Abstract:
In one embodiment, a method is provided. The method includes receiving a signal representative of an engine vibration transmitted via a knock sensor, wherein the knock sensor is disposed in an engine. The method additionally includes deriving an engine condition during operation of the engine. The method further includes correlating the engine condition to the signal via a lookup table, wherein the lookup table comprises at least a first column, and a second column, wherein the first column is representative of a knock sensor time window, and the second column is representative of a position range of a component of the engine, and communicating the engine condition.

Description:
BACKGROUND 
       [0001]    The subject matter disclosed herein relates to knock sensors, and more specifically, to knock sensor systems and method applied to component condition detection. 
         [0002]    Combustion engines will typically combust a carbonaceous fuel, such as natural gas, gasoline, diesel, and the like, and use the corresponding expansion of high temperature and pressure gases to apply a force to certain components of the engine, e.g., piston disposed in a cylinder, to move the components over a distance. Each cylinder may include one or move valves that open and close correlative with combustion of the carbonaceous fuel. For example, an intake valve may direct an oxidizer such as air into the cylinder, which is then mixed with fuel and combusted. Combustion fluids, e.g., hot gases, may then be directed to exit the cylinder via an exhaust valve. Accordingly, the carbonaceous fuel is transformed into mechanical motion, useful in driving a load. For example, the load may be a generator that produces electric power. It would be beneficial to improve detection of component conditions. 
       BRIEF DESCRIPTION 
       [0003]    Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below. 
         [0004]    In a first embodiment, a method is provided. The method includes receiving a signal representative of an engine vibration transmitted via a knock sensor, wherein the knock sensor is disposed in an engine. The method additionally includes deriving an engine condition during operation of the engine. The method further includes correlating the engine condition to the signal via a lookup table, wherein the lookup table comprises at least a first column, and a second column, wherein the first column is representative of a knock sensor time window, and the second column is representative of a position range of a component of the engine, and communicating the engine condition. 
         [0005]    In a second embodiment, a system includes an engine control system comprising a processor configured to receive a signal representative of an engine vibration transmitted via a knock sensor, wherein the knock sensor is disposed in an engine. The processor is further configured to derive an engine condition during operation of the engine. The processor is additionally configured to correlate the engine condition to the signal via a lookup table, wherein the lookup table comprises at least a first column, and a second column, wherein the first column is representative of a knock sensor time window, and the second column is representative of a position range of a component of the engine, and to communicate the engine condition. 
         [0006]    In a third embodiment, a tangible, non-transitory computer readable medium storing code is provided. The code is configured to cause a processor to receive a signal representative of an engine vibration transmitted via a knock sensor, wherein the knock sensor is disposed in an engine. The code is additionally configured to derive an engine condition during operation of the engine. The code is further configured to correlate the engine condition to the signal via a lookup table, wherein the lookup table comprises at least a first column, and a plurality of position columns, wherein the first column is representative of a knock sensor time window, and each of the plurality of position columns is representative of a position range for a component of the engine, and to communicate the engine condition. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
           [0008]      FIG. 1  is a block diagram of an embodiment of an engine driven power generation system in accordance with aspects of the present disclosure; 
           [0009]      FIG. 2  is a side cross-sectional view of an embodiment of a piston assembly in accordance with aspects of the present disclosure; 
           [0010]      FIG. 3  is an embodiment of an engine noise plot of data measured by the knock sensor shown in  FIG. 2  in accordance with aspects of the present disclosure; 
           [0011]      FIG. 4  is an embodiment of a combustion signature and a valve signature plotted over a first complete intake, compression, combustion and exhaust cycle in accordance with aspects of the present disclosure; and 
           [0012]      FIG. 5  is a flow chart of an embodiment of a process suitable for analyzing a vibration data and applying a lookup table. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
         [0014]    When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
         [0015]    The techniques described herein include the use of one or more knock sensor systems and methods that may detect a dynamic response of a various gas engine components during engine operations to derive conditions related to the components. For example, knock sensors signals related to a variety of engine components may be detected, including cylinder head components (e.g., cylinder head and gaskets), cylinder block components (e.g., cylinder block, cylinder sleeves), valves train components (e.g., valves, valve seats, valve stems), camshaft and drive components (e.g., camshaft, cam lobes, timing belts/chains, tensioners), piston components (e.g., pistons, piston rings, connection rods), crankshaft assembly components (e., crankshaft, engine bearings, flywheels), gear train components (e.g., gearbox, gears, output shaft), and so on. 
