JP4898544B2 - Sensor control device - Google Patents

Description

  In the present invention, when controlling a gas sensor including a plurality of cells each having a pair of porous electrodes formed on the surface of a solid electrolyte body, the energization state in the plurality of cells is controlled in order to detect a specific gas contained in the measurement target gas. The present invention relates to a sensor control device.

2. Description of the Related Art Conventionally, a sensor control device that controls a gas sensor having a plurality of cells each having a pair of porous electrodes formed on the surface of a solid electrolyte body is known.
As an example of such a gas sensor, there are a 2-cell type oxygen sensor for detecting an oxygen concentration, a NOx sensor for detecting a concentration of nitrogen oxide (NOx) of a 3-cell type, and the like. The oxygen sensor and the NOx sensor are attached to an exhaust passage of an internal combustion engine such as an automobile engine, for example, and change in accordance with a specific gas concentration (oxygen concentration, NOx concentration) in the exhaust gas (hereinafter referred to as a sensor signal). (Also called).

  And in controlling a gas sensor, a sensor control apparatus controls the energization state in a plurality of cells suitably, in order to detect specific gas contained in measurement object gas. The sensor control device is electrically connected to a gas sensor (specifically, a cell) via a connection path such as an electric signal cable to control the energization state of each cell.

  However, if the connection path connecting the gas sensor and the sensor control device falls into an abnormal state such as disconnection or ground short (ground short circuit), the sensor control device cannot properly control the gas sensor, and normal gas detection Is impossible.

  On the other hand, a sensor control device having a function of determining a connection path abnormality has been proposed (Patent Document 1, Patent Document 2). These conventional devices input a test signal different from the detection signal input during gas detection to a cell different from the abnormality determination target cell among a plurality of cells, and determine an abnormality due to the input of the test signal. By determining whether or not the output signal of the target cell has fluctuated, abnormality of the connection path is determined.

That is, the conventional apparatus forcibly generates a situation in which the output signal of the abnormality determination target cell fluctuates by inputting a test signal different from the signal at the time of detection, and then the output signal of the abnormality determination target cell at that time If there is no fluctuation, it is determined that some abnormality (disconnection abnormality, etc.) has occurred in the connection path.
JP 2004-144733 A (Claim 3) Japanese Patent Laying-Open No. 2005-091274 (Claim 2)

  However, in the above-described conventional apparatus, when determining whether or not the connection state between the abnormality determination target cell and the sensor control apparatus is abnormal, a test signal different from the detection signal input at the time of gas detection is input. Since this is necessary, there is a problem that the gas detection operation needs to be interrupted.

  That is, during the period for determining whether or not the connection path is abnormal, the cell to which the test signal is input does not receive the detection time signal, and thus cannot operate for detecting the specific gas concentration. . As a result, when the abnormality of the connection path is determined, the gas sensor as a whole cannot detect the specific gas concentration in the measurement target gas.

  Therefore, the present invention has been made in view of these problems, and provides a technique for determining whether or not the connection state between the gas sensor and the sensor control device is abnormal without interrupting the detection operation of the specific gas concentration. For the purpose.

  The invention according to claim 1, which has been made to achieve the above object, is to specify a specific gas contained in a measurement target gas when controlling a gas sensor having a plurality of cells each having a pair of porous electrodes formed on the surface of a solid electrolyte body. A sensor control device that controls energization states in a plurality of cells in order to detect gas, and is a cell that is different from an abnormality determination target cell among the plurality of cells and causes a change in the energization state of the abnormality determination target cell With regard to the fluctuation determination reference cell whose own energization state fluctuates in relation to the fluctuation determination reference cell, whether the energization state of the fluctuation determination reference cell has fluctuated or not is determined by the energization state fluctuation determination means. When it is determined that the energization state of the reference cell has changed, and the energization state of the abnormality determination target cell has changed, the abnormality determination target cell and the sensor control device A connection state determination unit that determines that the connection state is a normal state and the connection state between the abnormality determination target cell and the sensor control device is an abnormal state when the energization state of the abnormality determination target cell does not vary; This is a sensor control device.

  First, in the case where a cell whose own energization state varies in relation to a factor that varies the energization state of the abnormality determination target cell among a plurality of cells is defined as a variation determination reference cell, the energization state of the variation determination reference cell is When it fluctuates, the energization state of the abnormality determination target cell also fluctuates accordingly.

  Therefore, the sensor control device including the above-described energization state variation determination unit determines whether or not the energization state of the abnormality determination target cell varies based on the energization state of the variation determination reference cell different from the abnormality determination target cell. Can be determined. That is, the sensor control device determines whether the abnormality determination target cell is energized based on whether or not the variation determination reference cell has been energized without inputting an abnormality detection signal to the gas sensor cell. It is possible to determine the time of fluctuation, and to predict that the energization state of the abnormality determination target cell will fluctuate.

  If the energization state of the abnormality determination target cell does not vary when the energization state of the fluctuation determination reference cell is determined to have changed by the energization state variation determination means, the energization state of the abnormality determination target cell is determined by sensor control. It can be determined that the abnormal state is not properly transmitted to the apparatus.

  That is, when it is determined that the energization state of the fluctuation determination reference cell has changed as in the above-described connection state determination means, the abnormality determination is performed by determining whether the energization state of the abnormality determination target cell has changed. It is possible to determine whether the connection state between the target cell and the sensor control device is a normal state or an abnormal state.

For this reason, a sensor control device provided with the above-mentioned connection state determination means can determine whether the connection state between the abnormality determination target cell and the sensor control device is a normal state or an abnormal state.
The sensor control device configured as described above is configured so that the connection state between the abnormality determination target cell and the sensor control device is a normal state or an abnormal state without inputting an abnormality detection signal to the gas sensor cell. Can be determined. That is, this sensor control device does not need to interrupt gas detection when determining whether the connection state between the abnormality determination target cell and the sensor control device is a normal state or an abnormal state.

  Therefore, according to the sensor control device of the present invention, it is possible to determine whether or not the connection state between the gas sensor and the sensor control device is abnormal without interrupting the detection operation of the specific gas concentration. That is, according to this sensor control device, the specific gas concentration detection operation and the abnormality determination operation of the connection state between the gas sensor and the sensor control device can be executed in parallel.

Note that examples of the “factor that changes the energization state of the abnormality determination target cell” include a change in oxygen concentration of the measurement target gas and a change in element temperature of the gas sensor.
In addition, the connection state determination unit immediately determines that the connection state between the abnormality determination target cell and the sensor control device is normal when the energization state variation determination unit determines that the energization state of the fluctuation determination reference cell has changed. Or may be determined to be abnormal. However, the fluctuation of the energization state of the abnormality determination target cell follows and fluctuates behind the fluctuation of the energization state of the fluctuation determination reference cell. In consideration of this follow-up delay time, whether or not the energization state of the abnormality determination target cell has changed after a lapse of a certain time after the energization state of the variation determination reference cell has been determined to have changed by the energization state change determination means. The connection state determination means may be configured to detect and determine whether or not the connection state between the abnormality determination target cell and the sensor control device is normal.

  In the above-described sensor control device, as described in claim 2, the energization state variation determination means includes the reference cell variation amount indicating the variation amount of the energization state in the variation determination reference cell and the energization of the variation determination reference cell. When the reference cell fluctuation amount is equal to or larger than the reference fluctuation determination value by comparing with a predetermined reference fluctuation determination value to determine that the state has changed, the energization state of the fluctuation determination reference cell has changed. If the reference cell fluctuation amount is smaller than the reference fluctuation judgment value, it can be determined that the energization state of the fluctuation judgment reference cell is not fluctuated.

In this way, by comparing the reference cell fluctuation amount with the reference fluctuation determination value, it is possible to determine whether the energization state of the fluctuation determination reference cell has changed.
As the reference cell fluctuation amount, a fluctuation amount of the interelectrode voltage or a fluctuation amount of the interelectrode current in the fluctuation determination reference cell can be used. In addition, the reference fluctuation determination value can set a fluctuation amount when the energization state of the fluctuation determination reference cell fluctuates according to the type of reference cell fluctuation amount, and is based on actual measurement data using an actual gas sensor. Can be determined.

  Further, in the above-described sensor control device, as described in claim 3, the connection state determination means includes the target cell fluctuation amount indicating the fluctuation amount of the energization state in the abnormality determination target cell and the energization state of the abnormality determination target cell. When the target cell fluctuation amount is equal to or larger than the target fluctuation determination value, the energization state of the abnormality determination target cell has changed. When the connection state between the abnormality determination target cell and the sensor control device is determined to be normal, and the target cell fluctuation amount is smaller than the target fluctuation determination value, the energization state of the abnormality determination target cell varies. It can be determined that the connection state between the abnormality determination target cell and the sensor control device is an abnormal state.

In this way, by comparing the target cell fluctuation amount with the target fluctuation determination value, it is possible to determine whether or not the energization state of the abnormality determination target cell has changed.
As the target cell fluctuation amount, a fluctuation amount of the interelectrode voltage or a fluctuation amount of the interelectrode current in the abnormality determination target cell can be used. The target fluctuation determination value can be set as the fluctuation amount when the energization state of the abnormality determination target cell fluctuates according to the type of the target cell fluctuation amount, and is based on actual measurement data using an actual gas sensor. Can be determined.

  Next, in the above-described sensor control device, as described in claim 4, it is possible to adopt a configuration in which the fluctuation determination reference cell is a temperature detection cell for detecting the temperature of the gas sensor.

  That is, since the energization state of the cell made of the solid electrolyte body has a correlation with the element temperature of the gas sensor, the energization state of the abnormality determination target cell changes when the temperature change of the gas sensor occurs. For this reason, the temperature detection cell changes its energization state in relation to the element temperature that changes the energization state of the abnormality determination target cell, and can be used as a fluctuation determination reference cell.

  For this reason, when it is determined in the energization state variation determining means that the energization state of the temperature detection cell has fluctuated, the energization state of the abnormality determination target cell varies if the connection path is in a normal state, whereas the connection state If the path is in an abnormal state, the energization state of the abnormality determination target cell does not change.

  Therefore, as in the present invention, by using the temperature detection cell as a fluctuation determination reference cell, whether or not the connection state between the gas sensor and the sensor control device is abnormal without interrupting the detection operation of the specific gas concentration. It becomes possible to judge.

  The temperature detection cell is not limited to a cell provided only for temperature detection, but may be a cell that performs other functions (for example, gas concentration detection) in addition to temperature detection.

  Next, in the above-described sensor control device, as described in claim 5, the gas sensor introduces the measurement target gas and adjusts the oxygen concentration of the measurement target gas to the target concentration to obtain the adjusted measurement target gas. A first measurement chamber for generating, and a second measurement chamber into which an adjusted measurement target gas in which the oxygen concentration is adjusted to a target concentration in the first measurement chamber is introduced. One of the pair of porous electrodes is arranged in the second measurement chamber, and an interelectrode current corresponding to the concentration of NOx as the specific component contained in the adjusted measurement target gas flows. The variation determination reference cell can take a configuration in which one of the pair of porous electrodes is disposed in the first measurement chamber.

  In the gas sensor having such a configuration, if the oxygen concentration fluctuates in the first measurement chamber, among the plurality of cells, the energization state of the cell in which one of the pair of porous electrodes is arranged in the first measurement chamber fluctuates. At the same time, the oxygen concentration of the measurement target gas after adjustment varies and the oxygen concentration in the second measurement chamber also varies. And if the oxygen concentration of a 2nd measurement chamber changes, the electricity supply state of the cell by which one of a pair of porous electrodes will be arrange | positioned in a 2nd measurement chamber among several cells will change.

  That is, in this gas sensor, if the oxygen concentration fluctuates in the first measurement chamber, the energization state of the fluctuation determination reference cell fluctuates, and the oxygen concentration of the adjusted measurement target gas fluctuates to change the oxygen concentration in the second measurement chamber. Also fluctuate. If the oxygen concentration in the second measurement chamber varies, the energization state of the abnormality determination target cell also varies.

  For this reason, the sensor control device that controls the gas sensor having such a configuration has a connection state based on whether or not the energization state of the abnormality determination target cell varies when the energization state of the variation determination reference cell varies. Whether it is normal or abnormal can be determined.

