GB2075373A - Applying additive to tobacco - Google Patents

Abstract

An apparatus which sprays atomized water, casing, plasticizer or another liquid additive onto a stream or tow of tobacco or filter material has one or more single-material atomizing nozzles (11) which receive additive from a pump (16) by way of a first conduit (13) which contains a check valve (22) between the pump and the junction (13a) with the discharge end of a second conduit (19) serving to supply compressed air when the pressure of additive does not suffice to ensure a reliable atomizing action. The second conduit (19) is connected to a source (23) of compressed air and contains a check valve (21) which is closed by additive when the latter is maintained at normal pressure. When the pressure of additive drops, such as immediately after starting or on stoppage of the pump, compressed air opens the check valve in the second conduit (19), closes the check valve (22) in the first conduit (13) and expels the additive from the first conduit (13) into the nozzle or nozzles (11) at a pressure which suffices to ensure a satisfactory atomizing action. <IMAGE>

Description

SPECIFICATION Apparatus for contacting tobacco or the like with an atomized additive The present invention relates to apparatus for treating tobacco or other materials which are used in the manufacture of smokers' products. More par ticulary, the invention relates to improvements in apparatus for contacting tobacco, filter material or the like with atomized additives in the form of minute droplets of water, casing, plasticizer or the like. Still more particularly, the invention relates to improvements in apparatus wherein the atomizing means preferably (but not necessarily) includes one or more noules which spray minute droplets of additive onto a moving body of tobacco, filter mater ialorthelike.

It is well known to subject tobacco and/or filter material to a variety of treatments some of which involve contacting the material to be treated with a finely comminuted liquid or liquefied additive. For example, it is well known to employ spray noules which sprinkle droplets of water onto a stream of tobacco particles to thereby influence the moisture content of tobacco in a machine which conditions tobacco ahead of a cigarette maker or the like. It is also known to contact particles of tobacco with a suitable flavoring agent (e.g., casing) which is sprayed onto a stream of tobacco particles and serves to enhance the aroma and/or other charac teristics of tobacco. Casing can be admitted to tobacco leaves, to tobacco shreds orto otherwise configurated fragments or particles of tobacco.

Furthermore, it is well known to spray atomized plas ticizer (such as triacetin) onto a towoffilamentary filter material which is about to be converted into a filter rod. The plasticizer causes adjacent portions of neighbouring filaments to adhere to each other and to thus form a myriad of paths for the flow of tobacco smoke through the filter mouthpiece of a filter cigarette, cigar or cigarillo. This ensures that the filter mouthpiece can intercept a substantial per centage of nicotine, condensate and/or other unde sirable constituents of tobacco smoke.

In many presently known apparatus for the appli cation of atomized liquid or liquefied additives to tobacco, filter material or the like, the nozzle or noz zles which spray the additve onto the material to be contacted thereby are so-called two-material noz zles. This term is intended to denote nozzles which receive additive by way of a conduit wherein the additive is advanced by a gaseous propellant or car rier medium. Thus, atomizing is effected under the influence of a medium other than the additive, and the pressure of such medium must be sufficient high to ensure a satisfactory or acceptable atomizing action. Two-material nozzles operate satisfactorily, insofar as the atomizing action is concerned. How ever, they exhibit a number of drawbacks, such as the side effects of gaseous propellant upon the area surrounding the nozzle or nozzles.For example, gaseous propellant which issues from the nozzle or nozzles caused the atomized additive to form a per manent fog or could whose particles deposit on adj acent portions of the machine and constitute or cause accumulations of undesirable foreign matter which must be cleaned at relatively frequent intervals with attendant costs for the work involved as well as owing to stoppage of the machine for the purpose of cleaning. If the gaseous propellant is used to atomize casing which is about to contact particles of tobacco, the gas is likely to cool the casing so that the atomized liquid is less likely to penetrate into orto otherwise satisfactorily contact or influence the particles of tobacco.Still further, at least some of the gaseous propellant must be gathered after it issues from the atomizing nozzle or nozzles, and such gathering necessitates the provision of additional equipment which occupies space in the very region where the space is at a premium and whose operation entails the consumption of substantial amounts of energy.