         [0016]    The knock sensor signals detected may then be compared, for example, by using a “look up” table to determine certain engine conditions that may have cause the knock sensor signals. Indeed, rather than applying techniques to separate knock from other noise data present in knock sensor signals, the techniques described herein embrace to “spurious” data and apply the data to determine a variety of engine conditions. By having a look up table of the engine&#39;s key components related to, for example, crank angle degree, the engine&#39;s key components can be indexed with respect to temporal windows related to crank angle degree to cross-check and estimate what key component is likely causing the noise. Accordingly, a more proactive engine maintenance and repair process may be provided. 
         [0017]    Turning to the drawings,  FIG. 1  illustrates a block diagram of an embodiment of a portion of an engine driven power generation system  10 . As described in detail below, the system  10  includes an engine  12  (e.g., a reciprocating internal combustion engine) having one or more combustion chambers  14  (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, or more combustion chambers  14 ). Though  FIG. 1  shows a combustion engine  12 , it should be understood that any reciprocating device may be used. An air supply  16  is configured to provide a pressurized oxidant  18 , such as air, oxygen, oxygen-enriched air, oxygen-reduced air, or any combination thereof, to each combustion chamber  14 . The combustion chamber  14  is also configured to receive a fuel  20  (e.g., a liquid and/or gaseous fuel) from a fuel supply  22 , and a fuel-air mixture ignites and combusts within each combustion chamber  14 . The hot pressurized combustion gases cause a piston  24  adjacent to each combustion chamber  14  to move linearly within a cylinder  26  and convert pressure exerted by the gases into a rotating motion, which causes a shaft  28  to rotate. Further, the shaft  28  may be coupled to a load  30 , which is powered via rotation of the shaft  28 . For example, the load  30  may be any suitable device that may generate power via the rotational output of the system  10 , such as an electrical generator. Additionally, although the following discussion refers to air as the oxidant  18 , any suitable oxidant may be used with the disclosed embodiments. Similarly, the fuel  20  may be any suitable gaseous fuel, such as natural gas, associated petroleum gas, propane, biogas, sewage gas, landfill gas, coal mine gas, for example. 
         [0018]    The system  10  disclosed herein may be adapted for use in stationary applications (e.g., in industrial power generating engines) or in mobile applications (e.g., in cars or aircraft). The engine  12  may be a two-stroke engine, three-stroke engine, four-stroke engine, five-stroke engine, or six-stroke engine. The engine  12  may also include any number of combustion chambers  14 , pistons  24 , and associated cylinders  26  (e.g., 1-24). For example, in certain embodiments, the system  10  may include a large-scale industrial reciprocating engine  12  having 4, 6, 8, 10, 16, 24 or more pistons  24  reciprocating in cylinders  26 . In some such cases, the cylinders  26  and/or the pistons  24  may have a diameter of between approximately 13.5-34 centimeters (cm). In some embodiments, the cylinders  26  and/or the pistons  24  may have a diameter of between approximately 10-40 cm, 15-25 cm, or about 15 cm. The system  10  may generate power ranging from 10 kW to 10 MW. In some embodiments, the engine  12  may operate at less than approximately 1800 revolutions per minute (RPM). In some embodiments, the engine  12  may operate at less than approximately 2000 RPM, 1900 RPM, 1700 RPM, 1600 RPM, 1500 RPM, 1400 RPM, 1300 RPM, 1200 RPM, 1000 RPM, 900 RPM, or 750 RPM. In some embodiments, the engine  12  may operate between approximately 750-2000 RPM, 900-1800 RPM, or 1000-1600 RPM. In some embodiments, the engine  12  may operate at approximately 1800 RPM, 1500 RPM, 1200 RPM, 1000 RPM, or 900 RPM. Exemplary engines  12  may include General Electric Company&#39;s Jenbacher Engines (e.g., Jenbacher Type 2, Type 3, Type 4, Type 6 or J920 FleXtra) or Waukesha Engines (e.g., Waukesha VGF, VHP, APG, 275GL), for example. 
