The present disclosure relates to control of intake air flow used for combustion in an internal combustion engine, and more particularly to a system and method for controlling intake air flow used for combustion in an internal combustion engine using variable valve actuation on an internal combustion engine having in-cylinder pressure sensors.
Many factors, including environmental responsibility efforts and modern environmental regulations on engine exhaust emissions, have reduced the allowable acceptable levels of certain pollutants that enter the atmosphere following the combustion of fossil fuels. Increasingly, more stringent emission standards may require greater control over either or both the combustion of fuel and post combustion treatment of the exhaust. For example, the allowable levels of nitrogen oxides (NOx) and particulate matter have been greatly reduced over the last several years. Fuel injection timing and a quantity of fuel to be injected has been found to be an important factor in emission formation, along with other aspects such as exhaust gas recirculation (EGR), vane settings of variable geometry turbochargers (VGTs), intake manifold temperature, and intake valve timing.
One approach to control fuel injection timing has utilized an in-cylinder pressure sensor in order to more accurately control the crank angle where a certain percentage of fuel injected into the cylinder had combusted, such that the crank angle past top dead center (TDC) where 50% of the fuel injected into a cylinder had combusted was generally identical between cylinders in an engine having a plurality of cylinders. Similarly, phasing of the fuel injection into each cylinder may be monitored and controlled such that the crank angle at start of fuel injection into any one cylinder does not differ beyond a threshold amount from an average crank angle for start of fuel injection. Precise control of fuel injection can be utilized to regulate combustion in a manner that reduces engine emissions and improves fuel consumption. However, while controlling fuel injection is useful from an emissions and fuel consumption perspective, control of intake air flow into cylinders of an engine is also important in controlling engine emissions and fuel consumption.
Variable valve actuation is known to be used to control an amount of intake air, typically a mixture of intake air and recirculated engine exhaust, used for combustion. Differences in an amount of intake air fed to each cylinder may result in cylinder-to-cylinder differences in torque output, higher emissions, and increased fuel consumption. Previous attempts to utilize variable valve actuation have not been able to precisely control air flow into each cylinder. Therefore, a need exists for a method and system to control a variable valve actuation system to balance air flow into each cylinder of an internal combustion engine.
According to one process, a method of controlling a variable valve actuation system for an internal combustion engine having a plurality of cylinders, each of the plurality of cylinders has a variable valve actuator and in-cylinder pressure sensor is provided. Output of an in-cylinder pressure sensor, wherein the in-cylinder pressure sensor is in operable communication with one of a plurality of cylinders, is monitored at a predetermined crank angle Θp with an electronic control module. The output of the in-cylinder pressure sensor of the monitored one of the plurality of cylinders at the predetermined crank angle Θp is compared to a stored threshold value for in-cylinder pressure at the predetermined crank angle. A variable valve actuator is adjusted to adjust a crank angle Θc corresponding to when an intake valve of the monitored one of the plurality of cylinders closes when the output of the in-cylinder pressure sensor of the monitored one of the plurality of cylinders does not correspond to the stored threshold value.
According to another process, a method of controlling a variable valve actuation system for an internal combustion engine having a plurality of cylinders, each of the plurality of cylinders has a variable valve actuator and in-cylinder pressure sensor, is provided. Output of an in-cylinder pressure sensor of a plurality of cylinders at a predetermined crank angle Θp is monitored with an electronic control module. A pressure setpoint value of the plurality of cylinders at a predetermined crank angle Θp is generated. The output of each of the plurality of in-cylinder pressure sensors at the predetermined crank angle Θp is compared to the pressure setpoint value. A revised valve closing crank angle Θc is generated for each of the plurality of cylinders. A variable valve actuator is adjusted to adjust the valve closing crank angle Θc for each of the plurality of cylinders to the revised valve closing crank angle Θc.
