CA1302144C - Material control arrangement for bulk of materials - Google Patents
Material control arrangement for bulk of materialsInfo
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- CA1302144C CA1302144C CA000591074A CA591074A CA1302144C CA 1302144 C CA1302144 C CA 1302144C CA 000591074 A CA000591074 A CA 000591074A CA 591074 A CA591074 A CA 591074A CA 1302144 C CA1302144 C CA 1302144C
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Abstract
ABSTRACT
A sensing arrangement is provided for bulk material conveying equipment such as pavers or the like, wherein the sensing arrangement comprises a non-contacting sensor fixedly mounted to the equipment, for sensing the distance between the level of the bulk material and the sensor. The remote location of the sensing device from the bulk material, such as hot asphalt in a paving machine, reduces the requirements of the sensing device to withstand extreme environmental conditions. The sensing device is thus no longer being subject to the heat of the asphalt or to abrasion from the material.
A sensing arrangement is provided for bulk material conveying equipment such as pavers or the like, wherein the sensing arrangement comprises a non-contacting sensor fixedly mounted to the equipment, for sensing the distance between the level of the bulk material and the sensor. The remote location of the sensing device from the bulk material, such as hot asphalt in a paving machine, reduces the requirements of the sensing device to withstand extreme environmental conditions. The sensing device is thus no longer being subject to the heat of the asphalt or to abrasion from the material.
Description
130;~144 . E~ 04 MATEFiIAL-~DNTF~oL--~F~Fi~NGE~ME-NT-EuF~ uL-~ OF_~fl_EF~I~L
This invention rel~tes to ~ feed control ~rr~ngentent for bul~ n)-~teri-~ls, ~nd is especi411y directed to ~rr-~ngen~ents for in,proving the feeding of rot-~ting Ib~teri-~ls~ such ls ~sph~lt or other m-~teri~ls in ro~d p~vers, wideners, etc.
While the invention will be described with p~rticul~r reference to such ~pplic~tions, it will be ~pp.~rent th-~t the concept of the invention, ~s discussed herein, is not so limited.
In ro~d p~ving equipn,ent of one type, p~ving n,~teri~l such ~5 l~sphl~lt is fed rel~rwl~rdly on the equipn,ent, for e~:~n,ple by ~ conveyor ch~in or the li~e, ~s the equipment i5 n,oved forw-~rdly l~long l~ rol~d or rol~d bed, the p~ving n,-~teri-~l being fed to l~ device for distributing the n,~teriql tr~nsversely, such l~6 ~n ~uger in the c~se of 1~ p~ving device, or ~ belt in the c-~se of ro~d widening equipn,ent. The p-~ving m-xteri-~l is deposited in front of 1 screed, which n,~y be ~
flo-~ting screed, to effect the leveling ~nd con~p~ction of the n,-lteri-~l. Typic-~l p~ving devices ~re disclosed, fnr ex-~n,ple, in U.S. F-~tent No. 3,584,547, ll~vin, ~nd typic~l rol~d wideners ~re disclosed, for e~ mple, in U-S- F-~tent No. 3,636,~31, Il-~vin et al.
1302~44 In order to enl~ble the l-~ying of ~ sn,ooth ro~d surf~ce by such equipn,ent, it is necess~ry to n,~int,~in control over the l~n,ount of ml~teril~l deposited l~long the front of the tr~nsverse feed device, such ~s ~n ~uger. The ~sphl~lt piled ~nd distribu-ted in front of the screed ,~pplies forces to the screed, c~using the screed to v~ry its level in response to the ~n,ount of n"~teri,~l distribllted thereto. It is therefore ~pp~rent th~t v~ri~tions in the height of the p~vins n,~teri,~l in front of the screed results in v,~ri,~tions in the thic~ness of p~ving n,~teri~ pplied to ,~ road sur~,lce ~nd, hence, in reduction o4 sn,oothness of the s~lrf-~ce.
This problem h~s been recognized in the p~st, l~nd ~
sollltion thereof i5 sllggested, for e~ mple, in U-S- Fl~tent No-3,678,817, M~rtenson et l~l, wherein pl~ddles ,~re n,o~nted on the p,~ving equipment ~d.j~cent e~ch side thereof, the p-~ddles riding on the surf,~ce of the ~sph~lt ~s it is conveyed to the ouger- The p~ddles ,~re coupled to ~rn,s of potention,eters, thereby providing sign-~ls responsive to the height of the p,~ving n,~teri~l ~t the p,~ddles, ~ function of the feed of p,~ving m,~teri~l to the screed. This reference discloses th~t such signl~ls n,-~y be en,ployed to control v~rious feed functions of the equipn,ent, such ~5 the speed of rot,~tion of the ~uger, the speed of n,ovement of the conveYor device conveying 13~144 ~ 04 m~teri,~l from .~ hopper to the ~luger, or controlling the ~eight of ~ g,~te to .~dJust the pern~iss.~ble thic~ness of p.~ving n~terilll on the conveyor. While~p.~ddle controlled -potention,eters of this type sin,plified the-~utonl~tic control of feed of p.~ving n,~teri.~l, to in,prove:the snoQthness of the ro4d surf~ce, they h~ve been sub.ject to prQblems~ The p~ddles, resting directly on the p~ving nll~teri41, such ~s hot ~sph.~lt or the li~e, .~re sub.ject to buildup of n~.~teri.~l ~dhering thereto, thereby resultiny in erroneous indic.~tions of the qctu.~l height of the p.~ving nl.~teri.~l in front of the screed. On occ~sion, the p.lddles n~.~y even beconle buried in the .~sph.~lt n,~teri.~l, thereby resulting in thè pro~uction of sign~ls th~t h~ve no rel~tinn to nl~teri~l thic~ness.
The problem is con,pounded when screed extensions ~re en,ployed, for es:~nlple ~s disclosed in U.S. F.~tent No.
3,702,578~ vin~ or when telescoping screeds .~re en~ployed, for ex.~nlple, .~s described in U.S. P~tent No. 4,379,b53, ~rown.
It is convention.~l to provide .~n end pl.1te .~t the sides of the screed, for n~int.~ining the level of p~ving nl~teri~l ~t the extren,ities of the screed. The sensing p~ddles, for sensing the height of the upper surf~ce of the p.~ving n,.~teri.~l, however, ,~re fis:ed to the p.~ving equipn~ent. If the screed width is reduced, it is ~pp.~rent th.~t the end pl.~tes thereof E~ 04 n,~y effect the burying of the sensing paddle in the p~ving--n"~teri.~l, by forcing paving nlaterial inwardly fron, the outer ends of the screed.
:- Paddle controlled potention,eters, directly cont~cting the-h`ot asph31t,-were~en,ployed prinlirily in`~i`èw~o~he ;i extremely adverse conditions for the sensing of the height of the top level of the asphalt. Thus, any sensing arr-~ngen,ent n,ust be capable of functioning properlY under conditions of extren,e ten,perature variation, as well as being resist~nt to ~brasion ~nd shoc~- It h-~s further been heretofor considered necessary that the sensing arrangen,ent not be sensitive to loc~l conditions other th~n the heiyht of the nlateri~l. The fact that the sensing devices are en,ployed on road n"~ing equipn,ent therebY necessitates that they be e~:tremelY rugged.
In the p~st it has been considered that, even though n"~ny other sensing ~rrangements n,~Y be useful for other applic-~tions, p-~ddle controlled potention,eters of the type-disclosed in U.S. P~tent No.3,678,817 provided the only ~a~`isfactory solution in paving equipn,ent. As above discussed, howe~er, the provision of paddles physic~lly contacting the ~sphalt, generally in regions ad.jacent the ends of the augers, does not provide an optimun, solution to the problem.
1~02i44 ~ 04 The present invention is therefore directed to the provision of ~n in,proved sensing ,~rr-~ngement for bulK n"~teri~l conveying equipment, especil~lly ro~d equipment such ,~ p.~vers, which overcon,es the ~bove discused problen,s of prior ,lrr-~ngen,ents.
~ riefly st~ted, in-~ccor~,~nce with the invention, sensing ~rr~ngen,ent is provided for bul~ n"~teri,~l conveying equipn,ent such l~5 p~vers or the li~e, wherein the sensiny qrr~ngen~ent con,prises ,~ non-cont-~cting sensor fi~edlY n,ounted to the equipn,ent, for sensing the dist~nce between the level of the bul~ n"~terinl ~nd the sensor. The ren,ote loc~tion of the sensing device fron, the bul~ ~"~teri,~l, such ~5 hot ~sphl~lt in ,1 p,~ving mqchine, reduces the requirements of the sen6ing device to withst~nd e~treme environmentl~l conditions, the sensing device thus no longer being sub.ject to the he,~t of the l~sph~lt or to ~br,~sion fron, the ml~teril~l. The provision of the ren,ote sensing device in ~ccord-~nce with the invention further prevents the outputting of erroneous control sign~ls due~ for e.-:~mple, to buildup of the n,~teri~l on the sensor, or to l~ctuql burying of the sensing device within the nll~teri~l.
Contr-~ry to previous belief, it h~s now been found th-lt non-cont,~cting sensing ~rr,~ngen,ents not only overcon,e the ,~bove discussed dis,~dv-~nt~lges of prior ,~rr~ngen,ents, but l~lso 1302144 ~-'~
provide sl~tisf-~ctory perforn,~nce under the e~:trenle1y h,~r~h environn~ent,~l conditions 1~5 re~lllired.