         [0019]    The driven power generation system  10  may include one or more knock sensors  32  suitable for detecting engine “knock” and/or other run characteristics of the engine  12 . The knock sensor  32  may be any sensor configured to sense vibration caused by the engine  12 , such as vibration due to detonation, pre-ignition, and or pinging. The knock sensor  32  is shown communicatively coupled to a controller (e.g., a reciprocating device controller), engine control unit (ECU)  34 . During operations, signals from the knock sensors  32  are communicated to the ECU  34  to determine if knocking conditions (e.g., pinging), or other behaviors exist. The ECU  34  may then adjust certain engine  12  parameters to ameliorate or avoid the undesirable conditions. For example, the ECU  34  may adjust ignition timing and/or adjust boost pressure to avoid knocking. As further described herein, the knock sensors  32  may additionally detect other vibrations beyond knocking. Although the following techniques for analyzing component health are discussed in terms of a combustion engine, the same techniques may be applied to other reciprocating devices, such as a compressor. 
         [0020]    More specifically, the one or more knock sensors  32  may be used to detect a variety of signals and to correlate the signals based on crank angle degrees, noise signatures, or a combination thereof. For example, rather than filtering out “noise” in a signal so that the signal only detects knock, the knock sensor&#39;s  32  signal may be analyzed in its entirety to determine certain engine conditions. In one embodiment, the signal may be analyzed by using a look table described in more detail below, to determine if the noise detected is correlative to a certain crank angle or timing. If so, then the condition that caused the noise may be narrowed down to a small set or a single condition. Additionally or alternatively, a noise signature analysis may be performed, and the noise signature of the detected noise, in combination with the look up table, may narrow down the condition set even further. 
         [0021]      FIG. 2  is a side cross-sectional view of an embodiment of a piston assembly  36  having a piston  24  disposed within a cylinder  26  (e.g., an engine cylinder) of the reciprocating engine  12 . The cylinder  26  has an inner annular wall  38  defining a cylindrical cavity  40  (e.g., bore). The piston  24  may be defined by an axial axis or direction  42 , a radial axis or direction  44 , and a circumferential axis or direction  46 . The piston  24  includes a top portion  48  (e.g., a top land). The top portion  48  generally blocks the fuel  20  and the air  18 , or a fuel-air mixture, from escaping from the combustion chamber  14  during reciprocating motion of the piston  24 . 
         [0022]    As shown, the piston  24  is attached to a crankshaft  50  via a connecting rod  52  and a pin  54 . Also shown is a counterweight  55  of the crankshaft  50  useful in balancing a weight of a crank throw. The crankshaft  50  translates the reciprocating linear motion of the piston  24  into a rotating motion. As the piston  24  moves, the crankshaft  50  rotates to power the load  30  (shown in  FIG. 1 ), as discussed above. As shown, the combustion chamber  14  is positioned adjacent to the top land  48  of the piston  24 . A fuel injector  56  provides the fuel  20  to the combustion chamber  14 , and an intake valve  58  controls the delivery of air  18  to the combustion chamber  14 . An exhaust valve  60  controls discharge of exhaust from the engine  12 . However, it should be understood that any suitable elements and/or techniques for providing fuel  20  and air  18  to the combustion chamber  14  and/or for discharging exhaust may be utilized, and in some embodiments, no fuel injection is used. In operation, combustion of the fuel  20  with the air  18  in the combustion chamber  14  cause the piston  24  to move in a reciprocating manner (e.g., back and forth) in the axial direction  42  within the cavity  40  of the cylinder  26 . 
         [0023]    During operations, when the piston  24  is at the highest point in the cylinder  26  it is in a position called top dead center (TDC). When the piston  24  is at its lowest point in the cylinder  26 , it is in a position called bottom dead center (BDC). As the piston  24  moves from top to bottom or from bottom to top, the crankshaft  50  rotates one half of a revolution. Each movement of the piston  24  from top to bottom or from bottom to top is called a stroke, and engine  12  embodiments may include two-stroke engines, three-stroke engines, four-stroke engines, five-stroke engine, six-stroke engines, or more. 
