Patent Description:
The subject matter described herein relates to assemblies and methods that monitor movements of pistons, such as air-actuated pistons.

Some actuators include pistons that move up and down along a defined path in response to changes in air pressure. For example, some adhesive dispensing assemblies include air-actuated pistons that rapidly and repeatedly move down and up to direct hot adhesive onto a surface (e.g., of a packaging). These pistons may move down to dispense the adhesive and up to stop dispensing the adhesive. The pistons may move very small amounts during each stroke (e.g., each up-and-down movement) so that the pistons can rapidly move and dispense adhesive to more surfaces than if the pistons moved more slowly.

Completion of the strokes of the pistons may be monitored to ensure that the pistons are moving sufficiently far to dispense the adhesive. The movement of some pistons may be optically monitored by laser light and an optical sensor. But, given that the environment in which this optical monitoring occurs involves the rapid dispensing of an adhesive, the adhesive may block or interfere with the source of the laser light and/or the optical sensor. <CIT> relates to a reciprocating pump with electronically monitored air valve having battery and solenoid electronic monitoring. <CIT> relates to a dosing and apparatus for dosing and applying liquid or pasty media to an object. <CIT> relates to a monitor to check the path of motion of reciprocating piston. <CIT> relates to a power injector having calibrated pressure monitoring functionality.

In one embodiment, a piston monitoring assembly includes a magnetic body coupled to a piston that is configured to move in opposite directions during a piston stroke to dispense a fluid, a magnetic sensor configured to output signals representative of a magnetic field generated by the magnetic body, and a controller configured to examine the signals output by the magnetic sensor and to determine whether the piston is moving far enough to ensure that the fluid is being dispensed during a first movement of the piston in the piston stroke and that the fluid is prevented from being dispensed during a second movement of the piston in the piston stroke.

In one embodiment, a dispensing system includes a dispensing assembly including a piston configured to move in opposite directions during a piston stroke to control dispensing of a fluid adhesive, and a monitoring assembly comprising a magnetic body coupled to the piston and configured to generate a magnetic field. The monitoring assembly also includes a magnetic sensor configured to output a signal representative of the magnetic field generated by the magnetic body. The monitoring assembly also includes a controller configured to examine the signal output by the magnetic sensor and to determine whether the piston is one or more of moving far enough to dispense the adhesive or moving far enough to stop dispensing of the adhesive.

In one embodiment, a method includes obtaining signals from a magnetic sensor that are representative of a magnetic field generated by a magnetic body that is coupled to a piston moving in opposite directions during a piston stroke to dispense a fluid adhesive, and examining the signals output by the magnetic sensor to determine whether the piston is moving far enough to ensure that the fluid adhesive is being dispensed during a first movement of the piston in the piston stroke and that the fluid adhesive is prevented from being dispensed during a second movement of the piston in the piston stroke.

The inventive subject matter may be understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:.

One or more embodiments of the inventive subject matter described herein provide a piston monitoring assembly and method that monitor movements of a piston using a magnetic sensor. The monitoring assemblies and methods can detect small movements of the piston to determine whether complete strokes of the piston are being completed. The monitoring assemblies and methods can be used to determine whether air-actuated pistons are completing strokes of relatively small movements. For example, the monitoring assemblies and methods can verify whether the pistons are completing strokes having a total distance (from the top of the stroke movement to the bottom of the stroke movement) of <NUM> millimeters to <NUM> millimeters.

While the description of one embodiment of the monitoring assemblies and methods relates to monitoring movements of air-actuated pistons used in adhesive applications, not all embodiments of the inventive subject matter are limited in this one. One or more other embodiments may be used to monitor movements of electronically actuated pistons, electromagnetically actuated pistons, pistons that are pneumatically actuated using a fluid other than air, etc. As another example, one or more embodiments may be used to monitor movements of pistons used in applications other than dispensing adhesive, such as pistons that actuate to dispense fluid medications.

<FIG> illustrates one example of a dispensing system <NUM> having a piston monitoring assembly <NUM>. The dispensing system <NUM> includes a dispensing assembly <NUM> and the monitoring assembly <NUM>. The dispensing assembly <NUM> includes a module housing <NUM> having a dispensing end <NUM> by the internal movement of a piston (shown and described below in connection with <FIG>). The dispensing assembly <NUM> can be used to eject an adhesive (e.g., hot glue) from a dispensing opening (shown in <FIG>) in the dispensing end <NUM> of the module housing <NUM>. A valve device <NUM> having one or more valves inside can control the flow of an actuating fluid into and out of the interior of the module housing <NUM>. For example, the valve device <NUM> can control when pressurized air is directed into the module housing <NUM> above the piston (e.g., to move the internal piston down during a stroke of the piston to dispense adhesive) and when the pressurized air is directed into the module housing <NUM> below the piston (e.g., to move the internal piston up during the stroke of the piston to stop dispensing adhesive).

