Patent Description:
Insulation materials such as fiberglass batts, rolls, blankets, or blown-in insulation are typically used to reduce the rate of heat transfer between two areas separated by a boundary. For example, in an attic, insulation material can be applied to the interior surface of the roof deck to slow the transfer of heat through the roof deck, that is, from the exterior of the house to the attic or vice versa. In another application, insulation material is applied to exterior walls (e.g., between wood studs) and covered with wallboards to slow the rate of heat transfer through the exterior wall and the wallboard.

In some instances, it is useful to determine the density (e.g., degree of fill) of insulation material within a cavity. For example, in a retrofit application, a technician might determine the density of insulation within an existing cavity to determine what changes, if any, need to be made to make the insulation conform to a density required by an updated building code. In another example, the technician uses a blower to blow loose insulation material into a cavity. In this case, the technician might keep track of the quantity (e.g., weight or volume) of the insulation blown into the cavity and compare that to the volume of the cavity to determine the density of the blown-in insulation. This technique relies on the assumption that the insulation blown into the cavity has a uniform density, which might not be the case. <CIT> relates to various apparatuses and methods for use in determining the density of insulation in a building cavity.

Another known method for determining a density of insulation within a cavity involves inferring the density from the amount a sound wave of known initial intensity is attenuated or dampened as the sound wave travels a known distance through the insulation. Unfortunately, this method has disadvantages. Acoustic contamination (noise) that is often present at construction sites due to drilling, hammering, stapling, sawing etc. can interfere with this method. For example, if the acoustic noise includes the same or nearly the same acoustic frequencies as the test sound wave, it might be difficult or impossible to distinguish the acoustic noise from the attenuated test sound wave.

There are other ways of measuring the density of loose insulation, including the method of the Cubic Foot Density Test (Blow-In-Blanket © Contractors Association - <NUM>) and the Densi-Checker™ offered by Johns Manville for their Jet Spray insulation. However, these methods are destructive in nature, requiring that the area of test be repaired after sampling. It also is less practical to test multiple locations, because of the time involved and the multiple repairs that are required. Off-site testing may be performed as described in "Standard Practice for Determination of Thermal Resistance of Loose-Fill Building Insulation in Side Wall Applications by ASTM Task Group for Sidewall R-value Loose Fill (ATS-<NUM>). " This technique suffers from the time required for testing, and that the results from the sample may not necessarily be representative of the product as installed in the field.

Accordingly, what are needed are improved methods and devices for determining the density of insulation in a cavity.

Described herein is a device for determining the density of insulation (e.g., in a cavity), the device comprising:.

The present invention relates to a method for determining the density of insulation as defined in claim <NUM>.

Additional aspects will be evident from the disclosure herein.

The accompanying drawings are included to provide a further understanding of the methods and devices of the disclosure, and are incorporated in and constitute a part of this specification. The drawings are not necessarily to scale, and sizes of various elements may be distorted for clarity. The drawings illustrate one or more embodiment(s) of the disclosure, and together with the description serve to explain the principles and operation of the disclosure.

As noted above, the present inventors have noted disadvantages of existing processes for determining the density of insulation. Accordingly, a device is described for determining the density of insulation (e.g., in a cavity). The device includes a probe configured to be inserted into insulation such that the probe contacts the insulation. The device further includes an actuator configured to cause the probe to oscillate and a sensor configured to sense the oscillation of the probe. The device further includes a control system configured to cause the actuator to oscillate the probe. The sensor is configured to generate a signal that represents the density of insulation.

In certain embodiments, the probe takes the form of a metal retractable or non-retractable needle that can be inserted through wallboard or other barriers (e.g., through a pre-pierced hole) to be surrounded by the insulation for which the density is to be determined. The actuator may be, for example, a mechanical actuator or an electromagnetic actuator, e.g., in the form of an electromagnet, multiple electromagnets, a hammer, or multiple hammers that can be excited to cause the probe to oscillate within the insulation. The sensor may, for example, take the form of a coil of wire that is magnetically coupled to at least a portion of the oscillating probe. The control system can be implemented with any combination of software and/or hardware as described herein.

As such, the sensor is configured to generate a signal that represents the displacement and/or velocity of the probe, e.g., relative to a resting state as the probe oscillates. By analyzing the signal to determine how the insulation interacts with the oscillating probe (e.g., how the insulation resists or lessens the oscillation of the probe), and by using known characteristics of the insulation, the control system (or a user) can determine the density of the insulation within the cavity.

For example, the signal generated by the sensor may be used to determine a decay constant representing a degree to which the insulation resists the movement of the probe. The determined decay constant can be used to determine the density of insulation. For instance, the determined decay constant can be compared (e.g., via a subtraction or a division operation) to a decay constant representing the degree to which ambient air and/or characteristics of the device resist oscillation of the probe. Additionally, the device may store data indicating correlations between various determined decay constants and respective densities of insulation. The correlations between decay constant and insulation density will vary based on the type of insulation that is under test. Methods disclosed herein involving the determination of decay constants of insulation are compatible with using an oscillatory driving force to oscillate the probe, and are also compatible with imparting an impulse force to the probe. That is, decay constants can be derived from transitory or steady state probe oscillation signals.