According to one embodiment, a physical computer program product, comprises a computer usable medium that has an executable computer readable program code embodied therein. The executable computer readable program code implements a method of controlling a variable valve actuation system for an internal combustion engine has a plurality of cylinders, each of the plurality of cylinders having a variable valve actuator and in-cylinder pressure sensor is provided. Output of an in-cylinder pressure sensor, wherein the in-cylinder pressure sensor is in operable communication with one of a plurality of cylinders, is monitored at a predetermined crank angle Θp with an electronic control module. The output of the in-cylinder pressure sensor of the monitored one of the plurality of cylinders at the predetermined crank angle Θp is compared to a stored threshold value for in-cylinder pressure at the predetermined crank angle. A variable valve actuator is adjusted to adjust a crank angle Θc corresponding to when an intake valve of the monitored one of the plurality of cylinders closes when the output of the in-cylinder pressure sensor of the monitored one of the plurality of cylinders does not correspond to the stored threshold value.
a and 5b are graphs showing the affect of using the variable valve actuation system of the present disclosure on cylinder pressure and heat release.
The engine 10 additionally has an air intake system 22. The air intake system 22 has a first turbocharger compressor 24 and a second turbocharger compressor 26. A charge air cooler 28 is additionally provided to cool intake air within the air intake system 22. A first throttle valve 30 and a second throttle valve 32 are also disposed within the air intake system 22. The first turbocharger turbine 18 and the first turbocharger compressor 24 form a first turbocharger and the second turbocharger turbine 20 and the second turbocharger compressor 26 form a second turbocharger. It is contemplated that the first turbocharger and the second turbocharger may be variable geometry turbochargers.
Turning now to
Turning now to
The processor 70 generates an adjustment for a variable valve actuator that adjusts a crank angle when an intake valve for a cylinder will close. For example, if the comparator 62 shows that the actual in-cylinder pressure within a particular cylinder is lower than the threshold value, the variable valve actuator will be controlled to close the valve earlier, i.e., at a crank angle that is a greater number of degrees before TDC than the previous crank angle when the intake valve closed. Conversely, if the comparator 62 shows that the actual in-cylinder pressure within a particular cylinder is higher than the threshold value, the variable valve actuator will be controlled to close the valve later, i.e., at a crank angle that is a lesser number of degrees before TDC than the previous crank angle when the intake valve closed.
A summation unit 72 receives the adjustment value for the variable valve actuator from the processor 70, and also receives the previous variable valve actuator setting 74. The summation unit adjusts the previous variable valve actuator setting 74 by the adjustment value, and transmits an adjusted variable valve actuator setting to the engine 68.
Utilizing the in-cylinder pressure based control of the variable valve actuators for each of the cylinders of the engine, volumetric inefficiencies from cylinder-to-cylinder in an engine having a plurality of cylinder may be reduced. The reduction of these volumetric inefficiencies also reduces imbalances of heat transfer, piston-ring leakage, and uneven compression within cylinders.
a shows a graph of in-cylinder pressures for an engine with eight cylinders as well as a heat release graph for the engine with eight cylinders. The engine of
b shows a similar graph as shown in
Turning now to
Similarly,
In addition to reducing emissions output and fuel consumption, an engine with in-cylinder pressure sensor controlled variable valve actuators also achieve greater stability in start of fuel injection for the plurality of cylinders.
It will be understood that a control system may be implemented in hardware to effectuate the method. The control system can be implemented with any or a combination of the following technologies, which are each well known in the art: a discrete logic circuit(s) having logic gates for implementing logic functions upon data signals, an application specific integrated circuit (ASIC) having appropriate combinational logic gates, a programmable gate array(s) (PGA), a field programmable gate array (FPGA), etc.
When the control system is implemented in software, it should be noted that the control system can be stored on any computer readable medium for use by or in connection with any computer related system or method. In the context of this document, a “computer-readable medium” can be any medium that can store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer readable medium can be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic) having one or more wires, a portable computer diskette (magnetic), a random access memory (RAM) (electronic), a read-only memory (ROM) (electronic), an erasable programmable read-only memory (EPROM, EEPROM, or Flash memory) (electronic), an optical fiber (optical) and a portable compact disc read-only memory (CDROM) (optical). The control system can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US10/54438 | 10/28/2010 | WO | 00 | 4/29/2013 |