JP7232108B2 - sensor controller - Google Patents

Description

This specification discloses a technique related to a sensor control device that controls a gas sensor.

2. Description of the Related Art Conventionally, there is known a technique of detecting the concentration of exhaust gas generated by driving an internal combustion engine with a gas sensor. Patent Document 1 describes a gas sensor system that performs feedback control using a control constant that changes according to temperature because the frequency characteristics of the output of the gas sensor change according to temperature.

JP 2010-121951 A

By the way, in an internal combustion engine having a plurality of cylinders, the air-fuel ratio of the air-fuel mixture in the plurality of cylinders may become imbalanced due to malfunction of injectors, leakage of intake air, or the like. If the air-fuel ratios among the cylinders become imbalanced, the exhaust characteristics and the like deteriorate. Therefore, a configuration for detecting the air-fuel ratio imbalances among the cylinders is provided. When providing a configuration for detecting such an imbalance state, it is preferable to improve detection accuracy in order to suppress deterioration of exhaust characteristics and the like. However, in order to improve the detection accuracy of the imbalance state, it is necessary to improve the responsiveness of the imbalance component frequency. There is no problem.

The technique described in this specification was perfected based on the circumstances as described above, and aims to improve the detection accuracy of the imbalance state.

A sensor control device described in the present specification is a sensor control device for controlling a gas sensor that detects the concentration of exhaust gas emitted by driving an internal combustion engine having a plurality of cylinders, A control unit is provided for controlling the gas sensor by switching a first control constant for controlling the gas sensor to a second control constant when detecting an imbalance state of concentration of the exhaust gas.
A sensor control method described in the present specification is a sensor control method for controlling a gas sensor that detects the concentration of exhaust gas emitted by driving an internal combustion engine having a plurality of cylinders, A control procedure is provided for controlling the gas sensor by switching a first control constant for controlling the gas sensor to a second control constant when an imbalance state of the concentration of the exhaust gas is detected.
In order to improve the detection accuracy of the imbalance state of an internal combustion engine with multiple cylinders, the sensor control constant (PID, etc.) is always controlled with a set value that enhances the response of the high-frequency component, and the high-frequency signal of the sensor is controlled. In the case of amplification, since general noise is also a high-frequency component, the noise component is amplified, and problems such as malfunction of fuel feedback control and the like are feared.
On the other hand, according to the above configuration, when the imbalance state is detected, the control unit switches the first control constant to the second control constant to control the gas sensor. In comparison with the configuration in which the gas sensor is controlled using a single control constant that enhances the response of the high-frequency component both when the balance state is not detected and when the imbalance state is detected, errors such as fuel feedback control are reduced. It is possible to improve the detection accuracy when an imbalance state occurs while suppressing the operation.

The following aspects are preferred as embodiments of the technology described in this specification.
A storage unit for storing the first control constant and the second control constant is provided.
The second control constant is set so as to increase the detection sensitivity of the imbalance state more than the first control constant.
In this way, by switching the first control constant to the second control constant, it is possible to increase the detection sensitivity of the imbalance state.

The second control constant is set so that the gain of the frequency characteristic of the transfer function when using the second control constant is higher than the gain of the frequency characteristic of the transfer function when the first control constant is used. is set.

The second control constant lowers the phase of the frequency characteristic of the transfer function when the second control constant is used than the phase of the frequency characteristic of the transfer function when the first control constant is used. is set.

The control unit controls the gas sensor by switching the second control constant to the first control constant after the imbalance state is detected.

According to the technique described in this specification, it is possible to improve the detection accuracy of the imbalance state.

