Abstract:
A liquid additive injection pump for injecting a predetermined amount of a secondary fluid into a primary fluid stream wherein a fluid mixing chamber is disposed within the pump housing assembly. A gasket having at least one one-way valve is positioned between the pump assembly components and mixing chamber thereby allowing a primary fluid to pass through the pump assembly and into the mixing chamber where the introduction of a second fluid occurs. The mixed fluids are then discharged through an outlet. The one-way valve gasket assembly acts to prevent the mixed and/or secondary fluid from passing upstream of the gasket assembly and into the pump assembly.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Technical Field  
         [0002]     The present invention relates generally to a liquid additive injection pump for injecting a predetermined amount of a secondary fluid into a primary fluid stream, said pump driven by a fluid powered motor. More specifically, the present invention relates to a liquid additive injection pump having an external mixing chamber separated from the fluid-powered-motor components by a one-way valve gasket assembly.  
         [0003]     2. Description of Related Art  
         [0004]     Fluid powered motors driving an additive injection pump connected to a source of fluid additives are typically installed in a line containing primary fluid under pressure. The primary fluid produces reciprocating movement of a piston assembly within a housing of the fluid motor. The fluid motor in turn reciprocates a piston within a cylinder of the additive injection pump to draw a quantity of secondary fluid into the primary fluid. Such devices have been applied to add medication to drinking water for poultry and livestock, treat water with additives, add fertilizer concentrate to irrigation water, or add lubricant or cleaning agents to water. In liquid additive injection pumps, such as that shown in U.S. Pat. No. 4,558,715, reciprocating movement of the piston assembly is produced by a valve mechanism operable to establish a differential pressure. Specifically, opening and closing of the valve mechanism synchronized to the upstroke and down stroke positions of the piston assembly produces a pressure differential that moves the piston through its reciprocating cycle. Opening and closing of the valve mechanism is synchronized to the piston assembly by an over-center mechanism, which is actuated coincident with the piston assembly reaching the ends of its upstroke and down stroke positions. The over-center mechanism is spring-biased and serves to toggle the valve mechanism open and closed when an actuating shaft carried by the piston assembly engages stops that define the ends of its upstroke and down stroke excursions.  
         [0005]     Certain fluids, however, can be quite corrosive, and still others may cause corrosive or otherwise harsh chemical reactions when mixed with a second fluid. Corrosive fluids and harsh chemical reactions can damage the pumping elements. Thus, a need exists for a differential-pressure piston-type fluid injection pump having a separate mixing chamber downstream of the pumping/metering elements. Furthermore, a need exists for a simple mechanism for preventing backflow from the separate mixing chamber into the pumping/metering elements.  
         [0006]     Further objects of this invention will be apparent to persons knowledgeable with devices of this general type upon reading the following description and examining the accompanying drawings.  
       SUMMARY OF THE INVENTION  
       [0007]     In accordance with the foregoing objects, the present invention is an apparatus and system for injecting a predetermined amount of a secondary fluid into a primary fluid stream wherein a liquid additive injection pump is driven by a fluid powered motor, which in turn is driven by the primary fluid stream, and can be selectively suspended by an on/off switch mechanism if desired. A pump housing, which contains the pumping components of the fluid powered motor, also contains a mixing chamber apart from the pumping components.  
         [0008]     In a preferred embodiment of the present invention, the fluid powered motor includes a housing enclosing a differential pressure piston assembly having a piston movable within a housing between upstroke and down stroke positions; a valve mechanism establishing a differential pressure within the housing to produce movement of the piston; an over-center mechanism coupled to the valve mechanism to toggle the valve mechanism between open and closed positions; an actuating shaft coupled to the over-center mechanism, the actuating shaft including a piston upstroke stop that causes toggling of the valve mechanism at an upstroke position of the piston during normal reciprocating movement of the piston; a mixing chamber that is in fluid communication with the pump discharge and is separate from the fluid powered motor; a gasket having one or more one-way valves for allowing the primary fluid to pass into the mixing chamber for mixing with the secondary fluid, while preventing the secondary and/or the mixed fluids within the mixing chamber from passing upstream of the gasket into the pump housing.  