-- While it hns been found th~t ultr~sonic sensiny -~,~rr,~ngements ~re especi~lly useful in ,~ccord~nce with the invention, in p,~rticul~r for ro~d p,~ving equipn~ent, the invention l~lso conten,pl~tes other ren.ote sensing l~rrl~ngen~ents of ~nown types, for ex,~n-ple, emploYing light or other r~di,~tion to detern,ine the dist,nce between the sensor ~nd the p~ving n.,~teri~l, for exqnlple bY tri,~ngul.~tion. The invention thereby en,~bles the more ,~ccur,~te ~uton-~tic control of n-~teri~l height, ~nd i5 especil~lly useful in equipn~ent such ~s p~ving n~qchines wherein control of this p~r~n,èter is essenti~l in the use of the equi.pnler)t~
In order thl~t the invention n~Y be n~ore cle,~rly understood, it will now be disclosed in gre,~ter det~il with reference to the ,~ccon,p,~nying dr,~wings, wherein:
FIB. 1 is ,~ sin.plified side view of ,~ pl~ving n,~chine incorpor.~ting the invention, the p,~ving n"~chine being illustr~ted p,~rti~llY in section:
FIG. 2 is ~ sin,plified top view of ~ portion of p,~ving n"~chine with extend4ble screeJs~ lllustrl~ting the ~d~pt.~tion of the sensing ~rr.~ngen~ent of the invention to such ~ device . FIG. 3 is a sin,plified bloc~ di~gr,~nl of-,~ sensi-ng arr~ngen,ent in accord~nce with one embodin,ent of the invention, for ~pplic,~tion to a p,~ving machine: .-- -- FIG. 4 is-q-sin,plified-cross sectional view of ~
sensing he-~d thl~t n~Y be emploYed in the arr~ngen,ent~ of FIG. 3 qs well qs in the arr~ngement of FIG. 6 . . - ..;. -FIG. 5 illustrates various timing signals for thecircuit of FIG.3;
FIG. 6 is ~ n,ore detailed circuit of ,~ preferred enbodiment of the invention:
FIG. 7 illustrates various timing wl~ve fornls of the circuit of FIG. 6.
FIG. 1 illustr~tes ~ paving machine h~ving ,~ fr,~n,e 10 with a hopper 11 for receiving p~ving m~terial and ~ body 12 mounted thereon. The paving n"~chine is adapted to nlove on endless tr-~c~s 13 although it is ~pparent that it nl~Y
~lternatively be n~ounted to move on wheels (not shown). fl screed 14 is supported pivot~lly rearwl~rdlY of the fr~n~e by a screed arn, 15. Pl~ving materi~l deposited in the hopper 11 is conveyed by a conveyor (not illustrated~ in FIG. 1, to ~
tr-~nsverselY es:tending auger 16 in front of the screed, the p~ving m~teri.~l 17 being trQnsversely distributed by the ~uger 16 for con~paction in a l.~Yer of even thic~ness by the screed 130Z144 }~ ol~
14. The p~ving n"1chine illustr-1ted in FIG. 1 n,1y thus be, for ex~n,ple, ~ device of the type disclosed in U.S. F~1tent No.
3,700,~88.
In ~ccord~nce with the inventlon, ~ sensor. for e~x~mple, ~n ultr1sonic sensor 20 is mounted to the p~ving n,~chine, or screed, ~nd directed in the direction of ~rrow 21 to sense the top surf-~ce of the p-1ving n,~teril11 17. The sensor 21, which n,-~y be con,prised of ~n ultr~sonic tr~nsducer ~s will be disclosed in gre-lter det~il in the following p~r~gr-~phs, nl~y be rigidlY ~ffixed to the p-~ving nl~chine, ~nd prefer~bly sep.~r.~te such tr.~nsd-lcers .~re provided ~t e.~ch side of the p~ving n,~chine to sense the height of the top surf~ce of the p~ving m~teri-~ d.j-~cent eQch end of the ~uger 16.
While the dr~wing illustr~tes the sensing of the height of the p-1ving m-~teri-~l inlmedi-~tely to the front of the ~uger, it will be ~pp-~rent thl~t the tr~nsducer nlay be directed to sense the height of the top surf~ce of the p~ving nlQteril~l ~t ~ny other convenient loc.~tion.
The tr~nsducer ~0 is connected to provide ~n output signl11 corresponding to the tin,e of trlvel of sound wlves between the trl~nsducer ~nd the top surf~ce of the p-lving n,-~teri-~l, this dist-~nce hence constituting ~ n~e~sure of the dist-~nce between the tr~nsducer ~nd the surf~ce 22 upon which i302144 ~ 4 the paving n,~chine is driven, lnd, hence. the thic~ness of the paving n,ateri~l in front of the screed. FIG. 1 thus illustr.~tes generally the sensing arrangen,ent in accordance with the invention, and its relationship to the poving machine in general. The paving nlateri-ll piled in front of the screed ...., . .. .. . . ~ ., . ;. .~ .....
directs forces onto the screed in ~nown manner, wherebY the ~ngular orientation of the screed, and hence the thic~ness of the con,pacted layer ~3 behind the screed, n,ay v-~ry ~s a function of the an~ount of n"~terial in front of the screed~
FIG. ~ illustrates a simpiified top view of a portion of a paving n,~chine having a telescoping screed, for e~ n,ple, of the type disclosed in U.S. Patent No. 4,379,653. In this arrangen~ent the p.~ving n,aterial is conveyed on a conveyor 30, in the direction of arrow 31, to a rotl~tqble auger 3~
e~:tending trl~nsverselY of the direction of n,oven,ent ~arrow 33) of the paving n"~chine- The paving n,achine is provided with a p~ir of fi~ed n,ain screeds 34 rearwardly of the auger, ~nd ~
: .......
p.~ir of laterally nlovable screeds 35 in front of the n,ain screeds, the e~ttendable screeds being n,ovable in the directions of the arrows 36. End plates 37 are affi~:ed to the .... .
lateral extren,ities of the e~:tendable screeds. In this arr.~ngen,ent, the non-cont-~cting sensors or transdllcers 38 in qccordance with the invention ~re n,ounted above and to the 13~Z~44 front of the ends of the nuger 32, to detect the height of the pnving n..~terinl in this~ region. The control sign-~ls o~t-lined fron, the sensing devices nre employed ~o control the speed of rot~tion of the drive 39 of the ~uger ~nd/or the speed of moven,ent of the conveyor 31 nnd/or the height of ~ g-lte for pnssing mnteri~l ~long the hopper ns disclosed, for e~:ample, . -in ~-S- Pntent No. 3,678,817.
It is ~pp~rent th~t if the non-cont~cting sensors of the invention h-~d been repl-~ced bY pnving n,nteri-~l contncting p~ddles, ns in the prior nrt, inwnrd nlovement of the end pl~tes 37 would force the p.~ving mnterinl inwnrdlY .~g~inst the sensing pnddles, to effect the buri~l of the p-~ddles within the p~ving mnteri~l. The provision of the non~cont-~cting tr-~nsducer 38 of the invention, nbove the pnving mnteri-~l, elin,in~tes this problem. FIG. 2 thus illustr~tes further, in ~ sin,plified n,-~nner, the ~pplic-~tion of the non-cont-~cting sensors or tr~nsducers of the invention to 4 paving mnchine.
FIG. 3 is ~ simplified bloc~ dingrnm of one en,bodiment of ~ feed control nrrnngen~ent of the invention, especi~lly ~dnpted for n pnving m.~chine or the li~e. As illustrnted in FIG. 3, n n,~ster cloc~ 40 ~pplies tin,ing si~nnls to ~
tr-~ns~it/receive device 41 coupled to n tr-~nsducer 42. The tr~nsducer n,-~y be ~n ultr.~sonic trnnsducer- The ~ 10 --E~ 04 trQnsn,it/receive device 41 hence comprises ~ circuit responsive to the control sign-~ls fronl the m-~ster cloc~ fDr energi~ing the tr~nsducer to tr~nsn,it .~n ultr~sonic pulse.
The tr~nsn,it/receive device .~lso receives echo sign~ls . .. . . . . . .
responsive to the receipt of ultr~sonic echoes by the tr~nsducer 42, for ~pplying ~n echo responsive sign.~l to ~
logic circuit 43 by w.~y of ~ control line 44. The ultr~sonic pulses ~re directed to the p.~ving n"~teri.~l sl~ch .~s ~sph~lt 45 forw~rdly of the ~uger 46 of the plving nl~chine, so th.~t the el~psed tin,e between the pulse tr~nsmitted by the tr.~nsdllcer 42 qnd the ultr~sonic echo pulse received by the tr~nsducer 42 is ~ function of the dist.~nce between the tr~nsducer 42 ~nd the top surf-~ce of the ~sph-~lt. The tr~nsducer 42 is .~d-~pted to be fixedly nlounted to the p~ving n,~chine, or screed, so th-lt this tinle del~y is ~lso ~ n,e.~sure of the height oF the top surf.~ce of the ~sph~lt, .~nd hence of the thic~ness of the ~sph~lt l.~yer.
In order to en~ble the mounting of the tr~nsducer 4 in .~ rugged m.~nner, the tr~nsducer 42 m.~y be ~ commerci.~lly .~v.~ ble ultr-~sonic tr-~nsducer fi~edly mounted in ~n open-ended pl.~stit housing 50 for inst.~ tion .~nd support, the pl-lstic housing S~ being fixedly nlounted in ~n ~lunlinun, housing S1 for n,ech.~nicl~l strength, the hol.lsing 51 being ~302~44 3K-2ii4 shaped~as clesire~ to cnable its ready ir.ountin~3:to the paving ~achi'ne. Tl-e o?en end of the ~lasti'c~'ho'usi'ncJ S~'is'covered ~itn a layer 52 of acoustically :'tran~~'pàr'ent' foa.ti,'~rot~cted by an external layer 53 of screen wire. The transducer ~2 ~lay.be Electrostatic ~rransducer number 6~4l42 manufactured by the Polaroid Cor~oration.
