Patent Abstract:
A screening apparatus that includes a strainer element used for the purpose of retaining particulate while permitting the passage of a liquid through the strainer element, a support structure for the strainer element to enable rotation of the strainer element between opposed 180 degree positions, and a control member coupled with the strainer element for controlling the rotation of the strainer element. The strainer element, in both opposed positions thereof impedes any particulate while permitting the passage of a liquid. The control member is constructed so that, in a first state thereof, the rotation of the strainer element is periodically controlled to rotate the strainer element between said opposed 180 degree positions, and in a second state thereof, inhibits rotation of the strainer element.

Full Description:
FIELD OF THE INVENTION 
     The present invention relates in general to strainers that may be used in such applications as filtration and fluid flow safety. More particularly, the present invention relates to an improved strainer construction as well as an associated control system. Even more particularly, the present invention relates to a method of controlling a strainer element. 
     BACKGROUND OF THE INVENTION 
     In the field of filtration and fluid flow safety there is relatively common use of a device that is identified as a strainer. The strainer or screening device is used to retain foreign objects. The strainer is usually a fixed position device. It is typical to provide access to the strainer for cleaning the strainer. However, this access is many times not very convenient. Also, the typical strainer device is not suited for the receipt and processing of objects that are the result of an upstream breakage or destruction. 
     Accordingly, it is an object of the present invention to provide an improved screening apparatus in the form of a strainer element, and in which the strainer element is rotatable through 180 degrees in accordance with one mode of operation. This mode of operation enables any foreign objects collected at the strainer to be periodically released. 
     Another object of the present invention is to provide a control system for controlling a strainer, particularly as to its rotation parameter. The system of the present invention provides an improvement in the overall process so as to maximize the uptime of the process, while simultaneously protecting against any upset or unacceptable event that may occur downstream of the strainer. 
     Still another object of the present invention is to provide a control system for controlling a strainer element that enables the strainer element, in one mode of operation, to be locked in position so that any foreign objects, debris or detritus is retained at the strainer element for subsequent collection. In accordance with another mode of operation of the control system of the present invention, foreign objects, particularly debris or detritus, may be diverted to a collection receptacle. 
     A further object of the present invention is to provide a method of controlling a strainer element that is used for the purpose of retaining particulate while permitting the passage of a liquid through the strainer element, and in which control is of, not only the rotation of the strainer element, but also control of valves so as to divert debris or detritus to a collection receptacle. 
     SUMMARY OF THE INVENTION 
     To accomplish the foregoing and other objects, features and advantages of the present invention there is provided a screening apparatus comprising a strainer element used for the purpose of retaining particulate while permitting the passage of a liquid through the strainer element, a support structure for the strainer element to enable rotation of the strainer element between opposed 180 degree positions, and a control member coupled with the strainer element for controlling the rotation of the strainer element. The strainer element, in both opposed positions thereof impedes any particulate while permitting the passage of a liquid. The control member is constructed and arranged so that, in a first state thereof, the rotation of the strainer element is periodically controlled to rotate the strainer element between said opposed 180 degree positions, and in a second state thereof, inhibits rotation of the strainer element. 
     In accordance with other aspects of the present invention the support structure includes a frame, and the strainer element includes a circular strainer member mounted in the frame and a shaft for supporting the strainer member relative to the frame; the control member includes an electro-mechanical mechanism that, in the first state periodically controls the rotation of the shaft between the opposed positions, and in the second state inhibits rotation of the shaft; including a downstream processing device that has the ability to generate a fault signal, the fault signal for controlling the electro-mechanical mechanism, in its second state, to inhibit rotation of the circular strainer member; including, in combination therewith, a first valve disposed upstream of the strainer element and having open and closed positions, the first valve being in the open position in the first state, and being in the closed position in the second state; including, in combination therewith, a second valve disposed upstream of the strainer element and having closed and open positions, the second valve being in the closed position in the first state, and being in the open position in the second state; the control member includes a timer set to determine the periodic control; the control member includes a pressure sensor to determine the periodic control. 
     In accordance with another aspect of the present invention there is provided a control system for controlling a strainer element that is used for the purpose of retaining particulate while permitting the passage of a liquid through the strainer element, the strainer element rotatable between opposed 180 degree positions, and an electrical controller coupled with the strainer element and for controlling the rotation of the strainer element. The strainer element, in both opposed positions thereof impedes any particulate matter while permitting the passage of a liquid through the strainer element. The electrical controller is constructed and arranged so that, in a first state thereof, the rotation of the strainer element is periodically controlled to rotate the strainer element between the opposed 180 degree positions, and in a second state thereof, is controlled to inhibit rotation of the strainer element. 