In view of the above-outlined and other drawbacks of multi-material atomizing nozzles, many presently known atomizing apparatus which serve to apply atomized additives to tobacco, filter material or the like utilize so-called single-material nozzles, i.e., nozzles which are not connected with a source of gaseous propellant. This means that the pressure of supplied additive must suffice to ensure satisfactory atomizing action before the additive contacts the particles of tobacco, the filaments of a filter material or the like.Thought a single-material nozzle does not exhibit all of the drawbacks which are inherent in the utilization of a two-material nozzle, singlematerial noules of presently known design (or more accurately stated, apparatus which are presently used to atomize additives for tobacco or the like and employ single-material atomizing nozzles) still exhibit a host of serious drawbacks which affect the quality of treated material and can cause longlasting interruptions in operation of the machine or machines in which such apparatus are put to use.

A well known and serious drawback of presently known apparatus which utilize single-material atomizing nozzles is that the pressure of additive which is to be atomized does not invariably suffice to ensure full atomizing of each and every batch or increment of additive which is supplied to the noule.

Thus, if the pressure of additive drops below a given value, the atomizing action of the nozzle is affected practically without any delay so that the nozzle discharges streamlets or larger drops instead of minute droplets or globules of finely atomized liquid. Such situation is likely to arise immediately after the conduit which connects the noule with a sourceofaddi- tive begins to admit additive to the nozzle, i.e., during that stage of operation of the atomizing apparatus when the pressure of additive in the conduit must be built up to a value at which the pressure of the additve suffices to guarantee a satisfactory atomizing action. During the initial stage of admission of additive, the nozzle begins to drip.The dripping stage is followed by an interval during which the nozzle discharges streamlets of non-atomized additive, and such interval is followed by the stage during which the additives is properly atomized. The same situation, but in reverse order of the stages, arises when the nozzle is sealed from the source of additive, i.e., the noule then discharges a number of streams of additive, and such stage is followed by discharge of large individual drops (dripping) before the noule ceases to discharge any additive.

The just described mode of operation of an apparatus with one or more single-material nozzles is especially unsatisfactory when the apparatus is used for wetting of tobacco particles. For example, the apparatus will discharge excessive quantities of water per unit length of a tobacco stream when the noule or noules are disconnected from the source of additive.The streams of water which are discharged onto the particles of tobacco are followed by large droplets so that the trailing end of the stream of tobacco particles is thoroughly soaked to form batches of sludge which remain in the path of the tobacco stream and cause problems when the apparatus is restarted because they interfere with proper transport of fresh tobacco past the atomizing nozzle or noules. Moreover, the sludge is likelyto adversely affect the quality of freshly admitted tobacco particles by binding the oncoming particles and by excessively increasing their moisture content.

The invention resides in the provision of an apparatus for contacting tobacco particles, filter material orthe like with an atomizable additive, such as water, casing or plasticizer. The apparatus comprises at least one atomizing element (such as an atomizing nozzle, preferably a single-material atomizing nozzle), a tank or another suitable source of additive, first conduit means connecting the source of additive with the atomizing element, a pump (e.g., a gear pump and a variable-speed motor which drives the pump) or analogous means for conveying additive from the source to the element at a variable pressure, a source of pressurized fluid (e.g., a source of compressed air), second conduit means connecting the source of pressurized fluid with the first conduit means at a junction located between the atomizing element and the conveying means, and pressure-responsive means (preferably a suitable check valve or one-way valve) provided in the second conduit means and operative to admit pressurized fluid into the first conduit means in response to a drop of pressure of additive in the first conduit means below a preselected value, namely, a value at which the pressure of additive alone does not suffice to ensure adequate atomizing of additive at the atomizing element or elements.

The apparatus preferably further comprises blocking means (preferably a second check valve) provided in the first conduit means between the junction of the first and second conduit means and the conveying means to prevent the flow of pressurized fluid all the way to the conveying means orto the source of additive when the pressure-responsive means in the second conduit means admits pressurized fluid into the first conduit means.The blocking means is designed to prevent the flow of pressurized fluid to the conveying means and/orto the source of additive irrespective ofthe pressure of pressurized fluid in the first conduit means downstream of the blocking means but permits the additive to flow from the conveying means toward and beyond the junction (i.e., to the atomizing element or elements) when the pressure of additive in the first conduit means exceeds the pressure of pressurized fluid.

The apparatus can further comprise pressure regulating means (e.g., a suitable adjustable pressure regulating valve) which is provided in the second conduit means upstream of the pressure-responsive means and is operative to maintain the pressure of pressurized fluid at the respective side of the pressure-responsive means below the aforementioned preselected value. This ensures that the prnssurernsponsive means admits pressurized fluid into the first conduit means only and alone when the pressure of additive in the first conduit means is below the preselected value, i.e., when the pressure of additive in the first conduit means does not suffice to enzure adequate atomizing of additive which reaches the atomizing element.

