Abstract:
An improved piston-type pump ( 10 ) is provided which includes an upstanding, dual-hopper product feeding assembly ( 22 ) which increases pump efficiency and lessens required pump floor space. The assembly ( 22 ) includes a lower vacuum hopper ( 42 ) including a fixed section ( 46 ) and a shiftable upper section ( 48 ) having a top ( 52 ); an upper atmospheric pressure hopper ( 44 ) is permanently secured to top ( 52 ) and is shiftable with section ( 48 ). A passageway ( 54 ) is provided between the hoppers ( 44 ) and ( 42 ). A flow-control valve unit ( 45 ) is located adjacent the passageway ( 54 ).

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is broadly concerned with improved piston pump units equipped with a dual-hopper product feeding assembly which improves pump efficiency and lessens the required floor space for the pump. More particularly, the invention is concerned with such piston pumps as well as the dual-hopper assemblies used with the pumps and related retrofit assemblies which can be mounted on existing piston pumps. In preferred forms, the dual-hopper assemblies include a lower vacuum hopper with a permanently interconnected and substantially coaxially mounted upper atmospheric pressure hopper; a passageway is provided between the upper and lower hoppers, together with the selectively operable valve unit.  
         [0003]     2. Description of the Prior Art  
         [0004]     Piston-type pumps have long been available for the processing of foods and other valuable products. Piston pumps are known to be especially gentle with such products, and therefore are favored over vane or screw pumps. For example, Marlen Research Corporation has commercialized dual-piston pumps which have outstanding efficiencies while avoiding product degradation. Many of these pumps are of the vacuum variety, i.e., the pumping is conducted under subatmospheric conditions in order to deaerate the product during processing. See, e.g., U.S. Pat. Nos. 5,479,847 and 5,474,101.  
         [0005]     Piston-type vacuum pumps include an upstanding, permanently attached vacuum hopper which receives product and delivers it to a lower pumping chamber. Generally speaking, in order to obtain commercial-scale throughputs, it is necessary to also provide an auxiliary atmospheric pressure hopper next to the pump. An elongated tubular conduit extends between the bottom of the auxiliary hopper and the vacuum hopper, and serves to convey product from the auxiliary to the vacuum hopper.  
         [0006]     This conventional approach presents a number of practical problems. First of all, the existence of the separate atmospheric hopper takes up valuable floor space in a processing plant. In many instances floor space is more valuable than the space above a pump, i.e., many plants are constructed with high ceilings allowing fabrication of upper catwalks or dumping devices, whereas floor space is at a premium.  
         [0007]     Additionally, use of a conduit between the auxiliary and vacuum hoppers often requires that the conduit be oriented at a substantial angle. This makes it more difficult to convey viscous materials owing to frictional forces developed within the conduit. Moreover, connection joints are required at the ends of the conduit, and these can be difficult to precisely align under working plant conditions. Cleanout of the pipes is also a problem, especially when the pipes are under load.  
         [0008]     There is accordingly a real and unsatisfied need in the art for improved dual-hopper product feeder system for use with piston-type pumps which eliminate the need for separate auxiliary hoppers and conduits between hoppers.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention overcomes the problems outlined above, and provides pumping apparatus in the form of a piston-type pump including a chamber with a product inlet and a pair of outlets, where the chamber adapted to receive product to be pumped. A pair of reciprocal piston assemblies are located within the chamber serve to successively deliver charges of product to the chamber outlets. A dual-hopper assembly is disposed above the chamber for product delivery purposes. This dual-hopper assembly includes a lower vacuum hopper having an upstanding hopper body and a closure section with a passageway therethrough. An upper atmospheric pressure hopper is disposed over and operably coupled with the lower vacuum hopper section so as to establish communication between the upper and lower hoppers. A selectively operable valve unit is also located adjacent the passageway and is operable in alternate positions thereof to open and close the passageway.  
         [0010]     In preferred forms, the lower hopper section is hingedly mounted relative to the lower hopper body for opening and closing of the section as well as the upper hopper. The upper and lower hoppers are normally of generally frustoconical configuration and are substantially concentrically arranged.  
         [0011]     A product feeding assembly can also be provided as a retrofit for existing, conventional system-pumps. Advantageously, such a feeding assembly would include a lower vacuum hopper section in the form of a hopper wall with an apertured top, together with a permanently fixed upper atmospheric hopper secured to the section top. A valve unit also forms a part of the product feeding assembly and includes a valve plate disposed adjacent the communicating passageway between the upper hopper and the lower hopper section. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a side view of a piston-type pump equipped with the dual hopper assembly of the invention, wherein the assembly is shown in its operative position in bold lines, and in its opened position in phantom;  
         [0013]      FIG. 2  is a plan view of the pump and dual hopper assembly of the invention;  
         [0014]      FIG. 3  is a vertical sectional view taken along line  3 - 3  of  FIG. 2  and depicting the internal construction of the dual hopper assembly;  
         [0015]      FIG. 4  is a bottom view of the dual hopper assembly;  
         [0016]      FIG. 5  is a fragmentary top view in partial section and illustrating the construction of preferred piston pump of the invention; and  
         [0017]      FIG. 6  is a plan view illustrating a conventional prior art hopper and pump unit with a separate atmospheric pressure hopper and a conduit between the separate hopper and the pump. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]     As described previously, the conventional practice with piston pumps such as the pump  10  of  FIG. 6  is to arrange a product feeding assembly  12  made up of a vacuum hopper  14  directly coupled to the pump  10  together with a separate, open-top atmospheric pressure hopper  16  astride the pump  10 . This necessitates provision of an elongated tubular conduit  18  between the base of hopper  16  and an inlet to the vacuum hopper  14 . A valve assembly  20  such as that depicted in U.S. Pat. No. 5,102,094 serves to control flow of product from the atmospheric pressure hopper  16  to vacuum hopper  14 . As can be readily seen from the  FIG. 6  illustration, the conventional approach inherently has a large footprint and takes up valuable plant floor space. Additionally, the conduit  18 , typically being inclined, can make it difficult to transfer product between the hoppers, especially stiff and highly viscous materials.  
