The present invention relates to internal combustion engines and in particular to a system for precise measurement of combustion for engine control.
Modern internal combustion engines provide sophisticated control systems for managing combustion to increase engine efficiency and/or reduce undesired emissions. Such control systems may adjust spark timing, fuel timing and amount, and valve timing to adjust combustion conditions within the engine to a target state under varying loads, fuel grades, and environmental conditions.
The desired target state for optimal combustion is unstable and for this reason the control system must constantly monitor the combustion process as it evolves to recompute the control outputs. For this purpose, it is important to have accurate knowledge of combustion temperature and other features of the combustion gas within the combustion chamber. Such information is difficult to obtain. Experimental internal combustion engines for research may provide windows into the combustion chamber that allow direct monitoring of the combustion process; however, windows are subject to fouling by soot and the like and require regular cleaning. This requirement for regular cleaning makes such combustion chamber windows largely impractical for commercial engines.
The present invention places combustion chamber windows in the cylinder wall at locations where they may be wiped by the piston rings of the piston to remove obscuring particulate matter. Because windows placed in this position are inevitably coated with contaminated oil distributed over the cylinder walls by the piston rings, the cylinder walls would appear to be a poor candidate for window location. The inventors, however, have determined that a controlled thin layer of contaminated oil permits sufficient transmission for absorption spectrometry. The result is a system that can provide real-time combustion gas analysis suitable for long-term use in commercial engines.
Specifically then, the present invention provides an internal combustion engine having a combustion chamber providing a cylindrical passageway terminating at a cylinder head. A piston is sized to slidably reciprocate within the cylindrical passageway and includes at least one piston ring encircling the piston and elastically biased outward to engage inner walls of the cylindrical passageway with movement of the piston. The combustion chamber includes at least one window on the inner wall of the cylindrical passageway providing a passage of light into and out of the combustion chamber through the inner wall, an inner surface of the window positioned proximate to the inner surface to be cleared of optically obscuring contamination by movement of the piston ring thereacross with reciprocation of the piston.
It is thus a feature of at least one embodiment of the invention to provide a window into the combustion chamber, for optical measurements of combustion gases, so that the window is resistant to long-term fouling and thus suitable for standard commercial engines.
The internal combustion engine may further include a lubrication system delivering oil through openings in the piston to be distributed over the inner wall of the cylindrical passageway and the window with movement of the piston.
It is thus a feature of at least one embodiment of the invention to use an oil layer to protect the window against initial adhesion of damaging fouling deposits.
The window may be offset inward from the inner wall of the cylindrical chamber.
It is thus a feature of at least one embodiment of the invention to preserve a protective layer of oil during initial engine operation and to accommodate cylinder wear. The inventor has determined that a thin layer of dirty oil can be accommodated by the optical measurements thus permitting a longer-lived system.
The window may be offset inward by less than 150 micrometers and in some embodiments by less than 50 micrometers.
It is thus a feature of at least one embodiment of the invention to position the window close enough to the piston rings so that the piston rings remove fouling deposits leaving only a thin layer of oil.
The internal combustion engine may include at least one of an electronic light sensor and electronic light emitter positioned outside of the combustion chamber to receive light through the at least one window. The engine may include an optical spectroscope communicating with at least one of the electronic light sensor and electronically emitter to provide a measure of the optical absorption by gases within the combustion chamber.
It is thus a feature of at least one embodiment of the invention to permit spectrographic analysis of combustion gases such as can yield a variety of measurements including gas temperature.
The optical spectroscope may measure absorption of water vapor within a temperature range of a combustion engine.
It is thus a feature of at least one embodiment of the invention to permit the measurement of water vapor as a proxy for combustion temperature.
The engine may include a controller for receiving a temperature measurement from the optical spectroscope to control the fuel delivery system according to a stored program optimizing operation of the internal combustion engine for at least one of fuel efficiency, power, and reduced emissions.
It is thus a feature of at least one embodiment of the invention to provide more precise engine control possible by direct measurement of combustion gases.
The window may have a diameter of less than three millimeters.
It is thus a feature of at least one embodiment of the invention to provide a ready integration into the combustion cylinder wall with minimal structural effect and required pressure resistance.
The window may have a surface facing inward to the combustion chamber that is a sector of the cylinder aligned with and conforming to a cylinder defining the cylindrical passageway.
It is thus a feature of at least one embodiment of the invention to provide a window optimized for a broad area clearance by passing piston rings.
The internal combustion engine may include a window constructed of a material selected from the group consisting of silica and sapphire.
It is thus a feature of at least one embodiment of the invention to provide long life window materials resistant to frictional abrasion.
The piston may provide a piston pin extending along an axis to provide a pivoting joint with a connecting rod communicating between the piston and a crankshaft, and the window may be positioned on the inner wall of the cylindrical passageway within 45 degrees of a vertical plane of the axis of the piston pin as measured about an axis of symmetry of the cylindrical passageway. In addition, or alternatively, the window may be positioned above the bottom dead center location and below a midpoint between the top dead center and bottom dead center positions.
