Patent Publication Number: US-10333456-B2

Title: Regulating temperature on an actuator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/803,152, filed on Jul. 20, 2015, and entitled “REGULATING TEMPERATURE ON AN ACTUATOR,” the content of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Linear and rotary actuators are useful devices to operate material handling and/or flow control equipment. This equipment may be found in hazardous areas and/or used to regulate flow of volatile materials (e.g., combustible gasses and liquids). As such, actuators that pair with this equipment must satisfy certain safety requirements including, for example, safety requirements that define a maximum operating temperature for the device. 
     SUMMARY 
     This disclosure relates generally to actuators, with particular discussion about embodiments that are configured to maintain operating temperatures at or below a maximum operating temperature. 
     Some embodiments disclosed herein address problems with actuators that employ electric motors. These embodiments can monitor physical movement of components to detect problematic operation of the electric motor. The components can include a shaft on the electric motor. Should the motor seize or lock, the embodiments can de-energize the electric motor to keep the temperature of the actuator in compliance with safety requirements. 
     In light of the foregoing, the embodiments herein may incorporate elements and features, one or more of the elements and features being interchangeable and/or combinable in various combinations, examples of which may include: 
     An actuator can include a first shaft having a first position and a second position, a motor with a second shaft coupled with the first shaft, a sensor disposed in proximity to the second shaft; and a control processor coupled with the sensor and the motor. The control processor can be configured to receive a signal from the sensor that conveys operating data that relates to rotation of the second shaft use the operating data to identify a fault condition of the motor, and change the motor from a first operating state to a second operating state in response to the fault condition. 
     The actuator can also be configured wherein the sensor is in a position so that the operating data tracks an annular translation of a location on the second shaft. 
     The actuator can also be configured wherein the sensor is configured to rotate with the second shaft. 
     The actuator can also be configured wherein the sensor has a first component and a second component, at least one of which secures to the second shaft and interacts with the other to induce the signal. 
     The actuator can also include a bushing that rotates with the second shaft, wherein the sensor couples with the bushing. 
     The actuator can also be configured wherein the control processor further comprises a switch that couples with the motor, wherein the control processor is configured to change the switch from a first state to a second state in response to the fault condition, and wherein the second state corresponds with the second operating state of the motor. 
     The actuator can also be configured wherein the first operating state is an energized condition and the second operating state is a de-energized condition 
     The actuator can also include a counter coupled with the control processor, wherein the counter is configured to measure a duty cycle, and wherein the control processor is configured to, activate the counter in response to the fault condition and to change the state of the switch from the second state to the first state in response to expiration of the duty cycle. 
     The actuator can also be configured wherein the control processor is further configured to, use the operating data to determine an annular speed for the second shaft, and compare the annular speed to a threshold speed, wherein the fault condition corresponds with a value for the annular speed that deviates from the threshold speed. 
     The actuator can also be configured wherein the signal from the sensor comprises a first signal and a second signal, and wherein the control processor is configured to, determine an elapsed time between the first signal and the second signal and to compare the elapsed time to a rotation threshold, wherein the fault condition corresponds with a value for the elapsed time that deviates from the rotation threshold. 
     An actuator can include a first shaft having a first position and a second position, a motor with a second shaft, a safety device coupled with the motor, the safety device comprising an input/output coupled with the motor and a switch coupled with the input/output, the switch having a first state and a second state, one each that allows an electrical signal to impress on the input/output and that prevents the electrical signal to impress on the input/output. The safety device can be configured to track an annular translation of a location on the second shaft, determine a fault condition of the motor that relates to the annular translation, and change the state of the switch from the first state to the second state in response to the fault condition. 
     The actuator can also include a sensor coupled with the location on the second shaft, wherein the sensor is configured to generate a signal that defines operating data that relates to the annular translation, and wherein the safety device is configured to use the operating data to calculate the annular translation. 
     The actuator can also be configured wherein the annular translation quantifies an annular speed for the location on the second shaft. 
     The actuator can also be configured wherein the signal from the sensor comprises a first signal and a second signal, and wherein the controller is configured to determine an elapsed time between the first signal and the second signal and to compare the elapsed time to a rotation threshold, wherein the fault condition corresponds with a value for the elapsed time that deviates from the rotation threshold. 
     The actuator can also be configured wherein the sensor is configured to rotate with the second shaft. 
     The actuator can also be configured wherein the sensor has a first component and a second component, at least one of which secures to the second shaft and interacts with the other to induce the signal. 
