Patent Publication Number: US-11640864-B2

Title: System and method for detecting position of a solenoid plunger

Description:
FIELD 
     The present disclosure relates to electromagnetic control devices, and specifically to solenoid assemblies and a system and method for determining and indicating plunger position. 
     BACKGROUND 
     Conventional solenoid assemblies include a coil or winding that defines a hollow passageway. A plunger positioned in the passageway moves between different positions as electrical power is applied to the coil. For instance, when electrical power is applied the coil, the plunger moves from a retracted position to an extended position. A return spring can be included in the solenoid assembly to move the plunger back to the retracted position when electrical power is no longer applied to the coil. An example of a conventional solenoid assembly is described in U.S. Pat. No. 7,864,008, which is incorporated herein by reference in entirety. 
     The plunger often has a plunger end that extends from a frame when the plunger is in the extended position, and the plunger end often performs some type of function or engages with an object. In one exemplary example, the plunger end extends from the solenoid frame and is received into a hole of an object to thereby lock movement of the object relative to the solenoid frame. In this example, the object cannot move relative to the frame until the plunger moves to the retracted position and the plunger end retracts into the frame. It can be appreciated that when the plunger end does not align with a locking recess of the object, the plunger end may contact the object such that the plunger does not fully move into extended position. In this blocked position, the plunger will not lock the object into the desired state. Thus, there is a need for a system and method for determining and indicating if the plunger actually moves into the fully extended position when the coil is energized. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. 
     In certain examples, a solenoid assembly includes a solenoid having a coil that defines a passageway and a plunger movable within the passageway from a retracted position to an extended position. In one embodiment, such movement occurs when the coil is energized. The plunger extends along an axis between a first plunger end and an opposite second plunger end. The second plunger end is designed to engage an object to carry out the designed functionality of the solenoid in a specific use application. A frame holds the solenoid and has a first opening through which the first plunger end extends when the plunger is in the retracted position and a second opening through second end of the plunger extends when the plunger is in the extended position. When the plunger is in the extended position the first plunger end retracts into the frame via the first opening. 
     In certain examples, a method for determining position of a plunger movable in a solenoid having a coil that defines a passageway includes the steps of positioning a plunger in the passageway such that the plunger moves in the passageway from a retracted position to an extended position. The plunger extends along an axis between a first plunger end and a second plunger end. The method further includes positioning the solenoid in a frame that has a first opening through which the first plunger end extends when the plunger is in the retracted position and a second opening through second plunger end extends when the plunger is in the extended position and sensing. A sensor is positioned on the solenoid frame to detect the state of the first plunger end. When the sensor detects the first plunger end extending through the first opening, the sensor generates a first electrical output. If the sensor does not detect the first plunger end, the sensor generates a second electrical output, where the first and second electrical outputs could be different electrical values or a simple on/off state. The method can further include determining with a control system position of plunger based on the electrical output generated by the sensor. 
     Various other features, objects, and advantages will be made apparent from the following description taken together with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is described with reference to the following Figures. The same numbers are used throughout the Figures to reference like features and like components. 
         FIG.  1    is a perspective view of an example solenoid assembly of the present disclosure. 
         FIG.  2    is a cross-sectional view of the solenoid assembly of  FIG.  1    with a plunger in a retracted position and a second plunger end aligned with a hole in an object. 
         FIG.  3    is a cross-sectional view of the plunger. 
         FIG.  4    is a cross-sectional view of the solenoid assembly of  FIG.  1    with the plunger in an extended position and the second plunger end extending into the hole of the object. 
         FIG.  5    is a cross-sectional view of the solenoid assembly of  FIG.  1    with the plunger in an intermediate position and the second plunger end contacting the object. 
         FIG.  6    is schematic diagram of an example control system of the present disclosure. 
         FIG.  7    is an example method for determining and indicating position of the plunger in the solenoid assembly of the present disclosure. 
     
    
    
     DETAILED DISCLOSURE 
       FIGS.  1  and  2    illustrate a solenoid assembly  10  of the present disclosure. The assembly  10  generally extends along an axis  13  between a first end  11  and an opposite second end  12 . The assembly  10  includes a solenoid  20  held in a frame  16  and a plunger  50  that moves relative to the frame  16  and the solenoid  20 . 
