JP6559002B2 - Lambda sensor failure diagnosis method and vehicle motion control device - Google Patents

Description

  The present invention relates to a method for diagnosing a lambda sensor used for air-fuel ratio control of a vehicle, and more particularly to a method for improving reliability.

In a motor vehicle, improvement of the combustion efficiency of fuel in the engine is always an important technical problem.For this reason, for example, a method for maintaining a good combustion state while grasping the combustion state using a sensor such as a lambda sensor, It is well known that various devices and the like have been proposed and put into practical use.
Lambda sensors used for grasping the combustion state that has a large influence on vehicle operation are provided in the sensor because accurate detection operation is guaranteed in a state where the temperature of the sensor itself is maintained within a certain temperature range. Temperature control of the heater is important, and various methods, devices, etc. relating to temperature control have been proposed and put into practical use (see, for example, Patent Document 1).

  By the way, the lambda sensor is often provided in a state where it is almost exposed to the outside air. When the vehicle is used in a cryogenic environment, the heat generated by the heater is taken away by the outside air or the cold air. In some cases, the element temperature of the lambda sensor does not increase slowly, but rather a temperature decrease occurs, so-called element cooling.

  On the other hand, in a vehicle equipped with a lambda sensor, from the viewpoint of the importance of the lambda sensor, etc., it is configured such that a diagnosis process for whether or not it is in a normal state is performed. In general, a diagnosis is made as to whether or not the heater temperature is normal depending on whether or not the heater temperature is maintained above a predetermined temperature for a predetermined time.

However, in such conventional fault diagnosis, no consideration is given to the environmental conditions when the vehicle is used. Therefore, even if the element temperature of the lambda sensor rises only slowly due to the previous element cooling, a diagnosis is made as a fault. In some cases, processing such as alarm generation may be performed, and it does not necessarily provide a sufficiently reliable failure diagnosis.
Therefore, as a measure for coping with such a problem, for example, a temperature sensor that directly detects the outside air temperature is provided, and based on the detected temperature, it is determined whether or not element cooling has occurred. It is conceivable to adopt a configuration that avoids misdiagnosis.

JP 2007-24538 A (page 5-17, FIGS. 1 to 13)

  However, as described above, the configuration of newly providing a dedicated temperature sensor for detecting the outside air temperature is simple as a means for solving the problem, but in a vehicle having many restrictions on the installation space of parts, The addition of new components is not realistic. Even if such a configuration can be adopted, the number of components is not limited to an increase. In the manufacturing process, new sensors such as attachment work and inspection work are added. There is a problem that work is required, resulting in an increase in device price.

  The present invention has been made in view of the above circumstances, and a lambda sensor failure diagnosis method capable of more accurately diagnosing the presence or absence of a lambda sensor failure even in an extremely low temperature environment without adding new parts. And the operation control apparatus for vehicles is provided.

In order to achieve the above object of the present invention, a lambda sensor failure diagnosis method according to the present invention includes:
In the lambda sensor failure diagnosis method of diagnosing a failure of the lambda sensor when the element temperature of the lambda sensor does not exceed a predetermined reference temperature after the start of the lambda sensor,
When it is determined whether or not the outside air temperature is in a predetermined cryogenic state based on an index temperature that can indirectly estimate the outside air temperature, and the outside air temperature is determined to be in a predetermined cryogenic state based on the index temperature Further, assuming that the increase in the element temperature of the lambda sensor is suppressed due to the extremely low temperature state, and the lambda sensor is in the element cold state, the diagnosis of the failure of the lambda sensor due to the element temperature of the lambda sensor is temporarily performed. It is configured to be temporarily suspended.
In order to achieve the above object of the present invention, a vehicle operation control device according to the present invention includes:
An electronic control unit configured to be able to execute operation control of a diesel engine, and a lambda sensor that detects an oxygen concentration in exhaust gas, and an output signal of the lambda sensor is output from the engine by the electronic control unit. A vehicle motion control device configured to be subjected to motion control processing,
The electronic control unit is
When the element temperature of the lambda sensor after the start of the lambda sensor does not exceed a predetermined reference temperature, while diagnosing a failure of the lambda sensor,
When it is determined whether or not the outside air temperature is in a predetermined cryogenic state based on an index temperature that can indirectly estimate the outside air temperature, and the outside air temperature is determined to be in a predetermined cryogenic state based on the index temperature Further, assuming that the increase in the element temperature of the lambda sensor is suppressed due to the extremely low temperature state, and the lambda sensor is in the element cold state, the diagnosis of the failure of the lambda sensor due to the element temperature of the lambda sensor is temporarily performed. It is configured to be temporarily suspended.

