Ngk Spark Plug Company, Limited

Noriaki Kondo

Shigeru Miyata

Hiroshi Inagaki

Takao Kojima

Masahiko Yamada

Hiroyuki Ishiguro

Masaru Yamano

Toshiki Sawada

Masaru Kondou

Akio Takami

Yasushi Sakakura

Toshitaka Matsuura

Katsuki Aoi

Mineji Nasu

Ken Minoha

Kazuo Taguchi

Akio Mizutani

Hiroyuki Kuno

Toshifumi Sekiya

Hirosi Inagaki

A knock sensorfor attachment to an internal combustion engine. The knock sensorincludes a capand a support member. At least a part of the top surface of the support memberis covered by capto prevent a mounting boltfrom directly making contact with the top surface of the support memberwhen the mounting boltextends through a through-holein the sensor. The capcovers the top surface of the support memberto protect the support member from being ground or abraded by the mounting bolt

Knock sensor

Apparatus for detecting the NOx concentration includes a first measurement chambercommunicating with the gas under measurement via a diffusion rate defining layerand a second measurement chambercommunicating with the first measurement chambervia diffusion limiting layers. A first pump current IPis controlled so that an output of a Vs cellwill be equal to the reference voltage VCO for controlling the oxygen concentration in the first measurement chamberto a pre-set low value. A constant voltage is applied across the second pump cellfor decomposing the NOx component in the second measurement chamberfor pumping out oxygen for detecting the NOx concentration from a second pump current IP. The sensor temperature is detected from the internal resistance of the Vs cell for controlling the current supplied to the heaters. If the temperature of the gas under measurement is changed rapidly, the sensor temperature is changed. The detected second pump current IPis corrected depending on an offset of the detected sensor temperature from the target temperature assuring detection of the NOx concentration to high accuracy.

Apparatus for detecting concentration of nitrogen oxide

Apparatus for detecting the NOx concentration includes a first measurement chamber communicating with the gas under measurement via a diffusion rate defining layer and a second measurement chamber communicating with the first measurement chamber via diffusion limiting layers A first pump current IP is controlled so that an output of a Vs cell will be equal to the reference voltage VCO for controlling the oxygen concentration in the first measurement chamber to a pre-set low value. A constant voltage is applied across the second pump cell for decomposing the NOx component in the second measurement chamber for pumping out oxygen for detecting the NOx concentration from a second pump current IP The sensor temperature is detected from the internal resistance of the Vs cell for controlling the current supplied to the heaters If the temperature of the gas under measurement is changed rapidly, the sensor temperature is changed. The detected second pump current IP is corrected depending on an offset of the detected sensor temperature from the target temperature assuring detection of the NOx concentration to high accuracy.

A method of controlling a direct fuel injection engine is provided. In the method, under a condition where an ignition timing which is accurately detectable is constant, a fuel injection timing is advanced and delayed to measure an average ion current, and the fuel injection timing is controlled so as to maximize the average ion current. Even when the efficiency of a solenoid is lowered to cause a variation of the fuel injection timing, the fuel injection timing can be controlled to be optimized, thus making it possible to maintain an intended efficiency of the direct fuel injection engine over a long period of usage. Particularly, the method can be realized by the use of a conventional ion current detecting device for detection of a misfire, it can be executed with an apparatus which can be attained at low cost. A direct fuel injection engine control system and a storage medium storing the control method of this invention are also provided.

Method of controlling a direct fuel injection engine and storage medium storing the same

A connector for an NOx sensor is connected via a cable C to an end of a sensor body through which a first pump current and a second pump current flow according to the concentration of oxygen and that of NOx, respectively, contained in a gas to be measured. The connector is provided with not only terminals for inputting a signal to and outputting a signal from the sensor body but also a label resistor RL having resistance corresponding to characteristics (relationship between oxygen concentration and first pump current and that between NOx concentration and second pump current) of the sensor body and label signal output terminals T and T connected to opposite ends of the label resistor RL. On the basis of characteristics of the sensor body , which are identified from the resistance of the label resistor RL which, in turn, is identified via the terminals T and T , the oxygen concentration and the NOx concentration are accurately obtained from detected values of the first and second pump currents. This enables an NOx sensor to always perform accurate measurement irrespective of variations in characteristics among NOx sensors.

