Abstract:
A plural component dispensing system  10  receives separate fluid components, mixes the components in a predetermined ratio, and dispenses the components as mixture. Each fluid component is supplied by a separate pump  12 A,  12 B to an individual variably controllable fluid regulator  14 A,  14 B. Each fluid component is supplied from its individual fluid regulator  14 A,  14 B through a flow meter  18 A,  18 B to a mixing device  20 . The ratio of the components delivered to the mixing device  20  is controlled by the individual fluid regulators  14 A,  14 B based upon the flow rates measured by the flow meters  18 A,  18 B.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims priority from U.S. Provisional Application Ser. No. 61/816,265, filed Apr. 26, 2013, entitled PLURAL COMPONENT PROPORTIONER AND REGULATOR, which is incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to plural component dispensing systems, and more particularly to a system to take multiple material components and proportion them accurately to a specified mixed ratio. 
         [0003]    Fluid proportioners comprise dispensing systems that receive separate inert fluid components, mix the components in a predetermined ratio and then dispense the components as an activated compound. For example, fluid proportioners are used to dispense epoxies and polyurethanes that solidify after mixing of a resin component and an activating material, which are individually inert. However, after mixing an immediate chemical reaction begins taking place that results in the cross-linking, curing, and solidification of the mixture. Therefore, the two components are routed separately into the proportioner so that they can remain segregated as long as possible. A manifold receives each component after it is pumped separately and mixes the components so the mixture can be dispensed from a sprayer coupled to the manifold. 
         [0004]    A typical fluid proportioner comprises a pair of positive displacement pumps that individually draw in fluid from separate fluid hoppers and pump pressurized fluids to the mix manifold. The pumps are driven in synchronicity by a common motor, typically an air motor or hydraulic motor, having a reciprocating drive shaft. Such configurations are simple and easy to design when the fluid components are dispensed in a 1:1 ratio and the pumps are of equal volumetric displacement. Force balancing in these configurations can be adequately accommodated by placing the motor halfway between the pumps. As such, forces generated between the pumps and the motor are equal. 
         [0005]    Most two component epoxies and polyurethanes are not, however, comprised of a 1:1 ratio of the components. Typically a first major component is needed in a higher concentration than a second minor component. 
       SUMMARY 
       [0006]    A system for providing a mixture produced from separate fluid components includes a plurality of positive displacement pumps, a plurality of fluid regulators, a plurality of flow meters, a receiving device, and a control system. Each pump delivers a separate fluid component, and each fluid regulator is connected to one of the pumps for regulating fluid pressure of one of the fluid components. Each flow meter is connected to one of the fluid regulators for sensing flow rate of one of the fluid components. The receiving device receives the separate fluid components. The control system controls the fluid regulators based on the measured flow rates to produce a desired mix ratio of the separate fluid components. 
         [0007]    The method of producing a mixture based upon separate fluids includes pumping a plurality of separate fluids, sensing flow rate of each of the separate fluids, delivering the separate fluids to a receiving device, and individually regulating fluid pressure of each of the separate fluids as a function of flow rate sensed to produce a desired ratio of the separate fluids at the receiving device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a block diagram of a two component fluid proportioning system with independent variable fluid regulators and individual flow meters. 
           [0009]      FIG. 2  is a block diagram of a multiple material mix system for treating a plurality of fluid materials delivered from individual pumps through variable controlled fluid regulators and flow meters to a mixing device. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]      FIG. 1  is a block diagram of fluid proportioning system  10 , which may be used, for example, in a multicomponent spray system. In the particular embodiment shown in  FIG. 1 , system  10  is designed for a two component mix application in which two separate inert fluid components are mixed in a predetermined ratio and then dispensed as an activated compound. The two components will be referred to as the base fluid component and the catalyst fluid component. 