  According to the present invention, it is determined whether the outside air is in a cryogenic state using the output value or simulation temperature of an existing sensor as an index temperature, and is determined to be in a cryogenic state, When it is determined that the element temperature of the lambda sensor does not reach the original temperature even though the lambda sensor itself is normal, the conventional diagnosing whether the lambda sensor is faulty or not only by the element temperature of the lambda sensor. Since the process is forcibly put on hold, it is possible to reliably reduce and prevent the occurrence of erroneous fault diagnosis results due to relying solely on the element temperature of the lambda sensor, and to perform more reliable fault diagnosis This has the effect of reducing the unnecessary replacement of the lambda sensor and the electronic control unit.

It is a block diagram which shows the structural example of the common rail type | mold fuel-injection control apparatus as a vehicle operation control apparatus in embodiment of this invention. It is a block diagram which shows the structural example of the exhaust-gas recirculation apparatus applied to the engine in embodiment of this invention. It is a subroutine flowchart which shows the procedure of the first half part of the lambda sensor failure diagnosis process in embodiment of this invention. It is a subroutine flowchart which shows the procedure of the second half part of the lambda sensor failure diagnostic process in embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, a configuration example of a common rail fuel injection control device as a vehicle operation control device to which the lambda sensor failure diagnosis method according to the embodiment of the present invention is applied will be described with reference to FIG.
The common rail fuel injection control device according to the embodiment of the present invention includes a high pressure pump device 50 that pumps high pressure fuel, a common rail 1 that stores high pressure fuel pumped by the high pressure pump device 50, and a common rail 1 that is supplied from the common rail 1. A plurality of injectors (fuel injection valves) 2-1 to 2-n that inject fuel into a cylinder of a diesel engine (hereinafter referred to as “engine”) 3 as an internal combustion engine, fuel injection control processing, and the like An electronic control unit (indicated as “ECU” in FIG. 1) 4 that executes a lambda sensor failure diagnosis process or the like is configured as a main component.
Such a configuration itself is the same as the basic configuration of this type of common rail fuel injection control device that has been well known.

The high-pressure pump device 50 has a known and well-known configuration with the supply pump 5, the metering valve 6, and the high-pressure pump 7 as main components.
In this configuration, the fuel in the fuel tank 9 is pumped up by the supply pump 5 and supplied to the high-pressure pump 7 through the metering valve 6. As the metering valve 6, an electromagnetic proportional control valve is used, and the amount of energization is controlled by the electronic control unit 4, so that the flow rate of fuel supplied to the high-pressure pump 7, in other words, the discharge of the high-pressure pump 7. The amount is to be adjusted.

A return valve 8 is provided between the output side of the supply pump 5 and the fuel tank 9 so that surplus fuel on the output side of the supply pump 5 can be returned to the fuel tank 9. .
The supply pump 5 may be provided separately from the high-pressure pump device 50 on the upstream side of the high-pressure pump device 50 or may be provided in the fuel tank 9.
The injectors 2-1 to 2-n are provided for each cylinder of the engine 3, are supplied with high-pressure fuel from the common rail 1, and perform fuel injection by injection control by the electronic control unit 4.

The electronic control unit 4 has, for example, a microcomputer (not shown) having a known and well-known configuration, a storage element (not shown) such as a RAM and a ROM, and injectors 2-1 to 2-1. A circuit (not shown) for energizing and driving 2-n and a circuit (not shown) for energizing and driving the metering valve 6 and the like are configured as main components.
In addition to the detection signal of the pressure sensor 11 that detects the pressure of the common rail 1 being input to the electronic control unit 4, various detection signals such as the engine speed, the accelerator opening, the outside air temperature, and the atmospheric pressure are received by the engine 3. These are input for use in the operation control, fuel injection control, and lambda sensor failure diagnosis processing in the embodiment of the present invention.

