3770 results about "Air–fuel ratio" patented technology

Improved exhaust gas recirculation system and methods that use one or more of the engine's cylinders as dedicated EGR cylinders. All of the exhaust from the dedicated EGR cylinders is recirculated back to the engine intake. Thus, the EGR rate is constant, but the EGR mass flow may be controlled by adjusting the air-fuel ratio of the dedicated EGR cylinders or by using various variable valve timing techniques.

Various systems and methods are disclosed for carrying out combustion in a fuel-cut operation in some or all of the engine cylinders of a vehicle. Further, various subsystems are considered, such as fuel vapor purging, air-fuel ratio control, engine torque control, catalyst design, and exhaust system design.

Various systems and methods are disclosed for carrying out combustion in a fuel-cut operation in some or all of the engine cylinders of a vehicle. Further, various subsystems are considered, such as fuel vapor purging, air-fuel ratio control, engine torque control, catalyst design, and exhaust system design.

A system and method to control engine valve timing to improve air-fuel control in an engine with valves that may be deactivated. Valves that may be deactivated are controlled in a manner to improve detection of individual cylinder air-fuel ratios.

An emission control system has a catalyst and a sensor responding to a component of exhaust gas. In order to speed warming up the catalyst, the emission control system increases the amount of heat dissipated by exhaust gas. A diagnosis of the emission control system is carried out by determining whether the amount of heat dissipated by exhaust gas is sufficient or insufficient. The amount of heat dissipated by exhaust gas is represented by the length of time to an activated state of the sensor. In the diagnosis, the amount of heat generated by a heater provided in the sensor is taken into consideration. The diagnosis can also be carried out before and after the warming up the catalyst. The heater can also be deactivated. Detection of an abnormality of a secondary air control system can be based on a component of exhaust gas. If the amount of heat dissipated by exhaust gas is found insufficient, additional control can be executed. The amount of heat dissipated by exhaust gas can also be represented by an intake air volume and an air-fuel ratio.

An air-fuel ratio control system for an internal combustion engine estimates an oxygen storage amount of a catalyst based on a record of an oxygen storage amount, and controls an air-fuel ratio based on the estimated oxygen storage amount. The catalyst is divided into multiple sections in a flow direction of an exhaust gas, the oxygen storage amount in a specified section is estimated according to a behavior of an exhaust gas on upstream and downstream sides of the respective specified sections, and the air-fuel ratio is controlled based on the estimated oxygen storage amount in the specified section.

A method for operating an engine having a first injector for injecting a first fuel into a cylinder of the engine and a second injector for injection a second fuel into said cylinder of the engine, the engine further having at least an exhaust gas oxygen sensor, the method comprising of varying an amount of said first fuel injection in response to said sensor under a first operating condition, and varying an amount of said second fuel injection in response to said sensor under a second operating condition.

Improved exhaust gas recirculation system and methods that use one or more of the engine's cylinders as dedicated EGR cylinders. All of the exhaust from the dedicated EGR cylinders is recirculated back to the engine intake. Thus, the EGR rate is constant, but the EGR mass flow may be controlled by adjusting the air-fuel ratio of the dedicated EGR cylinders or by using various variable valve timing techniques.

A method is disclosed for controlling operation of an engine coupled to an exhaust treatment catalyst. Under predetermined conditions, such as after an engine cold start, the method operates an engine with a first group of cylinders having a first ignition timing, and a second group of cylinders having a second ignition timing more retarded than the first group. In addition, the engine control method also provides the following features in combination with the above-described split air / lean mode: idle speed control, sensor diagnostics, air / fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, default operation, and exhaust gas and emission control device temperature control. In addition, the engine control method also can change to combusting all cylinders at substantially the same ignition timing under preselected operating conditions such as fuel vapor purging, manifold vacuum control, and purging of stored oxidants in an emission control device.

A diesel particulate filter (14) which traps particulate matter and a NOx trap catalyst (13) which traps nitrogen oxides are installed in series in an exhaust passage (10) of a diesel engine (1). A controller (21) calculates a particulate matter deposition amount in the diesel particulate filter (14) (S4). The controller (21), when the particulate matter deposition amount exceeds a first predetermined amount (PM2), prevents sharp increase of the particulate matter deposition amount by prohibiting rich spike where the oxygen concentration of the exhaust gas is controlled to a value corresponding to a rich air-fuel ratio in order to regenerate the NOx trap catalyst (13) (S301, S302, S306), and prevents the particulate matter deposition amount of the diesel particulate filter (14) from reaching a limit.

A diesel engine (1) provided with a NOx catalyst (28A) and a diesel particulate filter (28B) performs lean burn operation during normal running, rich burn operation during regeneration of the NOx catalyst (28A), operation under the stoichiometric air-fuel ratio during desulphating of the NOx catalyst (28A), and operation under a slightly lean air-fuel ratio to regenerate the filter after desulphating of the NOx catalyst (28A). When the lean burn operation is applied, a controller (31) first controls the fuel injection amount, and controls an air supply amount based on the fuel injection amount. When rich burn operation is applied, the controller (31) first controls the air supply amount and controls the fuel injection amount based on the air supply amount. Due to this control, the response of the excess air factor control is enhanced while preventing torque fluctuation accompanying the variation of the target excess air factor.

