Internal measurement feedback auger system

An auger system having an auger with an internal measurement system that is contained within the auger. The measurement system has a power source located within the auger and a sensor for measuring at least one condition within the auger. The measurement system is connected to the power source and a transmitter is powered by the power source to transmit a signal from the sensor. A receiver receives the signal from the transmitter and is spaced from the transmitter. The signal is then sent to a control system that compares the signal to a predetermined value to determine whether the condition measured is within an acceptable range. The control system may alter inputs into components for moving the auger until said condition is within an acceptable range.

BACKGROUND OF THE INVENTION

Auger systems are commonly used to move granular materials that are stored in piles. Such augers can be used to move piles of material located within various storage vessels (such as buildings, tanks, silos, or domes) or they can be used to move material stored in open piles that are not inside any storage building. The augers typically include a hollow shaft surrounded by flights that convey material in an axial direction along the auger as it is rotated about its central axis. In addition to rotating about its axis, an auger is advanced laterally into a pile of material that rests upon the auger. There are two basic types of unloading auger systems that are defined by how their lateral movement through the pile of material takes place:

1) augers that rotate in a circular fashion through a pile and convey the stored material to a center point and into a secondary conveyor outside of the pile.

2) augers that move linearly through a pile to convey the stored material to a secondary conveyor outside of the pile.

The loads that the auger and its mechanical drive system experience are dependent upon numerous factors, including but not limited to the height and size of the storage vessel, the depth of the stored material, the characteristics of the stored material, the temperature and humidity of the storage environment, the design of the auger system, the speed of auger rotation and the rate of auger advancement into the stored material. The loads placed on an auger and its drive system lead to stress within them.

As the auger advances into the pile, the auger can bow or deflect as a result of forces that act laterally on the auger. Furthermore, some materials cause the auger to want to climb onto the pile, providing another source for deflection of the auger. The forces from rotating a deflected auger can cause metal fatigue and bearing wear, both of which can result in failure of the auger system. Applying a lateral force to advance an auger into a pile causes cyclical forces as the auger rotates about its axis. Cyclical forces can exacerbate metal fatigue that eventually results in fractures or breakage of the auger tube. Bearing wear can eventually result in excessive bearing temperature leading to bearing failure and subsequent auger failure.

Either bearing failure or auger failure can also occur as a result of excessive torque or thrust loads in response to the auger advancing into the material pile and conveying material from that pile. Auger vibration is another factor which can lead to premature auger failure.

To operate an auger system in an optimally efficient manner, the auger rotational speed and the auger advancement rate into the material pile should be controlled to keep auger parameters such as deflection, torque, thrust, vibration and temperature limited to within an acceptable range. Each of these parameters can cause stress on the auger that may cause it to fail prematurely.

Traditionally, estimating auger parameters to keep them within acceptable levels has been limited to indirect measurements. Loads placed on an auger can be estimated indirectly by monitoring the current drawn through the electrically-powered auger-drive systems or through monitoring the hydraulic pressure on hydraulically-powered auger-drive systems. The auger rotation and advancement can be controlled through feedback from these indirect auger load measurements. However, these traditional methods of control are only marginally effective as they do not directly measure the actual auger deflection or auger stress. Additionally, indirectly measuring the aforementioned parameters can only provide an inaccurate estimate of stress and deflection, and even that is only possible when the construction of the auger is considered.

Prior to the method described here, direct measurement of auger parameters on an operating auger system has not been accomplished. Since the auger is rotating and also at least partially covered with material as it moves into and conveys material from the pile, taking real-time direct measurements of auger conditions has been problematic because of three factors: 1) the measurements would need to be taken from inside the rotating auger, 2) sufficient power would need to be supplied to the measurement apparatus located inside the rotating auger, and 3) the measurement results would need to be transmitted to a controller located outside the rotating auger. Taking measurements from inside the auger is difficult because the auger is typically made of metal which is conductive and therefore limits wireless transmission of data. Furthermore, since the typical auger rotation rate is between 10 and 200 rpm the use of electrical unions to transmit power and data is inherently problematic, especially since auger systems are commonly located in hazardous or explosive environments and any traditional revolving contact carries the risk of generating sparks.

