Abstract:
A hopper loader having a hopper connected to a vacuum source for applying a vacuum to the hopper to convey material into the hopper through a material inlet. A material separator is disposed between the material inlet and the vacuum source for filtering the material. A material discharge assembly is connected to the hopper and disposed for controlling downwardly gravity flow of the material from the hopper, the material discharge assembly having a material outlet configured to be opened and closed to control the discharge of material from the hopper. A vacuum detector is disposed between the material separator and the vacuum source. A vacuum activated control operatively connected to the vacuum detector and configured to turn off the vacuum source in response to a signal from the vacuum detector.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) of the earlier filing date of U.S. Provisional Patent Application No. 62/115,219 filed on Feb. 12, 2015, the disclosure of which is incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    This application discloses an invention which is related, generally and in various embodiments to vacuum loading systems. 
         [0003]    In the plastic industry it is common practice to transport material such as plastic pellets from a source of material such as a storage bin to the hopper of a hopper loader by applying a vacuum to the hopper with a vacuum generator. When an appropriate amount of material has been received in the hopper of the hopper loader, the material conveying is discontinued by discontinuing the applied vacuum and thereby permitting the material in the hopper to be gravitationally discharged through a material outlet of the hopper loader in communication with the hopper. Presently, the length of time to convey is determined by either setting a load timer on a control or using a material sensor to determine when the hopper is full. The problem with setting the timer is that 1) it&#39;s a manual function that is empirically determined; and 2) changes to the process require adjustment. The problem with using a sensor is that 1) the sensor may be deceived by material clinging to it due to static electricity; 2) the sensor must be in contact with the material or be in “line of sight”; and 3) may be eroded due to contact with the material. The invention seeks to solve the problems associated with determining the proper load time for a hopper loader that are encountered by empirical and material sensing methods. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    For the present invention to be clearly understood and readily practiced, the present invention will be described in conjunction with the following figures, wherein like reference characters designate the same or similar elements, which figures is incorporated into and constitutes a part of the specification. 
           [0005]      FIGS. 1-3  show perspective and two side views, respectively, of a vacuum loading system according to a vertical axis embodiment of the invention. 
           [0006]      FIG. 4 a    shows an exploded side view of a vacuum loading system according to a vertical axis embodiment of the invention having it local vacuum source. 
           [0007]      FIG. 4 b    shows an exploded side view of a vacuum loading system according to a vertical axis embodiment of the invention having a remote vacuum source. 
           [0008]      FIG. 5 a    shows an exploded side view of a vacuum loading system according to a tilted axis embodiment of the invention having a local vacuum source. 
           [0009]      FIG. 5 b    shows exploded side view of a vacuum loading system according to a tilted axis embodiment of the invention having a remote vacuum source. 
           [0010]      FIG. 6  is a flow chart showing the sequence of operation of the vacuum loading system according to embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the invention, while eliminating, for purposes of clarity, other elements that may be well known. Those of ordinary skill in the art will recognize that other elements are desirable and/or required in order to implement the invention. However, because such elements are known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. The detailed description will be provided herein below with reference to the attached drawings. 
         [0012]    For purposes of the description hereinafter, the terms “upper”, “lower”, “vertical”, “tilted”, “top”, “bottom”, and derivatives thereof shall relate to the invention, as it is oriented in the drawings. However, it is to be understood that the invention may assume various alternative configurations except where expressly specified to the contrary. It is also to be understood that the specific elements illustrated in the drawings and described in the following specification are simply exemplary embodiments of the invention. Therefore, specific dimensions, orientations and other physical characteristics related to the embodiments disclosed herein are not to be considered limiting. 
         [0013]    Referring to  FIGS. 1-4   a,  in one embodiment of the invention, hopper loader  10   a  comprises a hopper  12  connected a vacuum motor or source  14 . In this embodiment, vacuum source  14  is a local vacuum source integral to hopper loader  10   a,  and hopper loader  10   a  has a vertical axis. In the embodiments shown in  FIGS. 4 b    to  5   b,  the vacuum source may be remote and/or the hopper loader may have a tilted axis. 
