Patent Application
20110087422
The present disclosure relates to systems and methods for supplying power for fuel injection and for ionization current sensing in internal combustion engines.
Various types of spark-ignition, compression-ignition, and combination internal combustion engines use direct injection of fuel into the combustion chamber to reduce fuel consumption and feedgas emissions. These may include direct-injection spark-ignition (DISI) engines fueled by gasoline or gasoline/alcohol mixtures, compression-ignition engines fueled by diesel fuel, or combination engines fueled by gasoline or other fuels that may operate in a spark-ignition mode and a compression-ignition mode, sometimes referred to as homogeneous charge compression ignition (HCCI) mode, for example. A high-voltage power supply may be provided to generate the current required for desired performance of the fuel injectors for these applications, with representative voltages in the range of 60V or more compared to the nominal battery voltage of 12V or 24V, for example.
Manufacturers continue to improve control of internal combustion engines to enhance fuel economy and performance while reducing feedgas emissions using more sophisticated sensing and processing hardware and software. To improve control of the combustion process, ionization current sensing (or ion sense) uses a bias voltage applied across a sensor positioned within the combustion chamber to generate a current signal indicative of the combustion quality and timing. The bias voltage for reliable ion current signals often exceeds the voltage available directly from the vehicle battery so that a boost circuit or high voltage power supply is used to provide a bias voltage in the range of 85V or more, for example. Some spark-ignition engines provide the high-voltage supply by switching the ignition coil or using the ignition coil to charge a capacitor during the spark generation and then discharge the capacitor to provide the bias voltage during the ion sense period. While suitable for some applications, these systems do not provide a bias voltage for ion sense when no spark is generated, such as during compression-ignition mode in HCCI engines, for example.
An electrical power system for an engine powered at least in part by a battery having a battery voltage and including a fuel injector and at least one ionization sensor includes at least one common power supply connected to the fuel injector and the ionization sensor and supplying a voltage higher than the battery voltage for operation of the fuel injector and the ionization sensor at least during an ionization sensing period after spark discharge.
In one embodiment a direct injection multiple cylinder internal combustion engine includes an electrical system powered at least in part by a battery having an associated battery voltage, a fuel injector associated with each cylinder and configured to inject fuel directly into the combustion chamber of an associated cylinder in response to control signals during operation of the engine, at least one ionization sensor positioned within one of the cylinders, and at least one high-voltage power supply connected to at least one fuel injector and at least one ionization sensor for supplying a voltage higher than the battery voltage for operation of the fuel injector and the ionization sensor. Embodiments include ionization current sensors implemented by dedicated sensors, or by combination devices, such as a spark plug or glow plug, for example.
The present disclosure includes embodiments having various advantages. For example, the systems and methods of the present disclosure can provide ionization current sensing whether or not a spark plug discharge is provided, such as in compression ignition engines or operating modes, which include diesel engines and HCCI engines, for example. Using the high-voltage supply in spark-ignited applications for ignition coil charging facilitates more agile ignition timing with shorter ignition coil charge times and shorter dwell times, which in turn provides a larger time period for collecting ionization current data that is typically masked during coil/spark discharge. Using a single high-voltage power supply to actuate injectors and ionization sensing may provide a cost savings and reduce the number of control module pins required when the power supply is integrated within the engine controller.
The above advantages and other advantages and features will be readily apparent from the following detailed description of the preferred embodiments when taken in connection with the accompanying drawings.
As those of ordinary skill in the art will understand, various features of the embodiments illustrated and described with reference to any one of the Figures may be combined with features illustrated in one or more other Figures to produce alternative embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations. The representative embodiments used in the illustrations relate generally to a, multi-cylinder, internal combustion engine with direct or in-cylinder injection and an ion sensing system that uses a spark plug, glow plug, or dedicated ionization sensor disposed within the cylinders. Those of ordinary skill in the art may recognize similar applications or implementations with other engine/vehicle technologies.
System 10 includes an internal combustion engine having a plurality of cylinders, represented by cylinder 12, with corresponding combustion chambers 14. As one of ordinary skill in the art will appreciate, system 10 includes various sensors and actuators to effect control of the engine. A single sensor or actuator may be provided for the engine, or one or more sensors or actuators may be provided for each cylinder 12, with a representative actuator or sensor illustrated and described. For example, each cylinder 12 may include four actuators that operate intake valves 16 and exhaust valves 18 for each cylinder in a multiple cylinder engine. However, the engine may include only a single engine coolant temperature sensor 20.
Controller 22 has a microprocessor 24, which is part of a central processing unit (CPU), in communication with memory management unit (MMU) 25. MMU 25 controls the movement of data among various computer readable storage media and communicates data to and from CPU 24. The computer readable storage media preferably include volatile and nonvolatile storage in read-only memory (ROM) 26, random-access memory (RAM) 28, and keep-alive memory (KAM) 30, for example. KAM 30 may be used to store various operating variables while CPU 24 is powered down. The computer-readable storage media may be implemented using any of a number of known memory devices such as PROMs (programmable read-only memory), EPROMs (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or any other electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions, used by CPU 24 in controlling the engine or vehicle into which the engine is mounted. The computer-readable storage media may also include floppy disks, CD-ROMs, hard disks, and the like.