In another embodiment, the signal generated by the sensor may be used to determine a decay time during which a displacement amplitude of the oscillating probe is attenuated by the insulation by a predetermined amount (e.g., in the range of <NUM>% to <NUM>%, <NUM>% to <NUM>%, or <NUM>% to <NUM>%, such as, for example, <NUM>%, <NUM>%, <NUM>% or <NUM>%). The determined decay time can be used to determine the density of insulation. For instance, the determined decay time can be compared (e.g., via a subtraction or a division operation) to a decay time during which the displacement amplitude of the probe attenuates by the predetermined amount when oscillating in ambient air (e.g., not surrounded by insulation). Additionally, the device may store data indicating correlations between various determined decay times and respective densities of insulation. The correlations between decay times and insulation density will vary based on the type of insulation that is under test. Methods disclosed herein involving the determination of decay times for insulation are generally compatible with imparting an impulse force to the probe to oscillate the probe and with using an oscillatory driving force to oscillate the probe. However, an oscillatory driving force applied to the probe must discontinue at some point so that the probe oscillation amplitude has a chance to decay so that a decay time can be determined. That is, decay times can generally only be derived from transient probe oscillation signals.

In yet another embodiment, the device rectifies the signal generated by the sensor and integrates the rectified signal over a predetermined duration after onset of free oscillation of the probe to determine an amount of oscillation energy absorbed by the insulation during the predetermined duration. The amount of oscillation energy absorbed by the insulation is then compared (e.g., via a subtraction or division operation) to an amount of oscillation energy that is absorbed in a reference substance (e.g., any gas, liquid, solid, ambient air, or insulation material) during the predetermined duration when the probe freely oscillates in air. This comparison can yield the density of insulation. Alternatively, the device may store data that correlates various amounts of absorbed energy with respective densities, and this data may be used to determine the density of insulation.

In various embodiments, the signal generated by the sensor is provided for output via an output device such as a display screen, an oscilloscope, a voltmeter, and/or an analog-to-digital converter (A/D converter). For example, the display screen or oscilloscope may display the signal in the form of voltage over time. The voltmeter may display an RMS voltage value that corresponds to the signal. The A/D converter might be used to convert the signal to a digital format that is displayable by a display screen, for example. In other examples, a display screen might display the density of insulation (e.g., g/cm<NUM>) automatically determined by the control system.

In certain embodiments, the device may include an input device, such as a touchscreen, a keyboard etc. In such embodiments, the control system can be configured to receive input from the input device representing known characteristics of the insulation (e.g., the composition of the insulation). The control system may use this information in conjunction with analysis of the signal generated by the probe to determine the density of the insulation within the cavity.

Also described herein is another device for determining the density of insulation (e. g, within a cavity). The device includes a probe configured to be inserted into insulation such that the probe contacts the insulation, a base component to which the probe is mechanically coupled, and a sensor configured to generate a signal representing displacement and/or velocity of the probe within the insulation. In this context, the displacement and/or velocity of the probe indicates the density of insulation.

The device may include a control system (e.g., hardware and/or software) configured to cause displacement of the probe and/or configured to use the generated signal to determine the density of insulation. In this context, using the signal may include digitizing the signal and processing the signal.

The probe may include a non-magnetic material. The probe could be coupled to the base component at a first end of the probe such that a second opposing end of the probe is configured to be inserted into the insulation. Or, the probe could be coupled to the base component at a location between first and second opposing ends of the probe. As such, the probe might include a counterweight located at the first end of the probe, such that the second end of the probe is configured to be inserted into the insulation.

The device may include a protrusion (e.g., retractable or non-retractable needle) that extends from the base component, the protrusion being configured to be inserted into the insulation. Similarly, the probe itself might include one or more retractable or non-retractable needles for insertion into the insulation.

The sensor may include a coil of wire that defines a gap. Accordingly, the probe might include a magnetic component (e.g., a permanent magnet) that is configured to move with respect to the gap and the probe could be magnetically coupled to the coil of wire. In this context, the sensor can be configured to generate the signal via sensing movement of the magnetic component with respect to the gap.

The device may include an actuator configured to displace the probe. For example, the actuator might include an electromagnet, with the control system being configured to provide an excitation current to the electromagnet to displace the probe. In other embodiments, the actuator might include a hammer, with the control system being configured to cause the hammer to strike the probe to displace the probe.

The probe may be coupled to the base component via a spring. Additionally, a mechanical latch might be configured to restrict movement of the probe. Additionally, the device might include a magnetic component attached to the base component that is configured to repel the probe away from the sensor or attract it towards the sensor.

The control system may be configured to use the generated signal to determine the density of insulation (e.g., based on known characteristics of the insulation). In this context, using the signal may include digitizing the signal and processing the signal. For example, the device can include an input device, with the control system being configured to: receive input, from the input device, representing the known characteristics of the insulation, and use the received input to determine the density of insulation.

The device may include an output device, with the control system being configured to cause the output device to provide output characterizing the determined density of insulation and/or the generated signal.

The output device may include an oscilloscope, a voltmeter, an analog-to-digital converter, and/or a display screen.

The signal may represent displacement and/or velocity of the probe relative to the sensor with respect to time.

According to an embodiment, a method for determining the density of insulation (e.g., within a cavity) is described, for example, using any of the aforementioned devices. The method includes placing a probe into contact with the insulation (e.g., fibrous insulation material), displacing the probe in a first direction such that potential energy is stored, releasing the probe such that the probe (a) moves in a second direction to reach a point of maximum displacement in the second direction, the second direction being opposite the first direction, and/or (b) moves back in the first direction after reaching the point of maximum displacement, and generating, via a sensor, a signal that indicates the point of maximum displacement.

In preferred embodiments, displacing the probe in the first direction can include displacing the probe in the first direction prior to placing the probe into contact with the insulation.

In particular embodiments, the probe includes a non-magnetic material and/or one or more retractable or non-retractable needles.

In some embodiments, the sensor includes a coil of wire that defines a gap. In this context, the probe might include a magnetic component (e.g., a permanent magnet) that is configured to move with respect to the gap and is magnetically coupled to the coil of wire. As such, generating the signal might include generating the signal via movement of the magnetic component with respect to the gap.

