JP2006083749A - O2 sensor activity determining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an O<SB>2</SB>sensor activity determining device capable of determining activity at the time of inactivity of an O<SB>2</SB>sensor for outputting higher voltage than a scope of output voltage at the time of activity at proper time. <P>SOLUTION: In this activity device for determining activity at the time of inactivity for the O<SB>2</SB>sensor 35 for outputting higher voltage than the scope of output voltage at the time of activity, amount of increase of warming-up after start after current carrying time of the O<SB>2</SB>sensor 35 to a heater exceeds 20 seconds (S1), that is, while the O<SB>2</SB>sensor is active is stopped and a lean condition is forcedly produced (S3). Consequently, since output of the O<SB>2</SB>sensor 35 becomes 0.45 V or less (S4), activity of the O<SB>2</SB>sensor 35 is determined (S5). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an O ₂ sensor activity determination device that determines the activity of an O ₂ sensor that detects an oxygen concentration in exhaust gas discharged from an internal combustion engine. More particularly, it relates to O ₂ sensor activation determination device can appropriately perform active determination of the O ₂ sensor.

Conventionally, feedback control for controlling the fuel injection amount so that the actual air-fuel ratio becomes the stoichiometric air-fuel ratio based on the output voltage of the O ₂ sensor that detects the oxygen concentration in the exhaust gas discharged from the internal combustion engine (hereinafter, “O ₂ feedback control”) is performed. Here, a normal output voltage is not output unless the O ₂ sensor necessary for performing such O ₂ feedback control is activated. Therefore, it is necessary to shift to O ₂ feedback control after the O ₂ sensor is activated. For this reason, it is necessary to determine the activity of the O ₂ sensor.

Therefore, for example, as described in Patent Document 1, when the output voltage of the O ₂ sensor reaches the activation determination voltage (corresponding to the output voltage at the target air-fuel ratio, for example, set to 0.45 V). In addition, the activity determination of the O ₂ sensor is performed (see sensor output (1) in FIG. 7). Then, after the O ₂ sensor activation determination is performed, the O ₂ feedback control described above is performed (see the broken line shown in sensor output (1) in FIG. 7).

Japanese Patent Laid-Open No. 5-71394 (2nd page, FIG. 9)

However, the activation determination of the O ₂ sensors described above, the output voltage during inactive can be performed the activity determination of the O ₂ sensor is 0V, high voltage (e.g., than the output voltage range at the time of activity during inactive There is a problem that the activation determination of the O ₂ sensor that outputs 1 V or more cannot be performed in a timely manner (see sensor output (2) in FIG. 7). This is because, for example, when the internal combustion engine is cold started, the fuel injection amount is set so that the actual air-fuel ratio becomes rich due to vehicle drivability and the like (see FIG. 7). More specifically, fuel increase with respect to the basic injection amount is performed.

For this reason, the output voltage of the O ₂ sensor is higher than the activation determination voltage (for example, 0.45 V), as indicated by the sensor output (2) in FIG. Therefore, in the O ₂ sensor, the activation determination voltage does not reach the output voltage until the air-fuel ratio becomes lean after the warm-up is completed, and the activation determination of the O ₂ sensor cannot be performed. That is, the activation determination is not performed even though the O ₂ sensor is sufficiently activated.

Further, even after restarting after warming up, the rich state may be maintained for a long time due to an increase in fuel or the like, and the lean state may be delayed after the target timing. Even in such a case, the activity determination of the O ₂ sensor is delayed.

As described above, when the activation determination of the O ₂ sensor is delayed, the start of the O ₂ feedback control is delayed. As a result, there arises a problem that emission and fuel consumption are deteriorated.

Therefore, the present invention has been made to solve the above-described problems, and it is possible to make a timely determination of the activity of an O ₂ sensor that outputs a voltage higher than the output voltage range when activated when inactive. It is an object to provide a _two- sensor activity determination device.