  Therefore, according to the present invention, it is possible to determine whether or not the connection state between the gas sensor and the sensor control device is abnormal without interrupting the detection operation of the specific gas concentration (NOx concentration).

  And in the above-mentioned sensor control apparatus, as described in claim 6, the gas sensor has one of its own pair of porous electrodes arranged in the first measurement chamber and the other of the porous electrodes. Is arranged in a reference atmosphere, an oxygen detection cell that generates an interelectrode voltage according to the oxygen concentration in the first measurement chamber, and one of its pair of porous electrodes is arranged in the first measurement chamber, and the oxygen detection cell An oxygen pump cell for pumping out or pumping in oxygen of the measurement target gas introduced into the first measurement chamber so that the inter-electrode voltage becomes a predetermined voltage value. It is possible to adopt a configuration in which either the oxygen pump cell or the oxygen detection cell is used.

  Since both the oxygen pump cell and the oxygen detection cell have at least one of their own pair of porous electrodes disposed in the first measurement chamber, the current-carrying state varies depending on the change in oxygen concentration in the first measurement chamber. There is. That is, when the energization state of the oxygen pump cell or the oxygen detection cell varies, the energization state of the abnormality determination target cell in which at least one of the pair of porous electrodes is disposed in the second measurement chamber varies.

  For this reason, the sensor control device that controls the gas sensor having such a configuration is connected based on whether or not the energization state of the abnormality determination target cell varies when the energization state of the oxygen pump cell or the oxygen detection cell varies. It can be determined whether the state is normal or abnormal.

  Therefore, according to the present invention, it is possible to determine whether or not the connection state between the gas sensor and the sensor control device is abnormal without interrupting the detection operation of the specific gas concentration (NOx concentration).

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an explanatory diagram showing a schematic configuration of a gas concentration measuring device 1 including a sensor control device 20 to which the present invention is applied.

  As shown in FIG. 1, the gas concentration measuring apparatus 1 includes a gas sensor 10 that detects the concentration of nitrogen oxide (NOx) in exhaust gas (hereinafter also referred to as NOx sensor 10), and a sensor control that controls the NOx sensor 10. And an apparatus 20.

The NOx sensor 10 includes a sensor main body 11 as a sensor element and a heater 12 for heating the sensor main body 11.
The sensor body 11 has a structure in which the first pump cell 31, the oxygen concentration detection cell 36, and the second pump cell 41 are laminated via insulating layers 14 and 15 mainly composed of alumina.

  Among these, the first pump cell 31 includes a first solid electrolyte body 32 made of zirconia having oxygen ion conductivity, and a first inner electrode 33 and a first outer electrode 34 disposed so as to sandwich the first solid electrolyte body 32. And is configured. The first inner electrode 33 and the first outer electrode 34 are made of platinum (Pt).

  The second pump cell 41 includes a second solid electrolyte body 42 made of zirconia having oxygen ion conductivity, and a second inner electrode disposed on the surface of the second solid electrolyte body 42 facing the insulating layer 15. 43 and the second outer electrode 44. The second inner electrode 43 and the second outer electrode 44 are made of platinum (Pt).

  Further, the oxygen concentration detection cell 36 includes a detection solid electrolyte body 37 made of zirconia having oxygen ion conductivity, a detection electrode 38 and a reference electrode 39 disposed so as to sandwich the detection solid electrolyte body 37, and It is configured with. The detection electrode 38 and the reference electrode 39 are made of platinum (Pt).

  A first measurement chamber 46 into which the measurement target gas is introduced is formed between the first pump cell 31 and the oxygen concentration detection cell 36 in the NOx sensor 10. A measurement target gas is introduced into the first measurement chamber 46 via the first diffusion resistor 16 disposed between the first pump cell 31 and the oxygen concentration detection cell 36. The first diffusion resistor 16 is composed of a porous body.

  Further, inside the NOx sensor 10, a space formed between the oxygen concentration detection cell 36 and the second pump cell 41, a hole passing through the oxygen concentration detection cell 36, the first pump cell 31 and the oxygen concentration detection. A second measurement chamber 47 is formed in communication with the space formed between the cells 36. The second measurement chamber 47 is introduced with the adjusted measurement target gas in which the oxygen concentration is adjusted to the target concentration in the first measurement chamber 46.

  The first measurement chamber 46 and the second measurement chamber 47 are separated by the second diffusion resistor 17 disposed between the first pump cell 31 and the oxygen concentration detection cell 36. The second diffusion resistor 17 is composed of a porous body.

  The first inner electrode 33 of the first pump cell 31 and the detection electrode 38 of the oxygen concentration detection cell 36 are arranged to face the first measurement chamber 46, and the second inner electrode 43 of the second pump cell 41 is It arrange | positions so that the 2nd measurement chamber 47 may be faced.

  A reference oxygen chamber 18 is formed between the oxygen concentration detection cell 36 and the second pump cell 41 in the NOx sensor 10. The reference electrode 39 of the oxygen concentration detection cell 36 and the second outer electrode 44 of the second pump cell 41 are disposed so as to face the reference oxygen chamber 18.

  The NOx sensor 10 configured as described above is configured to be capable of pumping oxygen (pumping in and out) in the first measurement chamber 46 by the first pump cell 31, and the measurement target introduced into the first measurement chamber 46. The oxygen concentration of the gas can be adjusted to the target concentration. At this time, since the oxygen concentration difference between the reference oxygen chamber 18 and the first measurement chamber 46 can be detected by the oxygen concentration detection cell 36, the first measurement chamber 46 is based on the reference oxygen chamber 18 in which the oxygen concentration is controlled to be constant. Determine the oxygen concentration.

  In the present embodiment, a constant current circuit 24 provided in the sensor control device 20 shown in FIG. 2 is used to energize the oxygen concentration detection cell 36 with a small current Icp having a constant value. Through this, oxygen is supplied from the first measurement chamber 46 (see FIG. 1) to the reference oxygen chamber 18 (see FIG. 1), whereby the oxygen concentration in the reference oxygen chamber 18 is controlled to be constant.

  The measurement target gas introduced into the first measurement chamber 46 is adjusted to the target concentration and becomes the adjusted measurement target gas, and the adjusted measurement target gas passes through the second diffusion resistor 17 to the second measurement chamber. 47.

  In the second measurement chamber 47, the nitrogen oxide (NOx) contained in the adjusted measurement target gas is decomposed by the catalytic action of the second inner electrode 43 constituting the second pump cell 41 to which a constant voltage (Vp2) is applied. The Thereby, an interelectrode current (second pump current Ip2) corresponding to the concentration of nitrogen oxides contained in the adjusted measurement target gas (in other words, the amount of oxygen obtained by decomposition) flows to the second pump cell 41. . Accordingly, the concentration of the specific gas (nitrogen oxide) in the measurement target gas can be measured based on the magnitude (or current integrated value) of the second pump current Ip2 flowing through the second pump cell 41. .

  Next, the heater 12 is formed in a flat plate shape and is disposed to face the first pump cell 31. Further, the heater 12 is controlled by the electric power supplied from the sensor control device 20 so that the temperature of the sensor body 11 becomes a predetermined activation temperature (about 550 to 900 [° C.]).

Next, a sensor control device 20 that measures the concentration of nitrogen oxides in exhaust gas using the NOx sensor 10 will be described with reference to FIG.
FIG. 2 is a circuit diagram showing a circuit configuration of the gas concentration measuring apparatus 1 including the NOx sensor 10 and the sensor control device 20.

  As shown in FIG. 2, the sensor control device 20 includes a first pump current supply circuit 21 that supplies a first pump current Ip1 to a first pump cell 31 (hereinafter also referred to as “P1 cell 31”), and an oxygen concentration detection cell 36. The first pump current Ip1 supplied by the first pump current supply circuit 21 is set to PID (proportional / proportional) so that the both-ends voltage (interelectrode voltage) Vs (hereinafter also referred to as “Vs cell 36”) becomes a constant value (425 mV). (Integration / differentiation) PID circuit 22 to be controlled, second pump voltage application circuit 23 for applying a constant second pump voltage Vp2 to second pump cell 41 (hereinafter also referred to as “P2 cell 41”), and heater 12 A heater control circuit 25 that controls the temperature and a control unit 30 that controls the entire sensor control device 20 are provided.

The sensor control device 20 has an internal resistance measurement block 48 for measuring the internal resistance of the Vs cell 36.
This internal resistance measurement block 48 is provided at the input stage of the PID circuit 22 and the two constant current sources 28 and 29 for supplying a constant current to the Vs cell 36 and connects / disconnects the Vs cell 36 and the PID circuit 22. The switch SW1 is configured to include a switch SW2 and a switch SW3 that disconnect / connect the constant current source to the Vs cell 36. The switches SW1, SW2, and SW3 provided in the internal resistance measurement block 48 are on / off controlled by the control unit 30.

  In the first pump current supply circuit 21, a predetermined first reference voltage Vf1 (for example, 2.5 V) is applied to the non-inverting input terminal, and the output of the PID circuit 22 is applied to the inverting input terminal via the current detection resistor Rp1. The operational amplifier OP1 has a P1 cell 31 connected between the output terminal and the inverting input terminal.

  Further, the first inner electrode 33 of the P1 cell 31, the second inner electrode 43 of the P2 cell 41, and the detection electrode 38 of the Vs cell 36 are commonly connected to the inverting input terminal side of the operational amplifier OP1. Therefore, the potentials of the common connection side electrodes of the P1 cell 31, the P2 cell 41, and the Vs cell 36 are all held at the same potential as the non-inverting input terminal of the operational amplifier OP1, that is, the first reference voltage Vf1.

  The second pump voltage application circuit 23 has an output terminal connected to the P2 cell 41 via the current detection resistor Rp2, and an inverting input terminal connected to the P2 cell 41 side end of the current detection resistor Rp2, and a non-inverting input terminal. An operational amplifier OP2 configured as a well-known buffer circuit for applying a voltage applied to the P2 cell 41 (second reference voltage Vf2) is provided.

  The sensor control device 20 includes a heater control circuit 25 that controls the temperature of the heater 12. The heater control circuit 25 measures the internal resistance Rpvs of the Vs cell 36, determines the temperature of the sensor body 11 based on the measured internal resistance Rpvs, and sets the temperature of the heater 12 to bring the sensor body 11 close to the target temperature. Control.

  The sensor control device 20 obtains the detected values of the first pump current Ip1 and the second pump current Ip2 by differentially amplifying the voltages at both ends of the current detection resistors Rp1 and Rp2 using a differential amplifier circuit (not shown). The voltages V (Rp1) and V (Rp2) are output to the control unit 30, and the voltage V at one end of the resistor Rp3 (the end opposite to the side connected to the operational amplifier OP4) is used as the internal resistance Rpvs of the Vs cell 36. It is configured to output (Rp3) to the control unit 30.

  The sensor control device 20 configured as described above heats the sensor main body 11 to the activation temperature (for example, 800 ° C.) with the heater 12. Then, the sensor control device 20 sets the first pump current Ip1 so that the interelectrode voltage Vs of the oxygen concentration detection cell 36 becomes a predetermined constant voltage (for example, 425 mV) in a state where the sensor body 11 is at the activation temperature. Control. Further, the sensor control device 20 applies a constant second pump voltage Vp2 (for example, 450 mV) to the second pump cell 41 in the direction in which oxygen is pumped from the second measurement chamber 47, and flows to the second pump cell 41. The second pump current Ip2 is detected.

  That is, when the sensor control device 20 controls the first pump current Ip1 as described above to perform oxygen pumping (pumping in and out) in the first measuring chamber 46, the oxygen concentration in the first measuring chamber 46 is It is kept at a low oxygen concentration (≈0%). Thus, the measurement target gas introduced into the first measurement chamber 46 is adjusted to the target concentration and becomes the adjusted measurement target gas, and the adjusted measurement target gas is introduced into the second measurement chamber 47.

