Valve assembly and method for dispensing gelatinous materials
FIELD OF THE INVENTION 
     This invention relates to delivery of material through a valve, and more particularly to a valve assembly and method for dispensing a gelatinous semisolid material into a receptacle. 
     BACKGROUND OF THE INVENTION 
     Many devices for the delivery of various materials through a valve or nozzle have been described in the art. For example, hose nozzles with constricted outlets for the spraying water from a hose are disclosed in U.S. Pat. Nos. 3,102,691 and 4,840,313. Pneumatic guns for dispensing flowable sealants and adhesives are described in U.S. Pat. Nos. 4,376,498, 5,058,769, and 5,064,098. A filler nozzle and valve with a concave-conoidal non-drip tip for delivering fluids of various viscosities is disclosed in U.S. Pat. No. 4,363,429. A nozzle assembly that includes a wire mesh screen for dripless, splashless dispensing of liquids is described in U.S. Pat. No. 5,188,289. 
     Valve devices for the delivery of air and other gases are also known in the art. For example, U.S. Pat. No. 2,596,909 describes a valve for admitting ventilation air in which a slidable tubular member seats against a conical plug situated in a spherical housing. Also, U.S. Pat. No. 4,721,129 discloses a pressure relief valve for gases which has a spring biased piston which operates internally of the valve to relieve pressure and is then resealed in an air-tight manner. 
     PROBLEM TO BE SOLVED BY THE INVENTION 
     In pre-production testing to develop a formulation employed in the production of photographic materials, gelatin, or addenda having gelatin as one of the ingredients, may be added to the mix contained in a receptacle such as a kettle. Such gelatin may include a dispersion of a dye or a dye-forming coupler that may itself be colored. This addition is frequently carried out by raising the temperature of the gelatin to liquefy it, then pumping it in the molten state into the kettle and metering the quantity delivered. Such a procedure requires a complex array of containers, hoses, pumps, and heaters that must be dismantled and cleaned after each use. It would be highly advantageous to dispense automatically and reproducibly a desired measured quantity of the gelatin as a semisolid gelatinous material directly into the coating mix without the need to liquefy and then pump it into the kettle. This desirable objective is met by the valve assembly and method of the present invention. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, a valve assembly for dispensing a measured quantity of a gelatinous semisolid material into a receptacle comprises: 
     (a) a cylindrical housing having a first end and a second end and a throughbore of circular cross-section, the housing being provided with a piston actuatable by pressure means to move through the throughbore towards the second end; 
     (b) a cap attached at the second end of the housing, the cap being provided with a cylindrical sleeve having a throughbore with a cross-section smaller than the cross-section of the throughbore of the housing; 
     (c) a hollow cylindrical valve body mounted within the throughbore of the sleeve and having an external cross-section slightly smaller than the throughbore of the sleeve, the valve body having a first end and a second end, the first end of the valve body being situated within the sleeve and being provided with retaining means for preventing ejection of the valve body from the sleeve by the pressure means; 
     (d) a sealing member connected to the second end of the valve body and comprising an end having a circular cross-section; and 
     (e) a hollow cylindrical barrel mounted within the throughbore of the sleeve and having an external cross-section slightly smaller than the throughbore of the sleeve, the barrel being slidable from a valve closed position to a valve open position, the barrel having a first end and a second end and encompassing the sealing member, the first end of the barrel being situated within the throughbore of the sleeve in close proximity to the second end of the valve body, the second end of the barrel having an orifice with a cross-section substantially equal to the circular cross-section of the sealing member, the barrel being connected to the valve body by resilient means actuatable by pressure exerted by the gelatinous semisolid material; 
     wherein, in the valve closed position of the barrel, the sealing member is situated within the orifice of the barrel, thereby preventing the dispensing of the gelatinous semisolid material, and in the valve open position of the barrel, the orifice of the barrel is displaced away from the sealing member, thereby allowing the dispensing of the gelatinous semisolid material into the receptacle. 
