Gas sensor terminal abnormality detection device

Abstract

To provide a gas sensor terminal abnormality detection device capable of determining normality / ground fault of an AFR terminal independently.SOLUTION: A predetermined voltage application circuit 23 applies predetermined voltage to an AFC terminal Tm to enable a normal operation of an oxygen sensor 60. A test voltage application circuit 24 allows connection to an AFR terminal Tp only during test detection of a terminal state of the AFR terminal Tp and applies test voltage as voltage for state detection of the AFR terminal Tp. An AFR ground fault determination section 10a determines normality / ground fault of the AFR terminal Tp on the basis of the application of the test voltage by the test voltage application circuit 24.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a gas sensor terminal abnormality detection device.

Background Art

[0002] A circuit for controlling a gas sensor is provided with terminals for connecting the gas sensor, and an abnormality detection circuit for detecting a ground fault abnormality of the positive terminal and the negative terminal is provided (see, for example, Patent Document 1). When the gas sensor is in an active state, its impedance significantly decreases. Therefore, in a conventional circuit, when the AFC terminal of the gas sensor is grounded, the AFR terminal at the other end may be regarded as a ground potential even when it is normal. For this reason, there is a problem that the AFR terminal cannot be individually determined as normal / grounded.

[0003] When continuing to control using the positive terminal and the negative terminal as in the technique described in Patent Document 1, if the positive terminal (corresponding to the AFR terminal) is also regarded as a ground potential when the negative terminal (corresponding to the AFC terminal) is grounded, even if the voltage across both ends of the gas sensor is read, it will always be a lean determination. It becomes difficult for the control device to perform control to make it rich in order to avoid deterioration of the exhaust gas. During limp home, there is a possibility that the exhaust gas purification becomes insufficient, or it may lead to deterioration of drivability and ignition performance, which is not preferable.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present disclosure is to provide a gas sensor terminal abnormality detection device capable of individually determining whether the AFR terminal is normal / grounded.

Means for Solving the Problems

[0006] The invention described in claim 1 relates to a gas sensor terminal abnormality detection device that detects a short-circuit abnormality at the AFR terminal when energizing an oxygen sensor connected between the AFR terminal and the AFC terminal. According to the invention described in claim 1, the predetermined voltage application circuit applies a predetermined voltage to the AFC terminal to enable the oxygen sensor to operate normally. The test voltage application unit is connected to the AFR terminal only when testing the terminal state of the AFR terminal and applies a test voltage as a voltage for detecting the state of the AFR terminal.

[0007] The AFR ground fault determination unit determines whether the AFR terminal is normal or ground faulted based on the application of a test voltage by the test voltage application unit. According to the invention described in claim 1, the test voltage application unit applies a test voltage to the AFR terminal, and the AFR ground fault determination unit determines whether the AFR terminal is normal or ground faulted based on the application of the test voltage, so it is possible to determine whether the AFR terminal is normal or ground faulted by itself. The system also includes an AFC ground fault determination unit that determines whether the AFC terminal is normal or has a ground fault. The test voltage application unit applies a voltage for detecting the state of the AFC terminal only when a ground fault is detected at the AFC terminal. [Brief explanation of the drawing]

[0008] [Figure 1] An schematic electrical configuration diagram showing the control system in the first embodiment. [Figure 2] A flowchart illustrating the processing when an anomaly is detected in the first embodiment. [Figure 3] Diagram illustrating the normal operation and ground fault operation of the AFR terminal and AFC terminal in the first embodiment. [Figure 4] An schematic electrical configuration diagram showing the oxygen sensor abnormality detection system in the second embodiment. [Modes for carrying out the invention]

[0009] Several embodiments of the gas sensor terminal abnormality detection device will be described below with reference to the drawings. In the embodiments described below, identical or similar components in each embodiment may be denoted by the same or similar reference numerals and their descriptions may be omitted.