  Further, the sensor control device 20 maintains the second pump voltage Vp2 at a predetermined voltage, so that the nitrogen oxide in the second measurement chamber 47 is decomposed by the catalytic action of the second inner electrode 43, and the amount corresponding to the decomposition amount is determined. The second pump current Ip2 flows through the second pump cell 41. Thus, since the second pump current Ip2 has a magnitude corresponding to the concentration of nitrogen oxides, the nitrogen oxides in the measurement target gas are determined based on the second pump current Ip2 (current value, current integral value, etc.). The density can be determined.

  The specific gas detection process for determining the concentration of the specific gas (nitrogen oxide) in the measurement target gas is executed by the control unit 30. That is, the control unit 30 that executes the specific gas detection process controls the operation of each unit in the sensor control device 20 (for example, control of the first pump current Ip1 and the like) and information necessary for gas detection (second pump current). Ip2 etc.) can be acquired to determine the concentration of nitrogen oxide in the measurement target gas.

Next, the internal resistance measurement block 48 for measuring the internal resistance of the Vs cell 36 in the sensor control device 20 will be described.
The operational amplifier OP3 provided in the internal resistance measurement block 48 has its input terminal connected to the output terminal of the Vs cell 36 via the switch SW1. The output terminal of the operational amplifier OP3 is connected to the input terminal of the PID circuit 22.

The operational amplifier OP3 forms a sample and hold circuit together with a capacitor C1 provided between its input terminal and a ground potential (hereinafter also referred to as “GND”).
The sample hold circuit composed of the operational amplifier OP3 and the capacitor C1 holds the output voltage Vs of the Vs cell 36 immediately before supplying the internal resistance measurement current for measuring the internal resistance of the Vs cell 36. It plays a role of outputting to the PID circuit 22.

  The operational amplifier OP4 is a two-input differential amplifier. The + side input terminal is connected to the output terminal of the operational amplifier OP3, and the − side input terminal is connected to the output terminal of the Vs cell 36. The operational amplifier OP4 supplies the voltage held in the sample hold circuit (the output voltage Vs of the Vs cell 36 immediately before applying the internal resistance measurement voltage) and the internal resistance measurement current -Iconst to the Vs cell 36. The difference (hereinafter also referred to as voltage change amount ΔVs) from the terminal voltage of the Vs cell 36 is output to the control unit 30 and the heater control circuit 25 via the resistor Rp3.

  The switch SW1 is provided between the output terminal of the Vs cell 36 and the input terminal of the operational amplifier OP3, and is controlled to be turned on / off by the control unit 30 to change the operation state of the sensor control device 20 from the gas concentration measurement state or the internal resistance. It is provided to switch to one of the measurement states.

  When the operation state of the sensor control device 20 is set to the gas concentration measurement state, the switch SW1 is set to the on state (short circuit state), and the operational amplifier OP3 outputs the Vs cell 36 to the PID circuit 22. Input the voltage. Further, when the operation state of the sensor control device 20 is set to the internal resistance measurement state, the switch SW1 is set to an off state (open state), and the operational amplifier OP3 has a voltage (internal resistance) held in the capacitor C1. The output voltage Vs of the Vs cell 36 immediately before the measurement voltage is applied is output to the PID circuit 22.

  The switch SW2 is provided between the output terminal of the Vs cell 36 and the constant current source 28, and is controlled to be turned on / off by the control unit 30, so that a current − for measuring internal resistance from the constant current source 28 is supplied. It plays the role of supplying / blocking Icon to the Vs cell 36.

  The switch SW3 is provided between the output terminal of the Vs cell 36 and the constant current source 29. The switch SW3 is on / off controlled by the control unit 30 and flows to the Vs cell 36 via the switch SW2. It plays the role of supplying / blocking the current + Iconst having the opposite polarity to the Vs cell 36.

  Then, the control unit 30 executes an internal resistance measurement process for calculating the internal resistance Rpvs of the Vs cell 36 at a predetermined timing. In the internal resistance measurement process, the switches SW1, SW2, and SW3 are turned on / off, a constant current −Iconst is supplied to the Vs cell 36, and the voltage change amount ΔVs of the Vs cell 36 due to the energization of the constant current −Iconst is detected. Then, a series of processes of calculating the internal resistance Rpvs of the Vs cell 36 based on the constant current −Iconst and the voltage change amount ΔVs is performed.

  In addition, the gas concentration measuring apparatus 1 of this embodiment is provided in order to measure the nitrogen oxide density | concentration in the exhaust gas of a motor vehicle engine, and the control part 30 of the sensor control apparatus 20 is variously detected from the gas sensor 10. Information is output to an electronic control unit (ECU). The electronic control unit (ECU) comprehensively controls each part of the automobile and executes, for example, air-fuel ratio control.

  In addition to the specific gas detection process and the internal resistance measurement process, the control unit 30 of the sensor control apparatus 20 determines whether the connection path (wiring path) connecting the NOx sensor 10 and the sensor control apparatus 20 is abnormal. A process for determining whether or not (connection determination process) is executed.

Therefore, the connection determination process executed by the control unit 30 will be described.
FIG. 3 shows a flowchart showing the processing contents of the connection determination processing.
When the connection determination process is activated, first, in S110 (S represents a step), it is determined whether or not the NOx sensor 10 is in an activated state. If it is in an activated state, an affirmative determination is made. Then, the process proceeds to S120, and if it is not in the activated state, a negative determination is made, and the same step is repeatedly executed until the activated state is reached.

  In S110, specifically, it is determined whether or not the determination temperature of the NOx sensor 10 determined based on the internal resistance Rpvs of the Vs cell 36 measured in the internal resistance measurement process is a predetermined activation temperature. Thus, it is determined whether or not the NOx sensor 10 is in an activated state.

  When an affirmative determination is made in S110 and the process proceeds to S120, in S120, the first pump current Ip1 and the second pump current Ip2 are detected and accumulated, and whether or not a factor that causes the energization state of the second pump cell 41 to fluctuate has occurred. Is executed (information sampling process).

FIG. 4 is a flowchart showing the contents of the information sampling process.
In the information sampling process, first, in S210, an initialization process of internal variables used for the process is executed. Specifically, initial values (such as 0) for each variable such as an Ip1 trajectory length integration variable (hereinafter also referred to as ΣIp1 trajectory length), an Ip2 trajectory length integration variable (hereinafter also referred to as ΣIp2 trajectory length), and a measurement time variable. ) To initialize each variable.

  The Ip1 trajectory length integration variable (ΣIp1 trajectory length) is the amount of change in the energized state of the first pump cell 31 (specifically, the first pump current Ip1) (in other words, the trajectory length of the waveform of the first pump current Ip1). ) Is a variable for recording a value corresponding to. The Ip2 trajectory length integration variable (ΣIp2 trajectory length) is a change amount of the energization state (specifically, the second pump current Ip2) of the second pump cell 41 (in other words, the trajectory length of the waveform of the second pump current Ip2). It is a variable for recording the corresponding value. The measurement time variable is a variable for recording the elapsed time.

  In S210, after the measurement time variable is initialized, a timer count process for updating the measurement time variable for each unit time and measuring the elapsed time is started. The timer count process is executed in parallel with the present process (information sampling process).

  In the next S220, the elapsed time is determined using the value of the measurement time variable, and the process waits until one predetermined sampling time elapses. At the time when one sampling time elapses, the first pump current Ip1 and the first The process which detects 2 pump current Ip2 is performed.

  In subsequent S230, using the numerical values of the first pump current Ip1 and the second pump current Ip2 detected at the current sampling time (numerical value detection time), the Ip1 trajectory length integration variable (ΣIp1 trajectory length) and the Ip2 trajectory length integration variable ( (ΣIp2 locus length) is updated.

  The Ip1 trajectory length integration variable is updated by calculating a difference value between the current detection value Ip1 (n) and the previous detection value Ip1 (n−1) in the first pump current Ip1 (hereinafter referred to as a trajectory (Ip1 (n) −Ip1 ( n-1)) and the calculated difference value (trajectory (Ip1 (n) -Ip1 (n-1)) is added to the Ip1 trajectory length integration variable. At the time of detection, a calculation process is executed using a predetermined value as the previous detection value.

Further, the update of the Ip2 trajectory length integration variable is executed by performing the same calculation as the update of the Ip1 trajectory length integration variable using the second pump current Ip2.
In next step S240, it is determined whether or not the Ip1 trajectory length integration variable (ΣIp1 trajectory length) is equal to or greater than a threshold value (predetermined first current trajectory fluctuation determination value). If the determination is negative, the process proceeds to S220 again.

  The first current locus fluctuation determination value is a determination value determined to determine that the energization state of the first pump cell 31 has changed, and is determined based on actual measurement data using an actual NOx sensor. Can do. For example, the first current trajectory fluctuation determination value is obtained when the energization state of the first pump cell 31 fluctuates in relation to a factor that fluctuates the energization state of the second pump cell 41 (for example, the oxygen concentration change of the measurement target gas). It can be determined based on the first pump current Ip1 (specifically, the locus integrated value of the first pump current Ip1).

That is, in S240, based on the Ip1 trajectory length integration variable (ΣIp1 trajectory length), a process of determining whether or not a factor that causes the energization state of the second pump cell 41 to occur is performed.
If an affirmative determination is made in S240, the present process (information sampling process) is terminated, and the process proceeds to the connection determination process again.

  Next, in S130 in the connection determination process, a process (Ip2 + wiring determination process) for determining whether or not there is an abnormality in the connection path (Ip2 + wiring path) connecting the second pump cell 41 and the sensor control device 20 is executed. .

FIG. 5 is a flowchart showing the contents of the Ip2 + wiring determination process.
In the Ip2 + wiring determination process, first, in S310, the value of the Ip2 trajectory length integration variable (ΣIp2 trajectory length) obtained by the information sampling process is equal to or greater than a determination value (predetermined second current trajectory fluctuation determination value). If the determination is affirmative, the process proceeds to S320. If the determination is negative, the process proceeds to S330.

  The second current trajectory fluctuation determination value is a determination value determined to determine that the energization state of the second pump cell 41 has changed, and is determined based on actual measurement data using an actual NOx sensor. Can do. For example, the second current trajectory fluctuation determination value is determined when the second pump cell 41 is energized due to the factor (factor that varies the energization state of the second pump cell 41) determined in the above-described information sampling process (specifically, S240). It can be determined based on the second pump current Ip2 (specifically, the locus integrated value of the waveform of the second pump current Ip2) when the state changes.

That is, in S310, processing for determining whether or not the energization state of the second pump cell 41 has changed using the Ip2 trajectory length integration variable (ΣIp2 trajectory length) is performed.
When an affirmative determination is made in S310 and the process proceeds to S320, in S320, it is determined that the Ip2 + wiring path is normal (in other words, there is no abnormality), and the path abnormality flag Fa indicating that the Ip2 + wiring path is in an abnormal state. Perform processing to reset.

  When a negative determination is made in S310 and the process proceeds to S330, in S330, the time required for the information sampling process (S120) is set to a threshold (predetermined required time determination value) based on the numerical value of the measurement time variable that starts measurement in the information sampling process. ) Or not. If an affirmative determination is made, the process proceeds to S350, and if a negative determination is made, the process proceeds to S340.

  The required time determination value is determined based on a generation period of a factor that changes the energization state of the second pump cell 41. In other words, the required time determination value is a time required for the information sampling process (in other words, the required time for sampling the first pump current Ip1 and the second pump current Ip2) within a range that does not cause an error in the state determination of Ip2 + wiring path. Is set in time.

  That is, when the time required for the information sampling process is long, the long time required is one of the causes of increasing the Ip2 trajectory length integration variable (ΣIp2 trajectory length). Even when the pump current Ip2 varies only slightly, the Ip2 trajectory length integration variable may be a large value. For this reason, when the time required for the information sampling process is long, it may not be possible to accurately determine whether or not the energization state of the second pump cell 41 has changed.

For this reason, when an affirmative determination is made in S330 and the process proceeds to S350, the state determination of the Ip2 + wiring path is not performed in S350.
On the other hand, when a negative determination is made in S330 and the process proceeds to S340, in S340, it is determined that the Ip2 + wiring path is in an abnormal state, and a process of setting a path abnormality flag Fa indicating that the Ip2 + wiring path is in an abnormal state is performed. .

