Abstract:
A flowable material level sensor for use in a material containment structure which closes or activates a switch when the flowable material in the containment structure reaches a predetermined level. The sensor includes an elongated rod or wand which extends downwardly from a sensor housing positioned in the containment structure. The sensor includes an actuator assembly which converts angular or lateral movement of the rod into upward longitudinal movement of an actuator element therein which closes the switch when the level of material in the containment structure has reached the predetermined level. The closure of the switch is communicated to a monitoring station remote from the containment structure.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a material level sensor and more particularly to a material level sensor of the tilt type for sensing the level of flowable materials such as cement, grain or coal in a containment structure such as an elevator, bin, granary, silo, etc. 
     2. Description of the Related Art 
     Many types of material level sensors or monitors have been previously provided which sense the level of flowable or particulate material such as grain, cement, coal, etc. in a containment structure. Many of the prior art systems employ an electric switch which is closed upon the level of material in the containment structure reaching a predetermined level. One of the problems of the prior art systems is that the actuation of the sensor switch may create a spark which may cause an explosion of the dust from the grain, cement, coal, etc. Further, a problem with the prior art level sensors is that they are unduly complicated and expensive to manufacture and install. A further disadvantage of some of the prior art level sensors is that they employ a switch having hazardous mercury therein. 
     SUMMARY OF THE INVENTION 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key aspects or essential aspects of the claimed subject matter. Moreover, this Summary is not intended for use as an aid in determining the scope of the claimed subject matter. 
     A material level sensor is disclosed for sensing the level of a flowable material such as cement, grain or coal, etc. in a containment structure such as an elevator, bin, granary, silo, etc. The flowable material level sensor includes a vertically disposed cylindrical and cup-like shaped lower housing having an open upper end, a closed lower end, an inner surface, an outer surface and an internal compartment. The lower housing has external threads formed in the outer surface thereof at the open upper end thereof. An inverted cup-shaped cover is selectively threadably secured to the external threads at the upper end of the lower housing. The lower housing has at least one hollow, first tubular member or stub extending horizontally laterally outwardly from the internal compartment thereof which is configured to have a cable or wires extending therethrough. The lower end of the lower housing has a centrally located circular opening formed therein. The lower housing has a hollow second tubular member having upper and lower ends which extends downwardly from the lower end of the lower housing with the interior of the second tubular member being in communication with the circular opening in the lower end of the lower housing. A cylindrical bushing, having upper and lower ends, is positioned in the circular opening in the lower end of the lower housing. The second tubular member may have external threads formed therein at the lower end thereof. The second tubular member also has internal threads formed therein at the lower end thereof. 
     The level sensor also includes a vertically disposed cylindrical actuator assembly having upper and lower ends. The actuator assembly includes a vertically disposed and cylindrical upper housing member having upper and lower ends. The upper housing member of the actuator assembly has a generally cylindrical lower bore extending upwardly thereinto from the lower end thereof. The upper housing member of the actuator assembly also has a cylindrical upper bore extending downwardly thereinto which communicates with the cylindrical lower bore thereof. The cylindrical upper bore has a diameter less than the cylindrical lower bore so that a shoulder is formed at the juncture of the cylindrical upper and lower bores of the upper housing member of the actuator assembly. The upper housing member of the actuator assembly has external threads at the lower end thereof so that the upper housing member may be threadably secured to the internal threads of the second tubular member. 
     The actuator assembly also includes a vertically disposed cylindrical lower housing member having upper and lower ends. The upper end of the lower housing member of the actuator assembly is selectively secured to the lower end of the upper housing member of the actuator assembly. The lower housing member of the actuator assembly has a semi-spherical upper bore extending downwardly thereinto. The upper end of the upper bore of the lower housing member of the actuator assembly has the same diameter as the lower end of the lower bore of the upper housing member of the actuator assembly and is in communication therewith. The upper bore of the lower housing member of the actuator assembly is semi-spherically configured to provide a ball member receiving socket. The lower housing member of the actuator assembly has a tapered lower bore extending upwardly thereinto which communicates with the upper bore of the lower housing. 