1 is a diagram showing a sensor system including a sensor control device according to an embodiment; FIG. Block diagram showing the electrical configuration of the sensor system Block diagram showing the relationship between the input and output of the feedback control of the gas sensor FIG. 10 is a diagram showing the frequency characteristics of the transfer function when the first control constant is used for the transfer function C; FIG. 10 is a diagram showing closed-loop frequency characteristics when the first control constant is used for the transfer function C; FIG. 11 is a diagram showing the frequency characteristics of the transfer function when the gain is increased using the second control constant for the transfer function C; The figure which shows the closed-loop frequency characteristic at the time of using the constant for 2nd control for the transfer function C. FIG. 10 is a diagram showing the frequency characteristics of the transfer function when the phase is lowered by using the second control constant for the transfer function C; The figure which shows the closed-loop frequency characteristic at the time of using the constant for 2nd control for the transfer function C. Flowchart showing processing of ECU Flowchart showing processing of the sensor control device

<Embodiment 1>
A sensor control device 50 of the present embodiment controls a gas sensor 30 that is mounted on a vehicle and detects the concentration of exhaust gas generated by driving the internal combustion engine 11 . As shown in FIG. 1, a sensor system 1 includes a gas sensor 30, an ECU 40 (Electronic Control Unit) as a processing device, and a sensor control device 50. The sensor control device 50 communicates between the gas sensor 30 and the ECU 40. connected by lines.

In this embodiment, the internal combustion engine 11 is, for example, a four-cylinder gasoline engine, and an intake pipe 12 through which air drawn from the outside flows and an exhaust pipe 13 through which exhaust gas generated by combustion of fuel flows are connected. It is On the upstream side of the injector 27 in the intake pipe 12, there are provided a throttle valve 16 that adjusts the amount of air taken into the internal combustion engine 11, and an intake pressure sensor 18 that detects the intake pressure of the taken air. The injector 27 is connected to the fuel tank TA, is provided in each of the plurality of cylinders on the upstream side of the internal combustion engine 11 , and injects fuel into the internal combustion engine 11 according to a control signal from the ECU 40 .

An EGR pipe 14 is connected between the intake pipe 12 and the exhaust pipe 13 . The EGR pipe 14 recirculates the exhaust gas from the exhaust pipe 13 to the intake pipe 12 . The EGR pipe 14 is provided with an EGR valve 15 , and the EGR valve 15 adjusts the flow rate of the exhaust gas flowing through the EGR pipe 14 . A water temperature sensor 20 for detecting the water temperature of the cooling water 19 is arranged near the internal combustion engine 11, and a rotation angle sensor 23 for outputting a pulse signal at each predetermined crank angle is provided on the crankshaft 22 of the internal combustion engine 11. is connected. A rotation angle sensor 23 detects the rotation speed of the internal combustion engine 11 . Detection signals from the intake pressure sensor 18 , the water temperature sensor 20 and the rotation angle sensor 23 are output to the ECU 40 . Further, the opening degrees of the EGR valve 15 and the throttle valve 16 are controlled by control signals from the ECU 40 . Downstream of the gas sensor 30 in the exhaust pipe 13, a three-way catalyst (not shown) is provided for removing harmful substances contained in the exhaust gas.

The gas sensor 30 is a so-called linear lambda sensor, is attached to the exhaust pipe 13 on the downstream side of the internal combustion engine 11, and detects the oxygen concentration in the exhaust gas over a wide range. The ECU 40 includes a CPU (Central Processing Unit), ROM, and RAM. The CPU executes programs stored in the ROM, receives detection signals from various sensors, and outputs control signals for operating the injector 27 and the like. Output.

An electrical configuration of the sensor system 1 will be described with reference to FIG.
As shown in FIG. 2 , the gas sensor 30 includes a pump cell 31 , an electromotive force cell 32 and a heater 33 . Each of the pump cell 31 and the electromotive force cell 32 has an oxygen ion conductive solid electrolyte body formed in a plate shape from partially stabilized zirconia, and electrodes formed mainly of platinum on each of its front and back surfaces, The oxygen concentration is detected by a so-called limiting current method. Since the pump current Ip flowing between the electrodes of the pump cell 31 increases as the oxygen concentration increases, the limit current of the pump current Ip increases as the oxygen concentration in the exhaust gas increases (the air-fuel ratio becomes leaner). , the limit current decreases as the oxygen concentration in the exhaust gas becomes lower (the air-fuel ratio becomes richer). Therefore, the oxygen concentration in the exhaust gas can be detected by measuring the pump current Ip.

