Abstract: An air-fuel ratio feedback correction coefficient for correcting a fuel supply quantity to an engine is proportional-plus-integral controlled based on an output from an oxygen sensor for detecting oxygen concentration in the exhaust gases. When the oxygen sensor is in an inactive condition, deviation of an air-fuel ratio control point in the air-fuel ratio feedback control is detected, and an operating quantity in the proportional-plus-integral control is corrected so as to reduce the detected deviation.

Abstract: A crystal puller cell (18) provides a low particulate environment for an individual crystal puller (28). The airflow within each cell is adjustable so that a particulate level appropriate to the activity within the cell is maintained, thereby avoiding the cost of maintaining an entire growing hall (10) at a constant high level of cleanliness. Each cell includes a multilevel floor (46) that includes an operator floor (48) and a maintenance floor (52). A door (62) at the maintenance floor level opens onto a maintenance aisle used to service the machines. A door (64), at the operator floor level, opens onto a clean aisle for transporting raw material and finished product. The cell walls can include magnetic shielding if a magnetic growing process is used to reduce exposure of operators and other machines to intense magnetic fields.

Abstract: In an air/fuel ratio control system for an internal combustion engine, having a second air/fuel ratio sensor disposed downstream of a catalytic converter, a computing type used for computing a second air/fuel ratio correction quantity in accordance with an output of the second air/fuel ratio sensor is switched in such a manner that the second air/fuel ratio quantity is set larger when the output of the second air/fuel ratio sensor is outside a reference level range than when the output of the second air/fuel ratio sensor is within the reference level range.

Abstract: In a device having air-fuel ratio sensors upstream and downstream of an exhaust gas purifying catalytic converter with learning carried out based on output values from the downstream air-fuel ratio sensor, independent learning is carried out depending on whether the catalytic converter is active or not. The air-fuel ratio is then controlled based on the output value of the first air-fuel ratio sensor, the output value of the second air-fuel ratio sensor and the learned value. As a result leaning accuracy is increased and air-fuel ratio control performance enhanced.

Abstract: Provided is an apparatus for detecting a volatility of fuel supplied to an engine, in order to ensure a more precise acceleration dependent fuel increasing-correction during air-fuel-ratio feed-back control. When the air-fuel-ratio feed-back control begins after engine starting (S4), a determination is made as to whether the engine is in a low exhaust-temperature state on the basis of an engine coolant temperature Tw (S5). When the exhaust temperature is low, an average value .alpha..sub.av of an air-fuel-ratio feed-back correction factor .alpha. is derived (S6, S7), and then the average value .alpha..sub.av is compared with a reference value (S8). In case that the fuel supplied to the engine is a heavy-gravity fuel of a low volatility, since there are great amounts of hydrocarbons HC in exhaust gases and with a great consumption of oxygen a control point of the air-fuel-ratio feed-back control, which point can be indicated by the average value .alpha..sub.av, shifts to a leaner side.

Abstract: In an internal combustion engine with oxygen sensors provided respectively upstream and downstream of an exhaust purification catalytic converter, the air-fuel ratio is feedback controlled based on an output of the second oxygen sensor only. When in this control situation, an output period of the first oxygen sensor becomes longer than that of the second oxygen sensor, response deterioration of the first oxygen sensor is judged to have occurred. Once the occurrence of response deterioration is determined, a proportional operating amount used in a proportional control of an air-fuel ratio feedback correction coefficient LMD for air-fuel ratio feedback control using the first oxygen sensor, is corrected in proportion to the response deterioration to thereby correct a deviation of the air-fuel ratio control point.

Abstract: In a diagnosing apparatus and method for an internal combustion engine having a variable valve timing control system, the apparatus and method diagnose whether the variable valve timing control system actually switches the valve timings according to a switching between an operation and non-operation of the variable valve timing control system, utilizing a variation occurrence in an intake air pulsation in response to the switching between an operation mode and non-operation mode of the variable valve timing control system.