     Also in accordance with the invention, a method for dispensing a measured quantity of a gelatinous semisolid material from a valve assembly having a known tare mass comprises: 
     (a) introducing a mass of the gelatinous semisolid material into a cylindrical housing included in the valve assembly, the housing having a first end and a second end and a throughbore of circular cross-section, the housing being provided with a piston that is situated in close proximity to the first end and is actuatable by pressure means to move through the throughbore towards the second end; the valve assembly further comprising: a cap attached at the second end of the housing, the cap being provided with a cylindrical sleeve having a throughbore with a cross-section smaller than the cross-section of the throughbore of the housing; a hollow cylindrical valve body mounted within the throughbore of the sleeve and having an external cross-section slightly smaller than the throughbore of the sleeve, the valve body having a first end and a second end, the first end of the valve body being situated within the sleeve and being provided with retaining means for preventing ejection of the valve body from the sleeve by the pressure means; a sealing member connected to the second end of the valve body and comprising an end having a circular cross-section; and a hollow cylindrical barrel mounted within the throughbore of the sleeve and having an external cross-section slightly smaller than the throughbore of the sleeve, the barrel being slidable from a valve closed position to a valve open position, the barrel having a first end and a second end and encompassing the sealing member, the first end of the barrel being situated within the throughbore of the sleeve in close proximity to the second end of the valve body, the second end of the barrel having an orifice with a circular cross-section substantially equal to the circular cross-section of the sealing member, the sealing member being situated within the orifice in a valve closed position, the barrel being connected to the valve body by resilient means; 
     (b) determining a gross mass comprising the tare mass of the valve assembly and the mass of the gelatinous semisolid material introduced into the housing; 
     (c) applying pressure by the pressure means to the piston to impel the piston through the throughbore of the housing to the cap, thereby forcing the gelatinous semisolid material through the sleeve and the valve body into the barrel, wherein the material exerts pressure at the orifice, thereby causing the resilient means to be compressed and the orifice to be displaced away from the sealing member to a valve open position, thereby enabling the dispensing of the measured quantity of gelatinous semisolid material from the valve assembly into the receptacle, the orifice returning to the valve closed position by the action of the resilient means after the dispensing of the measured quantity of material into the receptacle; 
     (d) determining an adjusted tare mass comprising the tare mass of the valve assembly together with the mass of gelatinous semisolid material remaining within the valve assembly; and 
     (e) subtracting the adjusted tare mass from the gross mass, thereby verifying the quantity of gelatinous semisolid material that has been dispensed into the receptacle. 
     ADVANTAGE OF THE INVENTION 
     The present invention enables a measured quantity of a gelatinous semisolid material, such as a gelatin based dye dispersion, to be conveniently and reproducibly dispensed as a gelatinous semisolid into a mix contained in a kettle without the need for heaters, hoses, and pumps to liquefy the gelatin and transport it to the kettle. The valve assembly containing the gelatinous semisolid may be weighed before and after the material has been delivered to the kettle, thereby providing verification of the amount dispensed. The minimal constriction within the valve assembly allows the semisolid to be ejected by application of compressed air at relatively low pressure, and the movement of the barrel and the inclusion, in a preferred embodiment, of concentric grooves at the end of the sealing member enables the gelatinous semisolid to be dispensed without residual material remaining on the exterior of the valve assembly. After use, the assembly may be readily disassembled, cleaned, and reassembled for subsequent use. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded isometric view of the valve assembly. 
     FIG. 2 is an isometric view of the valve body and sealing member that shows the concentric grooves at the end of the sealing member. 
     FIG. 3 is an isometric view of the barrel that shows the tabs at one end. 
     FIG. 4 is an isometric view of the valve body connected to the barrel by coil springs. 
     FIG. 5 is a section view showing the valve body, sealing member, and barrel in the valve closed position. 
     FIG. 6 is a section view showing the valve body, sealing member, and barrel in the valve open position. 
     FIG. 7 is a section view showing the concentric grooves on the end of the sealing member. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As depicted in FIG. 1, the valve assembly 100 for dispensing a gelatinous semisolid material into a receptacle comprises a cylindrical housing 101 provided at the first end with a piston 102 actuatable by pressure means (not shown) to move through the throughbore of the housing to a cap 103. In a preferred embodiment, as shown in FIG. 1, the cap is detachably and sealably connected to the second end of the housing, which further comprises a gasket 104, for example, an O-ring seal. 
     The cap is provided with a cylindrical sleeve 105 having a throughbore with a cross-section smaller than the cross-section of the housing throughbore. The sleeve may be coaxial with the cylindrical housing or, as depicted in FIG. 1, the axis of the sleeve may be canted with respect to the housing axis. Mounted within the sleeve is a hollow cylindrical valve body 106 having an external cross-section slightly smaller than the sleeve throughbore and being provided at one end with retaining means from preventing ejection of the valve body from the sleeve by the pressure means. The other end of the valve body is connected to a sealing member that comprises an end with a circular cross-section. 
     Also mounted within the sleeve is a hollow cylindrical barrel having an external cross-section slightly smaller than the sleeve throughbore. The barrel encompasses the sealing member and has an orifice whose cross-section is substantially equal to that of the end of the sealing member. The barrel is connected to the valve body by resilient means actuatable by pressure exerted by the gelatinous semisolid material within the valve assembly. 
     FIG. 2 is an isometric view of the valve body 106. Attached at one end is a lug 201, which comprises the aforementioned retaining means. The sealing member 202 is connected to the valve body at two diametrically situated points by the bifurcated shank 203. Also shown in FIG. 2 is a plurality of concentric grooves 204 at the end of the sealing member, which grooves minimize dripping of the gelatinous semisolid material. 