Further, in the embodiment of the present invention, an exhaust gas recirculation device 101 is provided as shown in FIG. 2 in order to reduce emissions.
Hereinafter, the configuration of the exhaust gas recirculation device 101 will be described with reference to FIG.
An intake pipe 12 for taking in air necessary for fuel combustion is connected to the intake manifold 14a of the engine 3, and an exhaust pipe 13 for exhausting exhaust gas is connected to the exhaust manifold 14b. .

  A communication passage 15 that communicates the intake pipe 12 and the exhaust pipe 13 is provided at an appropriate position of the intake pipe 12 and the exhaust pipe 13. An EGR cooler 17 for cooling the gas and a communication state of the communication passage 15, in other words, an EGR valve 16 for adjusting the recirculation amount of the exhaust gas are sequentially arranged.

Further, a known and well-known configuration in which the variable turbine 19 provided on the downstream side of the communication passage 15 in the exhaust pipe 13 and the compressor 20 provided on the upstream side of the communication passage 15 in the intake pipe 12 are main components. A variable turbo 18 is provided. Then, the compressor 20 is rotated by the rotational force obtained by the variable turbine 19, and the compressed air is sent to the intake manifold 14a as intake air.
Further, the intake pipe 12 is provided with an intercooler 21 for cooling the intake air at an appropriate position between the communication passage 15 and the variable turbo 18 described above.
An intake throttle valve 22 for adjusting the amount of intake air is provided between the intercooler 21 and the communication passage 15.

A filter 23 for cleaning the intake air is provided on the upstream side of the intake pipe 12, and an air mass sensor 24 for detecting the amount of intake air flowing in through the filter 23 is provided on the downstream side thereof. Is provided.
Further, in the intake pipe 12, an intake air temperature sensor 25 for detecting the temperature of intake air of the engine 1 is provided between the intercooler 21 and the intake throttle valve 22, and on the downstream side of the intake throttle valve 22. Is provided with an intake pressure sensor 26 for detecting the intake pressure of the intake manifold 14a.

On the other hand, in the exhaust pipe 13, an exhaust brake 28 (or an exhaust flap) that blocks the flow of exhaust gas is provided on the downstream side of the variable turbine 19, and a lambda sensor 27 is further provided on the downstream side of the exhaust brake 28.
The detection signals from the air mass sensor 24, the intake air temperature sensor 25, the intake pressure sensor 26, and the lambda sensor 27 are input to the electronic control unit 4 to perform fuel injection control processing and lambda in the embodiments of the present invention to be described later. It is used for sensor failure diagnosis processing and the like.

Next, the lambda sensor failure diagnosis process in the embodiment of the present invention executed by the electronic control unit 4 will be described with reference to FIGS.
When processing by the electronic control unit 4 is started, first, a heater (not shown) provided in the lambda sensor 27 is energized, the element temperature of the lambda sensor is equal to or lower than the first reference temperature, and It is determined whether or not the voltage (battery voltage) of the vehicle battery (not shown) is lower than the reference battery voltage (see step S102 in FIG. 3).
When it is determined in step S102 that the element temperature of the lambda sensor is equal to or lower than the first reference temperature and the voltage (battery voltage) of the vehicle battery (not shown) is lower than the reference battery voltage (in the case of YES) ) Does not match the diagnosis condition, and the series of processing is terminated as the diagnosis is impossible (see step S128 in FIG. 4), and the process once returns to the main routine (not shown).

  That is, in a state where the element temperature of the lambda sensor is equal to or lower than the first reference temperature and the battery voltage is lower than the reference battery voltage, the element temperature of the lambda sensor reaches a temperature at which normal operation of the lambda sensor 27 can be ensured. In addition, when the battery voltage is lower than the reference battery voltage, the voltage is not sufficient to increase the element temperature of the lambda sensor to a desired temperature, and the normal operation of the lambda sensor 27 cannot be ensured. Therefore, failure diagnosis based on the following processing is not possible.

