Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide an ozone catalytic oxidation tower type reaction device, which leads a gas-liquid mixture formed by ozone and sewage to fill a stirring cavity, and fully stirs and mixes the gas-liquid mixture, thereby improving the mixing efficiency and mixing effect of the ozone and the sewage.
The above object of the present invention is achieved by the following technical solutions:
an ozone catalytic oxidation tower type reaction device comprises a tower body, a tower cover and an ozone generator, wherein a liquid inlet pipe and an aeration disc communicated with the ozone generator are arranged at the lower part of the tower body, a liquid outlet pipe is arranged at the upper part of the tower body, the liquid outlet pipe is communicated with a water outlet pipe through a tail gas treatment device, a partition plate is arranged in the tower body, the partition plate divides an inner cavity of the tower body into a transmission cavity and a mixing cavity from top to bottom, an annular blocking ring plate extends inwards from the lower part of the inner wall of the mixing cavity, the liquid inlet pipe and the aeration disc are both positioned below the blocking ring plate, a first drainage tube with an upper opening extends upwards from the inner side of the blocking ring plate, and a first drainage channel is formed in the inner cavity of the first drainage tube; a second drainage cylinder which is positioned above the blocking annular plate and is sealed at the upper part is fixedly sleeved on the first drainage cylinder, a lower opening is formed in the second drainage cylinder, a second drainage channel is formed between the inner wall of the second drainage cylinder and the outer wall of the second drainage cylinder, an annular stirring cavity is formed between the outer side surface of the second drainage cylinder and the inner wall of the mixing cavity, and the liquid outlet pipe is communicated with the upper part of the stirring cavity; the stirring device is characterized in that a plurality of stirring shafts are arranged in the stirring cavity, a plurality of stirring blades are arranged on the stirring shafts, and a planetary gear mechanism for driving the stirring shafts to rotate around the self axis and revolve around the tower body axis is arranged in the transmission cavity.
By adopting the technical scheme, sewage flows into the lower part of the mixing cavity from the liquid inlet pipe and is primarily mixed with ozone diffused by the aeration disc to form a gas-liquid mixture, the gas-liquid mixture flows upwards through the first drainage channel, then flows downwards through the second drainage channel through the upper opening of the first drainage cylinder and enters the bottom of the stirring cavity through the lower opening of the second drainage cylinder, meanwhile, the moving path of the gas-liquid mixture in the stirring cavity is from bottom to top, sequentially passes through a plurality of stirring blades, finally passes through the liquid outlet pipe, passes through the tail gas treatment device, removes a small amount of ozone, and is discharged through the water outlet pipe; in the process, the flow direction of the gas-liquid mixture is directionally guided, and the mixing path and time of the gas-liquid mixture are prolonged, so that the mixing uniformity of the gas-liquid mixture is improved, and the gas-liquid mixture can be subjected to sufficient reaction; the (mixing) shaft of stirring intracavity is done the rotation and is wound the revolution of tower body axis by planetary gear mechanism's drive simultaneously, thereby form annular stirring region, this stirring region is corresponding with annular stirring chamber just, thereby can carry out intensive mixing to the gas-liquid mixture of stirring intracavity, and two kinds of rotation effects of (mixing) shaft superpose mutually, cooperate annular stirring chamber, and the direction of flowing through of gas-liquid mixture self, the mixing homogeneity of gas-liquid mixture has further been improved, make its abundant reaction, thereby improve the reaction utilization ratio of ozone, efficiency and effect of sewage treatment are improved.
The present invention in a preferred example may be further configured to: the baffle plate comprises an annular outer ring fixed on the inner wall of the tower body and a fixed disc fixed at the top end of the second drainage cylinder, an annular rotating ring is arranged between the outer diameter of the fixed disc and the inner diameter of the outer ring, and the rotating ring and the fixed disc are rotatably arranged; the planetary gear mechanism comprises an inner gear ring fixed on the inner wall of the transmission cavity, a plurality of planetary gears, a motor fixed on the tower cover and a sun gear fixed on an output shaft of the motor, wherein the planetary gears are simultaneously meshed with the inner gear ring and the sun gear, and the planetary gears are fixedly connected with one end of the stirring shaft penetrating through the rotating ring.
