CA2003990A1 - Pneumatic conveyor for grainy material and suction nozzle for use in such conveyor - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A hopper subjected to a suction effect of a vacuum source such as a vacuum pump is connected by a hose to a suction nozzle thrown into a container for grainy material and an ejector is provided to supply the suction nozzle with pressurized air, and thereby a smooth pneumatic conveyance of the grainy material is achieved.
A cap laterally provided with openings is slida-bly put on an open end of the suction nozzle and a total opening area of the lateral openings is adjusted by axially sliding the cap on the open end of the suction nozzle.

Description

20~-~g9~

PNEUMATIC CONVEYOR ~OR GKAINY MATERIAL
AND SUCTION NO~ZLE ~OR U~E :LN SUCH CONVEYOR

~ACKG~OUND OF THE INVENTION
The present i.nven~iorl relates to a pneurilatic conveyor adapted for pneumati.c shock-free conveyance of grainy ~aterials such as tablets or capsulated pills and flJrther to a suction no~.zle used ;n such a conveyor.
The prior art pneumatic conveyors for grainy materials are gen~rali.y c~assi.fie(1 into two types, one relying upon the suction ef~ect of a vacuum pump for conveyance of the grainy materials and the other rely-in~ upon pressuri.7,ed air introduced into a sealed c,ontainer whi.ch contains a ~atch of the grainy materi-al.s so that l;hese grainy materials may be conveyed 1~ rlom 1;he container batch by batch.
The former method of prior art which relies upon the suction effect of t,he vacuum pump for conveyance of 1;he tablets is disclosed by Japanese Disclosure Ga~ette No. ~981.-113615, according to which a tablet suction 2~ duct, (hose) is connected to a sealed container and the : latter is deco~pressed by a vacuum pump. .However, too many~tablets are sucked a~: once through the front end of the sucti.on duct and lm~ediately blocking occurs with.Ln t~e suction duct.
2~ I]pon occurrence of such a blockage, the negative pres-ZOg~39~0 suce at th~ vaeuum side rapidly increases and the b.lo<:kage ~lears, with the result that the tablets are sucked all at once through the suction duct. 'rhus, the s~lc,t;on is ullstab]e and the tablets intensely collide wit,h one ~nother.
Cerl,<lin].y, the negative pressure at the vacuum ~;de and, therefore, the velocity of the air flow ~ay be increase~.t t;o avoid said blockiTlg. However, this wou.ld incorlvenierll,ly increase the inertial force of the 1~) (.abLet;s arld also the shock generated when the tablets oo~.lide wi1,h one another and with the equipment walls.
In ;lny case, the conventional method utilizing l,he suction effect of the vacuum pu~p is apt to damage l,lle l,ablets and to yield a certain percentage of unac-1~- cc~t;ahle product~
~ rhe latt;er prior art method comprising the steps of sealing the cont,ainer filled with the tablets or the like alld sul~plying pressurized ai~ into the sealed corlt,airler so as to convey the tablets or the like from t.he cont;ainer batch by batc:h is disclosed by Japanese D:i~c,]osllre Ga~et-te No. 1987-2641221 according to which t.he t,ablet;s are fed from a hopper illtO an air-tight storage cont.ainer through a valve l~ounted in a t,op wall there-of, ~aid valve being openecl at this moment, and then 2~ said st,orage c:on-5,ajner is supplied from an air s~pply l~i}~e wit.h pressuri~ed air wi.th said valve being -`-' Z()83~gO

cLosed,to convey the tablets from -the container through another conveyor ~ipe. With such a meth~d re1ying on l>res~uri zcd ai r, the next supply of tablets from the hopper must be stopped~and the air~tight sl;orage con-tainer already filled with the tablets mus~ be sealed, for every conveyance. ~hus, the conveyance occurs batch by batch and any continuous operat-ion is impossible.
Furthermore, t;here must; be provided a valve serving to seal the corltairler f-illed with the tablets or the like for every bat;c}l and, in conse-quence, peripheral devices for the conveyor must be com-p]icated, correspondingly increasing -l:ot:al cost.
MoreGver, this prior art conveyor uses stainless piping (i.e., ~iping ofa sanitary type) which 1~ necessarily restric~s the degree Or freedom and corre-~pondingly makes mair~terlarlce such as cleaning rather difficult.