         [0011]      FIG. 1  includes base pump  12 A and catalyst pump  12 B, base fluid regulator  14 A and catalyst fluid regulator  14 B, base actuator  16 A and catalyst actuator  16 B, base flow meter  18 A and catalyst flow meter  18 B, mixing device  20 , and controller  22 . Base fluid material is pumped under pressure by base pump  12 A to base fluid regulator  14 A, which regulates the fluid pressure of the base material in response to base actuator  16 A. The base material flows from base fluid regulator  14 A through base flow meter  18 A to mixing device  20 . Base flow meter  18 A senses the flow rate of the base material as it flows to mixing device  20 . 
         [0012]    The catalyst fluid component is pumped under pressure by catalyst pump  12 B to catalyst fluid regulator  14 B. The fluid pressure of the catalyst fluid component is regulated by catalyst fluid regulator  14 B under the control of actuator  16 B. The catalyst fluid component is delivered from catalyst fluid regulator  14 B through catalyst flow meter  18 B to mixing device  20 . 
         [0013]    At mixing device  20 , the base and catalyst components are mixed, which produces an immediate chemical reaction. The reacted mixture is delivered by the mixing device  20  to a dispenser (not shown). 
         [0014]    Depending on the base and catalyst materials being used, the mix ratio between the base and catalyst materials can vary significantly. Often the base material is the major component and is required at a much higher concentration than the catalyst component. In system  10 , base fluid regulator  14 A and catalyst fluid regulator  14 B are controlled by actuators  16 A and  16 B to produce the desired mix ratio for the particular base and catalyst materials being used. The control of the mix ratio is based upon the sensed flow rates of the base and catalyst materials produced by base flow meter  18 A and catalyst flow meter  18 B, respectively. 
         [0015]    In one embodiment, base fluid regulator  14 A and catalyst fluid regulator  14 B are air controlled fluid regulators. Actuators  16 A and  16 B provide air pressure to regulators  14 A and  14 B, respectively, in order to set the regulated fluid pressure of the base and catalyst materials, respectively. In one embodiment, actuator  16 A is a manually set air regulator, and is capable of producing a variable air pressure of between 0 and 85 psi. Actuator  16 B is an electrically controlled air regulator that can vary air pressure from 0 to 85 psi based upon a variable electrical control signal from controller  22 . The control signal, for example, may be a variable voltage of between 0 and 10 volts. 
         [0016]    In the embodiment in which actuator  16 A is a manual air regulator and actuator  16 B is an electrically controlled air regulator, an operator will set manual air regulator  16 A to produce a desired regulated fluid pressure at the output of regulator  16 A. With that regulated fluid pressure, a flow rate of base material from regulator  14 A to mixing device  20  is established and is measured by base flow meter  18 A. Catalyst fluid regulator  14 B is controlled by controller  22  through actuator  16 B so that the flow rate of catalyst material is scaled to the flow rate of the base material. The scaling factor used is based upon a desired target ratio of base to catalyst needed by mixing device  20  to produce the desired mix of reacted fluid. Controller  22  may receive feedback signals from base flow meter  18 A and catalyst flow meter  18 B in order to provide a control signal to actuator  16 B that will result in a regulated fluid pressure at the output of regulator  16 B that results in a catalyst flow rate that will produce the desired target ratio. Alternatively, an operator may read the flow rates produced by the base and catalyst flow meters  18 A and  18 B and provide a control input to controller  22 . 
         [0017]    In system  10 , the catalyst flow rate tracks the base flow rate. As a result, the overall flow rate of material supplied by mixing device  20  is dictated by adjustment of base actuator  16 A, which may be a manual air regulator adjusted by the operator. In that case, the operator would adjust actuator  16 A manually until a desired base flow rate is measured by flow meter  18 A and would supply an input indicating the desired target ratio to controller  22 . 
         [0018]    System  10  provides a number of advantages. System  10  is not concerned with the supply system that is feeding it base and catalyst material. The operation of pumps  12 A and  12 B do not need to be synchronized, and can have different pump output pressures. Regulators  14 A and  14 B act as accumulators to dampen out material pressure variations and disturbances that can occur, for example, during a pump change-over or during air supply changes. 
         [0019]    Although system  10  has been described as implemented using variable air pressure regulators, the regulators can alternatively be controlled electrically or hydraulically. 