     In accordance with still other aspects of the present invention the rotation of the strainer element includes a support structure having a frame, and the strainer element includes a circular strainer member mounted in the frame and a shaft for supporting the strainer member relative to the frame, the shaft being rotatable in order to rotate the circular strainer member; further including an electro-mechanical mechanism that, in the first state periodically controls the rotation of the shaft and, in turn, the circular strainer member between the opposed positions, and in the second state inhibits rotation of the shaft and, in turn, the circular strainer member; including a downstream processing device that generates a fault signal in response to a fault condition that has occurred, said fault signal for controlling the electro-mechanical mechanism, its second state, to inhibit rotation of said circular strainer member; including a first valve disposed upstream of said strainer element and having open and closed positions, said first valve being in the open position in the first state, and being in the closed position in the second state; including a second valve disposed upstream of said strainer element and having closed and open positions, said second valve being in the closed position in the first state, and being in the open position in the second state; the electrical controller includes a timer set to determine the periodic control; including a downstream processing device that generates a fault signal in response to a fault condition that has occurred and wherein said electrical controller further includes a gate device that is coupled from the timer and also receives the fault signal; the control member includes a pressure sensor to determine the periodic control; including a downstream processing device that generates a fault signal in response to a fault condition that has occurred and wherein said electrical controller further includes a gate device that is coupled from the pressure sensor and also receives the fault signal. 
     In accordance with still other aspects of the present invention there is provided a method of controlling a strainer element that is used for the purpose of retaining particulate while permitting the passage of a liquid through the strainer element, comprising controlling the strainer element so as to rotate between opposed 180 degree positions, controlling the strainer element so that the strainer element, in both opposed positions thereof, impedes any particulate matter while permitting the passage of a liquid through the strainer element, controlling, in a first state, the rotation of the strainer element so that the strainer element is periodically rotated between said opposed 180 degree positions, and controlling in a second state thereof, so as to inhibit rotation of the strainer element. Other aspects include providing a first valve disposed upstream of said strainer element and having open and closed positions, controlling said first valve to be in the open position in the first state, and controlling said first valve to be in the closed position in the second state; providing a second valve disposed upstream of said strainer element and having closed and open positions, controlling said second valve to be in the closed position in the first state, and controlling said second valve to in the open position in the second state; and providing a downstream processing device that generates a fault signal in response to a fault condition that has occurred, said fault signal for controlling said first and second valves. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       It should be understood that the drawings are provided for the purpose of illustration only and are not intended to define the limits of the disclosure. In the drawings depicting the present invention, all dimensions are to scale. The foregoing and other objects and advantages of the embodiments described herein will become apparent with reference to the following detailed description when taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a diagram of a first embodiment of a strainer control system in accordance with the present invention and employing a timer control; 
         FIG. 2  is diagram of a second embodiment of a strainer control system in accordance with the present invention and employing a pressure sensor; 
         FIG. 3  is a diagram showing somewhat further detail relating to the fault event; 
         FIG. 4  is a diagram showing further details at the strainer element to illustrate the rotation of the strainer element; 
         FIG. 5  is a perspective view of the strainer element for illustrating the 180 degree rotation of the strainer element; 
         FIG. 6  is a partial system diagram of an alternate embodiment of that described in  FIG. 1 ; 
         FIG. 7  is a timing diagram associated with the system illustrated in  FIG. 1 ; 
         FIG. 8  is a timing diagram associated with the system of  FIG. 6 ; and 
         FIG. 9  is an alternate diagram of a strainer control system in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference is now made to the block diagrams illustrating different modes of operation of the strainer and associated control system for the strainer. One of the purposes of the control system, along with the unique construction of the strainer element, is to maximize the up-time of the system operation. Another feature that is described with regard to the block diagrams is a system for protecting against any fault event or process upset when debris or detritus become entrained in the fluid flow. 