Connector for NOx sensor

A method and apparatus for detecting a functional condition of an NOx occlusion catalyst using an NOx sensor. In order to compensate for variations in oxygen concentration of the exhaust gas which would otherwise affect the detected NOx concentration downstream of the NOx occlusion catalyst, a relative value is calculated as the difference between the detected NOx concentration and the value of the detected NOx concentration initially after start of operation control of an internal combustion engine at a lean air-fuel ratio. The occlusion capability of the NOx occlusion catalyst is judged to have deteriorated when an increase in the relative value exceeds a predetermined value. On the other hand, the NOx occlusion catalyst is judged to have suffered an anomaly when the rate of increase in the relative value becomes greater than a predetermined allowable value.

Method and apparatus for detecting a functional condition on an NOx occlusion catalyst

An ion current detection apparatus which can detect ion current with a high degree of accuracy regardless of the presence of voltage damped oscillation and which does not cause contamination of a spark plug. A spark discharge current Isp generated upon spark discharge of a spark plug,flows through a charge diode,a capacitor,and a diode,which form a closed loop together with the spark plug,and a secondary winding L,of an ignition coil,that constitutes an ignition apparatus. As a result, a Zener diode,connected in parallel to these components generates a Zener voltage Vz and thereby charges the capacitor,When a preset wait time has elapsed after the ignition timing for starting spark discharge, the discharge switch,short-circuits the opposite ends of the charge diode,to discharge the capacitor,so that a high voltage having a polarity opposite that in the case of spark discharge is applied to the spark plug. An ion current Iio flowing at this time is detected by use of a resistor,connected in parallel to the diode

Ion current detection apparatus

Using a sole Nox sensor Nox concentration and oxygen concentration are measured accurately. A measurement device for measuring NOx concentration and oxygen concentration comprises an NOx sensor,having a first measurement chamber,communicating via a diffusion rate regulating layer,with the gas under measurement and a second measurement chamber,communicating with the first measurement chamber,via diffusion rate regulating layers,. A first pump cell,and an oxygen concentration measurement Vs cell,are formed on the first measurement chamber,, while a second pump cell,is formed on the second measurement chamber,. Inside of the first measurement chamber,is controlled to a constant low oxygen concentration by controlling the first pump current IP,so that output of Vs cell,will equal a reference voltage VC,. By applying a constant voltage across the second pump cell,NOx in the second measurement chamber,is decomposed to pump out oxygen. Thus NOx concentration and oxygen concentration are measured from the second pump current IP,and from the first pump current IP,, respectively. During measurement, sensor temperature is detected from the internal resistance of the Vs cell for controlling heater current supplied to heaters,to maintain a constant sensor temperature.

Method and apparatus for measuring oxygen concentration and nitrogen oxide concentration

An NOx-concentration detecting apparatus is disclosed which enables a user to readily know a record of operating conditions of an NOx sensor. The apparatus includes an NOx sensor, pumping-current control means, constant-voltage application means, NOx-concentration detecting means, a heater and writing means for writing to a recorder variation of at least one parameter selected from a first pumping current value, a second pumping current value, the concentration of oxygen contained in the measurement gas and the concentration of NOx in the measurement gas. Also disclosed is an NOx-concentration detecting apparatus capable of determining the concentration of NOx at a high resolution even when different NOx sensors are used. The NOx-concentration detecting apparatus detects the first pumping current I.sub.P1, and the second pumping current I.sub.p2, corrects the detected values based on correction data stored on a floppy disk, and determines the concentration of NOx in the measurement gas using standard characteristics stored in ROM of the ECU, namely, characteristics representing correlations among the first pumping current I.sub.P1, the second pumping current I.sub.p2 and the concentration of NOx in the measurement gas. The correction data are used for making previously measured characteristics of the NOx sensor equal to the standard characteristics, which characteristics represent correlations among the first pumping current I.sub.P1, the second pumping current I.sub.p2 and the concentration of NOx in the measurement gas. Accordingly, when the concentration of NOx in the same measurement gas is measured using different NOx sensors, any of the NOx sensors can provide an accurate measurement.

