Patent Application
20050035153
Not Applicable
Not Applicable
This invention relates to a multi-component fluid mixing and dispensing device in which two or more fluid components are mixed and dispensed from the device as a settable fluid through a nozzle, and more particularly to a mixer and dispenser having a mixing enhancement for enhancing the mixing of the fluid components.
Manually operable guns are known for dispensing a settable urethane foam. Separate fluid components are fed individually to the gun, passed separately through control valves, and brought into contact with each other upon reaching a mixing chamber of a nozzle from which the mixed components are discharged as foam. Examples of such guns are found in U.S. Pat. Nos. 4,311,254 and 4,399,930 issued to Gary Harding and in U.S. Pat. No. 4,762,253 issued to Steven Palmert.
The two fluid components are commonly referred to as the “A resin” and the “B resin”. They usually consist of polymeric isocyanate and polyol, respectively. In one particular dispensing device, the components are supplied separately and are attached by hoses to inlets on the guns. When the two fluid components or resins are mixed, the mixture quickly sets up to form a rigid foam product which is substantially insoluble and extremely difficult to remove from surfaces with which it comes in contact. As a result, the mixing nozzles for the guns in which the two components are first mixed are typically designed to be replaceable and disposable so as to avoid the necessity for cleaning the nozzles.
Foam quality is dependent upon the extent of the mixing of the fluid components. As a result, molded mixing nozzles incorporating a static mixer have been developed and are well known in the art. These static mixers typically include baffles or helical walls that elongate the flow path of the fluid components to provide more time for the fluid components to mix prior to being expelled from the nozzle. Other versions provide baffles which weave the liquids together as they travel the path of the mixing chamber. Still others work in a combination of impinging of the components upon each other.
These static mixers are generally adequate for mixing fluid components of a multi-component foam under ideal conditions. However, typical static mixers produce unacceptable results under adverse conditions, such as cold temperatures, low flow rates, and the like, and when mixing foam components having physical characteristics, such as high viscosity, low flowability, and the like. Of course, longer static mixers further increase the mixing flow path to provide additional time for mixing the fluid components can be provided. However, this solution increases the size of the nozzle and results in wasting foam. Accordingly, a need exists for an improved multi-component foam dispensing gun with mixing enhancement.
The present invention provides a multi-component fluid dispensing device a defining a mixing flow path for mixing at least two fluid components. At least one mixing screen is disposed in the mixing flow path to enhance mixing of the fluid components.
A general objective of the present invention is to provide a multi-component fluid dispensing device having enhanced mixing. This objective is accomplished by inserting a mixing screen in the mixing flow path.
The foregoing and other objectives and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims herein for interpreting the scope of the invention.
The multi-component fluid dispensing device disclosed herein is substantially identical to the foam dispensing gun disclosed in U.S. Pat. No. 5,462,204 with the exception that, as described below, a mixing screen is disposed in the flow path of the foam components to enhance mixing of the foam components. U.S. Pat. No. 5,462,204 is assigned to the assignee of the present invention, and is fully incorporated herein by reference.
References to foam and foam components, herein, encompass any multi-component fluid and the fluid components comprising the multi-component fluid, such as an epoxy comprising a resin and hardener, a silicone comprising a catalyst and resin, and the like. Moreover, the present invention can be used with any thermosetting reactants, such as poly urea, phenolic, and the like without departing from the scope of the invention. In addition, although the foam dispensing gun disclosed herein is preferred, any multi-component fluid dispensing device having a nozzle through which a multi-component fluid is dispensed can be used without departing from the scope of the invention.
Referring to
The connectors 15 are hollow and define passageway inlets leading from the tanks of components. The bushings 22 are also hollow and mount duck-bill valves 25 in their center. The duck-bill valves 25 are formed of a rubber or other elastomeric material and function as one-way valves to permit fluid under pressure to enter a passageway 12 or 13.
Each bushing 22 is disposed against a bellville spring 26 which bears against an end of the respective connector 15 thereby urging the bushing 22 inwardly in the passageway 12 or 13 until it abuts against a shoulder 27. A coiled spring 30 is disposed in each of the passageways 12 and 13. The spring 30 bears at one end against an end of a respective bushing 22. The other ends of the springs 30 bear against the ends of brass needle valve members 31 also disposed in the passageways 12 and 13.
The needle valve members 31 span the chamber 14 and are received in both the forward and rearward portions of the passageways 12 and 13. The needle valve members 31 have a rear portion provided with a radial recess 32 that mounts an O-ring 33 to seal with the rearward portion of the passageway 12 or 13. The forward portion of each valve member 31 is formed as a conical needle valve 35 portion terminating in a circular cylindrical tip 36. The conical needle valve portion 35 and tip 36 mate with a conical valve seat 37 having a circular cylindrical extension 38 and formed in the body 10 at the front terminus of the passageways 12 and 13.