The apparatus preferably further comprises shutoff valve means (e.g., a manually operated shutpff valve, a solenoid-operated shutoff valve or the like) which is installed in the second conduit means and seals the source of pressurized fluid from the junction between the first and second conduit means when the apparatus is not in use.

The apparatus can further comprise or can be associated with suitable means for transporting tobacco, filter material or the like past the atomizing element or elements. Such transporting means may comprise a rotary conveyor (e.g., forthe application of casing to tobacco particles), a vibratory conveyor (e.g., for wetting tobacco particles by atomized water), or at least one pair of advancing rolls (which can transport a tow of filamentary filter material past the atomizing element or elements).

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following description of certain specific embodiments with reference to the accompanying drawing.

FIG. 1 is a schematic partly elevational and partly sectional view of a tobacco conditioning machine which cooperates with or incorporates a novel apparatus for contacting the particles of tobacco with an atomized additive, such as casing; FIG. 2 is a fragmentary schematic elevational view of a filter rod making machine which cooperates with or incorporates an apparatus for contactingthe filaments of filter material with atomized plasticizer; and FIG. 3 is a fragmentary schematic partly eleva; tional and party sectional view of a machine which servesfor the heating of tobacco and cooperates with or incorporates a novel apparatus for contacting the particles of tobacco with atomized water.

Referring first to FIG. 1, the reference character 1 denotes a composite transporting unit which comprises an upwardly sloping carded endless belt conveyor 2 cooperating with rotary refuser paddle wheels 3 to advance a continuous stream S of tobacco particles in the direction of the arrow A. The blades or vanes of the paddle wheels 3 perform the function of rudimentary equalizing devices by retain ing the surplus of tobacco particles (e.g., shreds) which are fed onto the lower end portion of the upper reach of the conveyor 2. The latter may constitute a mobile side wall of a magazine for a relatively large supply of tobacco particles or it may receive a non-equalized stream of tobacco particles from a further conveyor, not shown.The upper end turn of the conveyor 2 delivers successive increments of the equalized or substantially equalized stream S onto the upper reach of a second belt conveyor 4 cooperating with a suitable weighing device 6 which monitors the weight of successive increments of the stream S and transmits signals (via conductor means 6a) to a varible-speed prime mover (not shown) for the pulley or pulleys of the conveyor 4.

The provision of weighing device 6 ensures that each increment or unit length of the stream S leaving the conveyor4 contains a predetermined quantity of tobacco particles. The thus finally equalized stream S is discharged onto the upper reach of a further belt conveyor7 which admits the stream S into the inlet of a hollow rotary drum-shaped treating or processing conveyor 8. The conveyor 8 comprises a cylin drical shell 8a whose axis slopes downwardly, as considered in the direction of advancement of tobacco particles therethrough, and the inner side of which is provided with longitudinally extending agitating or lifting elements 8b in the form of vanes of coils.As the shell 8a rotates, the agitating elements 8b repeatedly lift and dump sections of the stream S to ensure that each and every particle or fragment of tobacco is subjected to identical treat ment, e.g., to the drying action of steam which is circulated through the elements 8b if such elements constitute coils. Treated tobacco particles are discharged onto the upper reach of an endless take-off belt conveyor 18 which transports the treated material to a further processing station, e.g., to the magazine of a cigarette rod making machine, such as a machine known as Garant or SE 80 produced and sold by the assignee of the present application.

The shell 8a of the treating conveyor 8 is rotated by a main prime mover 9 (e.g., a variable-speed electric motor) through the medium of a transmission 9a which drives a ring gear 8c at the exterior of the shell 8a. The transmission 9a further transmits motion (see the connection 18a) to the left-hand pulley or pulleys for the take-off conveyor 18. Additional motion transmitting connections (not specifically shown) between the motor9 and/or transmission 9a on the one hand and the conveyors 2 and 7 of the transporting unit 1 on the other hand serve to drive the conveyors of the transporting unit in synchron ism with the angular velocity of the shell 8a. The direction in which the particles of tobacco advance from the upper reach of the carded conveyor 2 onto the take-off conveyor 18 is indicated by arrows.

The heretofore described parts of the tobacco pro cessing machine shown in FIG. 1 are known. Refer ence may be had to commonly owned U.S. Pats.