       FIG. 1  is a schematic block diagram of a first embodiment of the present invention in which the strainer element is controlled for rotation by means of a timer. The second embodiment of the present invention is shown in the block diagram of  FIG. 2  in which pressure sensing occurs at the strainer and the rotation of the strainer in turn is controlled by a pressure sensor that senses a pressure differential at the strainer.  FIGS. 3-5  show further details associated with either the system of  FIG. 1  or the system of  FIG. 2 .  FIG. 6  shows an alternate simplified control diagram. Finally,  FIGS. 7 and 8  are timing diagrams associated with the different embodiments described herein. 
     With reference to the schematic block diagram of  FIG. 1 , there is illustrated a flow line  10  shown coupled to a fault detector  12  by way of the line or piping  11 . Upstream of the fault detector  12  is the strainer  14  of the present invention. The system illustrated in  FIG. 1  also includes a downstream valve  16  coupled by way of the piping  17  from the strainer  14 . A divert pipe  19  is also shown coupling from the piping  17  to a second valve  18 . The second valve  18  can, in turn, connect by way of piping to the collection receptacle  20 . The diversion via the valve  18  allows a diversion path of detritus, such as from a fault event. This fault event may be, for example, when a Uv tube, used in a filtration system, breaks and parts of the tube assembly flow to the strainer and are held at the strainer. 
     In the system in  FIG. 1 , under normal operating conditions, when there is no fault detected, the controller  24  provides the following operation. Controller  24  may be an electrical controller and is illustrated as including a timer  26  and a gate  28 . Under normal, no fault, operation, a timing signal from the timer  26  is coupled by way of the gate  28  to the strainer  14 . This action enables the strainer  14  to rotate through 180 degrees thus releasing any foreign objects that had been retained by the strainer. This basic operation is illustrated in  FIG. 6  wherein the output of the gate  28  couples only to the strainer element  14 . Under a no-fault condition the signal from gate  28  to the valves  16  and  18  is such that both of these valves are maintained in a normal position. The valve  16  is normally open and the valve  18  is normally closed. Thus, under that no fault condition, when the strainer  14  is rotated any foreign objects are coupled by way of the piping  17  and the valve  16  to a discharge point or location at  21 . Actually, in the version in  FIG. 6  that operation is possible without controlling either of the valves  16  or  18 . 
     If a fault event occurs, and with further reference to  FIG. 3 , then an error signal is generated on line  30 .  FIG. 3  illustrates one of many different fault conditions that may occur.  FIG. 3  illustrates, for example, a UV tube assembly at  32  that has a fault detector  34  associated therewith. If one of the UV tubes breaks then a signal is generated from detector  34  on the error signal line  30  coupled to the electrical controller  24  and in turn to the sensing gate  28 . Under that condition, the output from the gate  28  controls the strainer  14 , and the valve  16  as well as the valve  18 . The signal from the gate  28  causes the strainer  14  to rotate releasing any of the detritus such as pieces from the UV tube. However, it is desired in accordance with that fault mode of operation that any of the foreign objects, instead of being discharged through the valve  16  to location  21 , are discharged through the valve  18  to the collection receptacle  20 . Thus, in that mode of operation when the output is generated at the gate  28 , this causes the valve  16  to switch from a normally open to a closed position. This blocks the flow of liquid to the discharge at  21 . At the same time, the valve  18 , which is a normally closed valve, opens and thus the foreign objects are conveyed from the strainer  14 , by way of the valve  18 , to the collection receptacle  20 . This collection receptacle is particularly suited for receiving fault derived items for inspection thereof. 
     With reference to the schematic block diagram of  FIG. 2 , many of the same reference numbers are used as illustrated in  FIG. 1  to identify basically the same components. In  FIG. 2  there is illustrated a flow line  10  shown coupled to a fault detector  12  by way of the line or piping  11 . Upstream of the fault detector  12  is the strainer  14  of the present invention. The system illustrated in  FIG. 2  also includes a downstream valve  16  coupled by way of the piping  17  from the strainer  14 . A divert pipe  19  is also shown coupling from the piping  17  to a second valve  18 . The second valve  18  can, in turn, connect by way of piping to the collection receptacle  20 . The diversion via the valve  18  allows a diversion path of detritus, such as from a fault event. This fault event may be, for example, when a Uv tube, used in a filtration system, breaks and parts of the tube assembly flow to the strainer and are held at the strainer. 
