Sensor probe and methods of assembling same

A method of assembling a sensor probe for use in a sensor assembly is provided. The method includes providing an emitter configured to generate at least one forward propagating electromagnetic field from at least one microwave signal and to generate at least one backward propagating electromagnetic field. A data conduit is coupled to the emitter. Moreover, a ground conductor is extended substantially circumferentially about the data conduit. The ground conductor is configured to substantially reduce electromagnetic radiation within the sensor assembly.

BACKGROUND OF THE INVENTION

The embodiments described herein relate generally to power systems and, more particularly, to a sensor probe for use in a sensor assembly and methods of assembling the sensor probe.

At least some known power generation systems include at least one component that may become damaged or worn over time. For example, at least some known power generation systems include machines, such as turbines, that include components such as, bearings, gears, and/or rotor blades that wear over time. Continued operation with a worn component may cause additional damage to other components or may lead to a premature failure of the component or system.

To detect component damage within machines, the operation of at least some known machines is monitored with a monitoring system. At least some known monitoring systems use sensor assemblies that may include proximity sensors and/or sensor probes that use microwave emitters to measure a vibration and/or a relative position of a machine component. More specifically, within at least some known sensor probes, an emitter is used to generate at least one forward propagating electromagnetic field from at least one microwave signal. The machine component may be measured and/or monitored when the machine component interacts with the forward propagating electromagnetic field. More specifically, a loading is induced to the emitter by the interaction between the component and the forward propagating electromagnetic field. Within such systems, the sensor probe is coupled via a data conduit to a signal processing device that generates a proximity measurement based on the loading induced to the emitter.

While such sensor assemblies are generally able to provide fairly accurate proximity measurements, the conduit connecting various components of the sensor assembly may emit small amounts of electromagnetic radiation. For example, the emitter generates at least one backward propagating electromagnetic field. As such, electromagnetic radiation is emitted from the emitter, and thus, the sensor assembly emits electromagnetic radiation as a result of extraneous currents that are channeled through the assembly. When impedance levels vary between the emitter, the data conduit, and the signal processing device, at least one common mode current is generated and channeled between the components. Moreover, the variance in the impedance levels of the components results in an electromagnetic potential that is transmitted to the conduit causing the conduit to radiate electromagnetic waves. Emitting such electromagnetic radiation within the sensor assembly causes the energy within the sensor assembly to be substantially reduced which results in the signal strength generated by the emitter being reduced. The reduced signal strength adversely limits the accuracy of the sensor assembly.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, a method of assembling a sensor probe for use in a sensor assembly is provided. The method includes providing an emitter configured to generate at least one forward propagating electromagnetic field from at least one microwave signal and to generate at least one backward propagating electromagnetic field. A data conduit is coupled to the emitter. Moreover, a ground conductor that extends substantially circumferentially about the data conduit is provided. The ground conductor is configured to substantially reduce electromagnetic radiation within the sensor assembly.

In another embodiment, a sensor probe for use in a sensor assembly is provided. The sensor probe includes an emitter that is configured to generate at least one forward propagating electromagnetic field from at least one microwave signal. The emitter is also configured to generate at least one backward propagating electromagnetic field. The sensor probe includes a data conduit that is coupled to the emitter. Moreover, the sensor probe includes a ground conductor that extends substantially circumferentially about the data conduit. The ground conductor is configured to substantially reduce electromagnetic radiation within the sensor assembly.

In yet another embodiment, a sensor assembly is provided. The sensor assembly includes at least one sensor probe that includes an emitter that is configured to generate at least one forward propagating electromagnetic field from at least one microwave signal. The emitter is also configured to generate at least one backward propagating electromagnetic field. The sensor probe includes a data conduit that is coupled to the emitter. Moreover, the sensor probe includes a ground conductor that extends substantially circumferentially about the data conduit. The ground conductor is configured to substantially reduce electromagnetic radiation within the sensor assembly. Moreover, the sensor assembly includes a signal processing device that is coupled to the sensor probe. The signal processing device is configured to generate a proximity measurement based on the loading induced to the emitter.