[0010] (First Embodiment) The first embodiment will be described with reference to Figures 1 to 3. As shown in Figure 1, the control system 101 is mainly composed of an electronic control unit 102 equipped with a microcomputer 10 and a control IC 20. The electronic control unit 102 is configured as a gas sensor terminal abnormality detection device. In addition to the electronic control unit 102, the control system 101 is configured by connecting a fuel injection system circuit 40 and a diagnostic display circuit 50 to the vehicle. An oxygen sensor 60 is connected to the control IC 20 as a gas sensor.

[0011] The oxygen sensor 60 is used as an air-fuel ratio sensor to detect lean conditions (where the ratio of fuel to air is lower than the stoichiometric air-fuel ratio) and rich conditions (where the ratio of fuel to air is higher than the stoichiometric air-fuel ratio). In addition to being an air-fuel ratio sensor, the oxygen sensor 60 can be used for various other applications to determine oxygen concentration.

[0012] The oxygen sensor 60 comprises a solid electrolyte layer made of zirconia or the like, a diffusion resistance layer made of porous ceramic or the like, and an anode electrode / cathode electrode sandwiching the solid electrolyte layer. The oxygen sensor 60 is a sensor element for detecting the presence or absence of oxygen gas in exhaust gas and the concentration of oxygen gas. Exhaust gas is generally generated from internal combustion engines that produce power by burning fossil fuels, such as gasoline, diesel fuel, kerosene, and natural gas. Exhaust gas is supplied to the anode electrode on the exhaust side, and air is supplied to the cathode electrode.

[0013] When the solid electrolyte layer is heated by exhaust gas or a heater, it conducts current according to the amount of ionized oxygen that passes through it. When the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, the amount of oxygen that moves from the anode electrode to the cathode electrode changes according to the concentration of oxygen remaining in the exhaust gas supplied to the anode electrode. When the air-fuel ratio is richer than the stoichiometric air-fuel ratio, the amount of oxygen that moves from the cathode electrode to the anode electrode depends on the concentration of unburned gas in the exhaust gas. As a result, the oxygen sensor 60 outputs a limiting current whose magnitude is based on the oxygen concentration and unburned gas concentration in the exhaust gas.

[0014] When heating by exhaust or heater is stopped, the oxygen sensor 60 is exposed to low temperatures. When the oxygen sensor 60 is in a low temperature state, the rate of oxygen movement through the solid electrolyte layer decreases. As the rate of oxygen movement decreases, the maximum current decreases. For example, at temperatures of 500-600°C or higher, it enters an active state where current flows up to the limit current. Conversely, below the temperature at which it enters an active state, it enters an inactive state where current does not flow up to the limit current due to the decrease in current. In addition, the impedance of the oxygen sensor 60 increases as the rate of oxygen movement decreases.

[0015] A capacitor 61 is connected to the cathode electrode side of the oxygen sensor 60, and a capacitor 62 and a resistor 63 are connected in parallel to the anode electrode side of the oxygen sensor 60. This stabilizes the applied voltage.

[0016] The microcontroller 10 is a microcontroller equipped with a processor, memory such as ROM and RAM, I / O, etc. It issues commands to the control IC 20, which then applies a sweep voltage to the oxygen sensor 60 and receives the sensor signal from the oxygen sensor 60 through the control IC 20.

[0017] The control IC 20 is a semiconductor device equipped with an AFC terminal Tm connected to the cathode electrode of the oxygen sensor 60, and an AFR terminal Tp connected to the anode electrode of the oxygen sensor 60. The AFR terminal Tp and AFC terminal Tm are provided to acquire the terminal voltage or current of the oxygen sensor 60 as a sensor signal when a sweep voltage is applied to the oxygen sensor 60. The electronic control device 102 functions as a gas sensor terminal abnormality detection device that detects short-circuit abnormalities of the AFR terminal Tp and AFC terminal Tm.

