Ngk Spark Plug Company, Limited

Tomonori Uemura

Yuzo Higuchi

Hiroshi Inagaki

Norikazu Ieda

Satoshi Teramoto

Yoshinori Inoue

Katsunori Yazawa

Tetsuya Ito

Kaoru Hisada

Satoru Abe

Chihiro Tomimatsu

Junichiro Mitsuno

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

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.

Sensor control apparatus and gas detection system

A gas concentration detection device for detecting a gas concentration using a limiting current type gas concentration sensor. In an application voltage line set to pass through a plurality of limiting current regions for different values of gas concentration, a ratio for lean is set as a ratio of change in current with respect to a change in voltage when an air/fuel ratio corresponding to the gas concentration is lean, and a ratio of rich different from the ratio for lean is set when the air/fuel ratio is rich.

Gas concentration detection device

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

In a heather control apparatus for a gas sensor, a CPU obtains upper and lower limit values by adding a predetermined value to and subtracting the predetermined value from an Rpvs average obtained in a last heater energization period (or to an Rpvs value obtained for the first time), and sets a window W. The CPU obtains a plurality of Rpvs values [P] to [P], and obtains an Rpvs average Awhile excluding Rpvs values [P], [P], and [P] which do not fall within the window W(not less than the lower limit value and not greater than the upper limit value). The CPU obtains the upper and lower limit values by adding the predetermined value to and subtracting the predetermined value from the Rpvs average A, and sets a window Wfor the next heater energization period.

Heater control apparatus for gas sensor

An in-vehicle sensor () mounted on a vehicle VE and connected to a communication bus CAN including a bus connection connector () for connection to the CAN and external terminals (T, T) for communication, and one or a plurality of external terminals (T, T) for setting each brought into either of a first connection state not connected to any potential and a second connection state connected to a ground potential GND; a judgment section S-S, S-Sfor setting whether the connection state is the first connection state or the second connection state; and an identifier setting section Swhich sets an identifier ID of the in-vehicle sensor () used on the communication bus CAN based on the judged connection state(s) for setting of the one or plurality of external terminals (T, T).

In-vehicle sensor and in-vehicle sensor system

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.

An in-vehicle sensor () connected to a communication bus CAN includes a bus connection connector () including external communication terminals T, T, and external setting terminals T, Teach of which is brought into one of a plurality of connection states; judgment means S-Sfor judging the connection states of the external terminals for setting T, Twhen electric power is supplied in a state in which the bus connection connector () is connected to the communication bus CAN; identifier generation means Sfor generating an identifier ID of the in-vehicle sensor () based on the judged connection states; a nonvolatile storage section () for storing the identifier ID; communication means () for performing communications through the communication bus CAN using the stored identifier ID; and storing means Sfor storing a first generated initial identifier IDS in the storage section () as the identifier ID.

In-vehicle sensor, in-vehicle sensor system, and method of setting identifiers of in-vehicle sensors in in-vehicle sensor system

A sensor temperature control apparatus () includes switching device (); energization control means Sand Sfor controlling duty ratio DT to maintain sensor element section () at a target temperature; storage means () for storing a first duty ratio DTin advance; element temperature judgment means Sfor determining whether the temperature of the sensor element section falls within a first temperature range including the target temperature; and semi-shorted state detection means Sto Sfor comparing a present duty ratio DTwith the first duty ratio in a state in which the temperature of the sensor element section falls within the first temperature range, to thereby determine whether a semi-shorted first temperature range state has arisen in which only a portion of the current flowing through switching device flows through heater section () and the temperature of the sensor element section falls within the first temperature range.

Sensor temperature control apparatus

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 heater control apparatus (1) includes a heater driver () which is turned on and off in accordance with a pulse drive signal PS, heater energization control means SSfor outputting the pulse drive signal PS to the heater driverso as to control the supply of electric current to the heater section (4), power supply voltage detection means SSfor detecting a power supply voltage VB of the power supply BT, ideal electric energy obtaining means SSfor obtaining an unit ideal electric energy WAi, actual electric energy calculation means Sfor calculating an unit actual electric energy WA, and duty ratio determination means Sfor determining a duty ratio DT(n+1) of the pulse drive signal PS such that the unit actual electric energy WA(n+1) becomes equal to the unit ideal electric energy WAi(n+1) in the next period T(n+1).

Heater control apparatus and sensor control system

A gas sensor control apparatus () for controlling a gas sensor () includes a change amount detection means (); an element resistance detection means for detecting the element resistance Rpvs of a sensor element section () on the basis of the response change amount &#x394;Vs; a heater energization control section for on-off controlling the supply of electric current to a heater section () by pluses PS having a fixed period T; and an instruction signal output section for instructing the change amount detection section () to detect the response change amount &#x394;Vs at a third timing twhich comes after elapse of a predetermined wait time TW from a second timing t(heater energization off) which changes in accordance with the pulse width PSW.

Gas sensor control apparatus

A control device for a gas sensor is configured to: receive a mode command to specify one of a plurality of sensor energization modes including at least a gas concentration detection mode, a protection mode and a pre-energization mode; switch a sensor element of the gas sensor into the one of the plurality of sensor energization modes according to the mode command; judge satisfaction of a certain condition where the mode command is to specify the gas concentration detection mode and the sensor element is in any of the plurality of sensor energization modes other than the pre-energization mode at the time of receipt of the mode command; and prohibit the sensor element from switching over to the gas concentration detection mode when the certain condition is satisfied.

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Komaki, Japan

Tomonori Uemura