The present disclosure relates to precision level sensors, and more particularly, to level sensors which interact with controllers to accurately monitor and/or control system behavior in, e.g., steam heated cooking devices.
Sensors are used to monitor the relative amount of a fluid within a fluid reservoir, such as the water level in a steam cooker designed to quickly heat and/or cook food in commercial food service settings. In order to heat and/or cook food in a steam cooker, water is heated until it changes phase to become steam. The steam is then circulated through the cooker using a fan or other circulation mechanism to allow the steam to contact the food and increase the temperature of the food. As the steam is circulated, some may escape the steam cooker such that water from the reservoir is consumed. In order to maintain proper functioning of the steamer and avoid over-temperature conditions, the reservoir must be periodically replenished with fluid.
To this end, some steam cookers use conductance probes to sense water level in a water reservoir typically located at the bottom of the steamer, and may control an electric solenoid valve for the selective addition of water when a “low water” condition is detected by a lack of conductance in the probe. However, such conductance probes ar submersed in a pool of liquid water in the water reservoir below the steam chamber, and are therefore subject to exposure to food particles, grease, and other impurities in the steamer water. In some cases, dirty conductance probes may falsely indicate the presence of water in an empty steamer. Alternately, dirty conductance probes can also falsely indicate the absence of water and cause an overfill condition. Consequently, conductance probes require regular cleaning. Steam cookers may also utilize a magnetic float and reed switch to sense water overfill conditions. Each of these sensors provides a digital on/off signal corresponding to a single discrete water level. The only information that can be inferred from this discrete signal is the presence or absence of water at that level.
Alternative position-sensing technologies are known to be used in other contexts. For example, encoders and servo motors may be used to provide an indication of position of one part relative to another across a range of motion, and are commonly used in robotics applications, for example. While these position-sensing technologies are effective, they can be costly and prone to failure in harsh environments.
Hall effect sensors may also be used to monitor for the presence or absence of a magnet in some motion-sensing applications such as air cylinders. Magnets used with such sensors include axially magnetized magnets, which have poles at respective axial ends along a longitudinal axis of an elongate magnet, and radially magnetized magnets, which have poles at the interior surface of a generally tubular magnet (e.g., a surface facing the longitudinal axis) and the exterior surface (e.g., a surface spaced radially away from the interior surface and facing outwardly away from longitudinal axis). Such Hall effect sensors can be appropriate for harsh environments, e.g., for air cylinders rated for use in such environments, but have typically been used only to provide a digital on/off signal.
It has, however, been noted that a Hall effect sensor can work in conjunction with a radially magnetized magnet to provide an analog output signal over a certain range of travel. As shown in
The present disclosure provides an improved fluid level sensor including a radially magnetized magnet integrated into a float, and a Hall sensor adapted to monitor the magnet field emitted from the magnet. This arrangement provides a continuously variable signal across a range of travel, such that a controller receiving the signal can produce precise fluid level measurements and detect operational states of an associated device based on fluid behavior. In addition, the present fluid level sensor is suitable for use in harsh service environments, both because it is physically resilient to fouling, and because the controller is capable of detecting fouling by sensor behavior. In the context of a steam cooker, the present fluid level sensor can also sense low-water, overfill and fouling conditions, while remaining relatively insensitive to food residue, water scale buildup, corrosion and foaming.
In one form thereof, the present invention provides a level sensing assembly including: a float body that is buoyant on a quantity of fluid; a radially magnetized magnet having an interior bore with a first magnet pole and an exterior surface radially opposite the interior bore, the exterior surface having a second magnet pole opposite the first magnet pole; a Hall effect sensor sized to be translated axially with respect to the radially magnetized magnet along a range of axial travel within the interior bore of the radially magnetized magnet to produce an output, the magnitude of the output varying substantially linearly with respect to a varying axial position of the Hall effect sensor along the range of axial travel; and a controller programmed to receive the output from the Hall effect sensor and determine a level of a fluid corresponding to the axial position of the Hall effect sensor along the range of axial travel.
