JP2019002842A - Control state setting device and sensor control system - Google Patents

Abstract

To provide a control state setting device capable of setting state detection timing of a sensor element to a period when the control state of a heater part is taken into consideration even when controlling the heater part using an individual heater control part different from a sensor control part in controlling the sensor having the sensor element and heater part.SOLUTION: A control state setting device sets, when setting a control state of a sensor by a sensor control part, a heater control mode command and an element state detection mode command by a mode setting part based upon a pulse electrification signal to a heater part by an individual heater control part. Consequently, an element state detection part of the sensor control part can sets a state detection period of the sensor element according to an actual heater control state. This control state setting device can properly set the state detection period of the sensor element by the element state detection part even when configured to control the heater part of the sensor under heater control not by an internal heater control part of the sensor control part, but by a separately provided individual heater control part.SELECTED DRAWING: Figure 5

Description

  The present disclosure relates to a control state setting device and a sensor control system.

  A sensor control unit that controls a sensor including a sensor element and a heater unit is known. A control state setting device for setting the control state of a sensor by such a sensor control unit is known. Also, a sensor control system including a sensor control unit and a control state setting device is known (Patent Document 1).

  Some sensor control units include an element state detection unit that detects the state of the sensor element and a heater control unit that controls the heater unit. The sensor control unit having such a configuration detects the state of the sensor element based on the heater control mode command and the element state detection mode command from the outside, and controls the heat generation state of the heater unit based on the detection result. It is configured as follows.

  The control state setting device is configured to set the control state of the sensor by the sensor control unit by transmitting a heater control mode command and an element state detection mode command to the sensor control unit.

JP 2013-210361 A

  However, depending on the application of the sensor, the sensor element and the heater unit are not controlled only by the sensor control unit, and the sensor element is controlled using the sensor control unit, and the individual heater control provided separately from the sensor control unit A configuration may be employed in which the heater unit is controlled using the unit.

  In such a configuration, since the individual heater control unit controls the heater unit, the sensor control unit cannot determine the actual control state of the heater unit, and the sensor unit state detection timing is determined by the control state of the heater unit. It becomes difficult to set the time when it is considered.

  Therefore, in the present disclosure, in the control of the sensor including the sensor element and the heater unit, even when the heater unit is controlled using an individual heater control unit different from the sensor control unit, the state detection timing of the sensor element is set in the heater unit. It is an object of the present invention to provide a control state determination device that can be set at a time when the control state is considered, and to provide a sensor control system including such a control state determination device.

One aspect of the present disclosure is a control state setting device that sets a control state of a sensor by a sensor control unit, and is a control state setting device that includes a mode setting unit.
The sensor control unit is configured to control a sensor including a sensor element and a heater unit. The sensor control unit includes an element state detection unit and a built-in heater control unit.

  The element state detection unit detects the state of the sensor element when both the heater control mode command and the element state detection mode command are mode ON commands based on the heater control mode command and the element state detection mode command from the outside. Is configured to do. The built-in heater control unit is configured to control the heater unit when the heater control mode command is a mode ON command based on the heater control mode command.

The heater unit is configured not to be a built-in heater control unit, but to be energized and controlled by a pulse energization signal output from an individual heater control unit provided separately from the sensor control unit.
The mode setting unit is configured to set a heater control mode command and an element state detection mode command output to the sensor control unit based on a pulse energization signal to the heater unit by the individual heater control unit. When the mode setting unit receives detection trigger information representing a specific energization state determined in advance among the pulse energization signals output from the individual heater control unit, a heater control mode command output to the sensor control unit and Each element state detection mode command is set to the ON state.

  In this control state setting device, since the mode setting unit sets the heater control mode command and the element state detection mode command based on the pulse energization signal to the heater unit by the individual heater control unit, the element state detection unit of the sensor control unit The sensor element state detection timing can be set according to the actual heater control state.

  According to such a control state setting device, the heater unit of the sensor is controlled not by the heater control by the built-in heater control unit of the sensor control unit but by the heater control by the separately provided individual heater control unit. The state detection timing of the sensor element by the element state detection unit can be set appropriately. For this reason, by using this control state setting device, even if the individual heater control unit performs the heater control, the state of the sensor element can be detected as it is without modifying the sensor control unit including the built-in heater control unit. It becomes possible.

  Therefore, according to this control state setting device, in the control of the sensor including the sensor element and the heater unit, even when the heater unit is controlled using an individual heater control unit different from the sensor control unit, the state detection of the sensor element is performed. The timing can be set to a time when the control state of the heater unit by the individual heater control unit (the energization control state by the pulse energization signal) is considered. That is, according to this control state setting device, even when the heater unit is controlled using an individual heater control unit different from the sensor control unit, the sensor is controlled using the sensor control unit including the built-in heater control unit. Is possible.

Next, in the control state setting device described above, the detection trigger information may be an OFF edge signal indicating a switching time from ON to OFF in the pulse energization signal.
Thus, by using the OFF edge signal as detection trigger information, the mode setting unit can determine when the pulse energization signal output from the individual heater control unit to the heater unit is in the OFF state. Therefore, the mode setting unit can set the heater control mode command and the element state detection mode command to the mode ON command based on the time when the detection trigger information is in the OFF state, and the sensor state detection by the element state detection unit. Timing can be set.

Thereby, the element state detection part can perform the state detection of a sensor element at the appropriate timing set based on the actual heater control state.
Examples of the sensor element state detection include measurement of impedance of the sensor element.

  Next, in the above control state setting device, the sensor control unit is configured to receive from the outside a power command value that is a command value of the amount of power supplied to the heater unit by the built-in heater control unit. The setting device may include a power command value output unit that outputs, as a power command value, a minimum value in a range of power supply that can be supplied to the heater unit by the built-in heater control unit to the sensor control unit.

  By providing such a power command value output unit, the control state setting device provides energization time to the heater unit when PWM control is performed on the heater unit in virtual control by the built-in heater control unit of the sensor control unit. Can be set to the shortest. As a result, it is possible to set the time until the energization to the heater unit is stopped after the virtual heater control by the built-in heater control unit is started, so that the sensor element by the element state detection unit when the heater energization is stopped The state detection timing can be set to an early time.

  As a result, the control state setting device sets the minimum time required to detect the state of the sensor element by the sensor control unit (specifically, the element state detection unit) after receiving the detection trigger information from the individual heater control unit. be able to.

  Next, in the control state setting device, the element state detection unit detects the state of the sensor element when both the heater control mode command and the element state detection mode command are changed from the mode OFF command to the mode ON command. Then, during the period in which both the heater control mode command and the element state detection mode command are mode ON commands, the state of the sensor element may be detected at a predetermined detection cycle.

  The control state setting device does not employ a configuration in which an individual signal indicating the state detection timing of the sensor element is output to the sensor control unit, and the switching timing between the heater control mode command and the element state detection mode command (from the mode OFF command to the mode ON command). The timing for detecting the state of the sensor element can be transmitted to the sensor control unit.