  When the route abnormality flag Fa is set, an abnormality handling process that is executed separately is started. In the abnormality handling process, a process for notifying the user that the connection path (Ip2 + wiring path) connecting the second pump cell 41 and the sensor control device 20 is in an abnormal state, and a specific gas obtained by the specific gas detection process A process for notifying that there is an error in concentration, a process for prohibiting the use of the specific gas concentration obtained in the specific gas detection process for other control processes, and the like are executed.

When one of the processes of S320, S340, and S350 is completed, the present process (Ip2 + wiring determination process) is ended, and the process is again transferred to the connection determination process.
Thereafter, the process of S130 ends and the connection determination process ends.

The connection determination process is repeatedly executed at regular intervals while the sensor control device 20 is activated.
Here, FIG. 12 shows measurement results when the first pump current Ip1 and the second pump current Ip2 are measured using an actual NOx sensor.

  As shown in FIG. 12, when the first pump current Ip1 (in other words, the energized state of the first pump cell 31) fluctuates greatly, the second pump current Ip2 (in other words, the first pump current Ip2 in other words) is followed. It can be seen that the energization state of the two pump cells 41 varies greatly. Such a change in the energized state occurs due to a change in the oxygen concentration of the measurement target gas introduced into the first measurement chamber 46, for example.

  Therefore, as in the connection determination process described above, the second state is determined by determining whether the energization state of the first pump current Ip1 varies based on the Ip1 locus length integration variable (ΣIp1 locus length) (S240). The time when the energized state of the pump cell 41 varies can be specified.

  Then, after it is determined that the energization state of the first pump current Ip1 has fluctuated (Yes in S240) and the timing when the energization state of the second pump cell 41 fluctuates is specified, the energization state of the second pump cell 41 is actually By determining whether or not it has changed (S310), it can be determined whether or not the Ip2 + wiring path is in an abnormal state.

  As described above, the sensor control device 20 of the present embodiment, when it is determined that the energization state of the first pump cell 31 (first pump current Ip1) has changed, the energization state of the second pump cell 41 (second Whether the connection state between the second pump cell 41 and the sensor control device 20 is a normal state or an abnormal state is determined depending on whether or not the pump current Ip2) has fluctuated.

  For this reason, the sensor control device 20 does not input an abnormality detection signal to the cell of the NOx sensor 10, and the connection state between the second pump cell 41 and the sensor control device 20 is normal or abnormal. Can be determined. That is, the sensor control device 20 has an advantage that it is not necessary to interrupt gas detection when determining whether the connection state between the second pump cell 41 and the sensor control device 20 is a normal state or an abnormal state.

  Therefore, according to the sensor control device 20 of the present embodiment, the connection between the NOx sensor 10 (specifically, the second pump cell 41) and the sensor control device 20 can be performed without interrupting the specific gas (NOx) concentration detection operation. It becomes possible to determine whether or not the state is abnormal. That is, the sensor control device 20 has the effect of being able to execute the detection operation of the specific gas (NOx) concentration and the abnormality determination operation of the connection state between the NOx sensor 10 and the sensor control device 20 in parallel. Become.

  Further, since the sensor control device 20 determines using the Ip1 trajectory length integration variable (ΣIp1 trajectory length) (S240), it is determined whether or not the energization state (first pump current Ip1) of the first pump cell 31 has changed. While being able to judge appropriately, the time when the energization state of the 2nd pump cell 41 fluctuates can be judged appropriately.

  Further, since the sensor control device 20 determines using the Ip2 trajectory length integration variable (ΣIp2 trajectory length) (S310), it is determined whether or not the energization state (second pump current Ip2) of the second pump cell 41 has changed. While being able to determine appropriately, it can be determined appropriately whether the connection state of the NOx sensor 10 (2nd pump cell 41) and the sensor control apparatus 20 is abnormal.

  In this embodiment, the NOx sensor 10 corresponds to the gas sensor described in the claims, the second pump cell 41 corresponds to the abnormality determination target cell, the first pump cell 31 corresponds to the fluctuation determination reference cell, The control unit 30 that executes S120 (information sampling processing) corresponds to an energization state variation determination unit, and the control unit 30 that executes S130 (Ip2 + wiring determination processing) corresponds to a connection state determination unit.

  Further, the Ip1 trajectory length integration variable (ΣIp1 trajectory length) corresponds to the reference cell fluctuation amount, the first current trajectory fluctuation determination value corresponds to the reference fluctuation determination value, and the Ip2 trajectory length integration variable (ΣIp2 trajectory length) corresponds to the target cell. It corresponds to the fluctuation amount, and the second current locus fluctuation determination value corresponds to the target fluctuation determination value.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various aspect can be taken.
For example, in the above embodiment (hereinafter also referred to as the first embodiment), the energization state of the fluctuation determination reference cell is determined by the first pump current Ip1, and the energization state of the abnormality determination target cell is determined by the second pump current Ip2. The embodiment for determining the abnormality of the connection path has been described, but a state quantity different from the first pump current Ip1 and the second pump current Ip2 may be used.

  Therefore, in the second embodiment, the energization state of the variation determination reference cell is determined using the interelectrode voltage (first pump voltage Vp1) of the first pump cell 31, and the energization state of the abnormality determination target cell is the second pump current Ip2. An embodiment will be described in which a determination is made by using and the connection path abnormality determination is performed.

  In the second embodiment, in detail, the abnormality determination of the connection path is performed using the locus length of the first pump voltage Vp1 and the integrated value (area) of the second pump current Ip2. The basic configuration of the gas concentration measurement device of the second embodiment is the same as that of the gas concentration measurement device 1 of the first embodiment, and the processing content of the connection determination process executed by the control unit 30 is different. In the following description, the connection determination process will be mainly described. In addition, the component similar to 1st Embodiment among the components of 2nd Embodiment is represented using the same code | symbol.

  First, the processing content of the connection determination processing in the gas concentration measurement apparatus of the second embodiment differs from the processing content of S120 and the processing content of S130 in the flowchart shown in FIG.

  FIG. 6 is a flowchart showing the processing content (second information sampling processing) of S120 in the second embodiment, and FIG. 7 is a flowchart showing the processing content (second Ip2 + wiring determination processing) of S130 in the second embodiment. Show.

  In the second information sampling process, first, in S410, a process of calculating an average value Ip2 # avg of the second pump current Ip2 is executed. The average value Ip2 # avg is calculated based on the average value (movement) of the second pump current Ip2 during the detection period based on the accumulated data of the second pump current Ip2 detected during the predetermined detection period. There are calculation methods for calculating (average value).

  In the next S420, initialization processing of internal variables used for the processing is executed. Specifically, initial values (such as 0) are substituted for variables such as Vp1 trajectory length integration variable (hereinafter also referred to as ΣVp1 trajectory length), Ip2 area variable (hereinafter also referred to as ΣIp2 area), and measurement time variable. By doing so, each variable is initialized.

  Note that the Vp1 trajectory length integration variable (ΣVp1 trajectory length) is the amount of change in the energization state of the first pump cell 31 (specifically, the first pump voltage Vp1) (in other words, the trajectory length of the waveform of the first pump voltage Vp1). ) Is a variable for recording a value corresponding to. The Ip2 area variable (ΣIp2 area) is a value corresponding to the amount of change (in other words, the integrated value of the waveform of the second pump current Ip2) in the energization state of the second pump cell 41 (specifically, the second pump current Ip2). Is a variable for recording. The measurement time variable is a variable for recording the elapsed time.

  In S420, after the measurement time variable is initialized, a timer count process for updating the measurement time variable every unit time and measuring the elapsed time is started. The timer count process is executed in parallel with the present process (second information sampling process).

  In the next S430, the elapsed time is determined using the value of the measurement time variable, and the process waits until one predetermined sampling time elapses. When one sampling time elapses, the first pump voltage Vp1 and the first pump voltage Vp1 The process which detects 2 pump current Ip2 is performed.

  In subsequent S440, using the numerical values of the first pump voltage Vp1 and the second pump current Ip2 detected at the current sampling time (numerical value detection time), the Vp1 trajectory length integration variable (ΣVp1 trajectory length) and the Ip2 area variable (ΣIp2 area) ) Is updated.

  The Vp1 trajectory length integration variable is updated by calculating a difference value between the current detection value Vp1 (n) and the previous detection value Vp1 (n-1) (hereinafter referred to as a trajectory (Vp1 (n) -Vp1 ( (also referred to as n-1)), and the calculated difference value (trajectory (Vp1 (n) -Vp1 (n-1))) is added to the Vp1 trajectory length integration variable. At the time of detection, a calculation process is executed using a predetermined value as the previous detection value.

  The update of the Ip2 area variable is performed by first calculating a difference value between the current detection value Ip2 (n) in the second pump current Ip2 and the average value Ip2 # avg obtained by the calculation of S410, and calculating the absolute value of the difference value. A value (currently calculated area) obtained by multiplying the value by one sampling time is calculated. Then, the Ip2 area variable is updated by adding the current calculated area to the Ip2 area variable (ΣIp2 area).

  In next S450, it is determined whether or not the Vp1 trajectory length integration variable (ΣVp1 trajectory length) is equal to or greater than a threshold value (predetermined first voltage trajectory fluctuation determination value). If the information sampling process is terminated and a negative determination is made, the process proceeds to S430 again.

  The first voltage locus fluctuation determination value is a determination value determined to determine that the energization state of the first pump cell 31 has changed, and is determined based on actual measurement data using an actual NOx sensor. Can do. For example, the first voltage trajectory fluctuation determination value is obtained when the energization state of the first pump cell 31 fluctuates in relation to a factor that fluctuates the energization state of the second pump cell 41 (for example, the oxygen concentration change of the measurement target gas). It can be determined based on the first pump voltage Vp1 (specifically, the locus integrated value of the first pump voltage Vp1).

That is, in S450, based on the Vp1 trajectory length integration variable (ΣVp1 trajectory length), processing is performed to determine whether or not a factor that causes the energization state of the second pump cell 41 to fluctuate has occurred.
If an affirmative determination is made in S450, the present process (second information sampling process) ends, and the process shifts again to the connection determination process.

  Next, in S130 in the connection determination process of the second embodiment, a process of determining whether or not there is an abnormality in the connection path (Ip2 + wiring path) connecting the second pump cell 41 and the sensor control device 20 (second Ip2 + wiring) Determination process).

  As shown in FIG. 7, in the second Ip2 + wiring determination process, first, in S510, the numerical value of the Ip2 area variable (ΣIp2 area) obtained by the second information sampling process is determined as a determination value (predetermined second current area). It is determined whether or not it is equal to or greater than (variation determination value). If an affirmative determination is made, the process proceeds to S520.

  The second current area variation determination value is a determination value determined to determine that the energization state of the second pump cell 41 has changed, and is determined based on actual measurement data using an actual NOx sensor. Can do. For example, the second current area variation determination value is derived from the factor (factor that varies the energization state of the second pump cell 41) determined in the second information sampling process (specifically, S450) described above. Can be determined based on the second pump current Ip2 (specifically, the integrated value of the waveform of the second pump current Ip2) when the energization state of f is changed.

That is, in S510, a process of determining whether or not the energization state of the second pump cell 41 has changed using the Ip2 area variable (ΣIp2 area) is performed.
When an affirmative determination is made in S510 and the process proceeds to S520, in S520, it is determined that the Ip2 + wiring path is normal (in other words, there is no abnormality), and the path abnormality flag Fa indicating that the Ip2 + wiring path is in an abnormal state. Perform processing to reset.

  When a negative determination is made in S510 and the process proceeds to S530, in S530, the time required for the second information sampling process (S120) is set to a threshold (predetermined based on the numerical value of the measurement time variable that has started measurement in the second information sampling process. It is determined whether or not it is equal to or greater than (required time determination value). If an affirmative determination is made, the process proceeds to S550, and if a negative determination is made, the process proceeds to S540.

  The required time determination value is determined based on a generation period of a factor that changes the energization state of the second pump cell 41. That is, the required time determination value is the required time of the second information sampling process (in other words, the required time for sampling the first pump voltage Vp1 and the second pump current Ip2), and does not cause an error in the state determination of Ip2 + wiring path. The time is set within the range.

