Abstract: A waste heat recovery structure includes a first exhaust gas flow path provided to each of steel making electric arc furnaces to discharge exhaust gas thereinto; a waste heat boiler disposed on the first exhaust gas flow path to recover waste heat as saturated steam from exhaust gas; a steam accumulator configured to store steam formed by confluence of saturated steam parts, each generated by the waste heat boiler; a steam super heater configured to turn steam into superheated steam by heating; a second exhaust gas flow path configured to lead exhaust gas from the waste heat boiler to the steam super heater to use it for superheating; a third exhaust gas flow path configured to discharge exhaust gas from the waste heat boiler not through the steam super heater; and a switching device configured to switch flow paths between the second and third exhaust gas flow paths.

Abstract: A waste heat recovery structure includes a first exhaust gas flow path provided to each of steel making electric arc furnaces to discharge exhaust gas thereinto; a waste heat boiler disposed on the first exhaust gas flow path to recover waste heat as saturated steam from exhaust gas; a steam accumulator configured to store steam formed by confluence of saturated steam parts, each generated by the waste heat boiler; a steam super heater configured to turn steam into superheated steam by heating; a second exhaust gas flow path configured to lead exhaust gas from the waste heat boiler to the steam super heater to use it for superheating; a third exhaust gas flow path configured to discharge exhaust gas from the waste heat boiler not through the steam super heater; and a switching device configured to switch flow paths between the second and third exhaust gas flow paths.

Abstract: An abnormality diagnosis apparatus is used for a secondary air supply system for an internal combustion engine. The system includes an air pump for supplying secondary air into an upstream of a catalyst in an exhaust gas passage of the internal combustion engine. A secondary air detecting means detects secondary air information. An abnormality diagnosis means performs an abnormality diagnosis of the secondary air supply system in accordance with the secondary air information detected using the secondary air detecting means. A temperature information determining means performs at least one of detection and estimation of air pump temperature information. A condition setting means performs at least one of setting and compensating a condition for evaluating normality and abnormality of the secondary air supply system in accordance with the air pump temperature information.

Abstract: A plug of a power cord of a block heater, which is mounted to a cylinder block of an engine, is connected to a household power receptacle to energize the block heater during an engine stoppage in cold climate. Thus, an engine coolant is kept warm to prevent freeze. Existence/nonexistence of the energization to the block heater during the engine stoppage is determined based on a behavior of coolant temperature or a behavior of engine rotation speed immediately after an engine start. If it is determined that the energization to the block heater exists, abnormality diagnosis of a cooling system is prohibited or a condition for the abnormality diagnosis is corrected and estimation coolant temperature is corrected.

Abstract: A method for detecting a malfunction of a cooling system of an internal combustion engine, comprising: detecting a coolant temperature on a side of the engine; determining a malfunction of the cooling system with the coolant temperature and the value only after a cold start of the engine.

Abstract: An error detection apparatus detects an error of a NOx sensor, which is located on a downstream side of a NOx remover in a discharge passage of the internal combustion engine. In the error detection apparatus, a running state detector detects a running state of the internal combustion engine. An unsteady state determiner determines whether the running state of the internal combustion engine detected by the running state detector is unsteady or not. A NOx amount retriever retrieves the amount of NOx on the downstream side of the NOx sensor by receiving an output signal of the NOx sensor. An error determiner determines the error of the NOx sensor on the basis of the amount of the NOx that is retrieved by the NOx amount retriever during a predetermined period under the running state of the internal combustion engine including the unsteady state determined by the unsteady state determiner.

Abstract: An engine control apparatus feedback-controls a mixture air-fuel ratio of air-fuel mixture supplied to each cylinder of the engine based on an exhaust air-fuel ratio detected by an air-fuel ratio sensor. The control apparatus further calculates an exhaust air-fuel ratio change rate at every predetermined interval and integrates an absolute value of the exhaust air-fuel ratio change rate. The control apparatus determines an abnormality in any one of engine cylinders when an integration value of the exhaust air-fuel ratio change rate exceeds a predetermined reference value.