An upstream side catalyst and a downstream side catalyst are disposed in an exhaust passage. A first oxygen sensor is disposed between these two catalysts and a second oxygen sensor is disposed downstream of the downstream side catalyst. The air-fuel ratio is forcibly oscillated and the oxygen storage capacity of the upstream side catalyst is detected. Deterioration of the upstream side catalyst is then detected based on whether this oxygen storage capacity is larger than a predetermined value. The forced oscillation of the air-fuel ratio is performed only when the oxygen storage state of the downstream side catalyst is appropriate.

A gas turbine system includes a compressor protection subsystem; a hibernation mode subsystem; and a control subsystem that controls the compressor subsystem and the hibernation subsystem. At partial loads on the turbine system, the compressor protection subsystem maintains an air flow through a compressor at an airflow coefficient for the partial load above a minimum flow rate coefficient where aeromechanical stresses occur in the compressor. The air fuel ratio in a combustor is maintained where exhaust gas emission components from the turbine are maintained below a predetermined component emission level while operating at partial loads.

A method is disclosed for controlling operation of a engine coupled to an exhaust treatment catalyst. Under predetermined conditions, the method operates an engine with a first group of cylinders combusting a lean air-fuel mixture and a second group of cylinders pumping air only (i.e. without fuel injection.) In addition, the engine control method also provides the following features in combination with the above-described split air / lean mode: auto speed control, sensor diagnostics, air-fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, and default operation. In addition, the engine control method also disables the split air / lean operating mode under preselected operating conditions.

A generic technique for the detection of air-fuel ratio (or torque) imbalances in a 4-cylinder engine equipped with either a production oxygen sensor or a wide-range A / F sensor (or a crankshaft torque sensor) is developed. The method is based on a novel frequency-domain characterization of pattern of imbalances and its geometric decomposition into four basic templates. Once the contribution of each basic template to the overall imbalances is computed, templates of opposite direction are imposed to restore air-fuel ratio (or torque) balance among cylinders. At any desired operating condition, elimination of imbalances is achieved within few engine cycles. The method is applicable to current and future engine technologies with variable valve actuation, fuel injectors and / or individual spark control.

The present invention involves a method for maintaining temperature in an exhaust gas treatment device for an internal combustion engine in a hybrid vehicle. The engine has a crankshaft and at least one cylinder. The hybrid vehicle has a fuel storage device and a fuel supply device. An exhaust gas treatment device is located downstream of the cylinder. The method comprises, in an engine off mode, pumping air to the exhaust gas aftertreatment device controlling the fuel supply device so that fuel is allowed to the exhaust gas aftertreatment device. Air flow to the exhaust gas aftertreatment device can be controlled by a throttle in an inlet duct to the engine and / or the fuel supply device to control the combustion and air-fuel ratio in the exhaust gas treatment device.

A system for a vehicle comprising of an engine including a first cylinder group and a second cylinder group; a linear exhaust gas sensor coupled exclusively to the first cylinder group; a switching exhaust gas sensor coupled exclusively to the second cylinder group; and a controller configured to operate the engine in at least a first mode and a second mode, where in the first mode the first and second cylinder groups combust air and fuel, where in the second mode at least one of the first and second cylinder groups combusts air and injected fuel and the other one of the first and second cylinder groups pumps air without injecting fuel, and where the controller is further configured to estimate torque of the engine in each of the first and second modes of operation based on the air-fuel ratio of the first cylinder group and the air-fuel ratio of the second cylinder group independent of the switching sensor and dependent on the linear sensor.

A gaseous-fueled reciprocating internal combustion engine includes a carburetor having a throttle valve that is controlled by a speed governor. A proportional fuel control valve is disposed intermediate a fuel supply and the carburetor, and is controlled by an air fuel computing device. The computing device generates a control signal to adjust the fuel control valve based on a governor sensed variable indicative of engine speed, sensed engine torque, a governor output signal from the governor indicative of an opening position of the throttle valve wherein 100% corresponds to a wide open throttle position, and 0% corresponds to a closed position, and a lean combustion control map containing predetermined set point values stored in memory. During operation, the control valve is responsive to the control signal generated by the computing device for adjustment of a fuel flow therethrough so as to obtain a ratio of air to fuel provided to the engine that is substantially at a lean misfire limit of the engine, thereby reducing fuel consumption, NOx emissions, and reducing exhaust gas temperatures. Alternatively, the control signal is generated using engine speed alone.