Note that the lambda sensor 27 is provided with a temperature measuring internal resistor (not shown) for measuring the element temperature of the lambda sensor, and the element temperature of the lambda sensor determined in step S102 is for temperature measurement. It is obtained using an internal resistor (not shown).
That is, there is a certain correlation between the resistance value of the temperature measuring internal resistor (not shown) and the element temperature of the lambda sensor, and this correlation is one of the electrical characteristics of the lambda sensor 27. Therefore, the element temperature of the lambda sensor is calculated and calculated by the electronic control unit 4 in the electronic control unit 4 based on the correlation. Yes.

On the other hand, if it is determined in step S102 that the element temperature of the lambda sensor is equal to or lower than the first reference temperature and the battery voltage is not lower than the reference battery voltage (NO), the lambda sensor Whether or not 27 itself is normal is determined (see step S104 in FIG. 3).
That is, whether or not the lambda sensor 27 itself is normal is determined, for example, by determining whether or not a disconnection or a short circuit has occurred, whether or not the output voltage of the lambda sensor 27 itself is outside a predetermined voltage range, and the like. . Such processing for determining whether the lambda sensor 27 itself is normal has been performed conventionally, and in the embodiment of the present invention, it is separately executed in the electronic control unit 4 as in the prior art. It is assumed that Therefore, in this step S104, it is not necessary to determine again whether or not there is a disconnection or a short circuit as described above, and it is determined whether or not the lambda sensor 27 itself obtained by performing separately as described above is normal. Use the results.

  Therefore, if it is determined in step S104 that the lambda sensor 27 itself is normal (in the case of YES), the process proceeds to step S106 described below, while if it is determined that the lambda sensor 27 itself is not normal ( In the case of NO), since it is not in a state suitable for executing the subsequent processing, the process returns to the main routine (not shown) through step S128.

Next, in step S106, it is determined whether or not an internal resistance for temperature measurement (not shown) provided in the lambda sensor 27 for measuring the element temperature of the lambda sensor of the lambda sensor 27 is normal.
Whether or not the internal resistance for temperature measurement (not shown) is normal is determined by, for example, determining the internal resistance for temperature measurement in which a resistance value calculated based on a current obtained by energization and a voltage at the time of energization is obtained It can be determined by whether or not the resistance value is within a range of resistance values generated in the operating state of the resistor.

  If it is determined in step S106 that the internal resistance for temperature measurement (not shown) is normal (in the case of YES), the process proceeds to step S108 described below, while the internal resistance for temperature measurement (see FIG. If it is determined that it is not normal (in the case of NO), the process returns to the main routine (not shown) once through step S128.

In step S108, immediately after the vehicle is started, in other words, immediately after the energization of the heater (not shown) of the lambda sensor 27 is started, the heater duty (Heater Duty) exceeds the reference duty. It is also determined whether the element temperature of the lambda sensor exceeds the second reference temperature immediately after the vehicle is started.
If it is determined that the heater duty does not exceed the reference duty and it is determined that the element temperature of the lambda sensor does not exceed the second reference temperature (in the case of NO), step S128 is performed. After that, the process once returns to the main routine (not shown).

On the other hand, if the heater duty exceeds the reference duty, or the element temperature of the lambda sensor exceeds the second reference temperature (in the case of YES), the process proceeds to step S110.
Here, energization of a heater (not shown) of the lambda sensor 27 is normally PWM-controlled, and the heater duty is a repetition period of energization control of a heater (not shown) by the PWM control ( The ratio of the energization time to the

Immediately after the vehicle is started, in other words, immediately after energization of a heater (not shown) of the lambda sensor 27 is started, the lambda sensor 27 may not be sufficiently warmed. On the other hand, since the reference duty is substantially the heater duty in the maximum energized state, the energization is maximized in the state where the lambda sensor 27 is not sufficiently warmed or is almost close to the outside air temperature, particularly in a cryogenic weather environment. When the element temperature of the lambda sensor is suddenly raised as a state, the lambda sensor 27 is damaged when the moisture in the lambda sensor 27 is suddenly warmed and evaporated (taken away) by the heat of a heater (not shown). May be incurred.
Therefore, in step S108, immediately after the vehicle is started, preheating for gradually evaporating the water inside the lambda sensor 27 by suppressing the amount of current supplied to the heater (not shown) so that the lambda sensor 27 is not damaged. Therefore, until the heater duty (Heater Duty) exceeds the reference duty, it is not ready to perform subsequent failure diagnosis processing. Suspend diagnostic processing temporarily.