         [0009]     Many other features, objects and advantages of the present invention will be apparent to those of ordinary skill in the relevant arts, especially in light of the foregoing discussions and the following drawings, exemplary detailed description and appended claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings wherein:  
         [0011]      FIG. 1  is an elevated side view of an entire pump in a preferred embodiment;  
         [0012]      FIG. 2  is a side cross-sectional view of the entire pump in a preferred embodiment;  
         [0013]      FIG. 3  is a perspective view of upper and lower halves of the pump housing with a one-way-valve gasket in a preferred embodiment;  
         [0014]      FIG. 4  is a side cross-sectional view of the pump housing with a separate mixing chamber;  
         [0015]      FIG. 5  is another side cross-sectional view of the pump shown in  FIG. 4 ; and  
         [0016]      FIGS. 6   a - 6   f  are five views of the one-way-valve gasket in preferred embodiment.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     A preferred embodiment of the invention is disclosed herein as shown in  FIGS. 1 through 6   f.    
         [0018]      FIG. 1  is an elevated side view of an entire pump in a preferred embodiment, and  FIG. 2  is a side cross-sectional view of the pump shown in  FIG. 1 . In  FIGS. 1 and 2 , a fluid powered motor  10  is shown. A housing  12 , including cover  12 A and lower body  12 B, which are secured together at their interface  12 C and internally separated by one-way-valve gasket, encloses the fluid powered motor components. An inlet conduit  14  provides for acceptance of a primary fluid stream, and an outlet conduit  16  discharges the primary fluid stream. Coupled to the fluid powered motor  10  is a liquid additive injection pump  18 . An inlet conduit having a fitting  20  provides for acceptance of a liquid additive. The liquid additive is drawn into the pump  18  from an additive reservoir (not shown) and injected into the primary fluid stream. Metering of the liquid additive is adjustable by a ratio adjustment sleeve  22 . The liquid additive injection pump  18  includes a dosage piston  23 , which is movable within an inner cylinder  25 A and outer cylinder  25 B by connecting piston rod  27 . The fluid powered motor  10  is coupled to the connecting piston rod  27  to drive the liquid additive injection pump.  
         [0019]     The internal components of the fluid powered motor  10  within housing  12  include a piston assembly  24 . A valve mechanism  26  is carried on the piston assembly  24  and includes four poppet valves  26 , which are shown seated and closing off four respective piston-top channels  54 . The piston itself has a larger-diameter upper part  52  and a smaller-diameter lower part  58 . The lower part of the piston  58  fits precisely but slidably within an inner cylinder wall  62  of the housing lower body  12 . Likewise, the upper part of the piston  52  fits precisely but slidably within the housing cover  12 A. An actuator shaft  28  extends through the piston assembly  24  and is coupled to an over-center mechanism  42  that actuates the valve mechanism  26 . Opening and closing of the valve mechanism  26  at the upstroke and down stroke positions of the piston creates a differential pressure within the housing  12  effective to produce reciprocating movement of the piston assembly  24 . The internal components of fluid powered motor  10  constitute what is termed a “differential pressure reciprocating piston assembly.” 
         [0020]     At the top of the housing  12  is an on/off switch mechanism  32 . A sleeve  34  extends from the top of the housing  12 . An insert  36  (not shown) is axially movable relative to the sleeve  34  by actuation of a cam mechanism  38  using handle  40 . The handle rotates through an arc of  180  degrees as it is thrown from side-to-side between the “on” and “off” positions of the switch mechanism  32 . The switch mechanism  32  is shown in the “on” position in  FIGS. 1 and 2 . In the “on” position of the switch mechanism, the insert  36  is fully inside sleeve  34 . The insert  36  is coupled to the actuator shaft  28  to establish the vertical position of the shaft relative to the housing cover  12 A. Although shown in the figures, an on/off switch can be omitted if desired.  