         [0024]    During engine  12  operations, a sequence including an intake process, a compression process, a power process, and an exhaust process typically occurs. The intake process enables a combustible mixture, such as fuel and air, to be pulled into the cylinder  26 , thus the intake valve  58  is open and the exhaust valve  60  is closed. The compression process compresses the combustible mixture into a smaller space, so both the intake valve  58  and the exhaust valve  60  are closed. The power process ignites the compressed fuel-air mixture, which may include a spark ignition through a spark plug system, and/or a compression ignition through compression heat. The resulting pressure from combustion then forces the piston  24  to BDC. The exhaust process typically returns the piston  24  to TDC while keeping the exhaust valve  60  open. The exhaust process thus expels the spent fuel-air mixture through the exhaust valve  60 . It is to be noted that more than one intake valve  58  and exhaust valve  60  may be used per cylinder  26 . 
         [0025]    The engine  12  may also include a crankshaft sensor  62 , one or more knock sensors  32 , and the engine control unit (ECU)  34 , which includes a processor  64  and memory  66  (e.g., non-transitory computer readable medium). The crankshaft sensor  62  senses the position and/or rotational speed of the crankshaft  50 . Accordingly, a crank angle or crank timing information may be derived. That is, when monitoring combustion engines, timing is frequently expressed in terms of crankshaft  50  angle. For example, a full cycle of a four stroke engine  12  may be measured as a 720° cycle. The one or more knock sensors  32  may be a Piezo-electric accelerometer, a microelectromechanical system (MEMS) sensor, a Hall effect sensor, a magnetostrictive sensor, and/or any other sensor designed to sense vibration, acceleration, sound, and/or movement. In other embodiments, sensor  32  may not be a knock sensor in the traditional sense, but any sensor that may sense vibration, pressure, acceleration, deflection, or movement. 
         [0026]    Because of the percussive nature of the engine  12 , the knock sensor  32  may be capable of detecting engine vibrations and/or certain “signatures” related to a variety of engine conditions even when mounted on the exterior of the cylinder  26 . The one or more knock sensors  32  may be disposed at many different locations on the engine  12 . For example, in  FIG. 2 , one knock sensors  32  is shown on the head of the cylinder  26 . In other embodiments, one or more knock sensors  32  may be used on the side of the cylinder  26 . Additionally, in some embodiments, a single knock sensor  32  may be shared, for example, with one or more adjacent cylinders  26 . In other embodiments, each cylinder  26  may include one or more knock sensors  32  on either or both sides of a cylinder  26 . The crankshaft sensor  62  and the knock sensor  32  are shown in electronic communication with the engine control unit (ECU)  34 . The ECU  34  includes a processor  64  and a memory  66 . The memory  66  may store non-transitory code or computer instructions that may be executed by the processor  64 . The ECU  34  monitors and controls and operation of the engine  12 , for example, by adjusting spark timing, valve  58 ,  60  timing, adjusting the delivery of fuel and oxidant (e.g., air), and so on. 
         [0027]    Knock sensors  32  are used to detect engine knock. Engine knock is the premature combustion of fuel outside the envelope of normal combustion. In some cases, the ECU  34  may attempt to reduce or avoid engine knock when it occurs by adjusting the operating parameters of the engine. For example, the ECU  34  may adjust the air/fuel mix, ignition timing, boost pressure, etc. in an effort to reduce or avoid engine knock. However, knock sensors may also be used to detect other vibrations in an engine unrelated to engine knock. 
         [0028]      FIG. 3  is an embodiment of a raw engine noise plot  68  derived (e.g., by the ECU  34 ) of noise data measured by a single knock sensor  32  mounted on a single cylinder  26  in which x-axis  70  is time and the y-axis  72  is raw noise amplitude. In the depicted embodiment, an amplitude curve  74  of the knock sensor  32  signal is shown. That is, the raw signal  74  includes amplitude measurements of vibration data (e.g., noise, sound data) sensed via the knock sensor  32  and plotted against time. It should be understood that this is merely a plot  68  of a sample data set, and not intended to limit plots generated by the ECU  34 . It should also be understood that plot  68  is of a signature from one knock sensor  32  mounted to one cylinder  26 . In other embodiments there may be multiple signatures from multiple knock sensors mounted to multiple cylinders, e.g., mating cylinders. The raw signal  74  may then be further processed, as described in more detail below, including via the use of a look up table and/or signature analysis. 