By adopting the technical scheme, the stirring shaft can rotate around the axis of the stirring shaft and revolve around the axis of the tower body, so that an annular stirring area matched with the stirring cavity is formed; the partition plate can prevent sewage below the partition plate from splashing into the transmission cavity, so that the rusting and the aging of the planetary gear mechanism in the transmission cavity are reduced; meanwhile, the stirring shaft is rotated to penetrate through the rotating ring and drives the rotating ring to revolve, so that the stirring shaft can be prevented from interfering with the partition plate in the revolution process, splashing of sewage can be prevented in the rotating process of the rotating ring, and the service life of the planetary gear mechanism is prolonged.
The present invention in a preferred example may be further configured to: the lower part protrusion of the outer wall of first drainage tube is fixed with a plurality of horizontal poles, each the horizontal pole is evenly arranged along tower body circumference, the notch has been seted up to the lower open end of second drainage tube, the notch downwards inlay card in on the horizontal pole.
By adopting the technical scheme, the cross rod plays a role in supporting the second drainage cylinder and the fixed disc, and the second drainage cylinder and the first drainage cylinder are sleeved with the rotation stopping fixing structure, so that the situation that the fixed disc is driven to rotate by friction force in the rotating process of the rotating ring is avoided; simultaneously because the inlay card mode of horizontal pole and notch, the second drainage tube cover of being convenient for is established and is installed outside first drainage tube, improves the convenience.
The present invention in a preferred example may be further configured to: the rotating ring is provided with a rotating hole for the stirring shaft to pass through, the stirring shaft is rotatably connected with the rotating hole through a bearing, the stirring shaft sleeve is fixedly provided with an anti-seepage sleeve positioned below the rotating hole, the inner wall of the anti-seepage sleeve is bonded with a plurality of rubber rings fixed on the stirring shaft, and the upper part of the outer peripheral wall of the anti-seepage sleeve outwards extends to form an annular extension part for preventing sewage from splashing into the rotating hole.
By adopting the technical scheme, the bearing can improve the smoothness of the rotation of the stirring shaft, reduce the energy consumption, and meanwhile, the anti-seepage sleeve and the extension part are arranged, so that the splashing of sewage below the bearing can be reduced, and the aging of the bearing is reduced.
The present invention in a preferred example may be further configured to: the stirring shaft is sleeved with a plurality of catalytic plates, a fixing ring is jointly fixed between the catalytic plates on the stirring shafts and positioned in the same horizontal plane, the fixing ring is sleeved on the outer wall of the second drainage cylinder, and the fixing ring is rotatably connected with the second drainage cylinder around the axis of the tower body; be equipped with the chamber that holds that is used for placing catalyst granule in the catalysis board, the catalysis board is seted up a plurality of intercommunications and is held the through-hole in chamber and stirring chamber, and the aperture of through-hole is less than the diameter of catalyst granule.
Adopt above-mentioned technical scheme, the reaction of ozone can be accelerated to the catalyst granule in the catalysis board to through setting up solid fixed ring, when the (mixing) shaft revolution, drive the catalysis board on it and rotate around the tower body axis, make the rotation path of catalysis board suit with annular stirring chamber, thereby make the gas-liquid mixture homoenergetic in the stirring chamber contact the catalyst granule, thereby further improve gas-liquid mixture's reaction, improve sewage treatment's effect and efficiency.
The present invention in a preferred example may be further configured to: the annular that supplies fixed ring cover inlays is seted up to the periphery wall of second drainage section of thick bamboo, gu fixed ring is half-to-half separation structure, just gu two separation parts of fixed ring pass through fastener fixed connection.
Adopt above-mentioned technical scheme, through solid fixed ring cup jointing with the annular, can realize solid fixed ring's rotation and be connected to through half-separating structure, can be convenient for install solid fixed ring on second drainage tube.
The present invention in a preferred example may be further configured to: the catalytic converter is characterized in that an annular toothed belt with an upward tooth groove is fixed on the upper end face of the catalytic plate in a protruding mode, a supporting rod penetrating through a stirring blade is horizontally fixed on the stirring shaft, the stirring blade is rotatably connected with the supporting rod, and a driven gear meshed with the toothed belt is fixed on the stirring blade.
