Method and apparatus for operating a fuel-supply system with lambda control

Claim 2

In a method of operation of an internal combustion engine with a fuel supply apparatus and a lambda-control apparatus for the control of the fuel-air mixture based on a certain lambda value, wherein the fuel quantity to be supplied to the engine by the fuel supply apparatus is regulated in accordance with signals representing the engine RPM, intake manifold air-flow rate, and exhaust gas composition, and wherein the lambda-control apparatus operates in accordance with the temperature of an exhaust-gas sensor, the improvement comprising the steps of: determining an engine temperature by an engine temperature sensor; enriching the fuel-air mixture in accordance with the engine temperature determined by the engine temperature sensor so that the fuel-air mixture is heavily enriched when the engine is cold and this enrichment is reduced to zero as the engine temperature rises; supplying the engine temperature determined by the engine temperature sensor to a threshold switching element having a hysteresis characteristic, for generating an output signal which is switched in accordance with the engine temperature between one value corresponding to a low engine temperature and another value corresponding to a high engine temperature; controlling the actuation of the lambda-control apparatus in accordance with the output signal of the threshold element so that the lambda-control apparatus is only switched on when the value of the threshold element output signal corresponds to a high engine temperature; and supplementarily enriching the fuel-air mixture in accordance with the output signal of the threshold element.

Claim 3

In a method of operation of an internal combustion engine with a fuel supply apparatus and a lambda-control apparatus for the control of the fuel-air mixture based on a certain value, wherein the fuel quantity to be supplied to the engine by the fuel supply apparatus is regulated in accordance with signals representing the RPM, intake manifold air-flow rate, and exhaust gas composition and wherein the lambda-control apparatus operates in accordance with the temperature of an exhaust-gas sensor, the improvement comprising the steps of determining the engine temperature by an engine temperature sensor so that the attainment of a certain engine temperature is included as a supplementary criteria for the operation of the lambda-control apparatus, applying information related to engine temperature to a threshold element so that the switching ON or OFF of the lambda-control apparatus in accordance with engine temperature is determined by threshold values of the threshold element having a hysteresis characteristic, and supplementarily enriching the fuel-air mixture in accordance with an output signal of the threshold element.

Claim 4

In a method of operation of an internal combustion engine with a fuel supply apparatus and a lambda-control apparatus for the control of the fuel-air mixture based on a certain value, wherein the fuel quantity to be supplied to the engine by the fuel supply apparatus is regulated in accordance with signals representing the RPM, intake manifold air-flow rate, and exhaust gas composition and wherein the lambda-control apparatus operates in accordance with the temperature of an exhaust-gas sensor, the improvement comprising the steps of determining the engine temperature by an engine temperature sensor so that the attainment of a certain engine temperature is included as a supplementary criteria for the operation of the lambda-control apparatus, applying information related to engine temperature to a threshold element so that the switching ON or OFF of the lambda-control apparatus in accordance with engine temperature is determined by threshold values of the threshold element having a hysteresis characteristic, and supplementarily enriching the fuel-air mixture in accordance with an output signal of the threshold element.

Claim 5

The method as claimed in claim 2, which further comprises the step of maintaining the output signal of the threshold element at a certain value during the engine starting process.

Claim 6

The method as claimed in claim 3, wherein said certain value of the threshold element output signal is the value corresponding to a high engine temperature.

Claim 7

The method as claimed in claim 1 or 4, which further comprises the steps of: determining the operational readiness of the exhaust-gas sensor; and controlling the activation of the lambda-control apparatus in accordance with the operational readiness of the exhaust-gas sensor as well as in accordance with the threshold element output signal so that the lambda-control apparatus can be switched on by the threshold element only if the exhaust-gas sensor is operationally ready.