         [0014]    Referring to  FIG. 4   a,  hopper loader  10   a  has an air material separator  16  such as a filter above hopper  12  and below vacuum source  14  such that the material separator  16  is positioned between the hopper  12  and the vacuum source  14 . Material separator  16  filters the material to keep dust and other particulate matter, traveling with the material from entering the suction intake of the vacuum source  14 . Vacuum source  14  creates a vacuum or suction in hopper  12  to draw material into hopper  12  through a material inlet  17  from a material source (not shown) which may be a source of material such as plastic beads, plastic resins, blended resins, powders, re-grind waste materials, cereal or candy. Hopper  12  has a cylindrical upper section and a frusto-conical lower section which terminates in a material discharge assembly  18  ( FIG. 4 a   ) at the base of hopper  12 . Material inlet  17  may be connected to the material source by piping (not shown). 
         [0015]    Material discharge assembly  18  is located for downward, gravity flow of material from hopper  12 . Material discharge assembly  18  has a material outlet  20  which is opened and closed to control the discharge of material from hopper  12 . The material discharge assembly  18  includes, for example, a valve plate  22  pivotally carried by a shaft  24  and is moveable between a closed position covering material outlet  20  and an open position away from material outlet  20 . The valve plate  22  is biased to the closed position by, for example, a counter weight  26 . A material demand sensor  28  is disposed at material discharge assembly  18 . Material demand sensor  28  determines whether material is needed. For example, the counterweight  26  is a magnet and the demand sensor  28  is a reed switch that senses the presence of the magnet. In the position shown in  FIG. 4   a,  the hopper  12  is empty and the magnet counterweight  26  is not near the demand sensor  28 , so that causes a demand, vacuum source  14  comes on and hopper loader  10   a  begins filling with material. After the vacuum source  14  stops, the material in hopper loader  10   a  forces the valve plate  22  open to permit the material to escape. If the bin (not shown) below hopper loader  10   a  is sufficiently full that the valve plate  20  remains open due to the material not being able to fully discharge from the hopper  12 , then the magnet counterweight  26  is sensed by the demand sensor  28  and vacuum source  14  will not come on. When the material level in the bin below hopper loader  10   a  drops low enough that all the material in the hopper loader  10   a  is emptied and not holding valve plate  22  open, valve plate  22  will close and move magnet counterweight  26  sufficiently far from demand sensor  28  that the sensor no longer can detect its presence and sense whether the material outlet  20  of the material discharge assembly  18  is closed. This produces a signal that will permit the vacuum source  14  to turn on and begin loading again. Alternatively, demand sensor  28  may be a capacitive proximity device, inductive proximity device, optical sensing device, or a number of other devices capable of sensing an object in close proximity. 
         [0016]    A vacuum detector  30  is disposed between air material separator  16  and the suction intake of the vacuum source  14 . Vacuum detector  30  senses the vacuum produced by the vacuum source  14  in the hopper  12 . When hopper  12  is full of material or has a maximum amount of material, an increase in vacuum is sensed by vacuum detector  30 . A minimum increase is required which varies based on vacuum source  14  and hopper  12 . When the vacuum first begins, a higher than normal vacuum is sensed by vacuum detector  30 , then the vacuum level decreases to a steady state level determined by vacuum source  14 , distance material is being conveyed, type of material, and other variables in the system. After this vacuum source  14  will remain close to the steady state value until the hopper  12  is full. At this time, vacuum source  14  will increase sharply in a short period of time and it is this step change in vacuum that is used to determine that hopper  12  is full. Vacuum detector  30  may be a vacuum sensor or a vacuum actuated switch. A vacuum sensor has an analog output indicating the vacuum level of material in hopper  12  between a minimum and maximum. A vacuum actuated switch has an output that indicates the vacuum level is either above or below a predetermined level. How high above or below the predetermined level is not measureable with a vacuum actuated switch, but is with a vacuum sensor. The vacuum detector  30  is only monitored during the time that vacuum source  14  is on. When the vacuum is on and the step function is detected by the vacuum sensor, then the vacuum source  14  is turned off. Discharge assembly  18  is controlled by gravity. 