     The actuator assembly also includes a lower actuator element with the lower actuator element including an elongated and cylindrical shaft having upper and lower ends and a generally semi-spherical ball member secured to the upper end of the cylindrical shaft thereof with the ball member having an upper end which has a semi-spherical socket formed therein. 
     The semi-spherical ball member of the lower actuator element is movably positioned in the arcuate ball member receiving socket in the upper bore of the lower housing member of the actuator assembly with the cylindrical shaft of the lower actuator element extending downwardly through the lower bore of the lower housing member so that the lower end of the shaft of the lower actuator element is disposed below the lower end of the actuator assembly. 
     The actuator assembly also includes an upper actuator element. The upper actuator element includes an elongated and cylindrical shaft having upper and lower ends and a generally semi-spherical ball member secured to the lower end of the shaft thereof with the shaft thereof extending upwardly through the lower and upper bores of the upper housing member of the actuator assembly and with the ball member thereof being movably received by the semi-spherical socket in the upper end of the ball member of the lower actuator element. The upper actuator element is vertically movable from a lower position to an upper position. A spring is associated with the upper actuator element to yieldably urge the upper actuator element downwardly so that the ball member on the upper actuator element is urged into engagement with the semi-spherical socket formed in the upper end of the semi-spherical ball member on the upper end of the cylindrical shaft of the lower actuator element. 
     A vertically disposed rod has its upper end secured to the lower end of the lower actuator element and extends downwardly therefrom. When the level of material in the containment structure reaches the lower end of the rod and moves the same laterally, the lower actuator element is pivotally or angularly moved which causes the upper actuator element to move upwardly. 
     A normally open actuator switch is mounted in the lower housing directly above the upper end of the shaft of the upper actuator element. When the shaft of the upper actuator element is moved upwardly upon the rod being moved laterally by the material, the shaft of the upper actuator element closes the actuator switch. The closure of the actuator switch either alerts an operator of the material level and/or deactivates the conveyor supplying material to the containment structure. 
     A principal object of the invention is to provide an improved material level sensor of the tilt type. 
     A further object of the invention is to provide a novel tilt switch which converts angular movement to linear movement thereby closing a switch to shut down a conveyor or to alert an operator of the closure of the switch. 
     A further object of the invention is to provide a device of the type described which does not use mercury in the switch thereof. 
     A further object of the invention is to provide a device of the type described which is simple and unique in design. 
     A further object of the invention is to provide a device of the type described which easily meets hazardous location certification requirements. 
     A further object of the invention is to provide a device of the type described which is inexpensive to produce and easily mounted in a containment structure. 
     These and other objects will be apparent to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. 
         FIG. 1  is a cross-sectional view of a material containment structure having the level sensor of this invention installed therein; 
         FIG. 2  is a perspective view of the level sensor of this invention; 
         FIG. 3  is a partial perspective view of the level sensor of this invention; 
         FIG. 4  is a partial exploded perspective view of the level sensor of this invention; 
         FIG. 5  is a partial exploded perspective view of the level sensor of this invention; 
         FIG. 6  is an upper perspective view of the lower housing member of the actuator assembly of the level sensor of this invention; 
         FIG. 7  is a lower perspective view of the lower housing member of the actuator assembly of the level sensor of this invention; 
         FIG. 8  is a perspective view of the upper and lower actuator elements of the level sensor of this invention; 
         FIG. 9  is a partial sectional view of the level sensor of this invention; 
         FIG. 10  is a partial sectional view of the level sensor of this invention; and 
         FIG. 11  is a partial sectional view similar to  FIG. 10  but which illustrates the lower actuator element having been angularly moved thereby causing upward movement of the upper actuator element thereby closing the switch of the level sensor. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Embodiments are described more fully below with reference to the accompanying figures, which form a part hereof and show, by way of illustration, specific exemplary embodiments. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the invention. However, embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. The following detailed description is, therefore, not to be taken in a limiting sense in that the scope of the present invention is defined only by the appended claims. 
