JP2018128354A - Sensor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor controller which can resume detection of a state quantity by a sensor quickly when there was generated an abnormal communication between the sensor controller and an external apparatus and the abnormal communication was thereafter removed.SOLUTION: A sensor controller 5 includes: a sensor 8 having an element unit and a heater unit; a sensor driving unit; a heater control unit; an information communication unit; and a communication abnormality detection unit. The sensor controller is formed to keep a heater control state before an abnormal communication was detected and control the heater unit, instead of immediately shifting the heater control state to another control unit (stop of heater conduction), when the communication abnormality detection unit detects an abnormal communication. The sensor controller can keep the active state of the sensor (element unit) even if there is an abnormal communication with an external apparatus, and can resume detection by the sensor quickly after the abnormal communication was removed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sensor control device that controls a sensor having an element portion and a heater portion.

A sensor control device that controls a sensor that detects various state quantities (gas concentration, temperature, etc.) is known (Patent Document 1).
The sensor has an element part and a heater part. The element portion includes at least one cell including a solid electrolyte body and a pair of electrodes provided on the solid electrolyte body. The heater unit is configured to heat the solid electrolyte body of the cell.

  The sensor control device is connected to an external device (for example, an engine control device) via a communication line (for example, a transmission cable), and transmits and receives control information related to sensor control. Examples of control information related to sensor control include information (such as detection values) transmitted from the sensor control device to an external device, and information (such as control command values) transmitted from the external device to the sensor control device. It is done.

JP 2010-160011 A

However, in the above conventional sensor control device, there is a case where communication abnormality occurs in communication with the external device and information transmission / reception with the external device becomes impossible.
When such a communication abnormality occurs, the control information from the external device cannot be received, and therefore the sensor control state may become inappropriate. In order to suppress the occurrence of such a situation, a countermeasure of stopping the sensor control can be considered.

  However, when the state in which the sensor control is stopped is prolonged, the temperature of the element portion is lowered, and the sensor may be in an inactivated state (a state quantity cannot be detected). When the sensor is deactivated, after the communication abnormality is resolved and the sensor control is resumed, until the sensor (specifically, the element unit) is activated (a state quantity can be detected). This causes a problem that it takes time.

  Therefore, the present disclosure provides a sensor control device that can quickly resume state quantity detection using a sensor when a communication error occurs in communication between the sensor control device and an external device, and then the communication error is resolved. The purpose is to provide.

One aspect of the present disclosure is a sensor control device that controls a sensor including an element unit and a heater unit, and includes a sensor driving unit, a heater control unit, an information communication unit, and a communication abnormality detection unit.
The element portion includes at least one cell including a solid electrolyte body and a pair of electrodes provided on the solid electrolyte body. The heater unit is configured to heat the solid electrolyte body.

  The sensor driving unit is connected to the element unit and configured to energize the cell to drive the element unit. The heater control unit is configured to control the heater unit in one energization mode instructed by an external device among the plurality of energization modes. The information communication unit is configured to transmit / receive information including at least control information related to sensor control to / from an external device.

  A sensor control device including such a heater control unit performs heater control according to a command from an external device by executing heater control based on the received communication mode in a situation where the communication mode of heater control can be received. Although it can be realized, heater communication instruction information cannot be received from an external device when a communication error occurs.

  Therefore, the sensor control device includes a communication abnormality detection unit that detects a communication abnormality with an external device. The heater control unit is configured to control the heater unit while maintaining the heater control state in the energization mode before the communication abnormality is detected when the communication abnormality detection unit detects the communication abnormality. Yes.

  In this sensor control device, when the communication abnormality detection unit detects a communication abnormality, the heater control state is not immediately shifted to another control state (for example, heater energization is stopped), but a communication abnormality is detected. The heater unit is controlled while maintaining the previous heater control state. For this reason, this sensor control device can maintain the activated state of the sensor (element unit) even when a communication abnormality with an external device occurs, and uses the sensor early after the communication abnormality is resolved. You can resume detection.

  Therefore, the sensor control device can quickly resume the state quantity detection using the sensor when the communication abnormality occurs in the communication with the external device and the communication abnormality is subsequently eliminated.

  The control information related to sensor control is, for example, information (detection value or the like) transmitted from the sensor control device to the external device, or information (control command value or the like) transmitted from the external device to the sensor control device. Is mentioned.

  Next, the sensor control device of the present disclosure may include a control abnormality detection unit that detects a control abnormality including at least a wiring abnormality in a wiring connecting the sensor driving unit and the element unit. When the control abnormality detection unit detects a control abnormality, the heater control unit may change the control state of the heater unit to the abnormal state control state regardless of whether the communication abnormality detection unit detects a communication abnormality. Good.

  In this sensor control device, the heater controller is in a normal heater control state, not a communication abnormality, and the control abnormality detector is in either case of continuing the heater control state before the communication abnormality is detected. When a control abnormality is detected, the control state of the heater unit is shifted to an abnormal time control state. By shifting the control state of the heater unit to the abnormal state control state in this way, it is possible to suppress the normal control of the heater unit from being continued in a state where the control abnormality has occurred. Thereby, it is possible to prevent the heater unit from being damaged due to the normal control of the heater unit being continued.

