referring now in detail to the drawings wherein like parts are designated by like reference numerals throughout , there is illustrated in fig1 a schematic view of a continuous , multifilament filter rod - making apparatus which is designated generally by reference numeral 10 . a continuous multifilament filter tow 12 , such as a cellulose acetate tow , is drawn from a filter tow supply 14 by paired feed rolls 16 , 18 . the tow 12 is passed through a pneumatic banding jet 20 and over a guide roll 22 before reaching the feed rolls 16 , 18 . after being substantially flattened by the feed rolls 16 , 18 , the tow 12 is passed between a pair of wick - type plasticizer applicators 24 , 26 . the plasticized filter tow 12 is then passed through a blooming device 28 of conventional design which loosens and blooms the filter tow 12 by subjecting it to tension created by a rapidly moving stream of gas ( not shown ) thereby producing a longitudinally oriented assembly of filaments having individual filaments of the tow in substantial alignment . the plasticized and bloomed tow 12 is then advanced from the blooming device 28 by paired delivery rolls 30 , 32 and directed to a converging horn 34 which converges the tow and feeds it to the tongue injection device 40 of the present invention where a fluid is injected into the tow as will be more fully described hereinafter . downstream of the tongue injection device 40 , there is arranged the garniture 41 of the filter rod - making apparatus 10 . the garniture 41 operates as follows . a continuous paper web 42 from a paper supply roll 44 passes over a guide roll 46 beneath the converging horn 34 and tongue injection device 40 and into a rod forming means 48 . the converging horn 34 gathers and condenses the bloomed filaments transversely to the direction of the filter tow path and passes the compressed tow through the tongue injection device 40 . while undergoing further compression and compaction by the rod forming means 48 , the tow is wrapped by the paper web 42 which is carried simultaneously with the tow into the rod forming means 48 by an endless conveyor belt 50 . the paper web 42 is formed into a substantially cylindrical configuration as it passes through the rod forming means 48 . the conveyor belt 50 is driven by a plurality of guide rolls 52 and an operatively connected drive means ( not shown ). the formed and wrapped filter rod 54 is withdrawn from the rod forming means 48 by a pair of transport rolls 56 , 58 and subsequently cut into sections 60 of desired length by a cutting apparatus 62 . according to the first embodiment of the invention , during operation of the rod - making apparatus 10 , a liquid additive , such as a flavorant , from an additive supply reservoir 64 is fed by a pump 66 via a throttle valve 65 and shut - off valve 67 through a conduit 68 into a first inlet 70 of the tongue injection device 40 of the present invention . the injection of the liquid additive is preferably accompanied by the injection of a gaseous fluid , such as pressurized air , for atomizing the liquid additive for injection into the tow . if a gaseous fluid is used to atomize the liquid additive , a pressurized gas supply 72 , e . g ., air , is fed via a throttle valve 74 and shut - off valve 75 through a conduit 76 into a second inlet 80 of the tongue injection device 40 . now referring to the embodiment of the invention shown in fig2 - 5 , the tongue injection device 40 comprises a tongue portion 82 , which is similar in construction and function to the tongue device of a conventional filter rod - making apparatus . the tongue portion 82 is an elongated converging channel member having a wall formed with an inverted , generally u - shaped cross - section as is well known in the art . the tongue injection device 40 is fixedly secured to the garniture 41 in a manner well known in the art . a nozzle block 84 is integrally formed with or affixed to the tongue portion 82 adjacent the upstream end thereof . nozzle block 84 includes a narrow streamlined portion 83 which extends downwardly into the converging channel or throat of the tongue portion 82 so as to be rigidly fixed in the path of travel of the filter tow as it is advanced through the tongue portion 82 . the upstream end 85 of the nozzle block 84 is rounded and streamlined so as to minimize friction and drag between the nozzle block and the advancing tow . a nozzle conduit 86 is formed at the lowermost extremity of the nozzle block 84 such that the longitudinal axis of the conduit 86 is substantially parallel to the longitudinal axis of the tongue portion 82 . the conduit 86 comprises a blind bore formed in the nozzle block 84 with the upstream end of the bore closed and sealed by a threaded plug 88 . the upper portion 90 of the nozzle block 84 is provided with a threaded bore 92 which communicates with the nozzle conduit 86 by a passage 94 . an atomizer 71 is threaded into bore 92 and carries the first and second inlets 70 , 80 for a liquid additive and a pressurized gas supplied from conduits 68 , 76 , respectively . atomizer 71 may be of any conventional construction suitable for atomizing the liquid additive with the pressurized gas . one such construction may be a capillary tube for introducing the liquid additive into the pressurized gas stream as described in the aforesaid u . s . pat . no . 