     A method of operating an actuator can include tracking an annular translation for a location on a shaft of a motor, detecting a fault condition of the motor that relates to the annular translation, and changing the motor from an energized condition to a de-energized condition in response to the fault condition. 
     The method can also include changing a switch from a first state to a second state in response to the fault condition, and wherein the second state corresponds with the deenergized condition of the motor. 
     The method can also include starting a counter in response to the fault condition and changing the switch from the second state to the first state in response to the counter reaching a duty cycle value, wherein the second state corresponds with the energized condition of the motor. 
     The method can also include receiving a signal that conveys operating data that relates to the annular translation and using the operating data to calculate the annular translation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is now made briefly to the accompanying drawings, in which: 
         FIG. 1  depicts a schematic, block diagram of an exemplary embodiment of a safety device in use on an example of an actuator; 
         FIG. 2  depicts a schematic, block diagram of an example of the safety device of  FIG. 1 ; 
         FIG. 3  depicts a schematic, block diagram of a control processor for use in the actuator of  FIG. 1 ; 
         FIG. 4  depicts a flow diagram of an exemplary method for operating the actuator of  FIG. 1 ; 
         FIG. 5  depicts a flow diagram of an exemplary method for operating the actuator of  FIG. 1 ; 
         FIG. 6  depicts a perspective view of the front of an example of the actuator of  FIG. 1  in partially-assembled form; 
         FIG. 7  depicts a perspective view of the front of an example of the actuator of  FIG. 6  in partially-exploded form; 
         FIG. 8  depicts a perspective view of the back of an example of the actuator of  FIG. 7  in partially-exploded form; 
         FIG. 9  depicts an elevation view of the cross-section an example of the actuator of  FIG. 6  in partially-assembled form; 
         FIG. 10  depicts a perspective view of the front of an example of a first member of an adapter that can secure to the motive unit of  FIG. 1 ; 
         FIG. 11  depicts a perspective view of the front of an example of a second member of the adapter that can secure to the motive unit of  FIG. 1 ; 
         FIG. 12  depicts an elevation view of the front of an example of the second member of the adapter that can secure to the motive unit of  FIG. 1 ; 
         FIG. 13  depicts an elevation view of the back of an example of the second member of the adapter that can secure to the motive unit of  FIG. 1 ; and 
         FIG. 14  depicts an elevation view of the cross-section of an example of an adapter using the first member and the second member of  FIGS. 10, 11, 12, and 13 . 
     
    
    
     Where applicable like reference characters designate identical or corresponding components and units throughout the several views, which are not to scale unless otherwise indicated. The embodiments disclosed herein may include elements that appear in one or more of the several views or in combinations of the several views. Moreover, methods are exemplary only and can be modified by, for example, reordering, adding, removing, and/or altering the individual stages. 
     DETAILED DESCRIPTION 
     The discussion below describes embodiments of a safety device that can prevent build-up of excess heat on an actuator. These embodiments can be configured to characterize mechanical movement on the actuator. The safety device can use this mechanical movement to detect faulty operation, or a “fault condition,” on an electric motor. Operating the electric motor in the fault condition may result in excess heat that raises the temperature of the electric motor and/or the actuator in general. However, the safety device can modulate power to the electric motor in response to the fault condition to prevent build-up of thermal energy and excess heat. The safety device can keep the temperature of the electric motor and actuator at a safe temperature, as defined by hazardous area threshold levels set out by safety standards and requirements. Other embodiments are within the scope of the disclosed subject matter. 
       FIG. 1  illustrates, schematically, an exemplary embodiment of a safety device  100 . This embodiment can couple with and/or integrate as part of an actuator, generally identified by the numeral  102 . The safety device  100  can include a control processor  104  that couples with a sensor member  106  (also, “sensor  106 ”). The control processor  104  can also couple with a power source  108  that can supply an electrical signal with properties (e.g., direct current (DC), alternating current (AC), voltage, etc.) sufficient to power a motor member  110 . In one implementation, the motor member  110  can translate an actuator member  112  to create useful work. The motor member  110  may include a motive unit  114  that can turn a shaft  116  in response to the electrical signal, as generally indicated by the arrow enumerated  118 . A mechanical coupling  120  can transfer rotation  118  of the shaft  116  to the actuator member  112 . For example, this configuration can move the actuator member  112  to operate a valve assembly (not shown) to open and close a valve. The valve assembly may connect with a process line (e.g., a pipeline) to regulate flow of material (e.g., gasses and liquids). Examples of such process lines are found in chemical facilities, oil &amp; gas production facilities, refineries, and like installations and heavy industries. In one implementation, the actuator  102  may be used in ventilation applications to control airflow dampers. This disclosure recognizes numerous applications that define hazardous areas that require safe handling of operational temperature and related fault conditions on the actuator  102 . 