DETAILED DESCRIPTION OF THE INVENTION

The exemplary apparatus and methods described herein overcome at least some disadvantages associated with known sensor assemblies used in monitoring systems and/or components. In particular, the embodiments described herein provide a sensor assembly that includes a sensor probe that facilitates substantially reducing electromagnetic radiation within the sensor assembly such that signal strength is maintained. The sensor probe includes a ground conductor that extends substantially circumferentially about a data conduit coupled to an emitter. At least one backward propagating electromagnetic field generated by the emitter is reflected on the ground conductor to interact with a forward propagating electromagnetic field generated by the emitter. This interaction between the forward and backward propagating electromagnetic fields substantially reduces electromagnetic radiation within the sensor assembly. Moreover, the ground conductor also channels extraneous currents, such as common mode currents generated by the emitter and/or the data conduit, to ground, to facilitate reducing electromagnetic radiation within sensor assembly.

FIG. 1shows an exemplary power system100that includes a machine102. In the exemplary embodiment, machine102may be, but is not limited to only being, a wind turbine, a hydroelectric turbine, a gas turbine, or a compressor. Alternatively, machine102may be any other machine used in a power system. In the exemplary embodiment, machine102rotates a drive shaft104coupled to a load106, such as a generator.

In the exemplary embodiment, drive shaft104is at least partially supported by one or more bearings (not shown) housed within machine102and/or within load106. Alternatively or in addition to, the bearings may be housed within a separate support structure108, such as a gearbox, or within any other structure or component that enables power system100to function as described herein.

In the exemplary embodiment, power system100includes at least one sensor assembly110that measures and/or monitors at least one operating condition of machine102, of drive shaft104, of load106, and/or of any other component of power system100. More specifically, in the exemplary embodiment, sensor assembly110is a proximity sensor assembly110that is positioned in close proximity to drive shaft104for use in measuring and/or monitoring a distance (not shown inFIG. 1) defined between drive shaft104and sensor assembly110. Alternatively, sensor assembly110may be any type of sensor assembly for measuring and/or monitoring any other parameter of machine102and that enables system100to function as described herein.

In the exemplary embodiment, sensor assembly110uses microwave signals to measure the proximity of a component of power system100with respect to sensor assembly110. As used herein, the term “microwave” refers to a signal or a component that receives and/or transmits signals having one or more frequencies between about 300 megahertz (MHz) and about 300 gigahertz (GHz). Alternatively, sensor assembly110may measure and/or monitor any other component of power system100, and/or may be any other sensor or transducer assembly that enables power system100to function as described herein. Moreover, in the exemplary embodiment, each sensor assembly110is positioned in any location within power system100. Moreover, in the exemplary embodiment, at least one sensor assembly110is coupled to a diagnostic system112for use in processing and/or analyzing one or more signals generated by sensor assemblies110.

During operation, in the exemplary embodiment, the operation of machine102may cause one or more components of power system100, such as drive shaft104, to change a relative position with respect to at least one sensor assembly110. For example, vibrations may be induced to components and/or the components may expand or contract as an operating temperature within power system100changes. In the exemplary embodiment, sensor assemblies110measure and/or monitor the proximity, such as a static and/or vibration proximity, and/or the relative position of the components relative to each sensor assembly110, and transmit a signal representative of the measured proximity and/or position of the components (hereinafter referred to as a “proximity measurement signal”) to diagnostic system112for processing and/or analysis.

FIG. 2is a schematic diagram of an exemplary sensor assembly110that may be used with power system100(shown inFIG. 1). In the exemplary embodiment, sensor assembly110includes a signal processing device200and a sensor probe202that is coupled to signal processing device200via a data or a signal conduit204. Moreover, in the exemplary embodiment, probe202includes an emitter206that is coupled to and/or positioned within a probe housing208. More specifically, in the exemplary embodiment, probe202is a microwave sensor probe202that includes a microwave emitter206. As such, in the exemplary embodiment, emitter206has at least one resonant frequency that is within a microwave frequency range. More specifically, in the exemplary embodiment, emitter206is operating at a frequency of 3.3 GHz. Alternatively, emitter206may operate at any other frequency level that enables sensor assembly110and system100to function as described herein.