Nos. 3,372,488,3,429,317, 3,760,816 and 3,590,826 which describe and show similar or analogous machines. The disclosures of such patents are incorporated herein by reference.

The apparatus 12 which embodies the present invention comprises at least one atomizing element here shown as a nozzle 11 which is installed in the interior of the shell 8a close to the discharge end of the treating conveyor 8 and serves to spray onto successive increments of the stream S a suitable additive, e.g., a casing which may constitute a flavoring or aroma-enhancing agent of any known composition. The casing is a flowable substance which may be and normally is a liquid or paste. The nozzle 11 which is shown in FIG. 1 is a single-material nozzle, i.e., the material which issues therefrom is atomized (at least under normal circumstances) under its own pressure and owing to the design of the nozzle ratherthan underthe action of a gaseous propellant.

As shown in FIG. 1, the nozzle 11 is installed in or close to a portion of the path for tobacco particles of the stream S wherein the particles trickle downwardly by gravity so that they are loose and each thereof can be contacted, from all sides, by atomized additive which is supplied to the nozzle 11 by a first oradmixing conduit 13. The latter receives additive from a feeding device 14 including a tank, reservoir or analogous source 17, and a conveying pump 16 which is installed in the conduit 13 and serves to draw the additive from the tank 17. The pump 16 is driven by a variable-speed motor 16a whose speed is synchronized with that of the main prime mover 9.

The apparatus 12 further comprises a second conduit 19 which serves to admit into an intermediate portion of the first conduit 13 a compressed gaseous fluid (e.g., compressed air) during certain stages of operation of the machine shown in FIG. 1. The compressed-gas conduit 19 contains a spring-biased pressure-responsive check valve or one-way valve 21 whose spherical or otherwise configurated valving element 21 b normally prevents the admission of compressed gas into the conduit 13. A blocking means here shown as a second spring-biased check valve 22 is installed in the conduit 13 upstream of the junction 13a between the conduits 13 and 19, i.e., between such junction and the additive-conveying pump 16. The intake end of the conduit 19 is connected to a source 23 of pressurized gaseous fluid, e.g., a suitable air compressor of any known design.

The conduit 19furthercontains a shutoff valve 24 (e.g., a conventional solenoid-operated valve) and a preferably adjustable pressure regulating valve 26.

The valves 24,26 are installed in the conduit 19 intermediate the source 23 and check valve 21, and the valve 26 is located downstream of the valve 24.

The adjustment or setting of the pressure regulating valve 26 is normally such that the pressure of gaseous fluid acting against the valving element 21 b of the check valve 21 is lower than the pressure of liquid or liquefied additive in the conduit 13. For example, if the pressure of additive in the conduit 13 is 2 bar, the pressure of gaseous fluid acting on the valving element 21 b of the check valve 21 is at least slightly less, e.g., in the range of 1.5 bar.

The operation of the apparatus 12 is as follows: When the machine including the transporting unit 1 and treating conveyor 8 is started and the leader of the stream S reaches the right-hand end portion of the shell 8a, i.e., when the particles of tobacco begin to descend in the region of the atomizing nozzle 11, the apparatus 12 is started, either by hand or automatically, e.g., by resorting to a monitoring device which starts the motor 1 6a for the pump 16 when it detects particles of tobacco in a predetermined portion of the path extending from the upper reach of the carded conveyor 2 to the upper reach of the take-off conveyor 18. The pump 16draws additive from the tank 17 and advances it in the conduit 13 toward the nozzle 11.During such initial stage of operation of the apparatus 12, the pressure of additive in the conduit 13 is lower than the pressure of gaseous fluid in the conduit 19; therefore, compressed gas which is supplied by the source 23 and passes through the pressure regulating valve 26 (the shutoff valve 24 is opened simultaneously with or shortly after starting of the motor 16a) opens the check valve 21 and flows into the conduit 13. The gaseous fluid which issues from the conduit 19 flows toward the nozzle 11 as well as toward the check valve 22 which is thereby held in closed position.

This enables the additive in the conduit 13 upstream of the check valve 22 to build up a pressure which rises toward and soon exceeds the pressure of gaseous fluid issuing from the conduit 19. The first or foremost portion of additive which has passed through the freshly opened check valve 22 is entrained by the gaseous fluid toward and is totally atomized during escape from the nozzle 11 so that the particles of to bacco are contacted by properly atomized additive as soon as such additive begins to issue from the nozzle 11. The pressure of additive in the conduit 13 continues to rise and causes the additive to close the check valve 21 so as to terminate the admission of compressed gaseous fluid into the conduit 13.From then on, the pressure of additive (such pressure is established and maintained by the pump 16) suffices to ensure adequate atomization of additive which issues from the nozzle 11.