  That is, when the time required for the second information sampling process is long, the long time required is one of the causes of increasing the Ip2 area variable (ΣIp2 area). Even when the current Ip2 varies only slightly, the Ip2 area variable may be a large value. For this reason, when the time required for the second information sampling process is long, it may not be possible to accurately determine whether or not the energization state of the second pump cell 41 has changed.

For this reason, when an affirmative determination is made in S530 and the process proceeds to S550, the state determination of the Ip2 + wiring path is not performed in S550.
On the other hand, when a negative determination is made in S530 and the process proceeds to S540, in S540, it is determined that the Ip2 + wiring path is in an abnormal state, and a process of setting a path abnormality flag Fa indicating that the Ip2 + wiring path is in an abnormal state is performed. .

  When the route abnormality flag Fa is set, an abnormality handling process that is executed separately is started. In the abnormality handling process, a process for notifying the user that the connection path (Ip2 + wiring path) connecting the second pump cell 41 and the sensor control device 20 is in an abnormal state, and a specific gas obtained by the specific gas detection process A process for notifying that there is an error in concentration, a process for prohibiting the use of the specific gas concentration obtained in the specific gas detection process for other control processes, and the like are executed.

When any one of S520, S540, and S550 is completed, the present process (second Ip2 + wiring determination process) is ended, and the process shifts to the connection determination process again.
Thereafter, the process of S130 in the second embodiment ends, and the connection determination process of the second embodiment ends. The connection determination process is repeatedly executed at regular intervals while the sensor control device 20 is activated.

  As can be seen from the measurement results shown in FIG. 12, when the first pump current Ip1 (in other words, the energization state of the first pump cell 31) greatly fluctuates, the second pump current Ip2 (in other words, follows this). If so, the energization state of the second pump cell 41) greatly fluctuates. Such a change in the energized state occurs due to a change in the oxygen concentration of the measurement target gas introduced into the first measurement chamber 46, for example.

  Therefore, as in the connection determination process of this embodiment, it is determined whether or not the energization state of the first pump cell 31 varies based on the Vp1 trajectory length integration variable (ΣVp1 trajectory length) (S450). The time when the energization state of the two-pump cell 41 varies can be specified.

  Then, after it is determined that the energization state of the first pump cell 31 has changed (Yes determination in S450) and the time when the energization state of the second pump cell 41 changes is specified, the energization state of the second pump cell 41 actually varies. By determining whether or not (S510), it can be determined whether or not the Ip2 + wiring path is in an abnormal state.

  As described above, the sensor control device 20 according to the second embodiment, when it is determined that the energization state of the first pump cell 31 (first pump voltage Vp1) has changed, the energization state (first of the second pump cell 41). Whether or not the connection state between the second pump cell 41 and the sensor control device 20 is a normal state or an abnormal state is determined depending on whether or not the 2 pump current Ip2) has fluctuated.

  For this reason, the sensor control device 20 of the second embodiment does not input an abnormality detection signal to the cell of the NOx sensor 10 as in the first embodiment, and the second pump cell 41 and the sensor control device 20. Since it is possible to determine whether the connection state is normal or abnormal, there is an advantage that it is not necessary to interrupt gas detection when determining whether the connection state is normal or abnormal. .

  Therefore, according to the sensor control device 20 of the present embodiment, the connection between the NOx sensor 10 (specifically, the second pump cell 41) and the sensor control device 20 is performed without interrupting the detection operation of the specific gas concentration (NOx). It becomes possible to determine whether or not the state is abnormal.

  Further, since the sensor control device 20 determines using the Vp1 trajectory length integration variable (ΣVp1 trajectory length) (S450), it is determined whether or not the energization state (first pump voltage Vp1) of the first pump cell 31 has changed. While being able to judge appropriately, the time when the energization state of the 2nd pump cell 41 fluctuates can be judged appropriately.

  Further, since the sensor control device 20 makes a determination using the Ip2 area variable (ΣIp2 area) (S510), it is appropriately determined whether or not the energization state (second pump current Ip2) of the second pump cell 41 has changed. In addition, it is possible to appropriately determine whether or not the connection state between the NOx sensor 10 (second pump cell 41) and the sensor control device 20 is abnormal.

  In this embodiment, the control unit 30 that executes S120 (second information sampling process) corresponds to the energization state variation determination means, and the control unit 30 that executes S130 (second Ip2 + wiring determination process) determines the connection state. Corresponds to means.

  Further, the Vp1 trajectory length integration variable (ΣVp1 trajectory length) corresponds to the reference cell fluctuation amount, the first voltage trajectory fluctuation determination value corresponds to the reference fluctuation determination value, and the Ip2 area variable (ΣIp2 area) corresponds to the target cell fluctuation amount. The second current area fluctuation determination value corresponds to the target fluctuation determination value.

  Next, as a third embodiment, determination is made using the interelectrode voltage (oxygen detection voltage Vs) of the oxygen concentration detection cell 36 as the energization state of the fluctuation determination reference cell, and the second pump current as the energization state of the abnormality determination target cell. An embodiment will be described in which determination is performed using Ip2 and abnormality determination of a connection path is performed.

  In the third embodiment, specifically, the abnormality determination of the connection path is performed using the integrated value (area) of the oxygen detection voltage Vs and the integrated value (area) of the second pump current Ip2. The basic configuration of the gas concentration measurement device of the third embodiment is the same as that of the gas concentration measurement device 1 of the first embodiment, and the processing content of the connection determination process executed by the control unit 30 is different. In the following description, the connection determination process will be mainly described. In addition, the component similar to 1st Embodiment among the components of 3rd Embodiment is represented using the same code | symbol.

  First, the processing content of the connection determination processing in the gas concentration measurement device of the third embodiment differs from the processing content of S120 and the processing content of S130 in the flowchart shown in FIG.

  FIG. 8 is a flowchart showing the processing content (third information sampling processing) of S120 in the second embodiment, and FIG. 9 is a flowchart showing the processing content (third Ip2 + wiring determination processing) of S130 in the second embodiment. Show.

  In the second information sampling process, first, in S610, a process of calculating the average value Vs # avg of the oxygen detection voltage Vs and the average value Ip2 # avg of the second pump current Ip2 is executed. The average value Vs # avg and the average value Ip2 # avg are calculated based on the oxygen detection voltage Vs detected during a predetermined detection period and the accumulated data of the second pump current Ip2 during the detection period. There are calculation methods for calculating the average value (moving average value) of the oxygen detection voltage Vs and the second pump current Ip2, respectively.

  In next step S620, initialization processing of internal variables used for the processing is executed. Specifically, a Vs area variable (hereinafter also referred to as ΣVs area), an Ip2 area variable (hereinafter also referred to as ΣIp2 area), a Vs excess frequency variable (hereinafter also referred to as ΣVs excess frequency), an Ip2 excess frequency variable (hereinafter, Each variable is initialized by substituting an initial value (such as 0) for each variable such as a measurement time variable.

  Note that the Vs area variable (ΣVs area) corresponds to the amount of change in the energization state (specifically, the oxygen detection voltage Vs) of the oxygen concentration detection cell 36 (in other words, the integrated value of the waveform of the oxygen detection voltage Vs). A variable for recording a value. The Ip2 area variable (ΣIp2 area) is a value corresponding to the amount of change (in other words, the integrated value of the waveform of the second pump current Ip2) in the energization state of the second pump cell 41 (specifically, the second pump current Ip2). Is a variable for recording.

  The Vs excess number variable (ΣVs excess number) is a variable for recording the number of times that the oxygen detection voltage Vs is equal to or higher than a predetermined threshold value (Vs voltage excess determination value). The Ip2 excess count variable (ΣIp2 excess count) is a variable for recording the number of times that the second pump current Ip2 is equal to or greater than a predetermined threshold (Ip2 excess determination value). Furthermore, the measurement time variable is a variable for recording the elapsed time.

  In S620, after the measurement time variable is initialized, a timer count process for updating the measurement time variable for each unit time and measuring the elapsed time is started. The timer count process is executed in parallel with the present process (third information sampling process).

  In the next step S630, the elapsed time is determined using the value of the measurement time variable, and it waits until one predetermined sampling time elapses. When one sampling time elapses, the oxygen detection voltage Vs and the second time are measured. A process of detecting the pump current Ip2 is executed.

  In subsequent S640, the Vs area variable (ΣVs area) and the Ip2 area variable (ΣIp2 area) are updated using the oxygen detection voltage Vs and the second pump current Ip2 detected at the current sampling time (numerical value detection time). Process.

  The Vs area variable is updated by first calculating the difference value between the current detection value Vs (n) at the oxygen detection voltage Vs and the average value Vs # avg obtained by the calculation of S610, and the absolute value of the difference value. A value (currently calculated area) obtained by multiplying by 1 sampling time is calculated. Then, the Vs area variable is updated by adding the currently calculated area to the Vs area variable (ΣVs area).

  The update of the Ip2 area variable is performed by first calculating a difference value between the current detection value Ip2 (n) in the second pump current Ip2 and the average value Ip2 # avg obtained by the calculation of S610, and calculating the absolute value of the difference value. A value (currently calculated area) obtained by multiplying the value by one sampling time is calculated. Then, the Ip2 area variable is updated by adding the current calculated area to the Ip2 area variable (ΣIp2 area).

  In next S650, it is determined whether or not the current detection value Vs (n) of the oxygen detection voltage Vs is equal to or greater than a threshold value (predetermined Vs voltage excess determination value). If an affirmative determination is made, the process proceeds to S660. If a negative determination is made, the process proceeds to S670.

  The Vs voltage excess determination value is a determination value determined for determining that the energization state of the oxygen concentration detection cell 36 has changed, and is determined based on actual measurement data using an actual NOx sensor. it can. For example, the Vs voltage excess determination value is the oxygen when the energization state of the oxygen concentration detection cell 36 fluctuates in relation to a factor that varies the energization state of the second pump cell 41 (for example, the oxygen concentration change of the measurement target gas). It can be determined based on the detection voltage Vs (specifically, the peak value of the oxygen detection voltage Vs).

When an affirmative determination is made in S650 and the process proceeds to S660, a process of incrementing the Vs excess count variable (ΣVs excess count) by 1 is performed in S660.
When a negative determination is made in S650 or when S660 ends and the process proceeds to S670, in S670, the current detection value Ip2 (n) of the second pump current Ip2 is equal to or greater than a threshold value (predetermined Ip2 current excess determination value). If the determination is affirmative, the process proceeds to S680. If the determination is negative, the process proceeds to S690.

  The Ip2 current excess determination value is a determination value determined to determine that the energization state of the second pump cell 41 has changed, and can be determined based on actual measurement data using an actual NOx sensor. . For example, the Ip2 current excess determination value is the second pump current when the energization state of the second pump cell 41 varies due to the factor determined in S650 described above (the factor that varies the energization state of the second pump cell 41). It can be determined based on Ip2 (specifically, the peak value of the second pump current Ip2).

When an affirmative determination is made in S670 and the process proceeds to S680, a process of incrementing the Ip2 excess count variable (ΣIp2 excess count) by 1 is performed in S680.
When a negative determination is made in S670, or when S680 ends and the process proceeds to S690, in S690, the Vs area variable (ΣVs area) is equal to or greater than a threshold value (predetermined Vs voltage area fluctuation determination value) and exceeds Vs. It is determined whether or not the condition that the frequency variable (number of times of exceeding ΣVs) is equal to or greater than a threshold value (predetermined Vs frequency determination value) is satisfied, and if an affirmative determination is made, this processing (third information sampling processing) is terminated. If a negative determination is made, the process proceeds to S630 again.

  The Vs voltage area variation determination value is a determination value determined to determine that the energization state of the oxygen concentration detection cell 36 has changed, and is determined based on actual measurement data using an actual NOx sensor. Can do. For example, the Vs voltage area variation determination value is obtained when the energization state of the oxygen concentration detection cell 36 varies in association with a factor that varies the energization state of the second pump cell 41 (for example, a change in the oxygen concentration of the measurement target gas). It can be determined based on the oxygen detection voltage Vs (specifically, the integrated value of the waveform of the oxygen detection voltage Vs).