         [0021]     Also illustrated in  FIGS. 1 and 2  is the coupling of the actuator shaft  28  to the insert  36 . In the illustrated embodiment, the actuator shaft  28  and the insert  36  are integrally formed as a single unit. Cap  44  sits atop the insert  36 . When the switch mechanism is in the “off” position, protrusion of the actuator shaft  28  from the housing cover  12 A provides visual indicia of the condition of the switch mechanism as being “off.” The portion of the actuator shaft  28  that protrudes from the housing cover  12 A may be colored to assist in providing the visual indicia of the condition of the switch mechanism.  
         [0022]     As seen in  FIG. 2 , the actuator shaft  28  includes a circumferential shoulder  46 , which is aligned to be engaged by a collar extension  48  on the piston assembly  24 . As will be appreciated, when piston assembly  24  moves in the upstroke excursion, the inner collar extension  48  will engage the shoulder  46 . When the collar extension  48  engages the shoulder  46 , the valve mechanism  26  is moved to the closed position, and the over-center mechanism  42  is triggered to toggle into a position that maintains closure of the valve mechanism. Upon closure of the valve mechanism, a differential pressure is created that causes the piston assembly to begin moving in the down stroke excursion portion of its reciprocating cycle. In the position of the actuator shaft  28  shown in  FIGS. 1 and 2 , the range of movement of the piston assembly to the end of its upstroke permits the over-center mechanism to fully toggle. As will also be appreciated, the over-center mechanism forms a bi-stable device that establishes the valve mechanism alternately in open and closed positions. With the actuator shaft  28  in the “on” position, normal operation providing reciprocating movement of the piston assembly  24  can continue.  
         [0023]     When the handle of the on/off switch mechanism  32  are moved to the “off” position, the insert  36  and the attached actuator shaft  28  are displaced to the offset position. As will be appreciated, when the piston assembly  24  moves in the upstroke excursion, the inner collar extension  48  cannot engage the shoulder  46  because the outer collar extension  50  will engage the top of the housing cover  12 A ahead of time. As a consequence, the valve mechanism  26  will not close to create the differential pressure within the housing  12  that is necessary to move the piston assembly  24  in the down stroke excursion portion of its reciprocating cycle. Also, although the over-center mechanism  42  will be partially moved, it will not fully toggle. Normal reciprocating movement operation of the piston assembly  24  will not continue, and liquid additive will no longer be injected into the primary fluid stream. Upon movement of the handle  40  to the “on” position, however, the inner collar extension  48  will engage the shoulder  46  on the actuator shaft  28 . The valve mechanism will close, and the over-center mechanism will complete toggling. The necessary differential pressure required for reciprocating movement of the piston assembly  24  will be re-established within housing  12 , and normal operation will resume.  
         [0024]      FIG. 3  is a perspective view of the upper and lower halves of the pump housing (housing cover  12 A and lower body  12 B) with a one-way-valve gasket  100  removeably secured between housing cover  12 A and lower body  12 B in a preferred embodiment;  FIG. 4  is a side cross-sectional view of the pump showing the assembly and isolated fluid mixing chamber;  FIG. 5  is another side cross-sectional view of the pump shown in  FIG. 4 ; and  FIGS. 6   a  through  6   f  are five different views of the one-way-valve gasket assembly in a preferred embodiment.  