In the exemplary embodiment, signal processing device200includes a directional coupling device210coupled to a transmission power detector212, to a reception power detector214, and to a signal conditioning device216. Moreover, in the exemplary embodiment, signal conditioning device216includes a signal generator218, a subtractor220, and a linearizer222. Emitter206emits at least one forward propagating electromagnetic field224when a microwave signal is transmitted through emitter206. Moreover, in the exemplary embodiment, emitter206emits at least one backward propagating electromagnetic field228. Moreover, backward propagating electromagnetic field228may also be generated when forward propagating electromagnetic field224interacts with an object, such as a drive shaft104or another component of machine102(shown inFIG. 1) and/or of power system100.

During operation, in the exemplary embodiment, signal generator218generates at least one electrical signal with a microwave frequency (hereinafter referred to as a “microwave signal”) that is equal or approximately equal to the resonant frequency of emitter206. Signal generator218transmits the microwave signal to directional coupling device210. Directional coupling device210transmits the microwave signal to transmission power detector212and to emitter206.

As the microwave signal is transmitted through emitter206, forward propagating electromagnetic field224is emitted from emitter206and out of probe housing208. If an object, such as a drive shaft104or another component of machine102(shown inFIG. 1) and/or of power system100enters and/or changes a relative position within forward propagating electromagnetic field224, an electromagnetic coupling may occur between the object and field224. More specifically, because of the presence of the object within electromagnetic field224and/or because of object movement, electromagnetic field224may be disrupted, for example, because of an induction and/or capacitive effect induced within the object, that may cause at least a portion of electromagnetic field224to be inductively and/or capacitively coupled to the object as an electrical current and/or charge. In such an instance, emitter206is detuned (i.e., a resonant frequency of emitter206is reduced and/or changed) and a loading is induced to emitter206. The loading induced to emitter206causes a reflection of the microwave signal (hereinafter referred to as a “detuned loading signal”) to be transmitted through data conduit204to directional coupling device210.

Moreover, backward propagating electromagnetic field228is emitted from emitter206results in electromagnetic radiation (i.e., electromagnetic waves) being emitted from probe and within sensor assembly110. Further, when loading is induced to emitter206, emitter206has an impedance level that varies slightly from both data conduit204and signal processing device200. Moreover, the impendence level of data conduit204varies slightly from the impedance level of signal processing device200. More specifically, in the exemplary embodiment, the impedance level of emitter is approximately 50 Ohms, the impedance level of data conduit204is approximately 47 Ohms, and the impendence level of signal processing device200is approximately 49 Ohms. Alternatively, the impedance levels for emitter206, data conduit204and signal processing device200may be any other level that enables assembly110and system100to function as described herein. As a result of the variation in impedance levels, extraneous currents are generated by emitter206and/or data conduit204. More specifically, in the exemplary embodiment, the extraneous currents generated by emitter206and/or data conduit204include at least one common mode current. Moreover, in the exemplary embodiment, the detuned loading signal has a lower power amplitude and/or a different phase than the power amplitude and/or the phase of the microwave signal. Moreover, in the exemplary embodiment, the power amplitude of the detuned loading signal is dependent upon the proximity of the object to emitter206. Directional coupling device210transmits the detuned loading signal to reception power detector214.

In the exemplary embodiment, reception power detector214determines an amount of power based on, and/or contained within, the detuned loading signal and transmits a signal representative of the detuned loading signal power to signal conditioning device216. Moreover, transmission power detector212determines an amount of power based on, and/or contained within, the microwave signal and transmits a signal representative of the microwave signal power to signal conditioning device216. In the exemplary embodiment, subtractor220receives the microwave signal power and the detuned loading signal power, and calculates a difference between the microwave signal power and the detuned loading signal power.

Subtractor220transmits a signal representative of the calculated difference (hereinafter referred to as a “power difference signal”) to linearizer222. In the exemplary embodiment, an amplitude of the power difference signal is proportional, such as inversely or exponentially proportional, to a distance226defined between the object, such as a drive shaft104within electromagnetic field224, and probe202and/or emitter206(i.e., distance226is known as the object proximity). Depending on the characteristics of emitter206, such as, for example, the geometry of emitter206, the amplitude of the power difference signal may at least partially exhibit a non-linear relationship with respect to the object proximity.