Referrin~;~ again to FIC. 3, the output of tne ~aster clock 4~ is also a~plieci to a divider or counter circuit 55 for ~ro~ucins a 2lurality of timinc3 signals for the loc~ic circuits ~,3. I'he logic circuit, u~on recei~t of a si~nal either from the ~3ivider 55 or t'ne trans~it/receive device 41, signallins tt1e energization of the transducer, ?rovides a control circuit for a ra~p generator 56 to initiate a ra~?
signal. The time of the initiation of the ra~p sisnal, with respect to the time of the trans~m.it pulse, ~ay `oe controlled in order that tt;e interval c'urin~ which the ra~.p sic3nal occurs, corres?onc3 to a ~ieterl~ined ranc3e of thicknesses oL the as~halt. UFon the receipt o~ the echo si~3nal, the lo~ic circuit opens a ~ate 57 to pass the instantaneous air?litude of the ra;nn si;Jnal to an inte.;ratcr anci po~er a.~.olificr 58. r'ne lo;3ic circuit ~3 fur~her controls the su?ression of tnc ra;n?
si~;nal ~JI1en no echo is receiv2.1 witi~in a nrecletcr~ine' rar~c ot intere.;t. i~enen-~in;J upon the ti~in~J c~r)l~?y~d in the 10~ic i30Zi44 ~K-2~4 circuit, the echo signal may occur prior to the initiation of the ramp, in which case a zero or ].ow level signal is applied to the integrater. The ramp generator may hàve a maxlmum ramn level, attained after a given time following its energizàtion, so that this maximum level is passed to the integrater in response to the receipt of an echo signal after the attaining of its full level by the ramp generator.
5'his operation is illustrated in the timing diagrams of FIG. 5, wherein line A illustrates an enable signal from the master clock to the transmit/receive device 41 controlling the device 41 to transmit the ultrasonic pulse 60 as illustrated on line B. The logic circuit may develop a listen gate 61, as illustrated in line C, during which time the logic circuit 43 is responsive to the receipt of echo pulses from the device 41, as illustrated on line ~, the time 64 being a predet:ermined time following the initiation of the transmit puls~ 60.
Upon receipt of the echo signal 65, as illustrated on line D, the generation o the aforementioned ra~p signal 63 ceases as shown on line E, and the gate 57 is opened by the logic circuit 43, as illustrated by the rise at 66 of line F, to pass the then occurring signal level of the ramU to the integrater and power amplifier 58.
,:
', .. ' 1302~44 ~ 04 received sign~l over ~ nunlber of cycles~ for e~ mple, 4bout 10 pulses of ultr~sonic energy, in order to ~void erroneous output sign~ls resulting from such conditions, for e~:~mple? ~s uneven surfl~ces of the ~sph.~lt or vibr~tion of the tr~nsducer.
The intern,edi~te sign~ls ~re ~nlplified ~nd ~pplied to ~ motor speed control device 69 for controlling the ~uger motor 70 The n,otor speed control 69 m~y convention~llY constitute ~
torque n,otor on l~ servo vllver for controlling the speed of rot.~tion o4 the n)otor 70, when ~n hydr.~ulic motor is emploYed.
In the ~rr~ngement of the invention .~s illustr.~ted in fIGS. 3 ~nd 5, the r~mp 6~ is positioned in the timing di~gr~m to occur when the top of the sensed l~sph~lt is within ~
detern,ined r~nge of distl~nces fron, the tr~nsducer in which v~ri~ble speed control of the ~uger motor is to be effected.
This r.~nge m~y be, for e~:~mple, llbout 2 inches. Thus, if ~n echo sign~l is received before the initi~tion of the r~n,p, indic~ting th-~t the top of the ~sph~lt is too close to the trqnsducer, the level on line E before the initi~tion of the r~n,p is p~ssed to the i.ntegr~ter, indicl~ting th~t further m~teri~l should not be fed bY the ~uger. If the echo sign~l is received ~t the time or ~fter tl-e m-~:imum level of the r~n,p, indic~ting th~t the level of ~sph~lt is below the 2 inch control r~nge thereof, the n"~:~imum sign l level is p~ssed to ~302i44 ~ 04 the i.ntegr.~ter, ~nd the motor speed control 69 controls the n,otor to its f~stest speed r-~te. The n,otor speed control 69 n,~y, of course, ~ddition~llly be employed to control the eed of n~teriql by w~y of the conveyor. When the height~of the top of the ~sph~lt f~lls in the two inch r~nge .~s determined .
by the positioning of the r~mp 63, the sign~l p,~ssed to the integr~ter i5 intern~edi~te its m.l::imulo ~nd n,inin,um levels, thereby en~bling the v-~ri-~ble speed control of the n,otor 70 by the motor speed control device 69~
FIG. 6 illustr.~tes .~ n,ore det~iled circuit di.~gram of ~ circuit in .~ccord.lnce with the invention, oper.~tive with .
determined commerci~lly ~v~ ble ultr4sonic r~nging systen"
for controlling the feed of the bul~ m-lteri~l such ~s ~sph.~lt.
FIG. 7 illustr~tes the timing emploYed in v.lrious portions of the circuit of FIG. 6.
~ s illustr.lted in FIG. 6, ~ m.~ster cloc~ 80 of convention-~l design, h~ving ~ cloc~ frequencY. for e::~mple, of 163.84 ~ilohert~, h.~s .~n output divided bY the divider 81 to produce ~n ~ppro::im~tely 10 ~ cYle squ~rew~ve for the control of the tr.~nsducer system 82. The tr.~nsducer systen. 8~ is con,prised of ~n Electrost~tic Tr~nsducer No. 604142 produced by the Pol.lroid corpor.ltion, .~nd n r.lnging bo.~rd No. 607089, ~lso of the Fol~roid corpor~tion. This sYstem is responsive - lS -i30Z~4~
E~ 04 to the control squ~rew.lve fron, divider 81 to emit l tr~nsn,it pulse shortly 4fter the le~ding edge of the:control sign.ll.
The tr.~nsmit pulse i5 ~lbout one millisecond long .~nd consists of 4bout ~6 cycles of ~9.41 ~H~. The stlrt of this trl~nsmit sign~l is not ~ccur4tely sp4ced from:the~en~rgizing si-gn~
~pplied thereto from the divide~ 81. The XLOG output of the tr~nsducer circuit is ln lctive low sign~l st~rting 4t the beginning of the tr-~nsn,it pulse ~nd ending ~t the end of the tr~nsn,it pulse. The tr.~nsducer 82 further outputs ~ receive fl~g FLG which is ln .~ctive low sign~l responsive to the receipt of .~n echo by the trnnsducer.
hs illustr-~ted in FIG. 6, the tr.~nsmit .~nd receive outputs of the tr4nsducer 82 ~re ~pplied to the set ~nd reset inputs respectively of 1~ flip flop 83, ~nd the tr4nsn,it pulse is ~lso ~pplied to the set input of l flip flop 84. The output 85 of the flip flop 83 is set low by the tr4nsn,it pulse, to en~ble the ~pplic~tion of cloc~ pulses to the counter 86 by w4y of the NO~ g4te 87, wherebY the counter 86 st~rts counting l~t the st4rt of the tr.~nsmit pulse fron, the tr4nsducer circuit 82.. This 4rr4ngement en4bles sychroniz.ltion of the counter circuit with the tr.~nsducer, in view of the instl~bilitY of the st4rt of the trl~nsn,it pulse from the trlnsducer.
~ 16 -~302~44 I~K-2~J4 from the transducer.
- The counter 86 has a ~lurality -of outputs...as :o :..:.;.
illu.strated, correspondinc3 to divisions..by the 4th., ~-th-, 9th, l~:th:and 11th powers of two.. The~e output!s--a.re~mpl~ye~ .to control the timing in the remain~er of the.c-ircuits. The relative relationships of the c3ivide by 9th power of two to the divide by the 10th rpower of two are illustrated in the first seven lines of the timing diagrams of lIG. 7. The ~LOG
transmit ~ulse is indicated on the ~tn line of FIG. 7.
- The ram~ g~nerator of tne arrangement in FIG. 6 includes a charying capacitor 90 serially connected with a char~ing resistor 91 by way of a charginc3 diode 92 and the parallel source-(lrain ~atns of transistors 93 and ~4. The voltage across the charging ca?acitor 9~ is applie~ to an integrator circuit 95 by way o~ the source-drain path of transistor 96, anu the capacitor 9~ is shunted to grounc3 by way oE the source-drain ath of transistor 97.
In order to more fully understand the ol~eration oE the circuit of FIG. 6, it will initially be explained that it is desirable to be able to receive an echo pulse, in one e~bodi;nent of the invention, in tlle ranye of s~acings from 4 inches to 42 inches from the transclucer, anci not ~o receive echoes from tar(3ets outside of this range. It is further i302i44 i-~K-2 desiral~le to control the au~er so that it does not feed asphalt when the detected top surface of 'the asphalt-is closer ~han about 16.15 inches from the transducer, to control- the auc3er at its full speed when the distance ~etween the top of the asphalt and the transducer is about 18.15 inches or ~reater, and to have proportionately intermediate speeds or detected levels of the top of the asphalt within this range of a'oout 2 inches. The voltac3e across the capacitor 9~, which is passed to the inte~rater 95, then must be zero if an echo signal occurs indicatinc3 a distance less than 16.15 inches, and ,~ust have a maxi:num value at the ti.~e correspon~ing to a distance of about 18.15 inches or ~reater. ~ccordincJly, the charcJing resistor 91 and the capacitor 9~ are selected to have an RC value permitting this char~3inc3 rate.
ReferrincJ aCJain to E'IG. 6, the receive output of the transducer 82 is normally high, and goes low upon the receipt of an ecno siynal, to reset the flip flop 83. Irhe resultant hi~h level at the output ~5 of the flip flop 83 ~loc~s the ~IOR
3ate 87 to stop countinc3 in the counter, resets the counter, and renders the transistor 96 conductive to ~ass the charge of the charcJing capacitor 90 to the intecJrator 95.
The generation of a ramn is controlled by the transistor 93, which, as indicated, occurs in response to - 1~3 -1302~4 ~ 2~4 positive levels of the divide ~y the 8th and 9th powers of two of the clock signal. ~s apparent in FIG. 7, the second occurrence of this coincidence occurs at a time corresponding to a spacing of 16.15 inches, and hence the transistor 93 is rendered conductive at this time to enable the charging of the capacitor 90. The flip flop 8~ is employed in order to bloc~
charging of the capacitor at the first occurrence of this coincidence, and during the transmit pulse, by holding the capacitor at lo~ level by way of the diode 98 at the output of the flip flop 84. Thus, tne capacitor voltage 90 cannot rise from the time that the flip flop 84 is set by the transmit pulse, until the time that the divide by the eighth power of two signal goes low when the divide by 2 to the 10th power signal is low (at about 1.6 milliseconds from the start of the transmit pulse).
