Abstract:
A positive displacement material metering system is provided including a housing having an inlet port and an outlet port. A rotatable spindle is within the housing, the spindle provided with a chamber having a pair of openings. A piston is configured to reciprocate within the chamber. Each of the chamber openings is configured to receive liquid material when aligned with the inlet port and to dispense liquid material when aligned with the outlet port.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to the field of metering and dispensing equipment and, more particularly, to an improved positive displacement material metering system employing fewer components while increasing the precision at which the material is metered. 
       BACKGROUND OF THE INVENTION 
       [0002]    Metering and dispensing systems are generally employed to provide a measured flow of material from a material reservoir to a particular application. For example, many operations in the manufacture of an automobile require precisely metered materials such as the application of sealants to the automobile&#39;s body structure and in the molding of the material used in seating applications. Metering and dispensing devices ensure that a specified amount of material is delivered to the application each time the material is required. Metering and dispensing devices eliminate the guess work, human error, and waste associated with having to apply a precise amount of material to an application at each required cycle. 
         [0003]    Metering and dispensing devices are known in the art for metering and dispensing specified quantities of materials, such as sealants, adhesives, epoxies, and the like. Metering and dispensing devices are designed around the concept of a piston and cylinder. The piston is connected to a connecting rod that slides the piston fore and aft throughout the length of the cylinder much in the same way the piston works in an internal combustion engine. The connecting rod is then connected to a driveshaft that is operated by a motor. In metering and dispensing devices, when the piston reaches a specified location in the cylinder, material is allowed to fill through a cylinder inlet. When the cylinder has been filled, the piston is pushed by the connecting rod through the length of the cylinder, which in turn, forces the material out a cylinder outlet. The amount of material in the cylinder and dispersed during each cycle is a product of the cylinder height and the piston/cylinder diameter. The material can be metered either by changing the cylinder height or piston/cylinder diameter. 
         [0004]    While the prior art does offer an adequate means for metering and dispensing materials, they are however, not optimal. First, a number of prior art metering and dispensing systems require a number of components to operate. Specifically, the piston/connecting rod/driveshaft relationship involve a number of individual components for operation (valves, cylinder, piston, connecting rod, driveshaft, and various fasteners to connect the components). Second, it is also known in the art to combine two or more metering systems together to control the flow of two or more component materials so that they may be mixed together for a particular application. However, if multiple metering and dispensing systems are required for a particular operation, a number of valves, pistons, connecting rods, and driveshafts may be required. Because a number of components are required to operate the system, this may have a significant impact on the cost to the end user. Third, with pumps employing the piston variation having depressions to control the flow of material in the cylinder, some material metering precision may be lost because there may always be some unknown amount material left in the cylinder by the depression in the piston. Finally, in order to operate a number of systems together to ensure the precise amount of material is dispensed at the correct point in time for the application, the pistons will have to be connected to by the same driveshaft. This arrangement may make for a very large piece of equipment that may consume large amounts of valuable plant floor space. 
         [0005]    Therefore, a need exists for a positive displacement material metering system that can be utilized in compact areas and operates with fewer components while at the same time maintaining a precise delivery of material to an application on each and every required cycle. A need also exists for a material metering system that is easily expandable by simply adding cylinders or chambers and pistons as required by a particular application. The present invention satisfies these requirements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0006]    The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description: 
           [0007]      FIG. 1  is a perspective view of a metering device according to an embodiment of the present invention; 
           [0008]      FIG. 2  is a cross-sectional view of a metering device according to an embodiment of the present invention; 
           [0009]      FIG. 3  is a cross-sectional view of the metering device according to another embodiment of the present invention; 
           [0010]      FIG. 4  is a cross-sectional view of the metering device according to another embodiment of the present invention; 
           [0011]      FIGS. 5A ,  5 B,  5 C, and  5 D are cross-sectional views of the metering device shown at different positions during the cycle of operation according to an embodiment of the present invention; and 
           [0012]      FIGS. 6A ,  6 B,  6 C, and  6 D are cross-sectional views of the metering device shown at different positions during the cycle of operation according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0013]    The present embodiments provide a positive displacement metering device for use in applying a measured amount of resin, epoxy, glue, grease, or the like in a manufacturing environment. Referring to  FIG. 1 , a positive displacement material metering device  10  is presented. In an embodiment of the present invention, metering device  10  is shown connected to a motor  12  used to operate metering device  10  in a particular environment where required such as with automobile or airplane assembly operations, medical procedures, or the oil industry. Inlet hoses  11  and outlet hoses  13  are attached to metering device  10  to allow the flow of liquid material to and from metering device  10 . 