A sensor housing <NUM> of the monitoring assembly <NUM> holds a magnetic sensor (shown in <FIG>) in close proximity to the module housing <NUM>. The sensor housing <NUM> may be coupled to the module housing <NUM>, such as by mechanically securing the sensor housing <NUM> to the module housing <NUM>. The monitoring assembly <NUM> includes a controller (not visible in <FIG> but shown in <FIG>) that is coupled with the magnetic sensor by one or more connections <NUM>. The connection <NUM> shown in <FIG> is a conductive connection formed by one or more wires, cables, buses, or the like. Optionally, the connection <NUM> can include one or more wireless connections.

<FIG> illustrates a cross-sectional view of one embodiment of the dispensing assembly <NUM> and the monitoring assembly <NUM>. <FIG> illustrates a lower portion of the dispensing assembly <NUM>. The module housing <NUM> includes an interior chamber <NUM> in which an elongated shaft <NUM> is located. The shaft <NUM> moves up-and-down along a center axis <NUM> of the shaft <NUM> to control the dispensing of adhesive out of a dispensing opening <NUM> (labeled in <FIG>) in a dispensing body <NUM> of the module housing <NUM>. The dispensing body <NUM> can be a fixture having internal conduits and that is coupled with the rest of the module housing <NUM>.

For example, a flow of adhesive may be provided through a lateral conduit <NUM> (labeled in <FIG>) in a lower portion (e.g., the dispensing body <NUM>) of the monitoring assembly <NUM>. A lower portion of the shaft <NUM> is disposed in a vertical conduit <NUM> (labeled in <FIG>) of the dispensing body <NUM>. The vertical conduit <NUM> intersects the lateral conduit <NUM> in the dispensing body <NUM>. The adhesive can laterally flow or move through the lateral conduit <NUM> and then vertically flow downward in the vertical conduit <NUM> outside of the shaft <NUM>. An outer, lower end <NUM> (labeled in <FIG>) of the shaft <NUM> is larger than the dispensing opening <NUM>. As a result, the bulbous lower end <NUM> of the shaft <NUM> closes the dispensing opening <NUM> such that no adhesive can exit via the dispensing opening <NUM> while the shaft <NUM> is in the position shown in <FIG> (i.e., the top or near the top of the piston stroke). The lower end <NUM> of the shaft <NUM> moves below the dispensing opening <NUM> when the shaft <NUM> moves downward (i.e., toward or at the bottom of the piston stroke). This creates separation between the lower end <NUM> of the shaft <NUM> and the dispensing opening <NUM> in the dispensing body <NUM>. This separation allows adhesive in the vertical conduit <NUM> to exit out of the dispensing opening <NUM> (e.g., onto a target surface).

Movement of the shaft <NUM> is controlled by movement of a piston <NUM> to which the shaft <NUM> is coupled. For example, the piston <NUM> may be coupled to the shaft at or near an opposite end of the shaft <NUM> (opposite to the lower end <NUM> of the shaft <NUM>). The piston <NUM> is located in the interior chamber <NUM> of the module housing <NUM>. The valve device <NUM> can inject or otherwise direct pressurized fluid (e.g., air) into the interior chamber <NUM> via a lower conduit port <NUM> that extends into the interior chamber <NUM> to push the piston <NUM> up in the interior chamber <NUM> to the position shown in <FIG>. The piston <NUM> includes an upper contact surface <NUM> that can contact an interior step <NUM> of the module housing <NUM> to limit how far the piston <NUM> moves up in the interior chamber <NUM> (e.g., in a direction away from the dispensing opening <NUM>). The piston <NUM> can be driven up to the position shown in <FIG> and <FIG> such that the upper contact surface <NUM> contacts the step <NUM>. This pulls the shaft <NUM> up so that the lower end <NUM> of the shaft <NUM> closes the dispensing opening <NUM>.

The valve device <NUM> can then direct pressurized fluid (e.g., air) into the interior chamber <NUM> via an upper conduit port <NUM> (labeled in <FIG>) that also extends into the interior chamber <NUM> to push the piston <NUM> down in the interior chamber <NUM>. The piston <NUM> includes a lower contact surface <NUM> that is opposite of the upper contact surface <NUM> (e.g., the surfaces <NUM>, <NUM> face opposite directions). This lower contact surface <NUM> can contact the lower conduit port <NUM> to limit the downward movement of the piston <NUM>. As described above, this downward movement lowers the shaft <NUM> to separate the lower end <NUM> of the shaft <NUM> from the dispensing opening <NUM> to dispense adhesive.