Sl)MMARY OF Tl-lE INVRNTION
The present invention provides a pneumatic conveyor for grainy material, utilizing the grainy material conveying method under the suction effect of a vacuum pump so comb;ned with -the grainy material conveying method under the effect of pressuriæed air,that the grainy materi~l to be conveyed 2~ is free from blocking during operation of the conveyor 2~1~3990 in spi te of its relatively simple structure.
]'his is achieved, in accordance with the preserl1 inv-~ntion, by a pneumatic conveyor for grainy matelial, comprising a vacuum ~ource such as a vacuum pump, a hopper sut)jected l;o the suction effect of said VaCIIUm SOIIrCe ~ el s~lction nozzle connected by a hose to said hoE~per and adapted to be thrown into the grainy material, and an ejec-tor servillg to supply sa:id suction nozzle with a prexsurized air.
In such a pneumatic conveyor, the inner surface of the hopl)er is preferably formed by resilient material to rotect l he grainy material against damage. Useful mater;al includes Neoprene rubber, urethane foam, 1'eflon*and urethane rubber, all having sufficient shock absorbing ability.
Preferably, the hose is tangentially mounted on the side wall o~ the hopper so that the grainy mate~ial may spirally fall withill the hopper.
The ejector nozzle is preferably so curved that a jet of pressuri~.ed air may flow along the inner wa~l of the hose.
The present invention also provides a suction nozzle for us~ in a pneum~tic conveyor ~or grainy material and which serves to prevent the grainy material fro~ blocking tne intake during operation of the conveyor.
*Trade Mark Ll Z~3~9~

~ccording to the present invention, this ix achieved by a suction nozzle for use in a pneumat ic cc~nveyol for gr~i.ny material~ comprising a cap la~,eraJ.Iy I~rovided with openings and slidably moun~e(J
about the open end of the suction nozz].e so that said ~ap may be axially s].i.d on said open end to vary the t,otal opening area of said l.ateral openings thereby lo adjust the suction capacity for the grainy material.
I:n ~ucha xuction nozæle, the cap is preferabl.y of lt! ;~ (!ua:l sl,ruct.ure consisting of an outer cap and an inrlel cap which m~y be reLatively rotated to vary said t,ol,;ll operl.i.ng area. The suction nozzle is preferably plovj(~e~ in its front or intake end with air jet ports so that any lurnps of the grainy material may be collapsed under air jet stream pressure provided from these air jet ports. Preferably, I he ~uct.ion nozzLe is provided,at locations correspond-ing to the Fespective lateral openings of the c~p,with air (intake) suction perforations in order to maintain gaps or spaces among the individual grains being sucked up and transported.
~'he present i.nvention provides effects as set rOI't,~l ~)elow:
A. The vacuum su~tion effect is combined with pressur.ized ai r at a predetermined level supplied rrom t:he eject;or nozzle so as to avoid occurrence of t-lockirlg within 1.he hose;
~ . 'rhe c.lp l.atera].ly provided with open;.ngs is .

. .

:` z~ o slidably mounted around the open end of the suction nozzle so that said cap may ~)c ~xiall~ sl;ci on s~id open end to vary the to1,.1.1 open.ing are.1 of- sai(i lat,eral openings and there~y t;o adjllxtthe s~lction caE-acity ror t;he gr.l:iny mal,eri.al.. 1n l,h.;s marlner, even i~ -the suc-tion no7,~1.e has ~-een embe(lded in a mass of t,ab].ets, l,he l,ab]ets are cont;:i.nuolls]y s~cked and conveyed, without, blocking with;rl the open erld of the suct,ion no~.~..le.