Abstract: A plug of a power cord of a block heater which is mounted to a cylinder block of an engine, is connected to a household power receptacle to energize the block heater during an engine stoppage in cold climate. Thus, an engine coolant is kept warm to prevent freeze. Existence/nonexistence of the energization to the block heater during the engine stoppage is determined based on a behavior of coolant temperature or a behavior of engine rotation speed immediately after an engine start. If it is determined that the energization to the block heater exists, abnormality diagnosis of a cooling system is prohibited or a condition for the abnormality diagnosis is corrected and estimation coolant temperature is corrected.

Abstract: A method For detecting a malfunction of a cooling system of an internal combustion engine, comprising: detecting a coolant temperature on a side of the engine; determining a malfunction of the cooling system with the coolant temperature and the value only after a cold start of the engine.

Abstract: An individual-cylinder air-fuel ratio estimation model is designed so as to consider the mixing of gases exhausted from adjacent combustion cylinders, and a movement by which a mixed gas arrives at the position of an air-fuel ratio sensor, in order that influences ascribable to the intervals (combustion intervals) of the adjacent combustion cylinders may be reflected on the estimation values of individual-cylinder air-fuel ratios. In evaluating the mixing of the gases which are exhausted from the adjacent combustion cylinders, there are considered the lengths and shapes of the exhaust manifolds of the respective combustion cylinders. In evaluating the movement by which the mixed gas arrives at the position of the air-fuel ratio sensor, there are considered a distance or volume from the confluence to the position of the air-fuel ratio sensor, and the exhaust gas quantities of the respective combustion cylinders.

Abstract: An engine start is beforehand detected when a preparation operation to engine start is detected. When the preparation operation is detected based on a seat switch indicating that a driver seats himself on a driver seat, control of an electric current for a heater of an air/fuel ratio sensor is started. The air/fuel ratio sensor is then activated prior to the engine start. Failure diagnosis is conducted on a function for detecting the preparation operation. Namely, the seat switch is diagnosed as having failure, for instance, by the following. Even while a vehicle travels, the seat switch is in an OFF state indicating that no driver is seated. This structure can restrict the engine start without the air/fuel ratio sensor being pre-heated. It can also restrict deteriorating of emission.

Abstract: An engine control apparatus feedback-controls a mixture air-fuel ratio of air-fuel mixture supplied to each cylinder of the engine based on an exhaust air-fuel ratio detected by an air-fuel ratio sensor. The control apparatus further calculates an exhaust air-fuel ratio change rate at every predetermined interval and integrates an absolute value of the exhaust air-fuel ratio change rate. The control apparatus determines an abnormality in any one of engine cylinders when an integration value of the exhaust air-fuel ratio change rate exceeds a predetermined reference value.

Abstract: A malfunction of a thermostat in a coolant circulating path is detected from an engine side coolant temperature in consideration of the following behavior of the coolant temperature. When an open-malfunction occurs, the coolant temperature becomes different considerably from that in the normal time in the temperature range in which the thermostat is to be normally closed. When a closure-malfunction occurs, the coolant temperature becomes different considerably from that during the normal time in the temperature range in which the thermostat is to be normally opened. Alternatively, the malfunction may be detected from a difference between the engine side coolant temperature and a radiator side coolant temperature.

Abstract: A target air-fuel ratio setting part has a sub-feedback part, a target air-fuel ratio enriching part, and a target air-fuel ratio changeover part. The sub-feedback part variably sets a target air-fuel ratio upstream of a catalyst on the basis of a detection signal of an O2 sensor provided downstream of the catalyst. The target air-fuel ratio changeover part uses, as the target air-fuel ratio, a rich target air-fuel ratio which is set by the target air-fuel ratio enriching part on conditions such that the target air-fuel ratio set by the sub-feedback part is rich. A cylinder-by-cylinder air-fuel ratio estimation part calculates a cylinder-by-cylinder air-fuel ratio on the basis of a detection value of an air-fuel ratio sensor and the target air-fuel ratio.