An O ₂ sensor activity determination apparatus according to the present invention, which has been made to solve the above problems, determines the activity of an O ₂ sensor that determines the activity of an O ₂ sensor that detects the oxygen concentration in exhaust gas discharged from an internal combustion engine. In the apparatus, when the O ₂ sensor is inactive, the O ₂ sensor outputs a voltage higher than the output voltage range when activated, and when the output voltage of the O ₂ sensor reaches the output voltage at the target air-fuel ratio, It is characterized by having activity determination means for determining the activity of the O ₂ sensor and lean state transition means for forcibly shifting the combustion condition of the internal combustion engine to a state leaner than the stoichiometric air-fuel ratio.

In this O ₂ sensor activity determination device, the combustion condition of the internal combustion engine can be forcibly shifted to a state leaner than the stoichiometric air-fuel ratio by the lean state transition means. When the lean state is created by the lean state transition means, the output of the O ₂ sensor becomes small (approaches 0V). Thus, the output voltage of the O ₂ sensor output voltage is reached at the target air-fuel ratio, the activity determination of the O ₂ sensor is performed. Therefore, it is possible to make a timely determination of the activity of the O ₂ sensor that outputs a voltage higher than the output voltage range when activated when inactive. That is, the activity determination of the O ₂ sensor by the activity determination means is performed without delay. As a result, since the O ₂ feedback control is started without delay, it is possible to prevent emissions and fuel consumption from deteriorating.

In the O ₂ sensor activity determination device according to the present invention, the O ₂ sensor activity determination device includes energization time detection means for detecting an energization time to the heater provided in the O ₂ sensor, and the lean state transition means is detected by the energization time detection means. It is desirable to forcibly shift the combustion condition of the internal combustion engine to a state leaner than the stoichiometric air-fuel ratio after the energization time for the engine reaches a predetermined time or longer. The predetermined time is an energization time required until the O ₂ sensor is activated, and differs depending on the specification of the O ₂ sensor.

Even if the lean state is created by the lean state transition means immediately after the start of the start, if the O ₂ sensor is not activated, the output voltage of the O ₂ sensor does not reach the output voltage at the target air-fuel ratio. This is because the O ₂ sensor outputs a voltage higher than the output voltage range during activation even when the O ₂ sensor is in a lean state.

Therefore, in this O ₂ sensor activity determination device, after the energization time detected by the energization time detection means exceeds a predetermined time, that is, when the O ₂ sensor is active, the lean state transition means creates a lean state. I have decided. As a result, the output voltage of the O ₂ sensor reliably reaches the output voltage at the target air-fuel ratio, so that the activation determination of the O ₂ sensor can be performed in a timely manner.

  Here, the lean state transition means may shift the combustion condition of the internal combustion engine to a state leaner than the stoichiometric air-fuel ratio by forcibly decreasing the fuel supply amount. Note that decreasing the fuel supply amount includes stopping the fuel supply (cutting the injection amount).

  Alternatively, the lean state transition means may forcibly decrease the fuel supply amount by stopping the fuel increase performed at the time of warming up after the internal combustion engine is started.

The O ₂ sensor activation determination device further embodiment according to the made the present invention to solve the problem, O ₂ for performing the activity determination of the O ₂ sensor for detecting the oxygen concentration in the exhaust gas discharged from an internal combustion engine in the sensor activation determination unit, the O ₂ sensor, and outputs a voltage higher than the output voltage range at the time of activity during inactive, the output voltage of the O ₂ sensor is capable of outputting at the O ₂ sensor is active It is characterized by having an activity judging means for judging the activity of the O ₂ sensor when the voltage becomes lower than the maximum voltage.

In this O ₂ sensor activity determination device, activity determination is performed by the activity determination means when the output voltage of the O ₂ sensor falls below the maximum voltage that can be output during activation. Here, in an O ₂ sensor that outputs a voltage that is higher than the output voltage range during activation when the sensor is inactive, the output voltage decreases as the temperature of the sensor increases. When the sensor temperature reaches the activation temperature (when the sensor is activated), the output voltage becomes equal to or less than the maximum voltage that can be output when the sensor is activated. Therefore, the activation of the O ₂ sensor that outputs a voltage higher than the output voltage range at the time of activation by performing the activation determination when the output voltage of the O ₂ sensor falls below the maximum voltage that can be output at the time of activation. Judgment can be made in a timely manner. That is, the activity determination of the O ₂ sensor by the activity determination means is performed without delay. As a result, since the O ₂ feedback control is started without delay, it is possible to prevent emissions and fuel consumption from deteriorating.