10C. The tab'l.et,s ar-e progrexsivel~ decelerate(l as they ascend t,hrough the hose, t;hus corlveyed at a rela-t;i.vely l.ow ve~.ocil;y into 1;he hopper so as not. t,o d.lmage the -tablets coll.iding w:i.th one .~not,her so t.hat the pneumat;ic conveyor of the presen~, ;.nvention can convey l~britt].e or frag;le grainy nlateria~ S~lCh as cap~u-:I.ated or sugar-coated tablets.
D. After deenergization of the vacuum source, the tablet;s remainirlg wi1;hin t;he hose fa~l at a rela-~ivel.y slow ve~.o(i.ty because the pressuri.7,ed air c~on-l;inues to be suppli.ed and decelerates l;he ~elocity atwhich the tablets fall through the hose;
E. Combi.nati.on of t,he vacuum suc,tion ancl the ejector makes operati.on easier. The container for the gralny mat.eria] into which t;he sllct.ion no7.7.1e is placed req~ires no seaLing ~earls and cclrresponding:l.y , ex-l,remely coml>act equi.pment,resu1ts;

7o~

F. Even in t;he case ol conveyarlce from a large-sizeri hop~er, conveyanc~ can be smoothly performed tle<au~e o~ suc~ simp.liried e4uipmerlt; and ~ . I`he hoxe made of polyethylene or tne like wi.ll achieve a high degree of fr.eedom from mainte-nance such as clealling.

I~Rrl~F I~ESCRIPTION ~F THF. ~RAWI:NGS
~ he at)ove and o1heI ad~antages of the invention wi.l.l be seen in reference to the description taken ;.n 1~ collnecti.on w;th the accompanyi.ng drawings, in which:
~ ig. t ;s a perspective view showing a pneumatic conveyor for grainy material constructed in accordance Wittl the prexent i.nvent.ion;
Figs. 2A arld 2B illustrate a hopper of the invention in perspective and sectional views, respec-1.ive~y;
Figs. 3A and 3~ i.llustrate a first embodiment of the suction nozzle construc-ted according to the inven-t.:i.on in perspective and frontal. views, respectively, Figs. 3C and 3D being both sectional views correspond-ing to F;g. 3A;
F;gs. 4A, 4B and 4C illustrate a second embodi-ment of the suction nozzle constrllcted according to the inverltion in a pers~ective view, in A side vi.ew par-2(~ 390 tially in section, and in a frontal view, respectively;Fig. ~ is a side view i]lustratin~ a third emt)od;ment o1` the suction no~z.~e const;ructed according lo l:he inverllion,paI-tia:lly in secti.on;
Fig. 6A and 6B illustrate a fourth embodiment of t:he sllction no~.71e constructed according to the inven-tion,in a s;de view partially in section and irl a tronta] Yiew, respectively;
Figs. 7A, 7B and 7C, which appear on Shee'~ 8 of the lrl drawings with Fig. 5, a~e illustrative diagrams for EXPERIMENT B;
~igs. 8A, 8B and 8C are il.lustrative diagrams ~or RXP~RIMRNT B;
Figs. 9A and 9B are i.llustrative diagrams illus-trati.ng flow velocity distribution within the hose 50 .1~ ;n th ~:ase of conveyarlce by suction by the vacllum ~ump and pressurized air, respectively; and Figs. 10~, 10B, 10C and 10D are illustrative li.lgrams for ~:XPE~IMENT C.

DETAlLED DESCRIPTION OF THE INVENTION
While the invention will be described with respect to tablets as an example of the grainy materi-` al, it shou].d be understood that the invention is apl)l-ic~ble also to the other types of grainy materials such as capsu~;lted pills~small-sized confectionery and 2~)()3~39(~