The minimum time at which the system can respond to a receive or echo pulse is deterrnined by the transducer itsel~, and corresponds to about ~.G milliseconds (about 4 to 5 inches). An echo pulse received anytime subsequent to this time results in the resetting of the flip flop 83, tne stop~ing of the counter, the resetting of the counter and the passing of the charge on the capacitor 50 to the integrator 9S
as discussed.
-- lg --1~02i44 o~
subst~nti~lly its full ch~rging v~lue in ,~ tin,e period corresponding to ~bout 2 inches of sp.lce.
While, in 4ccord~nce with the invention, the r.~n,p nl~Y
constitute . continuous ch~rging of the c~p.~citor 90, it is preferred th4t the c~p~citor be ch~rged in steps, to:h.~ve :
pl~te~u intern,edi4te the steps, 4s illustr.lted by the r~n,p 100 in the 9th line of FIG. 7. Thus, .~s illustr4ted in FI~. 6, the ch~rging volt4ge the c4p4citor is the divide by the 4th power of two output of the col~nter. This results in the ch4rging of the c~p,~citor in 4bout 4 steps, e.~ch corresponding to ~bout one qu.~rter of the full height of the r~nlp.
In Q preferred enlbodin,ent of the invention, it is desir4ble to be 4ble to re.~dily ch.~nge the tin~e of initi.~tion of the r~n,p, in order to en4ble either control of the top of the .~sph~lt lt .~ different level, or its sin,ple .~pplic.~tion of the tr4nsducer to different types of equipn,ent. for this purpose, the g~te of the tr.~nsistor ~3 is held low by w~y of the diode 110 ~nd resistor 111 by the closing of 4 selection switch 112. The g~te of the tr.~nsistor ~4 is energi~ed by the divide by the 10th pow~r of two output of the counter, whereby the tr4nsistor ~4 is rendered conductive initi411Y 4t 4 tin,e corresponding to .l sp.~cing fron~ the tr-lnsducer of 21.42 inches, providing the r~n~p 1~0, ~s illustr~ted in the l~st 13021A4 ~ ~o~
line of FIG. 7.
The integr~ter 95 is con,prised of ~ convention~l integr-~ted circuit h~ving circuit-component6.en-~bling -the.;... :.
integr~ion of input sign~ls for .~ peri.od of ~bout 1 second,.
corres~onding to .~bout:10 cYcles of:the ultr~son~ic systenl~-the output of the integr~ter 9S is-~pp.lied to ~ tr~n~istor.
power ~mplifier 116 supplied by ~ const-~nt current source 117 of convention~l construction. The tr~nsistor ~n~plifier 116 is provided with ~ p-~r-~llel ~C feedb.~c~ networ~ 118 to provide f~st response slow dec-~Y ch~r~cteristics, .~nd ~ diode 120 m4y be connected in series with the collector resistor for spi~ed protection. The outpllt of the ~n~plifier 116 is directed to the servo v~lve 130, of convention~l construction. for control of the .~uger nlotor 131.
The devices en~ployed in the circuit of FIG. 6 ~re convention~ nd it n~.~y be convention~l CMOS devices. The tr~nsistors enlployed in the timing control.circuitrY nl.~y constitute convention~l tr~nsnlission gl~tesr ~nd the counter 86 ~nd divider 81 4re convention~l CMOS devices.
The c.~p.~citor ~0 i5 disch.~rged everY cycle of the ultr~sonic pulse, when no echo is received within r~nge of interest, by the divide by the 11th power of 2 sign~l, bY the tr~nsistor 97.
i3~2~44 ~-204 While it is preferred th~t the tr.lnsducer be ~n ultrQsonic trqnsducer for ~pplic.~tions where high he~t c-ln be expected in the n,~teri~l to be distr.ibuted, such ~5 ~sph~lt p.~ving m.lteri41s, it is .~pp.~rent th~t the concept of:the -i*~ention is ~lso qpplic~ble to other~tr~ns-d~cer dë~ices, such ~s pie~o electric devices. Further, in ~ccord~nce-with the invention, it i5 ~pp~rent thqt other dist~nce me~suring ~rr~ngements m~y be employed, such.-~s tri~ngul-~tion devices employing v.~rious forn,s of r~di.~tion. It is still further ~pp.lrent th-lt me.~ns .lre prefer~bly provided for overriding the qutom~tic control of the invention for m~nu~l oper.~tion. in the event thqt ~utom.~tic'control is not desired. This m.~y be effected by conventional devices, for e~.~mple, upon the dis~blement of the circuit of the invention. It is of course further ~pp~rent th~t the output of the circuit c4n be en,ployed, inste.~d of or in .~ddition to ~utom~tic~llY
controlling the ~uger 4nd/or conveYor feed, to control ~n indic~tor~ wherebY ~n oper~tor n,~y view such indic~tor to effect the m~nu~l control of the feed.
~ n electronic tr~nsducer of the ~bove disclosed tYpe provides the .~dv.lnt.~ge of subst.~nti.~l inlm'nity to e~ttern~l influences, since the tr4nsducer is direction.~l. The immunity is incre-~sed bY inhibiting ~ny response to sign~ls received ` 1302i44 ~ 04 fron~ dist.~nces gre~ter th~t 4bout 40 inches. The device i5 hence subst.~nti.~llY in,n.une to control by humps or ridges in .
the:surf~ce being p~ved, n,~teri~l spilled from-the:truc~.or hopper, or n,.~teri.~l pulled in bY n~rrowing of the p~ving-width.~ The tr~nsducer n.~y be mounted ~t-~ loc~tion wher.e it :-does not interfere with inst~ tion or remov~l o~ con,ponents of the p~ving m~chine. The circuit of the invention is .~lso re~dily ~d~ptc~ble to .~uton~tic or remote control of n~.lteri.~l feed.
. It is q further adv~nt~geous fe.~ture of the invention th~t the .~uger or other feed device controlled bY the sYsten is turned off when the first echo received corresponds.to Q
dist.~nce of .~bout 16 inches or less, corresponding to .~n over supply of .~sph~lt . This fe~ture thereby renders the sYsten, oper.~tive to shut off the ~uger in the event of other ob.jects between the luger ~nd the tr~nsducer~ .~nd c.~n prevent in.jury to oper.~ting personnel if theY .~re intention-~llY or ~ccident~lly present in this sp~ce, by effecting the turning off of the ~uger.
While the invention h-~s been disclosed ~nd described with reference to .~ linlitecl nun~ber of en,bodin,ents, it is 1pp-~rent th~t v.~ri.ltions .~nd n,odific.~tions n~y be nl.~de therein, .~nd it is therefore intended in the following cl~ims ~30214A
~ 04 to cover el~ch such vllri,~tion ,lnd modific~tion ~s follows within the spirit qnd scope of the invention.
: . .
This invention rel~tes to ~ feed control ~rr~ngentent for bul~ n)-~teri-~ls, ~nd is especi411y directed to ~rr-~ngen~ents for in,proving the feeding of rot-~ting Ib~teri-~ls~ such ls ~sph~lt or other m-~teri~ls in ro~d p~vers, wideners, etc.
While the invention will be described with p~rticul~r reference to such ~pplic~tions, it will be ~pp.~rent th-~t the concept of the invention, ~s discussed herein, is not so limited.
In ro~d p~ving equipn,ent of one type, p~ving n,~teri~l such ~5 l~sphl~lt is fed rel~rwl~rdly on the equipn,ent, for e~:~n,ple by ~ conveyor ch~in or the li~e, ~s the equipment i5 n,oved forw-~rdly l~long l~ rol~d or rol~d bed, the p~ving n,-~teri-~l being fed to l~ device for distributing the n,~teriql tr~nsversely, such l~6 ~n ~uger in the c~se of 1~ p~ving device, or ~ belt in the c-~se of ro~d widening equipn,ent. The p-~ving m-xteri-~l is deposited in front of 1 screed, which n,~y be ~
flo-~ting screed, to effect the leveling ~nd con~p~ction of the n,-lteri-~l. Typic-~l p~ving devices ~re disclosed, fnr ex-~n,ple, in U.S. F-~tent No. 3,584,547, ll~vin, ~nd typic~l rol~d wideners ~re disclosed, for e~ mple, in U-S- F-~tent No. 3,636,~31, Il-~vin et al.
1302~44 In order to enl~ble the l-~ying of ~ sn,ooth ro~d surf~ce by such equipn,ent, it is necess~ry to n,~int,~in control over the l~n,ount of ml~teril~l deposited l~long the front of the tr~nsverse feed device, such ~s ~n ~uger. The ~sphl~lt piled ~nd distribu-ted in front of the screed ,~pplies forces to the screed, c~using the screed to v~ry its level in response to the ~n,ount of n"~teri,~l distribllted thereto. It is therefore ~pp~rent th~t v~ri~tions in the height of the p~vins n,~teri,~l in front of the screed results in v,~ri,~tions in the thic~ness of p~ving n,~teri~ pplied to ,~ road sur~,lce ~nd, hence, in reduction o4 sn,oothness of the s~lrf-~ce.
This problem h~s been recognized in the p~st, l~nd ~
sollltion thereof i5 sllggested, for e~ mple, in U-S- Fl~tent No-3,678,817, M~rtenson et l~l, wherein pl~ddles ,~re n,o~nted on the p,~ving equipment ~d.j~cent e~ch side thereof, the p-~ddles riding on the surf,~ce of the ~sph~lt ~s it is conveyed to the ouger- The p~ddles ,~re coupled to ~rn,s of potention,eters, thereby providing sign-~ls responsive to the height of the p,~ving n,~teri~l ~t the p,~ddles, ~ function of the feed of p,~ving m,~teri~l to the screed. This reference discloses th~t such signl~ls n,-~y be en,ployed to control v~rious feed functions of the equipn,ent, such ~5 the speed of rot,~tion of the ~uger, the speed of n,ovement of the conveYor device conveying 13~144 ~ 04 m~teri,~l from .~ hopper to the ~luger, or controlling the ~eight of ~ g,~te to .~dJust the pern~iss.~ble thic~ness of p.~ving n~terilll on the conveyor. While~p.~ddle controlled -potention,eters of this type sin,plified the-~utonl~tic control of feed of p.~ving n,~teri.~l, to in,prove:the snoQthness of the ro4d surf~ce, they h~ve been sub.ject to prQblems~ The p~ddles, resting directly on the p~ving nll~teri41, such ~s hot ~sph.~lt or the li~e, .~re sub.ject to buildup of n~.~teri.~l ~dhering thereto, thereby resultiny in erroneous indic.~tions of the qctu.~l height of the p.~ving nl.~teri.~l in front of the screed. On occ~sion, the p.lddles n~.~y even beconle buried in the .~sph.~lt n,~teri.~l, thereby resulting in thè pro~uction of sign~ls th~t h~ve no rel~tinn to nl~teri~l thic~ness.