In another form thereof, the present invention provides a steam cooker including: a cabinet having a cooking chamber accessible through a door, the cabinet substantially sealed when the door is closed; a reservoir in fluid communication with the cooking chamber; and a level sensing assembly. The level sensing assembly includes: a float body buoyant on a quantity of water, the float body positioned within the reservoir, a radially magnetized magnet having an interior bore with a first magnet pole and an exterior surface radially opposite the interior bore, the exterior surface having a second magnet pole opposite the first magnet pole; and a Hall effect sensor sized to be translated axially with respect to the radially magnetized magnet along a range of axial travel within the interior bore of the radially magnetized magnet to produce an output, the magnitude of the output varying substantially linearly with respect to a varying axial position of the Hall effect sensor along the range of axial travel.
In yet another form thereof, the present invention provides a method of assessing the operational state of a fluid-interactive appliance, the method including: receiving an analog signal from a Hall effect sensor disposed within an inner bore of a radially magnetized magnet, the magnitude of the analog signal varying substantially linearly with respect to a varying axial position of the Hall effect sensor along a range of axial travel within the inner bore of the radially magnetized magnet, the radially magnetized magnet fixed to a float that is buoyant on a fluid in a reservoir; processing the analog signal to determine the axial position of the radially magnetized magnet and the float relative to the Hall effect sensor; and determining a level of a fluid within the reservoir from the axial position of the float as a function of the substantially linear analog signal.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become mom apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrates embodiments of the invention, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention in any manner.
Commercial and residential food processing devices such as steam cooker 10 shown in
Level sensing assembly 40 may be used in conjunction with any number of different devices, including food processing devices such as coffee makers and other fluid-interactive devices such as humidifiers. For purposes of the present disclosure, level sensing assembly 40 and its associated structures is described in detail herein in the context of steam cooker 10 (
Turning now to
The float body 52 includes a sealed interior volume 54 contained and bounded by lower portion 52A, upper portion 52B, and center tube 55 which forms the cylindrical inner wall of float body 52. The sealed interior volume 54 contains magnet 44, retainers 50 and a volume of air space calculated to provide a desired level of buoyancy in fluid F given the weight of float assembly 42. In the illustrated embodiment of
As discussed in further detail below, Hall effect sensor 48 is axially positioned within the hollow bore or cavity of probe 46 at a position to coincide with the axial extent of magnet 44 through its expected range of axial travel. Stated another way, some portion of magnet 44 at all times radially (relative to the longitudinal axis of probe 46) surrounds Hall effect sensor 48 throughout the expected range of axial travel (along the longitudinal axis of probe 46). This allows for the production of an output signal from sensor 48 that is substantially linear throughout the range of axial travel. More particularly, sensor 48 outputs an analog voltage signal, the magnitude of which varies substantially linearly with respect to a varying axial position of magnet 44 relative to sensor 48 along the range of axial travel of magnet 44. For purposes of the present disclosure, “substantially linear” means a signal which defines a linear regression with an R-value at least 0.80. This linear voltage signal provides continuous information to controller 106 (
In an exemplary embodiment, retainers 50 are substantially equal in axial size, and/or spaced appropriately along center tube 55, to hold magnet 44 in an axially centered position within interior volume 54 of float body 52. This allows the same linear relationship to exist between the analog voltage curve of sensor 48 and the axial position of float assembly 42 on probe 46, regardless of the orientation of float assembly 42. That is, float assembly 42 may be installed “right side up” with lower portion 52A of float body below upper portion 52B, or “upside down” with portion 52B below portion 52A, with no change in the quality or nature of the signal output generated by the electromagnetic interaction between magnet 44 and sensor 48. Moreover, this interchangeability of orientation of float assembly 42 is also enabled by the radial magnetization of magnet 44, in which a first magnet pole 58 (i.e., one or “north” or “south”) is located at the interior bore of magnet 44 (
Magnet 44 may be made as a single, monolithic cylinder or a series of shorter cylindrical magnet components joined or bonded to one another to make a longer cylinder having the desired length. In an exemplary embodiment, retainers 50 are located on center tube 55 between the upper and lower interior walls of float body 52 and magnet 44. For the illustrated application of level sensor 40 in steam cooker 10, magnet 44 may have an outer diameter of 0.787 inches, an inner diameter of 0.531 inches, and an overall axial length of 0.945 inches arising from a stack of six magnet components. For example, each of the six magnet components may have an individual axial length of about 0.158 inches, which combines to create the overall axial length of 0.945 inches for magnet 44. Whether monolithic or component-based, this length and configuration of magnet 44 yields a linear analog signal receivable by Hall effect sensor 48 over one inch of axial travel along probe 46. A larger magnet 44, such as one having an outer diameter of 1.09 inches, an inner diameter of 0.74 inches, and an overall length of 1.31 inches, can be used for a longer effective travel with a substantially linear analog signal of about 1.25 inches.