[0018] The control IC 20 comprises a control unit 21, a predetermined voltage application circuit 23, a test voltage application circuit 24 as a test voltage application unit, a current detection circuit 25, a current-voltage detection changeover switch 26, a current-voltage detection circuit 27, a terminal voltage detection circuit 28, and a sweep voltage application circuit 30. The control unit 21 is composed of a predetermined digital circuit equipped with a memory 21a.

[0019] The predetermined voltage application circuit 23 is a circuit that applies a predetermined voltage V0 to the AFC terminal Tm to enable the normal operation of the oxygen sensor 60. The predetermined voltage application circuit 23 includes a DA converter 23a and a buffer 23b.

[0020] The DA converter 23a inputs a command digital value from the control unit 21 and performs analog conversion. The buffer 23b buffers the analog output of the DA converter 23a and applies the predetermined voltage V0 to the cathode electrode of the oxygen sensor 60 through the current detection circuit 25 and the AFC terminal Tm. The current detection circuit 25 is composed of a resistor connected in series between the buffer 23b and the AFC terminal Tm.

[0021] The test voltage application circuit 24 is a circuit that is connected to the AFR terminal Tp only when detecting the terminal state of the AFR terminal Tp and applies a test voltage Vtest as a voltage for detecting the state of the AFR terminal Tp. The test voltage application circuit 24 includes a DA converter 24a, a buffer 24b, and a switch 24c.

[0022] The DA converter 24a inputs a command digital value from the control unit 21 and performs analog conversion. The buffer 24b buffers the analog output of the DA converter 24a and applies the test voltage Vtest to the anode electrode of the oxygen sensor 60 through the switch 24c and the AFR terminal Tp. Note that the test voltage application circuit 24 does not apply the test voltage Vtest as a voltage for state detection to the AFR terminal Tp unless the switch 24c is turned on. The switch 24c is controlled to be turned on and off by the control unit 21.

[0023] The current-voltage detection switch 26 is a switch that switches between acquiring the detected current of the current detection circuit 25 and acquiring the inter-terminal voltage between the AFC terminal Tm and the AFR terminal Tp. The current-voltage detection switch 26 can be switched and controlled by the control unit 21.

[0024] The current-voltage detection circuit 27 receives the switching detection signal from the current-voltage detection changeover switch 26, converts it into digital data, and outputs it to the control unit 21. The current-voltage detection circuit 27 includes an amplifier 27a and an AD converter 27b.

[0025] Amplifier 27a amplifies when it receives a switching detection signal from the current-voltage detection selector switch 26. The AD converter 27b receives the amplified output of amplifier 27a, performs AD conversion, and outputs it to the control unit 21. As a result, the control unit 21 can acquire the detected current from the current detection circuit 25 and the terminal voltage between the AFC terminal Tm and the AFR terminal Tp by controlling the switching of the current-voltage detection selector switch 26.

[0026] The terminal voltage detection circuit 28 is a circuit that individually detects the voltage of the AFC terminal Tm or the voltage of the AFR terminal Tp. The terminal voltage detection circuit 28 comprises a multiplexer 28a and an AD converter 28b. The multiplexer 28a receives the voltage of the AFC terminal Tm and the voltage of the AFR terminal Tp, and under the control of the control unit 21, outputs one of the voltages to the AD converter 28b. The AD converter 28b receives the output voltage of the multiplexer 28a, performs digital conversion, and outputs it to the control unit 21. As a result, the control unit 21 can individually acquire the voltage of the AFC terminal Tm and the voltage of the AFR terminal Tp.

[0027] The sweep voltage application circuit 30 is a circuit that applies a sweep voltage to the anode electrode of the oxygen sensor 60 through the AFR terminal Tp during normal operation. The sweep voltage application circuit 30 comprises a DA converter 30a and a sweep voltage generation unit 30b. The DA converter 30a receives a command digital value from the control unit 21, converts it to an analog value, and outputs it to the sweep voltage generation unit 30b. The sweep voltage generation unit 30b receives the analog conversion output, generates a sweep voltage based on the output value, and applies it to the anode electrode of the oxygen sensor 60 through the AFR terminal Tp.