The heater 33 is made of a material mainly composed of alumina, and has a heating resistor inside which is made of a material mainly composed of platinum. The heater 33 is controlled by electric power supplied from the sensor control device 50 so that the temperatures of the electromotive force cell 32 and the pump cell 31 become the activation temperature. becomes a state in which it is possible to detect the concentration of

The ECU 40 includes a drive state determination section 41 , an imbalance detection section 42 and an input/output section 45 . The drive state determination unit 41 determines whether or not the state related to the drive of the internal combustion engine 11 is within a predetermined variation range. Specifically, it is determined whether or not the fluctuation range of the drive state of the internal combustion engine itself and the fluctuation range of the devices that operate according to the drive of the internal combustion engine 11 are smaller than a predetermined value stored in advance in the memory. to decide. In this embodiment, the drive state determination unit 41 is connected to the rotation angle sensor 23 (FIG. 1), and determines whether or not the variation in the rotation speed detected by the rotation angle sensor 23 is within a predetermined variation range. to decide. For example, a state related to driving of the internal combustion engine 11 when the amount of change in the rotation speed per unit time detected by the rotation angle sensor 23 is within a range of predetermined upper and lower limit values stored in advance in the memory of the ECU 40. is within a predetermined variation range. Whether or not the state related to the driving of the internal combustion engine 11 is within the predetermined fluctuation range is not limited to the fluctuation of the rotational speed of the rotation angle sensor 23 . For example, fluctuations in the intake pressure of the intake pipe 12 detected by the intake pressure sensor 18, fluctuations in the temperature of the cooling water 10 detected by the water temperature sensor 20, fluctuations in the fuel injection amount injected by the injector 27, EGR (exhaust gas regeneration) A determination may be made as to whether or not fluctuations in the exhaust gas recirculation rate are within a predetermined fluctuation range. It can be determined whether it is within the range or not.

The imbalance detection unit 42 includes an imbalance diagnosis unit 43 and an imbalance determination unit 44 . The imbalance diagnosis unit 43 executes fast Fourier transform (FFT) processing using sampling data of the detection signal that is detected by the gas sensor 30 and input from the sensor control device 50, and determines the 0.5 order frequency component intensity and 1 Calculate the FFT intensity of the next frequency component intensity. The 0.5th order frequency component and the 1st order frequency component are frequency components corresponding to 1/2 and 1 times the frequency [Hz] corresponding to the engine speed [rpm]. Increasing the responsiveness of the gas sensor 30 tends to increase noise during detection of an imbalance state, but the imbalance detection diagnosis can be performed in a relatively short time, and the problem of noise is less likely to occur. Specifically, in this embodiment, the imbalance diagnosis process can be performed, for example, in about 20 cycles (=40 rotations). , 20 cycles, the imbalance condition can be detected in 1/(3000/60)×40=0.8 s.

The imbalance determination unit 44 compares the FFT intensity output from the imbalance diagnosis unit 43 with a predetermined threshold stored in advance in a memory, determines whether or not there is an imbalance state, and determines whether or not the determined imbalance state exists. Output information.

The sensor control device 50 is realized by an ASIC (application specific integrated circuit), and as shown in FIG. It includes a unit 55 (an example of a “control unit”), a current DA conversion unit 58 , an Rpvs calculation unit 59 , a duty calculation unit 60 , a heater driving unit 61 and an input/output unit 62 . The sensor control device 50 also includes a pump current terminal TIp electrically connected to the positive electrode side of the pump cell 31, a common terminal TCOM electrically connected to the negative electrode side of the electromotive force cell 32 and the positive electrode side of the pump cell 31, A voltage detection terminal TVs electrically connected to the negative electrode side of the electromotive force cell 32 and a heater terminal TH are provided.

The reference voltage generator 51 generates a reference voltage applied to the common terminal TCOM. In this embodiment, the reference voltage is 2.7V. The current supply unit 52 supplies a very small current Icp to the electromotive force cell 32 via the voltage detection terminal TVs, thereby moving oxygen ions to the reference electrode side (not shown) and creating an oxygen concentration atmosphere as a reference for gas detection. generated at the reference electrode. Thereby, the reference electrode functions as an oxygen reference electrode that serves as a reference for detecting the oxygen concentration in the exhaust gas. Furthermore, the current supply unit 52 supplies a pulse current Irpvs for detecting the internal resistance value of the electromotive force cell 32 to the electromotive force cell 32 via the voltage detection terminal TVs.