The problem is con,pounded when screed extensions ~re en,ployed, for es:~nlple ~s disclosed in U.S. F.~tent No.
3,702,578~ vin~ or when telescoping screeds .~re en~ployed, for ex.~nlple, .~s described in U.S. P~tent No. 4,379,b53, ~rown.
It is convention.~l to provide .~n end pl.1te .~t the sides of the screed, for n~int.~ining the level of p~ving nl~teri~l ~t the extren,ities of the screed. The sensing p~ddles, for sensing the height of the upper surf~ce of the p.~ving n,.~teri.~l, however, ,~re fis:ed to the p.~ving equipn~ent. If the screed width is reduced, it is ~pp.~rent th.~t the end pl.~tes thereof E~ 04 n,~y effect the burying of the sensing paddle in the p~ving--n"~teri.~l, by forcing paving nlaterial inwardly fron, the outer ends of the screed.
:- Paddle controlled potention,eters, directly cont~cting the-h`ot asph31t,-were~en,ployed prinlirily in`~i`èw~o~he ;i extremely adverse conditions for the sensing of the height of the top level of the asphalt. Thus, any sensing arr-~ngen,ent n,ust be capable of functioning properlY under conditions of extren,e ten,perature variation, as well as being resist~nt to ~brasion ~nd shoc~- It h-~s further been heretofor considered necessary that the sensing arrangen,ent not be sensitive to loc~l conditions other th~n the heiyht of the nlateri~l. The fact that the sensing devices are en,ployed on road n"~ing equipn,ent therebY necessitates that they be e~:tremelY rugged.
In the p~st it has been considered that, even though n"~ny other sensing ~rrangements n,~Y be useful for other applic-~tions, p-~ddle controlled potention,eters of the type-disclosed in U.S. P~tent No.3,678,817 provided the only ~a~`isfactory solution in paving equipn,ent. As above discussed, howe~er, the provision of paddles physic~lly contacting the ~sphalt, generally in regions ad.jacent the ends of the augers, does not provide an optimun, solution to the problem.
1~02i44 ~ 04 The present invention is therefore directed to the provision of ~n in,proved sensing ,~rr-~ngement for bulK n"~teri~l conveying equipment, especil~lly ro~d equipment such ,~ p.~vers, which overcon,es the ~bove discused problen,s of prior ,lrr-~ngen,ents.
~ riefly st~ted, in-~ccor~,~nce with the invention, sensing ~rr~ngen,ent is provided for bul~ n"~teri,~l conveying equipn,ent such l~5 p~vers or the li~e, wherein the sensiny qrr~ngen~ent con,prises ,~ non-cont-~cting sensor fi~edlY n,ounted to the equipn,ent, for sensing the dist~nce between the level of the bul~ n"~terinl ~nd the sensor. The ren,ote loc~tion of the sensing device fron, the bul~ ~"~teri,~l, such ~5 hot ~sphl~lt in ,1 p,~ving mqchine, reduces the requirements of the sen6ing device to withst~nd e~treme environmentl~l conditions, the sensing device thus no longer being sub.ject to the he,~t of the l~sph~lt or to ~br,~sion fron, the ml~teril~l. The provision of the ren,ote sensing device in ~ccord-~nce with the invention further prevents the outputting of erroneous control sign~ls due~ for e.-:~mple, to buildup of the n,~teri~l on the sensor, or to l~ctuql burying of the sensing device within the nll~teri~l.
Contr-~ry to previous belief, it h~s now been found th-lt non-cont,~cting sensing ~rr,~ngen,ents not only overcon,e the ,~bove discussed dis,~dv-~nt~lges of prior ,~rr~ngen,ents, but l~lso 1302144 ~-'~
provide sl~tisf-~ctory perforn,~nce under the e~:trenle1y h,~r~h environn~ent,~l conditions 1~5 re~lllired.
-- While it hns been found th~t ultr~sonic sensiny -~,~rr,~ngements ~re especi~lly useful in ,~ccord~nce with the invention, in p,~rticul~r for ro~d p,~ving equipn~ent, the invention l~lso conten,pl~tes other ren.ote sensing l~rrl~ngen~ents of ~nown types, for ex,~n-ple, emploYing light or other r~di,~tion to detern,ine the dist,nce between the sensor ~nd the p~ving n.,~teri~l, for exqnlple bY tri,~ngul.~tion. The invention thereby en,~bles the more ,~ccur,~te ~uton-~tic control of n-~teri~l height, ~nd i5 especil~lly useful in equipn~ent such ~s p~ving n~qchines wherein control of this p~r~n,èter is essenti~l in the use of the equi.pnler)t~
In order thl~t the invention n~Y be n~ore cle,~rly understood, it will now be disclosed in gre,~ter det~il with reference to the ,~ccon,p,~nying dr,~wings, wherein:
FIB. 1 is ,~ sin.plified side view of ,~ pl~ving n,~chine incorpor.~ting the invention, the p,~ving n"~chine being illustr~ted p,~rti~llY in section:
FIG. 2 is ~ sin,plified top view of ~ portion of p,~ving n"~chine with extend4ble screeJs~ lllustrl~ting the ~d~pt.~tion of the sensing ~rr.~ngen~ent of the invention to such ~ device . FIG. 3 is a sin,plified bloc~ di~gr,~nl of-,~ sensi-ng arr~ngen,ent in accord~nce with one embodin,ent of the invention, for ~pplic,~tion to a p,~ving machine: .-- -- FIG. 4 is-q-sin,plified-cross sectional view of ~
sensing he-~d thl~t n~Y be emploYed in the arr~ngen,ent~ of FIG. 3 qs well qs in the arr~ngement of FIG. 6 . . - ..;. -FIG. 5 illustrates various timing signals for thecircuit of FIG.3;
FIG. 6 is ~ n,ore detailed circuit of ,~ preferred enbodiment of the invention:
FIG. 7 illustrates various timing wl~ve fornls of the circuit of FIG. 6.
FIG. 1 illustr~tes ~ paving machine h~ving ,~ fr,~n,e 10 with a hopper 11 for receiving p~ving m~terial and ~ body 12 mounted thereon. The paving n"~chine is adapted to nlove on endless tr-~c~s 13 although it is ~pparent that it nl~Y
~lternatively be n~ounted to move on wheels (not shown). fl screed 14 is supported pivot~lly rearwl~rdlY of the fr~n~e by a screed arn, 15. Pl~ving materi~l deposited in the hopper 11 is conveyed by a conveyor (not illustrated~ in FIG. 1, to ~
tr-~nsverselY es:tending auger 16 in front of the screed, the p~ving m~teri.~l 17 being trQnsversely distributed by the ~uger 16 for con~paction in a l.~Yer of even thic~ness by the screed 130Z144 }~ ol~
14. The p~ving n"1chine illustr-1ted in FIG. 1 n,1y thus be, for ex~n,ple, ~ device of the type disclosed in U.S. F~1tent No.
3,700,~88.
In ~ccord~nce with the inventlon, ~ sensor. for e~x~mple, ~n ultr1sonic sensor 20 is mounted to the p~ving n,~chine, or screed, ~nd directed in the direction of ~rrow 21 to sense the top surf-~ce of the p-1ving n,~teril11 17. The sensor 21, which n,-~y be con,prised of ~n ultr~sonic tr~nsducer ~s will be disclosed in gre-lter det~il in the following p~r~gr-~phs, nl~y be rigidlY ~ffixed to the p-~ving nl~chine, ~nd prefer~bly sep.~r.~te such tr.~nsd-lcers .~re provided ~t e.~ch side of the p~ving n,~chine to sense the height of the top surf~ce of the p~ving m~teri-~ d.j-~cent eQch end of the ~uger 16.
While the dr~wing illustr~tes the sensing of the height of the p-1ving m-~teri-~l inlmedi-~tely to the front of the ~uger, it will be ~pp-~rent thl~t the tr~nsducer nlay be directed to sense the height of the top surf~ce of the p~ving nlQteril~l ~t ~ny other convenient loc.~tion.
The tr~nsducer ~0 is connected to provide ~n output signl11 corresponding to the tin,e of trlvel of sound wlves between the trl~nsducer ~nd the top surf~ce of the p-lving n,-~teri-~l, this dist-~nce hence constituting ~ n~e~sure of the dist-~nce between the tr~nsducer ~nd the surf~ce 22 upon which i302144 ~ 4 the paving n,~chine is driven, lnd, hence. the thic~ness of the paving n,ateri~l in front of the screed. FIG. 1 thus illustr.~tes generally the sensing arrangen,ent in accordance with the invention, and its relationship to the poving machine in general. The paving nlateri-ll piled in front of the screed ...., . .. .. . . ~ ., . ;. .~ .....
directs forces onto the screed in ~nown manner, wherebY the ~ngular orientation of the screed, and hence the thic~ness of the con,pacted layer ~3 behind the screed, n,ay v-~ry ~s a function of the an~ount of n"~terial in front of the screed~
FIG. ~ illustrates a simpiified top view of a portion of a paving n,~chine having a telescoping screed, for e~ n,ple, of the type disclosed in U.S. Patent No. 4,379,653. In this arrangen~ent the p.~ving n,aterial is conveyed on a conveyor 30, in the direction of arrow 31, to a rotl~tqble auger 3~
e~:tending trl~nsverselY of the direction of n,oven,ent ~arrow 33) of the paving n"~chine- The paving n,achine is provided with a p~ir of fi~ed n,ain screeds 34 rearwardly of the auger, ~nd ~
: .......
p.~ir of laterally nlovable screeds 35 in front of the n,ain screeds, the e~ttendable screeds being n,ovable in the directions of the arrows 36. End plates 37 are affi~:ed to the .... .
lateral extren,ities of the e~:tendable screeds. In this arr.~ngen,ent, the non-cont-~cting sensors or transdllcers 38 in qccordance with the invention ~re n,ounted above and to the 13~Z~44 front of the ends of the nuger 32, to detect the height of the pnving n..~terinl in this~ region. The control sign-~ls o~t-lined fron, the sensing devices nre employed ~o control the speed of rot~tion of the drive 39 of the ~uger ~nd/or the speed of moven,ent of the conveyor 31 nnd/or the height of ~ g-lte for pnssing mnteri~l ~long the hopper ns disclosed, for e~:ample, . -in ~-S- Pntent No. 3,678,817.
