Patent Description:
This application is related to patent application serial no. <CIT>, which corresponds to <CIT>, claiming benefit to provisional patent application serial nos. <CIT> and serial no.

The aforementioned applications were all assigned to the assignee of the present application, which builds on this family of technology.

This invention relates to a technique for sensing the volume and/or viscosity of concrete in a rotating container or drum.

The assignee of the present invention has developed a means of measuring entrained air in wet concrete, which is disclosed in the aforementioned patent application serial no. The measurement device or acoustic probe is called, or known in the industry as, AIRtrac™ or AIRtrac Mobile™. The AIRtrac™ sensor may be permanently installed on a rotating container / concrete mixer drum or on the hatch door of a concrete mixer drum.

Consistent with that disclosed in the aforementioned patent application serial no. <CIT>(<NUM>-<NUM>-<NUM>-<NUM>), and by way of example, <FIG> show the AIRtrac™ sensor, that is generally indicated as <NUM> and may include an acoustic-based air probe like element <NUM>. The acoustic-based air probe <NUM> may include an acoustic source generally indicated as <NUM> (see <FIG>) configured to provide an acoustic signal into a mixture of concrete; and an acoustic receiver generally indicated as <NUM> (see <FIG>) configured to be substantially co-planar with the acoustic source <NUM>, to respond to the acoustic signal, and to provide signaling containing information about the acoustic signal injected into the mixture of concrete. By way of example, the acoustic source <NUM> may consist of an arrangement of parts and components and is best shown in detail in <FIG>. By way of example, the acoustic receiver <NUM> may consist of at least an arrangement of one or more transducers and fills and is best shown in <FIG>.

The acoustic-based air probe <NUM> may include a planar probing surface <NUM> having a first aperture 106a formed therein configured to receive part of the acoustic source <NUM>, including a hardened steel piston <NUM>, as best shown in <FIG>. At the interface with the planar probing surface <NUM>, the hardened steel piston <NUM> is surrounded by a circumferential channel 122a, so as not to be in physical contact with the planar probing surface <NUM>. The planar probing surface <NUM> may include at least one second aperture 106b, 106c formed therein configured to receive at least one part <NUM>', <NUM>" of the acoustic receiver <NUM>. The part <NUM>', <NUM>" are shown as a protective polyurethane rubber member in <FIG>. The planar probing surface <NUM> may be configured as a hardened steel face plate, although the scope of the invention is intended to include using other type or kinds of materials either now known or later developed in the future. The acoustic receivers <NUM> are configured in relation to the center of the hardened steel piston <NUM> of the acoustic source <NUM> and defined by a radius R, as best shown in <FIG>, so that the acoustic receivers <NUM> are arranged and configured substantially on the circumference of a circle defined by the radius R from the center of the hardened steel piston <NUM>.

The acoustic receiver <NUM> may include, or take the form of, a dynamic pressure transducer, as best shown in <FIG>.

In operation, and by way of example, the acoustic receiver <NUM> may be configured to receive acoustic signals, e.g., having a frequency in a range of about <NUM>-<NUM>, including <NUM>, although the scope of the invention is intended to include using other frequencies and other ranges either now known or later developed in the future.

By way of example, the acoustic source <NUM> may include, or take the form of, or be configured as, a floating mass, consistent with that shown in <FIG>.

In <FIG>, the acoustic source <NUM> is shown in the form of a piston module assembly <NUM> having the rigid hardened steel piston <NUM> configured with a channel <NUM> to receive, or be coupled to, a piston shaft <NUM>. The acoustic-based air probe <NUM> has a base plate disk <NUM> that contains the piston module assembly <NUM>, as well as other components in <FIG>. The rigid hardened steel piston <NUM> is enclosed, surrounded and configured to move in relation to a low durometer cast silicone rubber <NUM> and photo-etched flexures <NUM>, so as to provide the floating mass aspect of the acoustic source <NUM>. The low durometer cast silcone rubber <NUM> may also be configured to perform sealing functionality in relation to the mixture of the concrete. The acoustic source <NUM> may also include a vibration isolated actuator block assembly <NUM>, best identified in <FIG>, having a stationary voice coil actuator field assembly <NUM> in combination with a voice coil actuator field assembly <NUM> having an accelerometer transducer configuration. The vibration isolated actuator block assembly <NUM> may be configured to drive and vibrate the piston shaft <NUM>, consistent with that shown in <FIG>, so as to provide the acoustic signal to the mixture of the concrete when the acoustic-based air probe is inserted into the mixture. The apparatus <NUM> may also be configured with signal processing technology (not shown) for driving the acoustic source <NUM>, as would be appreciated by a person skilled in the art.