According to the O ₂ sensor activity determination device according to the present invention, as described above, the activity determination of the O ₂ sensor that outputs a voltage higher than the output voltage range at the time of activation when inactive can be performed in a timely manner.

Hereinafter, a most preferred embodiment in which the O ₂ sensor activity determination device of the present invention is embodied will be described in detail with reference to the drawings. In this embodiment, the O ₂ sensor activity determination device of the present invention is applied to an engine system mounted on a motorcycle.

(First embodiment)
First, the first embodiment will be described. The O ₂ sensor activity determination device according to the first implementation is configured to forcibly create a lean air-fuel ratio and to determine the activity of the O ₂ sensor. Therefore, FIG. 1 shows a schematic configuration of an engine system to which the O ₂ sensor activity determination device of the present invention is applied. FIG. 1 is a diagram showing a schematic configuration of an engine system.

  The engine 1 in this system is a single cylinder reciprocating engine having a known structure. The engine 1 drives the piston 5 by exploding and burning fuel and air supplied through the intake passage 2, that is, a combustible mixture, in the combustion chamber 3 and exhausting the exhaust gas after combustion through the exhaust passage 4. The crankshaft 6 is rotated to obtain power.

  The air cleaner 11 provided in the intake passage 2 cleans the air taken into the intake passage 2. The throttle valve 12 provided in the intake passage 2 adjusts the amount of air (intake amount) that flows through the intake passage 2 and is sucked into the combustion chamber 3.

  An injector 14 provided in an intake port communicating with the combustion chamber 3 injects and supplies fuel supplied from a fuel tank 15 via a fuel pump 16 and a fuel pipe 17 to the intake port. The electric fuel pump 16 is built in the fuel tank 15, and pumps up the fuel stored in the fuel tank 15, discharges it to the fuel pipe 17, and pumps it to the injector 14 of the engine 1. A fuel filter 18 provided along with the fuel pump 16 is for filtering the fuel. Similarly, a pressure regulator 19 provided along with the fuel pump 16 adjusts the pressure of the fuel pumped to the injector 14 to be constant.

  When the fuel pump 16 operates, the fuel in the fuel tank 15 is pumped to the injector 14 through the fuel filter 18, the fuel pump 16, the fuel pipe 17, and the like. The fuel pressure-fed to the injector 14 is injected into the intake port with the operation of the injector 14, forms a combustible mixture with the air flowing through the intake passage 2, and is taken into the combustion chamber 3.

  A spark plug 21 provided in the engine 1 corresponding to the combustion chamber 3 ignites the combustible air-fuel mixture taken into the combustion chamber 3. The spark plug 21 performs a spark operation upon receiving a high voltage output from the ignition coil 22. The ignition coil 22 outputs a high voltage for ignition to the spark plug 21 in accordance with a change in the rotation angle of the crankshaft 6. The operation timing (ignition timing) of the spark plug 21 is determined by the output timing of the high voltage output from the ignition coil 22. That is, by controlling the ignition coil 22, the operation of the spark plug 21 is controlled.

  The combustible air-fuel mixture sucked into the combustion chamber 3 explodes and burns by the spark operation of the spark plug 21. The exhaust gas after combustion is discharged from the combustion chamber 3 to the outside through the exhaust port, the exhaust passage 4, the catalytic converter 7, and the like. As the combustible air-fuel mixture burns in the combustion chamber 3, the piston 5 moves up and down and the crankshaft 6 rotates, so that power can be obtained by the engine 1.

  Here, the crankshaft 6 is provided with a flywheel 23. A plurality of protrusions 23 a are provided on the outer periphery of the flywheel 23. On the outer periphery of the flywheel 23, a crank angle sensor 32 made of an electromagnetic pickup is disposed oppositely. The crank angle sensor 32 detects the rotational speed (engine rotational speed) NE of the crankshaft 6 and outputs an electrical signal corresponding to the detected value.

