Abstract: A system and method for controlling operation of an engine having a fuel vapor recovery system coupled between a fuel supply system and engine air/fuel intake. In response to a two-state exhaust gas oxygen sensor (EGO sensor), a feedback controller generates a desired fuel charge. This feedback controller is also responsive to an adaptive learning controller which provides corrections for long term air/fuel offsets caused by such factors as fuel injector variances. An adaptive fuel vapor learning controller measures fuel vapor concentration during purging operations of the fuel vapor recovery system. This adaptive fuel vapor learning controller provides a fuel vapor correction factor which is subtracted from the desired fuel charge to maintain proper air/fuel ratio operation during a fuel vapor purge. Purging operations are disabled when the measurement of fuel vapor concentration is below a preselected value. At that time, the offset learning controller is enabled for a preselected time.

Abstract: A system and method for controlling operation of an engine wherein a fuel vapor recovery system is coupled between an air/fuel intake and a fuel supply system. An air/fuel ratio indication is provided by a proportional plus integral feedback controller coupled to a two-state exhaust gas oxygen sensor. In response to the air/fuel ratio indication and a measurement of inducted air flow, a base fuel command is generated. To compensate for purging of fuel vapors, a reference air/fuel ratio is subtracted from the air/fuel ratio indication and the resulting error signal generated. This compensation factor represents a learned value which is directly related to fuel vapor concentration, and it is subtracted from the base fuel command to correct for induction of fuel vapors. At initiation of fuel vapor purging, the rate of purge flow is incremented a predetermined amount with each change in state of the exhaust gas oxygen sensor.

Abstract: An apparatus for controlling operation of an internal combustion engine at lean air fuel ratios includes a fuel controller for generating a fuel injector drive signal. The apparatus also includes a memory table means, a hydrocarbon sensor means, an airflow indication means, and a compensation means. Memory table means stores a schedule of fuel air ratio commands as a function of engine operating conditions. The hydrocarbon sensor means is coupled to the engine for measuring variations in the engine exhaust hydrocarbon emissions and generating an output signal as a function of such variations in hydrocarbon emissions. The airflow indication means generates a signal indicative of airflow into the engine. The compensation means is coupled to the hydrocarbon sensor, the memory table means, and the airflow indicator means for modifying the fuel air ratio control commands stored in the memory table means as a function of airflow and engine exhaust hydrocarbon variation.

Abstract: An apparatus and a method for controlling hydrocarbon emission from an internal combustion engine having an air/fuel intake coupled to a fuel vapor recovery system. Fuel vapors are periodically purged from the fuel vapor recovery system into the air/fuel intake. The mixture of air fuel vapor and fuel inducted into the air/fuel intake is regulated by a feedback loop responsive to an exhaust gas oxygen sensor to maintain a desired air/fuel ratio. An indication of the fuel vapor concentration in the fuel vapor recovery system is provided to control various engine parameters and thereby reduce hydrocarbon emissions during the response time of the feedback loop. In one aspect of the invention, the flow rate of the purged fuel vapors is controlled to be in inverse relation to the concentration of purged fuel vapors during the response time of the feedback loop.

Abstract: Controlling operation of an internal combustion engine at lean air fuel ratios uses an in-cylinder pressure sensor. The in-cylinder pressure sensor is coupled to each cylinder of the engine and measures in-cylinder pressure and generates an output signal as a function of such pressure. Airflow into the engine is also sensed and both the airflow and in-cylinder pressure are applied to the fuel controller for generating a fuel injection drive signal. Compensation means coupled to the in-cylinder pressure sensor means and airflow indication means modify the fuel air command applied to the engine as a function of airflow and in-cylinder pressure. The compensation means is also coupled to the fuel controller for applying a fuel command signal to the fuel controller thereby permitting engine operation at the lean air fuel ratio limit.

Abstract: An apparatus and a method for controlling hydrocarbon emission from an internal combustion engine having an air/fuel intake coupled to a fuel vapor recovery system. Fuel vapors are periodically purged from the fuel vapor recovery system into the air/fuel intake. The mixture of air/fuel vapor and fuel is regulated by a feedback loop response to an exhaust gas oxygen sensor to maintain a desired air/fuel ratio. At the beginning of each purge cycle, engine spark timing is temporarily retarded to reduce hydrocarbon emissions during the response time of the feedback loop.

Abstract: Fuel vapors are purged from a vapor storage canister to the intake of an internal combustion engine by inducting air into the vapor canister, modulating the purge flow of an air and fuel vapor mixture from the canister, and establishing a predetermined magnitude of combustion exhaust emissions by gradually changing the magnitude of a transient flow between no purge flow and a full purge flow so that the amount of combustion exhaust emissions is maintained below the predetermined magnitude.

Abstract: Purging of fuel vapors from a vapor canister storing fuel vapors from the fuel tank of an internal combustion engine is done by modulating the overall purge flow rate from the vapor canister as a function of the amount of fuel vapor stored in the vapor canister.