The acoustic-based air probe <NUM> may include a fluid/media temperature sensor <NUM>, consistent with that shown in <FIG>, configured to provide a temperature reading of the mixture.

The acoustic-based air probe <NUM> may include a voice coil temperature sensor <NUM>, consistent with that shown in <FIG>, configured to provide a temperature reading of the stationary voice coil actuator field assembly <NUM>.

The acoustic-based air probe <NUM> may include two acoustic receivers <NUM>, <NUM>', that may take the form of the two dynamic pressure transducers, consistent with that shown in <FIG>.

The acoustic-based air probe <NUM> may include some combination of a connector/wiring cover plate <NUM>, and various connectors configured in relation to the same, including a pressure sensor no. <NUM> connector <NUM> for providing the signaling in relation to one pressure sensor, a pressure sensor no. <NUM> connector <NUM> for providing the signaling in relation to the other pressure sensor, a voice coil drive connector <NUM> for providing the signaling in relation to the voice coil drive <NUM> (<FIG>), a temperature sensor connector <NUM> for providing the signaling in relation to a temperature, and an accelerometer connector <NUM> for providing the signaling in relation to the voice coil actuator moving coil assembly <NUM> (<FIG>), all shown in <FIG>.

<CIT> discloses a system for monitoring the mixing of a slurry in a rotating drum by mounting a blade having a strain-gauge that measures forces acting thereon by the slurry rotating in the drum, as well as a contact angle, an angular speed, and a blanking angle, and determines information about of a volume of concrete based upon the same.

<CIT> discloses a technique for measuring concrete using a sensor having a hollow body with strain gauges attached thereto that is arranged in relation to fins or blades. It measures and uses forces Fp and Fv to determine information about the slump of the concrete. It discloses also a system for sensing the volume, or the viscosity, or both, of concrete in a rotating container or drum according to the preamble of claim <NUM>.

<CIT> discloses a probe and method for obtaining rheological property value.

The present invention relates to a system according to the appended claims. Particularly, it provides a new use of air measurement information provided by the AIRtrac™ sensor, e.g., including quality of signal and other diagnostics to discern when the probe is submerged in concrete and when it's not. That air measurement information coupled with sensor location information provided by the AIRtrac™ sensor, estimated slump, drum speed, drum size and dimensions can all be used to give an accurate estimate of how much concrete is currently in the container/mixer drum. This will particularly useful when part of a load is discharged and a specific amount of concrete (what should be left in the drum) is required for another job.

By way of example, the AIRtrac™ sensor may be mounted on hatch door or side wall of mixer drum. Its power source can be inductive, solar or battery.

In operation, the AIRtrac™ sensor will report air content in the wet concrete. Once the concrete is covering the AIRtrac™ sensor, the AIRtrac™ will also begin to report real-time air by volume information.

In its broadest sense, the present invention provides a new and unique system for sensing the volume and/or viscosity of a slurry (including concrete) contained in a rotating container or drum, having a sensor and a signal processor.

The sensor is configured to attach inside a rotating container or drum having a known geometry, sense angular positions of the sensor and also sense associated entry and exit points when the sensor enters and exits the slurry, including concrete, contained in the rotating container or drum, and provide signaling containing information about the angular positions and the associated entry and exit points.

The signal processor is configured to receive the signaling, and determine corresponding signaling containing information about a volumetric amount, or a viscosity, or both, of the slurry in the rotating container or drum, based upon the signaling received.

The system may also include one or more of the following features:
The sensor may include a <NUM>-axis accelerometer configured to respond to the angular positions of the sensor at given times, and provide angular position signaling containing information about the angular positions of the sensor at the given times.

The signal processor may be configured to determine the volumetric amount based upon static pressure readings contained in the signaling received that increase when the sensor enters the concrete and decrease when the sensor exits the concrete.

The sensor may include a pressure transducer configured to sense static pressure when the sensor enters and exits concrete contained in the rotating container or drum and provide static pressure signaling containing information about the static pressure sensed.

The signal processor may be configured to determine the associated entry and exits points of the sensor using a least squares curve fitting algorithm.

The signal processor may be configured to determine the volumetric amount based upon acoustic energy readings contained in the signaling received that increases when the sensor enters the concrete and decreases when the sensor exits the concrete.