This eliminates the need for modification of the sensor control unit, so that the control state setting device can set the state detection timing of the sensor element while using the existing sensor control unit.
Note that “the heater control mode command and the element state detection mode command are both changed from the mode OFF command to the mode ON command” is not limited to the case where the two commands are changed at the same time. However, it is a concept including the case where both of the two commands are changed to the mode ON command.

Another aspect of the present disclosure is a sensor control system including a sensor control unit and a control state setting device, and the control state setting device is the control state setting device described above.
The sensor control unit is configured to control a sensor including a sensor element and a heater unit. The sensor control unit includes an element state detection unit and a built-in heater control unit. The element state detection unit detects the state of the sensor element when both the heater control mode command and the element state detection mode command are mode ON commands based on the heater control mode command and the element state detection mode command from the outside. Is configured to do. The built-in heater control unit is configured to control the heater unit when the heater control mode command is a mode ON command based on the heater control mode command.

The heater unit is configured not to be a built-in heater control unit, but to be energized and controlled by a pulse energization signal output from an individual heater control unit provided separately from the sensor control unit.
Since this sensor control system includes the above-described control state setting device, even when the heater unit is controlled using an individual heater control unit different from the sensor control unit in the control of the sensor including the sensor element and the heater unit. The sensor can be controlled using the sensor control unit including the built-in heater control unit.

It is a schematic block diagram of a sensor control system provided with a central processing unit and a sensor control apparatus. It is a schematic block diagram of a gas sensor provided with a gas sensor element and a heater. It is a flowchart showing the processing content of a mode setting process. It is a flowchart showing the processing content of a Rpvs measurement determination process. It is a timing chart showing the state of each part in a sensor control system. It is a flowchart showing the processing content of a mode setting process. It is a flowchart showing the processing content of a virtual heater control process. It is a flowchart showing the processing content of heater energization control processing. It is a flowchart showing the processing content of Rpvs measurement pulse control 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]
As a first embodiment, a sensor control system 1 that controls a gas sensor 5 will be described with reference to FIG.

  The gas sensor 5 is provided in an exhaust pipe of the internal combustion engine, and includes a gas sensor element 5a and a heater 5b. The gas sensor element 5a is configured to detect a specific gas concentration (oxygen concentration) in a measurement target gas (exhaust gas or the like). The heater 5b includes a heating resistor 5c (see FIG. 2) that generates heat when energized from the outside, and is configured to heat the gas sensor element 5a.

The sensor control system 1 includes a central processing unit 2 (MCU 2), a sensor control device 3, and a heater energization control circuit 6.
The central processing unit 2 is connected to the sensor control unit 3 and the heater energization control circuit 6 and is configured to execute various control processes. The sensor control device 3 is configured to detect various characteristics (impedance, cell voltage, etc.) of the gas sensor element 5a. The heater energization control circuit 6 is configured to control energization of the heater 5b in order to adjust the amount of heat generated by the heater 5b.

  The sensor control device 3 is connected to the gas sensor element 5 a of the gas sensor 5. The sensor control device 3 detects an element impedance signal Srpvs that changes according to the impedance of the gas sensor element 5a, and outputs the detected element impedance signal Srpvs to the central processing unit 2. The sensor control device 3 has a function of outputting a gas detection signal Vip detected using the gas sensor element 5a to the central processing unit 2 in addition to the element impedance signal Srpvs. The gas detection signal Vip changes according to the gas concentration of the specific gas detected by the gas sensor element 5a.

  The heater energization control circuit 6 is connected to the heater 5b, and executes a heater control process for controlling the amount of power supplied to the heater 5b in order to set the gas sensor element 5a to a target temperature. In the heater control process, the heater energization control circuit 6 controls the energization of, for example, the duty ratio of the heater voltage Vh applied to the heater 5b (in other words, the duty ratio of the pulse signal supplied to the heater 5b). In addition to controlling the amount of power supplied to the gas sensor, control is performed to bring the gas sensor element 5a closer to the target temperature. The heater energization control circuit 6 outputs a heater voltage signal Svh representing the state of the heater voltage Vh applied to the heater 5b to the central processing unit 2.

  The central processing unit 2 is mainly composed of a microcomputer 2a (microcomputer 2a) having a CPU, RAM, ROM, I / O interface and the like. The central processing unit 2 executes various control processes using various information received from each unit.

  For example, the microcomputer 2a of the central processing unit 2 detects the temperature of the gas sensor element 5a using the element impedance signal Srpvs received from the sensor control device 3, or the gas detection signal Vip received from the sensor control device 3. Based on the above, a gas concentration detection process for detecting a specific gas concentration (oxygen concentration) in the measurement target gas (exhaust gas or the like) is executed.

  Further, the microcomputer 2a of the central processing unit 2 executes a mode setting process for setting the virtual heater control mode command Sh and the Rpvs measurement function command Sr to be output to the sensor control device 3. The microcomputer 2a of the central processing unit 2 sets the virtual heater control mode command Sh and the Rpvs measurement function command Sr based on the heater voltage signal Svh received from the heater energization control circuit 6, whereby the gas sensor by the sensor control device 3 The detection timing of the element impedance Rpvs of the element 5a is controlled.

[1-2. Gas sensor]
As shown in FIG. 2, the gas sensor 5 is configured by laminating a plate-type gas sensor element 5a and a plate-type heater 5b. A reinforcing plate 30 is provided between the gas sensor element 5a and the heater 5b.

The gas sensor element 5 a is configured by stacking a pump cell 14, a porous diffusion layer 18, and an electromotive force cell 24.
The pump cell 14 is formed of partially stabilized zirconia (ZrO ₂ ), which is an oxygen ion conductive solid electrolyte body, and has porous electrodes 12 and 16 mainly formed of platinum on the front and back surfaces thereof. The porous electrode 12 is covered with a porous protective layer 15, and the protective layer 15 is provided as a poisoning prevention layer for preventing the porous electrode 12 from being poisoned.

The electromotive force cell 24 is formed of partially stabilized zirconia (ZrO ₂ ), which is also an oxygen ion conductive solid electrolyte, and has porous electrodes 22 and 28 mainly formed of platinum on each of the front and back surfaces thereof. ing.

  The porous electrode 16 facing the hollow diffusion chamber 20 in the pump cell 14 and the porous electrode 22 facing the hollow diffusion chamber 20 in the electromotive force cell 24 are electrically connected to each other and are connected to the terminals of the gas sensor element 5a. Connected to COM. The terminal COM is connected to the Vcent point of the sensor control device 3 through the energization path 42 and the resistor R (see FIG. 1).

  The porous electrode 12 of the pump cell 14 is connected to the terminal Ip + of the gas sensor element 5a, and the porous electrode 28 of the electromotive force cell 24 is connected to the terminal Vs + of the gas sensor element 5a. The terminal Ip + is connected to the output terminal of the second operational amplifier OP2 in the sensor control device 3, and the terminal Vs + is connected to the non-inverting input terminal + of the fourth operational amplifier OP4 in the sensor control device 3 via the energization path 40. (See FIG. 1).