Adopt above-mentioned technical scheme, during the (mixing) shaft rotation, drive branch and rotate around the (mixing) shaft axis to through the meshing of driven gear and cingulum, rotate around the branch axis with the realization stirring vane, thereby on original (mixing) shaft rotation and revolution's basis, increased stirring vane's rotation, triple stirring motion mode superposes mutually, has further improved gas-liquid mixture's the mixture degree of consistency.
The present invention in a preferred example may be further configured to: the stirring blade comprises a straight blade and a propeller, the support rod sequentially penetrates through the middle part of the straight blade and the middle part of the propeller, and the driven gear is fixed on one side, close to the straight blade, of the propeller; the end face of the driven gear is provided with a slot, the straight blade is fixed with an insertion block which is horizontally inserted into the slot, and the tail end of the supporting rod is provided with a slip-off preventing piece for preventing the propeller from slipping off; and the driven gear is provided with a drainage hole in a penetrating way.
By adopting the technical scheme, the stirring blade is split into the straight blade and the propeller, so that the stirring blade can be conveniently installed, and the rotation stopping function is realized by the insertion of the insertion block and the insertion slot, so that the straight blade and the propeller can rotate together; when the propeller rotates around the axis of the support rod, the propeller rotates to guide the gas-liquid mixture outside the catalytic plate to the inner side, so that the gas-liquid mixture forms small backflow, and the gas-liquid mixture around collects and contacts with catalyst particles on the catalytic plate to fully react, thereby further improving the efficiency and effect of sewage treatment.
The present invention in a preferred example may be further configured to: the lateral wall of (mixing) shaft fixes the bracing piece that a plurality of levels set up, each the bracing piece is evenly arranged along the circumference of (mixing) shaft, just the lateral wall of bracing piece contradict in the lower terminal surface of catalysis board.
By adopting the technical scheme, the supporting rod plays a role in supporting the catalytic board, and the meshing stability of the driven gear and the toothed belt can be ensured.
The present invention in a preferred example may be further configured to: the tail gas treatment device comprises a treatment tank, the liquid outlet pipe is communicated with the upper part of the treatment tank, the water outlet pipe is communicated with the lower part of the treatment tank, and the upper part of the treatment tank is communicated with an air outlet pipe and an ozone destructor.
Adopt above-mentioned technical scheme, gas-liquid mixture flows to the treatment tank from going out the liquid pipe to fall down from the upper portion of treatment tank, the whereabouts in-process, ozone is because self density, automatic come-up and sewage separation, ozone come-up to the outlet duct, and carry out the processing of ozone through ozone destructor, the sewage of whereabouts then discharges through the outlet pipe, thereby finishes whole sewage treatment process.
In summary, the invention includes at least one of the following beneficial technical effects:
1. the first drainage cylinder and the second drainage cylinder are arranged to directionally guide the flow direction of the gas-liquid mixture and prolong the mixing path and time of the gas-liquid mixture, so that the mixing uniformity of the gas-liquid mixture is improved, and the gas-liquid mixture can be subjected to sufficient reaction; meanwhile, the stirring shaft in the stirring cavity forms an annular stirring area which is matched with the stirring cavity, so that the mixing uniformity of the gas-liquid mixture is further improved, the gas-liquid mixture is fully reacted, the reaction utilization rate of ozone is improved, and the efficiency and the effect of sewage treatment are improved;
2. by arranging the fixing ring, when the stirring shaft revolves, the catalytic plate on the stirring shaft is driven to rotate around the axis of the tower body, so that the rotating path of the catalytic plate is adapted to the annular stirring cavity, and the gas-liquid mixture in the stirring cavity can contact with catalyst particles, so that the reaction of the gas-liquid mixture is further improved, and the effect and efficiency of sewage treatment are improved;