Abstract: An air-fuel ratio control system for an internal combustion engine equipped with a three-way catalytic converter has first and second oxygen sensors disposed respectively upstream and downstream of the catalytic converter. An air-fuel ratio feedback correction coefficient is set in accordance with the output of the first oxygen sensor under a proportional plus integral control. The system has a control unit with a function to set a retard time in which the timing of a proportional control of air-fuel ratio control is compulsorily retarded, in accordance with the output of the second oxygen sensor. The retard time is limited within a range not longer than a maximum value set as a predetermined rate of an output cycle of the first oxygen sensor.

Abstract: With an air-fuel ratio control apparatus for an internal combustion engine wherein oxygen sensors are respectively arranged upstream and downstream of an exhaust gas purification catalytic converter, air-fuel ratio feedback control is carried out for diagnosis using only the downstream oxygen sensor. When during diagnostic air-fuel ratio feedback control, phase differences of output fluctuations of the two oxygen sensors are below a predetermined value, deterioration of the catalytic converter is judged. A judgment level is variably set based on the results of the deterioration diagnosis of the catalytic converter, and deterioration of response of the downstream oxygen sensor is diagnosed by comparing the output-period of the downstream oxygen sensor with the set judgment level.

Abstract: Air-fuel ratio learning is only carried out at the time of high exhaust temperatures, and is inhibited when the exhaust temperature is less than or equal to a predetermined temperature. In the latter case, air-fuel ratio feedback correction coefficient .alpha. is correctingly set, taking a correction level indicated by an air-fuel ratio learned correction coefficient K learned at the time of high exhaust temperatures as a true correction requirement level.

Abstract: With a V type engine, the exhaust air-fuel ratio is detected for each bank, and is also detected downstream of a catalytic converter which takes the combined exhaust flow from each bank. An air-fuel ratio feedback correction coefficient .alpha. is proportional-plus-integral controlled separately for each of the banks based on the air-fuel ratio detected for each of the banks, while a correction value PHOS for a proportional portion is set commonly for each of the banks, based on the air-fuel ratio detected downstream of the catalytic converter. Here the correction value PHOS is converted to separate correction values PHOSR, PHOSL for each of the banks corresponding to a change rate of the air-fuel ratio feedback correction coefficient .alpha. to an initial value, and the proportional operating amount of the proportional-plus-integral control which is carried out separately for each bank, is corrected based on the converted correction values PHOSR, PHOSL.

Abstract: An air-fuel ratio control system for an internal combustion engine comprises a catalytic converter disposed in an exhaust line of the engine. The converter has an oxygen storage effect. First and second oxygen sensors are disposed in the exhaust line at positions upstream and downstream of the converter respectively. Each sensor varies the output in accordance the oxygen concentration in the exhaust gas flowing in the exhaust line. A first device is employed for deriving an air-fuel ratio feedback correction value in accordance with the output from the first oxygen sensor. A second device is employed for changing the air-fuel ratio feedback correction value of the first device in accordance with the output from the second oxygen sensor. A third device is employed for controlling the quantity of fuel fed to the engine in accordance with the air-fuel ratio feedback correction value derived by the first device.

Abstract: An oxygen gas concentration-detecting apparatus for use in an internal combustion engine comprising a plate-shaped substrate, a plate-shaped oxygen ion-conducting solid electrode for generating an electromotive force between a first surface contacted with air and a second surface contacted with an exhaust gas of the engine according to the difference between the concentrations of oxygen gases of the air and the exhaust gas, the solid electrode being laminated on the substrate, a pair of electrode members for taking out the electromotive force as a detection signal and a nitrogen oxide-reducing catalyst layer for promoting the reduction of nitrogen oxide arranged to cover the second surface of the oxygen ion-conducting solid electrode. By this apparatus, the concentration of oxygen gas inclusive of oxygen gas generated by reduction of nitrogen oxides can be precisely detected.

Abstract: An oxygen gas concentration-detecting apparatus in an internal combustion engine using an alcohol fuel includes a ceramic substrate having one surface falling in contact with a reference gas and the other surface falling in contact with an exhaust gas of the engine and generating an electromotive force according to oxygen gas concentrations of both the gases. A pair of electrode members are arranged on the ceramic substrate to take out the electromotive force. A first oxidation catalyst layer is formed on the outer surface of the ceramic substrate to promote oxidation reaction of unburnt components. A laminate of a protecting layer of a metal oxide and a reduction catalyst layer of promoting reduction reaction of nitrogen oxides is formed on the outer surface of the first oxidation catalyst layer, and a second oxidation catalyst layer is arranged on the outer side face of the laminate to promote oxidation reaction of hydrogen gas.