other grains and 2articulat9 material.
F:i~. 1 i.1lustrates ar~ entire pneumat;c conveyor of l,he invention comprising a hoppe~ 10, a container 6~
containing therein tablets 70, a xuct;iorl no7.Y,le ~0 embedded in tablehs in said container 60, a gas supplying pipe 35 adapted to supply said sllctiorl no~,Y.le 20 wit,h pressur-ixed ai.r, and a hose 50 connecting sai.d hopper 10 wi,th said SUCi:iOrl noz~le 20. The hose 5() i5 preferably made of wired Tetoron*
Referring to Figs. 2A and 2~, a xuction pipe 11 is connected with the hopper 10 so that l;he interior of xa:id hoppel 10 i.s decompresse(i under operat-ion of a vacuum xource such as a vacuum pUMp ( not: shown? and thereby the -tablets 70 are sucked up t,hrough the hose 1~ 50.
Inner w~ll of ~;he hoppeI~ 10 :ix coated with suitable bufer material 12 to alleviate undesirable shock which would otherwise be generated when 1;he t;ablets xtrike againxt the inner ,wa.L]. as 1;hey are sucked up.
The hopper lO has a xhutt.er 13 pivotalLy mounted on a ~ower end thereof. Re~erence numeral 14 designates a sta~ic presxl~re gauge and reference numeral 15 desig-nates a va]ve used to shut the suction pipe 11.
2~ The hose 50 is t.angenti,ally mounted on the side wa] 1 o:f the ho~>E~er l.0, as shown by Fig. ~A~ so that t,he *Trade Mark ~0~;39~1 tablets 70 being sucked tlp through the hose 50 spirally descend al.orlg the innec wa.ll of t,he hopl)er under a decelera(,-ing erfect, and ale accumul.ated on the bottom of the hopper lO.
U~on deenergi~at:ion (i.n response to a timer or l,he like) of the vacullm ~ump after a predetermi.ned quarltity of tab:lets hax heerl accu~ulated in the hopper It), thc- shutter ]3 is pusht?(3 open by the weight of the -ta~let;s l,hemselves 70 and ~,hereby the tab~ets 70 are ]0 d;.scharged downwards.
F':ig. 3A, 3B, 3C and 3D show a first embodiment of the suction noY.,7:i.e 20 provide(l according to the present invention, which comprises a mai.n ~ody 30, an upper portion 31 connected by bo].ts 33 -to said main body 30 and an 1~ eje(,tor 34 provided in sai.d ~pper porl:ion 31.
The upper porti.on 31 re<eives the rear end of the main body 30 so as to define be-t~een the inrler wall of th~ upper portion 31 and the outer periphery of the n~air~ body 30.~said e,ject,or 3~ which comprises1 in turn~
an annular ejector passage 34a and an annular tapered ejector nozzle 34b so that a quantity of pressurized air supplied through -the gas supply pipe 35 is fed int,o said annular ejector passage 34a and then fed through said eject.or nozzle 34b into a ca~ity within 2~ I:he upper portion 31.
W;th t,he suctiorl nozzle of the present invention 1 () z~

wh.ich comprises the ejector of this type, not only t,he grains, i.n general,, are accelerated a].ong the e,jec,l,or t)ul; a~so are always supplied, as 1,hey flvw l,h:rollgtl the ejector, to the hose, wi.th an adequate ;1~ 4t~an~i.ty of a.i.r to maintain suit;able gaps or spaces between the i ndiv idual grains, and thereby to avoid blockage within the hose.
~ e main ~)ody 30 of the suction noz~,le has a tablet suction port 36 opening at a front or intake end thereof, 1() I,hrough which the tablets 70 are suclced. The main body 3Q ;~ fllrt;her prov.i.ded through the side wal.l 30a t,here-o~ wi ~i~ a plura]ity of ai.r suction perforations 37 used l,o m;lirlt,ain the above-mentioned gaps or spaces among l he i ndivi dual tablets 70 which have been sucked l~ ~,hrough 1;1-le tabl.et,s sucti.on por-t 36. More specifical].y, i r many ~;ablet,s are pr~sent at~ the tablet suction port 36 w.hile suction is ~pplied to these tablets, the quantity of air wi.ll be in short supply. To remedy such shortage, a x~pplemerltary quantity of air may be sucked through the ~0 air xucti~r~ perforations 37 to maintain the gaps or sl~aces between the tablets being sucked.
The upper portion 31 of the suction nozzle is connected to the hose 50. 0-rings 38, 38 are used for lcak prevention as wel.l. as fixation of the hose 50.
2~ The suction nozzl.e 20 constructed as has been ment,-ione(i above is provi.ded at i.ts front end w;.th a cap ~ 20~99~