Abstract: An evaporated gas control system mounted on an automotive vehicle includes a canister for absorbing gas evaporated from a fuel tank and a purging passage for purging the evaporated gas into an engine. The purging passage is branched out to two passages, an upstream purging passage connected to an upstream portion of a throttle valve through an upstream valve and a downstream purging passage connected to a downstream portion of the throttle valve. Malfunction of the upstream purging passage including the upstream valve is detected based on changes in pressure of the air intake passage, which are responsive to opening and closing operations of the upstream valve. Preferably, the malfunction detecting process is performed by operating the upstream valve from a fully closed state to a fully open state under the condition where the throttle valve is fully closed.

Abstract: A secondary air control system supplies secondary air to the upstream of a catalyst purifying exhaust gas in an exhaust passage of an engine. A diagnostic device includes a secondary air detecting means that detects a secondary air information related to pressure of secondary air. An abnormality diagnostic means performs an abnormality diagnostic operation of the secondary air control system in accordance with the secondary air information. A voltage detecting means that detects a power source voltage information related to power source voltage supplied to the secondary air control system. An evaluating condition correcting means that corrects an evaluating condition, which is used for evaluating abnormality in the secondary air control system in accordance with a power source voltage information.

Abstract: An individual-cylinder air-fuel ratio estimation model is designed so as to consider the mixing of gases exhausted from adjacent combustion cylinders, and a movement by which a mixed gas arrives at the position of an air-fuel ratio sensor, in order that influences ascribable to the intervals (combustion intervals) of the adjacent combustion cylinders may be reflected on the estimation values of individual-cylinder air-fuel ratios. In evaluating the mixing of the gases which are exhausted from the adjacent combustion cylinders, there are considered the lengths and shapes of the exhaust manifolds of the respective combustion cylinders. In evaluating the movement by which the mixed gas arrives at the position of the air-fuel ratio sensor, there are considered a distance or volume from the confluence to the position of the air-fuel ratio sensor, and the exhaust gas quantities of the respective combustion cylinders.

Abstract: A malfunction of a thermostat in a coolant circulating path is detected from an engine side coolant temperature in consideration of the following behavior of the coolant temperature. When an open-malfunction occurs, the coolant temperature becomes different considerably from that in the normal time in the temperature range in which the thermostat is to be normally closed. When a closure-malfunction occurs, the coolant temperature becomes different considerably from that during the normal time in the temperature range in which the thermostat is to be normally opened. Alternatively, the malfunction may be detected from a difference between the engine side coolant temperature and a radiator side coolant temperature.

Abstract: A fuel vapor control system has a controller that carries out a leak check processing after the engine is stopped. The controller includes a device that intermittently activates the controller itself or a part of the controller to sample an internal pressure of the fuel vapor passage. Then, after a predetermined time, the controller determines that whether the sampled values of the internal pressure indicate a leak or not by evaluating the sampled values. According to the arrangement, since at least a part of the controller is activated intermittently, the consumption of electricity can be reduced. The fuel vapor control system has a canister valve and a purge valve made of normally close type valves in order to reduce the consumption of electricity after the engine is stopped.

Abstract: A leak check system executes a leak check processing. In the leak check processing, the system closes a canister valve and a purge valve to close the fuel vapor purge system. Then, the system detects and monitors a pressure in the fuel vapor purge system. During the leak check processing, the system detects a rapid change of the pressure that is caused by a deformation of a wall of a fuel tank. The system cancels or suspends the processing to avoid erroneous detection of the leak. If the leak check is canceled, the system opens the canister valve to open the fuel vapor purge system.