Ngk Spark Plug Company, Limited

Ngk Spark Plus Co., Ltd.

Yuzo Higuchi

Tomonori Uemura

Yoshinori Tsujimura

Takio Kojima

Toshiyuki Matsuoka

Hiroshi Inagaki

Satoru Abe

Koji Ishibashi

Takashi Mori

Takuya Mizuno

A sensor control apparatus includes a current control section, a first condition judgment section, a second condition judgment section, a deterioration detection energization section, and a deterioration voltage detection section. The current control section controls pump current such that electromotive force cell voltage becomes equal to a control target voltage. The first condition judgment section judges whether or not a first deterioration detection condition is satisfied. The second condition judgment section judges whether or not a second deterioration detection condition is satisfied when the first deterioration detection condition is satisfied. The deterioration detection energization section supplies deterioration detection current to the oxygen concentration detection cell when the second deterioration detection condition is satisfied. The deterioration voltage detection section detects a deterioration detection voltage generated in the oxygen concentration detection cell after a deterioration detection time following the supply of the deterioration detection current has been started.

Sensor control apparatus

A sensor element drive circuit is a circuit including a plurality of semiconductor elements formed on a semiconductor substrate for realizing a current control function and a switching function. The current control function is a function of controlling the current flowing between electrodes such that the potential difference between electrodes becomes constant. The switching function is a function for switching between a connected state in which the electrodes are electrically connected to a sensor control apparatus and a cut-off state in which electrical continuity therebetween is broken. When one of an Ip+ terminal, a COM terminal, and a Vs+ terminal is determined to have an anomalous potential, the sensor control apparatus causes the sensor element drive circuit to perform switching from the connected state to the cut-off state, and connects the semiconductor substrate to a negative voltage lower than a ground potential applied to the sensor element drive circuit.

A voltage supply apparatus for supplying a voltage to a detection circuit, including a power supply filter () and a control section () which supply a sensor drive voltage Vbg to a sensor device () having a ratiometric characteristic. The power supply filter () has supply paths PLand PL. The control section () determines whether or not a switching determination time has elapsed after startup. In the case where the switching determination time has not yet elapsed, the power supply filter () supplies the sensor drive voltage Vbg through supply path PL. In the case where the switching determination time has elapsed, the power supply filter () supplies the sensor drive voltage Vbg through supply path PL. The response of the sensor drive voltage Vbg to a variation in power supply voltage Vcc is slower when supplied through the supply path PLthan through the supply path PL

Voltage supply apparatus

A sensor control apparatus controls a gas sensor which measures the concentration of oxygen contained in exhaust gas. A current DA converter of the sensor control apparatus supplies a current having a current value designated by a control section (hereinafter referred to as the designated current value) to a label resistor having a resistance previously set so as to represent the characteristic of the gas sensor (hereinafter referred to as the characteristic resistance). Further, the control section of the sensor control apparatus sets the designated current value to a plurality of values in accordance with the characteristic resistance of the label resistor.

Sensor control apparatus and sensor control system

A gas sensor system () including a gas sensor () and a sensor control section () including detection circuits (), () and () for detecting the terminal potentials V, V, and Vof first to third terminal Tthrough T. The sensor control section () includes a circuit () for applying an examination potential Vex to the second terminal T, a first circuit () which has a predetermined resistance Rand disconnectably connects the first terminal Tand the second terminal T, a second circuit () which has a predetermined resistance Rand disconnectably connects the second terminal Tand the third terminal T, and terminal potential detection means Sfor detecting the terminal potentials V, V, and Vusing the detection circuits in a state in which the examination potential Vex is applied to the second terminal Tand switches SWand SWare turned on.

Gas sensor system

A sensor control apparatus controls a gas sensor including an electromotive force cell (a detection cell) and an oxygen pump cell. The sensor control apparatus includes an AD conversion section (); a PID computation section (); a first signal generation section () which generates a DAC control signal S(a pump current control signal) based on the results of PID performed by the PID computation section (); a current DA conversion section (); and a first signal generation section (), a second signal generation section (), and a signal output section () configured to selectively set a combination of the results of the computations performed by the PID computation section () and to generate a gas detection signal Sbased on the set combination of the computation results.

Sensor control apparatus and gas detection system

In a sensor control apparatus of a gas detection system, a multiplexer having received an instruction from a digital computation section outputs analog signals in the order of, for example, 'signal, signal, signal, signal, signal, signal.' By outputting the analog signals while classifying each of them as a high occurrence-frequency signal which is high in output frequency or a low occurrence-frequency signal which is low in output frequency, the multiplexer can increase the sampling frequency of signal (analog signal of Vs+-COM voltage) which is the high occurrence-frequency signal. The sensor control apparatus can increase the sampling frequency in AD conversion of signal to a digital value, while suppressing an increase in the cost of an AD conversion section.