[0028] During normal operation, the predetermined voltage application circuit 23 applies a voltage to the cathode electrode of the oxygen sensor 60 via the AFC terminal Tm according to the command digital value input from the control unit 21. The sweep voltage generation unit 30b also applies a sweep voltage to the anode electrode of the oxygen sensor 60 via the AFR terminal Tp. At this time, the control unit 21 acquires the terminal voltages of the AFC terminal Tm and the AFR terminal Tp, and the detected current of the current detection circuit 25 by switching the current voltage detection changeover switch 26.

[0029] When the microcontroller 10 receives this data from the control unit 21 via the I / F 22, it calculates the impedance of the oxygen sensor 60 by dividing the voltage change ΔV of the terminal voltage when a sweep voltage is applied by the current change ΔI of the detected current of the current detection circuit 25.

[0030] This allows the state of the oxygen sensor 60 to be detected during normal operation. The microcontroller 10 can detect the impedance of the oxygen sensor 60 in correspondence with the temperature state of the oxygen sensor 60 and use this to control the power supply of a heater (not shown) for temperature control of the oxygen sensor 60. In addition, the microcontroller 10 can detect the deterioration state of the oxygen sensor 60 by calculating its impedance.

[0031] During normal operation, the microcontroller 10 receives the sensor signal from the oxygen sensor 60 to determine the fuel-to-air ratio, decides whether the mixture is lean or rich, and performs fuel feedback control to the fuel injection system circuit 40. This enables exhaust gas purification control and control that ensures drivability. The microcontroller 10 also performs abnormality detection processing for normal / short circuit status of the AFC terminal Tm and AFR terminal Tp. In this process, the microcontroller 10 stores, detects, and determines the abnormality values ​​for the AFC terminal Tm and AFR terminal Tp.

[0032] The microcontroller 10 functions as an AFR ground fault determination unit 10a, which determines whether the AFR terminal Tp is normal or has a ground fault based on the application of a state detection voltage by the test voltage application circuit 24. The microcontroller 10 also functions as an AFC ground fault determination unit 10b, which determines whether or not the AFC terminal Tp has a ground fault.

[0033] The operation for determining whether the AFC terminal Tm and AFR terminal Tp are normal or short-circuited will be explained with reference to Figures 2 and 3. During normal operation of S0 as shown in Figure 2, the microcontroller 10 detects the state of the oxygen sensor 60, calculates the air-fuel ratio, and performs fuel feedback control to the fuel injection system circuit 40. During this time, in order to calculate the impedance of the oxygen sensor 60, the predetermined voltage application circuit 23 continuously outputs a predetermined voltage to the AFC terminal Tm, and the sweep voltage generation unit 30b applies a sweep voltage to the AFR terminal Tp.

[0034] For example, when an abnormality is detected at a certain timing, the control unit 21 stops outputting a command digital value to the sweep voltage application circuit 30, and in S1, the sweep voltage generation unit 30b stops outputting the sweep voltage. The predetermined voltage application circuit 23 continues to output the predetermined voltage.

[0035] When a predetermined voltage is applied to the AFC terminal Tm through the current detection circuit 25, the control unit 21 detects the voltage of the AFC terminal Tm through the terminal voltage detection circuit 28 in S2. In S3, the control unit 21 determines whether or not the AFC terminal Tm is ground faulted. The control unit 21 determines whether or not the voltage V of the AFC terminal Tm is greater than the AFC threshold Vm, and if it is greater than the AFC threshold Vm, in S5 it determines that the AFC terminal Tm is not ground faulted and is normal. The control unit 21 then stores in memory 21a that the AFC terminal Tm is normal. If the AFC terminal Tm is normal, the process proceeds to S7, the operation at which point will be described later.