In particular embodiments, placing the probe into contact with the insulation includes placing the probe such that at least an end of the probe is surrounded by the insulation.

In some embodiments, displacing the probe in the first direction includes displacing the probe with an electromagnet. In this context, releasing the probe might include shutting off the electromagnet, decreasing the power provided to the electromagnet, or reversing the polarity of the electromagnet by reversing the direction of current flow through the coil of the electromagnet.

In other embodiments, displacing the probe in the first direction includes manually displacing the probe. The potential energy can be stored by holding the probe with a mechanical latch. In some embodiments, the probe moves in the second direction at least in part due to a magnetic component of the device repelling the probe.

In particular embodiments, the method also includes inserting a protrusion (e.g., a retractable or non-retractable needle) into the insulation (at any angle) to stabilize the device, with the protrusion being coupled to the probe via a base component.

In some embodiments, the method includes using the generated signal to determine the density of insulation (e.g., based on known characteristics of the insulation). For example, the method might include receiving input, from an input device, representing the known characteristics of the insulation, and using the received input to determine the density of insulation.

In particular embodiments, the method includes providing, via an output device, output characterizing the determined density of insulation and/or the generated signal. The output device can include an oscilloscope, a voltmeter, an analog-to-digital converter, and/or a display screen.

In some embodiments, the signal represents displacement and/or velocity of the probe relative to the sensor with respect to time.

Any of the devices described herein can be stabilized against a floor with an external stand (e.g., tripod) to minimize movement of the device while in use. Additionally or alternatively, any of the devices described herein can include additional structural members that can be used to stabilize or brace the device against the frame of a cavity (e.g., wall studs) to minimize movement of the device while in use.

Referring now to the drawings, <FIG> is a schematic view of a device <NUM> for determining the density of insulation <NUM> (e.g., fibrous insulation material) in a cavity <NUM>, according to one embodiment of the disclosure. The cavity <NUM> may take the form of a space between wood studs of a wall. In this case, the insulation <NUM> may be exposed or may be concealed behind a wallboard. In another example, the cavity <NUM> is concealed behind a sheet (e.g., of netting, paper, or fabric) that is attached to a roof deck, thereby defining the cavity <NUM>. Other examples are possible.

The device <NUM> includes a probe <NUM> configured to be inserted (e.g., via protrusion 110a) into the cavity <NUM> containing the insulation <NUM> such that the probe <NUM> contacts and/or is surrounded by the insulation <NUM>. (See <FIG>. ) The device <NUM> also includes an actuator <NUM> configured to cause the probe <NUM> to oscillate, and a sensor <NUM> configured to sense the oscillation of the probe <NUM>. The device <NUM> further includes a control system <NUM> configured to cause the actuator <NUM> to oscillate the probe <NUM>. The sensor <NUM> is configured to generate a signal <NUM> that represents the density of the insulation <NUM> in the cavity <NUM>. In another sense, the signal <NUM> represents a displacement and/or a velocity of the probe <NUM> relative to the sensor <NUM>. In some embodiments, the sensor <NUM> and the actuator <NUM> could be implemented as a single electromagnetic device.

The probe <NUM> may take the form of a metal or plastic bar that is coupled to a base component <NUM> at an end <NUM> of the probe <NUM>. The probe <NUM> is configured to oscillate at an opposite end <NUM>. The end <NUM> of the probe <NUM> may include a protrusion 110a. In some examples, the protrusion 110a includes one or more retractable or non-retractable needles. The probe <NUM> may include at least a portion that includes a magnetic material and/or a magnetic component <NUM> (e.g., a permanent magnet) that is attached to the probe <NUM> proximate to the sensor <NUM>. The probe <NUM> may also include another magnetic (e.g., ferromagnetic) component <NUM> proximate to the actuator component <NUM>.

The device <NUM> can also include non-magnetic (e.g., plastic) stops <NUM> and <NUM> placed between the top and bottom portions of the actuator <NUM>. The plastic stops <NUM> and <NUM> can help prevent the probe <NUM> from making contact with the actuator <NUM>. The plastic stops <NUM> and <NUM> can be placed anywhere on the device <NUM> to help prevent the probe <NUM> from making contact with the actuator <NUM>.

In one example, the actuator takes the form of one or more electromagnets, e.g., a coil of wire that surrounds a magnetic core. As shown in <FIG>, the actuator <NUM> includes electromagnets (e.g., horseshoe magnets) on opposing sides of the probe <NUM>. In this example, the control system <NUM> includes a power supply configured to provide excitation current(s) <NUM> to the actuator <NUM> to cause oscillation of the probe <NUM>. In this example, the probe <NUM> includes a magnetic portion <NUM> so that a magnetic field generated by the actuator <NUM> can impart a locomotive force to the probe <NUM>. In another example, an actuator takes the form of a hammer that the control system <NUM> may operate to strike the probe and cause oscillation of the probe. The actuator may take the form of any mechanical or electromagnetic apparatus that is configured to cause the actuator to oscillate the probe.

The sensor <NUM> takes the form of a coil of wire that defines a gap <NUM>. In this example, the control system <NUM> is configured to receive the signal <NUM> generated by the sensor <NUM> sensing movement of the magnetic component <NUM> through the gap <NUM>.

The control system <NUM> may be implemented via any combination of hardware and/or software to implement the functionality described herein. For example, the control system <NUM> may include one or more processors (e.g., general purpose processors, digital signal processors, special purpose processors) and a memory (e.g., volatile, nonvolatile, removable, non-removable, magnetic, optical, or flash storage) storing instructions that, when executed by the one or more processors, cause the device <NUM> to perform any of the functions described herein. In another example, the control system <NUM>, may include special purpose hardware that is hard-wired to perform the functions described herein. Other examples are possible. Additionally, the control system <NUM> may include a discrete low pass filter as described further herein.

