摘要:
A cam phase control method for an internal combustion engine schedules cam phase to optimize emissions and fuel economy, but bounds the scheduled cam phase for continuous achievement of the desired inlet airflow. The volumetric efficiency required to achieve the desired inlet airflow at a specified intake manifold vacuum is compared to the maximum achievable volumetric efficiency at the specified vacuum. When the required volumetric efficiency is less than the maximum value, the cam phase is controlled according to the lesser of the scheduled cam phase and the highest cam phase for achieving the required volumetric efficiency; when the required volumetric efficiency is equal to or greater than the maximum value, the cam phase is controlled to a setting that maximizes the volumetric efficiency.
摘要:
A method of estimating the concentration of residual exhaust gas in an internal combustion engine having variable cam phase control is based on engine dynamometer and engine simulator data. Since both the volumetric efficiency and the residual exhaust gas concentration of an engine vary monotonically in response to changes in cam phase, the simulated residual concentration data is deemed to be reliable if the simulated volumetric efficiency data matches volumetric efficiency data determined by engine dynamometer testing. Volumetric efficiency test data is compared to simulated volumetric efficiency data, and the simulation software is tuned until the simulated data matches the test data. At such point, the simulated residual concentration data is deemed to be reliable, and is used to calibrate a model relating residual concentration to cam phase angle, and such model is then used by an engine controller to estimate residual exhaust gas concentration during operation of the engine.
摘要:
A method for determining an estimate of a response characteristic that depends on a number of input factors includes developing a mathematical model of the response as a function of the input factors based on a statistical fit of a plurality of measured data points. The method also includes mapping the value of the response characteristic and the input factors at a plurality of conditions. The method combines the mapped data with the mathematical model to produce an estimate of the response characteristic that is more accurate over a range of conditions than either the mapped data or the model taken individually.
摘要:
A standard cam phasing OCV may be employed as a virtual check valve to choke the backflow of oil during negative cam torque conditions, including execution of a duty cycle command in an event-based manner. Normally, OCV duty cycle commands are made on a time basis, but for VCV the duty cycle output change must be synchronized with engine events. A method is disclosed for calculating and delivering the VCV duty cycle so that both time-based and event-based controls are maintained and work together. Phase alignment of response time of the OCV solenoid is based upon cam target wheel edges and is event-based. An initial phase rate vs. phase angle is monitored by the Engine Control Module (ECM). Adjustment of the phase angle is provided to achieve maximum cam position phase rate.
摘要:
A camshaft phaser control system including a camshaft target wheel, the target wheel having first and second teeth for measuring camshaft oscillatory instability. The trailing edge of the first tooth coincides with the negative camshaft oscillation peak, and the trailing edge of the second tooth coincides with the positive camshaft oscillation peak. During each camshaft rotation, each tooth initiates an input signal to generate first and second input signals in known fashion. During crankshaft rotation, a third input signal is generated corresponding to the rotational position of the crankshaft. From these signals, operational camshaft oscillatory instability is computed by an engine monitoring system (EMS). Any deviation from the operational instability while the engine is operating is a direct measurement of oscillatory instability of the camshaft about its nominal holding position. A change in oscillatory instability is inferred as system malfunction, permitting defensive action to be taken by the EMS.
摘要:
A camshaft phaser control system for reducing rotor positional instability. A phaser system includes a target wheel mounted on the phaser rotor such that during camshaft rotation wheel teeth chop a signal to generate first and second interruption signals indicative of amplitude of rotor instability. An instability monitor is used to monitor the level of instability against predetermined acceptable levels, depending upon engine operating conditions (RPM, temperature). An excessive level of instability is established by engine calibration. When measured instability exceeds a predetermined threshold level for a predetermined period, an instability diagnostic becomes alarmed. A default strategy is used to correct the excessive instability by applying a bias to the phaser control duty cycle. The system continues to monitor the level of instability, and when instability falls below the threshold limit, normal phasing operation is resumed.
摘要:
The present invention provides a method and apparatus to control the rate of change of the variable cam phasing system during transient engine operating conditions. It does this primarily to maintain combustion stability. The invention controls the rate of change of the variable cam phasing system based upon the operating point of the engine, the desired operating point of the engine, and the rate of change of the variable cam phasing system necessary to maintain combustion stability.
摘要:
An internal combustion engine having valve deactivation capability for at least one cylinder, or for an entire bank of cylinders in a multiple-bank engine, is provided with a temperature probe in the exhaust stream of that cylinder or cylinder bank. The temperature probe is connected to an Engine Control Module programmed to determine the rate of temperature change during valve deactivation, to compare the determined value to an acceptable range of rates, and to signal, when the rate exceeds an acceptable range. When the valves of a cylinder are properly deactivated, the temperature in the exhaust pipe decreases slowly. However, when valve deactivation fails, the cylinders pump non-combusted air from the intake manifold into the exhaust manifold, resulting in a relatively rapid decrease in exhaust temperature. This abnormal rate of temperature decrease thus can be used as an indicator of failure of the VVA system.
摘要:
A method of estimating the volumetric efficiency of an internal combustion engine having independent intake and exhaust cam phase variation, compensates a nominal or base estimate of the volumetric efficiency in two successive stages: an intake stage, and an exhaust stage. The intake stage compensates for the effects of intake cam variation, using the base volumetric efficiency estimate as a starting point; and the exhaust stage compensates for the effects of exhaust cam variation, using the output of the intake stage as a starting point. The volumetric efficiency so compensated is then used to accurately compute the mass intake airflow for engine control purposes.
摘要:
A standard cam phasing OCV may be employed as a virtual check valve to choke the backflow of oil during negative cam torque conditions, including execution of a duty cycle command in an event-based manner. Normally, OCV duty cycle commands are made on a time basis, but for VCV the duty cycle output change must be synchronized with engine events. A method is disclosed for calculating and delivering the VCV duty cycle so that both time-based and event-based controls are maintained and work together. Phase alignment of response time of the OCV solenoid is based upon cam target wheel edges and is event-based. An initial phase rate vs. phase angle is monitored by the Engine Control Module (ECM). Adjustment of the phase angle is provided to achieve maximum cam position phase rate.