[0036] Conversely, if the voltage of the AFC terminal Tm in S3 is equal to or lower than the AFC threshold value Vm, it is determined that the AFC terminal Tm is grounded and abnormal in S4. At this time, the control unit 21 stores in the memory 21a that the AFC terminal Tm is grounded.

[0037] <When the ground connection of the AFC terminal Tm is determined> When the ground connection of the AFC terminal Tm is determined, the control unit 21 changes the detection mode in S6 and switches the switch 24c of the test voltage application circuit 24 from off to on. Then, the control unit 21 applies a test voltage Vtest to the AFR terminal Tp by outputting a command digital value to the DA converter 24a.

[0038] Note that, even after it is determined that the AFC terminal Tm is normal (S5), the process of S6 may be continuously executed. However, it is desirable that the control unit 21 applies a voltage for state detection as a test voltage from the test voltage application circuit 24 to the AFR terminal Tp only when the ground connection of the AFC terminal Tm is determined. This is because, when it is determined that the AFC terminal Tm is normal (S5), the effects obtained by applying the test voltage Vtest for state detection in S6, the effects according to the present application, cannot be obtained. If it is determined that the AFC terminal Tm is normal, it is advisable to skip the process of S6 and proceed to the process of S7. In this case, unnecessary operations, here the process of S6 can be skipped and the detection speed can be increased.

[0039] Furthermore, it is desirable to set a test voltage Vtest, which is set to be below the blackening occurrence voltage VL of the oxygen sensor 60, as the voltage for detecting the state of the AFR terminal Tp from the test voltage application circuit 24 and apply it. It is desirable that the test voltage Vtest be a voltage that can avoid sensor damage caused by blackening. Blackening is a state in which an electrode reaction occurs through the solid electrolyte layer, and it is a phenomenon in which oxygen deficiency occurs in the solid electrolyte layer and metal oxides in the solid electrolyte are reduced. When blackening occurs, the ionic conductivity, which is a characteristic of the solid electrolyte, deteriorates and the pumping performance decreases. Normally, if it rises above 1.6V, there is a risk of adverse effects such as blackening occurring due to the reduction action. Here, the test voltage Vtest is set to a voltage below the blackening occurrence voltage VL and is set and applied as the voltage for detecting the state of the AFR terminal Tp. This prevents the occurrence of blackening. The normally defined blackening occurrence voltage VL is the voltage between the sensor terminals Tm-Tp, but it is compared by considering it as a ground reference voltage, assuming that the AFC terminal Tm is ground faulted. Furthermore, all comparison voltages other than the blackening occurrence voltage VL (predetermined voltage V0, test voltage Vtest, AFR threshold VT) are ground-referenced voltages.

[0040] Then, in S7, the control unit 21 acquires the voltage of the AFR terminal Tp with the test voltage Vtest applied to it. The control unit 21 determines whether the voltage of the AFR terminal Tp is greater than the AFR threshold VT. The AFR threshold VT is preset to a voltage less than a predetermined voltage V0, less than the blackening occurrence voltage VL, and less than the test voltage Vtest. If the AFR terminal Tp is not grounded, the voltage of the AFR terminal Tp will, in principle, be held at the test voltage Vtest. Therefore, if the voltage of the AFR terminal Tp is greater than the AFR threshold VT, the control unit 21 determines in S10 that the AFR terminal Tp is not grounded and is normal. The control unit 21 then stores the fact that the AFR terminal Tp is normal in the memory 21a.

[0041] Conversely, if the voltage of the AFR terminal Tp at S8 is less than or equal to the AFR threshold value VT, it is determined that the AFR terminal Tp is grounded and abnormal at S9. At this time, the control unit 21 stores in the memory 21a that the AFR terminal Tp is grounded. Thereafter, the control unit 21 transmits the abnormality determination content stored in the memory 21a to the microcomputer 10 through the I / F 22. When the microcomputer 10 receives this abnormality determination content, it executes soft control based on this determination content at S11.