         [0014]    Referring now to  FIG. 2 , metering device  10  is illustrated. Metering device  10  includes a meter housing  14  and a spindle  16 . Housing  14  includes a main portion  18  and a capturing portion  20  for securing spindle  16  within housing  14 . Housing  14  further includes an interior surface  22  that provides a rotatable interface for an outer surface  24  of spindle  16  and allows spindle  16  to rotate freely within housing  14  about an axis A. Interior surface  22  covers both main and capturing portions  18  and  20  so that spindle  16  may rotate within both portions  18 ,  20 . Interior surface  22  includes bearings  26  that spindle  16  rotates upon and are used for reducing friction between outer surface  24  and interior surface  22 . Interior surface  22  further includes seals  28  that are used to ensure material does not escape housing  14  through interior surface/outer surface  24 / 26  interface. Bearings  26  may be manufactured from any metallic or polymeric material. Seals  28  may be manufactured from any polymeric material such as silicon. 
         [0015]    Main portion  18  of housing  14  further includes at least one material inlet port  30  and at least one material outlet port  32 . Both inlet port  30  and outlet port  32  pass from an outer surface  34  of housing  14  to interior surface  22 . Both inlet port  30  and outlet port  32  are cylinders having an axis B that is generally perpendicular to axis A. Both inlet port  30  and outlet port  23  may include couplings (not shown) at outer surface  34  that allow hoses or some other means to be attached to housing  14  so that material can be supplied to metering device  10  through inlet port  30  and dispensed from metering device  10  through outlet port  32 . 
         [0016]    Spindle  16  includes a metering chamber  36  that passes completely though spindle  16  and is centered about axis B when aligned with inlet port  30  and outlet port  32 . Chamber  36  is cylindrical in shape and captures a metering piston  38  that is allowed to freely rotate about axis B and freely slide throughout chamber  36  as spindle  16  is rotated about axis A. The diameter at a first end  40  of chamber  36  is smaller than the diameter of a main portion  41  of chamber  36 . The smaller diameter first end  40  prevents piston  38  from passing out of chamber  36  during operation of metering device  10 . The diameter of a second end  42  of chamber  36  remains the same diameter as main portion  41  of chamber  36  so that piston  38  can be easily loaded into chamber  36 . Piston  38  is captured within chamber  36  at second end  42  by a locking mechanism  44  that locks and seals against the walls of chamber  36 . Both first end  40  and locking mechanism  44  include holes  46  so that material can pass in and out of chamber  36 . Valves are not necessary to meter the flow of material to inlet port  30  or out of outlet port  32 . 
         [0017]    In an embodiment of the present invention shown in  FIG. 2 , metering device  10  is shown operating with a single metering chamber  36 , metering piston  38 , material inlet port  30 , and material outlet port  32  arrangement. In another embodiment of the invention illustrated in  FIG. 3  (where like elements have like reference numerals), the same spindle  16  may include multiple pistons  38  and chambers  36  with corresponding multiple inlet ports  30  and outlet ports  32  located on housing  14 . In this way, the number of metering devices  10  can be increased on a single spindle  16 , yet still only requires a single motor  12  for rotating of spindle  16 . Multiple metering devices  10  allows for the inline mixing or blending of different measured materials after being dispensed from metering device  10  and prior to arriving at the particular application. A precise amount of the blended materials will be delivered to the application at each cycling of metering device  10 . 
         [0018]    Metering device  10  is assembled by inserting metering piston  38  into metering chamber  36  of spindle  16 . Next, spindle  16  is inserted into main portion  18  so that material inlet port  30  and material outlet port  32  of housing  14  are aligned with chamber  36  in spindle  16 . Seals  28  are added to housing  14  and, finally, capturing portion  20  and bearings  26  are secured to main portion  18  to capture spindle  16 . An end  48  of spindle  16  can be connected to any conventional motor  12  so that spindle  16  can be rotated within housing  14  when metered material is required. 