  The wiring abnormality includes, for example, a short circuit abnormality (ground short circuit, power supply short circuit, etc.), a disconnection abnormality, and the like. Moreover, the stop of the control of the heater unit means, for example, a stop of energization to the heater.

  Next, in the sensor control device of the present disclosure including the control abnormality detection unit, the heater control unit is configured to set the application voltage to the heater unit to a predetermined abnormality application voltage set in advance in the abnormality control state. There may be.

  In this way, by setting the voltage applied to the heater unit to a predetermined abnormal voltage applied in advance, it is possible to suppress feedback control from spreading and improper application voltage to the heater unit, and inappropriate It is possible to suppress breakage of the heater part due to an applied voltage. Here, setting in advance means, for example, setting a predetermined value as an initial value for the applied voltage at the time of abnormality in the storage unit (EEPROM or the like), or before a communication abnormality occurs (that is, when communication is normal). There is also a method of setting a value received from an external device as an abnormal voltage applied.

  The abnormality applied voltage is a voltage set within a voltage range that does not cause damage to the heater section. For example, a 50% value with respect to the maximum value (allowable maximum voltage value) of the voltage that can be applied to the heater section, 30 % Value, 10% value, etc. may be used.

It is a whole lineblock diagram of a gas detection system provided with a sensor control device. It is a flowchart showing the processing content of heater control switching processing.

Hereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings.
In addition, this indication is not limited to the following embodiment at all, and it cannot be overemphasized that various forms may be taken as long as it belongs to the technical scope of this indication.

[1. First Embodiment]
[1-1. overall structure]
FIG. 1 is an overall configuration diagram of a gas detection system 1 as an embodiment of the present disclosure.

The gas detection system 1 is used for the purpose of detecting a specific gas (oxygen in the present embodiment) in the exhaust gas of an internal combustion engine, for example.
The gas detection system 1 includes a gas detection device 3 and a gas sensor 8.

The gas detection device 3 includes a sensor control device 5 and an engine control device 7.
The sensor control device 5 drives and controls the gas sensor 8 to detect the oxygen concentration in the exhaust gas, and notifies the engine control device 7 of the detected oxygen concentration. Details of the sensor control device 5 will be described later.

  The engine control device 7 is a microcontroller that executes various control processes for controlling the internal combustion engine. As one of the various control processes, the air-fuel ratio control of the internal combustion engine is performed using the oxygen concentration detected by the sensor control device 5. I do.

  The gas sensor 8 is an oxygen sensor that detects oxygen. The gas sensor 8 is provided in an exhaust pipe of an internal combustion engine (engine) and detects the oxygen concentration in the exhaust gas over a wide area, and is also called a linear lambda sensor. The gas sensor 8 includes a sensor element 9 and a heater 26.

The sensor element 9 includes a pump cell 14. The pump cell 14 has an oxygen ion conductive solid electrolyte body 15 formed of partially stabilized zirconia (ZrO ₂ ), and a pair of porous electrodes 16 mainly formed of platinum on the front and back surfaces thereof. doing.

  The heater 26 includes a heating resistor that generates heat when energized from the outside. The heater 26 is provided to heat the sensor element 9 (particularly, the pump cell 14) and to activate the sensor element 9 (pump cell 14) (a state in which gas detection is possible).

  The sensor element 9 includes therein a measurement chamber (not shown) in which one of the pair of porous electrodes 16 in the pump cell 14 is exposed, and a reference oxygen chamber (not shown) in which the other is exposed. ing. A measurement object gas (exhaust gas in the present embodiment) is introduced into the measurement chamber from the outside through a porous diffusion layer (not shown). Atmosphere as a reference gas is introduced into the reference oxygen chamber from the outside.

  The sensor element 9 is an oxygen sensor element that detects an oxygen concentration by a so-called limit current method. The output characteristic indicating the relationship between the applied voltage Vp and the pump current Ip in the pump cell 14 includes a flat region parallel to the voltage axis, that is, a limit current region (limit current region) where the pump current Ip is constant. It is known. This flat region (limit current region) is a region where the pump current Ip does not substantially change even when the applied voltage Vp changes and maintains a constant value (limit current).

  This flat region is a limit current region indicating the pump current Ip corresponding to the oxygen concentration (that is, the air-fuel ratio), and the change in the limit current corresponds to the change in the oxygen concentration. It is known that the pump current Ip in this limit current region increases as the oxygen concentration increases. For this reason, the oxygen concentration in the exhaust gas can be detected by applying the applied voltage Vp corresponding to the limit current region to the pump cell 14 of the sensor element 9 and using the pump current Ip obtained thereby. That is, as the oxygen concentration in the exhaust gas increases (the air-fuel ratio becomes leaner), the limit current of the pump current Ip increases, and as the oxygen concentration in the exhaust gas decreases (the air-fuel ratio becomes richer), the limit Since the current decreases, the oxygen concentration (air-fuel ratio) can be detected based on the limit current.