  The flywheel 23 rotates with the rotation of the crankshaft 6 and each time the crank angle sensor 32 detects the passage of each protrusion 23a, one pulse signal is output from the crank angle sensor 32. Yes. In this embodiment, every time the crankshaft 6 makes one revolution, a plurality of pulse signals are continuously output from the crank angle sensor 32.

  The water temperature sensor 33 provided in the engine 1 detects the temperature (cooling water temperature) THW of the cooling water of the engine 1 and outputs an electrical signal corresponding to the detected value. An intake pressure sensor 34 provided in the intake passage 2 detects the pressure (intake pressure) PM in the intake passage 2 and outputs an electrical signal corresponding to the detected value.

The O ₂ sensor 35 provided in the exhaust passage 4 detects the oxygen concentration (output voltage) Ox in the exhaust gas discharged to the exhaust passage 4 and outputs an electric signal corresponding to the detected value. The O ₂ sensor 35 has a built-in heater, and generates a normal output voltage when the temperature of the sensor reaches a predetermined temperature (for example, 300 to 350 ° C.) (when activated). The O ₂ sensor 35 is of a type that outputs a voltage higher than an output voltage range (for example, 0 V to 1 V) when activated when inactive.

  The battery 8 mounted on the motorcycle constitutes a power source for the above-described electric devices and the controller 40 described later. An ignition switch 9 provided in association with the battery 8 is operated to turn on the electric devices and the controller 40 described above.

Various signals output from the crank angle sensor 32, the water temperature sensor 33, the intake pressure sensor 34, and the O ₂ sensor 35 are input to the controller 40. Then, the controller 40 based on the output signal from the O ₂ sensor 35, and performs the activity determination of the O ₂ sensor 35. Further, the controller 40 performs the fuel injection control (including O ₂ feedback control), the ignition control, the fuel pump control, and the like based on the above input signal, the injector 14, the fuel pump 16, the ignition coil 22, and the like. Each is also controlled. This controller 40 corresponds to the activity determination means lean state transition means and energization time detection means of the present invention.

  The controller 40 includes a known configuration, that is, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a backup RAM, an external input circuit, an external output circuit, and the like. The controller 40 constitutes a logical operation circuit formed by connecting a CPU, a ROM, a RAM, a backup RAM, an external input circuit, an external output circuit, and the like through a bus. The ROM stores in advance a predetermined control program related to the various controls. The RAM temporarily stores the calculation result of the CPU. The backup RAM stores previously stored data. The CPU executes the above-described various controls according to a predetermined control program based on the detection values of the various sensors 32 to 35 input via the input circuit.

  Here, the fuel injection control is to control the fuel amount (fuel injection amount) injected from the injector 14 and the injection timing thereof according to the operating state of the engine 1. The ignition control is to control the ignition operation by the ignition plug 21 by controlling the ignition coil 22 according to the rotation of the crankshaft 6.

Next, the activation determination of the O ₂ sensor 35 by the controller 40 in the engine system will be described with reference to FIG. FIG. 2 is a flowchart showing the contents of the O ₂ sensor activity determination process.

First, the controller 40 determines whether or not the energization time for the heater of the O ₂ sensor 35 has become 20 seconds or longer (S1). At this time, when the energization time to the heater of the O ₂ sensor 35 is 20 seconds or more (S2: YES), it is determined whether or not the O ₂ sensor activation determination flag is ON (S3). The O ₂ sensor activation determination flag is set to the OFF state when the engine 1 is started.

When the O ₂ sensor activation determination flag is OFF (S2: NO), the fuel increase at the time of warm-up after the start is stopped (S3). That is, the amount of fuel supplied to the engine 1 is reduced. Thereafter, it is determined whether or not the output voltage of the O ₂ sensor 35 has become 0.45 V (output voltage at the target air-fuel ratio) or less (S4). At this time, if the output voltage of the O ₂ sensor 35 is 0.45 V or less (S4: YES), the O ₂ sensor activation determination flag is turned on (S5), and the stop of the fuel increase is released (S6). ).