The user interface <NUM> enables interaction between a user (if applicable) and the device <NUM>. As such, the user interface <NUM> may include input devices such as a keyboard, a keypad, a mouse, a touch-sensitive panel, a microphone, push buttons, and/or a camera. The user interface <NUM> may also include output devices such as a display screen (which, for example, may be combined with a touch-sensitive panel), an audio speaker, a haptic feedback system, a voltmeter, an analog-to-digital converter, and/or an oscilloscope. The user interface <NUM> is connected to the control system <NUM> via connection <NUM>, which may be a wired or wireless connection.

The device <NUM> may include an additional base component <NUM> that is coupled to the base component <NUM>, the actuator <NUM>, and the sensor <NUM>, as shown in <FIG> and <FIG>. The base component <NUM> may include a retractable or non-retractable protrusion <NUM> that extends from the base component <NUM>. As shown in <FIG>, the protrusion <NUM> (e.g., a retractable or non-retractable needle) may be used to establish a positional reference point in the insulation <NUM> for the actuator <NUM> and sensor <NUM> and to stabilize the device <NUM> during operation via inserting the protrusion <NUM> through the barrier (if present) and into the insulation <NUM>.

The device <NUM> may include yet another base component <NUM> that is coupled to the base component <NUM> and the actuator <NUM>, as shown in <FIG> and <FIG>. The base component <NUM> may include a protrusion <NUM> that extends from the base component <NUM>. As shown in <FIG>, the protrusion <NUM> (e.g., a retractable or non-retractable needle) may be used to establish a second positional reference point in the insulation <NUM> for the actuator <NUM> and sensor <NUM> and to stabilize the device <NUM> during operation via inserting the protrusion <NUM> through the barrier (if present) and into the insulation <NUM>.

In some embodiments, one or more of the protrusion <NUM>, the end <NUM>, or the protrusion <NUM> are accompanied with respective (e.g., plastic) caps or sleeves that cover their sharp tips when not in use to protect users and/or the tips.

In some embodiments, the protrusions <NUM> and <NUM> may be part of a larger set of protrusions that encircle the probe <NUM>.

<FIG> is a block diagram of a method <NUM> for determining the density of insulation in a cavity according to one embodiment of the disclosure.

At block <NUM>, the method <NUM> includes placing a probe into contact with the insulation in the cavity. For example, as illustrated in <FIG>, the probe <NUM> is placed into contact with the insulation <NUM> within the cavity <NUM>. The probe <NUM> can be inserted into the insulation at any angle with respect to a wall, an insulation cavity, or a floor. This may involve the protrusion 110a being inserted through a pierced hole in a barrier (e.g., a fabric) in front of the insulation <NUM> or may simply involve inserting the probe <NUM> directly into the exposed insulation <NUM>. In some embodiments, the probe <NUM> includes a sharp cutting surface that can be used to cut a hole in a (e.g., paper or fabric) barrier that encloses a cavity such that the hole in the barrier allows freedom of movement for the probe <NUM>. In preferred embodiments, the end <NUM> of the probe <NUM> is placed into contact with the insulation <NUM> such that the end <NUM> of the probe <NUM> is surrounded by the insulation <NUM>. The protrusion <NUM> may be inserted into the insulation <NUM> and/or through the barrier as well to stabilize the device <NUM> or establish a positional reference for the probe <NUM> during operation.

At block <NUM>, the method <NUM> includes causing, via an actuator, the probe to oscillate while in contact with the insulation. Depending on the form of the actuator, the control system <NUM> may cause the actuator to oscillate the probe in a number of ways. For example, the actuator <NUM> may take the form of one or more electromagnets, and the control system <NUM> provides an excitation current <NUM> to the actuator <NUM> to oscillate the probe <NUM>. In another example, the actuator may take the form of one or more hammers, and the control system <NUM> may, via an arm or similar means, mechanically force the hammer(s) to strike the probe <NUM>, causing the probe <NUM> to oscillate.

As such, excitation of the probe <NUM> via the actuator <NUM> may take different forms. For instance, the actuator <NUM> may impart an oscillatory (e.g., sinusoidal) driving force to the probe <NUM> in response to receiving an oscillatory (e.g., sinusoidal) excitation current <NUM> from the control system <NUM>. In some examples, the probe <NUM> is oscillated in this way until the oscillation of the probe <NUM> reaches a substantially steady state amplitude within the insulation <NUM>. In other examples, the excitation current <NUM> may be an impulse current that causes the actuator <NUM> to impart a transitory impulse force to the probe <NUM>.

In some embodiments, the actuator includes a first electromagnet that is positioned on a first side of the probe and a second electromagnet that is positioned on a second opposing side of the probe. In this context, causing the probe to oscillate via the actuator while in contact with the insulation may include alternatingly: repelling or attracting, via the first electromagnet, the probe toward the second electromagnet, and repelling or attracting, via the second electromagnet, the probe toward the first electromagnet.

In certain embodiments, the probe includes a magnetic component positioned between the first electromagnet and the second electromagnet. In this context, repelling or attracting the probe via the first electromagnet toward the second electromagnet may include repelling or attracting the magnetic component and repelling or attracting the probe via the second electromagnet toward the first electromagnet may include repelling or attracting the magnetic component.

In additional embodiments, repelling or attracting the probe via the first electromagnet toward the second electromagnet may include exciting the first electromagnet with a DC-pulsed current, and repelling or attracting the probe via the second electromagnet toward the first electromagnet may include exciting the second electromagnet with a DC-pulsed current.