  In the present embodiment, an applied voltage Vp is applied to the pair of porous electrodes 16 in the pump cell 14 of the sensor element 9, a pump current Ip is caused to flow between the pair of porous electrodes 16, and oxygen is pumped by the pump current Ip. (For example, oxygen is moved between the measurement chamber and the reference oxygen chamber). As is well known, the oxygen concentration can be detected based on the current value (limit current) at which the pump current Ip during pumping becomes constant.

  That is, the gas sensor 8 is used for detecting the oxygen concentration contained in the measurement target gas (exhaust gas) based on the current value (limit current) at which the pump current Ip at the time of pumping in the sensor element 9 becomes constant. Used.

[1-2. Sensor control device]
The sensor control device 5 is configured to drive and control the gas sensor 8 to detect the oxygen concentration in the exhaust gas, and to notify the engine control device 7 of the detected oxygen concentration.

The sensor control device 5 is configured by an ASIC (Application Specific IC). In FIG. 1, the sensor control device 5 is represented as a functional block diagram.
The sensor control device 5 includes an AD conversion unit 31 (analog / digital conversion unit 31), a PID calculation unit 33, a pump current calculation unit 34, a current DA conversion unit 35 (current digital / analog conversion unit 35), a gas detection signal calculation unit 37, A current supply unit 42 and a reference potential generation unit 46 are provided. The sensor control device 5 includes an Rpvs calculation unit 51, a heater control amount calculation unit 53, and a heater driver 57. Further, the sensor control device 5 includes a pump current terminal 61 (Ip + terminal 61), a detection voltage terminal 63 (Vs + terminal 63), a reference potential terminal 65 (COM terminal 65), a terminal monitoring unit 67, an abnormality detection unit 69, and communication processing. Part 71.

  The current supply unit 42 is configured to supply various currents to the sensor element 9 (specifically, the pump cell 14) via the detection voltage terminal 63. The various currents include, for example, a pulse current Irpvs for detecting the internal resistance value of the sensor element 9 (pump cell 14), and oxygen for pumping oxygen by the sensor element 9 (pump cell 14) to generate an oxygen reference electrode. A minute current Icp is exemplified. The current supply unit 42 is configured not to always supply these currents but to supply each current at an appropriate time.

  The reference potential generator 46 sets the potential of the reference potential terminal 65 (COM terminal 65) to a predetermined potential. Specifically, a potential obtained by adding a reference set voltage (2.7 V in the present embodiment) with respect to the ground potential GND of the internal combustion engine is set as the potential of the reference potential terminal 65. In the present embodiment, the potential of the reference potential terminal 65 corresponds to the reference potential for controlling the sensor element 9 (pump cell 14).

  The AD converter 31 detects the voltage across the pump cell 14 (detection voltage Vs) based on the potential of the detection voltage terminal 63 and the potential of the reference potential terminal 65, and converts the analog value indicating the detection voltage Vs into a digital value. The AD conversion unit 31 notifies the converted digital value to each unit (for example, the PID calculation unit 33 and the Rpvs calculation unit 51) of the sensor control device 5.

  Note that the voltage across the pump cell 14 (detection voltage Vs) changes according to the oxygen concentration in the measurement chamber when the minute current Icp is input by the current supply unit 42 or when the pump current Ip is input by the current DA conversion unit 35. It can be used as the output signal Vs1. Further, the voltage across both ends of the pump cell 14 (detection voltage Vs) can be used as a response signal Vs2 that changes according to the internal resistance value of the pump cell 14 when the pulse current Irpvs is input by the current supply unit 42.

  The PID calculation unit 33 is configured to execute pump current control processing by digital processing. The pump current control process is a control for controlling the pump current Ip to be supplied to the pump cell 14 so that the detection voltage Vs (sensor output signal Vs1) of the pump cell 14 becomes the target control voltage (for example, 450 mV in this embodiment). It is processing. The PID calculation unit 33 that executes the pump current control process performs PID calculation based on the deviation ΔVs between the target control voltage (450 mV) and the detected voltage Vs (sensor output signal Vs1) of the pump cell 14 so that the deviation ΔVs approaches zero. In other words (in other words, so that the detected voltage Vs approaches the target control voltage), an energization control value (energization control current Tip) of the pump current Ip for energizing the pump cell 14 is calculated.

  The pump current calculation unit 34 attenuates a frequency component higher than a predetermined first cutoff frequency (100 Hz in the present embodiment) from the digital signal representing the energization control current Tip calculated by the PID calculation unit 33. The DAC control signal S1 (first filter signal S1) is extracted by digital calculation.