In the exemplary embodiment, linearizer222transforms the power difference signal into a voltage output signal (i.e., the “proximity measurement signal”) that exhibits a substantially linear relationship between the object proximity and the amplitude of the signal. Moreover, in the exemplary embodiment, linearizer222transmits the proximity measurement signal to diagnostic system112(shown inFIG. 1) with a scale factor that is suitable for processing and/or analysis within diagnostic system112. In the exemplary embodiment, the proximity measurement signal has a scale factor of volts per millimeter. Alternatively, the proximity measurement signal may have any other scale factor that enables diagnostic system112and/or power system100to function as described herein.

FIG. 3is a cross-sectional view of probe202and probe housing208taken along area3(shown inFIG. 2). In the exemplary embodiment, probe housing208includes a probe cap300, an inner sleeve302, and an outer sleeve304. A substantially cylindrical cavity306is at least partially defined by cap300, inner sleeve302, and outer sleeve304. More specifically, probe cap300, inner sleeve302, and outer sleeve304are each substantially hollow, such that cavity306is at least partially defined by probe cap300, inner sleeve302, and outer sleeve304when probe housing208is assembled. Moreover, in the exemplary embodiment, an electromagnetic absorbent material307is applied into cavity306. More specifically, in the exemplary embodiment, electromagnetic absorbent material307is applied across at least a portion of inner sleeve302. In the exemplary embodiment, electromagnetic absorbent material307is applied to inner sleeve302via an adhesive. Alternatively, electromagnetic material absorbent material302may be applied to and/or impregnated onto inner sleeve302using any manner known in the art that enables probe202and/or sensor assembly110(shown inFIGS. 1 and 2) to function as described herein.

In the exemplary embodiment, probe cap300includes a substantially cylindrical end wall308that has an downstream surface310and an opposing upstream surface312. Probe cap300also includes a substantially annular sidewall314that circumscribes downstream surface310. Sidewall314includes an outer surface316and an opposing inner surface318that at least partially defines cavity306. In the exemplary embodiment, probe cap300is substantially symmetric with respect to a centerline axis320extending through probe housing208when probe housing208is assembled. More specifically, sidewall314is spaced substantially equidistantly about centerline axis320.

In the exemplary embodiment, probe cap300includes a threaded portion322that circumscribes inner surface318. Probe cap300, in the exemplary embodiment, is manufactured from a polyketone material, such as polyether ether ketone (PEEK), and/or any other thermoplastic material that enables probe cap300to be positioned within an industrial environment and/or within machine102without substantial degradation during operation of power system100(both shown inFIG. 1). Alternatively, probe cap300may be manufactured from any other material and/or compound that enables probe202to function as described herein.

In the exemplary embodiment, a ground conductor323is positioned within cavity306and positioned a distance360from emitter206. In the exemplary embodiment, the position of ground conductor323is adjustable such that distance360may vary. Moreover, in the exemplary embodiment, ground conductor323is a substantially annular ground plane and is positioned between outer sleeve304and data conduit204, within cavity306such that ground conductor323at least partially defines at least a portion of cavity306. More specifically, outer sleeve304is positioned about ground conductor323, and ground conductor323is positioned about data conduit204. Moreover, in the exemplary embodiment, ground conductor323extends substantially circumferentially about data conduit204. In the exemplary embodiment, ground conductor323is coupled to a conductive material or element (not shown) within outer sleeve304and/or within data conduit204that enables current to be transmitted from ground conductor323to ground. Ground conductor323, in the exemplary embodiment, is manufactured from any metallic material that enables ground conductor323to absorb current and transmit the current to ground.