The reinforcing plate 30 is stacked on the electromotive force cell 24 so as to form the reference oxygen chamber 26 inside the porous electrode 28 while closing the porous electrode 28 of the electromotive force cell 24.
A diffusion chamber 20 surrounded by a porous diffusion layer 18 is formed between the pump cell 14 and the electromotive force cell 24. That is, the diffusion chamber 20 is communicated with the measurement gas atmosphere via the porous diffusion layer 18.

  The heater 5b is integrated with the gas sensor element 5a (pump cell 14 and electromotive force cell 24) via the reinforcing plate 30. The heater 5 b has a configuration in which a heating resistor 5 c made of a conductor is sandwiched between a pair of alumina sheets 83 and 85. The heater 5b (specifically, the heating resistor 5c) is connected to the heater energization control circuit 6, and heats the pump cell 14 and the electromotive force cell 24 by generating heat by energization. When the pump cell 14 and the electromotive force cell 24 are activated by the heating of the heater 5b, the gas sensor element 5a can perform gas detection (oxygen concentration detection).

[1-3. Sensor control device]
Next, the oxygen concentration measurement operation using the gas sensor element 5a by the sensor control device 3 will be described.

  As shown in FIG. 1, the sensor control device 3 causes a constant minute current Icp to flow from the constant current source circuit 62 to the electromotive force cell 24 so that the voltage Vs generated at both ends of the electromotive force cell 24 becomes 450 mV. The pump current Ip flowing through the pump cell 14 is controlled to pump oxygen in or out of the diffusion chamber 20. That is, the oxygen concentration in the diffusion chamber 20 is adjusted using the pump cell 14 so that the voltage Vs generated at both ends of the electromotive force cell 24 becomes 450 mV.

  Since the current value and current direction of the pump current Ip flowing through the pump cell 14 change according to the oxygen concentration (air-fuel ratio) in the exhaust gas, the oxygen concentration in the exhaust gas is calculated based on this pump current Ip. Can do. The reference oxygen chamber 26 functions as an internal oxygen reference source by flowing a minute current Icp to the electromotive force cell 24 in the direction of pumping out oxygen from the diffusion chamber 20 to the porous electrode 28 side.

  In addition to the constant current source circuit 62, the sensor control device 3 includes a first operational amplifier OP1 to a fifth operational amplifier OP5, a first switch SW1 to a third switch SW3, a PID control circuit 69, and the like. The constant current source circuit 62, the electromotive force cell 24, and the resistor R are connected in this order to form a current path through which the minute current Icp flows.

  The second operational amplifier OP2 has one input terminal connected to the Vcent point, the other input terminal applied with a reference voltage + 3.6V, and an output terminal connected to the terminal Ip + of the pump cell 14. The PID control circuit 69 PID-controls the magnitude of the pump current Ip so that the potential difference between the potential of the terminal Vs + of the electromotive force cell 24 connected via the first operational amplifier OP1 and the potential at the Vcent point is 450 mV. . Specifically, in the PID control circuit 69, the deviation between the target control voltage (450 mV) and the voltage Vs generated at both ends of the electromotive force cell 24 is PID-calculated and fed back to the second operational amplifier OP2. The two operational amplifier OP2 causes the pump current Ip to flow through the pump cell 14.

  The sensor control device 3 detects the magnitude of the pump current Ip, converts it into a voltage signal, and differentially amplifies the voltage across the detection resistor R1 (difference between the potential Vcent and the potential Vpid) to generate gas. And a differential amplifier circuit 61 that outputs a detection signal (Vip signal). This gas detection signal (Vip signal) is output from the gas detection signal output terminal 43 to the central processing unit 2.

  The central processing unit 2 (the microcomputer 2a) converts the gas detection signal (Vip signal) into a digital value by an A / D conversion circuit (not shown), and then, based on the map or calculation formula held, the gas detection signal ( An oxygen concentration calculation process for calculating an oxygen concentration value corresponding to the (Vip signal) is executed.

Next, the element impedance (element temperature) measurement operation of the electromotive force cell 24 in the sensor control device 3 will be described.
In the sensor control device 3, the first operational amplifier OP1 forms a sample and hold circuit together with the first capacitor C1 and the first switch SW1. This sample and hold circuit switches the first switch SW1 from the on state to the off state when measuring the impedance of the electromotive force cell 24, and the voltage generated at both ends of the electromotive force cell 24 immediately before the current application for measuring the element impedance of the electromotive force cell 24 By holding Vs, the voltage Vs immediately before the element impedance measurement is input to the PID control circuit 69.

  The third operational amplifier OP3 has a hold value (the voltage Vs of the electromotive force cell 24 immediately before the impedance measurement current is passed) held in the first operational amplifier OP1, and the impedance measurement current -Iconst to the electromotive force cell 24. Voltage change amount ΔVs corresponding to the difference from Vs + potential (output potential of the fourth operational amplifier OP4) at the time of energizing is output. Since this voltage change amount ΔVs is proportional to the bulk resistance value of the electromotive force cell 24, it can be used as the element impedance signal Srpvs representing the element impedance Rpvs of the electromotive force cell 24.

  That is, the third operational amplifier OP3 outputs the voltage change amount ΔVs and the element impedance signal Srpvs proportional to the bulk resistance value of the electromotive force cell 24. The element impedance signal Srpvs has a characteristic proportional to the bulk resistance value of the electromotive force cell 24.

The element impedance signal Srpvs (voltage change amount ΔVs) output from the third operational amplifier OP3 is output to the central processing unit 2 via the fifth operational amplifier OP5.
The fifth operational amplifier OP5 forms a signal hold circuit together with the second capacitor C2, the second switch SW2, and the resistor R2. In the signal hold circuit, first, when the second switch SW2 is turned from OFF to ON when measuring the impedance of the electromotive force cell 24, the voltage change amount ΔVs is input from the third operational amplifier OP3. Thereafter, when the second switch SW2 is turned off, the signal hold circuit holds the voltage change ΔVs output from the third operational amplifier OP3 by the second capacitor C2 when the second switch SW2 is turned on. At the same time, the element impedance signal Srpvs representing the voltage change amount ΔVs is output to the central processing unit 2 via the element impedance signal output terminal 41.

  In this way, the sensor control device 3 outputs the element impedance signal Srpvs representing the voltage change amount ΔVs from the element impedance signal output terminal 41 to the central processing unit 2.

  In the sensor control device 3, the first switch SW1 controls the voltage hold operation in the first operational amplifier OP1, that is, the sample hold circuit. Further, three second switches SW2 are provided to control on / off of current sources 63 and 65 for flowing a constant current -Iconst for measuring the resistance value (impedance detection) of the electromotive force cell 24. And one for controlling the signal hold operation in the signal hold circuit. Further, two third switches SW3 are provided, and current sources 64 and 66 for supplying a constant current + Iconst having a polarity opposite to that of the resistance value measurement current −Iconst passed through the second switch SW2 are turned on.・ Two for off control.