         [0025]     Referring to  FIGS. 3 through 6 F, the lower body  12 B has a threaded collar  12 C for mating with the housing cover  12 A, which has corresponding threading around its bottom, inner circumference. The lower body  12 B has an outer cylinder wall  60  and an inner cylinder wall  62  which define a lower, exiting cylindrical channel/volume  68  (or “separate chamber”) that leads to the primary fluid exit  16 . The inner cylinder wall  62  contains the lower part of the piston  58  (shown in  FIG. 2 ) and encloses a variable-size lower cavity  64  (the volume of which is varied by the piston position) into which primary fluid enters from the primary fluid inlet  14 . After making its way through the piston assembly  24  shown in  FIG. 2 , primary fluid enters a variable-size upper cavity  66  (the volume of which is varied by the piston position). Upon the down-stroke of the piston assembly  24  (as shown in  FIG. 2 ), a metered volume of primary fluid within the upper cavity  66  and below the larger-diameter portion of the piston  52  is pushed downward through the one-way-valve gasket  100  and into the lower, exiting, post-gasket cylindrical channel/volume  68 , which then leads the primary fluid out through the pump exit  16 . Then, upon the up-stroke of the piston assembly  24  (as shown in  FIG. 2 ), the liquid additive injection pump  18  (shown in  FIG. 2 ) pushes a metered volume of fluid additive into either the post-gasket channel  68  or an external mixing chamber to combine with the exiting primary fluid, whichever is desired. For example, fluid additive can be routed from the liquid additive injection pump  18  (shown in  FIG. 2 ) through a port into the post-gasket channel  68 , thereby enabling the primary and additive fluids to mix within the pump without contacting the actual pumping elements. The one-way-valve gasket  100  prevents any fluid additive from flowing upstream into the upper part of the housing. Alternatively, a separate mixing chamber can be provided after the pump discharge  16 , and the metered volumes of primary fluid and fluid additive can be directed into such separate mixing chamber. Again, the one-way-valve gasket  100  prevents any fluid additive from flowing upstream into the upper part of the housing. In either case, the walls of the separate mixing chamber and/or the post-gasket channel can be lined or protected with corrosion-resistant or corrosion-retardant materials without the requirement to necessarily protect other portions or components of the pump. This is especially beneficial where use of corrosion-resistant or corrosion-retardant materials throughout the entire pump would be cost-prohibitive, mechanically-prohibitive, or otherwise not feasible.  
         [0026]      FIGS. 6A through 6F  show, in more detail, various views of the one-way-valve gasket  100  in a preferred embodiment. The one-way-valve gasket  100  comprises a generally-flat ring of any non-pervious, slightly-to-fairly pliable material, except for several curved, nipple-type valves  108  extending downward from the ring. The upper surface  102  and lower surface  104  are flat in the gasket&#39;s outer perimeter so that the gasket  100  can rest flush between the tiered (or flanged) bottom surface of the housing cover  12 A (shown  FIG. 1 ) and the tiered (or flanged) upper surface of the lower housing body  12  (shown in  FIG. 2 ). The nipple-type valves  108  extend downward from corresponding gaps  106  in the gasket ring  100 , through which primary fluid can pass downward but not upward when the valves point downward. In order for the nipple-type valves  108  to work properly, they must be made of a material whose thickness and flexibility are such that their angled ends  109  will open with typical piston-pumping fluid pressures but will also remain closed against fluid back-flows of foreseeable pressures. The gasket  100  also has several radial supporting fins  110  that extend from, and are perpendicular to, the gasket ring  100 . These supporting fins  110  fit snugly in a radial fashion across the cylindrical channel/volume  68  between the lower body&#39;s  12 B outer cylinder wall  60  and an inner cylinder wall  62  (as shown in  FIG. 3 ).  
         [0027]     Note, however, that the liquid additive injection pump having a fluid mixing chamber separated from the fluid-powered-motor components by a one-way-valve gasket of the present invention is subject to application and modification by those of ordinary skill in the art. Although the present invention has been described in terms of an exemplary embodiment, it is not limited to these embodiments and modifications. Alternative embodiments, modifications, and equivalents, which would still be encompassed by the invention, may be made by those of ordinary skill in the art, in light of the foregoing teachings. Therefore, the following claims are intended to cover any alternative embodiments, modifications, or equivalents which may be included within the spirit and scope of the invention defined by the claims.