The AD converter 53 converts the voltage value of the analog signal input from the voltage detection terminal TVs into a digital signal, and outputs the digital signal to the PID controller 55 and the Rpvs calculator 59 . Based on the digital signal input from the AD conversion unit 53, the PID control unit 55 adjusts the voltage difference between the voltage at the voltage detection terminal TVs and the voltage at the common terminal TCOM to a preset target voltage (eg, 450 mV). Feedback control is performed to adjust the pump current Ip so that

The PID control unit 55 includes a storage unit 56 in which the first control constant PID1 and the second control constant PID2 are stored. The first control constant PID1 and the second control constant PID2 are transfer function control constants used for PID control (Proportional-Integral-Differential Controller) for controlling the gas sensor 30. stored in The relationship between the first control constant PID1 and the second control constant PID2 is such that when the transfer function for controlling the gas sensor 30 is used, the second control constant PID2 is higher than the first control constant PID1. It is a control constant that increases the detection sensitivity of an imbalanced state of air-fuel ratios among a plurality of cylinders. Specifically, in this embodiment, the value of the second control constant PID2 is set so that the gain of the frequency characteristic is higher than that of the first control constant PID1.

More specifically, as shown in FIG. 3, the sensor control device 50 performs feedback control using a transfer function C(s) with a control circuit on the gas sensor 30 as a controlled object.
In addition, the transfer function C PID (s) of the PID control (PID calculation) portion of the transfer function C ₍ s) in FIG.
C _PID (s)=K _P +K _I /s+K _D s=K _P {1+(1/T _I s)+T _D s}
, K _P : constant of proportionality, KI : constant of integration, K _D : differential constant, s: Laplace operator, _TI = K _P /K _I : integral time, _{TD =} K _D /K _P : differential time It is said that
The first control constant PID1 and the second control constant PID2 are the proportionality constant K _{P and} the integral The constant K _I and the differential constant K _D are switched to different constants (values).

As shown in FIG. 2, the PID control unit 55 changes the transfer function C _PID (s) used for PID control (PID calculation) according to control constant switching instruction signals S1 and S3 input from the ECU 40. The first control constant PID1 and the second control constant PID2 are switched. Here, FIGS. 4A, 5A, and 6A show frequency characteristics of the transfer function C, and FIGS. 4B, 5B, and 6B show closed-loop frequency characteristics. In each figure, the solid line indicates the gain, and the broken line indicates the phase. 4A and 4B show the frequency characteristics and closed-loop frequency characteristics of the transfer function C when the first control constant PID1 is used. 6A and 6B show the frequency characteristics and closed-loop frequency characteristics of the transfer function C when using the second control constant PID2 set to . 4 shows frequency characteristics and closed-loop frequency characteristics of the transfer function C when the second control constant PID2 is used.

As shown in FIG. 5A, when the second control constant PID2 that increases the gain of the frequency characteristic of the transfer function more than the first control constant PID1 is used (as shown by the dashed arrow in FIG. 5A, the graph G1A in FIG. 4A In the graph G21A) in which the gain is increased by one scale, the response of the graph G21B is improved compared to the graph G1B of FIG. 4B, as shown in the portion surrounded by the broken line in FIG. 5B. Therefore, by using the second control constant PID2 for the transfer function, it can be seen that the detection sensitivity of the imbalance state can be improved more than when the first control constant PID1 is used.