System 10 includes an electrical system powered at least in part by a battery 116 providing a nominal voltage, VBAT, which is typically either 12V or 24V, to power controller 22. As will be appreciated by those of ordinary skill in the art, the nominal voltage is an average design voltage with the actual steady-state and transient voltage provided by the battery varying in response to various ambient and operating conditions that may include the age, temperature, state of charge, and load on the battery, for example. Power for various engine/vehicle accessories may be supplemented by an alternator/generator during engine operation as well known in the art. A high-voltage power supply 120 generates a boosted nominal voltage, VBOOST, relative to the nominal battery voltage and may be in the range of 85V-100V, for example, depending upon the particular application and implementation. Power supply 120 is used to power fuel injectors 80 and an ionization sensor, such as spark plug 86. As illustrated in the embodiment of
CPU 24 communicates with various sensors and actuators via an input/output (I/O) interface 32. Interface 32 may be implemented as a single integrated interface that provides various raw data or signal conditioning, processing, and/or conversion, short-circuit protection, and the like. Alternatively, one or more dedicated hardware or firmware chips may be used to condition and process particular signals before being supplied to CPU 24. Examples of items that are actuated under control by CPU 24, through I/O interface 32, are fuel injection timing, fuel injection rate, fuel injection duration, throttle valve position, spark plug ignition timing (in the event that engine 10 is a spark-ignition engine), ionization current sensing and conditioning, and others. Sensors communicating input through I/O interface 32 may indicate piston position, engine rotational speed, vehicle speed, coolant temperature, intake manifold pressure, accelerator pedal position, throttle valve position, air temperature, exhaust temperature, exhaust air to fuel ratio, exhaust constituent concentration, and air flow, for example. Some controller architectures do not contain an MMU 25. If no MMU 25 is employed, CPU 24 manages data and connects directly to ROM 26, RAM 28, and KAM 30. Of course, the present invention could utilize more than one CPU 24 to provide engine control and controller 22 may contain multiple ROM 26, RAM 28, and KAM 30 coupled to MMU 25 or CPU 24 depending upon the particular application.
In operation, air passes through intake 34 and is distributed to the plurality of cylinders via an intake manifold, indicated generally by reference numeral 36. System 10 preferably includes a mass airflow sensor 38 that provides a corresponding signal (MAF) to controller 22 indicative of the mass airflow. A throttle valve 40 may be used to modulate the airflow through intake 34. Throttle valve 40 is preferably electronically controlled by an appropriate actuator 42 based on a corresponding throttle position signal generated by controller 22. The throttle position signal may be generated in response to a corresponding engine output or demanded torque indicated by an operator via accelerator pedal 46. A throttle position sensor 48 provides a feedback signal (TP) to controller 22 indicative of the actual position of throttle valve 40 to implement closed loop control of throttle valve 40.
A manifold absolute pressure sensor 50 is used to provide a signal (MAP) indicative of the manifold pressure to controller 22. Air passing through intake manifold 36 enters combustion chamber 14 through appropriate control of one or more intake valves 16. Intake valves 16 and exhaust valves 18 may be controlled using a conventional camshaft arrangement, indicated generally by reference numeral 52. Camshaft arrangement 52 includes a camshaft 54 that completes one revolution per combustion or engine cycle, which requires two revolutions of crankshaft 56 for a four-stroke engine, such that camshaft 54 rotates at half the speed of crankshaft 56. Rotation of camshaft 54 (or controller 22 in a variable cam timing or camless engine application) controls one or more exhaust valves 18 to exhaust the combusted air/fuel mixture through an exhaust manifold. A cylinder identification sensor 58 provides a signal (CID) once each revolution of the camshaft or equivalently once each combustion cycle from which the rotational position of the camshaft can be determined. Cylinder identification sensor 58 includes a sensor wheel 60 that rotates with camshaft 54 and includes a single protrusion or tooth whose rotation is detected by a Hall effect or variable reluctance sensor 62. Cylinder identification sensor 58 may be used to identify with certainty the position of a designated piston 64 within cylinder 12 for use in determining fueling or ignition timing, for example.
Additional rotational position information for controlling the engine is provided by a crankshaft position sensor 66 that includes a toothed wheel 68 and an associated sensor 70. In one embodiment, toothed wheel 68 includes thirty-five teeth equally spaced at ten-degree (10°) intervals with a single twenty-degree gap or space referred to as a missing tooth. In combination with cylinder identification sensor 58, the missing tooth of crankshaft position sensor 66 may be used to generate a signal (PIP) used by controller 22 for fuel injection and ignition timing. A dedicated integrated circuit chip (EDIS) within controller 22 may be used to condition/process the raw rotational position signal generated by position sensor 66 and outputs a signal (PIP) once per cylinder per combustion cycle. Crankshaft position sensor 66 may also be used to determine engine rotational speed and to identify cylinder combustion events based on an absolute, relative, or differential engine rotation speed where desired.