  The constant current + Iconst is a pulse signal having a polarity opposite to that of the current -Iconst. In this way, by passing a reverse polarity signal to the electromotive force cell 24, the internal electromotive force is affected by the orientation phenomenon of the solid electrolyte body constituting the electromotive force cell 24, and the internal electromotive force value according to the original oxygen concentration difference. It is possible to shorten the time from the abnormal state where no signal is output to the return to the normal state.

The switches SW1, SW2, and SW3 are controlled in a state (on state or off state) based on a command from the control unit 59.
The control unit 59 is mainly configured by a microcomputer including a CPU, a RAM, a ROM, an I / O interface, and the like. The control unit 59 executes switch control processing for controlling the states of the switches SW1, SW2, and SW3 based on a command from the central processing unit 2.

  The sensor control device 3 includes a built-in heater control unit 60 for controlling the heater of the gas sensor. The built-in heater control unit 60 can execute a heater control process for controlling the amount of power supplied to the heater by controlling the virtual heater voltage Vhi applied to the heater based on a command from the control unit 59. In the heater control process, the built-in heater control unit 60 controls, for example, the duty ratio of the pulsed virtual heater voltage Vhi, thereby controlling the amount of power supplied to the heater, and the gas sensor element to be heated by the heater. Control close to the target temperature can be performed.

  That is, the sensor control device 3 can detect the element impedance Rpvs (element temperature) of the gas sensor element 5a using the control unit 59, and can control the gas sensor element 5a to the target temperature using the built-in heater control unit 60. It is configured.

  However, as described above, in the sensor control system 1 of the present embodiment, the built-in heater control unit 60 is not connected to the heater 5b, and the main body that controls energization of the heater 5b is not the built-in heater control unit 60. The heater energization control circuit 6 is configured. That is, in the present embodiment, the built-in heater control unit 60 virtually performs the energization control of the heater 5b, but does not exhibit the function of heating the gas sensor element 5a.

[1-4. Control processing]
The mode setting process executed by the microcomputer 2a of the central processing unit 2 will be described with reference to the flowchart of FIG.

  The mode setting process is a process for setting each state of the virtual heater control mode and the Rpvs measurement function in the sensor control device 3 to either the ON state or the OFF state. Specifically, the microcomputer 2 a of the central processing unit 2 outputs the virtual heater control mode command Sh and the Rpvs measurement function command Sr to the sensor control device 3, so that the virtual heater control mode and the Rpvs measurement in the sensor control device 3 are output. Set each state of the function.

  When the mode setting process is started, the microcomputer 2a of the central processing unit 2 first initializes the sensor control unit 3 in S110. Specifically, an initialization command signal is transmitted to the sensor control device 3. When receiving the initialization command signal, the sensor control device 3 initializes information (internal flag, timer, etc.) used for various control processes for controlling the gas sensor element 5a of the gas sensor 5 and prepares for various control processes. .

  In S110, the heater drive fixed voltage Vhf as a command value is transmitted to the sensor control device 3. The heater driving fixed voltage Vhf is a command value of a voltage that the sensor control device 3 applies to the heater 5b during the fixed voltage control of the heater 5b. In the present embodiment, the heater driving fixed voltage Vhf is set to a value corresponding to the minimum value in the range of power supply that can be supplied to the heater 5b by the built-in heater control unit 60.

  In next S 120, the microcomputer 2 a of the central processing unit 2 transmits a start command signal to the heater energization control circuit 6. When the heater energization control circuit 6 receives the activation command signal, the heater energization control circuit 6 starts energization control processing of the heater 5b.

  In the next S130, the elapsed time counting process by the steady operation timer is started. In the steady operation timer, the elapsed time is repeatedly counted for each of a predetermined steady cycle T1 (T1 = 10 ms in the present embodiment) and a predetermined measurement cycle T2 (T2 = 100 ms in the present embodiment). .

  In the next S140, it is determined whether or not the steady cycle T1 has elapsed in the counting of the elapsed time by the steady operation timer. If affirmative determination is made, the process proceeds to S150. Wait until it has passed.

  When an affirmative determination is made in S140 and the process proceeds to S150, in S150, heater control information indicating the status of heater control in the heater energization control circuit 6 is acquired from the heater energization control circuit 6. This heater control information includes at least information indicating the state (high level, low level) of the heater voltage Vh (pulse energization signal).

  In next S160, it is determined whether or not the element impedance Rpvs (element temperature) of the gas sensor element 5a is measurable. If the determination is affirmative, the process proceeds to S180, and if the determination is negative, the process proceeds to S170. In S160, the voltage Vs of the electromotive force cell 24 received from the sensor control device 3 is compared with a predetermined measurable determination value Vth (in this embodiment, Vth = 4.2V). In S160, when the voltage Vs is equal to or lower than the measurable determination value Vth (Vs ≦ Vth), it is determined that the element impedance Rpvs is measurable (positive determination), and when the voltage Vs is larger than the measurable determination value Vth ( When Vs> Vth), it is determined that the element impedance Rpvs cannot be measured (negative determination).

When a negative determination is made in S160 and the process proceeds to S170, in S170, the virtual heater control mode command Sh and the Rpvs measurement function command Sr are each set to the OFF state.
When an affirmative determination is made in S160 and the process proceeds to S180, an Rpvs measurement determination process is executed in S180.

  When the Rpvs measurement determination process is started, as shown in FIG. 4, the microcomputer 2a of the central processing unit 2 first sets the heater voltage Vh under the heater PWM control by the heater energization control circuit 6 to the low level in S210. If the determination is affirmative, the process proceeds to S220. If the determination is negative, the process proceeds to S240.

  If an affirmative determination is made in S210 and the process proceeds to S220, it is determined in S220 whether or not the affirmative determination in S210 is the first time after the central processing unit 2 is activated. The process proceeds to S240.

  When a negative determination is made in S220 and the process proceeds to S240, in S240, it is determined whether or not the measurement cycle T2 has elapsed since the previous Rpvs measurement function command Sr was set in the ON state. Then, the process proceeds to S250.

  If an affirmative determination is made in S220 or an affirmative determination is made in S240 and the process proceeds to S230, in S230, the virtual heater control mode command Sh and the Rpvs measurement function command Sr are each set to the ON state.

  If a negative determination is made in S210 or a negative determination is made in S240 and the process proceeds to S250, in S250, the virtual heater control mode command Sh and the Rpvs measurement function command Sr are respectively set to the OFF state.

  When S230 or S250 ends, the process returns to the mode setting process and proceeds to S190. In S190, for each of the virtual heater control mode command Sh and the Rpvs measurement function command Sr, a command signal indicating the last set state (ON state, OFF state) is transmitted to the sensor control device 3. A command signal representing the state of the virtual heater control mode command Sh is referred to as a mode command signal Ssh, and a command signal representing the state of the Rpvs measurement function command Sr is referred to as a function command signal Ssr.

  When S190 ends, the process proceeds to S140 again. Thereafter, the microcomputer 2a of the central processing unit 2 repeatedly executes the processing from S140 to S190 until its own operation stops.