3. through the meshing of the driven gear and the toothed belt, when the stirring shaft rotates, the support rod is driven to rotate around the axis of the stirring shaft, and the stirring blades rotate around the axis of the support rod, so that the rotation of the stirring blades is increased on the basis of the rotation and revolution of the original stirring shaft, and the triple stirring motion modes are overlapped, so that the mixing uniformity of a gas-liquid mixture is further improved;
4. through with stirring vane split into straight blade and screw, straight blade and screw can rotate jointly, when the screw rotated around the branch axis, the screw rotated the gas-liquid mixture guide to the inboard in the catalysis board outside, had the effect of guide gas-liquid mixture, made gas-liquid mixture form little backward flow, made gas-liquid mixture collect all around and contact with the catalyst granule on the catalysis board, made its abundant reaction to sewage treatment's efficiency and effect have been improved further.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1 and 2, the catalytic ozonation tower reactor disclosed by the present invention comprises a tower body 10, a tower cover 20 and an ozone generator 40, wherein a liquid inlet pipe 11 and an aeration disc 50 communicated with the ozone generator 40 are arranged at the lower part of an inner cavity of the tower body 10, a liquid outlet pipe 12 is arranged at the upper part of the tower body 10, and the liquid outlet pipe 12 is communicated with a water outlet pipe 13 through a tail gas treatment device 30; sewage enters the lower part of the inner cavity of the tower body 10 from the liquid inlet pipe 11, ozone generated by the ozone generator 40 is diffused to the lower part of the inner cavity of the tower body 10 through the aeration disc 50 and is primarily mixed with the sewage to form a gas-liquid mixture, the gas-liquid mixture is fully reacted in the inner cavity of the tower body 10 and then flows to the tail gas treatment device 30 through the liquid outlet pipe 12 to treat residual ozone, and finally treated water is discharged through the water outlet pipe 13 to finish the sewage treatment process.
As shown in fig. 2 and 3, a partition plate 2 is arranged in the tower body 10, the partition plate 2 divides the inner cavity of the tower body 10 into a transmission cavity 22 and a mixing cavity 21 from top to bottom, the lower part of the inner wall of the mixing cavity 21 extends inwards to form an annular blocking annular plate 31, the liquid inlet pipe 11 and the aeration disc 50 are both positioned below the blocking annular plate 31, the inner side of the blocking annular plate 31 extends upwards to form a first drainage tube 32 with an upper opening, and the inner cavity of the first drainage tube 32 forms a first drainage channel 34; a second drainage cylinder 33 which is positioned above the blocking annular plate 31 and is sealed at the upper part is fixedly sleeved on the first drainage cylinder 32, a lower opening is formed in the second drainage cylinder 33, a second drainage channel 35 is formed between the inner wall of the second drainage cylinder 33 and the outer wall of the second drainage cylinder 33, an annular stirring cavity 36 is formed between the outer side surface of the second drainage cylinder 33 and the inner wall of the mixing cavity 21, and the liquid outlet pipe 12 is communicated with the upper part of the stirring cavity 36; the gas-liquid mixture flows upwards through the first flow guiding channel 34, then flows downwards through the second flow guiding channel 35 through the upper opening of the first flow guiding cylinder 32, and enters the bottom of the stirring cavity 36 through the lower opening of the second flow guiding cylinder 33, and the gas-liquid mixture moves from bottom to top in the stirring cavity 36 and flows out of the tower body 10 through the liquid outlet pipe 12.
As shown in fig. 3, a plurality of cross bars 321 are fixed to the lower part of the outer wall of the first drainage cylinder 32 in a protruding manner, each cross bar 321 is uniformly arranged along the circumferential direction of the tower body 10, a notch 331 is formed at the lower opening end of the second drainage cylinder 33, and the notch 331 is downwardly inserted into the cross bar 321.