Abstract: A quartz glass crucible adapted for use in a process for pulling a single crystal semiconductor material having an opaque outer substrate of a quartz glass with a relatively high bubble content and an inner transparent glass layer which is substantially free from bubbles. The crucible is produced while the substrate is supported by a rotating mould by forming an atmosphere of high temperature gas and supplying a metered quantity of powders of quartz to the high temperature gas atmosphere to have the quartz powders molten at least partly and directed toward an inner surface of the substrate to be adhered thereon.

Abstract: A quartz glass crucible adapted for use in a process for pulling a single crystal semiconductor material having an opaque outer substrate of a quartz glass with a relatively high bubble content and an inner transparent glass layer which is substantially free from bubbles. The crucible is produced while the substrate is supported by a rotating mould by forming an atmosphere of high temperature gas and supplying a metered quantity of powders of quartz to the high temperature gas atmosphere to have the quartz powders molten at least partly and directed toward an inner surface of the substrate to be adhered thereon.

Abstract: An electronic air-fuel ratio control apparatus in an internal combustion engine provided with an oxygen sensor emitting an output voltage in response to an oxygen concentration including the same in nitrogen oxides in an exhaust gas from the engine which controls an air-fuel ratio of an air-fuel mixture by a feedback correction-control based on a oxygen sensor having the nitrogen oxides-reducing catalytic layer, the detection of a theoretical air-fuel ratio is performed on a richer side comparing with the output on the detection of a theoretical air-fuel ratio by an oxygen sensor without the nitrogen oxides-reducing function and is not changed even though the nitrogen oxides concentration changes. Accordingly the feedback air-fuel ratio control operates to decrease the amount of nitrogen oxides and to stabilize the air-fuel ratio control.

Abstract: An electronic air-fuel ratio control apparatus in an internal combustion engine provided with an oxygen sensor emitting an output voltage in response to an oxygen concentration including the oxygen in nitrogen oxides in an exhaust gas from the engine. The apparatus controls the air-fuel ratio of an air-fuel mixture by a feedback correction-control based on a fuel injection quantity in an on-off manner. By using an oxygen sensor having a nitrogen oxides-reducing catalytic layer, the detection of a theoretical air-fuel ratio is performed on a richer side compared to the output on the detection of a theoretical air-fuel ratio by an oxygen sensor without the nitrogen oxides-reducing function, and is not changed even through the nitrogen oxides concentration changes. Accordingly, the feedback air-fuel ratio control acts to decrease the amount of nitrogen oxides so as to stabilixe the air-fuel ratio control.

Abstract: An air-fuel ratio control apparatus in an internal combustion engine with air-fuel ratio feedback control means comprises first air-fuel ratio sensor which senses the air-fuel ratio of the air-fuel mixture having a first level of the theoretical air-fuel ratio or leaner than the theoretical air-fuel ratio and second air-fuel ratio sensor which senses the air-fuel ratio of the air-fuel mixture having second level of the air-fuel ratio richer than the first air-fuel ratio. In a region where the amount of NO.sub.x generated is small, the first air-fuel feed back control is performed based on the detection by the first air-fuel ratio sensor, while in a region where the amount of NO.sub.x generated is large, the second air-fuel feedback control is performed based on the detection by the second air-fuel ratio sensor, whereby the amount of NO.sub.x is reduced without using an EGR control system.

Abstract: Disclosed is an oxygen gas concentration-detecting apparatus comprising a ceramic substrate for generating an electromotive force according to oxygen gas concentration of gases contacted with both the surfaces of the ceramic substrate, a pair of electrode members arranged on the ceramic substrate to take out the electromotive force, an oxidation catalyst layer formed on the outer surface of the ceramic substrate to promote oxidation reaction of unburnt components and a reduction catalyst layer arranged on the outer surface of the ceramic substrate to promote reduction reaction of nitrogen oxides. By this apparatus, the concentration of oxygen gas inclusive of oxygen gas generated by reduction of nitrogen oxides can be precisely detected, and discharge of nitrogen dioxides is controlled and a so-called EGR control device can be omitted.