1. Steam Cooker Application.
As noted above, level sensor assembly 40 may be applied to any fluid reservoir 26 where data pertaining to the level of the fluid, and various changes in such level, is desired. In one exemplary application, fluid reservoir 26 is located within steam cooker 10, shown in
Steam cooker 10 is includes door 12 mounted to a cabinet, a handle 14 mounted to door 12, and control panel 102. The cabinet of steam cooker is substantially sealed when door 12 is closed, with intentional penetrations for controlled steam and/or pressure release, water ingress for refill, and the like as described in greater detail below. In order to access the interior cooking chamber 20 of steam cooker 10, door 12 may be opened by actuation of handle 14, which allows door 12 to pivot about hinges 18. Wire rails 22 are positioned within cooking chamber 20 of steam cooker 10, as shown in the cross-sectional views of
With food positioned within cooking chamber 20, door 12 may be closed and steam cooker 10 activated, such as by setting a desired temperature and/or by turning on steam cooker 10 via user manipulation of control panel 102. Specifically, when steam cooker 10 is activated, heaters 24 positioned below water reservoir 26 (
One exemplary steam cooker 10 which can be used with level sensor assembly 40 the Evolution Steamer available from Accutemp Products of Fort Wayne, Ind. One example of an Evolution Steamer is described in a document submitted on even date herewith in an Information Disclosure Statement entitled EVOLUTION STEAMER OWNERS MANUAL, the entire disclosure of which is hereby expressly incorporated herein by reference.
In some applications, steam cooker 10 is connected to an external water supply via water port 34 as best seen in
Referring to
In one exemplary embodiment, the effective maximum depth of water within reservoir 26 of steam cooker 10 may be between 1.5 inches and 2.5 inches, with a 1-inch range of axial travel of float assembly 42 representing the difference between an operationally “empty” reservoir 26 and an operationally “full” reservoir 26. For example, a total water depth between 1.1 inches and 1.4 inches depth may be considered operationally empty, because it corresponds to a water level that is below the minimum for operation of heaters 24. In this exemplary application, float body 52 may be a cylindrical float with a diameter of about 2.5 inches and a height of about 1.9 inches, while magnet 44 contained therein may have a weight of about 43 grams. In this configuration, a water level of about 1.1 inches will cause float assembly 42 to start floating on the surface of fluid F (
The use of level sensor assembly 40 in conjunction with steam cooker 10 provides high reliability with minimal cleaning requirements, and therefore provides longer and more reliable service intervals as compared to existing designs (e.g., conductivity sensors exposed to fluid F within reservoir 26). In addition, level sensor assembly 40 provides analog signals which can be processed via controller 106 and computing system 100 to precisely determine the level of fluid F, as well the change of such level and trends indicative of operational states of steam cooker 10, as described in further detail below. This enhanced functionality can be used, for example to compensate for variation in local water pressure when undertaking a “fill” operation by directly measuring change in water level from incoming water. Expanded messaging via display 103 of user interface 102 can also assist operators in using, maintaining and assessing the function of steam cooker 10. These enhanced functions can be achieved at reduced cost and complexity, because level sensor assembly 40 may perform the function of several sensors from existing designs such as a high-level sensor, one or more low-level sensors, and conductivity probes.
2. Control System.
Computing system 100, shown in
Referring still to
For other embodiments, such as those in which steam cooker 10 is part of a larger system, computing system 100 may be a general purpose computer or a stand-alone computing device such as a desktop computer, a laptop computer, or a tablet computer. Although computing system 100 is illustrated as a single computing system, it should be understood that multiple computing systems may be used together, such as over a network or other methods of transferring data. Where steam cooker 10 is part of a larger network of systems, software 108 may further include communications software, if computing system 100 has access to a network, such as a local area network, a public switched network (e.g., the Internet), a CAN network, any type of wired network, or any type of wireless network.