  The Vs count determination value is a determination value determined for determining that the energization state of the oxygen concentration detection cell 36 has changed, and can be determined based on actual measurement data using an actual NOx sensor. . For example, the Vs count determination value is the oxygen detection when the energization state of the oxygen concentration detection cell 36 is changed in relation to a factor that varies the energization state of the second pump cell 41 (for example, a change in the oxygen concentration of the measurement target gas). It can be determined based on the voltage Vs (specifically, the number of times the oxygen detection voltage Vs exceeds the Vs voltage excess determination value (determination value used in S650)).

  That is, in S690, a process is performed to determine whether or not a factor that causes a change in the energization state of the second pump cell 41 has occurred based on the Vs area variable (ΣVs area) and the Vs excess count variable (ΣVs excess count).

  In the case of determining based on the Vs area variable (ΣVs area) and the Vs excess number variable (ΣVs excess number), only one of the Vs area variable (ΣVs area) and the Vs excess number variable (ΣVs excess number) is used. Compared with the case of making a determination based on this, a more accurate determination can be made.

If an affirmative determination is made in S690, the present process (third information sampling process) ends, and the process shifts to the connection determination process again.
Next, in S130 in the connection determination process of the third embodiment, a process for determining whether or not there is an abnormality in the connection path (Ip2 + wiring path) connecting the second pump cell 41 and the sensor control device 20 (third Ip2 + wiring) Determination process).

  As shown in FIG. 9, in the third Ip2 + wiring determination process, first, in S710, the value of the Ip2 area variable (ΣIp2 area) and the Ip2 excess count variable (ΣIp2 excess count) obtained in the third information sampling process are used. The determination process is performed. Specifically, the numerical value of the Ip2 area variable (ΣIp2 area) is equal to or greater than the determination value (predetermined second current area fluctuation determination value), and the numerical value of the Ip2 excess frequency variable (ΣIp2 excess frequency) is the determination value. It is determined whether or not the condition that it is equal to or greater than (predetermined Ip2 number determination value) is satisfied. If an affirmative determination is made, the process proceeds to S720, and if a negative determination is made, the process proceeds to S730.

  The second current area variation determination value is a determination value determined to determine that the energization state of the second pump cell 41 has changed, and is determined based on actual measurement data using an actual NOx sensor. Can do. For example, the second current area variation determination value is derived from the factor (factor that varies the energization state of the second pump cell 41) determined in the second information sampling process (specifically, S690) described above. Can be determined based on the second pump current Ip2 (specifically, the integrated value of the waveform of the second pump current Ip2) when the energization state of f is changed.

  Further, the Ip2 number determination value is a determination value determined to determine that the energization state of the second pump cell 41 has changed, and can be determined based on actual measurement data using an actual NOx sensor. For example, the Ip2 number determination value is determined based on the state of energization of the second pump cell 41 due to the factor determined in the above-described second information sampling process (specifically, S690) (the factor that varies the energization state of the second pump cell 41). Can be determined based on the second pump current Ip2 (specifically, the number of times the second pump current Ip2 exceeds the Ip2 current excess determination value (determination value used in S670)).

  That is, in S710, processing is performed to determine whether the energization state of the second pump cell 41 has changed using the Ip2 area variable (ΣIp2 area) and the Ip2 excess count variable (ΣIp2 excess count).

  When an affirmative determination is made in S710 and the process proceeds to S720, in S720, it is determined that the Ip2 + wiring path is normal (in other words, there is no abnormality), and the path abnormality flag Fa indicating that the Ip2 + wiring path is in an abnormal state. Perform processing to reset.

  When a negative determination is made in S710 and the process proceeds to S730, in S730, the time required for the third information sampling process (S120) is set to a threshold (predetermined based on the numerical value of the measurement time variable that has started measurement in the third information sampling process. It is determined whether or not it is equal to or greater than the required time determination value. If an affirmative determination is made, the process proceeds to S750, and if a negative determination is made, the process proceeds to S740.

  The required time determination value is determined based on a generation period of a factor that changes the energization state of the second pump cell 41. In other words, the required time determination value is a time required for the third information sampling process (in other words, the required time for sampling the oxygen detection voltage Vs and the second pump current Ip2) in a range that does not cause an error in the state determination of the Ip2 + wiring path. Is set within the time.

  That is, when the time required for the third information sampling process is long, the long time is the cause of increasing the Ip2 area variable (ΣIp2 area) and the Ip2 excess count variable (ΣIp2 excess count). Therefore, even if the second pump current Ip2 actually fluctuates slightly, the Ip2 area variable and the Ip2 excess number variable may be large values. For this reason, when the time required for the third information sampling process is long, it may not be possible to accurately determine whether or not the energization state of the second pump cell 41 has changed.

For this reason, when an affirmative determination is made in S730 and the process proceeds to S750, the state determination of the Ip2 + wiring path is not performed in S750.
On the other hand, when a negative determination is made in S730 and the process proceeds to S740, in S740, it is determined that the Ip2 + wiring path is in an abnormal state, and a process of setting a path abnormality flag Fa indicating that the Ip2 + wiring path is in an abnormal state is performed. .

  When the route abnormality flag Fa is set, an abnormality handling process that is executed separately is started. In the abnormality handling process, a process for notifying the user that the connection path (Ip2 + wiring path) connecting the second pump cell 41 and the sensor control device 20 is in an abnormal state, and a specific gas obtained by the specific gas detection process A process for notifying that there is an error in concentration, a process for prohibiting the use of the specific gas concentration obtained in the specific gas detection process for other control processes, and the like are executed.

When one of the processes of S720, S740, and S750 ends, the process (third Ip2 + wiring determination process) ends, and the process shifts to the connection determination process again.
Thereafter, the process of S130 in the third embodiment ends, and the connection determination process of the third embodiment ends. The connection determination process is repeatedly executed at regular intervals while the sensor control device 20 is activated.

  Although illustration of actual measurement results is omitted, when the oxygen detection voltage Vs (in other words, the energization state of the oxygen concentration detection cell 36) greatly fluctuates, the second pump current Ip2 is followed so as to follow this. (In other words, the energization state of the second pump cell 41) has been found to fluctuate greatly from actual measurement data using an actual gas sensor. Such a change in the energized state occurs due to a change in the oxygen concentration of the measurement target gas introduced into the first measurement chamber 46, for example.

  For this reason, as in the connection determination process of this embodiment, it is determined whether or not the energization state of the oxygen concentration detection cell 36 varies based on the Vs area variable (ΣVs area) and the Vs excess frequency variable (ΣVs excess frequency). By performing (S690), the time when the energization state of the second pump cell 41 varies can be specified.

  Then, after it is determined that the energization state of the oxygen concentration detection cell 36 has fluctuated (Yes in S690) and the time when the energization state of the second pump cell 41 fluctuates is specified, the energization state of the second pump cell 41 is actually changed. By determining whether or not it has changed (S710), it can be determined whether or not the Ip2 + wiring path is in an abnormal state.

  As described above, the sensor control device 20 of the third embodiment, when it is determined that the energization state (oxygen detection voltage Vs) of the oxygen concentration detection cell 36 has fluctuated, Whether or not the connection state between the second pump cell 41 and the sensor control device 20 is a normal state or an abnormal state is determined depending on whether or not the 2 pump current Ip2) has fluctuated.

  For this reason, the sensor control apparatus 20 of 3rd Embodiment does not perform the signal input for abnormality detection with respect to the cell of NOx sensor 10, similarly to 1st Embodiment, but the 2nd pump cell 41 and the sensor control apparatus 20 Since it is possible to determine whether the connection state is normal or abnormal, there is an advantage that it is not necessary to interrupt gas detection when determining whether the connection state is normal or abnormal. .

  Therefore, according to the sensor control device 20 of the present embodiment, the connection between the NOx sensor 10 (specifically, the second pump cell 41) and the sensor control device 20 is performed without interrupting the detection operation of the specific gas concentration (NOx). It becomes possible to determine whether or not the state is abnormal.

  Further, since the sensor control device 20 makes a determination using the Vs area variable (ΣVs area) and the Vs excess count variable (ΣVs excess count) (S690), the energization state of the oxygen concentration detection cell 36 (oxygen detection voltage Vs). It is possible to appropriately determine whether or not has changed, and to appropriately determine when the energization state of the second pump cell 41 changes.

  Further, since the sensor control device 20 makes a determination using the Ip2 area variable (ΣIp2 area) and the Ip2 excess number variable (ΣIp2 excess number) (S710), the energization state of the second pump cell 41 (second pump current Ip2) Can be appropriately determined whether or not the connection state between the NOx sensor 10 (second pump cell 41) and the sensor control device 20 is abnormal.

  In the present embodiment, the control unit 30 that executes S120 (third information sampling process) corresponds to the energization state variation determination means, and the control unit 30 that executes S130 (third Ip2 + wiring determination process) determines the connection state. Corresponds to means.

  Further, the Vs area variable (ΣVs area) and the Vs excess count variable (ΣVs excess count) correspond to the reference cell fluctuation amount, and the Vs voltage area fluctuation determination value and the Vs frequency determination value correspond to the reference fluctuation determination value. Further, the Ip2 area variable (ΣIp2 area) and the Ip2 excess frequency variable (ΣIp2 excess frequency) correspond to the target cell fluctuation amount, and the second current area fluctuation determination value and the Ip2 frequency determination value correspond to the target fluctuation determination value.

  Next, as a fourth embodiment, determination is made using the internal resistance Rpvs of the oxygen concentration detection cell 36 as the energization state of the variation determination reference cell, and determination is performed using the second pump current Ip2 as the energization state of the abnormality determination target cell. An embodiment for performing connection path abnormality determination will be described.

  In the fourth embodiment, in detail, using an integrated value (area) of a waveform indicating the internal resistance Rpvs of the oxygen concentration detection cell 36 and an integrated value (area) of a waveform indicating the second pump current Ip2, Check the connection path for abnormalities. The basic configuration of the gas concentration measurement device of the fourth embodiment is the same as that of the gas concentration measurement device 1 of the first embodiment, and the processing content of the connection determination process executed by the control unit 30 is different. In the following description, the connection determination process will be mainly described. In addition, the component similar to 1st Embodiment among the components of 4th Embodiment is represented using the same code | symbol.

FIG. 10 is a flowchart showing the processing contents of the comprehensive connection determination process executed by the gas concentration measurement device 1 (specifically, the control unit 30 of the sensor control device 20) of the fourth embodiment.
The comprehensive connection determination process is a process for determining whether or not the connection path (wiring path) connecting the NOx sensor 10 and the sensor control device 20 is in an abnormal state.

  When the general connection determination process is started, first, in S810, an initialization process for internal variables used for the process is executed. Specifically, an initial value (such as 0) is substituted for an abnormality determination frequency variable (hereinafter also referred to as a determination count), and the path abnormality flag Fa is reset (0 is substituted), thereby setting the variable and flag. initialize.

  The abnormality determination frequency variable (determination count) is a variable for recording the number of times that the Ip2 + wiring path is determined to be abnormal in the determination process (S830) described later, and the path abnormality flag Fa is Ip2 + wiring path. Is a status flag indicating an abnormal state.

  In the next S820, it is determined whether or not the heater 12, other sensors, circuits, etc. are operating normally. If an affirmative determination is made, the process proceeds to S830, and if a negative determination is made, this process (general connection determination process). ) Ends.

  Note that whether or not the heater 12, other sensors, circuits, and the like are operating normally is determined using a determination result in a normal operation determination process that is separately executed in the sensor control device 20 or another control device. The As the normal operation determination process, a known method may be adopted as appropriate, and thus the description of the process is omitted.

  When an affirmative determination is made in S820 and the process proceeds to S830, in S830, the internal resistance Rpvs of the oxygen concentration detection cell 36 and the second pump current Ip2 are detected and accumulated, causing a factor that the energization state of the second pump cell 41 varies. And determining whether there is no abnormality in the connection path (Ip2 + wiring path) connecting the second pump cell 41 and the sensor control device 20 (Ip2 + wiring abnormality detection process) is executed. .