  Since the DAC control signal S1 is a signal in which a frequency component (noise component) higher than the first cutoff frequency is attenuated from the digital signal indicating the energization control current Tip of the pump current Ip, the energization control current Tip of the pump current Ip is The noise signal superimposed by the digital calculation in the PID calculation unit 33 is attenuated. For this reason, even when the sampling period of the pump current Ip (digital signal) is increased, an increase in the differential noise component in the pump current Ip can be suppressed.

  The gas detection signal calculation unit 37 attenuates a frequency component higher than a predetermined second cutoff frequency (50 Hz in the present embodiment) from the digital signal representing the DAC control signal S1 extracted by the pump current calculation unit 34. The gas detection signal S2 (second filter signal S2) is extracted by digital calculation.

  Since the gas detection signal S2 is a signal in which a frequency component (noise component) higher than the second cutoff frequency is attenuated from the DAC control signal S1, a noise component (digital at the pump current calculation unit 34) is further increased from the DAC control signal S1. This is a digital signal in which a noise component superimposed by calculation is attenuated.

  The DAC control signal S1 is a digital signal indicating the energization control current Tip of the pump current Ip since the number of times of filter processing is smaller than that of the gas detection signal S2, and the most recent change in the detection voltage Vs of the pump cell 14 It becomes a digital signal in which the state is relatively greatly reflected. Since such a digital signal is a signal suitable for the feedback control of the pump cell 14, the pump current Ip generated based on the DAC control signal S <b> 1 is energized to the pump cell 14, so that the detected voltage Vs of the pump cell 14 is Oxygen pumping (pumping and pumping) by the pump cell 14 can be appropriately executed according to the latest change state. The DAC control signal S1 is a digital signal including information on the current value of the energization control value of the pump current Ip and the energization direction (forward direction, reverse direction).

  The current DA conversion unit 35 receives the DAC control signal S1 (digital value) calculated by the pump current calculation unit 34, performs DA conversion on the received DAC control signal S1, and generates a pump current as an analog value after DA conversion. Ip is energized to the pump cell 14.

  Next, the gas detection signal S2 is a digital signal indicating the energization control current Tip of the pump current Ip because the number of times of the filtering process is larger than that of the DAC control signal S1, and is a long period of time at the detection voltage Vs of the pump cell 14. The digital signal is a relatively large reflection of the change state. Such a digital signal is a signal suitable for detecting a specific component (oxygen) contained in the measurement target gas (exhaust gas). Therefore, by using the gas detection signal S2 as a signal for detecting the oxygen concentration contained in the exhaust gas, the oxygen concentration contained in the exhaust gas is determined based on the long-term change state in the detection voltage Vs of the pump cell 14. It becomes possible to detect. Thereby, the detection precision of oxygen concentration can be improved.

  The communication processing unit 71 executes communication control processing for transmitting and receiving various types of information to and from the engine control device 7 through SPI communication (serial peripheral interface communication) via the SPI communication line 72. The communication processing unit 71 transmits and receives information including at least control information related to sensor control. For example, the communication processing unit 71 transmits the gas detection signal S <b> 2 to the engine control device 7.

  The communication processing unit 71 has a function of determining whether or not the communication state with the engine control device 7 is an abnormal state (communication abnormality). When the communication processing unit 71 determines that the communication state is normal, the communication processing unit 71 resets the communication abnormality flag Fcf (Fcf = 0). When the communication processing unit 71 determines that the communication state is abnormal, the communication processing unit 71 sets the communication abnormality flag Fcf (Fcf = 1). The communication abnormality flag Fcf is one of internal flags used for various control processes in the sensor control device 5. The communication processing unit 71 transmits information to the engine control device 7 after confirming that the communication abnormality flag Fcf is in the reset state.

  The engine control device 7 calculates the concentration of the specific gas (oxygen in this embodiment) in the exhaust gas based on the gas detection signal S2. That is, the engine control device 7 determines the measurement target based on the history data of the pump current Ip that has flowed through the pump cell 14 so that the oxygen concentration in the measurement chamber becomes a predetermined target concentration (for example, the oxygen concentration corresponding to the theoretical air-fuel ratio). The oxygen concentration contained in the gas is calculated.

  The sensor control device 5 includes an EEPROM and a RAM (not shown). The EEPROM is a storage unit that stores the contents of the control process and various parameters used for the control process. Further, the EEPROM stores various information (such as an allowable maximum current of the pump cell 14) determined according to the type and characteristics of the gas sensor 8 to be controlled. These pieces of information are stored in the EEPROM at the manufacturing stage of the sensor control device 5. The RAM is a storage unit that temporarily stores control data and the like used for various control processes.

The Rpvs calculator 51 calculates the internal resistance value Rpvs of the pump cell 14 based on the response signal Vs2 and the sensor output signal Vs1 notified from the AD converter 31.
The heater control amount calculation unit 53 calculates the temperature of the gas sensor 8 (specifically, the pump cell 14 of the sensor element 9) based on the internal resistance value Rpvs calculated by the Rpvs calculation unit 51 by digital calculation. The heater heat generation amount necessary to bring the temperature close to or maintain the sensor target temperature is calculated. The heater control amount calculation unit 53 calculates a DUTY ratio of power to be supplied to the heater 26 based on the calculated heater heating value, and generates a PWM control signal corresponding to the DUTY ratio.

