Abstract:
The invention relates to a system for real-time monitoring of motile lubricants within the presently common reciprocating engine. A sensor array is fully submerged (or partially submerged) within the lubricant system fluid, for example, oil. The fluid property monitoring is accomplished by multiple sensors acting in unison to provide data to a remote processing and display portion of the system. The system allows for the unified data acquisition and real-time comparison by providing both a physical sensor unit with embedded multiple sensors of multiple types as well as multiple DSP (Digital Signal Processing) or microcontroller modules acting in parallel to provide best-fit results for purposes of real-time monitoring high-temperature motile lubricants for property degradation (namely viscosity and foreign particulate detection) and particulate accumulation.

Description:
[0001]    This application claims the benefit of pending U.S. provisional patent application No. 61/118,056, which was filed on Nov. 26, 2008, and is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention encompasses embodiments related generally to automotive reciprocating engines, transmissions, and aircraft. Such closed systems require constant internal lubrication flow to protect the internal moving parts from the inherent friction. The lubricants are typically carbon-based or related synthetics, which over time vary or decay due to the system environment. The key component of the lubricant is the property of viscosity, which varies over time, temperature, and use. In such systems, particulates of metallic and non-metallic variety tend to accumulate over time and use. The present invention provides a real-time user notification system for early warning notification when conditions reach unfavorable levels that can result in damage to the system. 
       BACKGROUND OF THE INVENTION 
       [0003]    The field of endeavor is related to the automobile industry and in particular to engines and large scale mechanical devices, which utilize motile lubricating fluids in high-temperature environments in which real-time monitoring of the changing fluid properties as well as the detection of metallic particulates would be beneficial. Existing systems have two main problems influencing the implementation of such a solution. First, the environmental temperatures are often in excess of 150 degrees Celsius. These temperature extremes require that special concerns be addressed for the use of various electronic sensors and electrically active elements to support those sensors. The temperature extremes are such that many times no viable solution exists. Second, a sensor that is continually and fully submerged (or partially submerged) within the high-temperature lubricants is desired. However, the temperature and the properties of the liquids make it difficult to protect a sensor or sensor array from degradation. 
         [0004]    To monitor engine oil properties, the following data points are needed: temperature of lubricant, absolute pressure, and viscosity. Viscosity describes a fluid&#39;s internal resistance to flow and may be thought of as a measure of fluid friction. The invention uses thermocouples and common pressure sensors to acquire the data points since viscosity is a function of temperature and pressure, which are properties that define the behavior of a fluid. In addition to detecting these data points, it is critical to detect metallic particles, which can damage critical moving parts. Accordingly, the invention also uses a simple magnet and an associated Hall sensor to attract and detect metallic particles that may be present in the fluid. An added or optional feature of the detection method may include inductive coils that are incorporated into the design to generate electrical signals that can also be affected by the presence of moving metallic particles. 
         [0005]    Monitoring viscosity requires a method of creating a signal substantially related to the fluidic friction of the engine lubricant. The invention fulfills this requirement with a simple method that includes placing two GaAs Hall-based sensor elements within the fluidic lubricant in such locations where the fluid is flowing and not stagnant when in use. These GaAs Hall-based sensor elements are substantially similar and located in close proximity to one another within a flow path of the lubricant. With such a configuration, many issues that can generate errors in data collection can be ignored for purposes of simplifying related mathematics and decreasing overall production costs. According to one embodiment of the invention, there is one difference between the two GaAs Hall-based sensor elements. That difference is in the shapes of the sensor elements. In one embodiment, one sensor element has a rotor with teeth substantially like those found in a paddle wheel or gear. The rotor with teeth rotates when appropriately placed within the lubricant flow path in a manner substantially related to the velocity of the lubricant. The viscosity of the lubricant has a negligible effect on the rotation of the rotor with teeth. The other sensor element has a substantially smooth rotor that rotates in a similar fashion as the rotor with teeth. Due to the different (smooth) shape of the rotor, the rotational rate of the smooth rotor is substantially affected by the friction of the fluid, which is directly related to the lubricant viscosity. The rotors of the two sensor elements rotate at different velocities and thus generate electrical signals that their associated GaAs Hall sensors detect due to magnetic field variations. The difference between these two signals is related to the lubricant viscosity. The rotor with teeth will always spin faster than the toothless rotor due primarily to the different effects of the fluidic friction (viscosity) on the rotors. Plotting this difference along with the local temperature and pressure and comparing these plots against documented lubricant viscosity tables show that the two provide substantially similar results. Due to slight errors in conversion, the difference should be substantially linear and thus allow for this simplistic design to create a useful manner of plotting viscosity with an electrical simplistic design and for reduced manufacturing complexity and cost. 