The present invention solves these problems, making possible real-time direct measurements of auger parameters inside a rotating auger system. Measurable parameters include, but are not limited to, deflection, stress, torque load, thrust load, vibration and temperature. The measurements of these auger parameters are then transmitted to an auger control system which uses the measurements as feedback to alter the movement of the auger in order to maintain the auger parameters within a desired range and/or to notify the operator of auger conditions.

SUMMARY OF THE INVENTION

The present invention is an auger system having an auger with a shaft that has an outer diameter and an inner diameter. The auger has an inner chamber defined by the inner diameter. The outer diameter includes features for conveying material adjacent to the auger. The auger system has a measurement system that is contained within the inner chamber of the auger. The measurement system has a power source located within the auger. A sensor for measuring at least one condition within the auger is connected to the power source and a transmitter is powered by the power source to transmit a signal from the sensor. A receiver receives the signal from the transmitter and is spaced from the transmitter. The signal is then sent to a control system that compares the signal to a predetermined value to determine whether the condition measured is within an acceptable range. The control system may alter inputs into components for moving the auger until said condition is within an acceptable range.

DETAILED DESCRIPTION OF INVENTION

The internal measurement auger system10of the present invention may be used in several different types of augers that all have common features. A first type of auger system8is illustrated inFIG. 1and has an auger14has a shaft15with an outer diameter16and an inner diameter17. The inner diameter17defines a chamber18. The auger14rotates about its central axis22. Auger advance motors24advance the auger14by rotating the entire auger14laterally along a floor28of the storage structure30in which the auger14is located. The advance motors24rotate the auger14about a fixed center point within the center of the storage structure30.FIG. 2shows more detail about the auger system10shown inFIG. 1. An auger drive motor38rotates the auger14about its central axis through a gearbox40. The drive motor38may be an electric or hydraulic motor. As shown inFIG. 2, the motor38is a hydraulic motor. The auger14has a proximal end44and a distal end48that is supported by a wheel50. The wheel50supports the auger14above the floor28of the storage structure30but does not support it with respect to lateral loads. Helical flights54encircle the auger14and convey material axially along the auger14as it rotates about its axis22. At a point within chamber18, inside the auger14, there is a measurement system49. The measurement system49has an internal power generator58, an antenna60and sensors66,70,74. The internal power generator58is shown more thoroughly inFIGS. 7-9. The power generator58has a sealed tube78that contains a permanent magnet82that rides within the sealed tube78. The tube78is surrounded by a coil84. As the auger14rotates about its central axis22, the magnet82falls through the coil84as gravity acts on it. As the magnet82falls through the coil84it generates electricity. In this manner, the power generator58is completely decoupled from any part of the auger system10so that there is no mechanical link to any part of the auger system10outside of the auger14itself. The power generator58uses its magnet82as a weight acted upon by gravity to produce power, and it is contemplated that a weight other than the magnet82itself may drive the power generator58to produce the necessary power for the measurement system49to function. The electricity from the power generator58may be passed through power conditioning equipment85such as voltage regulators and/or rechargeable batteries to provide stable and predictable power to the sensors66,70,74and to provide power to a wireless data transmitter88. The sensors are an accelerometer66, a thermocouple70and a strain gauge74. These sensors66,70,74may be placed in appropriate locations along the length of the auger14. Additionally, it may be desirable to place more than one of the sensors66,70,74along the length of the auger14to take data at various points along the auger14. Each of the sensors66,70,74generates a signal that corresponds to values it measures within the chamber18of the auger14. It is contemplated that a replaceable battery may be used in place of the power generator58, however this is less desirable than using a power generator58because a battery would need periodic replacement and may contain chemicals that could potentially leach out into the auger or the stored material. Having the measurement system49completely contained within the chamber18inside the auger14protects it from damage and allows it to function for an extended period of time without maintenance.