     The safety device  100  can be configured to maintain temperature of the actuator  102  below certain threshold levels. In some embodiments, the sensor member  106  can generate a signal that conveys operating data that relates to mechanical movement of one or more components on the actuator  102 . This mechanical movement may include translation of the components, as well as vibration, oscillation, and the like. The signal may also convey operating data about other aspects of the operation of the actuator  102 . For example, the signal may identify values for temperature, stress, strain, and like properties of the components on the actuator  102  that may be useful to identify faulty operation and/or fault conditions. 
     The sensor member  106  may embody devices that are sensitive to these properties. These devices may include Hall-effect sensors and giant magnetoresistance (GMR) sensors to detect movement of the shaft  116 . Other devices also could reasonably quantify the movement of components of the actuator  102 . These other devices include, optical sensors, photo-sensitive sensors, capacitive sensors, and like devices that can identify the proximity and/or position of one part relative to another part (e.g., optically-sensitive sensors). 
     The sensor member  106  can be arranged in proximity to the shaft  116  so that the operating data relates to a location on the shaft  116 . Movement of other components might also be suitable including, e.g., movement of actuator member  112 , the mechanical coupling  120 , etc. In one implementation, the control processor  104  can use the operating data from the sensor member  106  to detect a fault condition that indicates that operation of the motive unit  114  is contrary to normal. For example, the control processor  104  may determine a value for the annular translation of a location on the shaft. Changes in this annular translation may signal that the fault condition is present on the motive unit  114 . In response to the fault condition, the control processor  104  can reduce (and/or remove) the electrical signal from the motor member  110  to a level that is insufficient to cause build-up of excess heat on the motive unit  114 . This feature can maintain operating temperatures on the actuator  102  at and/or below threshold levels that can be dangerous in hazardous areas. 
       FIG. 2  depicts a schematic diagram of an example of the safety device  100 . The control processor  104  can have one or more input/outputs (e.g., a first input/output  122  and a second input/output  124 ). The input/outputs  122 ,  124  can couple the control processor  104  with the motor member  110  and the power source  108 , respectively. The control processor  104  can also couple with other sensors (e.g., a thermal sensor  126  and a travel sensor  128 ). The thermal sensor  126  can generate a signal that conveys operating data that reflect a measured temperature on the actuator  102 . Examples of the thermal sensor  126  include thermostatic limit switches, thermocouples, thermistors, or like elements, one or more of which can mount inside of the motor member  110  or other part of the actuator  102  as desired or as set forth by design specifications. The travel sensor  128  can generate a signal that conveys operating data that reflect a position (e.g., a first position and a second position) of the actuator member  112 . This operating data may be helpful to identify that the actuator member  112  has reached the outer extent of its travel. 
     The sensor member  106  can be configured to reside in proximity and/or proximate the shaft  116 . In some embodiments, the sensor member  106  can have one or more sensor components (e.g., a first sensor component  130  and a second sensor component  132 ). Examples of the sensor components  130 ,  132  can embody various types of sensors including proximity sensors, optical sensors, photo-senstive sensors, capacitive sensors, and like devices that can identify the proximity and/or position of one part relative to another part. In one implementation, the sensor components  130 ,  132  may reside proximate the shaft  116 . For proximity sensors, the sensor components  130 ,  132  may correspond with a transmitter and a receiver, wherein the transmitter generates a radiative output (e.g., magnetic field, light, etc.) to induce the signal in the transmitter. In one implementation, the first sensor component  130  may secure to the shaft  116  so that as the shaft  116  rotates, the first sensor component  130  changes position relative to the second sensor component  132 . A mounting member  134  may be used to affix the first sensor component  130  to the shaft  116 . Examples of the mounting member  134  may embody a bushing, collar, or like implement. The mounting member  134  may have a body that at least partially circumscribes the shaft  116 . The body may be made of plastic or non-metallic material to avoid interfering with operation of the sensor components  130 ,  132 . The body can be molded to incorporate the first sensor component  130  and have apertures configured to receive fasteners (e.g., screws, bolts, etc.). When assembled, these fasteners can lock the mounting member  134  into position on the shaft  116 , although more permanent placement of the mounting member  134  may use other techniques (e.g., welding, adhesives, etc.). 