         [0029]    With respect to signature analysis, as shown in  FIG. 4 , signals can be filtered into a combustion signature  76  and a valve signature  78 . Events can then be derived from the signatures and the timing of those events checked via look up table(s). Once data from the one or more knock sensors  32  is collected, one or more filters may be applied to the data to derive a combustion signature  76  (i.e., noise attributable to combustion events) and a valve signature  78  (i.e., noise attributable to valve  58 ,  60  movement). The combustion signature  76  and valve signature  78  may be derived by applying filters, fast Fourier transforms (FFT), or applying other digital signal processing (DSP) techniques to the sampled data. For example, the ECU  34  may derive the combustion signature  76  by applying a low pass filter at 1200 Hz or a band pass filter from 0.5 Hz to 1200 Hz. The valve signature may be derived using a band pass filter from 12 kHz to 18 kHz.  FIG. 4  is an embodiment of a sample plot  82  of a combustion signature  76  and a valve signature  78  over a first complete intake, compression, and combustion and exhaust cycle. The x-axis  84  is shown as time in seconds, but may also be shown as crank angle. The y-axis  86  on the left corresponds to the valve signature  78 , and the y-axis  88  on the right corresponds to the combustion signature  76 . Each of the y-axes  86 ,  88  represents the amplitude of the corresponding noise signature  76 ,  78 . Depending upon the measurement technique and the preference of the user, the units may be dB, volts, or some other unit). Note that the scales of the y-axes  86 ,  88  may be different because the amplitudes of the two signatures  76 ,  78  are likely to be different.  FIG. 4  is illustrative of data that may be undergoing data processing, for example, via a process described in more detail with respect to the figures below. The data for  FIG. 4  may include data transmitted via the knock sensor  32  and the crank angle sensor  62  once the ECU  34  has derived a combustion signature  76  and a valve signature  78  from the data using digital signal processing (DSP) techniques. Furthermore, for the sake of clarity, only a single combustion signature and a single valve signature are shown in  FIG. 4 . It should be understood, however, that the same or similar processing may be performed on more than one knock sensor  32  mounted to more than one cylinder. 
         [0030]    The combustion signature  76  includes significant combustion events, such as peak firing pressure (PFP) of both the measured cylinder  26 , and a mating cylinder  80  (i.e., the cylinder in the engine that is 360 degrees out of phase with the measured cylinder  26 ). The valve signature  78  includes the closing of the intake valve  58  and exhaust valve  60 . Some combustion events, such as PFP (of both the measured cylinder  26  and the mating cylinder  80 ), may appear in both the combustion signature  76  and the valve signature  78 .  FIG. 4  shows slightly more than one complete combustion cycle, or 720 degrees of rotation (two complete revolutions) at the crankshaft  50 . Each cycle includes intake, compression, combustion, and exhaust. 
         [0031]    In one example, the signatures  76 ,  78 , and/or the raw signal  74  may be processed to determine if any abnormal conditions exist. In one embodiment, the signatures  76 ,  78 , and/or the raw signal  74  may be compared to a baseline, and the comparison used to determine that sufficient differences exist such that a condition affecting engine performance is occurring. The comparison between the signatures  76 ,  78 , and/or the raw signal  74  and the baseline include a crank angle degree or timing comparison. That, is differences between the signatures  76 ,  78 , and/or the raw signal  74  and the baseline may be ascertained by comparison based on when in the engine combustion cycle the signatures  76 ,  78 , and/or the raw signal  74  was captured, which may be correlative with the position or crank angle of the crank  50 . The baseline may be derived by observing normal operations of the engine  12  over the course of multiple combustion cycles. 