~0 ~ounted thereon in axially s~idable manner.
The cap 40 ;.s formed with o-per~ings ~1 of which l~he t:ota:1 area varies as ~he cap ~0 is axially slid F:aeh of Ihese openings 41 :is t-shaped as viewed in il;s ax-ial ~ect-ion1 consisti.ng of a s;.~e ~ortio~ ~la and a t)o~1o~n ~or1;ion 41b both ~)eing ~ubslar~tilll.y rect;angu-l.ar.
Speciiically, when the C-lp 40 hax been s~.id to the rea~most positjon on the xuction no~YIe 2() as seen 0 itl ~ig.~, said side portiol~s 41a ol t;he respective openi.ngs 41 are enti.rel.y covered ~y the side wall 30a Or t.he suetion no7.~le's main t~oliy 3(), resu.ltirl~ .in t;he minimum opening ~rea provided only ~y the bottom por-tions 41~.
1~ Oppositely, the xide port;ions 41a of` the respective open:ings 41 are progressively opened and the total opening area is enlarged, as the cap 40 is slid forward (in the direction indicated by arrows~ a~ seen in F;.g. 3~.
In this manner, the suction capaclty of the suc-tion noz~l.e 20 can be adjusted by axial~.y slid:ing the cap 40, e.g., for re~atively larger tclblets 7~, the cap 20 i.s slid forward to enl.arge the openin~s area while for- re].atively smal.l tablets 70, the ca~ 20 is slid 2:~ rearwardly, and thereby the tablets 70 are prevented from blocking the intake to the suction noæzle.

~oal3990 Fi.g. 4A, ~13 and 4C show a second embodiment of ~:he x~lction nozz,le ~0 constructed in accordance with the preserll, irlvent,ion, in which 1;he c-ap 4() i,s of a dual, st,ruct,ure consixti.rlg of an outel cap ~2 and an inrler 5 eap 4~.
The o~lter cap 42 and ;nner cap 43 ~re respec-tivel.y provide~ w-ith openings 44, 45 of the same size 80 ~:h.lt t,he openjng area oE the tabl.et suction port 36 may be reduced by relatively rotating t,he outer cap 42 and t,he inner eap 43 tsee ~ig.4C).
Such an arr-angement, allows the opening area of the tab.let, SIICt;iOIl port, 3~ to be 1'i.nely adjusted.
Fig. 5 shows a th;,rd embodiment of the s~ction nozzle 20 constructed acco.rding t,o the present inven-tion, in hhich the ejector nozzle 34b defi.ned between t.he inne.r sur~ace ol' the suct,iorl noz~le's upper portion 31 and the outer peripheral surface of the suction no7,zLe's ola; n l~ody 30 a~ound t,he rear end thereof is inwardl.y c~lrved so as t,o force the pressurized air supp~i.ed from t,he gas supplying p,ipe 35 in a streamline direction.
The pressuri.zed alr supplled through this curved : ejector nozzle 34b forms an air stream flowing subst~n-t,ia.l.l.y al.ong the inner surface of the hose 50, as indicat,ed hy an arrow x, and t,his assists formation of a l.amina7 fl.ow within the hose 50.

~3~99~1 Tnus, the possibility of grainy mal;eria~. bJockin~
t,he hose is effectively reduced.
Fig. 6A and fi~ show a fourth embodiment ol' I,he xucl,ion no7JY~le 20 constructed according t;o the present, o ;nvention, in wh.i.ch t,he ma.i.rl body 30 of t;he suctior noz~,]e ~0 is provided at its frorl1; end with ai.r ,jet por~,~ 46 so that; the pressllrized air supplied from the gas xupplying pi.pe 35 i.nto the annular ejector passage 3~a may he t~len partially introduced i.nt,o these air jet, por~;s ~t6.
Sugar.-c,oated tablets or the like someti.mes sti.ck t,o one another to form lumps, but these lumps are broken apart to yield individual tablets 70 under the ac~ion of the air jet provided from said air jet ports 46 and ther~by lo suct,:iorl of tlle tablets 70 can be smoothly carried out.
Tn t,he pneumatic conveyor constructed in accord-ance with the present invention as has. been mentioned above, the tablets 70 are çontinuollsly sucked through l:~le SUC, ti on rloz~le 20 resting in the container 60 for said tablets 70 by evacuating the hopper 10 under the e~rfec t Or t;he vacuum source such as the Yacuurn pump (not showrl). During this suction, the cap 4() may be a~i.ally ~lid on the suction nozzle 20 to change the opening area and t,hereby to adjust the suction capacity ',~o to a desired l.evel.. The tablets are maintained apart r rom one arlo1h~r, since the tablets being transported are ~0()3~9~