         [0017]    An automated vacuum activated control  32  is operatively connected to the vacuum detector  30  to receive a signal when the vacuum detector  30  signals the hopper  12  of the hopper loader  10   a  is full or has reached a maximum amount. The vacuum activated control  32  controls the operation or the vacuum source  14  and the opening and closing of the material discharge assembly  18  based on the signal. 
         [0018]    The sequence of operation of hopper loader  10   a  is shown in the flow chart illustrated in  FIG. 6 . 
         [0019]    In step  102 , power is applied to the hopper loader  10   a.  This power is the power needed to operate the device. It is, for example, 110 VAC, 220 VAC, 24 VAC, or 24 VDC, however other voltages could be used. 
         [0020]    In step  104 , if the material demand sensor  28  determines that material is needed vacuum source  14  is turned on (step  106 ). 
         [0021]    The vacuum source  14  will cause material to be conveyed into the hopper  12  from a material source (not shown) through material inlet  17 . The vacuum source  14  will stay on until the vacuum level sensed by vacuum detector  30  exceeds a predetermined level (step  108 ) or a maximum load time (step  110 ) is exceeded. 
         [0022]    Once the maximum load time is exceeded (step  110 ) or the vacuum level exceeds the maximum predetermined level (step  108 ), vacuum activated control  32  will turn off vacuum source  14  (step  112 ). 
         [0023]    After the vacuum source  14  is turned off (step  112 ), vacuum activated control  32  causes a time delay (step  116 ) to allow the material in the hopper  12  to discharge and then the vacuum activated control  32  returns to step  102 . The typical time delay used in the control to empty hopper  12  is 5 seconds. This time is to ensure that the vacuum source  14  has completely stopped and given gravity a chance to pull valve plate  22  open, however if the bin (not shown) below hopper loader  10   a  is full it may actually take several minutes or longer for hopper  12  to become empty. 
         [0024]    This differs from existing technology as it is independent of time and does not rely on sensing the presence of material. This results in a system that will adapt as variations in external parameters take place without the intervention of an operator. This system also does not suffer problems associated with sensing the material, such as “false full” signals created by material clinging to the sensor due to static electricity, sensor circuitry drift causing the sensor to no longer operate properly, sensor adjustments necessary due to variations in the material being sensed, abrasion of sensors in direct contact with material, and variations in opacity when using optical sensors. 
         [0025]    Alternative embodiments are shown in  FIGS. 4 b    to  5   b.  Referring to  FIG. 4   b,  an embodiment is shown of a central vacuum hopper loader  10   b  having a vertical axis and a remote vacuum source  114 . Referring to  FIG. 5   a,  an embodiment is shown of a vacuum hopper loader  100   a  having a vertical axis and an integral local vacuum source  14 . Referring to  FIG. 5   b,  an embodiment is shown of a central vacuum hopper loader  100   b  having a tilted axis and a remote vacuum source  114 . The tilted hopper loader  100   a,    100   b  typically provides easier access to the interior of the hopper loader for cleaning. The tilted hopper loader  100   a,    100   b  is tilted at a fixed angle which allows easier access to the interiors of the hopper loader  100   a,    100   b  than the vertical axis hopper loader  10   a,    10   b.    FIGS. 5 a  and 5 b    show valve plate  22  in an open position while  FIGS. 4 a  and 4 b    show valve plate  22  in a closed position. Other than the orientation of the axes of the hopper loaders, and the type of vacuum source, the components and operation of the hopper loaders are the same and like components, therefore, have been identified with like reference numerals. 
         [0026]    Although the invention has been described in terms of particular embodiments in an application, one of ordinary skill in the art, in light of the teachings herein, can generate additional embodiments and modifications without departing from the spirit of, or exceeding the scope of, the claimed invention. Accordingly, it is understood that the drawings and the descriptions herein are proffered by way of example only to facilitate comprehension of the invention and should not be construed to limit the scope thereof.