         [0006]    Due to environmental factors, namely temperature, the sensor components located within the engine lubricant must be able to withstand conditions that are, at present, technically difficult to withstand. The invention employs sensor components that are robust under such conditions. For example, one embodiment of the invention uses thermocouples that measure temperature, pressure sense elements that are based on thick film resistor design, and Hall sensors. The Hall sensors are GaAs-based and thus have properties that allow the sensors to withstand high-temperature environments. Such elements have shown that they can function within this extreme environment in such a manner as to relate useful data. One embodiment of the invention utilizes moving mechanical parts to create signals related to fluidic velocity and viscosity. At present, such method proves effective and provides a simple solution. However, the invention is not limited to this method. GaAs Hall-based fluidic viscosity and velocity signals can be created without moving parts and could also be utilized within the scope of the invention. 
       SUMMARY 
       [0007]    The present invention provides for the real-time monitoring of flowing fluids associated with closed high-temperature environments present within or associated with internal combustion engines. One embodiment of the invention monitors flowing oil-based lubricants normally used with internal combustion engines for purposes of lubrication. Another embodiment of the invention monitors related application fluids, such as transmission fluids and glycerin-based coolants, such as anti-freeze. One aspect of the invention involves monitoring, in real time, the degradation of the monitored motile fluid due to heat, pressure, and mechanical means. Another aspect of the invention involves the detection of the presence of known harmful particulates, such as metal, within the lubricant monitored. Another aspect of the invention involves fluid monitoring with a sensor module that is continually and fully submerged or partially submerged within the lubrication fluid. The present invention addresses problems in the prior art that arise from several properties related to the environment, such as high heat and temperature constraints. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic view of a real-time in-engine lubrication system according to one embodiment of the invention. 
           [0009]      FIG. 2  is a block diagram of an in-engine lubricant sensor assembly according to one embodiment of the invention. 
           [0010]      FIG. 3  is a block diagram of a display and processing portion of a system according to one embodiment of the invention. 
           [0011]      FIG. 4  is a block diagram of DSP modules incorporated within a display and processing portion of a system according to one embodiment of the invention. 
           [0012]      FIG. 5  is a schematic view of both a viscosity sensor and a velocity sensor mounted within a sensor assembly according to one embodiment of the invention. 
           [0013]      FIG. 6  is a schematic view of both a viscosity sensor and a velocity sensor according to one embodiment of the invention. 
           [0014]      FIG. 7  is a Fluidic Velocity and Viscosity Sensor Element Output Generalized in both graphic and equation format. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0015]    The exemplary embodiment shown in  FIG. 1  comprises two main physical parts—the sensor element or assembly  100  and the display unit  120 . Both parts comprise mechanical units and software/firmware elements working in concert to collect, process, and display the required data. 