Here, in order to increase the detection sensitivity of the imbalance state, the configuration is not limited to setting the second control constant PID2 so as to increase the gain of the frequency characteristic of the transfer function. Specifically, for example, as another embodiment, as shown in FIGS. 6A and 6B, the second control constant PID2 is set to lower the phase of the frequency characteristics of the transfer function than the first control constant PID1. When the set second control constant PID2 is used (as indicated by the dashed arrow in FIG. 6A, the graph P22A in which the phase is lowered by 0.5 from the graph P1A in FIG. 4A), FIG. As shown in (the portion surrounded by the dashed line), the responsiveness of graph P22B is improved with respect to graph P1B of FIG. 4B. It can be seen that using the second control constant PID2 that is set to lower the phase in this way also enhances the detection sensitivity of the imbalance state. Note that when the phase of the frequency characteristic of the transfer function is lowered, as shown in FIG. Since there is a possibility that the gas sensor control system oscillates due to the occurrence of excessively large portions, it is more preferable to use the second control constant PID2 set to increase the gain of the frequency characteristic of the transfer function described above.

The current DA converter 58 converts the current value of the digital signal input from the PID controller 55 into a pump current Ip. The Rpvs calculation unit 59 performs calculation for calculating the internal resistance value Rpvs of the electromotive force cell 32 based on the digital signal input from the AD conversion unit 53 while the current supply unit 52 is supplying the pulse current Irpvs. , and outputs a digital signal indicating this internal resistance value Rpvs to the duty calculation unit 60 .

Based on the digital signal input from the Rpvs calculation unit 59, the duty calculation unit 60 calculates the amount of heat generated by the heater 33 required to maintain the temperature of the electromotive force cell 32 at a preset target temperature. Then, the duty calculation unit 60 calculates the duty ratio of the electric power supplied to the heater 33 based on the calculated amount of heat generated by the heater 33, and outputs a PWM (Pulse Width Modulation) control signal according to the calculated duty ratio to the heater driving unit. 61. The heater drive section 61 causes the heater 33 to generate heat based on the PWM control signal input from the duty calculation section 60 .

Processing of the ECU 40 will be described with reference to FIG.
In the ECU 40, the rotation angle sensor 23 constantly inputs a detection signal corresponding to the rotation speed to the drive state determination section 41. FIG. As shown in FIG. 7, the driving state determination unit 41 of the ECU 40 determines whether or not the variation in the number of rotations per unit time is within a predetermined range (the driving state is within a predetermined variation range) based on the input detection signal. (S11). If the variation in the rotation speed is not within the predetermined variation range ("NO" in S11), the variation in the drive state such as the fuel injection amount is large, and it is assumed that the detection of the imbalance state of the plurality of cylinders is not performed. Even if this is done, the imbalance state cannot be detected with high precision, so the process is terminated.

On the other hand, if the variation in the number of revolutions per unit time is within the predetermined range ("YES" in S11), the sensor control device 50 is notified of the transfer function set to the sensor control device 50. An instruction signal S1 for instructing switching from the constant PID1 for the first control to the constant PID2 for the second control is output (S12).

Next, it waits to receive a completion signal S2 for switching the control constant of the transfer function from the sensor control device 50 ("NO" in S13). When the transfer function control constant switching completion signal S2 is received from the sensor control device 50 ("YES" in S13), an imbalance diagnosis calculation is performed (S14). In the imbalance diagnosis calculation, the imbalance detection unit 42 executes fast Fourier transform processing based on the detection signal of the air-fuel ratio detected by the gas sensor 30 to obtain the 0.5 order frequency component strength and the 1st order frequency component strength. calculate.

Next, the calculated 0.5th-order frequency component intensity and 1st-order frequency component intensity are compared with thresholds stored in advance in the memory (S15). If the 0.5th order frequency component intensity and the 1st order frequency component intensity are equal to or greater than the threshold ("YES" in S15), there is a high possibility that an air-fuel ratio imbalance has occurred between a plurality of cylinders. , a detection signal indicating the imbalance state is output to the outside (S16). When a detection signal indicating an imbalance state is output, for example, an external warning light (not shown) can be displayed. On the other hand, if the 0.5th order frequency component intensity and the 1st order frequency component intensity are not equal to or greater than the threshold ("NO" in S15), no imbalance state detection signal is output (or a detection signal indicating that the imbalance state is not present). ).
Next, an instruction signal S3 for switching the second control constant PID2 of the transfer function to the first control constant PID1 is output to the sensor control device 50 (S17), and the process ends. After switching to the first control constant PID1 in the sensor control device 50, a signal S4 indicating completion of the switching may be received from the sensor control device 50 and the process may be terminated.