FIG. 11 is a flowchart showing the contents of the Ip2 + wiring abnormality detection process.
When the Ip2 + wiring abnormality detection process is started, first, in S910, it is determined whether or not the NOx sensor 10 is in an activated state. If it is in an activated state, an affirmative determination is made and the process proceeds to S120. If it is not in the activated state, a negative determination is made, and the same step is repeatedly executed until the activated state is reached.

  In S910, specifically, it is determined whether or not the determination temperature of the NOx sensor 10 determined based on the internal resistance Rpvs of the Vs cell 36 measured in the internal resistance measurement process is a predetermined activation temperature. Thus, it is determined whether or not the NOx sensor 10 is in an activated state.

  When an affirmative determination is made in S910 and the process proceeds to S920, a process of calculating an average value Ip2 # avg of the second pump current Ip2 is executed in S920. The average value Ip2 # avg is calculated based on the average value (movement) of the second pump current Ip2 during the detection period based on the accumulated data of the second pump current Ip2 detected during the predetermined detection period. There are calculation methods for calculating (average value).

  In next step S930, initialization processing of internal variables used for the processing is executed. Specifically, by substituting initial values (such as 0) for variables such as an Rpvs area variable (hereinafter also referred to as ΣRpvs area), an Ip2 area variable (hereinafter also referred to as ΣIp2 area), and a measurement time variable. Initialize each variable.

  Note that the Rpvs area variable (ΣRpvs area) is the amount of change in the energization state of the oxygen concentration detection cell 36 (specifically, the energization state according to the internal resistance Rpvs) (in other words, the internal resistance Rpvs of the oxygen concentration detection cell 36). Is a variable for recording a value corresponding to the integral value of the waveform. The Ip2 area variable (ΣIp2 area) is a value corresponding to the amount of change (in other words, the integrated value of the waveform of the second pump current Ip2) in the energization state of the second pump cell 41 (specifically, the second pump current Ip2). Is a variable for recording. The measurement time variable is a variable for recording the elapsed time.

  In the next step S940, the elapsed time is determined using the value of the measurement time variable, and the process waits until a predetermined sampling time elapses. A process of detecting the resistor Rpvs and the second pump current Ip2 is executed.

  In subsequent S950, the Rpvs area variable (ΣRpvs area) and the Ip2 area variable (ΣIp2) are calculated using the values of the internal resistance Rpvs and the second pump current Ip2 of the oxygen concentration detection cell 36 detected at the current sampling time (numerical value detection time). (Area) is updated.

  To update the Rpvs area variable, first, the difference value between the current detection value Rpvs (n) and the predetermined Rpvs target value in the internal resistance Rpvs of the oxygen concentration detection cell 36 is calculated, and the absolute value of the difference value is calculated. A value (currently calculated area) obtained by multiplying by 1 sampling time is calculated. Then, the Rpvs area variable is updated by adding the currently calculated area to the Rpvs area variable (ΣRpvs area).

  In addition, to update the Ip2 area variable, first, the difference value between the current detection value Ip2 (n) in the second pump current Ip2 and the average value Ip2 # avg obtained by the calculation of S920 is calculated, and the absolute value of the difference value is calculated. A value (currently calculated area) obtained by multiplying the value by one sampling time is calculated. Then, the Ip2 area variable is updated by adding the current calculated area to the Ip2 area variable (ΣIp2 area).

Furthermore, the measurement time variable is updated by adding one sampling time to the measurement time variable.
In next S960, it is determined whether or not the Rpvs area variable (ΣRpvs area) is equal to or greater than a threshold value (predetermined Rpvs area variation determination value). If an affirmative determination is made, the process proceeds to S970, and a negative determination is made. The process proceeds to S940 again.

  The Rpvs area variation determination value is a determination value determined for determining that the energization state of the oxygen concentration detection cell 36 has changed, and is determined based on actual measurement data using an actual NOx sensor. it can. For example, the Rpvs area variation determination value is an internal resistance when the energization state of the oxygen concentration detection cell 36 varies in association with a factor that varies the energization state of the second pump cell 41 (for example, a temperature change of the sensor body 11). Rpvs (specifically, an integrated value (area) of a waveform related to the internal resistance Rpvs) can be determined.

That is, in S960, based on the Rpvs area variable (ΣRpvs area), a process of determining whether or not a factor that causes the energization state of the second pump cell 41 to occur is performed.
When an affirmative determination is made in S960 and the process proceeds to S970, in S970, is the value of the Ip2 area variable (ΣIp2 area) obtained in the process of S950 equal to or greater than a determination value (predetermined second current area fluctuation determination value)? If a positive determination is made, the process proceeds to S980. If a negative determination is made, the process proceeds to S990.

  The second current area variation determination value is a determination value determined to determine that the energization state of the second pump cell 41 has changed, and is determined based on actual measurement data using an actual NOx sensor. Can do. For example, the second current area variation determination value is the second when the energization state of the second pump cell 41 varies due to the factor determined in S960 described above (the factor that varies the energization state of the second pump cell 41). It can be determined based on the pump current Ip2 (specifically, the integrated value of the waveform of the second pump current Ip2).

That is, in S970, a process of determining whether or not the energization state of the second pump cell 41 has changed using the Ip2 area variable (ΣIp2 area) is performed.
When an affirmative determination is made in S970 and the process proceeds to S980, in S980, it is determined that the Ip2 + wiring path is normal (in other words, there is no abnormality), and the abnormality determination frequency variable (determination count) is decremented by 1 (1 subtraction). ) Is executed. Note that the minimum value that can be taken by the abnormality determination number variable (determination count) is 0, and when the calculation result is less than 0, the numerical value of the abnormality determination number variable (determination count) is set to zero.

  When a negative determination is made in S970 and the process proceeds to S990, in S990, the time required for sampling processing of the internal resistance Rpvs and the second pump current Ip2 (repetition processing of S940 to S960) based on the numerical value of the measurement time variable updated in S950. Is greater than or equal to a threshold value (predetermined required time determination value). If an affirmative determination is made, the process proceeds to S1010, and if a negative determination is made, the process proceeds to S1000.

  The required time determination value is determined based on a generation period of a factor that changes the energization state of the second pump cell 41. That is, the required time determination value is a time within a range that does not cause an error in the determination of the state of Ip2 + wiring path as the required time of the sampling process (repetitive process from S940 to S960) of the internal resistance Rpvs and the second pump current Ip2. Is set.

  That is, when the time required for the sampling process of the internal resistance Rpvs and the second pump current Ip2 is long, the long time is one of the causes of increasing the Ip2 area variable (ΣIp2 area). Therefore, even if the second pump current Ip2 actually fluctuates only slightly, the Ip2 area variable may become a large value. For this reason, when the time required for the sampling process of the internal resistance Rpvs and the second pump current Ip2 is long, it may not be possible to accurately determine whether or not the energization state of the second pump cell 41 has changed. is there.

  For this reason, when an affirmative determination is made in S990 and the process proceeds to S1010, in S10100, the state determination of the Ip2 + wiring path is not performed, and the abnormality determination frequency variable (determination count) is not updated.

  On the other hand, when a negative determination is made in S990 and the process proceeds to S1000, in S1000, it is determined that the Ip2 + wiring path is in an abnormal state, and a process of incrementing (adding 1) the abnormality determination frequency variable (determination count) is executed. Note that the maximum value that can be taken by the abnormality determination number variable (determination count) is equal to a threshold value (determination number determination value) used in S840, which will be described later. The numerical value of the abnormality determination number variable (determination count) is set as the determination number determination value.

When any one of S980, S1000, and S1010 is completed, the present process (Ip2 + wiring abnormality detection process) is ended, and the process is again transferred to the general connection determination process.
Returning to the general connection determination process, in next step S840, it is determined whether or not the abnormality determination frequency variable (determination count) is equal to or greater than a threshold value (predetermined determination frequency determination value), and if an affirmative determination is made, the flow proceeds to S850. If a negative determination is made, the process proceeds to S820 again.

  The determination number determination value is a determination value determined for determining that the energization state of the second pump cell 41 has changed, and can be determined based on actual measurement data using an actual NOx sensor. For example, the determination number determination value is actually determined in S970 when the energization state of the second pump cell 41 varies due to the factor determined in S960 described above (the factor that varies the energization state of the second pump cell 41). It can be determined based on the affirmative measurement affirmative number (or a value obtained by multiplying the actual measurement affirmation number by a predetermined coefficient).

That is, in S840, processing for determining whether or not the energization state of the second pump cell 41 has changed using the abnormality determination frequency variable (determination count) is performed.
In the present embodiment, it is not immediately determined whether the Ip2 + wiring path is normal or abnormal based on the determination result in S970, but the number of times determined as an abnormal state (negative determination) in S970 (that is, negative determination) Based on the abnormality determination number variable (determination count)), it is determined whether the Ip2 + wiring path is normal or abnormal. Thus, by making a comprehensive determination based on a plurality of determination results, it is possible to reduce the influence of erroneous determination, and to accurately determine the state of the Ip2 + wiring path.

  When an affirmative determination is made in S840 and the process proceeds to S850, in S850, it is determined that the Ip2 + wiring path is in an abnormal state, and a process of setting a path abnormality flag Fa indicating that the Ip2 + wiring path is in an abnormal state is performed.

  When the route abnormality flag Fa is set, an abnormality handling process that is executed separately is started. In the abnormality handling process, a process for notifying the user that the connection path (Ip2 + wiring path) connecting the second pump cell 41 and the sensor control device 20 is in an abnormal state, and a specific gas obtained by the specific gas detection process A process for notifying that there is an error in concentration, a process for prohibiting the use of the specific gas concentration obtained in the specific gas detection process for other control processes, and the like are executed.

When the process of S850 is completed, the present process (total connection determination process) is completed.
The comprehensive connection determination process is repeatedly executed at regular intervals while the sensor control device 20 is activated.

  Although illustration of actual measurement results is omitted, when the internal resistance Rpvs of the oxygen concentration detection cell 36 (in other words, the energization state of the oxygen concentration detection cell 36) fluctuates greatly, this is followed. It has been found from actual measurement data using an actual gas sensor that the second pump current Ip2 (in other words, the energized state of the second pump cell 41) fluctuates greatly. Such a change in the energization state of the second pump cell 41 occurs due to, for example, a change in the temperature of the sensor element.

  Therefore, as in the connection determination process of the present embodiment, the second pump cell is determined by determining whether the energization state of the oxygen concentration detection cell 36 varies based on the Rpvs area variable (ΣRpvs area) (S960). It is possible to specify the time when the energization state 41 changes.

  Then, after it is determined that the energization state of the oxygen concentration detection cell 36 has changed (Yes in S960) and the time when the energization state of the second pump cell 41 changes is specified, the energization state of the second pump cell 41 is actually changed. By determining whether or not it has changed (S970), it can be determined whether or not the Ip2 + wiring path is in an abnormal state.

  As described above, the sensor control device 20 of the fourth embodiment, when it is determined that the energization state (internal resistance Rpvs) of the oxygen concentration detection cell 36 has fluctuated, the energization state of the second pump cell 41 (second Whether the connection state between the second pump cell 41 and the sensor control device 20 is a normal state or an abnormal state is determined depending on whether or not the pump current Ip2) has fluctuated.

  For this reason, the sensor control apparatus 20 of 4th Embodiment does not perform the signal input for abnormality detection with respect to the cell of NOx sensor 10, similarly to 1st Embodiment, but the 2nd pump cell 41 and the sensor control apparatus 20 Since it is possible to determine whether the connection state is normal or abnormal, there is an advantage that it is not necessary to interrupt gas detection when determining whether the connection state is normal or abnormal. .

  Therefore, according to the sensor control device 20 of the present embodiment, the connection between the NOx sensor 10 (specifically, the second pump cell 41) and the sensor control device 20 is performed without interrupting the detection operation of the specific gas concentration (NOx). It becomes possible to determine whether or not the state is abnormal.