accelerated along the ejector section of' the suction nozz].e 20 with plenty of air.
The tablets 70 are pr-ogressivel~ dece]erated as l,hey ascend l,hrollgh the hose 50, t;h1l~; cor1veye(l at a ;, relati.vely l.ow vel.ocity into the hop~er ]~, ~hen spi-ral1,y descen(l a.l.ong the inner wa.l.l of tt1e hop~er 10 and accumulate on t,he bottonl of the hopper l(). The pro-gressive deceLeIat;,on of the /;ablet,s 70 c~ccllr.rir1g ~s t,hey ascend through -the hose ~0 is believed to ~)e due I0 t,o a ~act t,hat, the hose 50 an(i the hopper 10 are sup-plied witll a part, of the pressuri.ze~ .li.r su~lied f'rom the e.jector and the-reh~ the static ~ ossure w.ithin t;he~
hose ~0 is lowered.
Upon deenergization of the vacul1m~source such as l~ l,he vacuum pump after a pred~t.erm.ir1ed quan1,ity oJ' 1;nblet,x have been accll1nul.lted i.n the hopper lO, the shutter 13 is pushed open by the weight of the tablets 70 themselves and therehy the -tablet~ 70 are discharged downward .
Thus, no blocking of the tablets 70 occurs within the hose ~0.
: ~ With the conven-tional tablet conveying method tillzing the suctior1 effect of the vacuun1 pump, when the hopper is evacuated by the vacuun1 pump, p.lenty of :2~ tablets are sucked up into the suct,ior1 nozz]e at once, re~u]tinLS in b].ock~ge. This, .i,n turn, shaI~)1.y enhances 2~ 990 the vacuum level within the ho~>per and the b.locking collapses urlder -the resultirlg negative pressure.
Col,~apse Or SUCt1 ~)J.ockin~ causes the tablel,s which have formed t,he b:lo~ka~e to be sucked up 5 through the hose instantaneously and the suction nozzle sucks a new mass of the 1,ablet,s, resu]ting in b'lock again. Thi.s is repeated.
Therefore, it, has usua.l1y been i.mpossible ~OT-the pneumatic conveyor of' the prior art ~be used to conveylO grainy materia.l which is ~)ri.tt,.l.e or fragile such as capsulated or- sugar-coate(i tablets.
The present .inverltion so.Lves such l:echni,cal.
probl.ems encount,ered by the pneumatic conveyor of the well known prior art b~ providing the suction nozzle with a unique ejector.
Var;.ous experiments conducted for developmerlt o~
this invention will be described below.

F.XPERIM~NT A

Efficiency of tabl.et conveyance was examined in relation to the position at which the ejec1,or 34 is selectively mounted (See Fig. 7A, 7B and 7C).
1. Fig. 7A shows the case in which a pair of the ejector~s 34 were mounted on the suction nozzle 20 and on Lhe hose 50 at an intermedi.ate position therealong, respecti.vel.y. First, pressurized air of 4kg/cm~ and I ~i 3~

I,hen pressurized air of 6kg/cm2 were supplied from l,hese e,jectors 3~ without evacuation of the hopper- b~
I,he vacuum pump.
This experimerll, indicated l;hat no convey.lnc~-? of' the t~lets W-lS achieved in .~ny case. Accordingly it was round that the pre~uriY.ed air higher 1,harl .~R() fikg/cm2 must he supplied in order to achieve desir-ed eorlveyance only under the effect of press;lrized air.
~ . Fig. 7~ shows the case in which a sin~le i;; eje~ctor :~ W.15 mount,ed on the hose 50 at, ~n int,ermedi-..te posi~,ion l,hcre.llong and the hopper 10 was evacllat;ed ~,y the vacuum pump.
Tl, w<~ f`ound from this experiment that the ~rexsurized a;r supplied from the ejector was apt to low ~ackwa~(l and, in consequence, the tablets wcre no1;
conveyed.
3. Fig. 7C shows the case in which a single e,joctor 39 was mounted on the suction nozzle and the hopper 10 was evacuated by the vacuum pump. More spe-''O c;fic,ally, the degree of vacuum within the hopper 10W.15 enh.lrlced 1,o a leve~ at which the conveyance of the t.ablet~ can be achieved only under the suction effect arl(l then the pressurizetd air of Ikg/cm2 was supplied from t,he ejector 34.
2~ Tt was found from this experimerlt that the t,at~let~ carl t)e buoyant,ly conveyed through the ho~e.