The sensor may include a piston arranged in the rotating container or drum and configured to generate pulses; and a pressure transducer arranged in the rotating container or drum at a known distance from the piston and configured to sense the pulses generated and provide acoustic energy signaling containing information about the pulses sensed, including where the magnitude of acoustic energy sensed by the pressure transducer is low when the pulses are generated and sensed in air, and where the magnitude of acoustic energy sensed by the pressure transducer is high when the pulses are generated and sensed in the concrete.

The signal processor may be configured to determine the viscosity based upon the amount of "tilt" of the concrete in the rotating container or drum and the speed of rotation of the rotating container or drum.

The signal processor may be configured to determine the amount of "tilt" of the concrete in the rotating container or drum based upon the angular positions and the associated entry and exit points when the sensor enters and exits concrete contained in the rotating container or drum.

The signal processor may be configured to determine the rotation speed of the rotating container or drum based upon the angular positions of the sensor contained in the signaling received.

The signaling may contain information about constituents of the concrete, including the amount of water, sand, rock and respective densities, and the signal processor may be configured to determine the slump of the concrete, based upon the signaling received.

The sensor may be mounted on a hatch door of the rotating container or drum, as well as other parts of the rotating container or drum.

The signal processor is configured to receive signaling containing information about angular positions of a sensor attach inside a rotating container or drum having a known geometry, as well as associated entry and exit points when the sensor enters and exits a slurry (e.g., like concrete) contained in the rotating container or drum, and determine corresponding signaling containing information about a volumetric amount, or a viscosity, or both, of the slurry in the rotating container or drum, based upon the signaling received.

The drawing includes <FIG>, which are not necessarily drawn to scale, as follows:.

The AIRtrac™ mobile sensor measures air content by actively creating acoustic waves and measuring the speed of the waves in the concrete media. This is accomplished by using a piston to "pulse" the concrete and measuring the amount of time it takes for the pulse to travel through the concrete and be detected by a pressure transducer that is known distance away from the piston, e.g., consistent with that set forth above. This works very well for the determination of the air content of the concrete mixture but these components can also be used to measure other aspects of the concrete. The present invention discloses two additional measurements that can be made.

One parameter that is often not known is the precise volumetric amount of concrete that is in a concrete truck, particularly after a partial pour has occurred. Some measurement techniques known in the art look at the hydraulic loading of the drum, however this is often inaccurate as it requires knowledge of the exact density of the concrete as well as the knowledge of other parameters such as the air content. Using the AIRtrac™ system a much more direct measurement can be made. This measurement technique utilizes the fact that the AIRtrac™ sensor is submerged under the concrete for part of the drums rotation and then is out of the concrete for the remainder. In addition, the AIRtrac™ device has a <NUM>-axis accelerometer that is used to determine the angular position of the sensor at any given time. The combination of knowing the concrete entry and exit angles along with the geometry of the drum, the volume of the concrete can be calculated. <FIG> shows a diagram of how this can be achieved.

<FIG> shows an approximately half full drum. The AIRtrac™ sensor will enter the concrete at about +<NUM> degrees from vertical and exit at about -<NUM> degrees. This will give an indication that the concrete is occupying about ½ the drum and the volume can be calculated. A simple calculation can be made for other concrete entry/exit angles to yield volume.

The angle of the sensor is always available so the remaining aspect of the measurement is determination of the concrete entry and exit points. Two ways this can be accomplished utilize the pressure transducer. First, a static pressure can indicate when the sensor is under concrete. While in air above the concrete the pressure transducer will show close to <NUM> pressure, but as the senor enters the concrete the weight of the concrete will cause a pressure reading. This reading will increase until the sensor is at the bottom of the drum and then decrease until the sensor emerges from the concrete on the other side. Various analysis techniques including least squares curve fitting can be used to extrapolate the exact entry and exit points of the pressure sensor. A second detection technique can utilize the magnitude of the acoustic signal the pressure sensor sees as it is generated by the piston. Air is highly attenuative to acoustic waves so when the AIRtrac™ is in air the pressure transducer will see very little of the acoustic energy generated by the piston, while once the sensor is in the concrete the signal level will rise dramatically. This can also be used to determine when the AIRtrac™ sensor enters and leaves the concrete within the drum.

A second parameter of the concrete that the AIRtrac™ can determine is the viscosity of the concrete. The viscosity of a fluid is directly related to the ability of the fluid to flow. Therefore, in a rotating container or drum like a concrete truck a low viscosity fluid will remain very level while a very viscous fluid will tend to not flow very well and will ride up the wall of the drum as the drum exits the fluid. <FIG> shows diagrams of the effect.