Software 108 of memory 104 also includes operating system software. An exemplary operating system software includes commercially available software packages commonly used for industrial microprocessor computers. Where steam cooker 10 is part of a larger network of systems, software 108 may further include communications software, if computing system 100 has access to a network, such as a local area network, a public switched network (e.g., the Internet), a CAN network, any type of wired network, of any type of wireless network.
Referring to
Turning now to
If voltage signal 200 exceeds maximum threshold 204, computing system 100 may determine that fluid F contained in reservoir 26 is above its maximum fill level. In this operational state, controller 106 may be programmed to disable heaters 24, close water valve 38 in order to prevent any further ingress of water into reservoir 26, illuminate a high water light or other signal at display 103, and/or activate an alarm. This operational state indicates an “overfill shutdown” condition, which may be remedied by manual or automatic removal of sufficient fluid F from reservoir 26. In one exemplary embodiment, the maximum threshold is about 3.6 V. For purposes of the present disclosure, all voltages refer to a nominal DC voltage.
Similarly, if voltage signal 200 falls below minimum threshold 202, computing system 100 may determine that fluid F contained in reservoir 26 is below its minimum fill level. In this operational state, controller 106 may be programmed to take one or more corrective actions, such as disabling heaters 24, opening water valve 38 in order to allow water to flow into reservoir, illuminating a low water light or other signal at display 103, and/or activating an alarm. In one exemplary embodiment, the maximum threshold is about 2.2V.
Where a fill operation is undertaken, a low-amplitude or substantially linear voltage signal similar to signal 200 is produced, except the signal has an upward-sloping line to indicate that the level of fluid F is rising as water is added to reservoir 26. In an exemplary fill operation, for example controller 106 may open water valve 38 to raise the level of fluid F—and therefore, the nominal voltage of signal 200- to a designated or pre-determined nominal value. This obviates the need for predetermined valve-open times associated with known controllers, thereby resulting in a highly accurate fill procedure even despite variation in inlet water pressure and the associated rate of incoming water through valve 38. Thus, for example, the use of level sensor assembly 40 with computing system 100 prevents an overfill shutdown condition which might otherwise result when a time-delay fill operation is undertaken with high water pressure at water valve 38.
The steady and low-amplitude signal variation shown in voltage signal 200 of
Where a boiling condition is detected by computing system 100, controller 106 may issue a “boiling” signal to display 103 and/or initiate a timer for timed cooking operations, such that the timer may compare the elapsed boiling time to a user-set or otherwise predetermined cooking time. When the elapsed boiling time reaches the predetermined cooking time, controller 106 may deactivate heaters 24 and issue a “cook time complete” or similar signal.
In some operations of steam cooker 10, steam may be vented from cooking chamber 20 (
Turning now to
Turning now to
In addition to the normal operational states detailed above, computing system 100 and controller 106 may be programmed to detect and react to operational states indicative or improper operation or the need for operator intervention. As detailed below, these states may include fouling or otherwise dirty conditions in the vicinity of level sensor 40, leaking water from reservoir 26, a malfunctioning or leaking water valve 38, and other conditions.
Turning to
Similarly,
In addition, reduced float amplitude during boiling may indicate float assembly 42 is starting to bind or stick on probe 46. If the amplitude of signal 240 is with respect to average level 242 is reduced by a threshold amount from a designated normal amplitude while temperature sensor 110 indicates a temperature of at least 210 F, computing system 100 may determine a “float sticking” operational fault with the same corrective actions as noted above. In an exemplary embodiment, a reduction of amplitude of at least 20% from a normal boiling amplitude (as discussed above) may meet the threshold for a “float sticking” operational fault.