On the other hand, if the output voltage of the O ₂ sensor 35 is not 0.45 V or less (S4: NO), this processing routine ends with the stop of the fuel increase during warm-up after the start being continued (S3). ). In this way, the fuel increase is stopped until the output voltage of the O ₂ sensor 35 becomes 0.45 V or less. As a result, the fuel increase at the time of warm-up after starting is stopped to forcibly create a lean state, and the output voltage of the O ₂ sensor 35 is the output voltage at the target air-fuel ratio (0.45 V in the present embodiment). Reaching with certainty. Therefore, it is possible to make a timely determination of the activity of the O ₂ sensor 35 that outputs a voltage higher than the output voltage range when activated when inactive.

In addition, when the energization time to the heater of the O ₂ sensor 35 is not 20 seconds or more (S1: NO), or when the O ₂ sensor activation determination flag is ON (S2: NO), this processing routine ends.

When the O ₂ sensor activation determination flag is turned on, it is determined whether or not to start the O ₂ feedback control. Specifically, it is determined whether or not the cooling water temperature THW detected by the water temperature sensor 33 is 40 ° C. or higher (S7). When the coolant temperature THW is 40 ° C. or higher (S7: YES), O ₂ feedback control is started (S8). As described above, since the activation determination of the O ₂ sensor 35 is performed without delay, the O ₂ feedback control is started without delay. As a result, it is possible to prevent deterioration of emission and fuel consumption.
On the other hand, when the coolant temperature THW is not 40 ° C. or higher (S7: NO), the O ₂ feedback control is not started.

Here, various sensor outputs and the behavior of the air-fuel ratio when performing the above-described determination of the activity of the O ₂ sensor will be described with reference to FIG. FIG. 3 is a time chart showing an example of behaviors of various sensor outputs and air-fuel ratios.

As shown in FIG. 3, after energizing the heater of the O ₂ sensor 35 for 20 seconds or longer (S1: YES), the fuel increase is stopped (S4). As a result, the air-fuel ratio shifts from the rich state to the lean state. For this reason, since the output voltage of the O ₂ sensor 35 is lower than 0.45 V, the activation determination of the O ₂ sensor 35 is performed (S4: YES, S5). At this time, since the cooling water temperature THW detected by the water temperature sensor 33 is 40 ° C. or higher (S7: YES), O ₂ feedback control is started (S8). As a result, the air-fuel ratio becomes substantially the stoichiometric air-fuel ratio (14.7).

As apparent from comparison with the sensor output (2) in FIG. 7, according to the activity determination process of the O ₂ sensor 35 described above, the activity determination of the O ₂ sensor 35 is performed in a timely manner (without delay). I understand that.

Here, the above-described processing of S7 (determination of the water temperature condition) may be set as the increase stop condition. Specifically, the process of S7 may be performed before the process of S3. As a result, the increase stop is executed and the lean state is entered in a state where the condition for shifting to the O ₂ feedback control is satisfied. For this reason, the influence on emission and drivability can be reduced.

When the control of such a modification is performed, as shown in FIG. 4, the energization of the heater of the O ₂ sensor 35 is 20 seconds or more, and the cooling water temperature THW detected by the water temperature sensor 33 is 40 ° C. or more. After that, the fuel increase is stopped. As a result, the air-fuel ratio shifts from the rich state to the lean state. For this reason, the output voltage of the O ₂ sensor 35 falls below 0.45 V, the activation determination of the O ₂ sensor 35 is performed, and the O ₂ feedback control is started. As a result, the air-fuel ratio becomes substantially the stoichiometric air-fuel ratio (14.7). FIG. 4 is a time chart showing an example of behaviors of various sensor outputs and air-fuel ratios when the O ₂ sensor activation determination process in the modification is performed.

Even in the activation determination process of the O ₂ sensor 35 of the above-described modification, the activation determination of the O ₂ sensor 35 is performed in a timely manner (without delay), as is apparent from comparison with the sensor output (2) in FIG. I understand.