         [0019]      FIG. 4  illustrates another embodiment of the present invention. In this particular embodiment, metering device  10 ′ includes a housing  14 ′ and spindle  16 ′ similar to housing  14  and spindle  16  disclosed as part of the embodiment shown in  FIG. 2 . Spindle  16 ′ will still rotate freely about axis A within housing  14  as in the original embodiment, however, housing  14 ′ now includes at least two material inlet ports  30 ′ and at least two material outlet ports  32 ′. Both inlet ports  30 ′ and outlet ports  32 ′ are cylinders having axes B and C respectively that are generally parallel to each other and generally perpendicular to axis A. Both inlet ports  30 ′ and outlet ports  32 ′ may include couplings (not shown) at an outer surface  34 ′ of housing  14 ′ that allow hoses or some other means to be attached to housing  14 ′ so that material can be supplied to metering device  10 ′ through inlet ports  30 ′ and dispensed from metering device  10 ′ through outlet ports  32 ′. 
         [0020]    Spindle  16 ′ includes a metering chamber  36 ′ having three segments. A first segment  50  and a third segment  52  are cylindrical in shape, centered about axis B and axis C respectively, and are generally perpendicular to axis A. A second segment  54  is also cylindrical in shape, however, second segment  54  is centered about axis A and generally perpendicular to both first and third segments  50  and  52 . First segment  50  includes a first hole  56  that corresponds to a first opening  58  in second segment  54 . Third segment  52  includes a second hole  60  that corresponds to a second opening  62  in second segment  54 . Segments  50 ,  52 , and  54  cooperatively form chamber  36 ′ and are connected such that material may flow from a first end  64  of first segment  50  through second segment  54  to a first end  66  of third segment  52  and in the reverse as well. 
         [0021]    A metering piston  38 ′ is included in spindle  16 ′ and captured in second segment  54  of metering chamber  36 ′. Piston  38 ′ is allowed to freely slide and rotate about axis A within chamber  36 ′. Piston  38 ′, however, is prevented from fully entering first and third segments  50  and  52  by stops  68  that have been machined into chamber  36 ′. It is undesirable to allow piston  38 ′ to fully enter into first and third segments  50  and  52  because a surface  70  of piston  38 ′ should be presented to the material entering chamber  36 ′ so that material can access a sufficient portion of piston  38 ′ surface area to force piston  38 ′ to move within chamber  36 ′. In this particular embodiment, spindle  16 ′ may be a two-piece assembly so that second segment  54  of chamber  36 ′ can be properly machined both in a first half  72  and in a second half  74  of chamber  36 ′. Piston  38 ′ can be loaded into one half of second segment  54  prior to securing two halves  72 ,  74  of spindle  16 ′ together and creating second segment  54  of chamber  36 ′. 
         [0022]    In this particular embodiment, metering device  10 ′ is assembled in the following manner. Piston  38 ′ is seated in second segment  54  of chamber  36 ′ in first half  72  of spindle  16 ′. Second half  74  of spindle  16 ′ is connected to first half  72  to create the entire second segment  54  and a complete spindle assembly  16 ′. Next spindle  16 ′ is inserted into main portion  18 ′ of housing  14 ′ so that material inlet ports  30 ′ and material outlet ports  32 ′ are aligned with corresponding holes  56 ,  60  of chamber  36 ′. Capturing portions  20 ′ are assembled to main portion  18 ′ to capture spindle  16 ′ within housing  14 ′. An end  48 ′ of spindle  16 ′ can be connected to any conventional motor  12  so that spindle  16 ′ can be rotated within housing  14 ′ when metered material is required. 
         [0023]    All the embodiments described above operate in the same fashion. The difference between the embodiments relate to the number and types of materials to be metered, whether those materials can be mixed or should remain separate, and at what cycle time are the materials required to be delivered to a particular application. As will be appreciated, the following is a description of the general operation of metering device  10 , keeping in mind that the same principles of operation apply to multiple metering devices  10  as well. 