An exhaust gas oxygen sensor 62 provides a signal (EGO) to controller 22 indicative of whether the exhaust gasses are lean or rich of stoichiometry. Depending upon the particular application, sensor 62 may provide a two-state signal corresponding to a rich or lean condition, or alternatively a signal that is proportional to the stoichiometry of the exhaust feedgas. This signal may be used to adjust the air/fuel ratio, or control the operating mode of one or more cylinders, for example. The exhaust gas is passed through the exhaust manifold and one or more emission control or treatment devices 90 before being exhausted to atmosphere.
A fuel delivery system includes a fuel tank 100 with a fuel pump 110 for supplying fuel to a common fuel rail 112 that supplies injectors 80 with pressurized fuel. In some direct-injection applications, a camshaft-driven high-pressure fuel pump (not shown) may be used in combination with a low-pressure fuel pump 110 to provide a desired fuel pressure within fuel rail 112. Fuel pressure may be controlled within a predetermined operating range by a corresponding signal from controller 22. In the representative embodiment illustrated in
Driver 82 may include various circuitry and/or electronics to selectively supply power from high-voltage power supply 120 to actuate a solenoid associated with fuel injector 80 as described in greater detail with reference to
In the embodiment of
In one embodiment, each spark plug 86 includes a dedicated coil and associated electronics. Alternatively, a single ignition system 84 may be associated with multiple spark plugs 86. In addition, ignition system 84 may include various components to provide ionization current sensing as describe with reference to
Controller 22 includes software and/or hardware implementing control logic to control system 10. In one embodiment, controller 22 controls high-voltage power supply 120, fuel injector 80, and spark plug 86 such that power supply 120 selectively provides substantially the same boosted nominal voltage (relative to battery voltage) to fuel injector 80 via driver 82 and to spark plug 86 via ignition system 84. Of course, the actual voltages may vary as a function of ambient and operating conditions. Similarly, different boosted nominal voltage may be supplied to the fuel injectors 80 and spark plugs 86 or other ionization current sensors depending upon the particular application and implementation.
In operation, switch 210 and switch 214 are closed to selectively connect fuel injector solenoid 82 to the high-voltage supply, VBOOST. Current is blocked by diodes 220 and 222 and flows through solenoid coil 82 to initiate a fuel injection event. A holding current may subsequently be applied using battery voltage and appropriate actuation of switches 210, 212, and 214 to complete the fuel injection event. Substantially the same voltage from the high-voltage supply 120 may be used to charge ignition coil 84 to generate a spark across the air gap of spark plug 86, and subsequently to apply a bias voltage to induce an ionization current signal, Isense, indicative of combustion quality and timing within the corresponding cylinder. To charge ignition coil 84, switch 216 is closed connecting one side 244 of primary winding 240 to ground with the other side 242 of primary winding 240 connected to the boost voltage causing current to flow through primary winding 240. Soft turn-on technology may be used to ensure that the spark discharge event does not occur at the initiation of coil charging rather than the at the desired coil turn-off time. When the control logic of controller 22 generates a spark signal, switch 216 is opened to collapse the magnetic field of coil 84 and induce a high voltage (on the order of kilovolts) in secondary winding 250 resulting in a spark discharge across the electrodes of spark plug 86 to initiate combustion within the corresponding cylinder. The boost voltage is then used as a bias voltage across spark plug 86 with ions generated during combustion of the fuel/air mixture within the cylinder conducting across the air gap of spark plug 86 and generating a small ionization current 230 detected by controller 22. A current minor or similar circuitry may be integrated into ignition system 84 or controller 22 to detect and amplify the ionization current signal.
As illustrated in the embodiment of
As such, the present disclosure includes embodiments that provide a shared high-voltage power supply for ionization current sensors and fuel injectors that facilitates ionization current sensing whether or not a spark plug discharge is provided, such as in compression ignition engines or operating modes including diesel engines and HCCI engines, for example. The availability of a high-voltage power supply in spark-ignited applications for use in charging the ignition coil facilitates more agile ignition timing with shorter ignition coil charge times and shorter dwell times, which in turn provides a larger time period for collecting ionization current data, which is typically masked during coil/spark discharge. Using a single high-voltage power supply to actuate injectors and ionization sensing according to the present disclosure may also provide a cost savings and reduce the number of control module pins required when the power supply is integrated in the engine controller.
While the best mode has been described in detail, those familiar with the art will recognize various alternative designs and embodiments within the scope of the following claims. While various embodiments may have been described as providing advantages or being preferred over other embodiments with respect to one or more desired characteristics, as one skilled in the art is aware, one or more characteristics may be compromised to achieve desired system attributes, which depend on the specific application and implementation. These attributes include, but are not limited to: cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. The embodiments discussed herein that are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
This application is a division of U.S. application Ser. No. 11/876,798 filed Oct. 23, 2007, now U.S. Pat. No. ______, the disclosure of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11876798 | Oct 2007 | US |
| Child | 12973191 | US |