It is ~pp~rent th~t if the non-cont~cting sensors of the invention h-~d been repl-~ced bY pnving n,nteri-~l contncting p~ddles, ns in the prior nrt, inwnrd nlovement of the end pl~tes 37 would force the p.~ving mnterinl inwnrdlY .~g~inst the sensing pnddles, to effect the buri~l of the p-~ddles within the p~ving mnteri~l. The provision of the non~cont-~cting tr-~nsducer 38 of the invention, nbove the pnving mnteri-~l, elin,in~tes this problem. FIG. 2 thus illustr~tes further, in ~ sin,plified n,-~nner, the ~pplic-~tion of the non-cont-~cting sensors or tr~nsducers of the invention to 4 paving mnchine.
FIG. 3 is ~ simplified bloc~ dingrnm of one en,bodiment of ~ feed control nrrnngen~ent of the invention, especi~lly ~dnpted for n pnving m.~chine or the li~e. As illustrnted in FIG. 3, n n,~ster cloc~ 40 ~pplies tin,ing si~nnls to ~
tr-~ns~it/receive device 41 coupled to n tr-~nsducer 42. The tr~nsducer n,-~y be ~n ultr.~sonic trnnsducer- The ~ 10 --E~ 04 trQnsn,it/receive device 41 hence comprises ~ circuit responsive to the control sign-~ls fronl the m-~ster cloc~ fDr energi~ing the tr~nsducer to tr~nsn,it .~n ultr~sonic pulse.
The tr~nsn,it/receive device .~lso receives echo sign~ls . .. . . . . . .
responsive to the receipt of ultr~sonic echoes by the tr~nsducer 42, for ~pplying ~n echo responsive sign.~l to ~
logic circuit 43 by w.~y of ~ control line 44. The ultr~sonic pulses ~re directed to the p.~ving n"~teri.~l sl~ch .~s ~sph~lt 45 forw~rdly of the ~uger 46 of the plving nl~chine, so th.~t the el~psed tin,e between the pulse tr~nsmitted by the tr.~nsdllcer 42 qnd the ultr~sonic echo pulse received by the tr~nsducer 42 is ~ function of the dist.~nce between the tr~nsducer 42 ~nd the top surf-~ce of the ~sph-~lt. The tr~nsducer 42 is .~d-~pted to be fixedly nlounted to the p~ving n,~chine, or screed, so th-lt this tinle del~y is ~lso ~ n,e.~sure of the height oF the top surf.~ce of the ~sph~lt, .~nd hence of the thic~ness of the ~sph~lt l.~yer.
In order to en~ble the mounting of the tr~nsducer 4 in .~ rugged m.~nner, the tr~nsducer 42 m.~y be ~ commerci.~lly .~v.~ ble ultr-~sonic tr-~nsducer fi~edly mounted in ~n open-ended pl.~stit housing 50 for inst.~ tion .~nd support, the pl-lstic housing S~ being fixedly nlounted in ~n ~lunlinun, housing S1 for n,ech.~nicl~l strength, the hol.lsing 51 being ~302~44 3K-2ii4 shaped~as clesire~ to cnable its ready ir.ountin~3:to the paving ~achi'ne. Tl-e o?en end of the ~lasti'c~'ho'usi'ncJ S~'is'covered ~itn a layer 52 of acoustically :'tran~~'pàr'ent' foa.ti,'~rot~cted by an external layer 53 of screen wire. The transducer ~2 ~lay.be Electrostatic ~rransducer number 6~4l42 manufactured by the Polaroid Cor~oration.
Referrin~;~ again to FIC. 3, the output of tne ~aster clock 4~ is also a~plieci to a divider or counter circuit 55 for ~ro~ucins a 2lurality of timinc3 signals for the loc~ic circuits ~,3. I'he logic circuit, u~on recei~t of a si~nal either from the ~3ivider 55 or t'ne trans~it/receive device 41, signallins tt1e energization of the transducer, ?rovides a control circuit for a ra~p generator 56 to initiate a ra~?
signal. The time of the initiation of the ra~p sisnal, with respect to the time of the trans~m.it pulse, ~ay `oe controlled in order that tt;e interval c'urin~ which the ra~.p sic3nal occurs, corres?onc3 to a ~ieterl~ined ranc3e of thicknesses oL the as~halt. UFon the receipt o~ the echo si~3nal, the lo~ic circuit opens a ~ate 57 to pass the instantaneous air?litude of the ra;nn si;Jnal to an inte.;ratcr anci po~er a.~.olificr 58. r'ne lo;3ic circuit ~3 fur~her controls the su?ression of tnc ra;n?
si~;nal ~JI1en no echo is receiv2.1 witi~in a nrecletcr~ine' rar~c ot intere.;t. i~enen-~in;J upon the ti~in~J c~r)l~?y~d in the 10~ic i30Zi44 ~K-2~4 circuit, the echo signal may occur prior to the initiation of the ramp, in which case a zero or ].ow level signal is applied to the integrater. The ramp generator may hàve a maxlmum ramn level, attained after a given time following its energizàtion, so that this maximum level is passed to the integrater in response to the receipt of an echo signal after the attaining of its full level by the ramp generator.
5'his operation is illustrated in the timing diagrams of FIG. 5, wherein line A illustrates an enable signal from the master clock to the transmit/receive device 41 controlling the device 41 to transmit the ultrasonic pulse 60 as illustrated on line B. The logic circuit may develop a listen gate 61, as illustrated in line C, during which time the logic circuit 43 is responsive to the receipt of echo pulses from the device 41, as illustrated on line ~, the time 64 being a predet:ermined time following the initiation of the transmit puls~ 60.
Upon receipt of the echo signal 65, as illustrated on line D, the generation o the aforementioned ra~p signal 63 ceases as shown on line E, and the gate 57 is opened by the logic circuit 43, as illustrated by the rise at 66 of line F, to pass the then occurring signal level of the ramU to the integrater and power amplifier 58.
,:
', .. ' 1302~44 ~ 04 received sign~l over ~ nunlber of cycles~ for e~ mple, 4bout 10 pulses of ultr~sonic energy, in order to ~void erroneous output sign~ls resulting from such conditions, for e~:~mple? ~s uneven surfl~ces of the ~sph.~lt or vibr~tion of the tr~nsducer.
The intern,edi~te sign~ls ~re ~nlplified ~nd ~pplied to ~ motor speed control device 69 for controlling the ~uger motor 70 The n,otor speed control 69 m~y convention~llY constitute ~
torque n,otor on l~ servo vllver for controlling the speed of rot.~tion o4 the n)otor 70, when ~n hydr.~ulic motor is emploYed.
In the ~rr~ngement of the invention .~s illustr.~ted in fIGS. 3 ~nd 5, the r~mp 6~ is positioned in the timing di~gr~m to occur when the top of the sensed l~sph~lt is within ~
detern,ined r~nge of distl~nces fron, the tr~nsducer in which v~ri~ble speed control of the ~uger motor is to be effected.
This r.~nge m~y be, for e~:~mple, llbout 2 inches. Thus, if ~n echo sign~l is received before the initi~tion of the r~n,p, indic~ting th-~t the top of the ~sph~lt is too close to the trqnsducer, the level on line E before the initi~tion of the r~n,p is p~ssed to the i.ntegr~ter, indicl~ting th~t further m~teri~l should not be fed bY the ~uger. If the echo sign~l is received ~t the time or ~fter tl-e m-~:imum level of the r~n,p, indic~ting th~t the level of ~sph~lt is below the 2 inch control r~nge thereof, the n"~:~imum sign l level is p~ssed to ~302i44 ~ 04 the i.ntegr.~ter, ~nd the motor speed control 69 controls the n,otor to its f~stest speed r-~te. The n,otor speed control 69 n,~y, of course, ~ddition~llly be employed to control the eed of n~teriql by w~y of the conveyor. When the height~of the top of the ~sph~lt f~lls in the two inch r~nge .~s determined .
by the positioning of the r~mp 63, the sign~l p,~ssed to the integr~ter i5 intern~edi~te its m.l::imulo ~nd n,inin,um levels, thereby en~bling the v-~ri-~ble speed control of the n,otor 70 by the motor speed control device 69~
FIG. 6 illustr.~tes .~ n,ore det~iled circuit di.~gram of ~ circuit in .~ccord.lnce with the invention, oper.~tive with .
determined commerci~lly ~v~ ble ultr4sonic r~nging systen"
for controlling the feed of the bul~ m-lteri~l such ~s ~sph.~lt.
FIG. 7 illustr~tes the timing emploYed in v.lrious portions of the circuit of FIG. 6.
~ s illustr.lted in FIG. 6, ~ m.~ster cloc~ 80 of convention-~l design, h~ving ~ cloc~ frequencY. for e::~mple, of 163.84 ~ilohert~, h.~s .~n output divided bY the divider 81 to produce ~n ~ppro::im~tely 10 ~ cYle squ~rew~ve for the control of the tr.~nsducer system 82. The tr.~nsducer systen. 8~ is con,prised of ~n Electrost~tic Tr~nsducer No. 604142 produced by the Pol.lroid corpor.ltion, .~nd n r.lnging bo.~rd No. 607089, ~lso of the Fol~roid corpor~tion. This sYstem is responsive - lS -i30Z~4~
E~ 04 to the control squ~rew.lve fron, divider 81 to emit l tr~nsn,it pulse shortly 4fter the le~ding edge of the:control sign.ll.