         [0024]    Now referring to  FIGS. 5A ,  5 B,  5 C, and  5 D, operation of the embodiment illustrated in FIG. I will be described.  FIG. 5A  illustrated a pressurized material being presented to metering device  10  and introduced through material inlet port  30 . As shown in  FIG. 5B , pressurized material enters metering chamber  36  through inlet port  30  and forces metering piston  28  to opposite side of metering chamber  36 . When chamber  36  is filled with material, spindle  16  may be rotated by motor  12  so that end of chamber  36  filled with material may be aligned with material outlet port  30  and opposite end with piston  38  is aligned with inlet port  30  as illustrated in  FIG. 5C . As shown in  FIG. 5D , more pressurized material is introduced into inlet port  30  and begins to act against piston  38 , forcing piston  38  to the opposite end of chamber  36 . While pressurized material is filling void left by piston  38  at inlet port  30 , opposite end of piston  38  is forcing a measured amount of material out of outlet port  32  to be used in the appropriate application (See  FIG. 5D ). When chamber  36  is filled with pressurized material, piston  38  has completely dispensed pressurized material through outlet port  32  and spindle  16  can once again be cycled to repeat the process. 
         [0025]    Now referring to  FIGS. 6A ,  6 B,  6 C, and  6 D, operation of another embodiment of the invention illustrated in  FIG. 1 . will be described. In an embodiment that discloses metering chamber  10 ′ with multiple segments  50 ,  52 , and  54  within spindle  16 ′, the same principle holds for metering and dispensing pressurized materials as was disclosed for a single segment chamber  36 . In another embodiment of the present invention, two material inlets port  30 ′ and two material outlet ports  32  have access to the same chamber  36 ′. However, only one piston  38 ′ is required for dispensing a measured amount of material, thereby reducing the number of unique components for operation. This embodiment of the invention may be employed when two different types of material are required in an application, yet they may or may not require mixing. 
         [0026]      FIG. 6A  illustrates a pressurized material being presented to metering device  10 ′ and introduced through a first material inlet port  30 ′. As shown in  FIG. 6B , pressurized material from a first source enters metering chamber  36 ′ through first inlet port  30 ′ and forces metering piston  38 ′ to opposite side of second segment  54  of chamber  36 ′. When first and second segments  50  and  54  of chamber  36 ′ are filled with material, spindle  16 ′ may be rotated by motor  12  so that end of chamber  36 ′ filled with material is aligned with a first material outlet port  32 ′ and third segment  52  is aligned with second material inlet port  30 ′ as illustrated in  FIG. 5C . As shown in  FIG. 5D , pressurized material from a second source is introduced into third segment  52  through second inlet port  30 ′ and begins to act against piston  38 ′ in second segment  54 , forcing piston  38 ′ to the opposite end of second segment  54  of chamber  36 ′. While pressurized material is filling void left by piston  38 ′ at second inlet port  30 ′, opposite end of piston  38 ′ is forcing a measured amount of material out of first outlet port  32 ′ to be used in the appropriate application (See  FIG. 5D ). When third and second segments  52  and  54  of chamber  36 ′ are filled with pressurized material, piston  38 ′ has completely dispensed a measured amount of pressurized material through second outlet port  32 ′ and spindle  16 ′ can once again be cycled to align third segment  52  with a second outlet port  32 ′ and first segment  50  with first inlet port  30 ′ to repeat the process. 
         [0027]    As discussed above, spindles  16 ,  16 ′ may include multiple chambers  36 ,  36 ′ for dispensing metered material and can be located at different angles relative to each other within spindle  16 ,  16 ′. The number of chambers  36 ,  36 ′ required and the angle of location relative to each other is completely dependant on the operation or application in use. Also, the amount of metered material can be varied simply by modifying the height of piston  38 ,  38 ′ and/or modifying the bore diameter of chamber  36 ,  36 ′. 
         [0028]    Metering device  10 ,  10 ′ may be manufactured from any number and combination of materials such as metals, polymers, or ceramics. For example, housing  14 ,  14 ′, spindle  16 ,  16 ′ and piston  38 ,  38 ′ may be manufactured out of a ceramic material if the required metering of material is highly precise because ceramic components may be manufactured with tighter tolerances versus other materials. However, if durability of metering device  10 ,  10 ′ is a concern, then less brittle metallic materials such as aluminum or steel may be better suited for the particular application. 
         [0029]    The present invention has been particularly shown and described with reference to the foregoing embodiments, which are merely illustrative of the best modes for carrying out the invention. It should be understood by those skilled in the art that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention without departing from the spirit and scope of the invention as defined in the following claims. It is intended that the following claims define the scope of the invention and that the method and apparatus within the scope of these claims and their equivalents be covered thereby. This description of the invention should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. Moreover, the foregoing embodiments are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application.