         [0032]    In another embodiment, the determination that an abnormal condition of some sort exists may be made by other techniques, such as lubricant analysis, emissions analysis, wear debris detection, and the like. Regardless of the techniques used to determine that some sort of abnormality is occurring, including baselining the signatures  76 ,  78 , and/or the raw signal  74 , the techniques described herein may additionally or alternatively aid in determining what component or components may be involved. More specifically, the techniques described herein may apply a look up table to determine component(s) of the engine  12  involved in the current condition. 
         [0033]    In one embodiment, the look up table for a twelve-cylinder embodiment of the engine  12  may include a first Knock sensor window “open”, followed by one or more position columns. The position columns may include cam position (degrees), crank position (degrees), #1 Right Cylinder Piston Position (inches from TDC), #1 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #6 Left Cylinder Piston Position (inches from TDC), #6 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #5 Right Cylinder Piston Position (inches from TDC), #5 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #2 Left Cylinder Piston Position (inches from TDC), #2 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #3 Right Cylinder Piston Position (inches from TDC), #3 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #4 Left Cylinder Piston Position (inches from TDC), and #4 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees. 
         [0034]    The Knock sensor window “open” column may refer to a time window (e.g., time range) or crank angle window (e.g., angle range) at which a particular sensor  32  is more suited to derive engine  12  conditions, based on the one or more position columns. For example, the knock sensor  32  disposed in the #1 right cylinder  26  may be more suitable at a window or range when the camshaft position (e.g., crank position (degrees) column) is between 0 and 15 degrees. Likewise, the remainder columns crank position (degrees), #1 Right Cylinder Piston Position (inches from TDC), #1 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #6 Left Cylinder Piston Position (inches from TDC), #6 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #5 Right Cylinder Piston Position (inches from TDC), #5 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #2 Left Cylinder Piston Position (inches from TDC), #2 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #3 Right Cylinder Piston Position (inches from TDC), #3 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #4 Left Cylinder Piston Position (inches from TDC), and #4 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees may include data related to when a particular knock sensor  32  (e.g., #1 right, #1 left, #2 right, #2 left, #3 right, #3 left, #4 right, #4 left, #5 right, #5 left, #6 right, #6 left) is more effective at certain positions. 
         [0035]    The look up table may be created, for example, to correlate noise received via the knock sensors  32  and corresponding position columns, with one or more engine  12  conditions, such as conditions affecting cylinder  26  head components (e.g., cylinder head and gaskets), cylinder  26  block components (e.g., cylinder block, cylinder sleeves), valve  58 ,  60  train components (e.g., valves, valve seats, valve stems), camshaft  50  and drive components (e.g., camshaft, cam lobes, timing belts/chains, tensioners), piston  24  components (e.g., pistons, piston rings, connection rods), crankshaft  50  assembly components (e., crankshaft, engine bearings, flywheels), gear train components (e.g., gearbox, gears, output shaft), and so on. In one embodiment, the crankshaft sensor  62  may aid in the correlation, for example, by additionally providing for crankshaft  50  position data (e.g., crank position (degrees) column) By correlating which of a particular knock sensor  32  (e.g., #1 right, #1 left, #2 right, #2 left, #3 right, #3 left, #4 right, #4 left, #5 right, #5 left, #6 right, and/or #6 left knock sensor  32 , where the number and position corresponds to a cylinder  32  number and position of, for example, the  12  cylinder embodiment of the engine  12 ), and when the knock sensor  32  detected the unusual or unexpected noise, the techniques described herein may provide for an estimate of which component is likely causing the unexpected noise. In one embodiment, more than one look up table may be used, each table correlating noise to a specific component, set of components, engine condition, set of engine conditions, or a combination thereof. In another embodiment, the set of engine  12  conditions correlative to the position columns and the Knock sensor window “open” column may be stored as additional Condition columns in the lookup table(s). Accordingly, the techniques described herein may enable a real time detection of engine  12  conditions through, for example, existing knock sensors  32 , which may result in proactive engine maintenance and repair processes. 