         [0019]     The present invention is designed to overcome the deficiencies of this conventional approach, without sacrificing product throughput or quality. Referring to  FIGS. 1-3 , a piston pump  10  is equipped with a dual hopper product feeding assembly  22  which is fully supported by the pump body and entirely eliminates the need for a separate hopper and related hardware.  
         [0020]     Turning next to  FIG. 5 , it will be seen that the preferred vacuum pump  10  includes a lower pump body  24  having a product chamber  26  having an upper inlet and a pair of side-by-side, laterally spaced apart outlet openings  28  and  30 . A somewhat U-shaped valve  32  is operably coupled to the body  24  in communication with the openings  28 ,  30 . A pair of sleeve and piston assemblies  34  and  36  are located within the chamber  26  for delivering successive charges of product to the outlet openings  28  and  30 . Each of the assemblies  34 ,  36  includes an axially shiftable sleeve  38  as well as a cooperating, internal, axially shiftable piston  40 . The sleeves  38  and pistons  40  are operated in a timed relationship so as to deliver the product charges to the pump outlet. This type of dual-piston pump is fully described in U.S. Pat. Nos. 5,479,847 and 5,474,101, which are incorporated by reference herein.  
         [0021]     The dual hopper product feeding assembly  22  broadly includes a lower vacuum hopper  42  together with an upper, open-top, atmospheric pressure hopper  44  and a valve assembly  45 . As shown, the hoppers  42 ,  44  are both generally frustoconical in configuration and are substantially concentrically arranged, while the valve assembly  45  operates between the hoppers  42  and  44 .  
         [0022]     Lower vacuum hopper  42  in preferred forms is made up of a lower, upstanding hopper body  46  which is permanently affixed to the top of pump body  24  and defines with the latter the product inlet for pump chamber  26 . Additionally, the lower vacuum hopper  42  has an upper section  48  which cooperates with body  46  to form the complete lower vacuum hopper. The section  48  is made up of an upper frustoconical wall section  50  having a bottom wall  51 , with the section  50  surmounted by an arcuate, dome-like top  52 . The top  52  has a central passageway  54  which establishes communication between hopper  44  and the section  48  (and thus the lower vacuum hopper  42 ). An upstanding tubular vacuum coupler  56  is also supported by top  52  and permits attachment of a vacuum pump (not shown) for maintaining vacuum conditions within hopper  42  as desired. A second tubular coupler  58  is also supported by top  52  and permits use of a gauge  60  and photoelectric eye  62  which are used to monitor operation of the assembly  22  and pump  10 . As best seen in  FIGS. 3 and 4 , an arcuate, depending deflector wall  64  is secured to the underside of top  52  in proximity to passageway  54 .  
         [0023]     The upper hopper  44  includes a frustoconical sidewall  66  defining an open top  68 . The lower end of sidewall  66  includes an arcuate section  70  which extends below the top  52  (see  FIGS. 3 and 4 ).  
         [0024]     The valve assembly  45  includes a valve plate  72  which is designed for selective opening and closing of passageway  54 . The plate  72  is supported by an elongated, upstanding rod  74  shiftable within a housing  76 . The housing  76  also supports a drive  78  coupled with the rod  74  for reciprocation thereof. The drive  78  may be in the form of a piston and cylinder assembly or an electric or hydraulic motor.  
         [0025]     The section  48  and upper hopper  44  are hingedly mounted to the pump  10  by means of support  80 . This allows the section  48  and hopper  44  to be shifted between an operative position illustrated in bold lines in  FIG. 1 , and an open clean-out or accessed position shown in phantom. Of course, given that the hopper  44  is permanently secured to the section  48 , these components pivot in unison between the use and access positions, all as shown in  FIG. 1 .  
         [0026]     During use of the pump  10  equipped with the assembly  22 , the product to be pumped is first delivered to open-top upper hopper  44 . This may be done through a conventional bucket loader or by manually dumping product into the hopper. As pumping proceeds, the valve assembly  45  is periodically operated in order to open passageway  54 , allowing product to pass directly into lower vacuum hopper  42 . Once the hopper  42  is full, the valve assembly  45  is actuated to close plate  72  against the defining walls of passageway  54 , so that appropriate vacuum conditions can again be established within lower chamber  42 . Product within chamber  42  is delivered to chamber  26  where the piston and sleeve assemblies  34 ,  36  are operated to deliver charges of product to the outlet valve  32 .  
         [0027]     The invention may be practiced through production of complete pumps having the dual-hopper product feeding assembly  22 . Alternately, a retrofit assembly can be fabricated, made up of the section  48 , hopper  44  and valve assembly  45 . This retrofit unit can be attached to an existing pump in lieu of the standard upper vacuum hopper section originally provided with the pump.