         [0020]    Using feedback from flow meters  18 A and  18 B, system  10  can maintain the desired target ratio using regulation of fluid pressure by regulators  14 A and  14 B. By using separate regulators and flow meters for each individual material, proper ratio regulation can be achieved. 
         [0021]    In the preferred embodiment, the predominant material (often referred to as the “resin” or “base” or “A” material) is regulated to a fixed flow by setting the associated fluid regulator to a fixed setting. Both materials are supplied under pressure by simple supply pumps at pressures (e.g. 5000 psi) substantially above the level at which they will be dispensed. The regulator on the A side regulates the fluid pressure down to that level (e.g. 2000 psi) which will produce the desired flow. The controller then looks at the flow produced on the A side and regulates the fluid regulator on the B side to produce the desired flow on that side commensurate with the ratio required by the material being used. 
         [0022]    For example, materials may have ratios between the A and B sides of anywhere from 1:1 to 10:1 or even more. In this example, it is desired to regulate the B side to a similar pressure as the A side to assure the desired ratio is maintained. By regulating controlled flow through the flow meters to a pressure level substantially below that produced by the supply pumps, pressure variations due to changeover or other factors are effectively eliminated. 
         [0023]      FIG. 2  shows system  30 , which is an N component mixing system in which N individual fluid components are mixed. System  30  includes pumps  32 A- 32 N, fluid regulators  34 A- 34 N, actuators  36 A- 36 N, flow meters  38 A- 38 N, mixing device  40 , and controller  42 . 
         [0024]    In system  30 , each individual component (which may be referred to as components A through N) is delivered separately to mixing device  40 . For example, component A is delivered at high pressure from positive displacement pump  32 A to fluid regulator  34 A. The output of regulator  34 A is a variable regulated fluid pressure. Component A is supplied from regulator  34 A through flow meter  38 A to mixing device  40 . The regulated fluid pressure is determined by an actuating signal, which may be electrical or mechanical from actuator  36 A to regulator  34 A. Flow meter  38 A provides a flow rate signal FRA representing measured flow rate of component A to controller  42 . Actuator  36 A is responsive to actuator control signal ACTA from controller  42 . 
         [0025]    Similarly, component B is supplied from pump  32 B to mixing device  40  through regulator  34 B and flow meter  38 B. Actuator  36 B controls the variable fluid pressure provided by regulator  34 B based upon an actuator control signal ACT B from controller  42 . Flow meter  38 B provides measured flow rate signal FRB to controller  42 . 
         [0026]    Component N is supplied under pressure from the positive displacement pump  32 N to regulator  34 N, which is controlled by actuator  36 N. Component N flows through flow meter  38 N to mixing device  40 . Flow rate signal FRN is supplied by flow meter  38 N to controller  42 . 
         [0027]    Controller  42  supplies actuator control signals ACTA-ACTN to actuators  36 A- 36 N based upon desired target ratio input information and flow rate feedback signals FRA-FRN received from flow meters  38 A- 38 N, respectively. 
         [0028]    System  30  individually controls the regulated fluid pressure and thus the flow rate of each of the components in order to establish and maintain the desired target ratio of the components that are mixed in mixing device  40 . In addition, controller  42  can control the flow rates of all of the components individually so that the desired output flow of the mixture to the dispenser is maintained. 
         [0029]    The flow meters used with this invention may measure flow directly or indirectly. Examples of flow meters using direct measurement include typical industry flow meters such as gear meters and coriolis mass flow meters. Indirect measurement can be achieved, for example, by measuring position displacement of a pump and finding correlations to provide a flow measurement. 
         [0030]    The fluid regulators can take a variety of forms. For example, the fluid regulators may regulate flow by controlling a variable orifice. A larger orifice provides less pressure drop, while a smaller orifice provides more pressure drop. Another type of flow regulator includes an on/off valve, with the flow being regulated by how long the valve stays open. 
         [0031]    The invention can also be used without including a mixer for some applications. An example is a method and system for filling separate cartridges to a specific ratio. Each cartridge (rather than a mixer) is the receiving device for receiving the separate components. 
         [0032]    While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.