[0042] <When the AFC terminal Tm is determined to be normal> If the AFC terminal Tm is determined to be normal at S5, the control unit 21 proceeds to S7 to acquire the voltage of the AFR terminal Tp, and performs a ground fault determination on the AFR terminal Tp at S8. At this time, the control unit 21 determines whether the voltage of the AFR terminal Tp exceeds the threshold value VT at S8. If the AFR terminal Tp is grounded, a ground fault determination is made at S9 and the fact is stored in the memory 21a. If the AFR terminal Tp is not grounded, a normal determination is made at S10 and the fact is stored in the memory 21a. In this case, the above-described test voltage Vtest can be determined without being applied to the AFR terminal Tp. Thereafter, the control unit 21 transmits the abnormality determination content stored in the memory 21a to the microcomputer 10 through the I / F 22. When the microcomputer 10 receives this abnormality determination content, it executes soft control based on this determination content at S11.

[0043] Fig. 3 collectively shows the processing operations when each of the AFC terminal Tm and the AFR terminal Tp is normal / grounded. When both the AFC terminal Tm and the AFR terminal Tp are normal, the microcomputer 10 neither issues a diagnosis display command nor performs fail-safe control.

[0044] Even when the AFC terminal Tm is determined to be normal, if only the AFR terminal Tp is experiencing a ground fault, the voltage at the AFR terminal Tp is detected as 0V. Therefore, the microcontroller 10 forcibly determines that the AFR terminal Tp is experiencing a ground fault. Because a ground fault has been determined, the microcontroller 10 displays a diagnostic error on the diagnostic display circuit 50, stops the fuel feedback control during normal operation, and also implements fail-safe control.

[0045] The microcontroller 10 switches to limp home mode in fail-safe control and sends a control request to the fuel injection system circuit 40 to perform limp home. In limp home mode, some of the vehicle's functions are limited because feedback control is stopped. In limp home mode, the fuel injection system circuit 40 controls the vehicle to travel at a low speed, which minimizes damage to the internal combustion engine and other components, while allowing the vehicle occupants to return home safely.

[0046] Furthermore, if both the AFC terminal Tm and the AFR terminal Tp are determined to be ground fault abnormalities, the microcontroller 10 detects that the voltages at both AFC terminal Tm and AFR terminal Tp are 0V. In this case as well, the microcontroller 10 forcibly determines that both AFC terminal Tm and AFR terminal Tp are ground fault abnormalities. Because a ground fault abnormality has been determined, the microcontroller 10 displays a diagnostic error on the diagnostic display circuit 50, stops the fuel feedback control during normal operation, and also implements fail-safe control.

[0047] The microcontroller 10 switches to limp home mode in fail-safe control and sends a control request to the fuel injection system circuit 40 to perform limp home. Because feedback control is stopped, some of the vehicle's functions are limited. In limp home mode, the fuel injection system circuit 40 controls low-speed driving to minimize damage to the internal combustion engine and other parts, while allowing the vehicle occupants to return home safely.

[0048] Furthermore, if the AFC terminal Tm experiences a ground fault abnormality even though the AFR terminal Tp is not faulted to ground, the microcontroller 10 detects the voltage of the AFC terminal Tm as 0V. However, since the control unit 21 compares the voltage of the AFR terminal Tp with a threshold VT, it can determine that the AFR terminal Tp is normal without misjudging it as a ground fault as in conventional circuits. Therefore, the microcontroller 10 can continue fuel feedback control based on lean / rich air-fuel ratio based on the results obtained from the oxygen sensor 60 without changing to limp home mode.

[0049] In other words, when the AFC terminal Tm is determined to be ground fault and the AFR terminal Tp is determined to be normal, the microcontroller 10 and the fuel injection system circuit 40 do not perform fail-safe control. Although the control unit 21 has determined the AFR terminal Tp to be normal, it has determined the AFC terminal Tm to be ground fault abnormal, so the microcontroller 10 issues a warning to the outside by outputting a diagnostic to the diagnostic display circuit 50.