An alternate method of internal power generation which uses a focused light source, such as a laser, together with a photovoltaic detector is shownFIGS. 10-11. In this method, power generator58is replaced with a focused light beam71which illuminates photovoltaic detector81. The current generated by detector81is processed in the power management circuit and used to power the sensors66,70&74.

In some instances, it may be desirable to measure overall deflection along a predetermined length of the auger14. A method of directly measuring the deflection along auger14is shown inFIG. 12andFIG. 13A-C. A laser and detector unit73that can produce a laser beam72and detect the reflected laser beam72is located near the gear box40. The laser and detector unit73shines the laser beam72on a concentrically tiered reflector75. The concentrically tiered reflector75includes a first reflective surface76that is aligned with the central axis22of the auger14. A second reflective surface77is located farther from the laser and detector unit73than the first reflective surface76. A third reflective surface79is located farther from the laser and detector unit73than the second reflective surface. When the auger14is in its undeflected state, that corresponds to having no net load placed up on it, the laser beam will strike the first reflective surface76and the detector unit73will be able to determine the measured distance corresponding to the laser beam72striking the first reflective surface76as shown inFIG. 13A. As the auger14deflects, it is bent so that the laser beam72strikes the second reflective surface77(as shown inFIG. 13B) and the detector unit73determines that the auger14has bent enough for the laser beam72to strike the second reflective surface77by calculating the corresponding distance. As the auger14is bent still further, the detector unit73determines the laser beam has struck the third reflective surface79as shown inFIG. 13C. Upon determining the corresponding deflection, the laser and detector unit73is able to send a signal corresponding to the deflection. Each successive reflective surface76,77,79extends radially outward of the nearer reflective surface so that deflection may be calculated based on which reflective surface76,77,79the laser beam strikes.

FIG. 11Bshows a method for measuring auger deflection with photovoltaic detectors. In this case, a focused light beam80, which may be a laser beam, strikes a photovoltaic detector array83, typically consisting of concentric photovoltaic detectors86,87,89that send a signal according to the location where the light beam80strikes each individual photovoltaic detector86,87,89within the photovoltaic detector array83. Larger deflection in the auger14will correspond to the light beam80striking the photovoltaic detector array83more radially outward.

Within the internal measurement system49that includes the power generator58wireless data transmitter88and sensors66,70,74, there are no contacts that can cause sparks because there is no frictional contact having relative movement with respect to another contact as would occur in rotating unions or brushes. The wireless data transmitter88can send data down the length of the auger14by emitting a radio frequency, but may have difficulty sending data through straight through the metal sidewall90of the auger14. It is not necessary that the signal from the wireless data transmitter88be sent through the sidewall90because that data sent down the length of the auger14is detected by a receiver antenna94that may be placed in a location that does not rotate such as the fixed end plate91that shown inFIG. 2. This separation of the receiver antenna94and the wireless data transmitter88provides a physically decoupled connection that is not susceptible to damage from the stored material and will not generate sparks. The transmitter88and receiver antenna94do not make contact. The end plate91acts a receiver base that is fixed from rotation with respect to the auger14. It is contemplated that other locations than the end plate91may act as a receiver base as long as that location for the receiver antenna94allows the receiver antenna94to receive signals within the auger. The location of the receiver antenna94need only provide a means for receiving the signal from the transmitter88.

The data signal from the receiving antenna94must be transmitted out of the auger14and into a feedback control system100. This may be done by using a wireless repeater95that acts as a second transmitter directed to a receiver96as shown inFIG. 6or a rotating electrical union104that is located outside of the storage structure30and away from any potentially explosive dust from the stored material as shown inFIG. 4. This allows the auger14and gearbox40to rotate with respect to the electrical union104as the advance motors24that rotate the auger14laterally about its fixed center within the storage structure30. The rotation rate of this electrical union is extremely slow, since it rotates at the same rate in which the auger cycles around the floor of the storage structure. Typically, this rotation rate is on the order of 1 cycle every 10 hours or more, so there is minimal risk of spark.