Moreover, in the exemplary embodiment, ground conductor323includes an upstream surface327and a downstream surface329that is spaced a predetermined distance331from upstream surface327. In the exemplary embodiment, distance331is less than approximately 0.10 inches. Alternatively, distance331may be selected to be any length that enables probe202and/or assembly110to function as described herein. Moreover, in the exemplary embodiment, electromagnetic absorbent material307is applied across ground conductor323. In the exemplary embodiment, electromagnetic absorbent material307is applied to ground conductor323via an adhesive. Alternatively, electromagnetic material absorbent material307may be applied to and/or impregnated onto ground conductor323using any manner known in the art that enables probe202and/or assembly110to function as described herein. Moreover, in some embodiments, ground conductor323may be coupled to probe outer sleeve304and/or to data conduit204via welding, brazing, and/or via a threaded coupling. Alternatively, ground conductor323may be formed integrally with sleeve304and/or conduit204.

In the exemplary embodiment, inner sleeve302is annular and is sized to be at least partially received within probe cap300. Inner sleeve302includes an outer surface324and an opposing inner surface325. In the exemplary embodiment, inner sleeve302includes a threaded portion326that circumscribes outer surface324. Threaded portion326cooperates with probe cap threaded portion322to enable probe cap300and inner sleeve302to threadably couple together. In the exemplary embodiment, inner sleeve302is manufactured from a substantially non-conductive material, such as a thermoplastic material or any other plastic material. As such, inner sleeve302facilitates electromagnetically isolating emitter206from outer sleeve304and/or from any portion of machine102that is adjacent to probe202. Alternatively, inner sleeve302may be manufactured from any material and/or compound that enables probe202to function as described herein.

Outer sleeve304, in the exemplary embodiment, is annular and is sized to at least partially receive inner sleeve302therein. Outer sleeve304includes an inner surface328and an opposing outer surface330. In the exemplary embodiment, outer sleeve304includes an inner threaded portion332that circumscribes inner surface328, and an outer threaded portion334that circumscribes outer surface330. Inner threaded portion332cooperates with inner sleeve threaded portion326to enable inner sleeve302to be threadably coupled at least partially within outer sleeve304. Outer threaded portion334is sized and shaped to cooperate with a threaded bore (not shown) formed within a machine, such as machine102. As such, when probe202is assembled, probe202may be threadably coupled within machine102, such that probe202is positioned proximate to a machine component to be measured and/or monitored. Alternatively, outer sleeve304may be fabricated substantially smoothly and/or may not include outer threaded portion334such that probe202and/or outer sleeve304may be coupled to machine102via one or more bolts, brackets, and/or any other coupling mechanism that enables power system100(shown inFIG. 1) to function as described herein. Moreover, in the exemplary embodiment, ground conductor323is coupled to inner surface328.

In the exemplary embodiment, an emitter assembly336is positioned within probe housing208to form probe202. More specifically, in the exemplary embodiment, within emitter assembly336, emitter206is coupled to an emitter body338. Emitter body338includes downstream surface340and an opposing upstream surface342. In the exemplary embodiment, emitter body338is a substantially planar printed circuit board (PCB), and emitter206includes one or more traces and/or other conduits (not shown) that are formed integrally with, and/or coupled to, emitter body downstream surface340. Alternatively, emitter206and/or emitter body338may have any other construction and/or configuration that enables probe202to function as described herein. Moreover, in the exemplary embodiment, electromagnetic absorbent material307is applied across emitter body338. More specifically, electromagnetic absorbent material307is applied across emitter body downstream surface340. In the exemplary embodiment, electromagnetic absorbent material307is applied to emitter body downstream surface340via an adhesive. Alternatively, electromagnetic material absorbent material307may be applied to and/or impregnated onto emitter body downstream surface340using any manner known in the art that enables probe202and/or assembly110to function as described herein.

A coupling device344couples emitter body338and emitter206to a data or a signal conduit, such as to data conduit204for use in transmitting and receiving signals to and from signal processing device200(shown inFIG. 2). In the exemplary embodiment, coupling device344includes one or more bolts, brackets, welds, and/or any other coupling mechanism that enables emitter assembly336to function as described herein. Alternatively, data conduit204may be formed integrally with emitter206, emitter body338, and/or signal processing device200.

In the exemplary embodiment, in operation, probe cap300is positioned such that upstream surface312faces the object being measured and/or monitored and downstream surface310faces ground conductor323. As such, when forward propagating electromagnetic field224(shown inFIG. 2) is generated by emitter206, field224extends outwardly from emitter body upstream surface342and backward propagating field228extends outwardly from emitter body downstream surface340towards ground conductor323.