         [0016]    The sensor element  100  comprises several physical units and is designed to be installed within the associated engine or related mechanical device, which requires constant fluidic-based lubrication. According to one embodiment of the invention, the sensor element  100  comprises an overall form factor of that of a disc-shaped insert placed within the engine block and the oil filter. The sensor assembly  100  comprises a series of stacked discs  150 , which allow for the physical manufacture of the complete assembly. One side of the sensor assembly  100  is designed to be mounted on the engine block  151  and provides inlet and outlet flow paths substantially similar to those already present in the attached oil filter, which is separated from the engine by the inserted sensor assembly  100 . The opposite side of the sensor assembly  100  is designed to mate with the oil filter  152  in such a way as to substantially copy the features of the engine block that are normally attached to the oil filter. The sensor element  100  is positioned to allow lubricants moving to and from the oil filter to pass through the sensor element  100  so that the sensor element  100  has access to the moving fluid during the operation of the system to which the sensor element is attached. Elements  101 ,  104 ,  111 ,  105 ,  106 ,  102 , and  107  must be submerged during operation. Element  101  is a bimetal thermocouple used to provide an electrical signal substantially related to the internal temperature of the lubricant fluid in which the sensor assembly  100  is submerged. This electrical signal is electrically coupled to electronic circuitry  109  of the sensor assembly  100 . Element  111  is an absolute pressure sensor element electrically coupled to the electronic circuitry  109  and provides an electrical signal substantially related to the internal pressure of the lubricating fluid. Element  104  is a Hall sensor, which, in association with element  107 , which is a magnet, creates an electrical signal substantially reflecting the presence of metallic particles passing between the magnet  107  and the Hall sensor  104 . The Hall sensor  104  subsequently provides an electrically coupled signal to the electronic circuitry element  109 . Element  102  is a bimetal thermocouple used to provide an electrical signal substantially related to the internal temperature of the lubricant fluid at a point closer to the external portion of the sensor assembly  100 , which is submerged in the lubricant fluid. Thermocouple  102 , in conjunction with thermocouple  101 , generates differential temperature-based electric signals. Element  103  is a bimetal thermocouple used to provide an electrical signal substantially related to the external temperature of the sensor assembly  100 . Thermocouple  103  can provide differential signals to thermocouples  101  and  102 , as well as be used as a referent to both. Two inductive coils  108  are concentrically located around the bolt-shaped sensor assembly  100  for purposes of providing substantially inductive responsive electrical signals to the electronic circuitry  109  of the sensor assembly  100 . Element  105  is a Hall-based fluid velocity sense element ( FIG. 5 ) used to provide to the electronic circuitry  109  of the sensor assembly  100  an electrical signal substantially related to the fluidic lubricant&#39;s fluid velocity. Element  106  is a Hall-based fluid viscosity sense element ( FIG. 5 ) used to provide to the electronic circuitry  109  of the sensor assembly  100  an electrical signal substantially related to the fluidic lubricant&#39;s fluid viscosity. Both sense elements  105  and  106  reside partially within and adjacent to a lubricant path channel  112 . According to one embodiment of the invention, the lubricant channel  112  takes the form of a machined tunnel passing through the discs  150  of the sensor assembly  100 . Also, within the flow path  112  is the magnetic source  107  and associated Hall sensor  104 . According to this design, any ferrous metallic particles that are suspended within the lubricant are deposited in the flow path  112  in close proximity to magnet element  107 . Thus, there is a higher probability that the Hall effect element  104  will be affected by those deposited metallic particles. The location of the magnet  107  and Hall sensor  104  is such that they help provide a collection point for these errant metallic materials in an attempt to reduce their travel back into the lubricant system being monitored. 
         [0017]    The electronic circuitry  109  of the sensor assembly  100  collects electrical data signals from the above-mentioned sense elements, draws its power from electrical conductors  122 , and transmits its output electric signals via wired connection  122  or wireless communication means  110 . The electrical circuitry  109  comprises common electronic signal amplification means, filtering means, and data transformation means. As shown in  FIG. 2 , data collection involves the collection of three types of data: Hall sensor data, temperature and pressure sensor data, and inductive sensor data. Signals from Hall velocity sensor element  105  and Hall viscosity sensor element  106  are represented by blocks  201 . Signals from the Hall-based particulate detection element  104  is represented block  202 . The electrical signals represented by blocks  201  and  202  are electrically manipulated to filter unwanted signals, such as noise, and amplified at block  203  to produce electrical signals compatible with subsequent processing. Block  204  represents the electrical signal generated by the innermost thermocouple  101 . Block  205  represents signals from an optional thermocouple with characteristics substantially similar to those of element  101 . The optional thermocouple can be used to provide additional information that may be required by a particular application. Block  206  represents the data provided by optional pressure sensor element  111 . In general, pressure can be ignored since most internally lubricated systems maintain their internal pressure via other means and, in most cases, this makes pressure essentially become a constant for the purpose of subsequent calculations. Blocks  207  and  208  represent signals from the internal temperature reference thermocouple  102  and the external temperature reference thermocouple  103 , respectively. The electrical signals represented by block elements  204 ,  205 ,  206 ,  207 , and  208  are electrically manipulated to filter unwanted signals, such as noise, and amplified at block  209  to produce electrical signals compatible with subsequent processing. Signals from the two inductive coils  108  are represented by blocks  210 . These electrical signals are electrically manipulated to filter unwanted signals, such as noise, and amplified at block  211  to produce electrical signals compatible with subsequent processing. 