[0050] This allows for the option of not performing fail-safe control while still outputting a diagnostic signal related to a ground fault abnormality at the AFC terminal Tm. Therefore, if fail-safe control is not performed, the same control as during normal operation, i.e., exhaust gas purification control and control that ensures drivability, can be executed.

[0051] <Summary> According to this embodiment, a test voltage application circuit 24 is provided that applies a test voltage Vtest to the AFR terminal Tp via a switch 24c. With this configuration, it is possible to determine whether or not the AFR terminal Tp is ground faulted. In this case, even when the AFC terminal Tm is determined to be ground faulted, the test voltage Vtest that can determine normal operation when the AFR terminal Tp is normal can be applied. As a result, the normal / ground fault status of the AFR terminal Tp can be determined independently, and the ground fault state of the AFC terminal Tm and the normal state of the AFR terminal Tp, which could not be determined with conventional circuits, can be detected.

[0052] As in this embodiment, if the AFR terminal Tp can be independently identified as normal or ground fault, proper fuel feedback control can be performed to ensure ignition. Moreover, diagnostic display becomes possible, and even in limp home mode, exhaust gas purification and drivability performance can be improved. This allows for rich / lean control, thereby increasing the degree of freedom in vehicle control. As a result, warnings can be notified to the outside while maintaining a high degree of freedom in vehicle control.

[0053] (Second Embodiment) A second embodiment will be described with reference to Figure 4. The control system 201 shown in Figure 4 includes an electronic control unit 202. The electronic control unit 202 includes a microcontroller 10 and a control IC 220. The control IC 220 does not have a test voltage application circuit 24. Instead of the test voltage application circuit 24, the control IC 220 has a changeover switch 29.

[0054] As shown in the first embodiment, the predetermined voltage application circuit 23 generates a predetermined voltage V0 to be applied to the AFC terminal Tm. The changeover switch 29 is connected between the output of the predetermined voltage application circuit 23 and the current detection circuit 25 and the AFR terminal Tp, allowing the output of the predetermined voltage application circuit 23 to be switched between supplying to the AFC terminal Tm and the AFR terminal Tp. The other configurations of the control IC 220 are the same as those of the control IC 20, so their description is omitted.

[0055] In the first embodiment, the test voltage application circuit 24 applied the test voltage Vtest to the AFR terminal Tp. In this embodiment, instead, the control unit 21 switches the changeover switch 29 to the AFR terminal Tp side and applies the test voltage Vtest to the AFR terminal Tp through the predetermined voltage application circuit 23. At this time, the predetermined voltage application circuit 23 and the changeover switch 29 realize the function of a "test voltage application unit".

[0056] This allows for the determination of whether the AFR terminal Tp is normal or short-circuited, similar to the first embodiment. According to this embodiment, the circuit for applying a predetermined voltage V0 and the circuit for applying the test voltage Vtest can be combined into one within the control IC 220, thereby reducing costs.

[0057] The electronic control devices 102, 202 and their methods described in this disclosure may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the electronic control devices 102, 202 and their methods described in this disclosure may be implemented by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits.

[0058] Alternatively, the electronic control devices 102, 202 and their methods described herein may be implemented by one or more dedicated computers comprising a combination of a processor and memory programmed to perform one or more functions and a processor comprising one or more hardware logic circuits. The computer program may also be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0059] In other words, the means and / or functions provided by a processor, etc., can be provided by software recorded in a physical memory device and the computer that runs it, by software alone, by hardware alone, or by a combination thereof. For example, some or all of the functions of a processor may be implemented as hardware. Implementation of a certain function as hardware includes implementation using one or more ICs, etc.

[0060] This disclosure is described in accordance with embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and idea of ​​this disclosure. [Explanation of Symbols]

[0061] In the drawing, 10 is a microcontroller, 10a is an AFR ground fault detection unit, 10b is an AFC ground fault detection unit, 102 and 202 are electronic control devices (gas sensor terminal abnormality detection devices), 23 is a predetermined voltage application circuit (test voltage application unit), 24 is a test voltage application circuit (test voltage application unit), and 29 is a changeover switch (test voltage application unit).