Processing of the sensor control device 50 will be described with reference to FIG.
As shown in FIG. 8, the sensor control device 50 uses the first control constant PID1 as a transfer function to control the gas sensor 30 until a control constant switching instruction signal S1 is received from the ECU 40 ("NO" in S21). Perform feedback control. When a control constant switching instruction signal S1 is received from the ECU 40 ("YES" in S21), the second control constant PID2 is read from the storage unit 56, and the first control constant PID1 of the transfer function is changed to the second control constant PID1. The constant PID2 is switched (S22), and a signal S2 is output to the ECU 40 to indicate that the switching has been completed. At this time, the storage unit 56 may store information about the currently set control constants (for example, information indicating that PID2 is used and information about the changed transfer function).

Then, the gas sensor 30 is controlled using the second control constant PID2 until an instruction signal S3 for switching back the control constant is received from the ECU 40 ("NO" in S23). When an instruction signal S3 for switching back the control constant is received from the ECU 40 ("YES" in S23), the second control constant PID2 of the transfer function is switched to the first control constant PID1 (S24), and the process ends. do. After switching from the second control constant PID2 to the first control constant PID1, a signal S4 may be output to the ECU 40 to indicate that the switching has been completed.

According to this embodiment, the following functions and effects are obtained.
The sensor control device 50 of the present embodiment is a sensor control device 50 that controls the gas sensor 30 that detects the concentration of the exhaust gas emitted by driving the internal combustion engine 11 having a plurality of cylinders, and detects the concentration of the exhaust gas between the plurality of cylinders. When the gas concentration imbalance state is detected, the PID control unit 55 (control unit ).
In order to improve the accuracy at the time of detection of the imbalance state of the internal combustion engine 11 having a plurality of cylinders, the sensor control constant (PID, etc.) is always controlled with a set value that enhances the response of the high-frequency component, and the high-frequency signal of the sensor is controlled. In the case of amplifying , general noise is also a high-frequency component, so the noise component is amplified, and there is concern about problems such as malfunction of fuel feedback control or the like.
On the other hand, according to the above embodiment, when the imbalance state is detected, the PID control unit 55 switches the first control constant PID1 to the second control constant PID2 to control the gas sensor 30. For example, compared to a configuration in which the gas sensor 30 is controlled using a single control constant that enhances the response of high-frequency components both in normal times (when an imbalance state is not detected) and when an imbalance state is detected, It is possible to improve detection accuracy when an imbalance state occurs while suppressing malfunction of fuel feedback control or the like.

Further, the second control constant PID2 is set so as to increase the detection sensitivity of the imbalance state more than the first control constant PID1.
By doing so, it is possible to increase the detection sensitivity of the imbalance state by switching the first control constant PID1 to the second control constant PID2.

After the imbalance state is detected, the PID control unit 55 switches the second control constant PID2 to the first control constant PID1 to control the gas sensor 30 .
By doing so, it is possible to suppress deterioration in the accuracy of fuel feedback control or the like due to an increase in the usage time of the second control constant PID2.

Further, the PID control unit 55 switches the first control constant PID1 to the second control constant PID2 to control the gas sensor 30 when the state of the internal combustion engine 11 is within a predetermined fluctuation range.
In this way, the effect on the fuel feedback control of the internal combustion engine 11 and the like can be reduced compared to a configuration in which the control constant is switched when the state related to the driving of the internal combustion engine 11 varies greatly. be able to.

<Other embodiments>
The technology described in this specification is not limited to the embodiments described in the above description and drawings, and for example, the following embodiments are also included in the technical scope of the technology described in this specification.
(1) The gas sensor 30 is a gas sensor composed of two cells, the pump cell 31 and the electromotive force cell 32, but is not limited to this, and is a one-cell gas sensor in which the pump cell and the electromotive force cell constitute one sensor element. may be used.