     In the system in  FIG. 2 , under normal operating conditions, when there is no fault detected, the controller  24  provides the following operation. Controller  24  may be an electrical controller and is illustrated as including a pressure sensor  27  and a gate  28 . Under normal, no fault, operation, a timing signal from the pressure sensor  27  is coupled by way of the gate  28  to the strainer  14 . This action enables the strainer  14  to rotate through 180 degrees thus releasing any foreign objects that had been retained by the strainer. This basic operation is illustrated in  FIG. 6  wherein the output of the gate  28  couples only to the strainer element  14 . Under a no-fault condition the signal from gate  28  to the valves  16  and  18  is such that both of these valves are maintained in a normal position. The valve  16  is normally open and the valve  18  is normally closed. Thus, under that no fault condition, when the strainer  14  is rotated any foreign objects are coupled by way of the piping  17  and the valve  16  to a discharge point or location at  21 . Actually, in the version in  FIG. 6  that operation is possible without controlling either of the valves  16  or  18 . 
     In  FIG. 2 , rather than using a timer the control at the gate  28  is from the pressure sensor  27 . The pressure sensor  27  is responsive to a sensed differential pressure at the strainer  14 . For that purpose a pair of pressure sensors may be disposed at opposite upstream and downstream sides of the strainer in order to detect a differential pressure essentially across the strainer  14 . This differential pressure is illustrated in  FIG. 2  by the feedback line  29  that couples from the pair of sensors at the strainer  14  to the pressure sensor  27 . The pressure sensor  27  may have a threshold level that is set so that once a predetermined differential pressure is reached, as detected on line  29 , the pressure sensor  27  sends a signal to the gate  28  as previously described in connection with the operation of the embodiment shown in  FIG. 1 . 
       FIGS. 4 and 5  describe further details of the strainer element. The strainer element  14  may be considered as comprised of a main support frame  40 , the rotatable strainer  42  and support shaft  44 . The strainer  42  is fixedly attached to the shaft  44  and rotates upon rotation of the shaft  44 . The shaft  44  is supported within the frame  40 . Bearings (not shown) may be provided at opposite ends of the shaft  44  between the shaft  44  and the frame  40 . These additional details are schematically described in  FIG. 4 .  FIG. 4  also illustrates the controller  24  and an electro-mechanical mechanism  46  that is disposed between the controller  34  and the shaft  44 . The electro-mechanical mechanism converts an electrical signal from the controller  24  into a mechanical motion; or in other words causes a 180 degree rotation of the shaft  44 . As indicated previously, this rotation may be based either upon a timer, a pressure sensor or may even be based on other input parameters, including but not limited to temperature or temperature differential. Rotation of the shaft  44  causes immediate rotation of the strainer  42 . 
     With reference to the schematic block diagram of  FIG. 6 , many of the same reference numbers are used as illustrated in  FIGS. 1 and 2  to identify basically the same components. In  FIG. 6  there is illustrated a flow line  10  shown coupled to a fault detector  12  by way of the line or piping  11 . Upstream of the fault detector  12  is the strainer  14  of the present invention. In the system in  FIG. 6 , under normal operating conditions, when there is no fault detected, the controller  24  provides the following operation. Controller  24  may be an electrical controller and is illustrated as including a timer  26  and a gate  28  (or alternatively a pressure sensor as in  FIG. 2 ). Under normal, no fault, operation, a timing signal from the timer  26  is coupled by way of the gate  28  to the strainer  14 . This action enables the strainer  14  to rotate through 180 degrees thus releasing any foreign objects that had been retained by the strainer. This basic operation is illustrated in  FIG. 6  wherein the output of the gate  28  couples only to the strainer element  14 . 
     With reference to the schematic block diagram of  FIG. 9  there is illustrated a flow line  10  shown coupled to a fault detector  12  by way of the line or piping  11 . The fault detector may be the same as illustrated in  FIG. 3  including a detector  34  that essentially issues a “fault” signal upon a fault occurring such as a breakage of a component. Downstream of the fault detector  12  is the strainer  14  of the present invention. The system illustrated in  FIG. 9  also includes a downstream valve  16  coupled by way of the piping  17  from the strainer  14 . A divert pipe  19  is also shown coupling from the piping  17  to a second valve  18 . The second valve  18  can, in turn, connect by way of piping to the collection receptacle  20 . The diversion via the valve  18  allows a diversion path of detritus, such as from a fault event. This fault event may be, for example, when a Uv tube, used in a filtration system, breaks and parts of the tube assembly flow to the strainer and are held at the strainer for release to a specific collection receptacle. 