Claim 8

In an apparatus for the operation of an internal combustion engine including an intake manifold for supplying air to the engine, a transducer for sensing the air flow rate in the intake manifold, a transducer for sensing the RPM of the engine, a fuel supply apparatus for supplying fuel to the engine in accordance with the sensed engine RPM and intake manifold air flow rate, an exhaust-gas sensor for generating an output signal in accordance with the composition of the engine exhaust gas, and a lambda-control apparatus for controlling the fuel-air mixture supplied to the engine in accordance with the output signal of the exhaust-gas sensor, the improvement which comprises: a temperature transducer, arranged to sense an engine temperature, for generating an engine temperature signal corresponding to the sensed engine temperature; fuel enrichment means for enriching the fuel-air mixture in accordance with the engine temperature signal, so that the fuel-air mixture is heavily enriched when the engine is cold and this enrichment is reduced to zero as the engine temperature rises to a normal operating value; a threshold switch element, having a hysteresis characteristic and connected to receive the engine temperature signal, for generating an output signal which is switched in accordance with the engine temperature signal between one value corresponding to a low engine temperature and another value corresponding to a high engine temperature; a logic element connected to receive the sensor readiness signal and the threshold element output signal, for controlling the activation of the lambda-control apparatus so that the lambda-control apparatus is switched on only if the exhaust-gas sensor is operationally ready and if the value of the threshold element output signal corresponds to a high engine temperature; supplementary fuel enrichment means for enriching the fuel-air mixture in accordance with the threshold element output signal; and starting control means, associated with the threshold element, for maintaining the threshold element output signal at a constant value during engine starting, to thus obtain a constant starting condition depending upon the engine temperature.

Claim 9

In an apparatus for the operation of an internal combustion engine including an intake manifold for supplying air to the engine, a transducer for sensing the air flow rate in the intake manifold, a transducer for sensing the RPM of the engine, a fuel supply apparatus for supplying fuel to the engine in accordance with the sensed engine RPM and intake manifold air flow rate, an exhaust-gas sensor for generating an output signal in accordance with the composition of the engine exhaust gas, and a lambda-control apparatus for controlling the fuel-air mixture supplied to the engine in accordance with the output signal of the exhaust-gas sensor, the improvement which comprises: a temperature transducer, arranged to sense an engine temperature, for generating an engine temperature signal corresponding to the sensed engine temperature; fuel enrichment means for enriching the fuel-air mixture in accordance with the engine temperature signal, so that the fuel-air mixture is heavily enriched when the engine is cold and this enrichment is reduced to zero as the engine temperature rises to a normal operating value; a threshold switch element, having a hysteresis characteristic and connected to receive the engine temperature signal, for generating an output signal which is switched in accordance with the engine temperature signal between one value corresponding to a low engine temperature and another value corresponding to a high engine temperature; a logic element connected to receive the sensor readiness signal and the threshold element output signal, for controlling the activation of the lambda-control apparatus so that the lambda-control apparatus is switched on only if the exhaust-gas sensor is operationally ready and if the value of the threshold element output signal corresponds to a high engine temperature; supplementary fuel enrichment means for enriching the fuel-air mixture in accordance with the threshold element output signal; and starting control means, associated with the threshold element, for maintaining the threshold element output signal at a constant value during engine starting, to thus obtain a constant starting condition depending upon the engine temperature.

Claim 10

An apparatus as claimed in claim 6, wherein the starting control means maintains the threshold element output signal during starting of the engine at the value corresponding to a high engine temperature.

Claim 11

An apparatus as claimed in claim 7, wherein the threshold element comprises a differential amplifier having an output, a first input connected to a reference voltage source, and a second input connected to an output of the starting control means and to the output of the temperature transducer, for generating the threshold element output signal.

Claim 12

An apparatus as claimed in claim 6, wherein the sensor-readiness recognition circuit is arranged to sense the temperature of the exhaust gas sensor and generate a sensor-readiness signal indicating the operational readiness of the exhaust-gas sensor when the temperature of the exhaust-gas sensor exceeds approximately 250° C.

Claim 13

An apparatus as claimed in claim 6, wherein the switching values of the threshold element with hysteresis preferably lie at about 10° C. and at a value in the range of 50° C. to 85° C.

Claim 14

An apparatus as claimed in claim 6 wherein the logic element is an OR gate.

Claim 15

An apparatus as claimed in claim 6 wherein the engine temperature is derived from the temperature of at least one of the following: the coolant, the lubricant, and the cylinder head.

Claim 16

An apparatus as claimed in claim 12 including means for changing the high and low temperature response values of the threshold element so that during the engine starting process, the output signal of the threshold element may be set at a certain value.

Claim 17

An apparatus as claimed in claim 6, wherein at engine starting temperatures below a certain value, the warm-up of the engine must have attained a temperature of preferably 50° to 85° C., in order to make the lambda-control apparatus be dependent upon the exhaust-gas sensor temperature.