     FIG. 3 is an isometric view of the barrel 107, which is provided at one end with diametrically positioned tabs 301, to which the resilient means connecting the barrel to the valve body is attached. 
     FIG. 4 is an isometric view depicting the valve body 106, the barrel 107, and coil springs 401, which comprise the resilient means connecting the valve body at lugs 201 to the barrel at tabs 301. 
     FIG. 5 is a cross-section of the valve body 106 and the sealing member 202 connected by the coil spring 401 to the barrel 107; the circular grooved end of the sealing member is shown situated within the orifice 501 of the barrel in the valve closed position. The pressure of the gelatinous semisolid material at the orifice of the barrel propels the barrel away from the sealing member, the valve open position as depicted in FIG. 6, which allows the material to be forced around the sealing member and through the orifice. When the desired measured quantity of the gelatinous material has been expelled from the valve assembly, the spring relaxes and the barrel returns to the valve closed position. 
     As shown in FIGS. 5 and 6, in a preferred embodiment of the invention a portion of the lower, or second end of the barrel is frusto-conically tapered, thereby defining the circumference of the orifice, whose circular cross-section is substantially equal to the cross-section of the sealing member. The preferred angle of the taper, as measured from the end of the sealing member, is about 45 degrees. The tapered inner surface of the barrel at the orifice causes the gelatinous semisolid material to be dispensed in a narrow conical flow path. 
     As previously described, the circular end of the sealing member comprises a plurality of concentric grooves to minimize dripping of the gelatinous material. FIG. 7 is a cross-section depicting the detail of the grooves, whose walls are disposed at an angle of about 90° to each other. The circular grooves are characterized by pitch whose width is represented by p, inner top lands whose width is represented by m, and an outermost top land whose width is represented by n. In a preferred embodiment, the ratio of pitch width to inner top land width, p:m, and the ratio of inner top land width to outermost top land width, m:n, are each from 3:1 to 5:1. In a more preferred embodiment, the ratio of pitch width to inner top land width, p:m, and the ratio of inner top land width to outermost top land width, m:n, are each from 3.5:1 to 4.5:1. In the most preferred embodiment, the ratio of pitch width to inner top land width, p:m, and the ratio of inner top land width and outermost top land width, m:n, are each 4:1. 
     In operation, the cylindrical housing of the valve assembly is filled with a known quantity of a gelatinous semisolid material. As previously described, this gelatinous semisolid may be gelatin used in the production of photographic materials and may further comprise a dispersion of a dye or a dye-forming coupler that may itself be colored. The piston is placed in the cylinder atop the gelatinous semisolid. A shaft actuatable by, for example, manual means such as a crank or a lever, by a linear motor, by hydraulic pressure or, preferably, by compressed air drives the piston through the throughbore to the cap. The minimal constriction within the valve assembly enables a desired measured quantity of gelatinous material to be ejected at relatively low air pressure. The gelatinous semisolid material is forced through the sleeve into the valve body and the barrel. The pressure of the semisolid material at the orifice of the barrel causes the coil spring resilient means connecting the barrel to the valve body to extend, enabling the barrel to move from the valve closed position to the valve open position, resulting in the reproducible dispensing of the desired quantity of gelatinous material into the receptacle. After the desired quantity of material has been ejected from the valve assembly, the spring resilient means relaxes and the barrel returns to the valve closed position. The grooves at the end of the sealing member discourage adherence of the gelatinous material to the end of the sealing member, thereby minimizing dripping. This discouraged adherence also promotes reproducibility in the amount dispersed. That is, since the amount of material adhering to the valve may be different for each usage, the dispersing precision would be impaired. If no material adheres, this variability in the system is reduced, thereby improving the precision. 
     The tare mass of the valve assembly can be determined prior to introduction of a quantity of semisolid material by means known to those skilled in the art, such as a scale or balance. A gross mass comprising the tare mass and the mass of the semisolid material contained in the housing can similarly be determined by such known means. Following the dispensing of the material into the receptacle, an adjusted tare mass comprising the tare mass and any residual gelatinous material remaining within the valve assembly can be ascertained. The difference between the adjusted tare mass and the gross mass can then be determined to verify that the desired measured quantity of gelatinous semisolid material has been dispensed into the receptacle. That is: Semisolid Material Mass=Gross Mass-Tare Mass. Following use, the valve assembly can be readily disassembled, cleaned, and reassembled for subsequent use. 
     The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 
     PARTS LIST 
     100 valve assembly 
     101 housing 
     102 piston 
     103 cap 
     104 gasket 
     105 sleeve 
     106 valve body 
     107 barrel 
     201 lug 
     202 sealing member 
     203 bifurcated shank 
     204 concentric grooves 
     301 tab 
     401 Coil spring 
     501 orifice