It is thus a feature of at least one embodiment of the invention to position the window at a region of minimized cylinder wear to maximize window life.
These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention.
Referring now to
The cylinder head 16 may provide for valve openings 18 and 20 having corresponding valves 22 and 24. Valve 22 may control the exit of exhaust gases from the combustion chamber 12 through an exhaust manifold 26. Valve 24 may control the receipt of air and fuel to an intake manifold 28, the latter including a fuel injector 30 of conventional design. Alternatively, it will be appreciated that the fuel injector 30 may be placed directly in the cylinder head 16 to inject fuel directly into the combustion chamber 12.
For gasoline engines, the cylinder head 16 may support a spark plug 32 having electrodes exposed within the combustion chamber 12; however, the present invention is equally applicable to diesel engines where the spark plug 32 is not required.
A piston 34, having a generally cylindrical shape, fits within the cylindrical passageway 14 to slide closely therein in a reciprocating motion as indicated by arrow 36. This reciprocating motion moves the piston 34 between bottom dead center 38 and top dead center 40 positions. An upper edge of the piston 34 includes a ring pack 42 being a set of circular metal rings radially compressed to fit in corresponding slots of the piston 34 opening radially outward from the cylindrical piston wall. The rings of the ring pack 42 expand outward to form a tight seal between the piston 34 and the inner wall of the cylindrical passageway 14.
The piston 34 may provide a wrist pin 46 attaching the piston 34 to a connecting rod, 44 the latter attached to a crankshaft (not shown). The wrist pin 46 allows the piston 34 to pivot with respect to the connecting rod 44 along a pivot axis 48 accommodating the eccentric movement of a crankshaft attachment while allowing the piston 34 to move in a substantially straight line up and down.
Referring now also to
Referring again to
Ideally, the optical ports 62 are placed beneath a midpoint between bottom dead center 38 and top dead center 40 such as represent regions of reduced cylinder wear and fouling. Further, the optical ports 62 may be placed generally in a vertical plane aligned with axis 48 representing a location of the cylinder wall having reduced scuffing as a result of the limited rotational freedom of the piston 34 in that plane. Ideally the optical ports 62 are within 45 degrees of this plane measured about an axis of symmetry of the cylindrical passageway 14.
Referring still to
The spectroscope 66 may provide, for example, a swept frequency light source using optical assembly 64 whose intensity is measured by a broadband light sensor or may provide a broadband light source with a frequency discriminating sensor or other frequency discriminating mechanism. The invention contemplates other possible spectroscope designs including but not limited to those with optical gratings and filters and the like.
The spectroscope 66 may communicate with an engine controller 70, for example, having a processor 72 and executing a program stored in electronic memory 74 to control the combustion engine 10. In particular, the engine controller 70 may control: the spark plug 32 timing, timing of the valves 24 and 22 (by a cam mechanism not shown), timing of the fuel injector 30, and amount of fuel injected by the fuel injectors 30 during each cycle. Generally, the engine controller will operate using an engine model map 78 defining combinations of these control parameters that will optimize the engine operating state with respect to an objective function of fuel efficiency, power, or emissions as is generally understood in the art.
Referring now to
The inner surface of the light transmissive window 65 may be flush with the inner wall surface 56 of the cylindrical passageway 14 or may be recessed by a recess amount 67 of less than 200 microns and typically less than 150 microns and in some cases less than 50 microns. This recess amount 67 allows cylinder wear (typically as much is 0.5 millimeters) increasing the diameter of the cylindrical passageway 14 with reduced risk that the light transmissive window 65 will protrude from the eroded inner wall surface 56 and be damaged. This recess amount 67 also promotes a protective layer of oil 71 covering the window 65 during initial use such as helps prevent the adhesion of light obscuring particles 73 including partially combusted fuel soot and the like. Motion of the piston ring pack 42 across the window surface dislodges these light-blocking particles and refreshes the oil layer.
The present inventor has determined that current spectroscopy systems can operate through a thin layer of dirty oil 71 holding some light-blocking particles. Such oil 71 will producing an attenuation of less than 20 decibels per window 65 resulting in a total line of sight transmission of at least 100 parts per million sufficient for gas phase absorption spectroscopy.
For a single window system, shown in
In an alternative design, as shown in
Referring to
Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context.
When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
References to “a controller” and “a processor” or “spectroscope” and “the processor,” can be understood to include one or more processors or devices that can communicate in a stand-alone and/or a distributed environment(s), and can thus be configured to communicate via wired or wireless communications with other processors, where such one or more processor can be configured to operate on one or more processor-controlled devices that can be similar or different devices. Furthermore, references to memory, unless otherwise specified, can include one or more processor-readable and accessible memory elements and/or components that can be internal to the processor-controlled device, external to the processor-controlled device, and can be accessed via a wired or wireless network.
It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications, are hereby incorporated herein by reference in their entireties.
This application claims the benefit of U.S. provisional 62/681,485 filed Jun. 6, 2018, which is hereby incorporated by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/US2019/034861 | 5/31/2019 | WO | 00 |
Number | Date | Country | |
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62681485 | Jun 2018 | US |