous machine, rated speed 720r/min, rated power 4KW;
The hub centre of one stage impeller 4 and sencond stage impeller 7 and the both ends output shaft of Dual-output shaft motor 8 are fixed by axle sleeve respectively;One
Grade impeller 4 and the setting of sencond stage impeller 7 in 5 two sides of guide vane, and one stage impeller 4 than sencond stage impeller 7 close to collector ring 2;One stage impeller 4
The wheel hub end face opposite with inner cylinder between, between the wheel hub of sencond stage impeller 7 and the opposite end face of inner cylinder 9 be equipped with labyrinth seal
Structure;One stage impeller 4 and sencond stage impeller 7 are driven dynamic pressure and the static pressure that gas is improved to air work by Dual-output shaft motor 8;
Blade on one stage impeller 4 be by etc. circular rectors Isolated Airfoil method design airfoil fan, vane thickness distribution with NACA tetra-
Digital profile thickness distribution is identical, and suffered pressure is radially constant, and the blade relative thickness of one stage impeller 4 takes in the present embodiment
10%, quantity is 6, and blade tip clearance is the 2% of blade height.
As shown in figure 3, labyrinth seal structure is made of the first rectangular saw-tooth and the second rectangular saw-tooth;Multiple first rectangle saws
Tooth is placed equidistant on the wheel hub end face of one stage impeller 4 or sencond stage impeller 7;Multiple second rectangular saw-tooths are placed equidistant in inner cylinder
On, and the spacing of adjacent second rectangular saw-tooth is equal to the spacing of adjacent first rectangular saw-tooth;First rectangular saw-tooth and the second rectangle
The height of sawtooth is d4, and width is d3,1/5~1/3 (being 1/4 in the present embodiment) that d3 is d4;First rectangular saw-tooth
Quantity is 4~7 (they being 5 in the present embodiment), and second rectangular saw-tooth is arranged between two neighboring first rectangular saw-tooth, because
This, more one of the quantity of the first rectangular saw-tooth than the second rectangular saw-tooth;The wheel hub of one stage impeller 4 or sencond stage impeller 7 and inner cylinder 9
Spacing between opposite end face is 10mm, and d4 value is 60%~80% (being 70% in the present embodiment) of the spacing;Second
Spacing between the rectangular saw-tooth end face opposite with the wheel hub of one stage impeller 4 or sencond stage impeller 7 is d1, the first rectangular saw-tooth with it is interior
Spacing between 9 opposite end faces of cylinder is d2, d1=d2;Spacing between first rectangular saw-tooth and the second rectangular saw-tooth side is
1/8~1/5 (being 1/7 in the present embodiment) of d4.
As shown in figure 4, guide vane is circular arc airfoil blade, which does not reverse along radial, the thickness of guide vane
Degree is 2~4mm (being 3mm in the present embodiment).
Vortical flow is equably blended, is decomposed by the small deflector 1-2 of the aerofoil profile of guide shell 1 in the utility model, by whirlpool
The front and back pressure difference stress that air-flow generates the blade of one stage impeller 4 is minimized, and acts on the injustice on the blade of one stage impeller 4
Weighing apparatus power also greatly reduces.Then collector ring 2 obstructs these vortical flows after blending, and avoids the vortical flow after blending to be more than
30 ° of flow inlet angle rapidly enters the blade inlet edge of one stage impeller 4, using the smooth air-flow of longer one section of rectification length, eliminates asthma
The harm and air turbulence phenomenon that the backflow phenomenon that shakes generates the blade of one stage impeller 4;The small deflector 1-2 of aerofoil profile and collector ring 2
The function and effect of one stage impeller 4 can also be generated with the function and effect of same property in sencond stage impeller 7.One stage impeller 4 or second level
Labyrinth seal structure between the wheel hub of impeller 7 end face opposite with inner cylinder can generate very strong throttle effect, play non-contact
The effect of sealing improves the stability of one stage impeller 4 or 7 exit air-flow of sencond stage impeller, reduces the leakage rate of air-flow, reduces and holds
Product loss, improves efficiency.The inherent mechanism of labyrinth seal structure is air-flow through the first rectangular saw-tooth and the second rectangular saw-tooth side
Between sealing cavity after enter between the second rectangular saw-tooth end face opposite with wheel hub or the first rectangular saw-tooth and inner cylinder 9 it is opposite
End face between toroidal cavity, expansion suddenly and generate strong whirlpool, make most of kinetic energy of air-flow be converted into heat and
It loses, only fraction kinetic energy enters the sealing cavity between the first rectangular saw-tooth of next stage and the second rectangular saw-tooth side,
It repeats rear gas pressure step by step to be gradually reduced, to achieve the effect that sealing.The utility model keeps second level axial flow blower effectively anti-
The only generation of surge phenomenon, so that more efficient, noise is lower, is more energy-saving and environmentally friendly.