     The second sensor component  132  can couple with structure on the actuator  102  to affix its position relative to the first sensor component  130 . This structure may include a housing that encloses parts of the motor member  110 . A bracket may be used to receive the second sensor component  132 . This bracket may couple with the housing using, e.g., fasteners, welds, adhesives, and the like. In lieu of the bracket, the housing may incorporate features to affix the second sensor component  132  in position relative to the first sensor component  130 . This position can be in close proximity to the first sensor component  130  to allow the sensor components  130 ,  132  to interact with one another. In one implementation, the signal from the sensor member  106  corresponds with movement of the first sensor component  130  relative the second sensor component  132 . The signal may define a change in voltage from a first (or low) level to a second (or high) level. 
     Some embodiments can detect various fault conditions using the signals from the sensor member  106 . Broadly, the fault conditions may indicate changes in operation of the motive unit  114  that can, or are likely to, increase temperature in excess of certain safety thresholds. One exemplary change in operation may reflect seizing of the motive unit  114  that prevents rotation of the shaft. In another change in operation, the shaft may rotate at one or more speeds that are different (e.g., slower) than the speed(s) related to normal operation. Other operation that may indicate the increase in temperature may include jerking and/or halting rotation in one or more annular directions, oscillation and/or annular cycling of the shaft between two annular positions, and the like. 
     During operation, the control processor  104  can change the state of the first input/output  122  in response to the fault condition. These states may correspond to different operating conditions of the motive unit  114  including, for example, conditions that reflect the motive unit  114  is on, the motive unit  114  is off, the motive unit  114  travels at different speeds (e.g., slower, faster, etc.), and/or some other alternation in the operation of the motive unit  114 . The states can include a first state (also, “power on state”) and a second state (also, “power off state”), one each that can reflect the presence or absence of the electrical signal at the first input/output  122 . In the first state, the electrical signal impresses on the first input/output  122 . The first state corresponds with the motive unit  114  in the energized condition. In the second state, the electrical signal is absent (and/or reduced) from the first input/output  122 . The second state corresponds with the motive unit  114  in the de-energized condition. Absent the electrical signal, the motive unit  114  may fail to build-up excess heat that might damage the windings found in AC and/or DC electric motors (and like devices). In some embodiments, the control processor  104  can modulate the electrical signal to the first input/output  122  according to a duty cycle. This feature can change the first input/output  122  between the first state and the second state, which corresponds with the motive unit  114  changing between the energized condition and the de-energized condition. Such operation may last until the fault condition is cleared and/or the actuator  102  is repaired or decommissioned from its present application. 
       FIG. 3  depicts a schematic diagram of an example of the control processor  104 . This example can include a processor member  136  and a storage memory  138 , which may be a separate component or integrate with the processor member  136  as part of an integrated processor  140 . This disclosure contemplates that some embodiments may utilize a substrate (e.g., a printed circuit board) to support the members  136 ,  138 ,  140  and other discrete elements. The storage memory  138  may include one or more executable instructions  142  in the form of computer-implemented programs (e.g., software, firmware, etc.). In some embodiments, the integrated processor  140  can include a clock  144  that accurately measures real and/or current time. The clock  144  may be capable of non-volatile operation in absence of power. Separately, the integrated processor  140  may include one or more counters (e.g., a first counter  146 ). The counters  146  can be used to control a power-off state duration, which enforces the operational duty cycle (noted above) as well as duration of the fault condition that persists on the motive unit  114 , as noted more below. In one example, the counters  146  can also measure an elapsed time between signals from the sensor member  106  ( FIG. 2 ). This feature may be effective to track the annular translation of the shaft  116 . 
     As also shown in  FIG. 3 , some embodiments can include a relay member  148  with a relay driver  150  that operates a relay switch  152 . The relay driver  150  may receive command signals from the integrated processor  140 . The relay switch  152  can be interposed between the input/outputs  122 ,  124 . In this way, operation of the relay switch  152  between a first state and a second state can result in the power on state and the power off state of the input/outputs  122 ,  124 . Examples of the relay member  148  may be implemented as an electro-mechanical relay, transistors, triacs, SCRs, and combinations and derivations thereof. In one example, the control processor  104  can also have a power supply  154  with one or more members (e.g., a first power supply member  156  and a second power supply member  158 ). The first power supply member  156  can couple with the second input/output  124  to receive the electrical signal from the power source  108 . In use, the first power supply member  156  can embody a DC supply that can convert the electrical signal to appropriate form for use by the components (e.g., the integrated processor  140 , the relay driver  150 , etc.). The second power supply member  158  can embody a battery, a capacitor, or like discrete element (and/or combination of discrete elements). Such discrete element(s) can couple with the integrated processor  140  to provide back-up power in lieu of the converted electrical signal from the first power supply member  156 . In this way, the integrated processor  140  can maintain nonvolatile operation of one or more functions and/or functional elements including, for example, the clock  144  and the counters  146 . 