The movement of the piston <NUM> from the upper position shown in <FIG> and <FIG> to the lower position and back to the upper position is one stroke of the piston <NUM>. The distance between the upper and lower positions of the piston <NUM> may be relatively small, such as <NUM> millimeters to <NUM> millimeters. Alternatively, this can be a longer or shorter distance.

The monitoring assembly <NUM> includes a magnetic sensor <NUM> (shown in <FIG>) disposed in the sensor housing <NUM> and a magnetic body <NUM> (labeled in <FIG>) coupled with the piston <NUM>. The magnetic body <NUM> can be a permanent magnet. Alternatively, the magnetic body <NUM> may be a semi-permanent magnet (e.g., temporary magnet) or electromagnet. The magnetic sensor <NUM> can be an analog magnetic sensor that outputs or generates a voltage (e.g., a direct current) having a magnitude that corresponds with the amount of magnetic field detected by the sensor <NUM>. For example, the magnetic sensor <NUM> can be a Hall effect sensor. A magnetic field inside of the module housing <NUM> prevents voltage from passing through the sensor <NUM>. As the piston <NUM> and the magnetic body <NUM> moves away from the sensor <NUM> during the downward movement of the piston <NUM> during the stroke of the piston, a voltage output of the sensor <NUM> increases. As the piston <NUM> and the magnetic body <NUM> moves toward the sensor <NUM> during the upward movement of the piston <NUM> during the stroke of the piston, the voltage output of the sensor <NUM> decreases. Alternatively, the magnetic sensor <NUM> can be a digital sensor and/or provide an output other than a voltage, such as a digital signal that indicates movement and/or the position of the piston <NUM>. While only one sensor <NUM> and one magnetic body <NUM> are shown, alternatively, more than one sensor <NUM> and/or more than one magnetic body <NUM> may be used.

<FIG> illustrates one example of operation of the monitoring assembly <NUM>. The monitoring assembly <NUM> can include an output device <NUM> that provides notifications of movement of the piston <NUM> in the dispensing assembly <NUM>. A controller <NUM> receives the output from the sensor <NUM> via the connection(s) <NUM>. The controller <NUM> can represent hardware circuitry, such as one or more circuit boards having or coupled with one or more processors (e.g., microprocessors, field programmable gate arrays, microcontrollers, integrated circuits, etc.) that monitors output from the magnetic sensor and controls information presented by the output device <NUM>. The output device <NUM> can represent one or more lights or lamps, an electronic display, a speaker, or the like. The output device <NUM> can be controlled by the controller <NUM> to present notifications of movement of the piston <NUM>. For example, a light may be actuated, a message may be displayed, an alarm may be sounded, etc., responsive to the piston <NUM> not moving through an entire distance of the expected stroke of the piston <NUM>. Stated differently, the controller <NUM> can compare the output by the sensor <NUM> to determine how far the piston <NUM> is moving. If the output indicates that the piston <NUM> is or has moved is less than a designated distance during the downward part of the stroke of the piston <NUM>, then the controller <NUM> can direct the output device <NUM> to provide a notification.

In one embodiment, the hardware circuitry of the controller <NUM> includes an amplifier that can receive a voltage (e.g., twenty-four volts of a positive direct current polarity) when the monitoring assembly <NUM> is activated. The controller <NUM> can be calibrated by way of an input signal or a manual input (e.g., pressing a button of the controller <NUM>) that is provided before movement of the piston <NUM>. For example, the input can be provided to the controller <NUM> while the piston <NUM> is at a known position (e.g., the bottom or lowest position of the stroke). The controller <NUM> can examine the output from the sensor <NUM> when the input is provided for calibration. The controller <NUM> can then associate this output with the zero or lowest position of the piston <NUM>. The controller <NUM> can compare this output to one or more other outputs of the sensor <NUM> to determine where the piston <NUM> is located relative to the known position, when the piston <NUM> is located at the known position, and/or how far the piston <NUM> is from the known position.

Once the dispensing assembly <NUM> is activated, the piston <NUM> moves up and down through the strokes of the piston <NUM>. The movement of the piston <NUM> changes the magnetic field detected by the sensor <NUM> from the magnetic body <NUM>. The strength of the magnetic field perceived by the sensor <NUM> causes the sensor <NUM> to change the voltage that is output to the controller <NUM> by a small amount. The controller <NUM> can measure the output voltage at roughly eight samples per <NUM> microseconds. Alternatively, the controller <NUM> can measure the output voltage more or less frequently.