Referring to <FIG> for example, the first electromagnet of the actuator <NUM> that is below the probe <NUM> may repel the probe <NUM> away (e.g., up) from the first electromagnet toward the second electromagnet that is above the probe <NUM>. While the probe <NUM> is reaching (or after the probe <NUM> has reached) an oscillatory position near the second electromagnet, the second electromagnet may begin repelling the probe <NUM> away (e.g., down) from the second electromagnet toward the first electromagnet. More specifically, the first and second electromagnets may primarily repel the magnetic protrusion <NUM> and thus the probe <NUM> as a whole.

Alternatively, the first electromagnet of the actuator <NUM> that is below the probe <NUM> may attract the probe <NUM> toward the first electromagnet. While the probe <NUM> is reaching (or after the probe <NUM> has reached) an oscillatory position near the first electromagnet, the second electromagnet may begin attracting the probe <NUM> toward the second electromagnet.

The first and second electromagnets may receive respective first and second DC-pulsed currents that are out of phase, or sinusoidal waveforms that are out of phase to exert a push-pull force on the probe, or may receive half-wave rectified sinusoidal waveforms that are out of phase to exert a push-only or pull-only force on the probe to perform these functions.

At block <NUM>, the method <NUM> includes generating, via a sensor, a signal that represents the density of insulation in the cavity. For example, the sensor <NUM> senses the oscillation of the probe <NUM> and, in response, generates the signal <NUM>. More specifically, the movement of the magnetic component <NUM> through the gap <NUM> causes the signal <NUM> to be generated. Accordingly, the signal <NUM> represents displacement and/or velocity of the probe <NUM> relative to the sensor <NUM> with respect to time.

The control system <NUM> (or a user) may use the signal <NUM> in conjunction with known characteristics (e.g., composition) of the insulation <NUM> to determine the density of insulation <NUM> in the cavity <NUM>. For example, the user interface <NUM> may receive, via an input device, input representing known characteristics of the insulation <NUM>. As such, the control system <NUM> may use the known characteristics represented by the received input and the signal <NUM> to determine the density of the insulation <NUM> as described further below.

More specifically, the control system <NUM> (or a user) may use the signal <NUM> to determine a decay constant representing a degree to which the insulation <NUM> resists oscillation of the probe <NUM>, and use the determined decay constant to determine the density of insulation <NUM> in the cavity <NUM>. To this end, the determined decay constant may be compared to a (reference) decay constant representing a degree to which ambient air and/or characteristics of the probe <NUM> resist oscillation of the probe <NUM>. In other examples, the determined decay constant may be "looked up" in a data table that maps the determined decay constant to a density of the insulation <NUM> based on the composition of the insulation <NUM>.

Additionally or alternatively, the control system <NUM> (or a user) may use the signal <NUM> to determine a decay time during which a displacement amplitude of the probe <NUM> is attenuated by the insulation <NUM> by a predetermined amount after imparting an impulse force to the probe <NUM> via the actuator <NUM>. The control system <NUM> may then use the determined decay time to determine the density of insulation <NUM> in the cavity <NUM> as described further below.

More specifically, the control system <NUM> may use the determined decay time to determine the density of insulation <NUM> in the cavity <NUM> by comparing the determined decay time to a second decay time during which the displacement amplitude of the probe <NUM> attenuates by the predetermined amount when oscillating in air. To this end, the determined decay time may be compared to the second decay time via subtracting the determined decay time from the second decay time. In other examples, the determined decay time may be "looked up" in a data table that maps the determined decay time to a density of the insulation <NUM> based on the composition of the insulation <NUM>.

Referring to <FIG> for instance, two different signals <NUM> are depicted respectively by the waveform <NUM> and the waveform <NUM>. The waveform <NUM> depicts a signal <NUM> representing oscillation of the probe <NUM> in ambient air, that is, while the probe <NUM> is not inserted into the insulation <NUM>. The waveform <NUM> depicts a signal <NUM> representing oscillation of the probe <NUM> while the probe <NUM> is inserted into insulation <NUM> having an unknown density. Hereinafter, decay time may refer to the time that passes while the signal <NUM> exhibits a <NUM>% decline in amplitude, and decay constant may refer to the reciprocal of that decay time.

As such, the waveform <NUM> shows a signal <NUM> that exhibits an approximate <NUM>% attenuation in amplitude over about <NUM>. Therefore, the decay time for waveform <NUM> is about <NUM> and the decay constant is about <NUM>-<NUM>. The waveform <NUM> shows a signal <NUM> that exhibits an approximate <NUM>% attenuation in amplitude over about <NUM>. Therefore, the decay time for waveform <NUM> is about <NUM> and the decay constant is about <NUM>-<NUM>. The decay time of <NUM> or the decay constant of <NUM>-<NUM> can be "looked up" in an appropriate data table to yield the density for the insulation <NUM>, as represented by the waveform <NUM>.

In various examples, it may be useful to perform various signal processing operations upon the signal <NUM> for more reliable results. For example, in determining the density of the insulation <NUM>, the control system <NUM> may be configured to perform any of the following operations upon the signal <NUM>: a low pass filter operation, digital sampling, discrete data filtering, a square root operation, a sum operation, a multiplicative scaling operation, or a rectification operation.