       FIGS. 4 and 5  illustrate flow diagrams for exemplary embodiments of a method  200  for operating the safety device  100  to regulate temperature on the actuator  102 . These diagrams outline stages that may embody executable instructions for one or more computer-implemented methods and/or programs. The executable instructions may be stored on the storage memory  138  and/or otherwise accessible to processor member  136 . For example, the integrated processor  140  may be configured to execute these executable instructions to regulate the electrical signal in a way that prevents thermal overload detrimental to operation of the actuator  102 . The stages in these methods can be altered, combined, omitted, and/or rearranged in some embodiments. 
     In  FIG. 4 , the method  200  can include, at stage  202 , receiving a first signal from the sensor member  106  that conveys operating data that relates to rotation of the shaft  116 . The method  200  can also include, at stage  204 , using the operating data to detect the fault condition on the motor. In one implementation, the fault condition may relate to the annular translation of the shaft  116 . For example, the method  200  may include, at stage  206 , using the operating data to determine a value for an annular translation of a location on the shaft and, at stage  208 , comparing the value for the annular translation to a threshold criteria and, at  210 , detecting the fault condition. If the value does not satisfy the threshold criteria, then the method  200  can continue to track movement of the shaft at stage  202 . On the other hand, if the value does satisfy the threshold criteria, then the method  200  can include, at stage  212 , generating an output to change the motor from the energized condition to the de-energized condition in response to the fault condition. In other implementations, the output may also slow the motor (e.g., by adjusting power input to the motor), apply a braking mechanism, introduce a cooling mechanism (e.g., fluid) to the motor, and/or cause some type of functionality that will help to modulate heat and thermal build-up on the motor, as desired. 
     At stage  202 , the method  200  can receive operating data that relates directly to mechanical movement of the shaft  116 . The first signal can arise from interactions between the sensor components  130 ,  132  as discussed herein. The operating data that relates to the first signal may be helpful to track the movement or annular translation of a location on the shaft  116 . In one implementation, the second sensor component  132  can generate one or more pulses whenever the first sensor component  130  comes in close proximity to the second sensor component  132 . This pulse may indicate different levels (e.g., a high level or a low level) of voltage at the control processor  104 . 
     At stage  204 , the method  200  can use the operating data to detect the fault condition. The fault condition can indicate that the motive unit  114  is stalled and/or locked. These conditions can prevent rotation of the shaft  116 . In turn, the windings of the motive unit  114  will generate thermal energy under constant power. This feature can increase temperatures on the actuator  102  that are above and/or outside acceptable operating limits. 
     At stage  206 , the method  200  can determine a value for the annular translation of the location on the shaft  116 . Examples of this value may relate to displacement and/or annular speed for the “tracked” location. In one implementation, the method  200  may include one or more stages for tracking the annular translation of the location. These stages utilize the signals from the sensor  106 . For example, the method  200  may include one or more stages for determining an elapsed time between a first pulse (or first signal) and a second pulse (or second signal) from the second sensor component  132 . These stages may also include stages for activating a counter (e.g., the counters  146 ) and de-activating the counter in response to the first pulse and the second pulse, respectively. Use of the counter can measure the elapsed time between pulses. The method  200  may also include one or more stages for storing and/or retaining the value of the counter in, e.g., storage memory  138 . The method  200  can also include stages for accessing the storage memory  138  to retrieve the value (and/or other operating data, where applicable). In some embodiments, the method  200  may include one or more stages for calculating the annular speed over one complete rotation of the shaft  116 . These calculations may take into consideration certain variables including the elapsed time and one or more dimensions (e.g., diameter) of the shaft  116 . 