Claims

1. A gas sensor terminal abnormality detection device (102, 202) that detects a short-circuit abnormality in the AFR terminal when energizing an oxygen sensor connected between the AFR terminal and the AFC terminal, A predetermined voltage application circuit (23) that applies a predetermined voltage to the AFC terminal to enable the oxygen sensor to operate normally, A test voltage application unit (24; 23, 29) connects to the AFR terminal only when testing the terminal state of the AFR terminal and applies a test voltage as the voltage for detecting the state of the AFR terminal, An AFR ground fault determination unit (10a) determines whether the AFR terminal is normal or ground faulted based on the application of a test voltage by the test voltage application unit, The system includes an AFC ground fault determination unit (10b) that determines whether the AFC terminal is normal or has a ground fault, The test voltage application unit is a gas sensor terminal abnormality detection device that applies the state detection voltage to the AFR terminal only when the AFC terminal is determined to be ground fault.

2. A gas sensor terminal abnormality detection device (102, 202) that detects a short-circuit abnormality in the AFR terminal when energizing an oxygen sensor connected between the AFR terminal and the AFC terminal, A predetermined voltage application circuit (23) that applies a predetermined voltage to the AFC terminal to enable the oxygen sensor to operate normally, A test voltage application unit (24; 23, 29) connects to the AFR terminal only when testing the terminal state of the AFR terminal and applies a test voltage as the voltage for detecting the state of the AFR terminal, The system includes an AFR ground fault determination unit (10a) that determines whether the AFR terminal is normal or ground faulted based on the application of a test voltage by the test voltage application unit, The test voltage application unit is a gas sensor terminal abnormality detection device that sets and applies a test voltage to the AFR terminal as a voltage for detecting the state of the oxygen sensor, with the test voltage set to be below the blackening generation voltage of the oxygen sensor.

3. A gas sensor terminal abnormality detection device (102, 202) that detects a short-circuit abnormality in the AFR terminal when energizing an oxygen sensor connected between the AFR terminal and the AFC terminal, A predetermined voltage application circuit (23) that applies a predetermined voltage to the AFC terminal to enable the oxygen sensor to operate normally, A test voltage application unit (24; 23, 29) connects to the AFR terminal only when testing the terminal state of the AFR terminal and applies a test voltage as the voltage for detecting the state of the AFR terminal, The system includes an AFR ground fault determination unit (10a) that determines whether the AFR terminal is normal or ground faulted based on the application of a test voltage by the test voltage application unit, The test voltage application unit is a gas sensor terminal abnormality detection device configured using a changeover switch (29) that allows the output of the predetermined voltage application circuit to be switched and supplied to the AFR terminal.

4. A gas sensor terminal abnormality detection device (102, 202) that detects a short-circuit abnormality in the AFR terminal when energizing an oxygen sensor connected between the AFR terminal and the AFC terminal, A predetermined voltage application circuit (23) that applies a predetermined voltage to the AFC terminal to enable the oxygen sensor to operate normally, A test voltage application unit (24; 23, 29) connects to the AFR terminal only when testing the terminal state of the AFR terminal and applies a test voltage as the voltage for detecting the state of the AFR terminal, The system includes an AFR ground fault determination unit (10a) that determines whether the AFR terminal is normal or ground faulted based on the application of a test voltage by the test voltage application unit, The system includes a microcontroller (10) that performs fuel feedback control during normal operation. The aforementioned microcontroller is A gas sensor terminal abnormality detection device that, when performing abnormality determination processing for the AFC terminal and the AFR terminal, stores, detects, and determines the abnormality determination values ​​for the AFC terminal and the AFR terminal, and when the AFC terminal is ground faulted and the AFR terminal is normal, performs the same control as during normal operation without performing fail-safe control and outputs a diagnostic signal.

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