In a particular embodiment, the control system <NUM> or a discrete low pass filter included therein may be configured to remove high frequency components from the signal <NUM>, such as artifacts that reflect the impact force of the actuator <NUM>. Next, the signal <NUM> may be sampled <NUM>,<NUM> times over a <NUM> second interval, that is, at a <NUM> sampling rate. In other examples, the sampling rate might vary from <NUM>-<NUM>. The signal <NUM> may then be rectified, i.e., any negative displacement values of the signal <NUM> are multiplied by -<NUM>. Additionally, data points of the signal <NUM> whose absolute value is greater than a particular amplitude may be deleted from the signal <NUM> and disregarded. Next, a square root operation may be performed on the signal <NUM> to emphasize purely oscillatory portions of the signal <NUM> as compared to portions of the signal <NUM> that reflect any impulse provided by the actuator <NUM>. Lastly, the displacement, velocity, or voltage values of the signal <NUM> may be summed and/or multiplicatively scaled, which serves as an integration of the signal <NUM> over a predetermined duration. The result of the integration reflects how much energy was sustained as oscillation of the probe <NUM> as opposed to friction generated within the insulation <NUM> over the predetermined duration. The energy that is sustained as oscillation of the probe <NUM> can be compared to a reference amount of energy that represents the amount of energy that is sustained by the probe <NUM> over the predetermined duration when the probe is oscillating in ambient air. Alternatively, the amount of energy determined from the integration can be "looked up" in a data table that maps the determined amount of energy to a density of insulation <NUM>.

Once data is obtained in the form of a determined density of the insulation <NUM> (e.g., g/cm<NUM>), the data can be displayed in numeric form on a display screen of the user interface <NUM>. Alternatively, the signal <NUM> can be provided directly in the form of output to possible output devices of the user interface <NUM> such as an oscilloscope, a voltmeter, or an analog-to-digital converter.

It will be appreciated by one of skill in the art that a variety of devices can receive the output, and that the output could also be transmitted by non-direct means, such as to a smart phone, computer or tablet device by wireless means. Such means could include Bluetooth or WiFi or radio frequency transmission to devices capable of receiving such signals.

The ability of such signals to be analyzed by devices that prospective users might already own (such as a cell phone, smart phone, tablet or computer) could mean that the cost of a measurement device could be considerably less expensive than if the output device was integrated into the measurement device directly. Likewise, providing the display or data analysis in an external device can reduce the weight and size of the measurement device, improving its usability and durability in the field.

In one particular embodiment, the probe <NUM> may be excited with impact forces that are perpendicular to each other. For example, an additional actuator may be configured to apply a force to the probe <NUM> that causes the probe <NUM> to oscillate in the x-y plane, whereas the force applied to the probe <NUM> by the actuator <NUM> may cause the probe <NUM> to oscillate in the x-z plane. Accordingly, an additional sensor may be configured to sense oscillation of the probe <NUM> in the x-y plane, whereas the sensor <NUM> senses oscillation of the probe <NUM> in the x-z plane.

As such, an additional example method includes causing, via the second actuator, the probe <NUM> to oscillate within the x-y plane. The method further includes sensing, via the second sensor, oscillation of the probe <NUM> within the x-y plane, and generating, via the second sensor, a signal that represents displacement and/or velocity of the probe <NUM> within the x-y plane with respect to time.

<FIG> includes a photograph of an experimental device <NUM> similar to the device <NUM> of <FIG> and <FIG> and a photograph of a text fixture <NUM>.

<FIG> depicts experimental data obtained by oscillating the probe of the device of <FIG> within material (cotton) held within the text fixture of <FIG>. As shown in <FIG>, the waveform labeled "undamped ringdown" exhibits a smaller decay constant that that shown by the waveform labeled "tested on cotton.

<FIG> depicts additional experimental data obtained by oscillating the probe of the device of <FIG> within material held within the text fixture of <FIG>. More specifically, <FIG> depicts a first waveform in the upper left corner and a second waveform in the bottom left corner. As shown, increased density of insulation material results in an increased decay constant.

<FIG> depicts additional experimental data obtained by oscillating the probe of the device of <FIG> within material held within a text fixture. The waveform of <FIG> exhibits a very high decay constant which correlates with a high density of insulation material.

<FIG> is a schematic diagram of a device <NUM> for determining the density of the insulation <NUM>. The device <NUM> includes a probe <NUM> configured to be inserted into the insulation <NUM> such that the probe <NUM> (e.g., the protrusion <NUM> of the probe <NUM>) contacts the insulation <NUM>. The device <NUM> further includes a base component <NUM> to which the probe <NUM> is mechanically coupled, and a sensor <NUM> configured to generate a signal <NUM> representing displacement and/or velocity of the probe <NUM> (e.g. displacement and/or velocity of the protrusion <NUM>) within the insulation <NUM>. In this context, the displacement and/or velocity of the probe <NUM> represented by the signal <NUM> indicates the density of the insulation <NUM>.

The device <NUM> also includes a control system <NUM> that is configured to cause displacement (e.g., movement or oscillation) of the probe <NUM> within the insulation <NUM> and/or configured to use the generated signal <NUM> to determine the density of the insulation <NUM> (e.g., based on known characteristics of the insulation <NUM>). In this context, using the signal may include digitizing the signal and processing the signal. The control system can have any of the components, characteristics, or functionality of the control system <NUM> described above.

The probe <NUM> can include (e.g., be composed of) a magnetic material and can be coupled to the base component <NUM> (e.g., via a rotatable shaft) at a location <NUM> between the first end <NUM> and the second opposing end <NUM> of the probe <NUM>. The probe <NUM> further includes a counterweight <NUM> located at the first end <NUM> of the probe <NUM>. The second end <NUM> of the probe <NUM> is configured to be inserted into the insulation <NUM>, as shown. The probe <NUM> includes the protrusion <NUM> (e.g., a retractable or non-retractable needle). The probe <NUM> is coupled to the base component <NUM> via a spring <NUM>. The probe <NUM> can have any of the components, characteristics, or functionality of the probe <NUM> described above.