  Here, a timing chart showing respective states of the heater voltage Vh, the virtual heater control mode command Sh, and the Rpvs measurement function command Sr is shown in the upper region of FIG. 5 represents a waveform obtained by enlarging a part of the waveform of the upper region, the virtual heater voltage Vhi, the Rpvs measurement pulse signal Si (impedance measurement current -Iconst), and the AD sampling period Ts. Respectively.

  As shown in the upper region of FIG. 5, the heater voltage Vh is a pulse waveform voltage having a steady period T1, and FIG. 5 shows a pulse waveform in a state where the low level period and the high level period are equal. The virtual heater control mode command Sh and the Rpvs measurement function command Sr are set to a low level after being set to a high level over a steady period T1. The virtual heater control mode command Sh and the Rpvs measurement function command Sr are set to a high level for each measurement cycle T2.

Next, Rpvs measurement function control processing executed by the sensor control device 3 (specifically, the control unit 59) will be described with reference to the flowchart of FIG.
The Rpvs measurement function control process is a control process for controlling the detection operation of the element impedance Rpvs in the gas sensor element 5a based on the Rpvs measurement function command Sr from the central processing unit 2.

When the Rpvs measurement function control process is started, the sensor control device 3 first receives an Rpvs measurement function command Sr from the central processing unit 2 in S310.
In next S320, it is determined whether or not the Rpvs measurement function command Sr is in an ON state. If an affirmative determination is made, the process proceeds to S330, and if a negative determination is made, the process proceeds to S370.

When an affirmative determination is made in S320 and the process proceeds to S330, in S330, the timer count of the Rpvs measurement cycle T3 (T3 = 100 ms in the present embodiment) is started.
In the next S340, the output flag F1 of the Rpvs measurement pulse signal Si is set to the ON state.

  The output flag F1 is an internal flag used for determination processing in the Rpvs measurement pulse control processing described later. When a predetermined condition is established in the Rpvs measurement pulse control process, the sensor control device 3 outputs an Rpvs measurement pulse signal Si (impedance measurement current -Iconst) to the electromotive force cell 24 of the gas sensor element 5a.

In next S350, it is determined whether or not the Rpvs measurement function command Sr is in an OFF state. If an affirmative determination is made, the process proceeds to S370, and if a negative determination is made, the process proceeds to S360.
If a negative determination is made in S350 and the process proceeds to S360, it is determined in S360 whether or not the Rpvs measurement cycle T3 has elapsed. If an affirmative determination is made, the process proceeds to S330, and if a negative determination is made, the process proceeds to S350.

  If a negative determination is made in S320 or an affirmative determination is made in S350 and the process proceeds to S370, the output flag F1 of the Rpvs measurement pulse signal Si is set to an OFF state in S370. When the output flag F1 is turned off, the sensor control device 3 stops outputting the Rpvs measurement pulse signal Si to the electromotive force cell 24 of the gas sensor element 5a.

In the next S380, the timer count of the Rpvs measurement cycle T3 is stopped and the count value of the Rpvs measurement cycle T3 is cleared.
When S380 ends, the Rpvs measurement function control process ends. The Rpvs measurement function control process is repeatedly executed at a predetermined execution cycle.

Next, virtual heater control processing executed by the sensor control device 3 (specifically, the control unit 59) will be described with reference to the flowchart of FIG.
The virtual heater control process of the present embodiment is a control process for virtually executing the heater control operation based on the virtual heater control mode command Sh from the central processing unit 2. That is, in the virtual heater control process, the heater 5b is not actually energized and only the internal operation of the sensor control device 3 is executed.

  When the built-in heater control unit 60 of the sensor control device 3 is actually connected to the heater 5b, the sensor control device 3 can control the energization of the heater 5b by executing the virtual heater control process.

  When the virtual heater control process is started, the sensor control device 3 first receives the heater driving fixed voltage Vhf from the central processing unit 2 in S410. The heater driving fixed voltage Vhf is a command value from the central processing unit 2, and is a voltage that the sensor control device 3 applies to the heater 5b during fixed voltage control of the heater 5b.

  Note that when the mode setting process S110 of the central processing unit 2 is executed, the heater driving fixed voltage Vhf is transmitted to the sensor control device 3 by the operation of the central processing unit 2, and when the step S410 is executed, the sensor control device 3 The heater driving fixed voltage Vhf is transmitted from the central processing unit 2 to the sensor control device 3 by the operation.

  In the next S420, the virtual heater control mode command Sh is received from the central processing unit 2. In next S430, it is determined whether or not the virtual heater control mode command Sh is in the ON state. If an affirmative determination is made, the process proceeds to S440, and if a negative determination is made, the process proceeds to S480.

When an affirmative determination is made in S430 and the process proceeds to S440, timer counting of the heater control cycle T4 (T4 = 10 ms in the present embodiment) is started in S440.
In next S450, a heater energization control process is executed.

  When the heater energization control process is started, as shown in FIG. 8, the sensor control device 3 (control unit 59) first determines whether the heater control mode is “PI control” or “fixed voltage control” in S <b> 610. In the case of “PI control”, the process proceeds to S620, and in the case of “fixed voltage control”, the process proceeds to S630.

  In the present embodiment, the heater control mode is set to “fixed voltage control” according to a command from the central processing unit 2. If the built-in heater control unit 60 of the sensor control device 3 is actually connected to the heater 5b, the central processing unit 2 sets the heater control mode depending on whether or not the element impedance Rpvs can be measured. The command is output to the sensor control device 3. Specifically, when the element impedance Rpvs cannot be measured, the central processing unit 2 outputs a command for setting the heater control mode to “fixed voltage control” to the sensor control apparatus 3, and the element impedance When Rpvs can be measured, a command for setting the heater control mode to “PI control” is output to the sensor control device 3.

When it is determined as “PI control” in S610 and the process proceeds to S620, the latest element impedance Rpvs detected by the sensor control device 3 (control unit 59) is read in S620.
In next step S640, a PWM duty ratio for setting the element impedance Rpvs to the target impedance RT is calculated for the virtual heater voltage Vhi applied to the heater.

  When it is determined that the “fixed voltage control” is determined in S610 and the process proceeds to S630, the target fixed voltage Va stored in the storage unit of the sensor control device 3 (control unit 59) is read in S630. The target fixed voltage Va is set to a value corresponding to the heater driving fixed voltage Vhf acquired in S410, for example.

In the next S650, the PWM duty ratio is calculated so that the virtual heater voltage Vhi becomes the target fixed voltage Va while taking into consideration the battery voltage VB.
When S640 or S650 ends, in next S660, it is determined whether or not the calculated PWM duty ratio is equal to or less than the maximum value. If an affirmative determination is made, the process proceeds to S680, and if a negative determination is made, the process proceeds to S670.

If a negative determination is made in S660 and the process proceeds to S670, the PWM duty ratio is set to the maximum value in S670.
If an affirmative determination is made in S660 and the process proceeds to S680, it is determined in S680 whether or not the PWM duty ratio is equal to or greater than the minimum value. If an affirmative determination is made, the process proceeds to S700.