Moreover, during operation, backward propagating electromagnetic field228results in electromagnetic radiation (i.e., electromagnetic waves) being emitted within sensor assembly110. Further, when the loading is induced to emitter206, the variation in impedance levels between emitter206, data conduit204and signal processing device200(shown inFIG. 2) results in extraneous currents that are generated by emitter206and/or data conduit204. More specifically, in the exemplary embodiment, the extraneous currents that are generated by emitter206and/or data conduit204include at least one common mode current.

In the exemplary embodiment, when backward propagating electromagnetic field228is emitted, field228is reflected from ground conductor323such that backward propagating electromagnetic field228interacts with forward propagating electromagnetic field224. Moreover, the interaction between backward propagating electromagnetic field228and forward propagating electromagnetic field224is dependent on distance360. In the exemplary embodiment, the greater the value is for distance360, the less interaction there is between backward propagating electromagnetic field228and forward propagating electromagnetic field224. More specifically, for example, if distance360is substantially equal to a quarter wavelength for the detuned loading signal at an operating frequency of 3.3 GHz, then there is less interaction between backward propagating electromagnetic field228and forward propagating electromagnetic field224. Moreover, in the exemplary embodiment, the interaction enables backward propagating electromagnetic field228to be substantially reduced. Moreover, a portion of backward propagating electromagnetic field228that is not reflected from ground conductor323is absorbed by electromagnetic absorbent material307that is applied on ground conductor323.

As a result, the electromagnetic radiation within sensor assembly110(shown inFIG. 2) and/or within probe202is substantially reduced. More specifically, in the exemplary embodiment, the strength and amplitude of backward propagating electromagnetic field228are substantially reduced. Moreover, in the exemplary embodiment, as backward propagating electromagnetic field228is substantially reduced, the strength of the forward propagating electromagnetic field224is concentrated within a narrow range. In addition to substantially reducing backward propagating electromagnetic field228, the common mode current that is generated by emitter206and/or data conduit204is absorbed by ground conductor323. Ground conductor323transmits the common mode current to ground such that the electromagnetic radiation within sensor assembly and/or within probe202is further substantially reduced.

FIG. 4is a flow diagram illustrating an exemplary method400of assembling a sensor probe, such as sensor probe202(shown inFIGS. 1 and 2). An emitter206(shown inFIG. 2) is provided402, wherein emitter206is configured to generate at least one forward propagating electromagnetic field224(shown inFIG. 2) from at least one microwave signal and to generate at least one backward propagating electromagnetic field228(shown inFIG. 2). A data conduit204(shown inFIGS. 2 and 3) is coupled404to emitter206. A ground conductor323(shown inFIG. 3) that extends substantially circumferentially about data conduit204is provided406, wherein ground conductor323is configured to substantially reduce electromagnetic radiation within a sensor assembly110(shown inFIGS. 1 and 2). Moreover, an emitter body338(shown inFIG. 3) is coupled408to emitter206.

As compared to known sensor probes, the exemplary sensor probe described herein facilitates substantially reducing electromagnetic radiation within a sensor assembly in order to maintain a signal strength therein. In particular, the sensor probe described herein is configured such that at least one backward propagating electromagnetic field generated by the emitter is reflected to interact with a forward propagating electromagnetic field generated by the emitter. This interaction facilitates substantially reducing the electromagnetic radiation within the sensor assembly. Moreover, within the sensor assembly described herein, extraneous currents, such as common mode currents generated by the emitter and/or the data conduit, are channeled to ground. Channeling such extraneous currents to ground also facilitates in substantially reducing electromagnetic radiation within sensor assembly.

Exemplary embodiments of a sensor assembly and methods for reducing electromagnetic radiation are described above in detail. The methods and sensor assembly are not limited to the specific embodiments described herein, but rather, components of the sensor assembly and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein. For example, the sensor assembly may also be used in combination with other measuring systems and methods, and is not limited to practice with only the power system as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other measurement and/or monitoring applications.