     The solenoid  20  has an electromagnetic coil  21  that defines a cylindrical interior passageway  24  in which the plunger  50  moves. The coil  21  is surrounded by a protective housing  22 , and electrical wires or contact arms  25  extend through the protective housing  22  to connect the coil  21  to an electrical power source (not shown). A plug  27  is received in the passageway  24 , and the plug  27  extends out of the passageway  24  in a direction toward the second end  12  of the assembly  10 . The plug  27  is generally cylindrical with a bore  30  extending there through. The plug  27  has a frusto-conical cutout  28  and a funnel-shaped backstop surface  29  (described further herein). In certain examples, the plug  27  can be made from a magnetic steel component that completes a magnetic circuit when the gap between the plunger  50  and the plug  27  is closed upon energization of the coil  21 . 
     As noted above, the solenoid  20  is held by the frame  16 , and in the example depicted, the frame  16  includes multiple sections that are coupled together. The frame  16  includes mounting arms  17  positioned at the second end  12  of the assembly  10 . The mounting arms  17  are for mounting the assembly  10  to another object. The frame  16  also includes a sensor mount  18  at the first end  11  of the assembly  10  to which a plunger sensor (described below) is coupled. The sensor mount  18  is generally “U”-shaped with two parallel arms  19 . 
     The frame  16  defines a pair of cavities  40 A,  40 B that extends along the axis  13 , and the cavities  40 A,  40 B align with the passageway  24 . Specifically, a first cavity  40 A extends along the axis  13  from the passageway  24  toward the first end  11  of the assembly  10  and a second cavity  40 B extends along the axis  13  from passageway  24  toward the second end  12  of the assembly  10 . The frame  16  also has a first opening  41  at the first end  11  of the assembly  10 , and the first opening  41  is in communication with the first cavity  40 A. A second opening  42  in the frame  16  is at the second end  12  of the assembly  10 , and the second opening  42  is in communication with the second cavity  40 B. The openings  41 ,  42  align with the axis  13 . 
     The plunger  50  extends in the passageway  24  and the cavities  40 A,  40 B and moves axially as the solenoid  20  energizes and de-energizes as electrical power is applied or not applied, respectively, to the coil  21 . The plunger  50  extends along the axis  13  and has a first plunger end  51  at the first end  11  of the assembly  10  and an opposite second plunger end  52  at the second end  12  of the assembly  10 . Note that operation of the assembly  10  and movement of the plunger  50  is described herein below. 
     Referring to  FIG.  3   , the plunger  50  is depicted in greater detail. The plunger  50  has an indicator tab  64  at the first plunger end  51 , a locking pin  60  at the second plunger end  52 , and a body  53  and a stem  58  that extend between the body  53  and the locking pin  60 . The body  53  has a cylindrical first section  54  and a tapered furstro-conical second section  55 . The first section of the body  53  has a first diameter D 1  which corresponds to the diameter of the passageway  24  ( FIG.  2   ). The second section  55  has an outer perimeter seating surface  56  that corresponds to the backstop surface  29 . In the certain examples, the outer perimeter seating surface  56  is in the shape of a funnel. The stem  58  extends from the second section  55  of the body  53  and has a second diameter D 2  which corresponds to the diameter of the bore  30  ( FIG.  2   ) such that the stem  58  extends through the bore  30 . 
     The indicator tab  64  is connected to the body  53 , and the indicator tab  64  has a fourth diameter D 4  that is less than the first diameter D 1  of the body  53 . The fourth diameter D 4  can be equal to or less than the diameter of the first opening  41  ( FIG.  2   ) such that the indicator tab  64  is movable through the first opening  41  (described further herein below). The locking pin  60  is connected to the stem  58  and has a first groove  61  and a second groove  62  that each encircle the stem  58 . The locking pin  60  has a third diameter D 3  that is greater than the second diameter D 2  of the stem  58  and less than the first diameter D 1  of the body  53 . The third diameter D 3  can be equal to or less than the diameter of the second opening  42  such that the locking pin  60  is movable through the second opening  42  (described further herein below). Note that the diameters D 1 , D 2 , D 3 , D 4  of the different components of the plunger  50  can vary, and further, the diameters D 1 , D 2 , D 3 , D 4  may vary relative to each other for the example plunger  50  depicted in  FIG.  3   . For instance, in one non-limiting example the second diameter D 2  of the stem  58  equals the third diameter D 3  of the locking pin  60 . 
     Referring now to  FIGS.  2  and  4   , an example operational sequence of the assembly  10  is depicted.  FIG.  2    depicts the coil  21  de-energized (electrical power is not flowing through the coil  21 ). Accordingly, the plunger  50  is in a retracted position in which the first plunger end  51  extends through the first opening  41  in the frame  16  and the second plunger end  52  is retracted into the frame  16 . Specifically, the indicator tab  64  at the first plunger end  51  extends through the first opening  41  and into an area between the arms  19  of the sensor mount  18  as shown in  FIG.  1   . In this position, the indicator tab  64  is exposed and visible from outside the frame  16 . At the same time, the second end  52  of the plunger  50  is retracted into the second cavity  40 B via the second opening  42  in the frame  16 . Specifically, the locking pin  60  at the second plunger end  52  is inside the second cavity  40 B and does not extend from the frame  16 . 