     At stage  208 , the method  200  can compare the value for the annular translation to the threshold criteria. Examples of the threshold criteria may identify an allowable rotation period, an allowable annular speed, or like identifier that quantifies the rotation of the location on the shaft  116 . Values for the identifiers may be fixed or pre-determined as part of factory set-up or calibration. These values may be stored in the storage memory  138 . Such values may be amenable to updates via user interface and/or upgrades to the executable instructions. In one implementation, the method  200  may include one or more stages for comparing the elapsed time between pulses to a rotation threshold. Examples of the rotation threshold may identify a maximum value and/or a minimum value for the time required between the pulses. 
     At stage  210 , the method  200  can determine whether the value for the annular translation satisfies the threshold criteria. The method  200  may include one or more stages for identifying the relative position (e.g., greater than, less than, equal to, not equal to, etc.) between the value and the threshold criteria. When the motive unit  114  is in the fault condition, the relative position may indicate that the elapsed time between pulses (or annular speed of the location of the shaft  116 ) meets and/or exceeds the maximum allowable rotation period or annular speed. Such operation may indicate the fault condition on the motive unit  114 . On the other hand, the relative position may indicate that the elapsed time between pulses (or annular speed of the location of the shaft  116 ) is less than the maximum allowable rotation period or annular speed. This condition may indicate normal operation of the motive unit  114  and, thus, the method  200  will not detect the fault condition. 
     At stage  212 , the method  200  can generate the command signal. Examples of the command signal can instruct the relay driver  150  to change the relay member  148  between the first state and the second state. The change in state can prevent the electrical signal from the first input/output  122 . In turn, operation of the motive unit  114  will change to prevent and/or pre-empt build-up of thermal energy. These changes may alter operation of the motor, e.g., from the energized condition to the de-energized condition. The de-energized condition may correspond with no electrical signal impinging on the windings (or like components). As noted above, some embodiments herein may affect other alterations to the operation of the motive unit  114 . 
       FIG. 5  illustrates a flow diagram of an example of the method  200  that can modulate the motor member  110  between the de-energized condition and the energized condition. This example is helpful to identify if, at all, the fault condition is cleared and/or the motor assumes normal operation. 
     The method  200  can include, at stage  214 , initializing a second counter. The second counter can correspond to the duty cycle that measures a period of time between the energized condition and the de-energized condition of the motive unit  114 . The method  200  can also include, at stage  216 , comparing the second counter to a duty cycle threshold, which may be pre-scribed during the factory set-up or calibration noted above. The method  200  can also include, at stage  218 , determining when the duty cycle satisfies the duty cycle threshold. This stage may quantify the relative position (e.g., greater than, less than, equal to, not equal to, etc.) between the value of the counter for the duty cycle and the duty cycle threshold. Before the duty cycle expires and/or satisfies the duty cycle threshold, the method  200  can include, at stage  220 , maintaining the motor in the de-energized condition. On the other hand, when the duty cycle expires and/or satisfies the duty cycle threshold, the method  200  can continue, at stage  222 , receiving a second signal that that relates to a measured temperature on the actuator  102 . Examples of the measured temperature may correspond with the temperature of motor member  110 , although other temperatures may be appropriate to characterize the thermal condition of the actuator  102  relative to the safety standards. 
     The method  200  can also include, at stage  224 , comparing the measured temperature to a threshold temperature and, at stage  226 , determining whether the measured temperature satisfies the threshold temperature. If affirmative, the method  200  can continue, at stage  214 , to restart the counter. On the other hand, if the temperature does not satisfy the threshold temperature, then the method  200  can include, at step  228 , receiving a third signal that corresponds with a measured travel of the actuator  102 . The method  200  can also include, at stage  230 , comparing the measured travel to a threshold travel, and at stage  232 , determining whether the measured travel satisfies the threshold travel. The threshold travel for linear actuators may define a maximum position and/or a minimum position for the actuator member  112 . In one implementation, if the actuator  102  is at the maximum position and/or the minimum position, the method  200  can include, at stage  234 , awaiting additional operating instructions. When the measured travel is between the maximum position and the minimum position, the method  200  can continue, at stage  236 , generating an output to change the motor from the de-energized condition to the energized condition and returning in one implementation to stage  202  ( FIG. 4 ) to monitor operation of the motor member  110 . 
     The discussion now turns to an implementation of the safety device  100 . More specifically,  FIGS. 6, 7, 8, and 9  illustrate various views of an example of the actuator  102 . This example can generate rotary movement. In the views, the actuator  102  is shown with some members removed to enhance the clarity of the drawings and discussion herein.  FIG. 6  illustrates a perspective view of the front of the actuator  102 .  FIG. 7  illustrates the actuator  102  of  FIG. 6  in partially exploded form.  FIG. 8  illustrates a perspective view of the back of the actuator  102  in partially-exploded form.  FIG. 9  depicts an elevation view of the cross-section of the actuator  102  taken at line  9 - 9  of  FIG. 6 . 