When the apparatus is arrested in response to termination or interruption of transport of tobacco particles along the path extending from the conveyor 2 to the conveyor 18, the shutoff valve 24 remains open for a certain interval of time after stoppage of the motor 1 6a for the pump 16. Consequently, the pressure of additive in the conduit 13 drops but the pressure of gaseous fluid in the conduit 19 remains unchanged. Therefore, the gaseous fluid opens the check valve 21 to penetrate into the conduit 13 at the junction 1 3a and to ensure adequate atomizing of any and all remnants of additive which have advanced in the conduit 13 beyond the check valve 22.The gaseous fluid which has penetrated into the conduit 13 automatically closes the checkvalve 22 subsequent to opening of the check valve 21 and invariably expels from the conduit 13 (downstream of the check valve 22) any and all traces of additive which is completely atomized by the nozzle 11 prior to contacting the trailing end of the stream S which has advanced through the interior of the major part of the shell 8a on its way toward the take-off conveyor 18.

The shutoff valve 24 constitutes an optional but desirable and advantageous feature of the apparatus 12. This valve ensures that compressed gaseous fluid which is supplied by the source 23 cannot escape via nozzle 11 when the apparatus 12 is idle.

The valve 24 can be opened or closed by hand or by a suitable automatic remote-control actuating system which opens the valve 24 on starting of the motor 9 (either simultaneously or with a selected delay) and closes the valve 24 on stoppage of the motor 9, preferably with a slight delay following stoppage of the motor 16a so as to ensure that com- pressed gaseous fluid which enters the conduit 13 on opening of the check valve 21 can close the check valve 22 and expel all remnants of additive from the conduit 13 before the valve 24 is closed.

The shutoff valve 24 can be used as a substitute for the check valve 21 in the conduit 19. If the check valve 21 is omitted, the apparatus 12 is preferably provided with suitable actuating means which automatically opens the shutoff valve 24 in response to a predetermined change of pressure in the conduit 13, i.e., in response to starting ofthe motor 16a for the pump 16. The arrangement which is shown in Fig. 1 is preferred at this time because it is simpler since the shutoff valve 24 can be manipulated by hand.Also, were the check valve 21 omitted, it would be necessary (at least under certain circumstances) to provide in the conduit 13 a discrete pressure monitoring device and to utilize the valve 24 or an equivalent valve to regulate the admission of compression gaseous fluid from the source 23 into the conduit 13 in response to signals from the discrete pressure monitoring device.

The check valve 22 is desirable and advantageous because it ensures that full pressure of gaseous fluid issuing from the conduit 19 during a buildup of the pressure of additive is used for atomization of additive which has been permitted to enter the conduit 13 downstream of the check valve 22 prior to closing of such valve by gaseous fluid which enters the conduit 13 on opening of the check valve 21. The setting of check valve 22 is such that it opens when the pressure of additive upstream of the valve 22 exceeds the pressure of gaseous fluid in the conduit 19 downstream of the pressure regulating valve 26.If desired, the check valve 22 can be replaced by a shutoff valve which closes in response to opening of the check valve 21; however, the apparatus 12 of FIG. 1 is preferred at the present time owing to its simplicity and the ability of valve 22 to close in automatic response to admission of gaseous fluid into the conduit 13 on opening of the check valve 21.

An important advantage of the apparatus 12 is-4hat it renders it possible to utilize a single-material atomizing nozzle 11 because, under normal operation conditions, additive which is supplied by the pump 16 is atomized solely under the action of pressure which is generated by the pump 16. Compressed gaseous fluid which is supplied by the source 23 can enterthe conduit 13 only during certain stages of operation of the apparatus 12, namely, when the pressure of additive in the conduit 13 is lower than the pressure of gaseous fluid in the conduit 19 upstream of the check valve 24.This ensures that the gaseous fluid can penetrate into the conduit 13 to close the check valve 22 and to effect adequate atomizing of additive when the latter is supplied in relatively small quantities, i.e., during starting of the apparatus 12 or after the apparatus 12 is turned off but the conduit 13 still contains or receives some additive downstream of the check valve 22. It goes without saying that the source 23 can supply a gaseous fluid other than air, e.g., steam, nitrogen and/or others. The check valve 21 is or can be sufficiently sensitive to immediately react to a requisite drop of pressure of additive in the conduit 13, i.e., to open as soon as the pressure differential at the opposite sides of its valving element 21 b suffices to overcome the resistance of the spring 21a which normally maintains the valving element 21 b in sealing engagement with the seat 21c.