     In the embodiment shown, the plunger  50  is biased into the retracted position by a return spring  70  that has a first spring end  71  coupled to the plunger  50  and an opposite second end  72  coupled to the frame  16 . The return spring  70  is positioned in the second cavity  40 B, and the first spring end  71  is received in the second groove  62  of the plunger  50 . The return spring  70  opposes movement of the plunger  50  in a first direction (see arrow A) toward the second end  12  of the assembly  10 . 
     A diaphragm  80  is postioned between the plunger  50  and the frame  16 . Specifically, the diaphragm  80  has an interior first perimeter edge  81  coupled to the plunger  50  and an opposite exterior perimeter edge  82  coupled to the frame  16 . The diaphragm  80  is located in the second cavity  40 B. The first perimeter edge  81  is received in the first groove  61  of the plunger  51  and the second perimeter edge  82  is clamped between two sections of the frame  16 . The diaphragm  80  is positioned to prevent debris and/or moisture near the second end  12  of the assembly  10  from moving in a second direction (see arrow B) toward the first end  11  of the assembly  10 . For instance, the diaphragm  80  prevents debris and/or moisture from moving from the second cavity  40 B and into the passageway  24 . The diaphragm  80  in this example is disc-shaped with a center aperture  83  defined by the first perimeter edge  81 . Note that in other examples, the position, size, and/or shape of the diaphragm  80  can vary to any suitable position, size, and/or shape. 
       FIG.  4    depicts the coil  21  as energized (electrical power is flowing through the coil  21 ) with the plunger in an extended position. When the coil  21  is energized, the plunger  50  moves in the first direction (see arrow A) toward the second end  12  of the assembly  10  and into an extended position, as depicted in  FIG.  4   . In the extended position, the indicator tab  64  at the first plunger end  51  is retracted through the first opening  41  and thereby the indicator tab  64  is in the first cavity  40 A and does not extend out of the frame  16  via the first opening  41 . In addition, the second plunger end  52  extends through the second opening  42  and out of the frame  16 . When the plunger is in the extended position, the locking pin  60  at the second plunger end  52  extends out from the second cavity  40 B and the frame  16 . Thus, the locking pin  60  can engage with another object, such as a plate  90 . In this example, the locking pin  60  extends into a hole  91  defined in the plate  90  when the hole  91  is aligned with the second opening  42  in the frame  16 . 
     As the plunger  50  moves from the retracted position ( FIG.  2   ) into the extended position ( FIG.  4   ), the plunger  50  compresses the return spring  70 . In addition, the diaphragm  80  flexes downward and the first perimeter edge  81  moves with the plunger  50  such that the shape of the diaphragm  80  changes. However, the second perimeter edge  82  of the diaphragm  80  remains coupled to the frame  16  such that the diaphragm  80  does permit debris and/or moisture to move into the passageway  24 , as noted above. Furthermore, the second section  55  of the body  53  moves into the cutout  28  of the plug  27  and the funnel surface  56  contacts the backstop surface  29 . Thus, contact between the funnel surface  56  and the backstop surface  29  limits the movement of the plunger  50  toward the second end  12  of the assembly  10 . 
     When electrical power no longer flows through the coil  21 , the return spring  70  moves the plunger  50  back into the de-energized, retracted position ( FIG.  2   ). Following this movement, the indicator tab  64  of the first plunger end  51  again extends through the first opening  41  in the frame  16  and the locking pin  60  at the second plunger end  52  is retracted into the frame  16 , as described above. Furthermore, the diaphragm  80  also flexes and moves with the plunger  50 . 
       FIG.  5    illustrates a condition in which the coil  20  is energized but the plate  90  is misaligned with the solenoid, which prevents the plunger  51  from moving into the extended position. In the misaligned position, the locking pin  60  on the second end  52  of the plunger cannot be received in the hole  91  in the plate  90 . Thus the plunger  50  cannot completely move into the energized position ( FIG.  4   ) because the locking pin  60  at the second plunger end  52  of the plunger  50  makes contact with the plate  90 . Thus, the locking pin  60  is not received in the hole  91  in the plate  90  and the plunger  50  does not move into the energized position ( FIG.  4   ). When the movement of the plunger  51  is blocked, the indicator tab  64  at the first plunger end  51  cannot fully retract into the first cavity  40 A of the frame  16  via the first opening  41  and the indicator tab  64  remains exposed and extends into the area between the arms  19  of the sensor mounting  18 . When these conditions occur, the solenoid assembly  10  is not properly operating or functioning and the exposed indicator tab  64  provides a visual indicator that the plunger  51  is not properly operating and not in the extended position. Thus, a technician can be alerted to the improper operation of the assembly  10  by visual inspection. 