     Referring first to  FIG. 6 , the housing of the actuator  102  can include a cover assembly that forms a protective enclosure to secure the components of the device. The housing can have one or more cover members (e.g., first cover member  160 ), each being constructed to interface with one or more of the others to form the protective enclosure. The cover members  160  may be made of materials that are resistant to corrosion and deterioration from the ambient environment. A bushing  162  may insert into the cover members  160  to receive a shaft  164  that operates as the actuator member  112  in the actuator  102 . The bushing  162  may be arranged with bearings and/or lubricants to minimize rotary friction of the shaft  164  relative to the cover members  160 . The shaft  164  has an end that extends through the cover members  160 . This end can couple with other collateral parts that are required and/or designated to move to create useful work. In this way, rotation of the shaft  164  will realize movement in the collateral parts, e.g., to open and close a valve (not shown). 
       FIG. 7  shows the front of the actuator  102  in partially exploded form. The housing may enclose a plate member  166  with features to receive, support, and fasten various members of the actuator  102 . The plate member  166  can be a generally flat and/or planar sheet of metal with features (e.g., threaded and non-threaded openings). The members of the actuator  102  may include a small electric (DC or AC) motor  168 . In one implementation, the electric motor  168  can rotate a geared member  170  that extends through the plate member  166 . Although not shown, the actuator  102  may include a transmission assembly (e.g., one or more coupled gears) that couples the geared member  170  to the shaft  164 . The sensor member  106  may include an adapter  172  that is moveable relative to a switch  174 . In relation to the prior discussion of  FIGS. 1, 2, and 3 , the adapter  172  and the switch  174  operate as the first sensor component  130  and the second sensor component  132 , respectively. The switch  174  can affix to the plate member  166  using one or more suitably fashioned fasteners (e.g., screws). The adapter  172  can couple with the motor  168 . 
       FIG. 8  shows the back of the actuator  102  in partially exploded form. The control processor  104  may reside on a bracket  176  that affixes to the plate member  166 . Fasteners with appropriate insulation may be useful to isolate the control processor  104  from electric shocks and/or related static discharge. The motor  168  may secure to a motor mount  178  in lieu of directly coupling with the plate member  166 . In one implementation, the motor mount  178  can include peripheral openings  180  to allow fasteners (e.g., screws) to mate with corresponding threaded openings on the motor  168 . The motor mount  178  may also be configured to interface with the plate member  166  in order to reduce and/or dampen vibrations and other physical disturbances that can frustrate operation of the actuator  102 . Located in front of the plate member  166 , the adapter  172  may include a first body  182 , a second body  184 , and one or more magnets (e.g., a first magnet  186  and a second magnet  188 ). The magnets  186 ,  188  can couple with the second body  184 . In use, operation of the motor  168  will change the position of the magnets  186 ,  188  relative to the switch  174  ( FIG. 7 ) to modulate the signals that are useful to determine the annular translation of the shaft  116 , as noted herein. 
     The cross-section of  FIG. 9  illustrates the parts of the actuator  102  shown in  FIG. 8  in assembled form. Moving from right to left in the diagram, the motor  168  inserts into a bore  190  on the motor mount  178 . The geared member  170  inserts onto the shaft  116 . The first body  182  can insert onto the geared member  170 . One or more set screws or like implements may be used to securely affix the geared member  170  to the shaft  116  and the first body  182 . This configuration can avoid slippage and/or relative movement that can, at least, introduce error into the calculated values for the annular translation of the shaft  116 . As also shown in  FIG. 9 , the bodies  182 ,  184  can couple with one another at an interface  192 . Examples of the interface  192  can prevent relative axial, longitudinal, and rotation movement between the bodies  182 ,  184 . For axial and longitudinal movement, the interface  192  can form a snap-fit to connect the bodies  182 ,  184 . The interface  192  may also be useful to retain the magnets  186 ,  188  ( FIG. 8 ) inside of the second body  184 . 
     The discussion now follows with examples of the construction and implementation of the adapter  172 .  FIG. 10  depicts a perspective view of the front of an example of a first adapter member  300 .  FIGS. 11, 12, and 13  depict various views of an example of a second adapter member  400 .  FIG. 14  depicts an elevation view of the cross-section section of an example of the adapter member  500  with the first adapter member  300  coupled with the second adapter member  400 . 