, 2~ 90 EXPERIM~NT B
Air fl.ow vel.oci.t,y within the hose 50 was meas-uted under var:io~ls con(iiti.orlx as i'ol~owS ~See F:ig.
8A, 8P, and K~,). rt SllOU.Id hc urlderxt,oo(i t,hat such meas ;) uremer1t was corl(i~ ted at a posi~:i.on closely adjacent l:he suc1:ion noY,z:l.e 20, al, a poxi.tion a.l,ong the hose 50 slight:1.y above said posi1,ior1, at an intermediate posi-I:ion alorl~ the tlose 50, an(~ al: a posi1,:ion adjacent the inlet of the hopper lO.
1. ~ig. ~A showx -l.h--~ case ;T) which the hopper l() wax sub,jecl,ed t,o l,he ~IIC:t,;OII e-f'-fec,t, of the vacuum pump b~lt rlo pressurize(l ai.r wi~x sllT)pLied rrom the suction nozzle.
2. 1~ig~ ~B shows the case in which the hopper 10 l~ was no~ sub,jected t,o t,he s~lct,iorl er~'ect of the vac~um pump and pressur:i.ze(i ai,r oi' lkg/cm2 was supplied from the e,jector 34 carried on the suction nozzle.
3. r~ig. ~c StlOWS the case i.n whi.ch l,he hopper lO
was sub,ject.e~ to the xuction ef'l'ect of` the vacuurn pump and the pressurize~ air of ]kg/cm2 was supplied from t;he ejector 34 carried on the xuction nozzle.
It was f'ound from this experimen-t that, the flow velocity ix re~at ive]y high on the average at ang posit,ion in t,he caxe of Fig. 8A but relative.ly low on 2~ the averag~ a1, any positi.on in the caxe of Fi~. 8~. The exp~r:imen1-. reveale~i also 1,hat, in the caxe~ of Fig. 8C, --~ 2~3~0 the flow velocity i.s relatively low at a position ::losely a(-ljacent the suct:ion nozzle but i.s sharply acoe:leral,ed from the poxiti.on ad,jacenl, the e,jector noz7,le arltl l,herl dece.l..er;lted towa d l;h, posi.tion ~d,ja-;~ cerll, I,he inle~, oi the hOppeI' 10.
~hSerV;ll,:iOrl of SIICh rlow velocity distribution re~ealed t,hal, nearet the cen-tral axi.s of the hose 50, the highe3 the llow ve.lo,it~ when the conveyance ~elicd or:ly upon 1,he suct,ion effect of the vacuu~ pump (See F;g. ~A) 7 ~nt3 that the spiral f~ow is establ.ished within t.he hose 5() when t.he conveyance relied on]y upon l,he pressul.ized air(S~e Fig. 9B).
Stab:ilizal,iol Or t,tle flow W.lS observed within the hose ~10 wherl the conveyance relied upon both the 1~ sllct,iorl effec-t of l.he vacuum pump and the pressuriY.ed a:ir.

EXPEF2IMEl\l'r (~
The suc-tion nozzles of various configuration were prepared to examine occurrence of blockages(See F:ig. IOA through 10~).
1. Fig. lOA shows the case in which the hose 50 provided wi.t,h no additional technical means was used.
~t was tound that the tabl.ets being sucked caused blocking.
2. ~ig. IOB show~ the case in which the }-ose 50 ] ~