     The numeral  10  refers to the material level sensor of this invention which is designed to be used in a containment structure  12  such as an elevator, bin, granary, silo, etc. to sense the level of a particular or flowable material  14  therein such as cement, grain, coal, etc. Sensor  10  includes a vertically disposed cylindrical and cup-shaped lower housing  16 , having an open upper end  18 , a closed lower end  20 , an inner surface  22 , an outer surface  24 , and an internal compartment  26 . The lower housing  16  has external threads  28  formed in the outer surface  24  at the open upper end  18 . 
     An inverted cup-shaped cover  30  has internal threads  32  formed in the inside surface thereof at the lower end thereof which are adapted to be threadably secured to the external threads  28  on lower housing  16 . An O-ring  34  embraces the lower end of external threads  28 . 
     A pair of tubular members or pipe stubs  36  and  38  extend laterally outwardly from internal compartment  26  of lower housing  16  for the passage of wires or cables extending therethrough. In some cases, only a single tubular member  36  will be required. The lower end  20  of lower housing  16  has a centrally positioned opening  40  formed therein. Lower housing  16  has a tubular member  42  extending downwardly from lower end  20  and which has an inside diameter which is greater than the diameter of opening  40  to define a shoulder  44  therebetween. Tubular member  42  has external threads  46  formed in the outer surface thereof at the lower end thereof and has internal threads  48  formed in the inner surface thereof. As seen, a bushing  50  is positioned in opening  40  and has a vertically disposed bore  52  extending therethrough. 
     The numeral  54  refers to the actuator assembly of this invention which includes a cylindrical upper housing member  56  and a cylindrical lower housing member  58  which is secured to the upper housing member  56  as will be described hereinafter. Upper housing member  56  has an upper end  60  and a lower end  62 . A plurality of spaced-apart internally threaded openings  63  extend upwardly into the lower end of housing member  56 . An upper cylindrical bore  64  extends downwardly into housing member  56  from the upper end  60  thereof as seen in  FIG. 11 . A lower bore  66  extends upwardly into housing member  56  from the lower end  62  thereof. The lower end of bore  66  has a tapered portion  68 . As seen, the upper end of bore  66  has a diameter which is greater than the diameter of bore  64  thereby forming a shoulder  70  therebetween. Housing member  56  has external threads  71  formed on its lower end. 
     Actuator assembly  54  also includes an upper actuator element  72  having a cylindrical shaft  74  with an upper end  76  and a lower end  78 . Actuator element  72  has a downwardly presented semi-spherical ball  80  at its lower end. Prior to lower housing member  58  being secured to housing member  56 , spring  81  is inserted into bore  66  of housing member  56  so that the upper end  83  of spring  81  engages shoulder  70 . Actuator element  72  is then inserted into housing member  56  with shaft  74  extending upwardly into bore  64  with the lower end of spring  81  engaging ball  80 . 
     Actuator assembly  54  also includes a lower actuator element  82  having a cylindrical shaft  84  with an upper end  86  and a lower end  88 . Shaft  84  has a semi-spherical ball  90  formed therewith at the upper end  86  of shaft  84 . The upper end of ball  90  has a ball receiving socket  92  formed therein. The periphery of socket  92  is designated with the reference numeral  94 . 
     Lower housing member  58  has a tapered bore  96  extending upwardly thereinto from the lower end  98  of housing member  58 . Lower housing member  58  has a semi-spherical ball receiving socket  100  formed therein at the upper end thereof. Lower housing member  58  has a plurality of spaced-apart counter-sunk openings  102  extending upwardly thereinto from the lower end  98  of lower housing member  58  adapted to receive bolts  104  thereinto. 