It will be noted that the nozzle 11 acts as a singlematerial nozzle during normal operation of the apparatus 12 but performs the function of a twomaterial nozzle when the apparatus is started or arrested. Thus, gaseous fluid which is supplied by the conduit 19 acts as a propellant for additive (casing) only when the pressure of additive is too low to enable the noule 11 to convert the additive into a fine spray of atomized particles.

FIG. 2 illustrates a machine for the making of a continuous filter rod wherein a continuous tow 131 of filamentary filter material is drawn from a bale 132 (stored in a container 132a) and is draped into a continuous web of cigarette paper or other suitable strip-shaped flexible wrapping material. The machine of FIG. 2 embodies or is combined with an apparatus 112 which is analogous to the apparatus 12 of FIG. 1 and serves to sprinkle atomized additive (namely, a plasticizer, such as triacetin) onto successive increments of the running tow 131 ahead of the location where the tow is converted into a rod-like filler and is draped into the web of wrapping material. All such parts of the apparatus 112 which are identical with or clearly analogous to corresponding parts of the apparatus 12 of FIG. 1 are denoted by similar reference characters plus 100.The nozzle 111 of the apparatus 112 serves to spray atomized plasticizer (additive) from above onto successive increments of the running tow 131 in a region above a collecting vessel 141 serving to gatherthe plasticizer which has penetrated through the tow 131.

The filter rod making machine of FIG. 2 comprises two main sections or units, namely a processing or treating unit 127 which treats the tow 131 prior to conversion of the two into the aforementioned rodlike filler, and a rod-forming unit including a socalled gathering horn 128 (shown in the lower right-hand portion of FIG. 2) which converts the treated tow 131 into a rod-like filler and directs the filler into the wrapping mechanism of the second unit.

The exact details of the two units, save for the treatment of tow 131 by the improved apparatus 112 in the unit 127, form no part of the present invention.

Reference may be had to commonly owned U.S.

Pats. Nos. 4,132,189,3,974,007 and 3,865,016 whose disclosures are incorporated herein by reference.

The unit 127 comprises the aforementioned vessel container 132a for the bale 132 which contains a substantial supply of tow 131. The tow is withdrawn by a first pair of advancing rolls 129 and, on their way toward the nip of the rolls 129, successive increments of the tow 131 pass through a first pneumatic banding device 133 and thereupon through a second pneumatic banding device 134.

These banding device discharge currents of compressed gas across the path of the tow 131 so that the filaments of the tow become separated from each other and the tow is converted into a relatively wide band of neighboring filaments which are accessible for uniform application of atomized plasticizer. The banded tow 131 then advances toward and through the nips of two additional pairs of advancing rolls 136, 137. The rolls 137 are located ahead of the aforementioned gathering horn 128 forming part of the second unit of the filter rod forming apparatus.The filaments of the tow 131 are normally crimped, and the extent of crimping during travel of successive increments of the tow past the atomizing nozzle 111 can be regulated by a variable-speed motor 129a which can regulate the ratio of a variable-speed transmission 1 29b for the lower roll of the pair of rolls 129. A main prime mover 138 (e.g., a variable-speed electric motor) drives the rolls 136, 137 by way of belt or chain transmissions 138a, 138b.Afurther belt or chain transmission 1 38c drives the input element of the transmission 129b. Still another belt or chain transmission 138d transmits motion to mobile parts of the second unit including the horn 128.

That portion of the tow 131 which travels through the plasticizer applying station 139 between the pairs of rolls 136, 137 forms a wide band which is thin or flat so that it preferably comprises a single layer or a small number of layers of filaments. This enables the nozzle 111 to spray atomized plasticizer onto each filament to thus ensure that the filler of the filter rod which is formed in the second unit will exhibit satisfactory characteristics as regards its ability to intercept nicotine, condensate and/or other deleterious ingredients of tobacco smoke.

The aforementioned vessel 141 preferably forms part of a larger housing 141 A which confines the upper side as well as the underside of the tow 131 in the region between the advancing rills 136 and 137.

