摘要:
A method that detects an air-fuel ratio in each cylinder of an internal combustion engine by properly setting a cycle of detecting an element resistance of an A/F oxygen concentration sensor. Although an actual A/F signal is at the stoichiometric ratio in each cylinder at exhaust timing cycle in a practical engine rotational speed range, the ratio is largely deviated to the rich side in the #1 cylinder. The first element resistance detection timing cycle coincides with generation timing of the actual A/F signal, so that the A/F signal cannot be detected. When the element resistance detection timing cycle is preset so as to be longer than the exhaust timing cycle, the second actual A/F signal detection timing for the #1 cylinder does not coincide with the element resistance detection timing. Consequently, the actual A/F signal of the #1 cylinder can be detected as an A/F signal by the A/F sensor.
摘要:
A gas concentration measuring apparatus which has a gas sensor designed to measure, for example, the concentrations of O2 and HOx contained in exhaust emissions of an automotive engine is provided. The apparatus includes a signal processing circuit which converts a current signal outputted from the gas sensor as a function of the concentration of either of O2 and NOx into a voltage signal. The gas sensor and the signal processing circuit are connected electrically through a conductor. The conductor has a length which is determined as a function of a level of the current signal outputted from the gas sensor. The weaker the level of the current signal is, the shorter the length of the conductor. This minimizes addition of electrical noises to the current signal outputted from the gas sensor.
摘要:
A gas concentration measuring apparatus which has a gas sensor designed to measure, for example, the concentrations of O2 and HOx contained in exhaust emissions of an automotive engine is provided. The apparatus includes a signal processing circuit which converts a current signal outputted from the gas sensor as a function of the concentration of either of O2 and HOx into a voltage signal. The gas sensor and the signal processing circuit are connected electrically through a conductor. The conductor has a length which is determined as a function of a level of the current signal outputted from the gas sensor. The weaker the level of the current signal is, the shorter the length of the conductor. This minimizes addition of electrical noises to the current signal outputted from the gas sensor.
摘要:
An A/F sensor generates a current signal corresponding to an air-fuel ratio in response to a voltage applied by a bias control circuit. After a sensor current is received as a voltage signal via a voltage follower, it is outputted to an A/D converter having a predetermined input voltage range, 0 to 5V. A sensor current detection circuit has a plurality of current detection resistors. In order to variably set the resistance value by the sensor current detection circuit, a switch circuit is switched in accordance with the sensor current depending on whether the A/F value to be detected is in the zone near the stoichiometric ratio or in other air-fuel ratio zones.
摘要:
An A/F signal proportional to an oxygen concentration in the exhaust gas from an internal combustion engine is output upon application of a voltage based on an instruction from a microcomputer. At the time an element resistance is detected, a bias instruction signal Vr from the microcomputer is converted by a D/A converter 21 to an analog signal Vb. An output voltage Vc obtained by removing high frequency components from the analog signal Vb through an LPF 22 is input to a bias control circuit 40. During this time period in which the element resistance is detected, an accurate A/F signal is not output. Therefore, the A/F signal that has theretofore prevailed is held by a Sample/Hold circuit 70 to thereby prevent the use of an erroneous A/F signal. Namely, at the time of detecting the element resistance, the detected value of the oxygen concentration is prevented from becoming abnormal. As a result, an accurate A/F control can be executed using the detected element resistance.
摘要:
An A/F signal proportional to an oxygen concentration in the exhaust gas from an internal combustion engine is output upon application of a voltage based on an instruction from a microcomputer. At the time an element resistance is detected, a bias instruction signal Vr from the microcomputer is converted by a D/A converter 21 to an analog signal Vb. An output voltage Vc obtained by removing high frequency components from the analog signal Vb through an LPF 22 is input to a bias control circuit 40. During this time period in which the element resistance is detected, an accurate A/F signal is not output. Therefore, the A/F signal that has theretofore prevailed is held by a Sample/Hold circuit 70 to thereby prevent the use of an erroneous A/F signal. Namely, at the time of detecting the element resistance, the detected value of the oxygen concentration is prevented from becoming abnormal. As a result, an accurate A/F control can be executed using the detected element resistance.
摘要:
An A/F sensor generates a current signal corresponding to an air-fuel ratio in response to a voltage applied by a bias control circuit. After a sensor current is received as a voltage signal via a voltage follower, it is outputted to an A/D converter having a predetermined input voltage range, 0 to 5V. A sensor current detection circuit has a plurality of current detection resistors. In order to variably set the resistance value by the sensor current detection circuit, a switch circuit is switched in accordance with the sensor current depending on whether the A/F value to be detected is in the zone near the stoichiometric ratio or in other air-fuel ratio zones.
摘要:
A gas concentration sensor voltage and current (in both heater on and heater off states) are detected and compared with predetermined thresholds, respectively, by a microcomputer. Based on a combination of the comparison results, the presence or absence of trouble in the system is detected and trouble location in the system is specified. In addition or alternatively, the sensor voltage is compared with thresholds to determine whether it is outside of a normal zone. The voltage may be actually detected or calculated. If the voltage is outside the normal zone, sensor voltage is reduced to zero or restricted to a predetermined limit.
摘要:
A gas concentration measuring apparatus for use in air-fuel ratio control of automotive engines is designed to determine the concentration of oxygen within a wide and a narrow range using a sensor current flowing through a sensor element. The apparatus includes an amplifier circuit equipped with an operational amplifier and a plurality of amplifying resistors and a switch. The switch is responsive to a request signal to switch a relation in electrical connection between an operational amplifier and the amplifying resistors to distribute the amplifying resistors into an input resistor and a feedback resistor for the operational amplifier to change an amplification factor of the amplifier circuit. This results in a change in resolution of measurement of the concentration of oxygen, thereby ensuring enhanced accuracy in determining the concentration of oxygen in a selected one of the narrow and wide ranges.
摘要:
A gas concentration measuring apparatus is provided which works to measure the concentration of a gas using a gas sensor element. The apparatus also works to determine the impedance of the gas sensor element through an arithmetic circuit for use in controlling the activation or diagnosis of the gas sensor element. The arithmetic circuit uses a command signal from a sensor controller to determine a sampling time at which a change in voltage applied to the sensor element or current flowing therethrough that is a function of the impedance of the sensor element is to be sampled. This permits the impedance to be calculated accurately in a simplified manner without use of a resource such as a timer.