The feedback control system100receives signals from the sensors66,70,73,74,81as described above. The control system100may use information from the signals to change inputs to the components that move the auger14such as the auger advance motor(s)24, and auger drive motor38so that the auger14is not subjected to loading that would cause damage to it or the storage structure30. The feedback control system100contains predetermined values that correspond to operating parameters that are acceptable for the auger14to operate under. For instance, the feedback control system100will have predetermined values for acceptable ranges of temperature, acceleration of the auger14, strain within the auger14, and/or deflection of the auger14. The feedback control system100receives signals from the respective sensors66,70,73,81and compares the value that each signal represents to one of the predetermined values it contains with respect to particular operating parameters. If the feedback control system100compares the value corresponding to a particular signal and that signal corresponds to a value condition outside of an acceptable range of operating conditions, the feedback control system100will alter inputs to the auger system10until the auger14is operated in a manner that puts the particular value or values measured by the sensors66,70,73,81within the predetermined values or ranges of values so the auger14is not damaged. The inputs to the auger system10that the feedback control system100can alter include the inputs to the components that drive the auger14such as the auger advance motor24and the drive motor38. Depending on the types of motors24,38used, the feedback control system100may alter electrical or hydraulic power to these motors24,38to achieve the desired conditions within the auger14.

FIGS. 14 and 15illustrate a linear auger180that has a proximal end184that is near auger drive motor188connected to a gearbox194that rotates auger180. The auger advance motor (not shown, located inside carriage204) drives an auger advance shaft198. The auger advance shaft198drives the carriage204and advances the auger180laterally through the pile within the storage structure208. In this case, the proximal end184is on the left hand side as shown inFIG. 14. As such, a distal portion214of the auger180is located at some distance away from the proximal end184and may be deflected as the auger180is advanced through stored material because the distal portion214is not supported to the extent that the proximal end184is supported. As shown inFIG. 14, the internal measurement system49is located at some point inside of the auger180. In the same manner as described above, the data taken from the auger180is processed by a feedback control system100that ensures that the auger180is advanced and rotated at appropriate rates to prevent damage to the auger180. In this case a receiving antenna (not shown) is attached to an endplate fixed to carriage204and mounted so as to protrude inside auger180. The receiving antenna receives a radio signal from the measurement system49located within the auger180in the same manner as show inFIGS. 1-11.

FIGS. 16 and 17illustrate a drum230that conveys cut material232into a mining machine238. The drum230rotates between a transmission244and a bearing plate246. Carbide teeth250extend from the drum230to cut into the material in the path of the drum230and convey the material into the mining machine238. The drum contains the internal measurement system49as described above and transmits data taken to an antenna256fixed with respect to the bearing end plate246. In the mining machine238the auger advance motor (not shown) is contained within the body of the mining machine238and advances the drum230through movement of crawler tracks247. A drive motor249is connected with a belt251to the drum230and through the transmission244rotates the drum230about its axis in the same manner as auger14is rotated. As discussed above, the measurements can be used to change the operation of the drum230or any other component of the mining machine238.

FIGS. 18 and 19illustrate another version of a mining machine280that has a drum284that is supported in its center about a pivotable arm288. The proximal ends290of the drum284are supported by the arm288and distal ends296are cantilevered outwardly from the arm288.FIG. 19shows the internal measurement system49within the drum284. In this case, the drum284includes openings298that allow the signal from the internal measurement system to be transmitted through the drum284and received by a receiving antenna300that is fixed from rotation with respect to the drum284.

In some instances it may be desirable for an auger14to have slip rings320to transmit power and/or signal information through the auger14.FIG. 20shows an auger14with slip rings320near the gearbox322of the auger14. The slip rings320may be used for sending power to sensors324in the auger14and may also be used to transmit signal data from sensors324within the auger14. The slip rings320are located within a dust tight enclosure328. The slip rings320can be used with any of the aforementioned configurations. When slip rings320are used to transmit signal data from sensors to a location outside of the auger14, a transmitter88is not necessary for this purpose.

The invention is not limited to the embodiments described above, but may be modified within the scope of the following claims.