  Note that a predetermined value for the sensor target temperature is stored in a storage unit (ROM, RAM, etc.). The heater control amount calculation unit 53 generates a PWM control signal using the sensor target temperature read from the storage unit.

  The heater driver 57 performs energization control to the heater 26 based on the PWM control signal from the heater control amount calculation unit 53 using the power supplied from the power supply device 59. Thereby, the heat generation amount of the heater 26 becomes a heat generation amount necessary for bringing the temperature of the gas sensor 8 close to or maintaining the sensor target temperature.

  The pump current terminal 61 and the detection voltage terminal 63 are connected to one of the pair of porous electrodes 16 in the pump cell 14 of the sensor element 9, and the reference potential terminal 65 is connected to the other of the pair of porous electrodes 16. Has been. The pump current terminal 61 is electrically connected to the porous electrode 16 by being connected to the connection path between the detection voltage terminal 63 and the sensor element 9 (porous electrode 16) inside the gas detection device 3. Yes.

  The terminal monitoring unit 67 detects each potential (analog value) of the pump current terminal 61, the detection voltage terminal 63, and the reference potential terminal 65, AD converts each detected potential, and converts each potential (digital value) after conversion. ) Is transmitted to the abnormality detection unit 69.

  The abnormality detection unit 69 determines whether or not the potentials of the pump current terminal 61, the detection voltage terminal 63, and the reference potential terminal 65 are included in a predetermined normal range, and a terminal whose potential deviates from the normal range. It is determined that the state is abnormal. For example, when a wiring abnormality state (ground short circuit abnormality state) in which the terminal is erroneously electrically connected to the ground potential GND or a wiring abnormality state (battery short circuit abnormality state) in which the terminal is erroneously connected to the power supply device 59 occurs. The potential at the terminal deviates from the normal range.

  That is, the abnormality detection unit 69 is based on the potential of each terminal (pump current terminal 61, detection voltage terminal 63, reference potential terminal 65), and each of the current DA conversion unit 35, current supply unit 42, and reference potential generation unit 46. Is configured to detect a control abnormality including at least a wiring abnormality in a wiring connecting the sensor element 9 and the sensor element 9. If the abnormality detection unit 69 determines that at least one of the terminals is in an abnormal state, the abnormality detection unit 69 calculates an abnormality information signal including information on the terminal determined to be in the abnormal state as a PID calculation unit 33 or a heater control amount calculation. It transmits to the part 53 etc.

  When the PID calculation unit 33 and the heater control amount calculation unit 53 receive the abnormality information signal, the PID calculation unit 33 and the heater control amount calculation unit 53 execute an abnormality handling process according to the abnormality information signal. For example, the PID calculation unit 33 executes a process for stopping energization of the pump cell 14 as the abnormality handling process. Further, the heater control amount calculation unit 53 executes a process for reducing the power supplied to the heater 26 (in other words, the DUTY ratio of the voltage applied to the heater) as the abnormality handling process.

  If there is a terminal determined to be in an abnormal state, the abnormality detection unit 69 sends an abnormality information signal including information on the terminal determined to be in an abnormal state to the engine control device 7 via the communication processing unit 71. Send. The engine control device 7 executes the concentration detection process so that the gas detection signal S2 output from the sensor control device 5 during reception of the abnormality information signal is not a normal value but an abnormal value and is not used for oxygen concentration detection. To do. Accordingly, the engine control device 7 can suppress a decrease in detection accuracy when detecting the oxygen concentration based on the gas detection signal S2 from the sensor control device 5.

[1-3. Heater control switching process]
The heater control switching process executed by the heater control amount calculation unit 53 will be described with reference to the flowchart of FIG. The heater control switching process is executed every predetermined execution cycle (for example, every 10 msec).

  When the heater control switching process is started, first, in S110 (S represents a step), the heater control amount calculation unit 53 determines whether or not the abnormal-time control voltage Vem has been set, and if an affirmative determination is made. The process proceeds to S130, and if a negative determination is made, the process proceeds to S120. The abnormality control voltage Vem corresponds to the effective voltage value of the voltage applied to the heater 26 in the abnormality handling process executed when the abnormality information signal is received from the abnormality detection unit 69.

  When a negative determination is made in S110 and the process proceeds to S120, the heater control amount calculation unit 53 executes a process of receiving the abnormal control voltage Vem from the engine control device 7 via the communication processing unit 71 and the received abnormal control. By storing the voltage Vem in a storage unit (RAM or the like), processing for setting the control voltage Vem at the time of abnormality is executed.

  The engine control device 7 executes processing for calculating an appropriate value as the control voltage Vem at the time of abnormality in accordance with various conditions such as the operating state of the internal combustion engine. The abnormal control voltage Vem is a voltage set within a voltage range that does not cause the heater 26 to be damaged. For example, the control voltage Vem is 50% or 30% of the maximum value (allowable maximum voltage value) of the voltage that can be applied to the heater 26. The value may be a 10% value, or may be 0 [V].