         [0036]      FIG. 5  is a flow chart depicting a process  150  suitable for analyzing vibration data via the knock sensors  32  and lookup table(s). The process  150  may be implemented as computer code or instructions executable via the processor  64  and stored in the memory  66 . In the depicted embodiment, the process  150  may create (block  152 ) one or more lookup tables  154 . As mentioned above, the look up table(s)  154  may be created to correlate noise received via the knock sensors  32  and corresponding position columns, with one or more engine  12  conditions, such as conditions affecting cylinder  26  head components (e.g., cylinder head and gaskets), cylinder  26  block components (e.g., cylinder block, cylinder sleeves), valve  58 ,  60  train components (e.g., valves, valve seats, valve stems), camshaft  50  and drive components (e.g., camshaft, cam lobes, timing belts/chains, tensioners), piston  24  components (e.g., pistons, piston rings, connection rods), crankshaft  50  assembly components (e., crankshaft, engine bearings, flywheels), gear train components (e.g., gearbox, gears, output shaft), and so on. 
         [0037]    In one embodiment of a twelve-cylinder engine  12 , the lookup table(s)  154  may include a Knock sensor window “open” column followed by one or more position columns. The position columns may include: cam position (degrees), crank position (degrees), #1 Right Cylinder Piston Position (inches from TDC), #1 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #6 Left Cylinder Piston Position (inches from TDC), #6 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #5 Right Cylinder Piston Position (inches from TDC), #5 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #2 Left Cylinder Piston Position (inches from TDC), #2 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #3 Right Cylinder Piston Position (inches from TDC), #3 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #4 Left Cylinder Piston Position (inches from TDC), and #4 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0. 
         [0038]    Each row of the lookup table(s)  154  may include a specific knock sensor  32  (e.g., #1 right, #1 left, #2 right, #2 left, #3 right, #3 left, #4 right, #4 left, #5 right, #5 left, #6 right, and/or #6 left sensor  32 ) in the Knock sensor window “open” column and corresponding position values for the position columns. In one embodiment, a test bed engine  12  may be instrumented and used to create the lookup table(s)  154 . For example, noise related to the one or more engine  12  conditions listed above may be captured and analyzed, and the columns of the lookup table(s)  154  associated with the noise. In use, the knock sensor(s)  32  may sense (block  156 ) engine noise during engine  12  operations. Certain noises, such as unusual noises, may be found, for example, by using the baselining and/or signature techniques described above, or by other techniques. The noises may then be correlated by applying (block  158 ) the lookup table(s)  154 . For example, the relevant knock sensor(s)  32  that detect the noise and/or the signals from the crankshaft sensor  62  may be used to derive values for the position columns of the table(s)  154 . Based on the noise detected and/or the position of certain components (e.g., derived by using the position columns of the lookup table(s)  154 ), certain engine conditions may be derived (block  160 ). 
         [0039]    For example, based on cam position (degrees), crank position (degrees), #1 Right Cylinder Piston Position (inches from TDC), #1 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #6 Left Cylinder Piston Position (inches from TDC), #6 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #5 Right Cylinder Piston Position (inches from TDC), #5 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #2 Left Cylinder Piston Position (inches from TDC), #2 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #3 Right Cylinder Piston Position (inches from TDC), #3 Right Cylinder Counterweight Position Angle from Highest Point where Highest point=0 degrees, #4 Left Cylinder Piston Position (inches from TDC), and/or #4 Left Cylinder Counterweight Position Angle from Highest Point where Highest point=0, it may be possible to more easily narrow down (or fully derive) (block  160 ) that the noise captured by the knock sensor(s)  32  is due to a certain engine condition, or subset of engine conditions. 
         [0040]    The process  150  may then communicate (block  162 ) the derived engine  12  conditions. For example, the process  150  may display the one or more engine  12  conditions in a display communicatively coupled to the ECU  34 , set an error code (e.g., controller area network [CAN] code, on-board diagnostics II [OBD-II] code), set an alarm or an alert, and so on. By correlating noise via lookup table(s)  154 , the techniques described herein may enhance engine operations and maintenance processes. 
         [0041]    Technical effects of the invention include detecting engine vibrations via certain sensors, such as knock sensors. Certain lookup table(s) may be created, suitable for associating one or more knock sensor “windows” with one or more positions of certain engine components. The vibrations are correlated, via the one or more lookup tables and/or crankshaft sensor data, and certain engine conditions may be detected. 
         [0042]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.