Ngk Spark Plug Company, Limited

Honda Giken Kogyo K.k.

Shigeru Miyata

Yoshihiro Matsubara

Noriaki Kondo

Yasuo Ito

Hideji Yoshida

Hiroshi Inagaki

Yoshitaka Yamada

Takashi Suzuki

Junichi Kagawa

Kiyotaka Ohno

Takafumi Oshima

Noboru Ishida

Takao Kojima

Nobuhiro Hayakawa

Takashi Hisaki

Masashi Ando

Yoshiaki Matsubara

Kazunori Yokota

Yuuichi Shimasaki

Toshiki Sawada

Masaru Kondou

Tetsusho Yamada

Hirosi Inagaki

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 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 NO,sensor capable of accurately determining the concentration of NO,contained in a gas to be analyzed (measurement gas) using a simple circuit. The NO,sensor includes a first measurement space and a second measurement space. The first measurement space communicates with the measurement gas via a first diffusion controlling layer, and the second measurement space communicates with the first measurement space via a second diffusion controlling layer. A first pumping current I,is controlled such that an output from a Vs cell is used as a reference voltage V,to control the amount of oxygen flowing into the second measurement space at a constant level. A constant voltage is applied to the second pumping cell so as to decompose the NO,component of the measurement gas contained in the second measurement space, and to pump out the resulting oxygen from the second measurement space. Accordingly, the concentration of NO,contained in the measurement gas can be obtained from second pumping current I,. The electrode of the Vs cell located on the side of the first measurement space is formed around the periphery of or on a portion of the diffusion controlling layer of the Vs cell. As a result, the amount of oxygen flowing from the first measurement space into the second measurement space can be accurately determined by means of the Vs cell. Also, the NO,concentration can be accurately determined without the need for compensation.

NOx sensor

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 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

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 method of detecting a misfire of an ignition system for an internal combustion engine is provided. By the method, after completion of spark discharge of a spark plug, a high tension pulse which is not so high as to cause spark discharge is applied to each spark plug by way of a reverse current preventing diode and a secondary winding of an ignition coil or by way of a reverse current preventing diode and a leakage preventing diode for preventing ingress of an ignition high voltage. Misfire at each cylinder is detected on the basis of a voltage attenuation characteristic at a passing side terminal of the reverse current preventing diode. A device for carrying out the above method is also provided.

Method of detecting misfire of engine ignition system and device for

A misfire detecting device for an ignition system, comprises high voltage applying device for applying a pulsed high voltage to each spark plug of an engine after completion of firing of the spark plug, voltage restricting device 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 component for detecting a plug voltage across a center electrode-to-outer electrode of the spark plug after reducing the same, and misfire detecting device 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 has a high voltage device 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.

In a spark plug voltage probe device which detects a voltage applied to a spark plug installed in an internal combustion engine so as to analyze a burning condition in the internal combustion engine on the basis of the voltage applied to the spark plug, a rubber clamper (9) is secured to the internal combustion engine, and having a groove (92) in which a spark cable (60) is located so as to form a static capacity between the rubber clamper (9) and the spark plug cable (60). An electrical conductor (93) is embedded in the rubber clamper (9) along the groove (92) while the electrical conductor (93) is connected to a microcomputer by way of an output cable (64) so as to analyze a spark plug voltage waveform. A condenser (42) is connected to a common point (A) between the electrical conductor (93) and the microcomputer so as to reduce the spark plug voltage according to a capacity of the condenser (42).

Spark plug voltage probe device in an internal combustion engine

In a sparkplug voltage probe device in use for an internal combustion engine, an insulator base is attached to the internal combustion engine, an upper surface of the insulator base having a plurality of grooves in which the sparkplug cables are placed. An insulator sheet is embedded in the insulator base. An electrode layer is provided on an upper surface of the insulator base along the grooves to form a static capacity between the electrode layer and the sparkplug cables when the voltage is applied across the spark plugs. On a lower surface of the insulator sheet an electrical shield layer is provided connected to the internal combustion engine by a ground wire. A lead wire electrically connects the electrode plate to a microcomputer so as to analyze the engine burning condition based on the static capacity between the electrode plate and the sparkplug cables.

Sparkplug voltage probe for use with an internal combustion engine by

A misfire detecting device for a double-ended distributorless ignition system is provided. The device includes a pulse generating circuit for generating a positive polarity pulse which is not so high as to cause spark discharge during the time after completion of spark discharge and before beginning of application of an ignition high voltage for next spark discharge. A reverse current preventing diode is connected at an anode to an output end of the pulse generating circuit and at a cathode to a positive polarity side of a secondary winding of an ignition coil. A plug voltage dividing circuit for dividing a plug voltage is connected between a center electrode and an outer or ground electrode of each of spark plugs to obtain a divided voltage. A detecting circuit detects a misfire of the spark plugs on the basis of an attenuation characteristic of the divided voltage after application of the positive polarity pulse.

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Nagoya, Japan

Shigeru Miyata