     The assembly  10  includes a control system  100  that determines the position of the plunger  50  and the activation state of the solenoid and thereby determine if the solenoid assembly is operating properly. Generally, a control system  100  determines the position of the plunger  50  by monitoring the position of the indicator tab  64  and/or determines whether or not the solenoid assembly  10  is operating properly or improperly. 
     Note that certain aspects of the present disclosure are described or depicted as functional and/or logical block components or processing steps, which may be performed by any number of hardware, software, and/or firmware components configured to perform the specified functions. For example, certain embodiments employ integrated circuit components, such as memory elements, digital signal processing elements, logic elements, look-up tables, or the like, configured to carry out a variety of functions under the control of one or more processors or other control devices. The connections between functional and logical block components are merely exemplary, which may be direct or indirect, and may follow alternate pathways. 
     Referring to  FIG.  6   , the control system  100  may be a computing system that includes a processing system  110 , memory system  120 , and input/output (I/O) system  130  for communicating with other devices, such as input devices and output devices (described herein), either of which may also or alternatively be stored in a cloud  102 . The processing system  110  loads and executes an executable program  122  from the memory system  120 , accesses data  121  stored within the memory system  120 , and directs the control system to operate as described in further detail below. 
     The processing system  110  may be implemented as a single microprocessor or other circuitry, or be distributed across multiple processing devices or sub-systems that cooperate to execute the executable program  122  from the memory system  120 . Non-limiting examples of the processing system include general purpose central processing units, application specific processors, and logic devices. 
     The memory system  120  may comprise any storage media readable by the processing system  110  and capable of storing the executable program  122  and/or data  121 . The memory system  120  may be implemented as a single storage device, or be distributed across multiple storage devices or sub-systems that cooperate to store computer readable instructions, data structures, program modules, or other data. The memory system  120  may include volatile and/or non-volatile systems, and may include removable and/or non-removable media implemented in any method or technology for storage of information. The storage media may include non-transitory and/or transitory storage media, including random access memory, read only memory, magnetic discs, optical discs, flash memory, virtual memory, and non-virtual memory, magnetic storage devices, or any other medium which can be used to store information and be accessed by an instruction execution system, for example. 
     As noted above, the control system  100  communicates with and is operably connected to input devices and output devices. Example input devices include a plunger sensor  150 , a coil activation sensor  152 , and/or user input devices  154 . The plunger sensor  150  is configured to sense the position of the plunger  50 , such as by monitoring for the presence of the indicator tab  64 . The plunger sensor  150  can be any suitable device such as a photoelectric sensor, a reflective-type photoelectric sensor, and the like. The coil sensor  152  is configured to sense if the coil  21  is energized or de-energized. In embodiments in which the processing system  110  controls the activation of the solenoid, the coil sensor  152  could be eliminated since processing system  110  would control the activation of the solenoid. The user input device  154  is configured to receives inputs, such as instructions, selections, and/or data from a user. The user input device  154  can be any suitable device such as a touch screen, a personal computer, personal cellular phones, and the like. Examples of output devices include indicators  160  such as audio devices (e.g., speakers), visual alarms (e.g., lights), and the like. 
     In one example, a plunger sensor  150  is a photoelectric sensor that detects the presence of the indicator tab  64  adjacent to the sensor and generates an electrical output based on the presence or lack of presence of the indicator tab  64 . The electrical output could be an on/off state or varying voltage level depending upon whether the indicator tab  64  is detected. 
     In one example, the plunger sensor  150  is coupled to the sensor mount  18  at the first end  11  of the assembly  10  and oriented toward the indicator tab  64 . When the plunger  50  is in the retracted position ( FIG.  2   ), such that the indicator tab  64  at the first end  51  of the plunger  50  extends through first opening  41  in the frame  16 , the plunger sensor  150  senses the indicator tab  64  and thereby generates a first electrical output  151 , which is shown as the “off” state. When the plunger  50  is in the energized, extended position ( FIG.  4   ), such that the indicator tab  64  is retracted into the frame  16 , the plunger sensor  150  does not sense the tab  64  and a second electrical output  153  is generated, which is shown as the “on” state. In the state shown in  FIG.  5    in which the solenoid coil is energized but the locking pin  60  is prevented from moving into the hole  91 , the plunger sensor will generate the first electrical output  151 , which indicates improper operation of the solenoid and the plunger. The first and second electrical outputs could be on or off as shown or could be different voltage or current levels. 