The base component <NUM> includes a protrusion <NUM> (e.g., a retractable or non-retractable needle) that extends from the base component <NUM>, with the protrusion <NUM> being configured to be inserted into the insulation <NUM>. The protrusion <NUM> might be used to stabilize the device <NUM> and/or establish a positional reference for the device <NUM> during use (e.g., while the end <NUM> is inserted into the insulation <NUM>). The protrusion <NUM> can have any of the components, characteristics, or functionality of the protrusion 110a described above.

The sensor <NUM> includes a coil of wire that defines a gap. The probe <NUM> includes a magnetic component <NUM> (e.g., a permanent magnet) that is configured to move (e.g., along with the displacement of the probe <NUM> within the insulation <NUM>) with respect to the gap and is magnetically coupled to the coil of wire. The sensor <NUM> is configured to generate the signal <NUM> via sensing movement of the magnetic component <NUM> with respect to the gap (e.g., with respect to the sensor <NUM>). The sensor <NUM> can have any of the components, characteristics, or functionality of the sensor <NUM> described above. In some embodiments, the sensor <NUM> and the actuator <NUM> could be implemented as a single electromagnetic device.

The device <NUM> also includes an actuator <NUM> configured to displace the probe <NUM>. The actuator <NUM> can take the form of an electromagnet, with the control system <NUM> being configured to provide an excitation current <NUM> to the electromagnet to displace the probe <NUM>. In other embodiments, the actuator takes the form of a hammer, with the control system <NUM> being configured to cause the hammer to strike the probe <NUM> to displace the probe <NUM>. The actuator <NUM> can have any of the components, characteristics, or functionality of the actuator <NUM> described above.

In some embodiments, the device <NUM> includes a mechanical latch configured to restrict movement of the probe <NUM> (e.g., while the device <NUM> is not in use).

The control system <NUM> is configured to use the generated signal <NUM> to determine the density of the insulation <NUM> (e.g., based on known characteristics of the insulation <NUM>). In this context, using the signal may include digitizing the signal and processing the signal. For example, the device <NUM> can determine the density of the insulation <NUM> by way of the input device <NUM>, which can have any of the components, characteristics, or functionality of the input device <NUM>. The control system <NUM> is configured to: receive input, from the input device <NUM>, representing the known characteristics of the insulation <NUM>, and use the received input to determine the density of the insulation <NUM>.

In various embodiments, the signal <NUM> generated by the sensor <NUM> is provided for output via an output device such as a display screen, an oscilloscope, a voltmeter, and/or an analog-to-digital converter (A/D converter). For example, the display screen or oscilloscope may display the signal in the form of voltage with respect to time or probe displacement and/or velocity with respect to time. The voltmeter may display an RMS voltage value that corresponds to the signal. The A/D converter might be used to convert the signal to a digital format that is displayable by a display screen, for example. In other examples, a display screen might display the density of insulation (e.g., g/cm<NUM>) automatically determined by the control system <NUM>.

The device <NUM> includes an adjustable stop <NUM> that can prevent the probe <NUM> from contacting the actuator <NUM> or the sensor <NUM>.

In any of the devices disclosed herein, one or more sensors can be configured to indicate when the probe makes contact with adjustable stops, so that any related measurement can be ignored.

<FIG> is a schematic diagram of a device <NUM> for determining the density of the insulation <NUM>. The device <NUM> is generally similar to the device <NUM> with a notable difference being how the probe <NUM> is mechanically coupled to the base component <NUM> when compared to the probe <NUM> and the base component <NUM>. For example, the end <NUM> of the probe <NUM> may be embedded within the base component <NUM> or may be coupled to the base component <NUM> via a rod that allows the probe <NUM> to freely pivot. As shown in <FIG>, the probe <NUM> is coupled to the base component <NUM> at a first end <NUM> of the probe <NUM> such that a second opposing end <NUM> of the probe <NUM> is configured to be inserted into and move within the insulation <NUM>.

The device <NUM> also includes a magnetic component <NUM> that is attached to the base component <NUM>. The magnetic component <NUM> (e.g., a permanent magnet) is configured to repel the probe <NUM> by repelling the magnetic component <NUM> (e.g., a permanent magnet of the same polarity) away from the magnetic component <NUM>. For example, when the actuator <NUM> is disabled and no longer attracts the probe <NUM>, the probe <NUM> (e.g., the end <NUM>) might freely move away from the magnetic component <NUM>.

Otherwise, the components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> can have any of the components, characteristics, or functionality of the respective components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

In some embodiments, one or more of the end <NUM>, the protrusion <NUM>, the protrusion <NUM>, or the protrusion <NUM> are accompanied by respective (e.g., plastic) caps or sleeves that cover their sharp tips when not in use to protect users and/or the tips.

<FIG> is a block diagram of a method <NUM> for determining the density of insulation (e.g., within a cavity), for example, using any of the devices <NUM>, <NUM>, or <NUM>.

At block <NUM>, the method <NUM> includes placing a probe into contact with the insulation. In preferred embodiments, the probe is placed into contact with the insulation after block <NUM> is performed, that is, after the probe is displaced in the first direction (see below). As illustrated in <FIG>, the probe <NUM> (e.g., the end <NUM> of the probe <NUM>) can be placed into contact with the insulation <NUM> within the cavity <NUM>. As alternatively illustrated in <FIG>, the probe <NUM> (e.g., the end <NUM> of the probe <NUM>) can be placed into the contact with the insulation <NUM> within the cavity <NUM>. In either case, the end <NUM> or the end <NUM> can be surrounded by the insulation <NUM> after insertion of the probe. Additionally, the protrusion <NUM> or the protrusion <NUM> can be inserted into the insulation <NUM> to stabilize the device during use of the device. Additionally or alternatively, block <NUM> may be performed using any techniques described above as related to block <NUM> of the method <NUM>. In some embodiments, the probe <NUM> and/or the probe <NUM> include respective sharp cutting surfaces that can be used to cut a hole in a (e.g., paper or fabric) barrier that encloses a cavity such that the hole in the barrier allows freedom of movement for the probe.