     Prior to lower housing member  58  being secured to upper housing member  56 , shaft  84  of lower actuator element  82  is inserted downwardly through socket  100  and bore  96  so that semi-spherical ball  90  engages socket  100 . Lower housing member  58 , with lower actuator element  82  positioned therein, is secured to upper housing member  56  by the bolts  104 . When lower housing member  58  is secured to upper housing member  56 , spring  81  yieldably urges ball  80  of upper actuator element  72  into engagement with socket  92  of ball  90 . 
     A switch support bracket  106  is positioned within compartment  26  of lower housing  16 . Switch support bracket  106  includes a horizontally disposed base portion  108  which is secured to lower housing  16  by bolts  110  and  112 . Switch support bracket  106  also includes a wall portion  114  which extends upwardly from base portion  108 . Base portion  108  has a central slot or opening  116  formed therein. 
     A conventional, normally open electrical switch  118  is secured to wall portion  114  above base portion  108  by bolts  120  and  122 . Switch  118  includes a lever arm  124  which is pivotally secured, about a horizontal axis, to the switch body  126  by pivot pin  128 . A roller  130  is secured to the outer end of lever arm  124  by pivot pin  131  so that roller  130  extends downwardly into opening  116 . 
     To summarize somewhat, the sensor  10  is assembled and functions as will now be described. The actuator assembly  54  is assembly by inserting the spring  81  and upper actuator element into upper housing member  56  prior to lower housing member  58  being secured to upper housing member  56 . The lower actuator element  82  is then inserted into lower housing member  56 , as previously described. The bolts  104  are then inserted into the counter-sunk openings  102  and threaded into openings  63  in upper housing member  56  to secured lower housing member  58  to upper housing member  56 . When lower housing member  58  is secured to upper housing member  56 , spring  81  urges ball  80  into engagement with the socket  92  of ball  90 . 
     Bushing  50  is then inserted upwardly into opening  40 . Actuator assembly  54  is then threaded upwardly into tubular member  42  with threads  71  on upper housing member  56  engaging threads  48  on tubular member  42 . When actuator assembly  54  is secured to tubular member  42 , the upper end  76  of shaft  74  will be positioned, as seen in  FIG. 10 , so as to be closely positioned, if not engaging, the roller  130 . At that time, switch  118  is in an open position. The sensor  10  is then positioned in the containment structure  12 , as seen in  FIG. 1 , and secured thereto in a convenient manner usually with the threads  46 . 
     If not already connected, an elongated rod  132 , having a vane  133  on the lower end thereof, will be connected to the shaft  84  of lower actuator element  82  by a connector  136  which includes a spring  138  which yieldably maintains rod  132  in a vertically disposed attitude. Further, if not already installed, a flexible sleeve  140  will be positioned so as to extend between lower housing member  58  and the connector  136 . 
     When the sensor  10  is positioned in the containment structure  12 , as seen in  FIG. 1 , the sensor  10  does not come into play until the material  14  reaches the lower end of rod  132  at which time the vane  133  and the lower end of rod  132  will be moved laterally which causes lower actuator element  84  to laterally or angularly move. The angular movement of lower actuator element  84  causes the ball  90  to pivot with respect to ball  80  which causes upper actuator element  72  to move upwardly. The upward movement of shaft  74  causes the upper end  76  of shaft  74  to move the roller  130  upwardly which causes the lever arm  124  to pivotally move upwardly which causes the switch  118  to close. The switch  118  is electrically connected to an alarm or monitoring system (not shown) which will either deactivate the conveyor which is conveying material to the containment structure  12  or to alert personnel that the level of material in the containment structure has reached a certain level. 
     Thus it can be seen that the sensor of this invention accomplishes at least all of its stated objectives. 
     Although the invention has been described in language that is specific to certain structures and methodological steps, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific structures and/or steps described. Rather, the specific aspects and steps are described as forms of implementing the claimed invention. Since many embodiments of the invention can be practiced without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.