(2) A part of the configuration implemented by software in the above embodiments may be replaced with hardware. For example, the PID control unit 55 is configured to perform PID calculations by digital processing, but is not limited to this. may be For example, for an analog circuit, a first resistor capable of generating a first control constant PID1 and a second resistor having a resistance value different from that of the first resistor and capable of generating a second control constant PID2 are provided. The first control constant PID1 and the second control constant PID2 may be switched by switching one of the first resistor and the second resistor. Further, the calculation by the PID control unit 55 does not have to use all of the PID, and for example, P calculation, PI calculation, PD calculation, etc. may be performed. Also, a constant other than the PID may be used as the control constant.

(3) Switching between the first control constant PID1 and the second control constant PID2 is performed when an imbalance state is detected regardless of changes in the state related to the driving of the internal combustion engine 11. good too. For example, the configuration may be such that switching between the first control constant PID1 and the second control constant PID2 is performed at a predetermined timing (time) at which an imbalance state is detected.

(4) Although an embodiment using an oxygen sensor as the gas sensor 30 has been described, a gas sensor that detects gases other than oxygen (for example, NOx, etc.) may be used.
(5) The storage unit 56 is configured to be provided in the PID control unit 55, but is not limited to this, and stores the first control constant PID1 and the second control constant PID2 other than the PID control unit 55 It is good also as a structure provided with a memory|storage part.

(6) Although the sensor control device 50 and the ECU 40 are configured separately, part or all of the circuit configuration of the ECU 40 may be included in the sensor control device.

1: sensor system, 11: internal combustion engine, 30: gas sensor, 40: ECU, 42: imbalance detection unit, 50: sensor control device, 55: PID control unit (control unit), 56: storage unit, PID1: first Control constant, PID2: second control constant

Claims (7)

A sensor control device for controlling a gas sensor that detects the concentration of exhaust gas emitted by driving an internal combustion engine having a plurality of cylinders,
Control for controlling the gas sensor by switching a first control constant for controlling the gas sensor to a second control constant when detecting an imbalance state of the concentration of the exhaust gas among the plurality of cylinders. having a department ,
The gas sensor comprises a pump cell and an electromotive force cell,
The gas sensor detects the concentration of exhaust gas based on the pump current flowing through the pump cell,
The control unit feedback-controls the pump current so that the voltage applied to the electromotive force cell becomes a preset target voltage,
The sensor control device , wherein the first control constant and the second control constant are constants used for the feedback control . 2. The sensor control device according to claim 1, further comprising a storage unit for storing said first control constant and said second control constant. 3. The sensor control device according to claim 1, wherein the second control constant is set to increase detection sensitivity of the imbalance state more than the first control constant. The second control constant is set so that the gain of the frequency characteristic of the transfer function when using the second control constant is higher than the gain of the frequency characteristic of the transfer function when the first control constant is used. 4. The sensor control device according to any one of claims 1 to 3, wherein the sensor control device is set. The second control constant lowers the phase of the frequency characteristic of the transfer function when the second control constant is used than the phase of the frequency characteristic of the transfer function when the first control constant is used. 4. The sensor control device according to any one of claims 1 to 3, wherein the sensor control device is set. 6. The control unit according to any one of claims 1 to 5, wherein after the imbalance state is detected, the control unit switches the second control constant to the first control constant to control the gas sensor. A sensor control device according to any one of the preceding claims. A sensor control method for a sensor control device for controlling a gas sensor that detects the concentration of exhaust gas emitted by driving an internal combustion engine having a plurality of cylinders, the sensor control method comprising an imbalance state of the concentration of the exhaust gas among the plurality of cylinders. a control procedure for controlling the gas sensor by switching a first control constant for controlling the gas sensor to a second control constant when the detection of
The gas sensor comprises a pump cell and an electromotive force cell,
The gas sensor detects the concentration of exhaust gas based on the pump current flowing through the pump cell,
The sensor control device feedback-controls the pump current so that the voltage applied to the electromotive force cell becomes a preset target voltage,
The sensor control method , wherein the first control constant and the second control constant are constants used for the feedback control .

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