If a negative determination is made in S680 and the process proceeds to S690, the PWM duty ratio is set to a minimum value in S690.
When an affirmative determination is made in S680 or S670 or S690 is completed, the process proceeds to S700, and in S700, a heater PWM control process that is executed as a parallel process is started. The heater PWM control process is a control process for controlling the duty ratio of the virtual heater voltage Vhi that is output as a pulse to the heater based on the PWM duty ratio set in the processes from S610 to S690. The heater PWM control process is executed as a parallel process until it is stopped in S480 described later.

  In next S710, the Rpvs measurement pulse control process executed as parallel processing is started. When the Rpvs measurement pulse control process as the parallel process is started in S710, S710 ends and the heater energization control process ends. When the heater energization control process ends, the process returns to the virtual heater control process, and the process proceeds to S460.

Here, the Rpvs measurement pulse control process will be described with reference to the flowchart of FIG.
When the Rpvs measurement pulse control process is started, the sensor control device 3 (the control unit 59) first determines whether or not the heater PWM control is a low level output in S810, and proceeds to S820 if an affirmative determination is made. If the determination is negative, the same step is repeatedly executed to wait until the heater PWM control becomes a low level output. Specifically, in S810, it is determined whether or not the virtual heater voltage Vhi is a low level output.

  When an affirmative determination is made in S810 and the process proceeds to S820, it is determined whether or not the output flag F1 of the Rpvs measurement pulse signal Si is ON in S820. If the determination is affirmative, the process proceeds to S830, and if the determination is negative, the Rpvs measurement pulse control is performed. The process ends.

When an affirmative determination is made in S820 and the process proceeds to S830, the output flag F1 is set to an OFF state in S830.
In the next S840, the process waits until the Rpvs measurement waiting time Twa (Twa = 200 μsec in this embodiment) elapses.

  When the Rpvs measurement waiting time Twa elapses and the process proceeds to S850, it is determined whether or not it is the AD sampling time in S850. If the determination is affirmative, the process proceeds to S860, and if the determination is negative, the same step is repeatedly executed. Wait until the sampling time is reached. The sensor control device 3 executes an AD conversion process for converting an analog signal input from the outside into a digital signal every predetermined AD sampling cycle Ts (in this embodiment, 87 μsec). The execution timing of the AD conversion process executed every AD sampling period Ts is the AD sampling time. The AD sampling period Ts is determined based on the sampling frequency Fs of the sensor control device 3 (Fs = 11.5 kHz in the present embodiment).

  When an affirmative determination is made in S850 and the process proceeds to S860, the cell voltage Vs of the electromotive force cell 24 subjected to AD conversion is acquired and stored as the detection voltage Vs2 in S860. In the present embodiment, a sample hold circuit (see FIG. 1) having the first operational amplifier OP1 holds the detection voltage Vs2, and a storage unit (such as a RAM) provided in the control unit 59 stores the detection voltage Vs2.

In the next S870, the process waits until the pulse output waiting time Twb (Twb = 120 μsec in this embodiment) elapses.
When the pulse output waiting time Twb elapses and the process proceeds to S880, an Rpvs measurement pulse output process for outputting the Rpvs measurement pulse signal Si to the electromotive force cell 24 is executed in S880. In S880, specifically, the impedance measurement current -Iconst is output to the electromotive force cell 24 as the Rpvs measurement pulse signal Si.

  In the next S890, it is determined whether or not it is the AD sampling time. If an affirmative determination is made, the process proceeds to S900. If a negative determination is made, the same step is repeatedly executed to wait until the AD sampling time is reached.

  When an affirmative determination is made in S890 and the process proceeds to S900, in S900, the cell voltage Vs of the electromotive force cell 24 subjected to AD conversion is acquired and stored as the detected voltage Vs3, and the voltage change amount ΔVs (= Vs2−Vs3) is calculated. To do. In the present embodiment, the third operational amplifier OP3 outputs the voltage change amount ΔVs, and the control unit 59 calculates the voltage change amount ΔVs by the CPU while storing the detection voltage Vs2 in the storage unit (RAM or the like). This voltage change amount ΔVs can be used as an element impedance signal Srpvs representing the element impedance Rpvs of the electromotive force cell 24.

  In next S910, the low level output (impedance measurement current -Iconst) of the Rpvs measurement pulse signal Si is stopped, and after the signal stop period TR3 (see FIG. 5) has elapsed, the high level measurement is performed over the high level period TR2. A pulse signal Si (a constant current + Iconst having a polarity opposite to that of the current −Iconst) is output.

  As shown in FIG. 5, the Rpvs measurement pulse signal Si includes a current −Iconst output over the low level period TR1 and a constant current + Iconst output over the high level period TR2. By passing a constant current + Iconst of reverse polarity after the current −Iconst is energized, the internal electromotive force is affected by the orientation phenomenon of the solid electrolyte body constituting the electromotive force cell 24, and the internal electromotive force corresponding to the original oxygen concentration difference is affected. It is possible to shorten the time from the abnormal state in which the power value is not output to the return to the normal state.

When a negative determination is made in S820 or when S910 ends, the Rpvs measurement pulse control process ends.
That is, the Rpvs measurement pulse control process of the present embodiment is a control process for controlling the Rpvs measurement pulse signal Si based on the change state of the virtual heater voltage Vhi that is PWM-controlled with the duty ratio set in the virtual heater control process. is there. In S810, the switching timing (Lo edge timing) of the virtual heater voltage Vhi from the high level to the low level is detected, and in FIG. 5, the end timing of the duty on time Tht is detected. If the output flag F1 is in the ON state at that time (Yes determination in S820), the detection voltage Vs2 is detected at the AD sampling time after the Rpvs measurement waiting time Twa has elapsed (S860). Thereafter, when the pulse output waiting time Twb elapses, the Rpvs measurement pulse signal Si is output (S880), the detection voltage Vs3 is detected at the subsequent AD sampling time, and the voltage change amount ΔVs (= Vs2−Vs3) is calculated ( S900).

  When S710 ends and the heater energization control process ends, the process returns to the virtual heater control process. In S460, it is determined whether or not the virtual heater control mode command Sh is in the OFF state. If the determination is affirmative, the process proceeds to S480. If a negative determination is made, the process proceeds to S470.

  If a negative determination is made in S460 and the process proceeds to S470, it is determined in S470 whether or not the heater control period T4 has elapsed. If an affirmative determination is made, the process proceeds to S450, and if a negative determination is made, the process proceeds to S460.

If a negative determination is made in S430 or an affirmative determination is made in S460 and the process proceeds to S480, the heater PWM control is stopped in S480.
In the next S490, the timer count of the heater control cycle T4 is stopped and the count value of the heater control cycle T4 is cleared.

When S490 ends, the virtual heater control process ends. The virtual heater control process is repeatedly executed at a predetermined execution cycle.
As shown in the lower area of FIG. 5, the heater voltage Vh is changed from the high level to the low level, and the virtual heater control mode command Sh and the Rpvs measurement function command Sr output from the central processing unit 2 are in the OFF state. When the state is changed from ON to ON, the virtual heater voltage Vhi inside the sensor control device 3 is set from low level to high level after a predetermined communication time Tsp has elapsed.