The housing 141A is provided with internal suction channels 142 which communicate with the inlet of a common evacuating pipe 143 serving to withdraw the surplus of plasticizer and to return it to the source 117 of the feeding device 114. The outlet of the evacuating pipe 143 is connected with a suction generating device 146 (e.g., a fan) by way of a filter or separator 144 serving to segrepate plasticizer from air so that the intercepted plasticizer can flow back into the source 117.

The first or admixing conduit 113 connects the source 117 with the atomizing nozzle 111 and contains a motor-driven pump 116, a preferably adjustable flow restrictor 147 downstream of the pump 116, a pressure gauge 148 downstream of the flow restrictor 147, and the check valve 122 (corresponding to the check valve 22 of the apparatus 12 shown in FIG. which is installed in the conduit 113 upstream of the junction 1 13a between this conduit and the second or compressed-gas conduit 119. The latter receives compressed gaseous fluid (e.g., air) from a source 123, and contains a manually or automatically operable shutoff valve 124, an adjustable pressure regulating valve 127, and a check valve 121 corresponding to the valve 21 of the apparatus 12.

The pump 116 is preferably a gear pump. The same holds true for the pump 16 in the apparatus 12 of FIG. 1.

The motor 138 determines the speed at whch the tow 131 is transported through the conditioning station within the housing 141A. Furthermore, the motor 138 determines the speed of the pump 116 so that the ratio of quantity of atomized plasticizer which is sprayed onto the tow 131 above the vessel 141 to the quantity of filamentary material which has passed through the housing 141A per unit of time remains at least substantially constant.

When the apparatus 112 is turned on, the check valve 121 opens in the same way and for the same purpose as described in connection with the valve 21 of the apparatus 12, i.g, to close the check valve 122 and to ensure full atomization of the initial stream of plasticizer which is supplied by the pump 116. The plasticizer closes the check valve 121 when its pressure rises sufficiently to effect opening of the check valve 122, and the nozzle 111 thereupon atomizes plasticiser whose pressure is established and maintained solely by the pump 116 as a function of the RPM ofthe main prime mover 138.When the apparatus 112 is turned off, the check valve 121 is opened again and the gaseous fluid which penetrates into the conduit 113 closes the check valve 122 and ensures adequate atomizing of the remaining traces of plasticizer in the conduit 113 downstream of the check valve 122.

FIG. 3 illustrates a portion of a machine which serves to change the moisture content and/or temperature of tobacco and cooperate with or embodies an apparatus 212 corresponding to the apparatus 12 or 122. The machine of FIG. 3 includes an elongated upwardly sloping tunnel 249 wherein the particles 259 of tobacco are subjected to an intensive and highly uniform steaming, heating and/or moistening or wetting action. The tunnel 249 surrounds, forms part of or includes a trough-shaped vibratory conveyor 251 which causes the particles of tobacco to form a fluidized stream 261 advancing upwardly from a feeding conveyor 262 (e.g., a suitably inclined chute) toward a take-off conveyor 263 which constitutes a second chute.In the machine of FIG. 3, the tunnel 249 is assembled of a series of ring-shaped pipes 253 which together form a tubular sleeve surrounding the path of tobacco particles 259 on the vibratory conveyor 251. The outer sides of the pipes 253 are surrounded by an insulating jacket 254 which prevents escape of heat into the surrounding atmosphere. The reference characters 256,257 and 258 denotes pipes or conduits which supply steam and/or hot air to the bottom portions ofthe pipes 253. Such bottom portions are formed with orifices in the form of pores, perforations or the like to per mit small currents of treating medium to rise into the interior or the tunnel 249 and to thereby lift the adja cent particles 259 of tobacco.Such lifting action, combined with the agitating action of the conveyor 251, causes the stream of tobacco particles 259 which are admitted by the chute 262 to form the aforementioned fluidized body or stream 261 which advances toward the chute 263. Fluidizing of tobacco particles 259 is highly desirable and advantageous because it breaks up eventual agglomerations of tobacco and ensures that all sides of each particle 259 are fully exposed during contact with atomized additive (e.g.,water) which is supplied by the noule means 211 of the apparatus 212. All such parts of the apparatus 212 which are identical with or clearly analogous to corresponding parts ofthe apparatus 12 are denoted by similar reference characters plus 200.

The left-hand end portion or discharge end of the tunnel 249 is adjacent to a hood 264 which is connected with a suction pipe 266 and serves to evacuate vapors issuing from the bottom portions of the pipes 253. The pipe 266 is connected with a fan, such as the suction generating device 146 of FIG. 2, and contains a flap 266a or another suitable valve which regulates the rate of evacuation of vapors from the interior of the tunnel 249. A water collecting pipe 267 is located at the right-hand end of the conveyor 251; this pipe collects water which happens (at times) to flow counter to the direction of advancement of tobacco particles 259. The variable-speed drive means for the conveyor 251 is shown schematically at 252.