The controller <NUM> can sort the measurements of the voltage outputs from the sensor <NUM>. For example, the controller <NUM> can use a median sorting algorithm to determine a value of the output of the sensor <NUM> to use to determine the location or movement of the piston <NUM>. The controller <NUM> can apply one or more software filters to analyze the value that is output from the sorting algorithm to determine upper and lower positions of the piston <NUM> during the stroke of the piston <NUM>. For example, the controller <NUM> can identify a maximum value that is output from the sorting and filtering and associate this value with the lowest position of the piston <NUM> during the stroke.

The controller <NUM> can identify a minimum value that is output from the sorting and filtering and associate this value with the highest position of the piston <NUM> during the stroke. The controller <NUM> optionally can adjust one or more of these values or positions due to changes in temperature. The controller <NUM> can examine the distances that the piston <NUM> moves in the stroke over time. If the distances change enough to constitute physical movement of the piston <NUM>, the controller <NUM> can generate and communicate an output signal for the corresponding sensor <NUM> (where multiple sensors <NUM> are used).

For example, if the distances determined by the controller <NUM> are no smaller than a threshold distance, the controller <NUM> can output a signal. If the distances determined by the controller <NUM> are smaller than this threshold distance, then the controller <NUM> may not output a signal. This output signal can be presented by an operator via the output device <NUM>, as described above. Alternatively, if the distances determined by the controller <NUM> are smaller than the threshold distance, the controller <NUM> can output a signal but if the distances determined by the controller <NUM> are no smaller than this threshold distance, then the controller <NUM> may not output the signal. The threshold distance can be a distance that the piston <NUM> needs to move to ensure there is clearance or separation between the lower end <NUM> of the shaft <NUM> and the dispensing opening <NUM> to dispense adhesive.

Alternatively, the controller <NUM> may examine the voltages output by the sensor <NUM> and compare these voltages to a lower threshold voltage and to an upper threshold voltage. The lower threshold voltage may be associated with a position of the piston <NUM> that is high enough to ensure that the lower end <NUM> of the shaft <NUM> closes the dispensing opening <NUM> (which may not be the highest possible position of the piston <NUM>). The upper threshold voltage may be associated with a position of the piston <NUM> that is low enough to ensure that the lower end <NUM> of the shaft <NUM> opens the dispensing opening <NUM> (which may not be the lowest possible position of the piston <NUM>). The controller <NUM> can control the output device <NUM> to notify an operator of the assembly <NUM> responsive to the output from the sensor <NUM> not being as great as the upper threshold voltage (indicating that the piston <NUM> is not low enough to cause the lower end <NUM> of the shaft <NUM> to open the dispensing opening <NUM>).

The controller <NUM> can control the output device <NUM> to notify the operator responsive to the output from the sensor <NUM> not being as small as the lower threshold voltage (indicating that the piston <NUM> is not high enough to cause the lower end <NUM> of the shaft <NUM> to close the dispensing opening <NUM>). Alternatively, the controller <NUM> can control the output device <NUM> to notify an operator of the assembly <NUM> responsive to the output from the sensor <NUM> being at least as large as the upper threshold voltage (indicating that the piston <NUM> is low enough to cause the lower end <NUM> of the shaft <NUM> to open the dispensing opening <NUM>) and the controller <NUM> can control the output device <NUM> to notify the operator responsive to the output from the sensor <NUM> being less than the lower threshold voltage (indicating that the piston <NUM> is high enough to cause the lower end <NUM> of the shaft <NUM> to close the dispensing opening <NUM>).

<FIG> illustrates a flowchart of one example of a method <NUM> for monitoring operation of a dispensing assembly. In one embodiment, the method <NUM> can represent operations performed by the monitoring assembly <NUM> to monitor movement of the piston <NUM> during dispensing of adhesive. At <NUM>, the monitoring assembly is calibrated. For example, the output from the magnetic sensor may be examined while the piston of the dispensing assembly is at a known position (e.g., the bottom position of the stroke of the piston). At <NUM>, signals output by the magnetic sensor are sampled while the dispensing assembly operates. For example, the output from the magnetic sensor is repeatedly examined while the piston moves up and down in the dispensing assembly. At <NUM>, one or more distances that the piston is moving are determined. The distances can be determined by comparing the sensor outputs with each other and/or to the output from the known position of the piston, as described above.