As described above in detail, in the O ₂ sensor activation determination device according to the first embodiment, after the energization time to the heater of the O ₂ sensor 35 becomes 20 seconds or longer (S1), that is, O _2. While the sensor is active, the warm-up increase after the start is stopped and a lean state is forcibly created (S3). For this reason, since the output of the O ₂ sensor 35 is 0.45 V or less (S4), the activation determination of the O ₂ sensor 35 is performed (S5). Therefore, the activation determination of the O ₂ sensor 35 that outputs a voltage higher than the output voltage range when activated when inactive can be performed in a timely manner (without delay). As a result, since the O ₂ feedback control is started without delay (S8), it is possible to prevent emissions and fuel consumption from being deteriorated.

(Second Embodiment)
Next, a second embodiment will be described. The liquefied gas fuel supply device according to the second embodiment has the same basic configuration as that of the fuel supply device 10 according to the first embodiment, but differs in the method for determining the activity of the O ₂ sensor. For this reason, in the following description, it demonstrates centering on difference with 1st Embodiment, attaches | subjects the same code | symbol to a drawing about a common point, and abbreviate | omits the description suitably.

Therefore, the activation determination of the O ₂ sensor 35 by the controller 40 in the second embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing the contents of the O ₂ sensor activity determination process.

First, the controller 40 determines whether or not the O ₂ sensor activation determination flag is ON (S21). The O ₂ sensor activation determination flag is set to the OFF state when the engine 1 is started.

If the O ₂ sensor activation determination flag is OFF (S21: NO), it is determined whether or not the output voltage of the O ₂ sensor 35 is below 1V (the maximum voltage that can be output when the sensor is activated) (S22). ). At this time, if the output voltage of the O ₂ sensor 35 falls below 1V (S22: YES), the O ₂ sensor activation determination flag is turned ON (S23). On the other hand, when the output voltage of the O ₂ sensor 35 is 1 V or more (S21: YES), it is determined that the O ₂ sensor 35 is in an inactive state, and this processing routine ends.

Here, when the temperature of the O ₂ sensor 35 reaches the activation temperature (when the sensor is activated), the output voltage falls below the maximum voltage that can be output when the sensor is activated (1 V in the present embodiment). This is because when the O ₂ sensor 35 is activated, its output voltage outputs any value in the output range (0 to 1 V). Thereby, the activation determination of the O ₂ sensor 35 that outputs a voltage higher than the output voltage range at the time of activation can be performed in a timely manner by the process of S22.

If the O ₂ sensor activation determination flag is ON (S21: NO), this processing routine ends.

When the O ₂ sensor activation determination flag is turned on, it is determined whether or not to start the O ₂ feedback control. Specifically, it is determined whether or not the cooling water temperature THW detected by the water temperature sensor 33 is 40 ° C. or higher (S24). When the coolant temperature THW is 40 ° C. or higher (S24: YES), O ₂ feedback control is started (S25). As described above, since the activation determination of the O ₂ sensor 35 is performed without delay, the O ₂ feedback control is started without delay. As a result, it is possible to prevent deterioration of emission and fuel consumption. If the coolant temperature THW is not 40 ° C. or higher (S25: NO), the O ₂ feedback control is not started.

Here, behaviors of various sensor outputs and air-fuel ratios when the above-described determination of the activity of the O ₂ sensor is performed will be described with reference to FIG. FIG. 6 is a time chart showing an example of behaviors of various sensor outputs and air-fuel ratios.

As shown in FIG. 6, after the engine 1 is started, the output voltage of the O ₂ sensor 35 gradually decreases. Since the output voltage of the O ₂ sensor 35 falls below 1 V at time t, the activation determination of the O ₂ sensor 35 is performed (S22: YES, S23). At this time, since the cooling water temperature THW detected by the water temperature sensor 33 is 40 ° C. or higher (S24: YES), O ₂ feedback control is started (S25). As a result, the air-fuel ratio becomes substantially the stoichiometric air-fuel ratio (14.7).

As apparent from comparison with the sensor output (2) in FIG. 7, according to the activity determination process of the O ₂ sensor 35 described above, the activity determination of the O ₂ sensor 35 is performed in a timely manner (without delay). I understand that.