As shown in fig. 2 and 3, a plurality of stirring shafts 41 are arranged in the stirring cavity 36, a plurality of stirring blades 42 are arranged on the stirring shafts 41, and a planetary gear 52 mechanism 5 which drives the stirring shafts 41 to rotate around the self axis and revolve around the axis of the tower body 10 is arranged in the transmission cavity 22; when the gas-liquid mixture flows through the stirring cavity 36 from bottom to top, the gas-liquid mixture sequentially passes through the plurality of stirring blades 42, in the process, the stirring shaft 41 in the stirring cavity 36 is driven by the planetary gear 52 mechanism 5 to rotate and revolve around the axis of the tower body 10, so that an annular stirring area is formed, and the stirring area is just corresponding to the annular stirring cavity 36, so that the gas-liquid mixture in the stirring cavity 36 can be fully stirred and mixed;
as shown in fig. 3 and 4, the stirring shaft 41 is sleeved with a plurality of catalytic plates 6, accommodating cavities 61 for accommodating catalyst particles 62 are arranged in the catalytic plates 6, the catalytic plates 6 are provided with a plurality of through holes 63 communicating the accommodating cavities 61 with the stirring cavity 36, and the aperture of the through holes 63 is smaller than the diameter of the catalyst particles 62, so that the ozone reaction rate can be improved; fixing rings 64 are jointly fixed between the catalytic plates 6 on the stirring shafts 41 and located in the same horizontal plane, a ring groove 332 is formed in the outer peripheral wall of the second drainage cylinder 33, the fixing rings 64 are of a half-to-half separation structure, two separation parts of the fixing rings 64 are fixedly connected through fasteners 65, the fasteners 65 are bolts and nuts, the fixing rings 64 are embedded on the ring groove 332 in a sleeved mode to achieve axial line rotating connection with the second drainage cylinder 33, when the stirring shafts 41 revolve, the catalytic plates 6 on the fixing rings are driven to rotate around the axis of the tower body 10, the rotating path of the catalytic plates 6 is made to be matched with the annular stirring cavity 36, and therefore gas-liquid mixtures in the stirring cavity 36 can all contact with the catalyst particles 62; and the bracing piece 66 that a plurality of levels set up is fixed to the lateral wall of (mixing) shaft 41, and each bracing piece 66 evenly arranges along the circumference of (mixing) shaft 41, and the lateral wall of bracing piece 66 contradicts in the lower terminal surface of catalysis board 6, and bracing piece 66 plays the effect of supporting stable catalysis board 6.
As shown in fig. 5, a support rod 43 passing through the stirring blade 42 is horizontally fixed on the stirring shaft 41, and the support rod 43 is rotatably connected with the stirring blade 42 around the axis of the support rod 43; the stirring blade 42 comprises a straight blade 421 and a propeller 422, a driven gear 423 is fixed on the propeller 422, a drainage hole 424 is formed in the driven gear 423 in a penetrating manner, and the support rod 43 sequentially penetrates through the straight blade 421, the driven gear 423 and the middle part of the propeller 422; the end face of the driven gear 423 is provided with a slot 426, the straight blade 421 is fixed with an insert block 425 horizontally inserted into the slot 426, the tail end of the supporting rod 43 is connected with a screw cap in a threaded manner, and the screw cap is a disengagement preventing piece 427 for preventing the propeller 422 from disengaging; the straight blades 421 and the propellers 422 are sleeved on the supporting rods 43 in sequence, and then the nuts are screwed, so that the stirring blades 42 can be installed, and the straight blades 421 and the propellers 422 can rotate simultaneously through the insertion of the insertion blocks 425 and the insertion grooves 426; meanwhile, an annular toothed belt 67 is fixed on the upper end face of the catalytic plate 6 in a protruding mode, tooth grooves of the toothed belt 67 face upwards, the toothed belt 67 is meshed with the driven gear 423, and the toothed belt 67 and the driven gear 423 are preferably made of plastic materials, and are more preferably POM plastic;
when the stirring shaft 41 rotates, the supporting rod 43 is driven to rotate around the axis of the stirring shaft 41 and the stirring blade 42 rotates around the axis of the supporting rod 43 through the meshing of the driven gear 423 and the toothed belt 67, and when the propeller 422 rotates around the axis of the supporting rod 43, the propeller 422 rotates to guide the gas-liquid mixture outside the catalytic plate 6 to the inside, and the effect of guiding the gas-liquid mixture to form small backflow is achieved.