  When an affirmative determination is made in S110 and the process proceeds to S130, the heater control amount calculation unit 53 determines whether or not a sensor abnormality has occurred. If an affirmative determination is made, the process proceeds to S140, and if a negative determination is made, the process proceeds to S150. Here, “sensor abnormality” is a concept including an abnormal state of the gas sensor 8 and an abnormal state of the sensor control device 5, and means a state in which state quantity detection using the gas sensor 8 cannot be performed normally. Examples of the sensor abnormality include a wiring abnormality state determined by the abnormality detection unit 69. When the heater control amount calculation unit 53 receives an abnormality information signal indicating a wiring abnormality state from the abnormality detection unit 69, the heater control amount calculation unit 53 determines that the sensor is abnormal (wiring abnormality state).

  When an affirmative determination is made in S130 and the process proceeds to S140, the heater control amount calculation unit 53 executes heater control in an abnormal time control mode as an abnormality handling process. Specifically, the PWM control signal is generated so that the applied voltage (effective value) to the heater 26 becomes the abnormal control voltage Vem. That is, in the abnormal time control mode, feedback control using the internal resistance value Rpvs calculated by the Rpvs calculating unit 51 is not performed, but a PWM control signal is generated based on a predetermined abnormal time control voltage Vem.

  When a negative determination is made in S130 and the process proceeds to S150, the heater control amount calculation unit 53 determines whether or not the communication state with the engine control device 7 is an abnormal state (communication abnormality), and if an affirmative determination is made, the process proceeds to S180. If a negative determination is made, the process proceeds to S160. At this time, the heater control amount calculation unit 53 determines whether there is a communication abnormality based on the state (set state, reset state) of the communication abnormality flag Fcf.

  When a negative determination is made in S150 and the process proceeds to S160, the heater control amount calculation unit 53 receives command information related to heater control from the engine control device 7 via the communication processing unit 71. For this command information, heater control is performed using the sensor target temperature (hereinafter also referred to as a specified temperature) stored in the storage unit of the sensor control device 5 as it is, or a corrected target temperature obtained by correcting the specified temperature is used. Instruction contents indicating whether to perform heater control. The command content of the command information is determined and set by the engine control device 7 according to various conditions such as the operating state of the internal combustion engine. By using such command information, for example, when the operating state of the internal combustion engine is a normal state, heater control is performed using the specified temperature as it is, and when the operating state of the internal combustion engine is a special state, The sensor target temperature can be set to a temperature different from the specified temperature.

In step S170, the heater control amount calculation unit 53 performs heater control based on the command information received in step S160.
When an affirmative determination is made in S150 and the process proceeds to S180, the heater control amount calculation unit 53 performs heater control based on the last command information received before the communication abnormality occurs. That is, when a communication abnormality occurs, a new command signal cannot be received from the engine control device 7, and therefore heater control is performed based on the last received command signal.

When S170 or S180 ends, the heater control switching process ends.
The heater control amount calculation unit 53 that executes such heater control switching processing receives the latest command signal from the engine control device 7 and performs heater control depending on whether or not a communication abnormality with the engine control device 7 has occurred. Whether to execute the heater control based on the last received command signal without receiving the latest command signal from the engine control device 7 is switched.

[1-4. effect]
As described above, in the sensor control device 5 in the gas detection system 1 of the present embodiment, the communication processing unit 71 has a function of transmitting and receiving various types of information to and from the engine control device 7, and the engine control device. 7 has a function of determining whether or not the communication state with the terminal 7 is an abnormal state (communication abnormality). When the communication processing unit 71 determines that the communication state is normal, the communication processing unit 71 resets the communication abnormality flag Fcf (Fcf = 0). When the communication processing unit 71 determines that the communication state is abnormal, the communication processing unit 71 sets the communication abnormality flag Fcf (Fcf = 1).

  The heater control amount calculation unit 53 determines whether or not a communication abnormality has occurred based on whether or not the communication abnormality flag Fcf is set (S150). If there is a communication abnormality (Yes in S150). (Determination), heater control is performed based on the last command information received before the communication abnormality (S180). That is, when a communication abnormality occurs, a new command signal cannot be received from the engine control device 7, and the heater control amount calculation unit 53 performs communication by performing heater control based on the last received command signal. The heater 26 is controlled while maintaining the heater control state when an abnormality has occurred.

  Thus, when the communication processing unit 71 detects a communication abnormality, the sensor control device 5 does not immediately shift the heater control state to another control state (for example, the heater energization is stopped), but the communication abnormality. The heater 26 is controlled while maintaining the heater control state before detection. For this reason, the sensor control device 5 can maintain the activated state of the gas sensor 8 (sensor element 9) even when a communication abnormality occurs with the engine control device 7, and early after the communication abnormality is resolved. In addition, the detection using the gas sensor 8 can be resumed.