At block <NUM>, the method <NUM> includes displacing the probe in a first direction such that potential energy is stored. In preferred embodiments, the probe is displaced in the first direction before being placed into contact with the insulation. For example, the probe <NUM> can be displaced in a first direction <NUM> via magnetic attraction of the actuator <NUM> or by hand. That is, the control system <NUM> can provide an excitation current <NUM> to the actuator <NUM> such that the probe <NUM> (e.g., the magnetic component <NUM> of the probe <NUM>) is attracted to the actuator <NUM>. The potential energy can be stored via the spring <NUM>. The magnetic component <NUM> typically includes a ferromagnetic material.

Similarly, the probe <NUM> can be displaced in the first direction <NUM> via magnetic attraction of the actuator <NUM> or by hand. That is, the control system <NUM> can provide an excitation current <NUM> to the actuator <NUM> such that the probe <NUM> (e.g., the ferromagnetic component <NUM> of the probe <NUM>) is attracted to the actuator <NUM>. The potential energy can be stored by a spring-loaded joint at the end <NUM>, by bending of the probe <NUM>, or by other means.

In some embodiments, the potential energy is stored by holding the probe <NUM> or the probe <NUM> in place with a mechanical latch (not shown).

At block <NUM>, the method <NUM> includes releasing the probe such that the probe (a) moves in a second direction to reach a point of maximum displacement in the second direction, the second direction being opposite the first direction, and/or (b) moves back in the first direction after reaching the point of maximum displacement.

For example, the control system <NUM> may discontinue providing the excitation current <NUM> to the actuator <NUM> to release the probe <NUM>. In another example, the probe <NUM> may be manually released. In another example, the probe <NUM> may be restricted from moving by a mechanical latch and is released by a momentary pulse being delivered to actuator <NUM> thus greatly reducing the power consumption of the actuator. In any event, upon release, the probe <NUM> will begin moving in the second direction <NUM> via conversion of potential energy stored by the spring <NUM> or the probe <NUM> into kinetic energy. The end <NUM> of the probe <NUM> will eventually decelerate and reach a point of maximum displacement in the second direction <NUM>. The stiffness of the probe <NUM> or the operation of the actuator <NUM> might then cause the end <NUM> to move back in the first direction <NUM>.

By additional example, the control system <NUM> may discontinue providing the excitation current <NUM> to the actuator <NUM> to release the probe <NUM>. In another example, the probe <NUM> may be manually released or released by decreasing the power provided to the electromagnet, or reversing the polarity of the electromagnet by reversing the direction of current flow through the coil of the electromagnet. In any event, upon release, the probe <NUM> will begin moving in the second direction <NUM> via conversion of potential energy stored by a spring-loaded joint or the probe <NUM> into kinetic energy. Potential energy of the probe <NUM> might also be stored in the form of a repulsive magnetic field between the magnetic component <NUM> and the magnetic component <NUM>. The end <NUM> of the probe <NUM> will eventually decelerate and reach a point of maximum displacement in the second direction <NUM>. The stiffness of the probe <NUM> or the operation of the actuator <NUM> might then cause the end <NUM> to move back in the first direction <NUM>.

At block <NUM>, the method <NUM> includes generating, via a sensor, a signal that indicates the point of maximum displacement. For example, the sensor <NUM> can generate the signal <NUM> that represents the point of maximum displacement of the probe <NUM>. Or, the sensor <NUM> can generate the signal <NUM> that represents the point of maximum displacement of the probe <NUM>. As noted above the signal <NUM> can be generated via movement of the magnetic component <NUM> with respect to the sensor <NUM>. The signal <NUM> can be generated via movement of the magnetic component <NUM> (e.g., a permanent magnet) with respect to the sensor <NUM>.

In various examples, the control system <NUM> can use the signal <NUM> to determine the density of the insulation <NUM> (e.g., based on known characteristics of the insulation <NUM>). Similarly, the control system <NUM> can use the signal <NUM> to determine the density of the insulation <NUM> (e.g., based on known characteristics of the insulation <NUM>).

Additionally, the input device <NUM> may receive input representing the known characteristics of the insulation <NUM>, and the control system <NUM> can use the received input to determine the density of insulation <NUM>. The input device <NUM> and the control system <NUM> can operate similarly as well.

In various examples, an output device can provide output characterizing the generated signal. Additionally or alternatively, block <NUM> may be performed using any techniques described above as related to block <NUM> of the method <NUM>.

Claim 1:
A method for determining the density of insulation (<NUM>) in a wall cavity (<NUM>), the method comprising:
placing a probe (<NUM>) into contact with the insulation (<NUM>) such that at least an end (<NUM>) of the probe (<NUM>) is surrounded by the insulation (<NUM>);
causing, via a first actuator (<NUM>), the probe (<NUM>) to oscillate within a first plane while in contact with the insulation (<NUM>);
sensing via a first sensor (<NUM>), oscillation of the probe (<NUM>) within the first plane;
causing via a second actuator, the probe to oscillate within a second plane that is perpendicular to the first plane;
sensing via a second sensor, oscillation of the probe (<NUM>) within the second plane; generating, via the first sensor (<NUM>), a signal (<NUM>) that represents the displacement and/or velocity of the probe (<NUM>) within the second plane with respect to time; and using the generated signal (<NUM>) to determine the density of insulation (<NUM>).