Alternatively, computing system 100 may be programmed to determine that float assembly 42 is completely stuck in some operational states. For example, when water valve 38 is activated by controller 106, if computing system 100 does not detect an increase in voltage output by sensor 48 for at least a predetermined time (e.g., between 3 and 5 seconds), then computing system 100 may determine that either float assembly 42 is stuck in position on probe 46, or that water is not in fact flowing into reservoir 26. In this case, controller 106 may output a corrective message of “stuck float or water off” or similar, and/or set an alarm or take other corrective action. If temperature sensor 110 detects a temperature within cooking chamber 20 of at least 210 F for a duration of at least 3 minutes, but the voltage level and voltage amplitude remain unchanged over this time interval, then computing system may determine that float assembly 42 is stuck in place on probe 46. For purposes of the present disclosure, the amplitude may be considered “unchanged” if the amplitude does not reach a minimum threshold of +/−0.05 V with reference to the average voltage signal. Controller 106 may then output a corrective message of” stuck float, clean float” or similar, and/or set an alarm or take other corrective action. Similarly, if temperature sensor 110 detects a temperature within cooking chamber 20 of at least 210 F and the voltage is within an operating range between 2.2 V and 3.6 V, but an over-temperature fault occurs indicative of heaters 24 running in a dry reservoir 26, then computing system may determine that float assembly 42 is stuck in place on probe 46 and controller 106 may output a corrective message of” stuck float, clean float” or similar, and/or set an alarm or take other corrective action.
Computing system 100 may also monitor the nominal voltage received from sensor 48 over time and make determinations about the state of sensor 48 and/or the larger computing system 100. For example, if the voltage output from sensor 48 is between 0.0 V and 0.2 VDC for at least 10 seconds, then computing system 100 may determine that no power is being provided to sensor 48. Controller 106 may then output a fault message of” level sensor —no power” or similar to display 103, and/or set an alarm or take other corrective action. If the voltage output from sensor 48 is between 4.8 V and 5.2 V for at least 10 seconds then computing system 100 may determine that sensor 48 has been shorted. Controller 106 may then output a fault message of” level sensor—shorted power” or similar to display 103, and/or set an alarm or take other corrective action. If the voltage output from sensor 48 is about 2.6 V for at least 10 seconds with minimal variation (e.g., within 0.2 V), then computing system 100 may determine that magnet 44 is absent from the vicinity of sensor 48, because some natural voltage variation is expected from sensor 48 when float assembly 42 is mounted on probe 46 as shown in operational signal 200 of
Computing system 100 may also be programmed to operate controller 106 in a “marine mode,” in which a special set of operating parameters is designed to account for the natural rocking motion encountered by a steam cooker 10 positioned on a ship at sea. Detection of the presence of steam cooker 10 aboard a ship at sea is accomplished by computing system 100 observing a wave-shaped signal 270, shown in
In addition, an overfill operational state (described above with respect to maximum threshold 204 of signal 200) will not activate until signal 200 continuously exceeds threshold 204 for a threshold time, such as between 8 and 12 second, such as 10 seconds.
Further, for a water fill operation in marine mode, controller 106 opens water valve 38 for a “fill” period of 4 seconds followed by a 10 second delay. If the desired level of fluid F has not been achieved after the delay, another 4 second fill and 10 second delay is initiated. This process repeats until the desired level of fluid F is maintained for the entire 10 second delay period.
If the amplitude of signal 270 falls to 0.4 V or less throughout a 15 second time window, then marine mode may be disabled by computing system 100. This results in a resumption of regular operating parameters, including the ceasing of signal averaging, resuming normal fill operations, and turning off the marine mode signal on display 103.
Thus, as described in detail above, computing system 100 can receive the analog voltage output from the Hall effect sensor 48 and determine a level of fluid F contained in reservoir 26 from the corresponding axial position of the Hall effect sensor 48 along its range of axial travel along probe 46. Software 108 can further interpret such analog level signals for expanded capability and diagnostics, including predictive diagnostics that can predict a failure before it occurs. In particular, the waveform and timing of the analog level signal can be interpreted by controller 106 and software 108 to provide automatic capabilities.
While this invention has been described as having exemplary designs, the present invention may be further modified with the spirit and scope of this disclosure. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.
This application is a continuation of U.S. patent application Ser. No. 15/982,770, filed May 17, 2018, the entire disclosures of which is hereby expressly incorporated herein by reference.