A sensor control apparatus of a gas detection system includes a digital computation section having a PID computation section, a first filter section, and a second filter section as functional sections. The first filter section digitally extracts a DAC control signal (first filter signal) from a digital signal representing a supply control current Tip computed by the PID computation section. The DAC control signal is a digital signal which represents the supply control current Tip for pump current and in which noise components superimposed as a result of digital computation in the PID computation section have been attenuated.

A gas sensor system () includes a gas sensor () having a cell () electrically communicating with a first terminal Tand a second terminal T, and a cell () electrically communicating with Tand a third terminal T; and a sensor control section () including detection circuits () for detecting the terminal potentials V, V. The sensor control section includes circuit () for bringing Tto an examination potential Vex; constant current circuits () for supplying examination currents Ipoc, Icp; terminal potential detection means Sfor detecting V, Vbefore the gas sensor detects the gas concentration in an activated state, and in a state in which Tis brought to examination potential Vex and Ipoc, Icp are supplied to the cells (); and wire breakage determination means S, Sfor determining a wire breakage anomaly and its location based on the V, V

When a voltage applied to a heater assumes a low-level potential, a control section of a load drive apparatus instantaneously supplies an anomaly judgment current to the heater, and computes the electrical resistance of the heater on the basis of the anomaly judgment current. The control section judges whether or not any of anomalous states of the heater, including at least a deteriorated state of the heater and wiring anomalous states of the heater, has occurred on the basis of the electrical resistance of the heater.

Load drive apparatus

A sensor control apparatus controls a gas sensor by means of digital control and restrains a decrease in accuracy of pump current control. A gas detection system includes such a sensor control apparatus. The sensor control apparatus includes a reference voltage generation section, and can change the maximum current range of pump current Ip in the current DA conversion section. The sensor control apparatus can set the maximum current range of the pump current Ip to a proper range in accordance with the type or characteristic of a gas sensor to be controlled. Namely, in the case where a gas sensor has a small sensor maximum current, the maximum current range of the current DA conversion section is changed to a range determined in consideration of the sensor maximum current of the gas sensor, which restrains a decrease in the accuracy in controlling the pump current Ip.

A sensor control apparatus () of a gas detection system () includes a first low-pass filter (), a second low-pass filter (), and a multiplexer () so as to provide different time constants for detection of a sensor output signal Vsand for detection of a response signal Vs. When the sensor output signal Vsis detected, a signal whose frequency band is the same as that of Vsis input to the analog-to-digital conversion section () through the first low-pass filter (). Therefore, the detection accuracy of Vsis increased. When Vsis detected, a signal whose frequency band is the same as that of Vsis input to the analog-to-digital conversion section () through the second low-pass filter ().

A sensor control apparatus which receives from a gas sensor () a sensor output signal Ip corresponding to the concentration of a specific gas component, and a pressure signal P output from a pressure sensor (). The sensor control apparatus includes a computation section () which computes a specific component concentration which is corrected based on the pressure signal P so as to eliminate the influence of the pressure of the gas. The sensor control apparatus includes response adjustment sections () and () for adjusting the response rates of the sensor output signal Ip and the pressure signal P before being input to the computation section (), the response rate exhibiting a time variation of the corresponding signal to a change in the pressure of the gas, such that the response rate of the sensor output signal Ip or the response rate of the pressure signal P, whichever is faster, approaches the slower of the two.

Sensor control apparatus, sensor control system, and sensor control method

An output correction apparatus that corrects offset drift of a cylinder internal pressure sensor, and a cylinder internal pressure detection apparatus that accurately detects cylinder internal pressure of an internal combustion engine through use of the output correction apparatus. The cylinder internal pressure detection apparatus includes a detection circuit section which detects a change in the resistance of a piezoresistor element as an electrical signal; an amplification circuit section which amplifies and outputs the electrical signal (output value); and a correction circuit section which corrects the output value. The correction circuit section includes a reset control section which resets the output value of the amplification circuit section to a reference value, and a reset timing detection section which determines a timing of the resetting.

Apparatus for correcting output of cylinder internal pressure sensor, and cylinder internal pressure detection apparatus including the same

A pressure detection apparatus has a pressure-sensitive resistor whose first resistance varies according to pressure and a change of its own temperature, a temperature-sensitive resistor which has a same resistance-temperature coefficient as the pressure-sensitive resistor and whose second resistance varies according to the change of the temperature, a current source supplying first and second constant-currents to the pressure-sensitive and temperature-sensitive resistors respectively, and a pressure signal generation output section. The current source adjusts the first and second constant-currents so that when the pressure is an initial pressure, a reference first voltage appearing across the pressure-sensitive resistor and a reference second voltage appearing across the temperature-sensitive resistor become equal to each other. The pressure signal generation output section outputs a first voltage signal corresponding to the pressure on the basis of a difference voltage between a first voltage of the pressure-sensitive resistor and a second voltage of the temperature-sensitive resistor.

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Komaki, Japan

Yuzo Higuchi