--` Z~)~33~30 latelally provided with a pl.urality of air suetion perforations 37 was used.
:I't was l'ourlll that a E~oss.i.bilil:y of b].oc,kage is redlleed b~c,ause <L (luant-ity of air is suc,ke-l -I,h~ollgh t,hose air s~ct;ion ~erforatior1s 37 but; oeeurrence of bloekages is s:inli3al l,o the c:ase of' Fig. 10A ~o far as 1;he open end of i;he hose 50 having no perforations i.s eoneerned, si.nce t,he o;)en end c~:F the hose 50 tends to suck p.l,en1:y of tab.lets al, onee.
3. Fig. 1(3C showx the case in whieh the cap 40 provi.ded wit;h 1,he open;,ngs 41 but these oper1irlgs were not covered by t,he suct,;orl noY.Y.'Less main body, as in the presenl; .inven~;ion.
It was obser~ed -that the total opening area o~
t~ said openirlgs is t,oo large heellJse the,y are no1, eovered by the sucti.or1 nozzle's mairl ~)ody arld, as a result,, these openings tend to suck plenty of tablets at onee, callx;.ng blockage.

4. F:i.g. 1OD StlOWS the case in which the hose ~)0 is provided wi-th the eap 40 being axially slidable on l;he hose 50 to adjust ttle opening area and the loca-tions of the hose eorrespondi.ng to the respeetive openings 4:l of t,he cap 40 are prov;ded wit,h the air sueti.on perforations 37.
was found that. the suetion is smoothl~
aehîeved witho1Jt occurrenc,e of' blockages.

2~

2~ 3~

EXPERIMRNT D
Actual tablets were used to examine the convey-ing efficiency.
Thi.s e~perinlent r-evealed t,hat the nunlber oi' unacceptable tat~1et,s per l20,l)()() t,ablet,s i~ ~ero as a res~ t o the sucl,i.on corlveyarlce un(ler a suct.iorl el't'ec,t o-f ~.7 to 20kg and a pressuTi~ed air of' 1kg accordi.ng t,o the preserll; inverll;ion an(l l:tle c,orlveyarlc,e re.ly-ing onl.y uporl t,he ~ucti.on effecL y:ields 'lO unacceptab].e tab:iets per 120,000 tah:lets.
Wh:i:le l;he inventi.orl hax been particul.arLy shown arld described w:i.t,h refererlce t;o ~referred embodimellt l.hereo.l`, :it wi.L.I he l.~nderst;ood by those ~kil.le(-i in the art th.lt t,he -f'oregoing arld other changes in -form and det:ai:l.s carl l)e macle therein wi.t.hollt, departillg from th~::
spirit ~lnd scope ot' l.he inverlt,:iorl.

Claims (8)

1. A pneumatic conveyor for grainy material comprising a vacuum source such as a vacuum pump, a hopper subjected to a suction effect of the vacuum source, a suction nozzle thrown into the grainy materi-al, a hose connecting the hopper with the suction nozzle, and an ejector serving to supply pressurized air into said suction nozzle.

2. A pneumatic conveyor for grainy material as recited in Claim 1, wherein the inner surface of the hopper is formed by buffer material.

3. A pneumatic conveyor for grainy material as recited in Claim 1 or 2, wherein the hose is tangentially mounted on the side wall of the hopper.

4. A pneumatic conveyor for grainy material as recited in Claim 1, 2 or 3, wherein the ejector nozzle is so curved that a jet steam of pressurized air flows along the inner surface of the hose.

5. A suction nozzle for use in a pneumatic conveyor for grainy material comprising a cap laterally provided with openings, said cap being slidably put on an open end of the suction nozzle itself so that said cap is axially slided on said open end to adjust a total opening area of said lateral openings.

6. A suction nozzle for use in a pneumatic conveyor for grainy material as recited in Claim 5, wherein the cap is of a dual structure consisting of an outer cap and an inner cap so that these outer and inner caps may be relatively rotated to adjust the total opening area.

7. A suction nozzle for use in a pneumatic conveyor for grainy material as recited in Claim 5, wherein the suction nozzle is provided at its front end with air jet, ports from which jet streams of pressur-ized air are provided to collapse the lumps of grainy material.

8. A suction nozzle for use in a pneumatic conveyor for grainy material as recited in Claim 5, wherein locations of the suction nozzle corresponding to the respective openings of the cap are provided with air suction perforations.