Number | Name | Date | Kind |
---|---|---|---|
2736822 | Dunlap, Jr. | Feb 1956 | A |
2987669 | Kallmann | Jun 1961 | A |
3114478 | Hilkemeier et al. | Dec 1963 | A |
3437771 | Nusbaum | Apr 1969 | A |
3467135 | Muskalla | Sep 1969 | A |
4056979 | Bongort et al. | Nov 1977 | A |
4253149 | Cunningham et al. | Feb 1981 | A |
4459584 | Clarkson | Jul 1984 | A |
4507976 | Banko | Apr 1985 | A |
4589282 | Dumery | May 1986 | A |
4646796 | Krause | Mar 1987 | A |
4730491 | Lew | Mar 1988 | A |
4804944 | Golladay et al. | Feb 1989 | A |
4810965 | Fujiwara et al. | Mar 1989 | A |
4852404 | Catanese | Aug 1989 | A |
5159268 | Wu | Oct 1992 | A |
5294917 | Wilkins | Mar 1994 | A |
5339699 | Carignan | Aug 1994 | A |
5410913 | Blackburn | May 1995 | A |
5421193 | Carlin | Jun 1995 | A |
5426271 | Clark et al. | Jun 1995 | A |
5444369 | Luetzow | Aug 1995 | A |
5497081 | Wolf et al. | Mar 1996 | A |
5636548 | Dunn et al. | Jun 1997 | A |
5686894 | Vig et al. | Nov 1997 | A |
6058926 | Ruiz | May 2000 | A |
6124709 | Allwine | Sep 2000 | A |
6218949 | Issachar | Apr 2001 | B1 |
6253611 | Varga et al. | Jul 2001 | B1 |
6418788 | Articolo | Jul 2002 | B2 |
6430380 | Kawakami | Aug 2002 | B2 |
6453802 | Manganiello et al. | Sep 2002 | B1 |
6510397 | Choe | Jan 2003 | B1 |
6612404 | Sweet et al. | Sep 2003 | B2 |
6670806 | Wendt | Dec 2003 | B2 |
6690159 | Burreson et al. | Feb 2004 | B2 |
6810732 | Shon | Nov 2004 | B2 |
6813946 | Benton | Nov 2004 | B1 |
6923057 | Sabatino | Aug 2005 | B2 |
6992478 | Etherington et al. | Jan 2006 | B2 |
7222530 | Fukuhara et al. | May 2007 | B2 |
7343800 | Harman | Mar 2008 | B2 |
7377162 | Lazaris | May 2008 | B2 |
7398682 | Magers et al. | Jul 2008 | B2 |
7530269 | Newman et al. | May 2009 | B2 |
7581434 | Discenzo et al. | Sep 2009 | B1 |
7725273 | Jannotta | May 2010 | B2 |
7856875 | Jeon | Dec 2010 | B2 |
8421448 | Tran et al. | Apr 2013 | B1 |
9046407 | Young et al. | Jun 2015 | B2 |
9151657 | Ross et al. | Oct 2015 | B2 |
9297686 | Ross, Jr. | Mar 2016 | B1 |
9335201 | Huang et al. | May 2016 | B2 |
9389295 | Kurniawan | Jul 2016 | B2 |
9404454 | Achor | Aug 2016 | B2 |
9423288 | Zanetti et al. | Aug 2016 | B2 |
9423894 | Olsson | Aug 2016 | B2 |
9464929 | Farmanyan | Oct 2016 | B2 |
9525309 | Cummings | Dec 2016 | B2 |
10209120 | Boecker | Feb 2019 | B2 |
20050109105 | Kowalski et al. | May 2005 | A1 |
20050120793 | Cochran et al. | Jun 2005 | A1 |
20120318252 | Seitz et al. | Dec 2012 | A1 |
20140130874 | Burlage et al. | May 2014 | A1 |
20170074715 | Bartos et al. | Mar 2017 | A1 |
Number | Date | Country |
---|---|---|
2012284251 | Mar 2014 | AU |
204493043 | Jul 2015 | CN |
07-260552 | Oct 1995 | JP |
2002-174544 | Jun 2002 | JP |
2006055006 | May 2006 | WO |
2008120222 | Oct 2008 | WO |
2011101642 | Aug 2011 | WO |
2017087896 | May 2017 | WO |
Entry |
---|
AccuTemp Owners Manual for Evolution Steamer, dated Oct. 30, 2009. 21 Pages. |
Guide to Selecting the Ideal Pneumatic Cylinder Positioning Application, dated Feb. 26, 2018. 7 pages. |
Sensor Choices for Pneumatic Cylinder Positioning, dated Jun. 30, 2016. 15 pages. |
Number | Date | Country | |
---|---|---|---|
20210348962 A1 | Nov 2021 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 15982770 | May 2018 | US |
Child | 17208270 | US |