4 , 549 , 875 . referring now to fig4 and 5 , the arrangement of the nozzle feed holes will be described . a plurality of feed holes 96 is spirally arrayed about the lower , rounded portion of the nozzle block 84 upstream of the junction between the nozzle conduit 86 and the passage 94 . each feed hole 96 is spaced one from the next by a longitudinal distance a . as shown in fig5 eight feed holes 96 are equi - angularly spaced apart one from the next by an angular displacement b over approximately a 180 ° portion of the lower periphery of the nozzle block 84 . in the embodiment shown , the angle b is about 22 . 5 degrees so that the array of feed holes 96 extends over a total arc of about 157 . 5 degrees between the centers of the holes at each extremity of the spiral array . in one construction according to the invention , the eight feed holes 96 each have a diameter of 0 . 02 inch and the distance a spacing is 0 . 05 inch . alternative combinations of the number , size , spacing and arrangement of the feed holes 96 is possible within the scope of the invention . it has been found that a pressure of about 20 psi is effective for proper atomization of a liquid additive , such as a flavorant . according to the second embodiment of the invention , a gaseous fluid , such as air , is injected from pressurized gas supply 72 via throttle valve 74 , shut - off valve 75 and through conduit 76 into the second inlet 80 of the tongue injection device 40 . the pump 66 is shut down so that no additive is introduced into the first inlet 70 and , preferably , shut - off valve 67 is closed to prevent any flow through conduit 68 to the tongue injection device 40 . it is not necessary to use atomizer 71 in the second embodiment of the invention and the atomizer may be removed if desired . however , if the atomizer does not excessively restrict the flow of gas or air to the tongue injection device 40 , it may be left in place when practicing the process of the second embodiment of the invention . it has been found according to the process of the second embodiment that introduction of air at a pressure in the range of about 20 - 70 psi into the tow at or adjacent the longitudinal axis of the tow provides an additional or secondary blooming of the tow to an extent sufficient to reduce the required volumetric input of tow for a given length of filter rod manufactured . while an air pressure range of 20 - 70 psi has been found effective in one construction of the invention , it is contemplated that a greater or lesser pressure may be used depending , among other things , on the type of filter material being processed , the particular design of the nozzle conduit , nozzle holes , and the like . it should be apparent from the foregoing description that the present invention provides an improved apparatus for injecting fluids into a continuous multifilament filter tow at a precise location along or adjacent the longitudinal axis of the filter tow . fig6 illustrates a cross - sectional view of the finished filter rod 54 wrapped with paper web 42 . the central area d shows the location of an additive introduced into the filter tow 12 by means of the tongue injection device 40 of the present invention . it is also contemplated within the scope of the present invention that the tongue injection device could be constructed to position an additive in any desired location relative to the longitudinal axis of the filter tow . in addition , the additive may be supplied to the filter rod intermittently or periodically by pulsing the injection pressures of the additive and the pressurized gas . although certain preferred embodiments of the invention have been described herein , it will be apparent to those skilled in the art to which the invention pertains that variations and modifications of the described embodiment may be made without departing from the spirit and scope of the invention . accordingly , it is intended that the invention be limited only to the extent required by the appended claims and the applicable rules of law .
a fluid injection device and method of injecting and distributing a fluid , such as a gas , liquid or combination thereof , to a continuous , multifilament filter tow used in the manufacture of filters for smokable tobacco products . the injection device includes a converging tongue portion from which a nozzle block is suspended and rigidly supported . a nozzle conduit with a plurality of feed holes is formed in the nozzle block for delivering the fluid to a precise location in the advancing filter tow during its formation and consolidation into a filter rod . additives , such as flavorants , may be injected into the tow or the tow may be further bloomed by a gas , such as air , to decrease tow usage .