The atomizing nozzle means 211 of the apparatus 212 is installed immediately ahead of or close to the inlet of the tunnel 249. This nozzle means is preferably a composite nozzle which consists or may consist of an entire battery or row of discrete nozzles 211 a. The row of nozzles 21 1a extends transversely of the direction of transport of tobacco particles 259 through the tunnel 249. The additive which is atomized by the nozzles 211 a is water or another liquid substance.

The mode of operation of the apparatus 212 is the same as that of the apparatus 12 or 212. FIG. 3 does not specifically show a pump in the conduit 213 but it will be readily appreciated that the feeding device 214 contains a source of water (e.g., a water tap) as well as a pumpr such as a gear pump or another pump whose rate of delivery can be varied in dependency on the speed of the prime mover 252 so as to ensure that each increment of the fluidized stream 261 of tobacco particles 259 receives the same quantity of additive The check valve 221 in the conduit 219 opens only during starting and on stoppage of the apparatus 212, i.e., when the pressure of additive in the conduit 213 downstream of the check valve 222 is less than the pressure of gaseous fluid in the conduit 219. The pressure of gaseous fluid in the conduit 219 is selected try the regulating valve 226.

A machine wherein the particles of tobacco are caused to form a fluidized bed or stream is disclosed in commonly owned U.S. Pats. Nos. 3,799,176, 3,957,063, 4,004,594,4,116,203 and 4,195,647. The disclosures of these patents are incorporated herein by reference.

The reference character 213a denotes a manifold which receives water from the conduit 213 and supplies waterto all of the nozzles 211 a.

Claims (18)

1. Apparatus for contacting tobacco particles, filter material or the like with an atomizable additive, such as water, casing or plasticizer, comprising at least one atomizing element; a source of additive; first conduit means connecting said source with said element; means for conveying additive from said source to said element at a variable pressure; a source of pressurized fluid; second conduit means connecting said source of fluid with said first conduit means between said element and said conveying means; and pressure-responsive means provided in said second conduit means and operative to admit pressurized fluid into said first conduit means in response to a drop of pressure of additive in said first conduit means below a preselected value.

2. The apparatus of claim 1, wherein said element includes an atomizing nozzle.

3. The apparatus of claim 2, wherein said nozzle is a single-material noule.

4. The apparatus of claim 1,wherein said pressure-responsive means comprises a check valve.

5. The apparatus of claim 1, further comprising blocking means provided in said first conduit means between the junction offirst and second said conduit means and said conveying means to prevent the flow of pressurized fluid all the way to said conveying means when said pressure-responsive means admits pressurized fluid into said first conduit means.

6. The apparatus of claim 5, wherein said blocking means includes a device which prevents the flow of pressurized fluid to said conveying means irrespective of the pressure of pressurized fluid in said first conduit means downstream of said blocking means but permits the additive to flow toward said junction when the pressure of additive in said first conduit means exceeds the pressure of pressurized fluid.

7. The apparatus of claim 5, wherein said blocking means comprises a check valve.

8. The apparatus of claim 1, further comprising pressure regulating means provided in said second conduit means upstream of said pressureresponsive means and operative to maintain the pressure of pressurized fluid at the respective side of said pressure-responsive means below said preselected value.

9. The apparatus of claim 1, further comprising shutoff valve means provided in said second conduit means.

10. The apparatus of claim 9, wherein said valve means comprises a manually operable shutoff valve.

11. The apparatus of claim 9, wherein said valve means comprises a solenoid-operated valve.

12. The apparatus of claim 1, further comprising means for transporting the material to be treated past said atomizing element.

13. The apparatus of claim 12, wherein said transporting means comprises a rotary conveyor.

14. The apparatus of claim 12, wherein said transporting means comprises a vibratory conveyors

15. The apparatus of claim 12, wherein said transporting means comprises at least one pair of advancing rolls.

16. The apparatus of claim 1,wherein said conveying means comprises a pump and variable-speed motor means for driving said pump.

17. The apparatus of claim 1, wherein said conveying means comprises a gear pump.

18. Apparatus for contacting tobacco particles, filter material or the like with an atomizable additive, substantially as herein described with reference to and as illustrated in the accompanying drawings.