At <NUM>, a determination is made as to whether the distance(s) that the piston is moving is or are large enough to ensure dispensing is occurring. For example, the sensor outputs and/or distances may be compared to one or more thresholds to determine whether the end of the shaft to which the piston is coupled is lowering enough to allow adhesive to be dispensed out of the dispensing opening. The sensor outputs and/or distances may be compared to one or more thresholds to determine whether the end of the shaft to which the piston is coupled is raising enough to prevent adhesive from being dispensed out of the dispensing opening.

If the distance that the piston is moving is long enough to ensure that dispensing is occurring and the dispensing opening is being closed between the dispensing of adhesive, then the dispensing assembly may be operating properly. As a result, flow of the method <NUM> can continue toward <NUM>. At <NUM>, a notification can be provided, such as a light can be activated, a message can be displayed, or the like, to notify the operator that the dispensing assembly is operating properly.

But, if the distance that the piston is moving is not long enough to ensure that dispensing is occurring and the dispensing opening is being closed between the dispensing of adhesive, then the dispensing assembly may not be operating properly. As a result, flow of the method <NUM> can continue toward <NUM>. At <NUM>, one or more responsive actions may be implemented. For example, a notification can be provided, such as a light can be activated, an alarm can sound, a message can be displayed, the dispensing assembly may be deactivated or turned off, or the like, to notify the operator that the dispensing assembly is not operating properly. Alternatively, no responsive action is implemented.

Following <NUM> or <NUM>, the method <NUM> can terminate or flow of the method <NUM> can return to one or more other operations, such as <NUM>.

Optionally, the controller is configured to examine the signals to monitor movement of the piston over distances of no more than <NUM> millimeters.

Optionally, the first movement of the piston is a downward movement of the piston.

Optionally, the second movement of the piston is an upward movement of the piston.

Optionally, the controller is configured to obtain repeated samples of the signals output by the magnetic sensor and to sort the samples to determine an upper position of the piston and a lower position of the piston.

Optionally, the magnetic sensor is configured to output analog voltages as the signals that are output.

Optionally, the magnetic sensor is a first magnetic sensor and further comprising at least a second magnetic sensor configured to output the signals representative of the magnetic field generated by the magnetic body.

Optionally, the controller is configured to examine the signals output by the first magnetic sensor and by at least the second magnetic sensor to determine whether the piston is moving far enough to ensure that the fluid is being dispensed during the first movement of the piston in the piston stroke and that the fluid is prevented from being dispensed during the second movement of the piston in the piston stroke.

Optionally, the controller is configured to examine the signal output by magnetic sensor to ensure that the adhesive is being dispensed during a downward movement of the piston in the piston stroke and that the fluid is prevented from being dispensed during an upward movement of the piston in the piston stroke.

Optionally, the controller is configured to examine the signal to monitor movement of the piston over distances of no more than <NUM> millimeters.

Optionally, the controller is configured to obtain repeated samples of the signal output by the magnetic sensor and to sort the samples to determine an upper position of the piston and a lower position of the piston.

Optionally, the magnetic sensor is configured to output an analog voltage as the signal.

Optionally, the magnetic sensor is a first magnetic sensor and further comprising at least a second magnetic sensor configured to output the signal representative of the magnetic field generated by the magnetic body.

Optionally, the controller is configured to examine the signals output by the first magnetic sensor the at least the second magnetic sensor to determine one or more of whether the piston is moving far enough to ensure that the adhesive is being dispensed.

Optionally, the method also includes sorting the samples to determine an upper position of the piston and a lower position of the piston.

Optionally, the signals are received from the magnetic sensor and at least one additional magnetic sensor.

Optionally, the first movement is upward movement of the piston.

Optionally, the second movement is downward movement of the piston.

"Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description may include instances where the event occurs and instances where it does not. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it may be related. Accordingly, a value modified by a term or terms, such as "about," "substantially," and "approximately," may be not to be limited to the precise value specified. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges may be identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

Claim 1:
A piston monitoring assembly (<NUM>) comprising:
a magnetic body (<NUM>) coupled to a piston (<NUM>) that is configured to move in opposite directions during a piston stroke to dispense a fluid;
a magnetic sensor (<NUM>) configured to output signals representative of a magnetic field generated by the magnetic body (<NUM>); and
a controller (<NUM>) configured to examine the signals output by the magnetic sensor (<NUM>) and to determine whether the piston (<NUM>) is moving far enough to ensure that the fluid is being dispensed during a first movement of the piston (<NUM>) in the piston stroke and that the fluid is prevented from being dispensed during a second movement of the piston in the piston stroke;
wherein the controller (<NUM>) is configured to obtain repeated samples of the signals output by the magnetic sensor (<NUM>) and to sort the samples to determine an upper position of the piston (<NUM>) and a lower position of the piston.