     In the system in  FIG. 9 , under normal operating conditions, when there is no fault detected, the controller  24  provides the following operation. Controller  24  may be an electrical controller and is illustrated as including a timer  26  and a series of electronic control gates identified in  FIG. 9  as an inverter  50 , an AND gate  52 , and an OR gate  54 . Under normal, “no fault”, operation, a timing signal from the timer  26  is coupled by way of the gate  52  and gate  54  to the strainer  14 . This action enables the strainer  14  to rotate through 180 degrees thus releasing any foreign objects that had been retained by the strainer. This basic operation is also illustrated in  FIG. 6  wherein the output of the gate  28  couples only to the strainer element  14 . Under a “no-fault” condition the valves  16  and  18  are operated such that both of these valves are maintained in a normal position. The valve  16  is normally open and the valve  18  is normally closed. Thus, under that “no fault” condition, when the strainer  14  is rotated any foreign objects are coupled by way of the piping  17  and the valve  16  to a discharge point or location at  21 . 
     In a “no fault” state, one can consider that the signal on line  30  is at a logical “0” level. This signal is inverted at the inverter gate  50  so that the signal on the line is at a logical “1” state. This signal, along with the output of the timer  26  on line  55  is coupled to the AND gate  52 . The signal on line  51  essentially enables the gate  52  so that any signal pulse from the timer  28  is coupled directly through the AND gate  52  to the OR gate  54 , and, in turn, via the delay circuit  56  and lines  57  and  58  to the strainer  14  for control of the rotation of the strainer  14 . The periodic output from the timer  26  may be a pulse for operating the electro-mechanical mechanism  46  (see  FIG. 4 ) to cause periodic rotation of the strainer  14 . Alternatively, a pressure sensing arrangement may be used in place of the timer, as in  FIG. 2 . The output of the timer is controlled through the OR gate  54  and the delay  56  to operate the rotation of the strainer  14 . Under that same “no fault” condition the logical “0” on line  53  directly controls the valves  16  and  18  so that both of the valves are maintained in their normal, unactuated state. In that state the valve  16  is normally open and the valve  18  is normally closed. Thus, under this “no fault” condition, when the strainer  14  is rotated any foreign objects are coupled by way of the piping  17  and the valve  16  to a discharge point or location at  21 . 
     If a “fault” event occurs, and with further reference to  FIG. 3 , then an error signal is generated on line  30 .  FIG. 3  illustrates one of many different fault conditions that may occur.  FIG. 3  illustrates, for example, a UV tube assembly at  32  that has a fault detector  34  associated therewith. If one of the UV tubes breaks then a signal is generated from detector  34  on the error signal line  30  coupled to the electrical controller  24  and in turn to the sensing gates  50  and  54 . Under that condition, the output from the inverter gate  50  goes to a logical “0” essentially inhibiting the AND gate  52  so that the rotation of the strainer  14  is no longer controlled from the timer. However, the logical “1” signal on input line  30  is coupled via line  53  into one of the two inputs of the OR gate  54 . This logical “1” signal on line  53  is coupled via the OR gate  54  and the delay circuit  56  to control rotation of the strainer  14 . The delay circuit may be optional. It can be used to delay the rotation signal to the strainer  14  so that one is assured that the valves  16  and  18  are switched to their alternate position before the valves change state. In that way any fault derived items are recovered in the receptacle  20 , and not discharged to location  21 . 
     It is desired in accordance with this “fault” mode of operation that any of the foreign objects (event items), instead of being discharged through the valve  16  to location  21 , are discharged through the valve  18  to the collection receptacle  20 . Thus, in this mode of operation when the output is generated at the line  53 , this causes the valve  16  to switch from a normally open to a closed position. This blocks the flow of liquid to the discharge at location  21 . At the same time, the valve  18 , which is a normally closed valve, opens and thus the foreign objects (event items) are conveyed from the strainer  14 , by way of the valve  18 , to the collection receptacle  20 . This collection receptacle  20  is particularly suited for receiving fault derived items for inspection thereof. 
     Having now described a limited number of embodiments of the present invention, it should now be apparent to those skilled in the art that numerous other embodiments and modifications thereof are contemplated as falling within the scope of the present invention, as defined by the appended claims. For example, the strainer that has been used is considered as rotating through 180 degrees between positions. However, there may be other strainer configurations in which opposite positions could be attained by means of rotation amounts less than or greater than 180 degrees.

Technology Classification (CPC): 2