Claims (4)
1. the second level axial flow blower of efficient anti-surging, including anti-surge installation, one stage impeller, guide vane, blower outer cylinder, second level leaf
Wheel, Dual-output shaft motor and inner cylinder, it is characterised in that: the anti-surge installation includes outside guide shell, collector ring and anti-surge
Cylinder;Anti-surge outer cylinder is bolted with blower outer cylinder;Collector ring is arranged in anti-surge outer cylinder, and welds with anti-surge outer cylinder
It connects;The guide shell is made of outer barrel, the small deflector of aerofoil profile and inner cylinder;Outer barrel and inner cylinder with collector ring entrance
End face welding is held, the internal diameter of outer barrel is less than the internal diameter of collector ring;It is evenly distributed if being equipped between outer barrel and inner cylinder
The dry small deflector of aerofoil profile, inside and outside end and the inner cylinder outer wall and outer barrel inner wall of the small deflector of aerofoil profile are respectively welded;7~17
Guide vane is circumferentially distributed along inner cylinder, and the inside and outside end of guide vane is welded with inner tank theca and blower outer tube inner wall respectively;Dual-output shaft motor
Pedestal is fixed on inner cylinder inner wall;The both ends output shaft of one stage impeller and sencond stage impeller and Dual-output shaft motor passes through axle sleeve respectively
It is fixed;One stage impeller and sencond stage impeller setting in guide vane two sides, and one stage impeller than sencond stage impeller close to collector ring;One stage impeller
The wheel hub end face opposite with inner cylinder between, between the wheel hub of sencond stage impeller and the opposite end face of inner cylinder be equipped with labyrinth seal knot
Structure;
The labyrinth seal structure is made of the first rectangular saw-tooth and the second rectangular saw-tooth;Multiple first rectangular saw-tooths are equidistantly set
It sets on the wheel hub end face of one stage impeller or sencond stage impeller;Multiple second rectangular saw-tooths are placed equidistant on the inner cylinder, and adjacent
The spacing of two rectangular saw-tooths is equal to the spacing of adjacent first rectangular saw-tooth;The height of first rectangular saw-tooth and the second rectangular saw-tooth is equal
For d4, width is d3, and d3 is the 1/5~1/3 of d4;The quantity of first rectangular saw-tooth is 4~7, two neighboring first rectangle
One the second rectangular saw-tooth is set between sawtooth;Between between the wheel hub of the one stage impeller or sencond stage impeller end face opposite with inner cylinder
Away from for 10mm, d4 value is the 60%~80% of the spacing;The wheel hub phase of second rectangular saw-tooth and one stage impeller or sencond stage impeller
Pair end face between spacing be equal to the spacing between the first rectangular saw-tooth end face opposite with inner cylinder;First rectangular saw-tooth and
Spacing between two rectangular saw-tooth sides is the 1/8~1/5 of d4.
2. the second level axial flow blower of efficient anti-surging according to claim 1, it is characterised in that: the double output shaft electricity
Machine is threephase asynchronous machine, rated speed 720r/min, rated power 4KW.
3. the second level axial flow blower of efficient anti-surging according to claim 1, it is characterised in that: the guide vane is circular arc
Airfoil fan, guide vane with a thickness of 2~4mm.