  Therefore, the sensor control device 5 can quickly restart the state quantity detection using the gas sensor 8 when a communication abnormality occurs in communication with the engine control device 7 and the communication abnormality is subsequently eliminated.

  Next, the sensor control device 5 includes an abnormality detection unit 69 for detecting a control abnormality. The abnormality detection unit 69 is configured to detect the current DA conversion unit 35, the current supply unit 42, the reference potential generation unit 46, and the sensor based on the potential of each terminal (pump current terminal 61, detection voltage terminal 63, reference potential terminal 65). A control abnormality including at least a wiring abnormality in a wiring connecting the element 9 is detected. If the abnormality detection unit 69 determines that at least one of the terminals is in an abnormal state, the abnormality detection unit 69 calculates an abnormality information signal including information on the terminal determined to be in the abnormal state as a PID calculation unit 33 or a heater control amount calculation. It transmits to the part 53 etc.

  When the abnormality detection unit 69 detects a control abnormality (positive determination in S130), the heater control amount calculation unit 53 determines whether the communication processing unit 71 has detected a communication abnormality (in other words, the communication abnormality flag Fcf is set). Regardless of whether or not), the control state of the heater 26 is shifted to the abnormal state control state mode (S140).

  The heater control amount calculation unit 53 detects an abnormality both in the normal heater control state (S170) and not in the communication abnormality (S170) and when the heater control state is continued before the communication abnormality is detected (S180). When the unit 69 detects a control abnormality, the control state of the heater 26 is shifted to the abnormal time control mode (S140). By shifting the control state of the heater 26 to the abnormal time control mode in this way, it is possible to suppress the normal control of the heater 26 from being continued in a state where the control abnormality has occurred. Thereby, the sensor control device 5 can suppress the occurrence of breakage of the heater 26 due to the normal control of the heater 26 being continued.

  The wiring abnormality includes, for example, a short circuit abnormality (ground short circuit, power supply short circuit, etc.), a disconnection abnormality, and the like. Further, the stop of the control of the heater 26 means, for example, a stop of energization of the heater 26.

  Next, in the abnormal control mode (S140), the heater control amount calculation unit 53 sets the applied voltage (effective value) to the heater 26 to the abnormal control voltage Vem received from the engine control device 7. That is, in the abnormal control mode, the heater control amount calculation unit 53 does not perform feedback control using the internal resistance value Rpvs calculated by the Rpvs calculation unit 51, but based on a predetermined abnormal control voltage Vem. To generate a PWM control signal.

  The sensor control device 5 can suppress the feedback control from diverging and the application voltage to the heater 26 from becoming inappropriate by setting the application voltage to the heater 26 to the abnormal time control voltage Vem as described above. Damage to the heater 26 due to improper voltage application can be suppressed.

Next, the heater control amount calculation unit 53 is configured to receive command information related to heater control from the engine control device 7 via the communication processing unit 71 (S160).
The sensor control device 5 including the heater control amount calculation unit 53 performs normal heater control based on the received command information in a situation where the heater control command information can be received (No in S150). Thus, heater control according to the command of the engine control device 7 can be realized (S170), but when communication abnormality occurs, the heater control command information cannot be received from the engine control device 7.

  For this reason, when a communication abnormality occurs (Yes in S150), the sensor control device 5 continues the heater control based on the last normally received heater control command information (S180). Compared with the case where the heater energization is stopped when it occurs, the time required for returning to the normal control after the communication abnormality is resolved can be shortened.

[1-5. Correspondence of wording]
Here, the correspondence between words will be described.
The sensor control device 5 corresponds to an example of a sensor control device, the gas sensor 8 corresponds to an example of a sensor, the sensor element 9 corresponds to an example of an element portion, the pump cell 14 corresponds to an example of a cell, and a pair of porous The electrode 16 corresponds to an example of a pair of electrodes, the heater 26 corresponds to an example of a heater unit, and the engine control device 7 corresponds to an example of an external device.

  The current DA conversion unit 35 and the current supply unit 42 correspond to an example of a sensor drive unit, the heater control amount calculation unit 53 corresponds to an example of a heater control unit, and the communication processing unit 71 includes an information communication unit and a communication abnormality detection unit. It corresponds to an example, the abnormality detection unit 69 corresponds to an example of a control abnormality detection unit, the abnormal time control mode corresponds to an example of an abnormal time control state, and the abnormal time control voltage Vem corresponds to an example of an abnormal time applied voltage. .

[2. Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is possible to implement in various aspects.

  For example, in the above-described embodiment, the sensor control device that controls the element unit (sensor element 9) including only one cell (pump cell 14) has been described. However, the element unit to be controlled is limited to such a configuration. There may be no element part provided with two or more cells. For example, the sensor control apparatus which controls an element part (2 cell type element part) provided with a pump cell and an electromotive force cell (detection cell) may be sufficient. In the case of controlling a sensor including a two-cell type element unit and a heater unit using the sensor control device 5 described above, a pump cell is connected between a pump current terminal 61 and a reference potential terminal 65, and a detection voltage terminal 63. And a reference potential terminal 65 are connected to an electromotive force cell (detection cell). Even in such an application, the sensor control device 5 uses a sensor having a two-cell type element portion promptly when a communication abnormality occurs in communication with the engine control device 7 and the communication abnormality is resolved thereafter. The state quantity detection that has been made can be resumed.

