1359 results about "Air–fuel ratio" patented technology

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.

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.

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 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 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.

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 method for operating a spark-ignition engine having a three-way catalyst and a particulate filter downstream thereof, comprising: oscillating an exhaust air-fuel ratio entering the particulate filter to generate air-fuel ratio oscillations downstream of the particulate filter, while increasing exhaust temperature; when the downstream oscillations are sufficiently dissipated, enleaning the exhaust air-fuel ratio entering the particulate filter; and reducing the enleanment when an exhaust operating parameter is beyond a threshold amount.

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.

A prechamber spark plug may have a prechamber having a pre-determined aspect ratio and hole pattern to achieve particular combustion performance characteristics. The aspect ratio and hole pattern may induce a rotational flow of fuel-air in-filling streams inside the prechamber volume. The rotational flow of the fuel-air mixture may include both radial flow and axial flow characteristics based on the aspect ratio and hole pattern. Axial flow characteristics can include a first axial direction proximate the periphery of the rotational flow and a counter second axial direction approaching the center of the rotational flow. The radial and axial flow characteristics may further include radial air-fuel ratio stratification and/or axial air-fuel ratio stratification. The rotational flow, the radial flow and the axial flow may be adjusted by alteration of the aspect ratio and hole pattern to achieve particular combustion performance characteristics in relation to a wide variety of spark gap geometries.

According to the present invention, there is disposed in an exhaust passage of an internal combustion engine a filter that traps particulate matter In an exhaust gas, and a catalyst with a three-way function is carried on the filter. At the filter regeneration, by controlling such as an injection amount of post injection, an air-fuel ratio of the exhaust gas at an outlet of the filter is controlled to a stoichiometric ratio, and also by controlling such as an intake air throttle valve, an oxygen concentration of the exhaust gas at an inlet of the filter is controlled. Hence, at the filter regeneration, the particulate can be reliably burned and removed, and at the same time, NOx in addition to HC and CO can be purified.

What is disclosed is a micro-pilot injection ignition type gas engine, whereby an air fuel ratio control in starting the engine is executed with enhanced precision, by means of introducing skip-firing intermittent operations which reflect the engine operation conditions, while an idling time span can be shortened or omitted.

The engine includes: a gas valve that opens and closes a fuel-gas passage in front of each cylinder, so as to arbitrarily control the throat area as well as the opening-closing time span of the gas valve; an engine speed detecting unit to detect the engine speed; a combustion diagnosis unit to detect an engine combustion state through a cylinder pressure distribution along elapsed time, as to each cylinder; an opening-closing control unit as to the gas valve, so as to control the intermittent opening-closing of the gas valve according to the levels of the detected engine speed as well as the cylinder pressure distribution; whereby, in starting the engine, the intermittent opening-closing of the gas-valve enables at least one skip-firing mode that brings an enhanced fuel-supply pressure-pulsation with which a relatively large amount of fuel-gas is supplied per engine cycle with firing so that the air fuel-gas ratio of each cylinder reaches a prescribed target value.

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.

An exhaust emission control system for an internal combustion engine, having a nitrogen oxide removing device provided in an exhaust system of said engine for absorbing nitrogen oxide contained in exhaust gases in an exhaust lean condition. An amount of change per unit time in the sulfur oxide amount absorbed in the nitrogen oxide removing device is estimated according to the air-fuel ratio of an air-fuel mixture supplied to said engine and the operating condition of said engine. The estimated amount of change is accumulated to thereby estimate the sulfur oxide amount absorbed in the nitrogen oxide removing device. The sulfur oxide is removed from the nitrogen oxide removing device when the estimated sulfur oxide amount has reached a set value.

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.

In a multi-cylinder engine, to compute the air-fuel ratio of each cylinder by an air-fuel ratio sensor disposed in an exhaust pipe, a cylinder is determined by a crank angle detected by a crank angle sensor. A deviation in the air-fuel ratio of each cylinder is detected on the basis of the output signal of the air-fuel ratio sensor disposed in the exhaust pipe and the forcibly changed quantity of the air-fuel ratio.

A fuel adding valve (14), an HC adsorbing and oxidation catalyst (11), and a NO_x storing catalyst (12) are successively arranged in an exhaust passage of an internal combustion engine toward the downstream side. When the NO_x storing catalyst (12) should release NO_x, particulate fuel is added from the fuel adding valve (14). This fuel is adsorbed once at the HC adsorbing and oxidation catalyst (11), then gradually evaporates to make the air-fuel ratio of the exhaust gas flowing into the NO_x storing catalyst (12) rich. Due to this, NO_x is released from the NO_x storing catalyst (12).

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.