4. the second level axial flow blower of efficient anti-surging according to claim 1, it is characterised in that: on the one stage impeller
Blade be by etc. the design of circular rectors Isolated Airfoil method airfoil fan, vane thickness distribution and NACA 4-digit number profile thickness point
Cloth is identical, and suffered pressure is radially constant, and the blade relative thickness of one stage impeller is 10%~15%, and quantity is 5~9, leaf
Push up 1%~2% that gap is blade height.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201820493357.1U CN208348164U (en) | 2018-04-09 | 2018-04-09 | The second level axial flow blower of efficient anti-surging |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201820493357.1U CN208348164U (en) | 2018-04-09 | 2018-04-09 | The second level axial flow blower of efficient anti-surging |
Publications (1)
Publication Number | Publication Date |
---|---|
CN208348164U true CN208348164U (en) | 2019-01-08 |
Family
ID=64884832
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CN201820493357.1U Active CN208348164U (en) | 2018-04-09 | 2018-04-09 | The second level axial flow blower of efficient anti-surging |
Country Status (1)
Country | Link |
---|---|
CN (1) | CN208348164U (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108425889A (en) * | 2018-04-09 | 2018-08-21 | 浙江理工大学上虞工业技术研究院有限公司 | The two level axial flow blower and its anti-asthma method of slight of efficient anti-surging |
CN111894874A (en) * | 2020-08-10 | 2020-11-06 | 绍兴智新机电科技有限公司 | Low-noise fan stable in operation |
CN111927795A (en) * | 2020-08-20 | 2020-11-13 | 绍兴智新机电科技有限公司 | Two-stage axial flow low-noise fan |
-
2018
- 2018-04-09 CN CN201820493357.1U patent/CN208348164U/en active Active
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108425889A (en) * | 2018-04-09 | 2018-08-21 | 浙江理工大学上虞工业技术研究院有限公司 | The two level axial flow blower and its anti-asthma method of slight of efficient anti-surging |
CN111894874A (en) * | 2020-08-10 | 2020-11-06 | 绍兴智新机电科技有限公司 | Low-noise fan stable in operation |
CN111894874B (en) * | 2020-08-10 | 2021-10-22 | 绍兴智新机电科技有限公司 | Low-noise fan stable in operation |
CN111927795A (en) * | 2020-08-20 | 2020-11-13 | 绍兴智新机电科技有限公司 | Two-stage axial flow low-noise fan |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN208348164U (en) | The second level axial flow blower of efficient anti-surging | |
CN105736425B (en) | A kind of blade has the axial flow blower of bionical trailing edge with aerofoil profile deflector and stator | |
CN206175256U (en) | High -efficient axial fan | |
CN104653496B (en) | A kind of single double suction centrifugal ventilator with adjustable | |
CN105756996B (en) | A kind of blade suction surface has the axial flow blower of turbo-charger set structure and leaf top fluting | |
CN104632700B (en) | Dual-impeller device of centrifugal blower | |
CN209569902U (en) | Gas water heater | |
CN110374925B (en) | Double-layer current collector and mixed flow fan assembled with same | |
CN210564777U (en) | Miniature turboprop engine with double-sided composite impeller | |
CN108425889A (en) | The two level axial flow blower and its anti-asthma method of slight of efficient anti-surging | |
CN105756976A (en) | Direct connection mixed flow fan | |
CN110359964A (en) | A kind of power turbine of gas turbine | |
CN104653515A (en) | Double-suction type centrifugal ventilation fan | |
CN211398034U (en) | Impeller of energy-saving centrifugal ventilator | |
CN204692190U (en) | A kind of vane diffuser with deviated splitter vane | |
CN209180085U (en) | A kind of flow-guiding type air intake centrifugal blower | |
CN104632699B (en) | A kind of centrifugal fan bilobed wheel | |
CN203453115U (en) | Backward centrifugal wind wheel | |
CN104454331A (en) | Low-speed wind double ejector mixer | |
CN113883099B (en) | High-efficient wind-guiding structure and fan | |
CN110159597A (en) | A kind of cooling device and axial flow blower for steel mill's high-speed rod air-cooled line | |
CN206129652U (en) | High efficiency low noise centrifugal fan | |
CN205172997U (en) | Efflux themogenesis high -temperature hot -air blower | |
CN204572334U (en) | The dual mixer-ejector of a kind of low speed wind power | |
CN205207221U (en) | Fan |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
GR01 | Patent grant | ||
GR01 | Patent grant |