  Next, in the above-described embodiment, the sensor control device 5 configured to receive the abnormal-time control voltage Vem from the engine control device 7 has been described, but the configuration is not limited thereto. For example, the configuration may be such that the abnormal control voltage Vem is stored in advance in a storage unit (ROM or the like) of the sensor control device 5 and does not receive the abnormal control voltage Vem from the engine control device 7.

  Next, in the above embodiment, an embodiment using an oxygen sensor as a sensor has been described. However, a gas sensor that detects a gas other than oxygen (for example, NOx) may be used. The sensor is not limited to a gas sensor, and may be a sensor other than a gas sensor as long as the sensor includes an element unit and a heater.

  Next, the function of one component in each of the above embodiments may be shared by a plurality of components, or the function of a plurality of components may be exhibited by one component. Moreover, you may abbreviate | omit a part of structure of each said embodiment. In addition, at least a part of the configuration of each of the above embodiments may be added to or replaced with the configuration of the other above embodiments. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure. For example, in the above embodiment, the communication processing unit 71 has been described as an example corresponding to an information communication unit and a communication abnormality detection unit. However, the communication processing unit 71 corresponds to an example of an information communication unit, and the communication processing unit 71 The form with which another abnormality detection part is equipped as what corresponds to an example of a communication abnormality detection part may be sufficient.

  In addition, the sensor control device is not limited to the form configured by the ASIC as described above, and may be a form including a microcomputer (hereinafter also referred to as a microcomputer), for example. The microcomputer includes a CPU, a ROM, a RAM, and a signal input / output unit. Various functions of such a sensor control device are realized by the CPU executing a program stored in a non-transitional physical recording medium. In this example, the ROM corresponds to a non-transitional tangible recording medium that stores a program. Further, by executing this program, a method corresponding to the program is executed. The signal input / output unit transmits / receives various signals to / from an external device. Note that the number of CPUs, ROMs, RAMs, and signal input / output units constituting the microcomputer may be one or more. Further, some or all of the functions executed by the microcomputer may be configured in hardware by one or a plurality of ICs.

  In addition to the ASIC and the microcomputer described above, the present disclosure includes a system including the microcomputer as a constituent element, a program for causing the computer to function as the microcomputer, a non-transitory actual recording medium such as a semiconductor memory storing the program, a concentration The present disclosure can also be realized in various forms such as a calculation method.

  DESCRIPTION OF SYMBOLS 1 ... Gas detection system, 3 ... Gas detection apparatus, 5 ... Sensor control apparatus, 7 ... Engine control apparatus, 8 ... Gas sensor, 9 ... Sensor element, 14 ... Pump cell, 15 ... Solid electrolyte body, 16 ... Porous electrode, 26 ... Heater, 31 ... Analog / digital converter (AD converter), 33 ... PID calculator, 34 ... Pump current calculator, 35 ... Current digital / analog converter (current DA converter), 37 ... Gas detection signal calculator, 42 ... current supply unit, 46 ... reference potential generation unit, 51 ... Rpvs calculation unit, 53 ... heater control amount calculation unit, 57 ... heater driver, 61 ... pump current terminal (Ip + terminal), 63 ... detection voltage terminal (Vs + terminal) ), 65... Reference potential terminal (COM terminal), 67... Terminal monitoring unit, 69 .. abnormality detection unit, 71 .. communication processing unit, 72.

Claims (3)

A sensor control device that controls a sensor having a solid electrolyte body and an element section having at least one cell including a pair of electrodes provided on the solid electrolyte body and a heater section that heats the solid electrolyte body. And
A sensor driving unit connected to the element unit and energizing the cell to drive the element unit;
A heater control unit that controls the heater unit in one energization mode instructed by an external device among a plurality of energization modes;
An information communication unit that transmits and receives information including at least control information related to control of the sensor to and from the external device;
With
Furthermore, a communication abnormality detection unit that detects a communication abnormality with the external device,
When the communication abnormality is detected by the communication abnormality detection unit, the heater control unit controls the heater unit while maintaining the heater control state in the energization mode before the communication abnormality is detected. ,
Sensor control device. A control abnormality detecting unit for detecting a control abnormality including at least a wiring abnormality in a wiring connecting the sensor driving unit and the element unit;
When the control abnormality detection unit detects the control abnormality, the heater control unit changes the control state of the heater unit to the abnormal state control state regardless of whether the communication abnormality detection unit detects the communication abnormality. Transition,
The sensor control device according to claim 1. The heater control unit sets the applied voltage to the heater unit to a predetermined abnormal applied voltage set in advance in the abnormal control state.
The sensor control device according to claim 2.

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