         [0018]    Block  212  represents an embedded microcontroller of the sensor assembly  100 . At this block, the three data types are collected and formatted for transmittal to external elements. The data from the microcontroller  212  is then passed to the communications processing portion  214  of the circuitry and, based on whether wired data transmittal wireless data transport is required, data passes to block elements  215  or  213 , respectively. At this point, the data passes from the sensor element  100  and into the display unit  120  of the system as depicted by block element  216 . Further data processing is shown in  FIG. 3 . 
         [0019]    Referring again to  FIG. 1 , the lubrication system display unit  120  is used to display data in a manner useful to the application. In general terms, there are three types of displays: errors and alerts, statistical parametric data display related to the individual sensed data points, and graphical user interfaces used to interact with the system user and thereby configure data display behaviors. The display unit  120  directly interacts with the reception antenna  121  and the wired power and data connection  122 . Both the sensor element  100  and display unit  120  can receive power from battery element  123  or other useful power sources. 
         [0020]      FIG. 3  depicts the electrical function and data manipulation of the display unit  120 . Data enters the display unit  120  at block element  300 . This data can be from either the wireless data source  121  or the wired means  122 . Block elements  301  and  302  convert and manipulate incoming wired and wireless data, respectively, to produce signals that will be useful at block element  303 . Block element represents the point at which raw data is formatted to be subsequently passed to DSP processing elements  304  through  308 . As will be discussed in more detail below with reference to  FIG. 4 , these DSP elements handle their data the same way. DSP processing at blocks  304  through  308  is divided according to the type of data. Such parallel segregation allows for all data types to essentially generate the same kind of outputs, which can then be passed to block element  309  for purposes of detecting formalized errors and for purposes of real-time characterization at block element  310 . The DSP Hall flow calculator  304  is responsible for decoding the data from sensors  105  and  106  and generating a digital signal directly reflecting the lubricant viscosity. DSP inductor flow calculator  305  takes data from coils  108  and generates a digital data signal directly related to the variations between the coils. DSP Temperature Differential Calculator  306  creates a digital output based on signals from temperature input elements  101 ,  102 ,  103  and pressure element  111 . DSP Hall Particulate Signature Detector  307  creates a digital output based on the variations caused by metallic particles affecting Hall element  104 . DSP Inductor Particulate Signature Detector  308  creates a digital output based on the variations caused by metallic particles affecting inductor elements  108 . 
         [0021]    The Error State Detector  309  receives signals, and those defined as errors are formatted and displayed at Error Display and Alerts  312 . The errors include, but are not limited to, temperature under and over alerts, data missing errors, metallic particles detected, and DSP calculation errors. Real Time Characteristic Data  310  receives the detailed DSP digital data from DSP elements  304  through  308  and formats that data to produce useful displays and trend plots for display at Graphic Display  313 . User input  311  is facilitated by push buttons and other means facilitated by the display unit  120 . The inputs are used to adjust configurations and determine what displays are used at Configuration/Display Manager  314 . Configuration at this point affects the type and form of the data displayed at the Configuration Display  315  as well as the displays  312  and  313 . Error Display and Alerts  312  can comprise, for example, LED illumination, piezo sounders, or LCD displays. Graphic Display  313  can comprise, for example, trend plots showing various generated data points or simple numeric displays representing the resultant data. Data points available for display can include, but are not limited to, calculated viscosity, calculated fluid velocity, internal lubricant temperature and pressure, temperature variations, external temperature, differential temperature, particulate detection, and particulate signature decode representing detected metal types. 