As described above, in the O ₂ sensor activation determination device according to the second embodiment as described in detail, the activation determination is performed when the output voltage of the O ₂ sensor 35 falls below 1V (S22: YES, S23). . Here, the output voltage of the O ₂ sensor 35 decreases when the temperature of the sensor increases, and when the sensor temperature reaches the activation temperature (when the sensor is activated), the output voltage can be output when the sensor is activated. Below the maximum voltage (1V). Therefore, by performing the activation determination when the output voltage of the O ₂ sensor 35 falls below 1V, the activation determination of the O ₂ sensor 35 that outputs a voltage higher than the output voltage range during activation is performed in a timely manner when inactive. be able to. That is, the activity determination of the O ₂ sensor 35 can be performed without delay. As a result, since the O ₂ feedback control is started without delay, it is possible to prevent emissions and fuel consumption from deteriorating.

It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention. For example, the specific numerical values (for example, the activation determination voltage, the energization time, the water temperature, etc.) exemplified in the above-described embodiment are examples, and it goes without saying that the values vary depending on the specifications of the engine 1, the O ₂ sensor 35, and the like. Yes.

Also, a known noise countermeasure may be incorporated so as not to make a false determination when the output voltage of the O ₂ sensor 35 falls below the activation determination voltage (0.45 V and 1 V in the above embodiment) due to the influence of noise or the like. it can.

It is a figure which shows schematic structure of an engine system. It is a flowchart showing the contents of the active determination processing of the O ₂ sensor in the first embodiment. It is a time chart showing an example of the behavior of the various sensor outputs and the air-fuel ratio when the O ₂ sensor activation determination process in the first embodiment is performed. O ₂ sensor activation determining process is a time chart showing an example of the behavior of the various sensor outputs and the air-fuel ratio when made according to a modification of the first embodiment. It is a flowchart which shows the content of the active determination process of the O2 sensor in _2nd Embodiment. It is a time chart which shows an example of the behavior of various sensor outputs at the time of the O2 sensor activity determination processing in a _2nd embodiment being performed, and an air fuel ratio. Is a time chart showing an example of the behavior of the various sensor outputs and the air-fuel ratio when the conventional O ₂ sensor activation determining process is performed.

Explanation of symbols

1 Engine 14 Injector 16 Fuel pump 35 O ₂ sensor 40 Controller

Claims (5)

In O ₂ sensor activation determination unit for performing the activity determination of the O ₂ sensor for detecting the oxygen concentration in the exhaust gas discharged from an internal combustion engine,
The O ₂ sensor outputs a voltage higher than the output voltage range when activated when inactive.
And activation determining means for performing the activity determination of the O ₂ sensor when the output voltage of the O ₂ sensor has reached the output voltage at the target air-fuel ratio,
Lean state transition means for forcibly shifting the combustion condition of the internal combustion engine to a state leaner than the theoretical air-fuel ratio;
An O ₂ sensor activity determination device comprising: In the O ₂ sensor activity determination device according to claim 1,
Energization time detecting means for detecting the energization time to the heater provided in the O ₂ sensor;
The lean state transition means forcibly shifts the combustion condition of the internal combustion engine to a state leaner than the stoichiometric air-fuel ratio after the energization time detected by the energization time detection means exceeds a predetermined time. O ₂ sensor activity determination device. In the O ₂ sensor activity determination device according to claim 1 or 2,
The lean state transition means, by forcibly reducing the fuel supply amount, O ₂ sensor activation determination apparatus characterized by shifting the combustion condition of the internal combustion engine to a lean state than the stoichiometric air-fuel ratio. In the O ₂ sensor activity determination device according to claim 3,
The lean state transition means forcibly decreases the fuel supply amount by stopping the fuel increase performed at the time of warm-up after the internal combustion engine is started, and is an O ₂ sensor activity determination device. In O ₂ sensor activation determination unit for performing the activity determination of the O ₂ sensor for detecting the oxygen concentration in the exhaust gas discharged from an internal combustion engine,
The O ₂ sensor outputs a voltage higher than the output voltage range when activated when inactive.
O ₂ sensor activation determination apparatus characterized by having an activity decision means for performing the activity determination of the O ₂ sensor when the output voltage of the O ₂ sensor is the O ₂ sensor is below the maximum voltage that can be output when active .

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