       FIG. 10  illustrates an example of a first adapter member  300 . This example may have a first body  302  in the form of, generally, an elongated cylinder with a central aperture  304 . The first body  302  may be molded or cast from composites (e.g., plastics), although metals and/like hardened materials may be used to form the features discussed herein. Moving from the back  306  to the front  308  of the first body  302 , the first body  302  can include a first section  310  in which the cylinder has a first diameter. The first section  310  couples with a first side  312  of a flange portion  314 . In the flange portion  314 , the cylinder may have a second diameter that is larger than the first diameter. On the second side  316  of the flange portion  314 , the first body  302  may include a first interface member  318  with a pair of arcuate surfaces (e.g., a first arcuate surface  320  and a second arcuate surface  322 ). The arcuate surfaces  320 ,  322  may extend from the flange portion  314  to an interface shoulder  324  that is spaced apart from the flange portion to form an interface gap  326 . The cylinder may have a third diameter at the interface shoulder  324  that is larger than the diameter of the cylinder as measured between the arcuate surfaces  320 ,  322 . In one example, the arcuate surfaces  320 ,  322  may partially circumscribe the central aperture  304 , terminating at a pair of flat, radial surfaces (e.g., a first radial surface  328  and a second radial surface  330 ), which are spaced apart from one other on either side of the central aperture  304 . 
       FIGS. 11, 12, and 13  illustrate an example of the second adapter member  400 . This example has a second body  402  in the form of a thin, round disc with a center axis  404 . The second body  402  may have a key-way opening  406  that is disposed centrally in the disc. The key-way opening  406  may have a profile that defines a pair of arcuate ends (e.g., a first arcuate end  408  and a second arcuate end  410 ). The profile may also include a pair of elongated sides (e.g., a first elongated side  412  and a second elongated side  414 ) that connect to the arcuate ends  408 ,  410 . The sides  412 ,  414  may each feature a radial portion  416  where the profile of the key-way opening  406  diverges radially away from the center axis  404  of the disc. On the front, as shown in the front view of  FIG. 12 , the key-way opening  406  can form a pair of surfaces (e.g., a first surface  418  and a second surface  420 ) that are recessed from a front surface  422  of the disc. On the back, as shown in  FIG. 13 , the second body  402  can have back surface  424  with a pair of apertures (e.g., a first aperture  426  and a second aperture  428 ). The apertures  426 ,  428  can be circular, although the shape and depth may be selected to accommodate the magnets  186 ,  188  ( FIG. 8 ). 
       FIG. 14  illustrates an example of an adapter  500  that includes the adapter members  300 ,  400 . In one example, first adapter member  300  can insert into the key-way opening  406  from the back to the front of the second body  402  (also, from right to left in the diagram of  FIG. 14 ). The interface gap  326  is devised so that the opposing surfaces of the flange portion  314  and the interface shoulder  324  contact the second adapter member  400  at the surfaces  418 ,  420  and the back surface  424 , respectively. This configuration secures the first adapter member  300  in the recessed key-way opening  406  to prevent relative movement with respect to the second adapter member  400 . As noted above, the flange portion  314  extends radially outwardly from the center axis  404  to overlap with the apertures  426 ,  428  ( FIG. 13 ). This feature may secure the magnets  186 ,  188  ( FIG. 8 ) in the second body  402 . The entire adapter  500  can fit onto the geared member  170  ( FIG. 9 ) to rotate the magnets  186 ,  188  ( FIG. 8 ) in response to operation of the motor  168  ( FIG. 9 ). 
     In light of the foregoing discussion, the disclosed subject matter describes a safety device that can regulate temperature of an actuator. The embodiments can detect faulty operation of the actuator, often using operating data that relates directly to movement (e.g., annular translation) of a shaft of an electric motor that translates the actuating member to do useful work. A technical effect is to generate an output that corresponds with a de-energized state for the electric motor. This de-energized state can prevent the build-up of excess heat that can increase the temperature on the actuator in excess of acceptable levels for use of the actuator in hazardous areas and/or in connection with flammable, combustible materials. 
     As used herein, an element or function recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or functions, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” should not be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. To the extent that the claims recite “at least one of X and Y” (or any similar phrase) this is intended to include “one or both of X and Y” and is not limited to “at least one X and at least one Y.” 
     This written description uses examples to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the embodiments 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 language of the claims.