         [0022]    DSP elements  304 - 308  will now be described with reference to  FIG. 4 . Raw digital data from block  303  enters a particular DSP processor at block  400 . Data is filtered at block  401  to retain only that data necessary for DSP. That data subsequently goes through stage  1  data reduction at block  402 . At this point, data filtering and initial processing is accomplished for purposes of determining at block  403  if the data is valid. If the data is not valid, the appropriate error state flag at block  408  is set and an error signal is sent at block  413  for detection of the error at block  309 . If data at element  403  is valid, it moves through Stage 2-N Data processing at block  404 , where “N” represents multiple sequential stages of data processing. Once data is processed at block  404 , errors local to the stage are checked at block  409 . If errors are present, the process flow continues to block  408 . If no errors occur, data continues to Stage 2-N Reduced Data Available at block  405 . If no subsequent data is available, processing continues to block  403 . If data is available, two paths are taken in parallel to Signature Detected  410  and to Requires Serial Data Output  406 . If a signature is detected at block  410 , a binary signal is set to indicate a positive detection binary signal at block  415 . In parallel, Characteristic Serial Data Signal  414  is made available to the rest of the system. If detailed data is available at block  411 , a detailed serial data available binary signal is set at block  416 . If the stage at block  406  requires serial data to be output, the program flows to block  407 . If there is no such requirement, the program flows to block  403 . At block  407 , if Fast Fourier Transformed data (FFT) is required, the program flows to block  412 ; otherwise, the program flow continues to block  403 . FFT processing for the serial data display  412  formats and calculates the necessary data points to be passed to block  417  for subsequent display of that data to the user. 
         [0023]      FIG. 5  shows a viscosity sensor  106  and a velocity sensor  105  in their physical proximity to an oil flow path  112  within the sensor element  100 .  FIG. 6  shows the detailed mechanical specifications for the two sensors according to the embodiment shown in  FIG. 5 .  FIG. 5  shows the moving parts of the sensors  105  and  106  within their machined fixture. The exploded view shows an unpopulated machined fixture  502 . The velocity and viscosity sensors  105  and  106  are substantially similar; the only difference between the two sensors  105  and  106  is the shape of the rotor that is exposed to the flowing lubricant. In the case of the viscosity sensor  106 , the shape of the rotor  503  is of a substantially smooth design as shown in  FIG. 6 . For the velocity sensor  105 , the rotor  504  has a shape like that of a paddle wheel. Each of sensors  105  and  106  comprises a wheel  508  with an imbedded magnet that is coupled via a cylindrical shaft  506  to the rotor. The sensors  105  and  106  are mounted within a mechanical recess  502  in such a manner so as to allow the viscosity and velocity rotors  503  and  504  to rotate in a manner substantially related to the flow of the fluid within path  112 . The coupled assembly (sensors  105  and  106 ) is shown at  507  in  FIG. 6 . A metallic bushing  509  surrounds shaft  506  in such a manner so as to allow shaft  506  to freely rotate. Such rotation causes the magnet wheel  508  to move in alternating proximity to viscosity Hall sensor element  505  or velocity Hall sensor element  605  and thereby generate the related electrical signals that are eventually coupled via wire elements  122  to the electronic components of the overall system. According to one embodiment of the invention, the only allowed difference between the viscosity sensor and the velocity sensor is the shape of the fluid-submerged rotors (or wheels). The viscosity wheel  503  must be substantially smooth (i.e., no teeth-like protrusions) in comparison to the velocity geared wheel  504 . 
         [0024]      FIG. 7  illustrates the relations between the input and outputs of the Hall-based fluid velocity sensor  105  and the Hall-based fluid viscosity sensor  106 . Block diagram  701  represents the process flow from the rotation of the sensor rotor or wheel to the finalized digital signal representing that rotation. Graphs  702  represent the idealized sinusoidal electrical signals associated with the elements of block diagram  701 . The graph  703  represents the idealized relation between the output signals of the Hall-based velocity sensor  105  and those of the Hall-based viscosity sensor  106 . The equation  704  generally represents the relationship between the velocity and viscosity data components. According to one embodiment, V=Fv−Fs. ‘V’ (calculated viscosity) is then inversely related to the fluidic viscosity with consideration for factors affecting fluidic velocity, temperature, and pressure. For this equation to be effective in relating the appropriate data, Fv must be greater than or equal to Fs. Fv is defined as the frequency of the gear-shaped sensor element. Fs is defined as the frequency of the non-standard-shaped sensor element. F is directly related to the rotational rate of the rotating sensor wheel and is defined as 1/T. T is the pulse duration in seconds of the output of the sensor elements as depicted at  702 . 
         [0025]    The foregoing description, for purposes of explanation, has been described with reference to exemplary embodiments. The illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The exemplary embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.