An air/fuel ratio control system controls the supply of fuel to an internal combustion engine to achieve a target air/fuel ratio, based on the output of an air/fuel ratio sensor. The system may determine whether there is an abnormality in the air/fuel ratio sensor based on a comparison between a change of an air/fuel ratio correction coefficient, used to drive the air/fuel ratio to the target value, and a change of the target air/fuel ratio if the target air/fuel ratio has sharply changed. Alternatively, the diagnosis operation may be performed based on a comparison between a total air/fuel ratio correction amount and a change of the air/fuel ratio detected by the air/fuel ratio sensor, a phase difference calculation between peaks of the air/fuel ratio or the air/fuel ratio correction coefficient, or by accumulating the differences between the air/fuel ratio and the target air/fuel ratio, and the differences between the air/fuel ratio correction coefficient and a reference value, and comparing the accumulated values. In addition, the system may detect a sensor abnormality based on the deviation in phase of the air/fuel ratio from the air/fuel ratio correction coefficient. These diagnosis operations can precisely and easily detect the occurrence of an abnormality in the air/fuel ratio sensor. As a result, the air/fuel ratio control system will not use an imprecise output from the sensor for air/fuel ratio control, thus achieving highly precise and highly reliable air/fuel ratio control.

An integrative control method and device for controlling gas engines is proposed which load responsivity of the engine is improved while maintaining air fuel ratio control and stable control is performed when fuel gas of different calorific value is used. The control method comprises a speed control process for controlling engine rotation speed by controlling the fuel gas flow control valve based on deviation of actual engine rotation speed from a target command value of rotation speed, and an air fuel ratio control process for controlling air fuel ratio of fuel-air mixture by controlling throttle valve opening based on deviation of the actual mixture flow rate from the command value of mixture flow rate, whereby correction of theoretical air fuel ratio in accordance with exhaust temperature is performed in the air fuel ratio control process, the correction being done to correct the theoretical air fuel ratio used to calculate the command value of fuel-air mixture flow rate in accordance with exhaust temperature based on deviation of actual exhaust temperature from target exhaust temperature prescribed for various engine rotation speeds and load factors.

Disclosed is a supercharged direct-injection engine, which comprises a supercharging device (25, 30) for compressing intake air, and an injector 10 for directly injecting fuel into a combustion chamber 5. In the engine, an excess air factor λ as a ratio of an actual air-fuel ratio to a stoichiometric air-fuel ratio, at least in an engine warmed-up mode, is set to 2 or more in the entire engine-load region. Further, compressed self-ignited combustion is performed in a low engine-load region, and a supercharging amount by the supercharging device (25, 30) is increased along with an increase in engine load in a high engine-load region to allow the excess air factor λ to be kept at 2 or more. The engine of the present invention can effectively reduce NOx emission, while improving fuel economy.

A method and apparatus that applies corrections to the mass flow rate of combustion air into a gas or oil-fired, forced-draft burner, and thus provides for correcting the air-fuel ratio, by directly measuring the combustion air temperature and/or the barometric pressure of the combustion air, and using these measurements to develop a fan speed drive signal that corrects the volume of air inlet to the burner system without the use of the complex and expensive fully metered control systems, or elaborate feedback systems, or systems that require real-time combustion analysis, and the like.

If conditions of stopping an engine are satisfied, it is judged whether the lean operation in which the air-fuel ratio is set to be on a lean side with respect to the theoretical air-fuel ratio is currently performed or not. If the lean operation is currently performed, reduction enrichment of NOx is executed during an enrichment time TRICH, and the engine is thereafter actually 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 computer calculates an estimated cylinder-intake-air amount based on outputs from an airflow meter and a throttle position sensor, and then calculates a reference cylinder-intake-air amount based on an air-fuel ratio in an exhaust gas and fuel injection amount. An error of the estimated cylinder-intake-air amount is calculated by comparing the reference cylinder-intake-air amount with an estimated cylinder-intake-air amount base value. The error is low-pass filtered. The estimated cylinder-intake-air amount base value is corrected to obtain the final estimated cylinder-intake-air amount.

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.

An air fuel ratio control apparatus for an internal combustion engine can freely change an oscillation width of an amount of oxygen occlusion so as to adapt to or diagnose catalyst degradation without changing the settings of the period or width of the air fuel ratio oscillation. The apparatus includes a first air fuel ratio feedback control section that adjusts the air fuel ratio of a mixture supplied to an engine in accordance with an output value of an upstream air fuel ratio sensor and a predetermined control constant thereby to make the air fuel ratio periodically oscillate in rich and lean directions, and an average air fuel ratio oscillation section that operates the control constant based on an amount of oxygen occlusion of the catalyst so that an average air fuel ratio obtained by averaging the periodically oscillating air fuel ratio is caused to oscillate in the rich and lean directions.