The amount of the "tilt" of the concrete in the drum will depend on the viscosity of the fluid (or concrete) and the speed of rotation of the drum. The drum rotation speed can be determined by the <NUM>-axis accelerometer and the "tilt" can be determined by the same techniques described above. With knowledge of these parameters along with geometric shape of the drum the concrete viscosity can be determined. Furthermore, with knowledge of the concrete constituents including amount of water, sand, rock and their respective densities, the slump of the concrete can be determined.

<FIG> shows a system <NUM> having an acoustic-based sensor <NUM> and a signal processor or signal processing module <NUM> for implementing the present invention.

In operation, the sensor <NUM> is configured to attach inside a rotating container or drum like that shown in <FIG> having a known geometry, sense angular positions of the sensor as the drum rotates, and also sense associated entry and exit points when the sensor enters and exits a slurry (e.g., like concrete) contained in the rotating container or drum, and provide signaling containing information about the angular positions and the associated entry and exit points.

The signal processor <NUM> is configured to receive the signaling sensed, and determine corresponding signaling containing information about a volumetric amount, or a viscosity, or both, of the slurry (like concrete) concrete in the rotating container or drum, based upon the signaling received.

The functionality of the signal processor or processor control module <NUM> may be implemented using hardware, software, firmware, or a combination thereof. In a typical software implementation, the processor module may include one or more microprocessor-based architectures having a microprocessor, a random access memory (RAM), a read only memory (ROM), input/output devices and control, data and address buses connecting the same, e.g., consistent with that shown in <FIG>, e.g., see element <NUM>. By way of example, the input/output devices may be configured to receive the signaling Sin sensed by the sensor <NUM>, and provide the signaling Sin to the signal processor <NUM> for further processing. By way of further example, the input/output devices may be configured to receive the corresponding signaling Sout from the signal processor <NUM>, and provide the corresponding signaling Sout.

A person skilled in the art would be able to program such a microprocessor-based architecture(s) to perform and implement such signal processing functionality described herein without undue experimentation. The scope of the invention is not intended to be limited to any particular implementation using any such microprocessor-based architecture.

By way of example, the present invention is disclosed based upon using the assignee's AIRtrac™ sensor. However, the scope of the invention is not intended to be limited to the same. For example, embodiments are envisioned, and the scope of the invention is intended to include, e.g. using other types or kinds of acoustic-based sensors that may be configured to attach inside a rotating container or drum having a known geometry, sense angular positions of the sensor and sense associated entry and exit points when the sensor enters and exits concrete contained in the rotating container or drum, and provide signaling containing information about the angular positions and the associated entry and exit points.

By way of example, the present invention is disclosed based upon using a rotating drum forming part of a concrete mixing truck. However, the scope of the invention is not intended to be limited to the same. For example, embodiments are envisioned, and the scope of the invention is intended to include, e.g. using other types or kinds of rotating containers or drums that may be configured to receive and contain concrete, as well as rotate and mix the concrete.

By way of example, the present invention is disclosed based upon mixing a slurry like concrete using a rotating drum. However, the scope of the invention is not intended to be limited to the same. For example, embodiments are envisioned, and the scope of the invention is intended to include, e.g. processing other types or kinds of slurries, including other types or kinds of slurries that are sensitive to the amount of entrained air contained therein, other types or kinds of or slurries that are mixed and poured from a rotating container or drum.

Means for attaching a sensor inside a rotating container or drum is known in the art, and the scope of the invention is not intended to be limited to any particular types or kinds thereof,.

By way of example, the sensor may include a sensor housing that may be fastened inside the rotating container or drum using fasteners like screws.

Claim 1:
A system for sensing the volume, or the viscosity, or both, of concrete in a rotating container or drum, comprising:
a sensor (<NUM>) configured to attach inside a rotating container or drum having a known geometry, sense angular positions of the sensor (<NUM>) and sense associated entry and exit points when the sensor (<NUM>) enters and exits a slurry, including concrete, contained in the rotating container or drum, and provide signaling containing information about the angular positions and the associated entry and exit points; and
a signal processor (<NUM>) configured to
receive the signaling, and
determine corresponding signaling containing information about a volumetric amount, or a viscosity, or both, of the slurry in the rotating container or drum, based upon the signaling received, characterized in that the sensor is an acoustic based sensor.