As shown in fig. 2 and 3, the partition plate 2 includes an annular outer ring 23 fixed on the inner wall of the tower body 10 and a fixed disc 24 fixed at the top end of the second flow guiding cylinder 33, an annular rotating ring 25 is arranged between the outer diameter of the fixed disc 24 and the inner diameter of the outer ring 23, the fixed disc 24 and the outer ring 23 jointly support the rotating ring 25, the rotating ring 25 is rotatably connected with the fixed disc 24, the rotating ring 25 is provided with a rotating hole 251 for the stirring shaft 41 to pass through, and the stirring shaft 41 is rotatably connected with the rotating hole 251 through a bearing;
the planetary gear 52 mechanism 5 comprises an inner gear ring 51 fixed on the inner wall of the transmission cavity 22, a plurality of planetary gears 52, a motor 54 fixed on the tower cover 20 and a sun gear 53 fixed on the output shaft of the motor 54, wherein the planetary gears 52 are simultaneously meshed with the inner gear ring 51 and the sun gear 53, and the planetary gears 52 and one end of the stirring shaft 41 penetrating through the rotating ring 25 are fixedly connected; the rotating stirring shaft 41 penetrates through the rotating ring 25 to drive the rotating ring 25 to revolve, so that the stirring shaft 41 can be prevented from interfering with the partition plate 2 in the revolution process, the splashing of sewage below can be prevented in the rotating process of the rotating ring 25, and the service life of the planetary gear 52 mechanism 5 is prolonged.
In order to further improve the effect of preventing sewage from splashing below, as shown in fig. 6, the stirring shaft 41 is fixedly sleeved with the anti-seepage sleeve 7 positioned below the rotating hole 251, the inner wall of the anti-seepage sleeve 7 is bonded with a plurality of rubber rings 71 fixedly sleeved on the stirring shaft 41, and the upper part of the outer peripheral wall of the anti-seepage sleeve 7 extends outwards to form an annular extending part 72 for preventing sewage from splashing into the rotating hole 251.
As shown in fig. 1, the tail gas treatment device 30 includes a treatment tank 16, a liquid outlet pipe 12 is communicated with the upper portion of the treatment tank 16, a water outlet pipe 13 is communicated with the lower portion of the treatment tank 16, and an air outlet pipe 14 and an ozone destructor 15 are communicated with the upper portion of the treatment tank 16.
The implementation principle of the embodiment is as follows: sewage flows into the lower part of the mixing cavity 21 from the liquid inlet pipe 11 and is primarily mixed with ozone diffused by the aeration disc 50 to form a gas-liquid mixture, the gas-liquid mixture flows upwards through the first drainage channel 34, then flows downwards through the second drainage channel 35 through the upper opening of the first drainage cylinder 32 and enters the bottom of the stirring cavity 36 through the lower opening of the second drainage cylinder 33, and meanwhile, the gas-liquid mixture moves in the stirring cavity 36 from bottom to top, sequentially passes through the plurality of stirring blades 42 and is discharged from the liquid outlet pipe 12; in the process, the flow direction of the gas-liquid mixture is directionally guided and the mixing path and time of the gas-liquid mixture are prolonged through the first drainage cylinder 32 and the second drainage cylinder 33, so that the mixing uniformity of the gas-liquid mixture is improved, and the gas-liquid mixture can be subjected to sufficient reaction;
meanwhile, the stirring shaft 41 in the stirring cavity 36 is driven by the planetary gear 52 mechanism 5 to rotate and revolve around the axis of the tower body 10, so that an annular stirring area is formed, the stirring area is just corresponding to the annular stirring cavity 36, the gas-liquid mixture in the stirring cavity 36 can be fully stirred and mixed, the stirring shaft 41 rotates and rotates through the meshing of the driven gear 423 and the toothed belt 67, the stirring blades 42 are driven to rotate around the axis of the supporting rod 43, and the triple stirring motion modes are overlapped, so that the mixing uniformity of the gas-liquid mixture is further improved; when the propeller 422 rotates around the axis of the support rod 43, the propeller 422 rotates to guide the gas-liquid mixture outside the catalytic plate 6 to the inside, so that the effect of guiding the gas-liquid mixture is achieved, the gas-liquid mixture forms small backflow, the gas-liquid mixture around is converged and is in contact with the catalyst particles 62 on the catalytic plate 6, and the gas-liquid mixture is fully reacted, so that the efficiency and the effect of sewage treatment are further improved;
after the gas-liquid mixture is stirred and mixed by the stirring cavity 36, the mixture is fully reacted and mixed, and then is discharged by the liquid outlet pipe 12 and falls down from the upper part of the treatment tank 16, in the falling process, ozone automatically floats up due to the density of the ozone and is separated from sewage, the ozone floats up to the gas outlet pipe 14 and is treated by the ozone destructor 15, and the falling sewage is discharged through the water outlet pipe 13, so that the whole sewage treatment process is finished.
The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.