The tr.~nsmit pulse i5 ~lbout one millisecond long .~nd consists of 4bout ~6 cycles of ~9.41 ~H~. The stlrt of this trl~nsmit sign~l is not ~ccur4tely sp4ced from:the~en~rgizing si-gn~
~pplied thereto from the divide~ 81. The XLOG output of the tr~nsducer circuit is ln lctive low sign~l st~rting 4t the beginning of the tr-~nsn,it pulse ~nd ending ~t the end of the tr~nsn,it pulse. The tr.~nsducer 82 further outputs ~ receive fl~g FLG which is ln .~ctive low sign~l responsive to the receipt of .~n echo by the trnnsducer.
hs illustr-~ted in FIG. 6, the tr.~nsmit .~nd receive outputs of the tr4nsducer 82 ~re ~pplied to the set ~nd reset inputs respectively of 1~ flip flop 83, ~nd the tr4nsn,it pulse is ~lso ~pplied to the set input of l flip flop 84. The output 85 of the flip flop 83 is set low by the tr4nsn,it pulse, to en~ble the ~pplic~tion of cloc~ pulses to the counter 86 by w4y of the NO~ g4te 87, wherebY the counter 86 st~rts counting l~t the st4rt of the tr.~nsmit pulse fron, the tr4nsducer circuit 82.. This 4rr4ngement en4bles sychroniz.ltion of the counter circuit with the tr.~nsducer, in view of the instl~bilitY of the st4rt of the trl~nsn,it pulse from the trlnsducer.
~ 16 -~302~44 I~K-2~J4 from the transducer.
- The counter 86 has a ~lurality -of outputs...as :o :..:.;.
illu.strated, correspondinc3 to divisions..by the 4th., ~-th-, 9th, l~:th:and 11th powers of two.. The~e output!s--a.re~mpl~ye~ .to control the timing in the remain~er of the.c-ircuits. The relative relationships of the c3ivide by 9th power of two to the divide by the 10th rpower of two are illustrated in the first seven lines of the timing diagrams of lIG. 7. The ~LOG
transmit ~ulse is indicated on the ~tn line of FIG. 7.
- The ram~ g~nerator of tne arrangement in FIG. 6 includes a charying capacitor 90 serially connected with a char~ing resistor 91 by way of a charginc3 diode 92 and the parallel source-(lrain ~atns of transistors 93 and ~4. The voltage across the charging ca?acitor 9~ is applie~ to an integrator circuit 95 by way o~ the source-drain path of transistor 96, anu the capacitor 9~ is shunted to grounc3 by way oE the source-drain ath of transistor 97.
In order to more fully understand the ol~eration oE the circuit of FIG. 6, it will initially be explained that it is desirable to be able to receive an echo pulse, in one e~bodi;nent of the invention, in tlle ranye of s~acings from 4 inches to 42 inches from the transclucer, anci not ~o receive echoes from tar(3ets outside of this range. It is further i302i44 i-~K-2 desiral~le to control the au~er so that it does not feed asphalt when the detected top surface of 'the asphalt-is closer ~han about 16.15 inches from the transducer, to control- the auc3er at its full speed when the distance ~etween the top of the asphalt and the transducer is about 18.15 inches or ~reater, and to have proportionately intermediate speeds or detected levels of the top of the asphalt within this range of a'oout 2 inches. The voltac3e across the capacitor 9~, which is passed to the inte~rater 95, then must be zero if an echo signal occurs indicatinc3 a distance less than 16.15 inches, and ,~ust have a maxi:num value at the ti.~e correspon~ing to a distance of about 18.15 inches or ~reater. ~ccordincJly, the charcJing resistor 91 and the capacitor 9~ are selected to have an RC value permitting this char~3inc3 rate.
ReferrincJ aCJain to E'IG. 6, the receive output of the transducer 82 is normally high, and goes low upon the receipt of an ecno siynal, to reset the flip flop 83. Irhe resultant hi~h level at the output ~5 of the flip flop 83 ~loc~s the ~IOR
3ate 87 to stop countinc3 in the counter, resets the counter, and renders the transistor 96 conductive to ~ass the charge of the charcJing capacitor 90 to the intecJrator 95.
The generation of a ramn is controlled by the transistor 93, which, as indicated, occurs in response to - 1~3 -1302~4 ~ 2~4 positive levels of the divide ~y the 8th and 9th powers of two of the clock signal. ~s apparent in FIG. 7, the second occurrence of this coincidence occurs at a time corresponding to a spacing of 16.15 inches, and hence the transistor 93 is rendered conductive at this time to enable the charging of the capacitor 90. The flip flop 8~ is employed in order to bloc~
charging of the capacitor at the first occurrence of this coincidence, and during the transmit pulse, by holding the capacitor at lo~ level by way of the diode 98 at the output of the flip flop 84. Thus, tne capacitor voltage 90 cannot rise from the time that the flip flop 84 is set by the transmit pulse, until the time that the divide by the eighth power of two signal goes low when the divide by 2 to the 10th power signal is low (at about 1.6 milliseconds from the start of the transmit pulse).
The minimum time at which the system can respond to a receive or echo pulse is deterrnined by the transducer itsel~, and corresponds to about ~.G milliseconds (about 4 to 5 inches). An echo pulse received anytime subsequent to this time results in the resetting of the flip flop 83, tne stop~ing of the counter, the resetting of the counter and the passing of the charge on the capacitor 50 to the integrator 9S
as discussed.
-- lg --1~02i44 o~
subst~nti~lly its full ch~rging v~lue in ,~ tin,e period corresponding to ~bout 2 inches of sp.lce.
While, in 4ccord~nce with the invention, the r.~n,p nl~Y
constitute . continuous ch~rging of the c~p.~citor 90, it is preferred th4t the c~p~citor be ch~rged in steps, to:h.~ve :
pl~te~u intern,edi4te the steps, 4s illustr.lted by the r~n,p 100 in the 9th line of FIG. 7. Thus, .~s illustr4ted in FI~. 6, the ch~rging volt4ge the c4p4citor is the divide by the 4th power of two output of the col~nter. This results in the ch4rging of the c~p,~citor in 4bout 4 steps, e.~ch corresponding to ~bout one qu.~rter of the full height of the r~nlp.
In Q preferred enlbodin,ent of the invention, it is desir4ble to be 4ble to re.~dily ch.~nge the tin~e of initi.~tion of the r~n,p, in order to en4ble either control of the top of the .~sph~lt lt .~ different level, or its sin,ple .~pplic.~tion of the tr4nsducer to different types of equipn,ent. for this purpose, the g~te of the tr.~nsistor ~3 is held low by w~y of the diode 110 ~nd resistor 111 by the closing of 4 selection switch 112. The g~te of the tr.~nsistor ~4 is energi~ed by the divide by the 10th pow~r of two output of the counter, whereby the tr4nsistor ~4 is rendered conductive initi411Y 4t 4 tin,e corresponding to .l sp.~cing fron~ the tr-lnsducer of 21.42 inches, providing the r~n~p 1~0, ~s illustr~ted in the l~st 13021A4 ~ ~o~
line of FIG. 7.
The integr~ter 95 is con,prised of ~ convention~l integr-~ted circuit h~ving circuit-component6.en-~bling -the.;... :.
integr~ion of input sign~ls for .~ peri.od of ~bout 1 second,.
corres~onding to .~bout:10 cYcles of:the ultr~son~ic systenl~-the output of the integr~ter 9S is-~pp.lied to ~ tr~n~istor.
power ~mplifier 116 supplied by ~ const-~nt current source 117 of convention~l construction. The tr~nsistor ~n~plifier 116 is provided with ~ p-~r-~llel ~C feedb.~c~ networ~ 118 to provide f~st response slow dec-~Y ch~r~cteristics, .~nd ~ diode 120 m4y be connected in series with the collector resistor for spi~ed protection. The outpllt of the ~n~plifier 116 is directed to the servo v~lve 130, of convention~l construction. for control of the .~uger nlotor 131.
The devices en~ployed in the circuit of FIG. 6 ~re convention~ nd it n~.~y be convention~l CMOS devices. The tr~nsistors enlployed in the timing control.circuitrY nl.~y constitute convention~l tr~nsnlission gl~tesr ~nd the counter 86 ~nd divider 81 4re convention~l CMOS devices.
The c.~p.~citor ~0 i5 disch.~rged everY cycle of the ultr~sonic pulse, when no echo is received within r~nge of interest, by the divide by the 11th power of 2 sign~l, bY the tr~nsistor 97.
i3~2~44 ~-204 While it is preferred th~t the tr.lnsducer be ~n ultrQsonic trqnsducer for ~pplic.~tions where high he~t c-ln be expected in the n,~teri~l to be distr.ibuted, such ~5 ~sph~lt p.~ving m.lteri41s, it is .~pp.~rent th~t the concept of:the -i*~ention is ~lso qpplic~ble to other~tr~ns-d~cer dë~ices, such ~s pie~o electric devices. Further, in ~ccord~nce-with the invention, it i5 ~pp~rent thqt other dist~nce me~suring ~rr~ngements m~y be employed, such.-~s tri~ngul-~tion devices employing v.~rious forn,s of r~di.~tion. It is still further ~pp.lrent th-lt me.~ns .lre prefer~bly provided for overriding the qutom~tic control of the invention for m~nu~l oper.~tion. in the event thqt ~utom.~tic'control is not desired. This m.~y be effected by conventional devices, for e~.~mple, upon the dis~blement of the circuit of the invention. It is of course further ~pp~rent th~t the output of the circuit c4n be en,ployed, inste.~d of or in .~ddition to ~utom~tic~llY
controlling the ~uger 4nd/or conveYor feed, to control ~n indic~tor~ wherebY ~n oper~tor n,~y view such indic~tor to effect the m~nu~l control of the feed.