NOx-concentration detecting apparatus

An air/fuel ratio detection device and an air/fuel ratio control device, in which combustion of an engine is controlled with a simple design and toxic substances in exhaust gas discharged from the engine are reduced. Time A during which a lean signal is at a high level is measured. If the time A is shorter than the predetermined value, it is determined that the air/fuel ratio is richer than a target value, and time B during which an electromagnetic valve 21 is open is lengthened, increasing the quantity of supply air and making leaner the fuel mixed air, such that the target air/fuel ratio is approached. If the time A is longer than the predetermined value, it is determined that the air/fuel ratio is leaner and the time B is shortened.

Air/fuel ratio detection device and an air/fuel ratio control device

An air/fuel ratio sensor is controlled such that the oxygen concentration of the measurement gas can be detected from a pump current substantially instantaneously after a heater turns on. In the air/fuel ratio sensor an oxygen pumping cell and an oxygen concentration measuring cell are each formed of a solid electrolytic layer interposed between a pair of porous electrodes. One of the electrodes of each cell defines a measurement gas chamber in which the diffusion of the measurement gas is controlled. After a micro current is supplied to the other electrode of the oxygen concentration measuring cell for a predetermined period of time, thereby forming an internal reference oxygen source, the supply of the micro current is stopped and at the same time a pump current in the oxygen pumping cell starts to be controlled until the interelectrode voltage of the oxygen concentration measuring cell reaches a target voltage. After the air/fuel ratio sensor is activated, the supply of the micro current is restarted.

Method and a device for controlling an air/fuel ratio sensor

Oxygen sensor element (ZrO.sub.2 solid electrolyte etc) for detecting oxygen concentration in an exhaust gas has a protective layer which is made of a heat-resistant metal oxide and which carries a component of a IIa subgroup element (Ca, Mg etc) on the side exposed to the exhaust gas of the sensor element, at least a part of the protective layer being present as a nonstoichiometric compound (Ti oxide etc) with respect to the heat-resistant metal oxide. Si-poisoning is prevented. Heater for heating the sensor element is provided for preventing Si-poisoning at low temperatures.

Oxygen sensor for preventing silicon poisoning

A misfire detecting device for an ignition system, comprises high voltage applying means for applying a pulsed high voltage to each spark plug of an engine after completion of firing of the spark plug, voltage restricting means for restricting a peak of the pulsed high voltage to a highest possible value that does not cause firing of the spark plug, voltage detecting means for detecting a plug voltage across a center electrode-to-outer electrode of the spark plug after reducing the same, and misfire detecting means for detecting a misfire at each cylinder on the basis of a decay characteristic of a detection voltage which is caused by application of the pulsed high voltage. In another embodiment, the misfire detecting device comprises high voltage applying means which monitors a detection voltage which is caused by application of the pulsed high voltage to each spark plug and controls the pulsed high voltage so that the detection voltage is maintained at a highest possible value that does not cause firing of the spark plug due to application of the pulsed high voltage to the spark plug.

Misfire detecting device

A misfire detecting device for a multi-cylinder internal combustion engine is provided. The misfire detecting device comprises high voltage pulse producing means for producing, after spark discharge of a spark plug, a high voltage pulse which is not so high as to cause the spark plug to discharge, voltage applying means for applying the high voltage pulse to a conductive path connecting between the secondary winding of the ignition coil to the spark plug, by way of a reverse current preventing diode and a leakage preventing diode for preventing intrusion of the high voltage for ignition, voltage dividing means for dividing a voltage at the junction between the reverse current preventing diode and the leakage preventing diode to obtain a divided voltage thereat, and misfire detecting means for detecting a misfire on the basis of a decay characteristic of the divided voltage obtained after application of the high voltage pulse. The high voltage pulse producing means, the voltage applying means, the voltage dividing means and the combustion condition detecting means are housed within a case having a pair of terminals connectable directly and in series to the conductive path and having disposed therewithin a conductive line connecting between the terminals. The voltage applying means applies the high voltage pulse to the conductive line.

Growing community of inventors

Aichi, Japan

Noriaki Kondo