A method for operating and engine having a cylinder with at least an intake and exhaust valve, comprising of performing a combustion cycle in the cylinder in which exhaust valve closing occurs after intake valve opening thereby creating valve overlap, boosting intake air above exhaust pressure, where said boosted intake air is inducted into said cylinder while said intake valve is open and at least a first portion of said inducted boosted intake air flows past the exhaust valve with both said intake and exhaust valves are open during said overlap, directly injecting fuel to said cylinder that is combusted in said cylinder, where a beginning of said fuel injection occurs after said exhaust valve closing and said directly injected fuel is mixed with at least a second portion of said inducted boosted intake air, and combusting said mixture at a rich air-fuel ratio.

A failure determination system and method for an internal combustion engine and an engine control unit are provided which are capable of properly determining a failure of a variable valve mechanism for inactivating a valve system associated with at least one of cylinders during a predetermined operation of the engine, by discriminating a misfire caused by the failure of the mechanism from a normal misfire. Fuel injection valves inject fuel for each cylinder and oxygen concentration of exhaust gases is detected. A misfire condition is detected on a cylinder-by-cylinder basis. Fuel injection to a misfiring cylinder is stopped. A failure of the mechanism is determined, when a parameter based on the oxygen concentration detection indicates a richer value of an actual air-fuel ratio of the exhaust gases than a predetermined reference value does, under a condition of the fuel injection being stopped.

Various systems and methods are disclosed for carrying out combustion in a fuel-cut operation in some or all of the engine cylinders of a vehicle. Further, various subsystems are considered, such as fuel vapor purging, air-fuel ratio control, engine torque control, catalyst design, and exhaust system design.

A system and method may be provided for operating a system having an engine with an emission control system, the emission control system including a lean NOx trap and a particulate filter, where after lean exhaust gas air-fuel ratio regeneration of the particulate filter at an elevated regeneration temperature, a rich or intermittently rich exhaust air-fuel ratio is provided for a duration lasting until LNT temperature falls to a minimum threshold, where said rich or intermittently rich operation reactivates catalysts in the LNT and reverses deactivation caused by the elevated temperature lean operation associated with previous particulate filter regeneration.

A catalyst deterioration detecting apparatus for a hybrid vehicle having an internal combustion engine and an electric motor as power sources includes an air-fuel ratio sensor downstream of a catalyst disposed in an exhaust passage of the engine. An amount of oxygen stored in the catalyst is estimated and, based on the estimated amount of oxygen and an output produced by the air-fuel ratio sensor after the engine is restarted after having been temporarily stopped, it is determined whether the catalyst has excessively deteriorated.

An air-fuel ratio control system for an internal combustion engine estimates an oxygen storage amount of a catalyst based on a record of an oxygen storage amount, and controls an air-fuel ratio based on the estimated oxygen storage amount. The catalyst is divided into multiple sections in a flow direction of an exhaust gas, the oxygen storage amount in a specified section is estimated according to a behavior of an exhaust gas on upstream and downstream sides of the respective specified sections, and the air-fuel ratio is controlled based on the estimated oxygen storage amount in the specified section.

Various systems and methods are disclosed for carrying out combustion in a fuel-cut operation in some or all of the engine cylinders of a vehicle. Further, various subsystems are considered, such as fuel vapor purging, air-fuel ratio control, engine torque control, catalyst design, and exhaust system design.

A canister comprises a tank port communicated with an upper air chamber in a closed fuel tank, a purge port communicated with an intake passage of an engine, an atmospheric port opened to the atmosphere, and a main adsorbent chamber containing activated carbon, and the canister is further provided with a partition plate between the tank port and the purge port for preventing both ports from being directly communicated with each other, so as to form a first chamber between the main adsorbent chamber and the tank port, and a second chamber between the main adsorbent chamber and the purge port, and a purge buffer plate is further provided in the main adsorbent chamber between the tank port and the purge port, for communicating between the first and second chambers with each other, the first chamber serves as an air chamber containing no activated carbon while the second chamber contains activated carbon. With this configuration, the canister has no external pipe line, the time change in fuel concentration of purged gas during treatment of evaporated fuel from the fuel tank is moderated in order to restrain an engine air-fuel ratio from being abruptly changed, and the operation ability of the engine can be satisfied.

An air-fuel ratio deviation calculated by an air-fuel ratio deviation calculation part is inputted to a cylinder-by-cylinder air-fuel ratio estimation part. A cylinder-by-cylinder air-fuel ratio is estimated in the cylinder-by-cylinder air-fuel ratio estimation part. In the cylinder-by-cylinder air-fuel ratio estimation part, attention is paid to gas exchange in an exhaust collective part of an exhaust manifold, and a model is created. In this model, a detection value of an A / F sensor is obtained by multiplying histories of the cylinder-by-cylinder air-fuel ratio of an inflow gas in the exhaust collective part and histories of the detection value of the A / F sensor by specified weights respectively and by adding them. The cylinder-by-cylinder air-fuel ratio is estimated on the basis of the model.