  Thereafter, after the virtual heater voltage Vhi is set to the high level for the duty on time Tht corresponding to the heater driving fixed voltage Vhf transmitted from the central processing unit 2 to the sensor control device 3, the virtual heater voltage Vhi is set to the low level. The level is changed (S700). Thereafter, when the Rpvs measurement waiting time Twa elapses (S840), the cell voltage Vs (detected voltage Vs2) of the electromotive force cell 24 at the subsequent AD sampling time is acquired (S860).

  After that, when the pulse output waiting time Twb elapses, low level output of the Rpvs measurement pulse signal Si (output of resistance value current-Iconst) is started, and the cell voltage Vs of the electromotive force cell 24 at the subsequent AD sampling time is started. (Detection voltage Vs3) is acquired, and voltage change amount ΔVs (= Vs2−Vs3) is calculated (S900).

  Thereafter, the Rpvs measurement pulse signal Si is set to zero level, and when the signal stop period TR3 elapses, high level output of the Rpvs measurement pulse signal Si (output of constant current + Iconst) is started and when the high level period TR2 elapses. , Rpvs measurement pulse signal Si is set to zero level (S910).

  As described above, the sensor control device 3 executes the control process based on the virtual heater control mode command Sh and the Rpvs measurement function command Sr from the central processing unit 2 even if the sensor control device 3 itself does not control the energization of the heater 5b. By doing so, the voltage change amount ΔVs representing the state of the gas sensor element 5a can be detected. The sensor control device 3 can transmit the voltage change amount ΔVs to the central processing unit 2 as the element impedance signal Srpvs.

[1-5. effect]
As described above, when the sensor control system 1 controls the gas sensor 5 including the gas sensor element 5a and the heater 5b, the sensor control device 3 detects the state (element impedance Rpvs) of the gas sensor element 5a, and the heater energization control circuit. 6 is configured to control energization of the heater 5b. The central processing unit 2 sets the virtual heater control mode command Sh and the Rpvs measurement function command Sr based on the heater control state by the heater energization control circuit 6, thereby controlling the control state of the gas sensor 5 by the sensor control device 3. Set.

  When the virtual heater control mode command Sh and the Rpvs measurement function command Sr are both ON by executing the Rpvs measurement function control process and the Rpvs measurement pulse control process, the control unit 59 of the sensor control device 3 (S320). And a positive determination at S430), and the state (element impedance Rpvs) of the gas sensor element 5a is detected at the Rpvs measurement period T3 (S900).

  The control unit 59 of the sensor control device 3 executes the virtual heater control process, and executes the energization control of the heater 5b when the virtual heater control mode command Sh is in the ON state (Yes determination in S430) (S450). ) Is configured as follows.

  The microcomputer 2a of the central processing unit 2 executes the mode setting process, thereby outputting the virtual heater control mode command Sh and the Rpvs measurement function command Sr output to the sensor control device 3 to the heater 5b by the heater energization control circuit 6. It is configured to set based on the control state.

  The microcomputer 2a of the central processing unit 2 receives the heater voltage signal Svh from the heater energization control circuit 6, and when the heater voltage signal Svh, which is a pulse energization signal, switches from the high level to the low level (Yes in S210) ), The virtual heater control mode command Sh and the Rpvs measurement function command Sr are set to ON states (S230).

  In the sensor control system 1, since the central processing unit 2 (microcomputer 2a) sets the virtual heater control mode command Sh and the Rpvs measurement function command Sr based on the control state of the heater 5b by the heater energization control circuit 6, the sensor control The apparatus 3 (control part 59) can set the state detection time of the gas sensor element 5a according to an actual heater control state.

  In such a sensor control system 1, the heater 5b is not controlled by the sensor control device 3 (specifically, the control unit 59 and the built-in heater control unit 60) but by heater control by the heater energization control circuit 6 provided separately. Even if it is the structure which carries out electricity supply control, the state detection time of the gas sensor element 5a by the sensor control apparatus 3 (specifically control part 59) can be set appropriately. For this reason, by using the central processing unit 2, even if the heater energization control circuit 6 performs the heater control, the sensor control device 3 provided with the built-in heater control unit 60 is not modified. It becomes possible to detect the state of the gas sensor element 5a using.

  Therefore, according to the sensor control system 1 including the central processing unit 2, in controlling the gas sensor 5 including the gas sensor element 5 a and the heater 5 b, the heater energization control circuit 6 different from the sensor control device 3 is used to control the heater 5 b. Even when energization control is performed, the state detection timing of the gas sensor element 5a can be set to a time when the control state of the heater 5b by the heater energization control circuit 6 is considered.

  Next, in the central processing unit 2, the heater voltage signal Svh, which is a pulse energization signal, is changed from a high level to a low level as detection trigger information for determining the switching timing of the virtual heater control mode command Sh and the Rpvs measurement function command Sr. A signal for switching to the level (in other words, an OFF edge signal indicating the switching time of the heater energization state from ON to OFF) is used (S210).

  As described above, the microcomputer 2a of the central processing unit 2 uses the heater energization control circuit 6 by using the OFF edge signal representing a specific energization state in the heater voltage signal Svh, which is a pulse energization signal, as detection trigger information. Can be determined when the output of the heater voltage Vh to the heater 5b is in the OFF state. Therefore, the microcomputer 2a can set the virtual heater control mode command Sh and the Rpvs measurement function command Sr to the ON state based on the time when the output of the heater voltage Vh is in the OFF state, and the sensor control device 3 (the control unit 59). The state detection timing of the gas sensor element 5a can be set.

  Thereby, the sensor control apparatus 3 (control part 59) can perform the state detection (detection of element impedance Rpvs) of the gas sensor element 5a at an appropriate timing set based on the actual heater control state.

  Next, in the sensor control system 1, the sensor control device 3 uses the target fixed voltage Va used for fixed voltage control (S 650) by the control unit 59 and the built-in heater control unit 60 as a command value from the central processing unit 2. The heater driving fixed voltage Vhf is set.

  That is, the sensor control device 3 is configured to receive the heater driving fixed voltage Vhf, which is a command value of the target fixed voltage Va used for the fixed voltage control (S650), from the central processing unit 2 (S110, S410). ).

  Then, the microcomputer 2a of the central processing unit 2 fixes the heater drive in which a value corresponding to the minimum value is set in the range of power supply that can be supplied to the heater 5b by the sensor control device 3 (built-in heater control unit 60). The voltage Vhf is output.

  When the central processing unit 2 (microcomputer 2a) outputs such a heater driving fixed voltage Vhf, in the virtual control by the control unit 59 and the built-in heater control unit 60 of the sensor control device 3, the energization to the heater is PWM. The energization time (duty on time Tht) to the heater in the case of control can be set to the shortest. Thereby, after the virtual heater control by the control unit 59 and the built-in heater control unit 60 is started, the time until the energization to the heater is stopped can be set to the shortest. Thus, the state detection timing of the gas sensor element 5a (detection timing of the element impedance Rpvs) can be set to an early time.