     Referring to  FIG.  7   , an example method for determining and/or indicating operation of the solenoid assembly  10  is depicted. As shown at box  302 , the method beings with sensing the presence of the indicator tab  64 , with the plunger sensor  150 . If the plunger sensor  150  does not sense the indicator tab  64  (at box  304 ), the plunger sensor  150  generates the second electrical output. At box  306 , the control system  100  determines proper operation of the solenoid based on the position of the plunger  50  as indicated by the second electrical output from the plunger sensor  150  and the state (e.g., energized or de-energized) of the coil  21 . If the coil  21  is energized (at box  307 ), the control system  100  determines that the plunger  50  is in the proper extended position (at box  308 ). The control system  100  then controls the indicator  160  to thereby indicate proper operation and that coil is energized and the plunger  50  is in the extended position (at box  310 ). 
     If the coil  21  is de-energized (box  311 ), the control system  100  determines that the plunger  50  is improperly in the extended position (at box  312 ) which may be caused by failure of the return spring  70 . The control system  100  then controls the indicator  160  to thereby indicate that the plunger  50  is improperly in the extended position (at box  314 ). 
     The control system  100  could also be configured to permit additional functionality of a machine coupled to the control system  100  when the plunger  50  is properly in the extended position ( FIG.  4   ) and the coil  21  is energized. For example, when the plunger  50  is in the extended position ( FIG.  4   ), the second plunger end  52  engages a brew basket of a coffee machine thereby preventing the brew basket from being removed during operation. The control system  100  can be configured to permit the coffee machine to brew coffee via the brew basket when the plunger  50  is in the extended position ( FIG.  4   ) thereby reducing the risk that the brew basket is not properly placed or to prevent the operator from removing the brew basket before completion of the brewing process thereby decreasing the risk that the hot water burns the operator. 
     Alternatively, if the plunger sensor  152  senses the indicator tab  64  (at box  318 ), the plunger is in the retracted position and the plunger sensor  152  generates the first electrical output which is received by the control system  100 . At box  320 , the control system  100  determines the plunger is retracted. The control system  100  next determines whether the retracted position of the plunger  50  is proper based on the state (e.g., energized or de-energized) of the coil  21 . If the coil  21  is energized (box  321 ), the control system  100  determines (at box  322 ) that the plunger  50  is not in the proper extended position ( FIG.  4   ) and that instead the plunger  50  is in the retracted position ( FIG.  5   ). If the coil  21  is de-energized (box  323 ), the control system  100  determines that the plunger  50  is in the proper retracted position ( FIG.  2   ). The control system  100  can control the indicator  160  to thereby indicate whether the plunger  50  is or is not in the desired retracted position (boxes  326 ,  328 ). When the control system  100  determines that the plunger  50  is not in the extended position ( FIG.  4   ), the control system  100  could prevent functions or operations of the machine coupled to the control system  100 . For example, the control system  100  may prevent the release of hot water when the plunger  50  is not in the extended position and the coil is energized to thereby prevent burning the operator. 
     In certain examples, the control system  100  can be configured to monitor electrical power to the coil  21  and/or determine whether or not electrical power is being applied to the coil  21 . The coil sensor  152  may generate a defined electrical output when the coil  21  is energized, and the control system  100  receives the electrical output from the coil sensor  152  and determines that the coil  21  is energized. 
     Citations to a number of references are made herein. The cited references are incorporated by reference herein in their entireties. In the event that there is an inconsistency between a definition of a term in the specification as compared to a definition of the term in a cited reference, the term should be interpreted based on the definition in the specification. 
     In the present description, certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. The different apparatuses, systems, and method steps described herein may be used alone or in combination with other apparatuses, systems, and methods. It is to be expected that various equivalents, alternatives and modifications are possible within the scope of the appended claims. 
     The functional block diagrams, operational sequences, and flow diagrams provided in the Figures are representative of exemplary architectures, environments, and methodologies for performing novel aspects of the disclosure. While, for purposes of simplicity of explanation, the methodologies included herein may be in the form of a functional diagram, operational sequence, or flow diagram, and may be described as a series of acts, it is to be understood and appreciated that the methodologies are not limited by the order of acts, as some acts may, in accordance therewith, occur in a different order and/or concurrently with other acts from that shown and described herein. For example, those skilled in the art will understand and appreciate that a methodology can alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all acts illustrated in a methodology may be required for a novel implementation. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.