The valve seats 37 define passageway outlets, and open directly through the front face of a nose 40 on the body 10. The valve members 31 have an annular recess 39 behind the conical needle valve portion 35. The recess 39 mounts an O-ring 41 that seals the junction of the needle valve portion 35 and the conical valve seat 37 when the valve is closed, as shown in
The chamber 14 mounts a yoke 50 formed at the top of a trigger lever 51. The yoke 50 has a pair of arms 52 terminating in lateral bosses 53 that are received for pivotal movement in holes 54 in the two sides of the body 10, as shown in
Each valve member 31 has a central internal passage 60 that terminates in a transverse port 61 that extends to the surface of the valve member at a point between the O-rings 40 and 46. As shown in
A disposable nozzle 65 is mounted on the front of the gun. The nozzle 65 has a hollow interior that defines a mixing chamber 66 and interposed between a nozzle inlet 63 and a nozzle outlet 67. A helical static mixer 68 of known construction is mounted in the mixing chamber 66. The rear end of the nozzle upstream of the mixing chamber 66 has an enlarged circular cylindrical portion 69 which surrounds the nose 40 of the body 10 and is sealed thereto by an O-ring 70. The cylindrical portion 69 also defines the open nozzle inlet 63. An annular ring 80 formed around the nozzle 65 proximal the outlet 67 provides grasping surfaces for securely grasping the nozzle 65 when attaching and detaching the nozzle 65 from the gun body 10. External threads 82 are formed on the nozzle 65 forward of the annular ring 80 for threadably engaging a detachable spray tip 84, such as shown in
A pair of resilient arms 71 extend along either side of the nozzle rearwardly from the enlarged cylindrical portion 69. The resilient arms 71 are adapted to engage ears 72 that extend from opposite sides of the body 10 adjacent the nose 40. The resilient arms 71 have a curved portion 73 adjacent their ends which terminates in a notch 74 that mates with an ear 72. The nozzle can be quickly attached to the body 10 by sliding the resilient arms 71 beneath the ears 72. The curved portions 73 will cam the arms 71 so that the arms will slide easily past the ears 72 until the notches 74 engages with the ears 72. The nozzles 65 can be easily removed by manually depressing the curved ends 73 of the arms 71 to release the notches 74 from the ears 72 and allow the arms 71 to slide past the ears 72. Although detachably fixing the nozzle to the body is preferred, as described above, the nozzle can form an integral and/or permanent part of the body, or be detachably fixed to the body using other methods, such as by using a threaded engagement, snap fit, friction fit, fasteners, and the like, without departing from the scope of the invention.
The static mixer 68 includes a wall portion 76 which is located in the open nozzle inlet 63 defined by the enlarged cylindrical end 69 of the nozzle. As shown in
Referring now to
Opposing wings 96 extending radially from the spray tip 84 provide engagement surfaces for rotating the spray tip 84 to threadably engage the internal threads 90 with the external threads 82. Of course, other means can be provided for securely grasping the spray tip to detachably fix the spray tip to the nozzle end, such as a single wing, a knurled exterior surface, a geometric external cross section for engaging a wrench, and the like, without departing from the scope of the invention.
The foam components flow from the passageway outlets along a mixing flow path through the nozzle 65, out of the nozzle outlet 67, and through the spray tip 84. A mixing screen 100 disposed in the mixing flow path, and positioned such that foam components pass through the mixing screen 100, enhances the mixing of the foam components. Preferably, the mixing screen 100 is a wire mesh screen which is commercially available in many different mesh sizes and materials. Although a wire mesh screen is preferred, the mixing screen can be a perforated plate, molded plastic, stamped plate, and the like without departing from the scope of the invention.
In one embodiment shown in
The mixing screen 100 defines a shear profile that provides shear in the foam components as they pass through the mixing screen 100 to enhances mixing without the need to increase the length of the flow path. The shear created by the shear profile increases mechanical stress in the foam components as they flow along the flow path. Advantageously, the increased mechanical stress enhances mixing in high viscosity foams components that do not traditionally mix well, as well as, lower viscosity foam components.
Planar mixing screens, such as shown in
In certain applications, if a single mixing screen 100 does not provide sufficient enhanced mixing, a plurality of mixing screens 100 disposed in the flow path can be provided, such as shown in
In another embodiment incorporating the present invention shown in
The openings 112, 113 formed in the closed end 123, 125 of each barrel 111, 115 define a fluid passageway in fluid communication with a mixing nozzle 165. Each passageway fluidly connects the respective barrel 111, 115, and thus the fluid components disposed in the barrel 111, 115, to the mixing nozzle 165, and can be as short as an aperture formed through the barrel wall, or as long as necessary to fluidly connect the source of fluid component to the mixing nozzle 165.
The mixing nozzle 165 includes a nozzle inlet 163 and a nozzle outlet 167, and the fluid components are mixed along a mixing flow path defined between the nozzle inlet 163 and nozzle outlet 167. The mixing nozzle 165 can be formed as an integral part of the body 110 or be detachable from the body 110 without departing from the scope of the invention.
A static mixer 168 disposed in the mixing flow path between the nozzle inlet 163 and nozzle outlet 167 mixes the fluid components to form the multi-component fluid. Although a static mixer 168 is disclosed and preferred, the fluid components will mix in the mixing nozzle 165 without the static mixer 168. Accordingly, the static mixer 168 can be eliminated, or replaced with a different type of mixer, without departing from the scope of the invention.
A mixing screen 200, such as described above, is disposed in the flow path to further enhance mixing the fluid components. In the embodiment shown in
A syringe-type multi-component fluid dispenser, as described above with reference to
While there has been shown and described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention defined by the appended claims.