  Further, since the sensor control device 20 makes a determination using the Rpvs area variable (ΣRpvs area) (S960), it can appropriately determine whether or not the energization state (internal resistance Rpvs) of the oxygen concentration detection cell 36 has changed. At the same time, it is possible to appropriately determine when the energization state of the second pump cell 41 varies.

  Furthermore, since the sensor control device 20 determines using the Ip2 area variable (ΣIp2 area) (S970), it appropriately determines whether or not the energization state (second pump current Ip2) of the second pump cell 41 has changed. In addition, it is possible to appropriately determine whether or not the connection state between the NOx sensor 10 (second pump cell 41) and the sensor control device 20 is abnormal.

  Further, the sensor control device 20 of the present embodiment determines whether or not the connection state of the Ip2 + wiring path is abnormal using the Ip2 area variable (ΣIp2 area) (S970), and determines that it is an abnormal state (No in S970). Based on the number of times determined (abnormality determination frequency variable (determination count)), it is finally determined whether or not the Ip2 + wiring path is abnormal (S840).

  That is, the sensor control device 20 of the present embodiment does not immediately determine whether the Ip2 + wiring path is normal or abnormal based on the single determination result in S970, but multiple determination results in S970. It is the structure which performs determination comprehensively based on. Since the comprehensive determination is performed as described above, the sensor control device 20 of the present embodiment can reduce the influence of the erroneous determination, and can accurately determine the state of the Ip2 + wiring path.

  In the present embodiment, the control unit 30 that executes the processes from S940 to S960 in the Ip2 + wiring abnormality detection process corresponds to the energization state variation determination means, and from S940, S950, and S970 to S1010 in the Ip2 + wiring abnormality detection process. The control unit 30 that executes the process from S840 to S850 in the process and the general connection determination process corresponds to a connection state determination unit.

  Further, the Rpvs area variable (ΣRpvs area) corresponds to the reference cell fluctuation amount, and the Rpvs area fluctuation determination value corresponds to the reference fluctuation determination value. Further, the Ip2 area variable (ΣIp2 area) and the abnormality determination frequency variable (determination count) correspond to the target cell fluctuation amount, and the second current area fluctuation determination value and the determination frequency determination value correspond to the target fluctuation determination value.

  Further, in the oxygen concentration detection cell 36, the internal resistance Rpvs is detected. The value of the internal resistance Rpvs is correlated with the temperature of the gas sensor (NOx sensor 10), and is used for detecting the temperature of the NOx sensor 10. It corresponds to a temperature detection cell. Therefore, in the present embodiment, the oxygen concentration detection cell 36 corresponds to a temperature detection cell.

As mentioned above, although several embodiment regarding this invention was described, this invention is not limited to the said embodiment, A various aspect can be taken.
For example, the connection determination process is not limited to a form that is repeatedly executed at regular intervals during activation of the sensor control device, and may be executed when a predetermined determination process execution condition is satisfied. Good.

  In the first embodiment, the second embodiment, and the third embodiment, it is configured to immediately determine whether the Ip2 + wiring path is normal or abnormal based on one determination result. As in the embodiment, it is possible to adopt a configuration in which determination is comprehensively made based on a plurality of determination results. By performing comprehensive determination in this manner, the influence of erroneous determination can be reduced, and the state determination of the Ip2 + wiring path can be realized with high accuracy.

  Furthermore, the combination of the state quantity used as the reference cell fluctuation amount and the state quantity used as the target cell fluctuation amount is not limited to the contents of the above embodiments. For example, an Rpvs area variable (ΣRpvs area) is used as the reference cell fluctuation amount, an Ip2 trajectory length integration variable (ΣIp2 trajectory length) is used as the target cell fluctuation amount, and a Vs area variable (ΣVs area) is used as the reference cell fluctuation amount. It is also possible to adopt a form in which the Ip2 trajectory length integration variable (ΣIp2 trajectory length) and the abnormality determination frequency variable (determination count) are used as the target cell fluctuation amount.

  Further, in the fourth embodiment, the temperature detection cell for detecting the temperature of the NOx sensor 10 is the oxygen concentration detection cell 36, but the first pump cell 31 or the second pump cell 41 is a temperature detection cell, and either The internal resistance Rpvs of the cells 31 and 41 may be detected, and the temperature of the gas sensor (NOx sensor 10) may be detected based on the value of the internal resistance Rpvs.

  Moreover, in the 1st-3rd embodiment, it determined with the electricity supply state of the 1st pump cell 31 having fluctuated (affirmation determination in S240 of 1st Embodiment, affirmation determination in S450 of 2nd Embodiment) Immediately after the affirmative determination in S690 of the third embodiment, the process proceeds to the process of S130 in the connection determination process. However, the change in the energization state of the second pump cell 41 is delayed from the change in the first pump cell 31. Follow and fluctuate. In consideration of this, the flow chart is configured so as to shift to the process of S130 in the connection determination process after a predetermined fixed time has elapsed after it is determined that the energization state of the first pump cell 31 has changed. May be.

  As an example, a modification of the information sampling process (S120) in the first embodiment will be described with reference to FIG. In the flowchart of FIG. 13, the processing of S210 to S240 is the same as the processing content of the first embodiment, and thus the description thereof will be omitted. The processing after the affirmative determination is made in S240 will be described below.

  If the result in S240 is affirmative, the process proceeds to S250. In S250, the elapsed time is determined using the value of the measurement time variable, and the process waits until one predetermined sampling time elapses, and one sampling time. When the time has elapsed, processing for detecting the second pump current Ip2 is executed.

  In subsequent S260, using the numerical value of the second pump current Ip2 detected at the current sampling timing (numerical value detection timing), processing for updating the Ip2 trajectory length integrated variable (ΣIp2 trajectory length) is performed following the processing of S230.

  In next S270, it is determined whether or not the second pump current Ip2 is detected by a plurality of samplings (for example, 3 samplings) after the affirmative determination in S240, and it is affirmed that the second pump current Ip2 is detected by a plurality of samplings. If it is determined, the process (information sampling process) is terminated, and the process proceeds to the connection determination process (S130). On the other hand, if a negative determination is made in S270, the process proceeds to S250 again.

  By making such a change, in the above-described embodiment, after it is determined that the energization state of the first pump cell 31 is fluctuating, the process proceeds to S130 in the connection determination process after a predetermined time has elapsed. A flowchart can be constructed.

  In the above-described embodiments, the sensor control device provided separately from the electronic control device (ECU) for comprehensively controlling each part of the automobile has been described. However, the electronic control device having the sensor control function ( (ECU) The present invention may be applied. That is, the electronic control unit (ECU) is not limited to the form connected to the gas sensor via the sensor control unit, but may be the form directly connected to the gas sensor.

  In an electronic control unit (ECU) that is directly connected to the gas sensor, a process for determining whether or not a connection path (wiring path) that connects the gas sensor and itself (electronic control unit) is in an abnormal state. (Connection determination processing) may be executed.

It is explanatory drawing which shows schematic structure of a gas concentration measuring apparatus provided with a sensor control apparatus. It is a circuit diagram which shows the circuit structure of a gas concentration measuring apparatus provided with a NOx sensor and a sensor control apparatus. It is a flowchart showing the processing content of the connection determination process. It is a flowchart showing the processing content of the information sampling processing. It is a flowchart showing the processing content of Ip2 + wiring determination processing. It is a flowchart showing the processing content of a 2nd information sampling process. It is a flowchart showing the processing content of 2nd Ip2 + wiring determination processing. It is a flowchart showing the processing content of a 3rd information sampling process. It is a flowchart showing the processing content of 3rd Ip2 + wiring determination processing. It is a flowchart showing the processing content of the general connection determination processing. It is a flowchart showing the processing content of Ip2 + wiring abnormality detection processing. It is a measurement result when the 1st pump current Ip1 and the 2nd pump current Ip2 are measured using an actual NOx sensor. It is a flowchart showing the processing content of the information sampling process as a modification of 1st Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Gas concentration measuring apparatus, 10 ... Gas sensor (NOx sensor), 11 ... Sensor main body, 12 ... Heater, 20 ... Sensor control apparatus, 30 ... Control part, 31 ... 1st pump cell (P1 cell), 32 ... 1st solid Electrolyte body 33... First inner electrode 34... First outer electrode 36... Oxygen concentration detection cell (Vs cell) 37... Solid electrolyte body for detection 38 38 Detection electrode 39 39 Reference electrode 41. 2nd pump cell (P2 cell), 42 ... 2nd solid electrolyte body, 43 ... 2nd inner side electrode, 44 ... 2nd outer side electrode, 46 ... 1st measurement chamber, 47 ... 2nd measurement chamber.

Claims (6)

In controlling a gas sensor having a plurality of cells each having a pair of porous electrodes formed on the surface of a solid electrolyte body, sensor control for controlling energization states in the plurality of cells in order to detect a specific gas contained in the measurement target gas A device,
Among the plurality of cells, the variation determination is performed with respect to a variation determination reference cell that is different from the abnormality determination target cell and whose own energization state varies in association with a factor that varies the energization state of the abnormality determination target cell. Energization state variation determining means for determining whether or not the energization state of the reference cell has changed;
In the case where the energization state of the variation determination reference cell is determined to be varied by the energization state variation determination means, and the energization state of the abnormality determination target cell is varied, the abnormality determination target cell and the sensor control Connection state determination for determining a connection state between the abnormality determination target cell and the sensor control device as an abnormal state when the connection state with the device is determined as a normal state and the energization state of the abnormality determination target cell does not vary Means,
A sensor control device comprising: The energization state variation determining means includes
A reference cell fluctuation amount indicating a fluctuation amount of the energization state in the fluctuation determination reference cell is compared with a reference fluctuation determination value determined in advance to determine that the energization state of the fluctuation determination reference cell has changed,
If the reference cell fluctuation amount is greater than or equal to the reference fluctuation determination value, it is determined that the energization state of the fluctuation determination reference cell has changed,
When the reference cell fluctuation amount is smaller than the reference fluctuation determination value, it is determined that the energization state of the fluctuation determination reference cell has not changed,
The sensor control apparatus according to claim 1. The connection state determination means includes
Comparing the target cell fluctuation amount indicating the fluctuation amount of the energization state in the abnormality determination target cell with a target fluctuation determination value determined in advance to determine that the energization state of the abnormality determination target cell has changed,
If the target cell fluctuation amount is equal to or greater than the target fluctuation determination value, it is determined that the energization state of the abnormality determination target cell has changed, and the connection state between the abnormality determination target cell and the sensor control device is normal. It is determined that
When the target cell fluctuation amount is smaller than the target fluctuation determination value, it is determined that the energization state of the abnormality determination target cell has not changed, and the connection state between the abnormality determination target cell and the sensor control device Is determined to be abnormal
The sensor control device according to claim 1 or 2, wherein The fluctuation determination reference cell is a temperature detection cell for detecting the temperature of the gas sensor;
The sensor control device according to any one of claims 1 to 3, wherein The gas sensor
A first measurement chamber for introducing the measurement target gas and adjusting the oxygen concentration of the measurement target gas to a target concentration to generate an adjusted measurement target gas;
A second measurement chamber into which the adjusted measurement target gas whose oxygen concentration is adjusted to a target concentration in the first measurement chamber is introduced, and
In the abnormality determination target cell, one of the pair of porous electrodes is disposed in the second measurement chamber, and an electrode corresponding to the concentration of NOx as a specific component contained in the adjusted measurement target gas Is configured to flow current between
The variation determination reference cell has one of the pair of porous electrodes disposed in the first measurement chamber,
The sensor control device according to any one of claims 1 to 4, wherein In the gas sensor, one of the pair of porous electrodes is disposed in the first measurement chamber, and the other of the porous electrodes is disposed in a reference atmosphere, depending on the oxygen concentration in the first measurement chamber. One of the oxygen detection cell that generates the inter-electrode voltage and the pair of porous electrodes is disposed in the first measurement chamber so that the inter-electrode voltage of the oxygen detection cell has a predetermined voltage value. And an oxygen pump cell for pumping out or pumping in oxygen of the measurement target gas introduced into the first measurement chamber,
The variation determination reference cell is either the oxygen pump cell or the oxygen detection cell;
The sensor control apparatus according to claim 5.

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