Abstract: Controlling air/fuel ratio perturbations in response to purging of fuel vapors from a vapor canister storing fuel vapors from the fuel tank of an internal combustion engine includes feeding forward an offsetting fuel command signal. The feedforward offsetting fuel command signal is used to change, and thereby compensate, a base fuel command signal applied to a fuel injector controller whenever fuel vapor purging is occurring.

Abstract: This specification discloses an air-fuel ratio control system for an internal combustion engine which can provide air-fuel feedback control at air-fuel ratios lean of stoichiometry while using an air-fuel sensor capable of only indicating stoichiometry. A control means pulses the air-fuel ratio to determine the magnitude of pulse necessary to cross stoichiometry. Thus the air-fuel ratio can be maintained at a desired offset from stoichiometry.

Abstract: An exhaust gas heat exchanger for vaporizing a liquid fuel is disclosed. The exhaust gas heat exchanger includes exhaust gas flow control valve means, responsive to a vapor temperature, to control the delivery of heated exhaust gases to a heat exchanger coil. A heat exchanger housing is communicated with the exhaust gas conduit of an otherwise conventional internal combustion engine and is provided with means defining a pair of generally parallel exhaust gas flow chambers. A fluid conducting heat exchanger assembly, in the form of one or more helical coils of fluid conducting tubing, is disposed within one of said at least two chambers in the housing. The tubing communicates on an upstream end with a source of liquid fuel and communicates on a downstream end with a vapor reservoir. The heat exchanger coil is arranged to have a maximum surface to volume ratio by including a plurality of individual fluid conduits arranged in side by side relationship.

Abstract: An exhaust gas heat exchanger for vaporizing a liquid fuel is disclosed. The exhaust gas heat exchanger includes exhaust gas flow control valve means, responsive to a vapor temperature, to control the delivery of heated exhaust gases to a heat exchanger coil. A heat exchanger housing is communicated with the exhaust gas conduit of an otherwise conventional internal combustion engine and is provided with means defining a pair of generally parallel exhaust gas flow chambers. A fluid conducting heat exchanger assembly, in the form of one or more helical coils of fluid conducting tubing, is disposed within one of said at least two chambers in the housing. The tubing communicates on an upstream end with a source of liquid fuel and communicates on a downstream end with a vapor reservoir. The heat exchanger coil is arranged to have a maximum surface to volume ratio by including a plurality of individual fluid conduits arranged in side by side relationship.

Abstract: A mixing apparatus for mixing a vaporized liquid fuel with air to develop a combustible air/fuel mixture is described. A finned swirl inducing member having a centrally located aperture is positioned downstream from a metering venturi and upstream from a plain tube mixing section. The centrally positioned aperture is sized and spaced to allow passage of a stream of vaporized liquid fuel delivered to the low pressure zone formed by a metering venturi. The fin members of the swirler are operative to cause a swirl of the air stream passing through the metering venturi. The swirling air stream prevents any direct contact between the vapor stream and the relatively cool side walls of the mixing section while causing mixing action between the interiorly constrained vaporized liquid fuel stream and the inner portions of the air swirl.

Abstract: A fuel delivery system for an internal combustion engine is disclosed. The system includes primary and auxiliary heating means for vaporizing a liquid fuel, vapor storage means, carburetor means including metering venturi means for mixing the vaporized liquid fuel with atmospheric air to provide a combustible air/fuel mixture and means for controlling the delivery of vaporized fuel to the carburetor means. The carburetor means may be connected to a conventional internal combustion engine intake manifold for eventual delivery of the combustible mixture to the combustion chambers of the engine. The vaporized liquid fuel delivery means of the system includes a variable orifice vapor delivery nozzle for modulating the vaporized fuel content of the air/fuel ratio of the combustion mixture.The auxiliary heating means are operative to provide an initial supply of vapor to a vapor reservoir upon start-up of the internal combustion engine.

Abstract: A vapor reservoir adapted for use in conjunction with a vaporized liquid fuel system for an internal combustion engine is disclosed. The reservoir includes a movable wall member cooperative with means defining a housing to establish a variable volume vapor storage space. The movable wall member is referenced to the pressure of the air immediately upstream from the intake to the air and fuel metering portion of the engine. The housing includes a generally downwardly depending condensate collecting and return section. Vapor delivery conduits are positioned within the housing and support a thermally floating finned member operative to disperse vapor delivered to the vapor reservoir. The movable wall member is provided with position sensing means operative to provide an input to an electrical circuit for controlling the rate of vapor delivery to maintain a predetermined quantity of vapor within the vapor space.

Abstract: An electrically powered liquid fuel vaporizer including overtemperature protection is described. A plurality of thin walled fuel conduits or tubes are arranged in a bundle and are communicated at one end to a source of liquid fuel and at their opposite end to a vaporized liquid fuel reservoir. Each end of the fuel tube bundle is provided with one member of a pair of electrical terminals. One of the pair of electrical terminals is communicated to a solenoid operated switch which in turn is communicated to one terminal of electric power source. The other of the pair of terminals is communicated to the opposite terminal of the electric power source. An insulating sheath or housing means is arranged around the fuel tube bundle. One end of the housing means is fixedly attached to the fuel tube bundle in proximity to one of the pair of electrical terminals. The housing member is provided with a third electrical terminal which communicates with the solenoid.