  As a result, the sensor control system 1 including the central processing unit 2 receives the OFF edge signal of the heater voltage signal Svh from the heater energization control circuit 6, and then the gas sensor by the sensor control device 3 (specifically, the control unit 59). The time required for detecting the state of the element 5a can be set to the shortest.

  Next, when both the virtual heater control mode command Sh and the Rpvs measurement function command Sr are changed from the OFF state to the ON state (positive determination in S320, positive determination in S430), the control unit 59 of the sensor control device 3 The state (element impedance Rpvs) of the gas sensor element 5a is detected (S340, S450, S710).

  For this reason, the central processing unit 2 does not adopt a configuration in which the individual signal indicating the state detection timing of the gas sensor element 5a is output to the sensor control device 3, and the switching timing of the virtual heater control mode command Sh and the Rpvs measurement function command Sr. The timing for detecting the state of the gas sensor element 5a can be transmitted to the sensor control device 3 using (timing for changing from the OFF state to the ON state).

  Thereby, since modification of the sensor control device 3 is not required, the central processing unit 2 can set the state detection timing of the gas sensor element 5a while using the existing sensor control device 3.

  In addition, after the controller 59 of the sensor control device 3 detects the state of the gas sensor element 5a (element impedance Rpvs), the virtual heater control mode command Sh and the Rpvs measurement function command Sr are both in the ON state. It is configured to detect the state of the gas sensor element 5a at the Rpvs measurement cycle T3 (repetitively execute the processing from S330 to S360).

As described above, by repeatedly detecting the state of the gas sensor element 5a, the state after the change can be detected even when the state of the gas sensor element 5a changes.
[1-5. Correspondence of wording]
Here, the correspondence between words will be described.

  The sensor control system 1 corresponds to a sensor control system, the central processing unit 2 corresponds to a control state setting device, the sensor control device 3 corresponds to a sensor control unit, the gas sensor 5 corresponds to a sensor, and the gas sensor element 5a It corresponds to a sensor element, the heater 5b corresponds to a heater unit, and the heater energization control circuit 6 corresponds to an individual heater control unit.

  The virtual heater control mode command Sh corresponds to the heater control mode command, the Rpvs measurement function command Sr corresponds to the element state detection mode command, and the control unit 59 that executes the Rpvs measurement function control process and the Rpvs measurement pulse control process is the element state. The control unit 59 and the built-in heater control unit 60 that correspond to the detection unit and execute the virtual heater control process correspond to the built-in heater control unit, and the microcomputer 2a that executes the mode setting process corresponds to the mode setting unit.

  The heater voltage signal Svh that switches from the high level to the low level corresponds to detection trigger information and an OFF edge signal, the heater driving fixed voltage Vhf corresponds to a power command value, and the microcomputer 2a that executes S110 corresponds to a power command value output unit. The Rpvs measurement period T3 corresponds to a predetermined detection period.

[2. Other Embodiments]
As mentioned above, although embodiment of this indication was described, this indication is not limited to the above-mentioned embodiment, and can be carried out in various modes in the range which does not deviate from the gist of this indication.

  For example, in the above embodiment, as the central processing unit 2 (microcomputer 2a), two commands are simultaneously changed when changing the states of the virtual heater control mode command Sh and the Rpvs measurement function command Sr (S230). Explained. However, the central processing unit 2 (microcomputer 2a) is not limited to such a configuration, and may be configured to change the virtual heater control mode command Sh and the Rpvs measurement function command Sr at different timings. Even in such a case, the sensor control device 3 (control unit 59) detects the state (element impedance Rpvs) of the gas sensor element 5a when both of the two commands are changed to the ON state. .

  Moreover, in the said embodiment, although element impedance Rpvs was detected as a state of the gas sensor element 5a, you may make it detect admittance etc. as a state of the gas sensor element 5a.

  Next, the function of one component in the above embodiment 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 the said embodiment. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

  In addition to the above-described microcomputer, there are various systems such as a system including the microcomputer as a constituent element, a program for causing the computer to function as the microcomputer, a non-transition actual recording medium such as a semiconductor memory in which the program is recorded, various calculation methods, etc. The present disclosure can also be realized in the form.

  DESCRIPTION OF SYMBOLS 1 ... Sensor control system, 2 ... Central processing unit (MCU), 2a ... Microcomputer (microcomputer), 3 ... Sensor control apparatus, 5 ... Gas sensor, 5a ... Gas sensor element, 5b ... Heater, 5c ... Heating resistor, 6 ... heater energization control circuit, 14 ... pump cell, 24 ... electromotive force cell, 59 ... control unit, 60 ... built-in heater control unit.

Claims (5)

A control state setting device for setting a control state of the sensor by a sensor control unit that controls a sensor including a sensor element and a heater unit,
The sensor control unit
An element state that detects the state of the sensor element when both the heater control mode command and the element state detection mode command are mode ON commands based on an external heater control mode command and an element state detection mode command A detection unit;
Based on the heater control mode command, when the heater control mode command is a mode ON command, a built-in heater control unit that controls the heater unit;
With
The heater section is configured to be energized and controlled by a pulse energization signal output from an individual heater controller provided separately from the sensor controller, not the built-in heater controller.
The control state setting device
A mode setting unit that sets the heater control mode command to be output to the sensor control unit and the element state detection mode command based on a pulse energization signal to the heater unit by the individual heater control unit;
When the mode setting unit receives detection trigger information representing a specific energization state determined in advance among the pulse energization signals output from the individual heater control unit, the heater that outputs to the sensor control unit Each of the control mode command and the element state detection mode command is set to the ON state.
Control state setting device. The detection trigger information is an OFF edge signal indicating a switching time from ON to OFF in the pulse energization signal.
The control state setting device according to claim 1. The sensor control unit is configured to receive from the outside a power command value that is a command value of the amount of power supplied to the heater unit by the built-in heater control unit,
The control state setting device includes a power command value output unit that outputs, to the sensor control unit, a minimum value in a range of power supply that can be supplied to the heater unit by the built-in heater control unit as the power command value. Comprising
The control state setting device according to claim 1. The element state detection unit detects the state of the sensor element when both the heater control mode command and the element state detection mode command are changed from a mode OFF command to a mode ON command, and then the heater control mode During the period in which both the command and the element state detection mode command are mode ON commands, the state of the sensor element is detected at a predetermined detection cycle.
The control state setting device according to any one of claims 1 to 3. A sensor control unit for controlling a sensor including a sensor element and a heater unit;
A control state setting device for setting a control state of the sensor by the sensor control unit;
A sensor control system comprising:
The sensor control unit
An element state that detects the state of the sensor element when both the heater control mode command and the element state detection mode command are mode ON commands based on an external heater control mode command and an element state detection mode command A detection unit;
A built-in heater control unit that controls the heater unit when the heater control mode command is a mode ON command based on the heater control mode command;
The heater section is configured to be energized and controlled by a pulse energization signal output from an individual heater controller provided separately from the sensor controller, not the built-in heater controller.
The control state setting device is the control state setting device according to any one of claims 1 to 4.
Sensor control system.