~ n electronic tr~nsducer of the ~bove disclosed tYpe provides the .~dv.lnt.~ge of subst.~nti.~l inlm'nity to e~ttern~l influences, since the tr4nsducer is direction.~l. The immunity is incre-~sed bY inhibiting ~ny response to sign~ls received ` 1302i44 ~ 04 fron~ dist.~nces gre~ter th~t 4bout 40 inches. The device i5 hence subst.~nti.~llY in,n.une to control by humps or ridges in .
the:surf~ce being p~ved, n,~teri~l spilled from-the:truc~.or hopper, or n,.~teri.~l pulled in bY n~rrowing of the p~ving-width.~ The tr~nsducer n.~y be mounted ~t-~ loc~tion wher.e it :-does not interfere with inst~ tion or remov~l o~ con,ponents of the p~ving m~chine. The circuit of the invention is .~lso re~dily ~d~ptc~ble to .~uton~tic or remote control of n~.lteri.~l feed.
. It is q further adv~nt~geous fe.~ture of the invention th~t the .~uger or other feed device controlled bY the sYsten is turned off when the first echo received corresponds.to Q
dist.~nce of .~bout 16 inches or less, corresponding to .~n over supply of .~sph~lt . This fe~ture thereby renders the sYsten, oper.~tive to shut off the ~uger in the event of other ob.jects between the luger ~nd the tr~nsducer~ .~nd c.~n prevent in.jury to oper.~ting personnel if theY .~re intention-~llY or ~ccident~lly present in this sp~ce, by effecting the turning off of the ~uger.
While the invention h-~s been disclosed ~nd described with reference to .~ linlitecl nun~ber of en,bodin,ents, it is 1pp-~rent th~t v.~ri.ltions .~nd n,odific.~tions n~y be nl.~de therein, .~nd it is therefore intended in the following cl~ims ~30214A
~ 04 to cover el~ch such vllri,~tion ,lnd modific~tion ~s follows within the spirit qnd scope of the invention.
: . .
Claims (20)
1. In a bulk material conveying equipment having first conveying device for distributing a bulk material in a first direction, a second conveying device for conveying said bulk material in a second direction to said first conveying device, sensing means for sensing the height of said bulk material distributed by said first conveying material, at a given position, for producing a control signal, and means responsive to said control signal for controlling the quantity of bulk material distributed by said first conveying device to slid given position for maintaining said height substantially constant the improvement wherein said sensing means comprises non-contacting sensing means fixedly mountedly on said equipment spaced from said bulk material for producing said control signal, whereby said control signal is a function of the distance between said non-contacting sensing means and an upper surface of said bulk material at said given position.
Th er
Th er
2. The bulk material conveying equipment of claim wherein said first direction is a horiaontal direction, said second direction is horizontal direction transverse to said first direction, and said non-contacting sensing means comprises means for transmitting a beam of radiation to and receiving radiation reflected from said upper surface and control means including means responsive to received radiation for producing said control signal.
3. The bulk material conveying equipment of claim 2 wherein said means for transmitting and receiving comprises an ultrasonic transducer.
4. The bulk material conveying equipment of claim 3 wherein said equipment comprises a paving device adapted to be movable along a first surface in the direction opposite said second direction for distributing and compacting paving material on said first surface, said first conveying device comprises a horizontal rotatable auger, said paving device further having a floating screed mounted rearwardly of said auger, and said transducer is mounted on said paving device, said given position being forwardly of said auger at the axial outer extremity thereof.
5. The bulk material conveying equipment of claim 4 wherein said control means further comprises a source of clock pulses, means responsive to said clock pulses for periodically controlling said sensing means to transmit a pulse of ultrasound, counter means for producing outputs corresponding to a plurality of different divisions of said clock pulses, first gate means responsive to the transmission of a pulse of ultrasound by said sensing means for enabling said divider means to count clock pulses and responsive to reception of a subsequent echo pulse for stopping and resetting said divider means, ramp generator means responsive to the count of said counter means for producing a ramp signal of an amplitude that is a function of the distance between said transducer and bulk material at said given position, and means responsive to said ramp signal for producing said control signal.
6. The bulk material conveying equipment of claim 5 wherein said means, and second gate means responsive to the integrating means, and second gate means responsive to the reception of an echo signal for applying said ramp signal to said integrating means.
7. The bulk material conveying equipment of claim 5 further comprising means responsive to the absence of reception of echo signal within a given time following the transmission of an ultrasound pulse for resetting said counter means
8. The bulk material conveying equipment of claim 5 wherein said ramp generator means comprises a capacitor, and means charging said capacitor with a first determined output of said counter, and said control means further comprises means responsive to a second determined output of said counter means for periodically discharging said capacitor.
9. The bulk material conveying equipment of claim 8 wherein said control means comprises means responsive to further outputs of said counter means for inhibiting charging of said capacitor for a determined time during and following the transmission of an ultrasound pulse.
10. The bulk material conveying equipment of claim 9 wherein said control means further comprises means for selectively varying said determined time during which said capacitor is inhibited from charging.
11. In a road paving equipment movable along a first surface on which paving material is to be deposited and compacted, and comprising an auger for distributing paving material in a first direction transverse of the direction of movement of the equipment, a conveying device for conveying said paving material to said auger in a direction opposite said direction of movement, a screed mounted rearwardly of said auger, sensing means mounted on said equipment for producing a control signal that is a function of the height of said paving material at a given position adjacent said auger, and means responsive to said control signal for controlling the distribution of said paving material to said given position for maintaining said height substantially constant;
the improvement wherein said sensing means comprises non-contacting sensing means fixedly mounted on said equipment spaced from said paving material at said given position for producing said control signal, whereby said control signal is a function of the distance between said non-contacting sensing means and an upper surface of said paving material at said given position.
? cin BK-204
the improvement wherein said sensing means comprises non-contacting sensing means fixedly mounted on said equipment spaced from said paving material at said given position for producing said control signal, whereby said control signal is a function of the distance between said non-contacting sensing means and an upper surface of said paving material at said given position.
? cin BK-204
12. The road paving equipment of claim 11 wherein said sensing means comprises a control circuit, means for periodically producing a ramp signal having a duration that is a function of said distance, and integrating circuit means for producing said control signal, and gate means for passing the instantaneous level of said ramp signal to said integrating circuit in response to the sensing by said sensing means of said paying material.
13. The road paving equipment of claim 12 wherein said sensing means further comprises an ultrasonic transducer for transmitting ultrasonic pulses and receiving ultrasonic echoes, said control circuit further comprising timing circuit means for periodically energizing said transducer to transmit ultrasonic pulses, said timing circuit means further comprising means initiating the generation of a ramp signal a first determined time following the transmission of an ultrasonic pulse, means for stopping the genereation of said ramp signal at a second predetermined time following said first time, and ameans for suppressing said ramp signal at a third predetermined time following its generation.
14. The road paving equipment of claim 13 wherein said timing circuit means further comprises means for adjust-ing the time of occurrence of said second predetermined time.
15. A control circuit for producing a control signal in response to the output of an ultrasonic transducer wherein the transducer is responsive to an input signal for transmitting an ultrasonic pulse and is responsive to an ultrasonic echo for outputting an echo signal, said control circuit comprising a timing circuit having a first output for periodically controlling said transducer to transmit ultrasonic pulses, a ramp generation circuit for generating a ramp signal an integration circuit for producing said control signal, first gate for passing the instantaneous amplitude of said ramp signal to said integration circuit, and means responsive to said echo signal for energizing said first gate circuit to pass the amplitude of said ramp signal to said integration circuit. said timing circuit further comprising means initiating the generation of said ramp signal at a second predetermined time following said first predetermined time, means stopping the generation of said ramp signal at a third predetermined time following said second predetermined time, and means for suppressing said ramp signal at a fourth predetermined time following said second predetermined time.
16. The control circuit of claim 15 wherein said timing circuit comprises a clock signal generator and a counter, said counter having a plurality of outputs corresponding to different divisions of the clock signal, and said ramp generator comprises a capacitor and a charging circuit for the capacitor, said means supressing said ramp signal comprising means responsive to a given output of said counter for discharging said capacitor.
17. The control circuit of claim 16 wherein said control circuit further comprises flip flop means responsive to the transmission of ultrasonic pulses for enabling said counter to count and responsive to the reception of a echo pulse for resetting said counter and enabling said first gate circuit to pass the amplitude of said ramp signal to said interfration circuit.
18. The control circuit of claim 16 wherein said timing circuit further comprises second gate circuit responsive to determined outputs of said counter for enabling the charging of said capacitor at said second predetermined time.
19. The control circuit of claim 18 further comprising switch means enabling the control of the outputs of said counter which are employed to determine said second predetermined time.
20. The control circuit of claim 16 wherein a determined output of said counter is employed to charge said capacitor, whereby said capacitor is stepwise charged.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000591074A CA1302144C (en) | 1989-02-15 | 1989-02-15 | Material control arrangement for bulk of materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000591074A CA1302144C (en) | 1989-02-15 | 1989-02-15 | Material control arrangement for bulk of materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1302144C true CA1302144C (en) | 1992-06-02 |
Family
ID=4139626
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000591074A Expired - Fee Related CA1302144C (en) | 1989-02-15 | 1989-02-15 | Material control arrangement for bulk of materials |
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| Country | Link |
|---|---|
| CA (1) | CA1302144C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102704378A (en) * | 2012-05-24 | 2012-10-03 | 三一重工股份有限公司 | Spreading machine, and method and device for controlling material level of spreading machine |
| US8979423B2 (en) | 2012-10-10 | 2015-03-17 | Caterpillar Paving Products Inc. | Automatic material height sensor for asphalt pavers |
-
1989
- 1989-02-15 CA CA000591074A patent/CA1302144C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102704378A (en) * | 2012-05-24 | 2012-10-03 | 三一重工股份有限公司 | Spreading machine, and method and device for controlling material level of spreading machine |
| CN102704378B (en) * | 2012-05-24 | 2015-04-22 | 三一重工股份有限公司 | Spreading machine, and method and device for controlling material level of spreading machine |
| US8979423B2 (en) | 2012-10-10 | 2015-03-17 | Caterpillar Paving Products Inc. | Automatic material height sensor for asphalt pavers |
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