In addition, when the element temperature of the lambda sensor exceeds the second reference temperature (first reference temperature> second reference temperature) immediately after the start of the vehicle, the lambda sensor 27 is immediately before the start. The heater (not shown) is energized, and then the ignition switch (not shown) of the vehicle is turned off to stop the operation, and then restarted. This means that the element temperature of the sensor is in a relatively high state.
In such a state, it is determined that the lambda sensor 27 is operating normally, and the process proceeds to step S110.

In step S110, it is determined whether or not the vehicle is in an overrun state, that is, whether or not the accelerator is depressed and is in a non-injection state. If it is determined that the vehicle is in an overrun state (in the case of YES) ), Assuming that the state is not suitable for executing the failure diagnosis, the process returns to the main routine (not shown) through step S128.
When the vehicle is in an overrun state, the exhaust air is blocked by the exhaust brake 28 and the exhaust gas does not hit the lambda sensor 27. Therefore, the oxygen amount cannot be measured correctly, and this fault diagnosis is executed. Therefore, the series of processes is terminated as described above.

On the other hand, when it is determined in step S110 that the overrun state is not established (in the case of NO), it is determined whether or not the index temperature is abnormal (see step S112 in FIG. 4).
Here, the index temperature is an index for determining whether the element temperature of the lambda sensor of the lambda sensor 27 is normal, and is a temperature at which the outside air temperature can be estimated indirectly. It is preferable to select a temperature sensor mounted on the vehicle, for example, a temperature detected by a sensor such as an intake air temperature sensor (not shown), and use it as an index temperature.

Further, a simulation temperature model may be arbitrarily selected, and the simulation temperature calculated and calculated in the electronic control unit 4 may be used as the index temperature. As such a simulation temperature, for example, the wall surface temperature of the exhaust pipe is suitable. The wall surface temperature of the exhaust pipe can be calculated by a predetermined arithmetic expression based on the heat capacity of the exhaust pipe, the exhaust flow rate, the exhaust temperature, and the like, and is a well-known technique.
Since the index temperature is arbitrarily selected as desired as described above, the criterion for determining whether the temperature is abnormal is set according to the selected sensor or the temperature model. And is not limited to a specific value.

  Therefore, when it is determined that the index temperature is abnormal (in the case of YES), the process proceeds to the process of step S114, assuming that the index temperature is not suitable for executing the processes after step S122. When it is determined that the temperature is not abnormal (in the case of NO), the process proceeds to step S122.

In step S122, it is determined whether or not the index temperature is lower than the determination temperature. If it is determined that the index temperature is lower than the determination temperature (in the case of YES), the process proceeds to step S124 while the determination temperature is set. If it is determined that it is not lower (NO), the process proceeds to step S114.
Here, the determination temperature is a temperature for determining whether or not the index temperature is a temperature corresponding to the extremely low temperature state of the outside air temperature.
In the embodiment of the present invention, it is assumed that the outside air temperature is −25 ° C. or lower as an extremely low temperature state, and the determination temperature is determined to be a temperature corresponding to the outside air temperature −25 ° C. or lower. Temperature. The determination temperature is different depending on what is used as the index temperature, and is not limited to a specific temperature.

  Therefore, when it is determined in step S122 that the index temperature is lower than the determination temperature (in the case of YES), that is, in the embodiment of the present invention, the index temperature corresponds to -25 degrees or less of the outside air temperature. If it is determined that the temperature is to be determined (in the case of YES), the process proceeds to step S124 described below, while the index temperature is determined not to be a temperature corresponding to -25 degrees or less of the outside air temperature ( In the case of NO), the process proceeds to step S114 described later.

In step S124, the failure diagnosis of the lambda sensor 27 is temporarily put on hold. Here, the temporarily suspended failure diagnosis can be executed independently of the lambda sensor failure diagnosis processing in the embodiment of the present invention shown in FIGS. 3 and 4, for example, processing such as disconnection detection Except for the above, other failure diagnosis processing on the premise that the lambda sensor failure diagnosis processing in the embodiment of the present invention shown in FIGS. 3 and 4 is executed is included.
In a state where the index temperature is determined to be a temperature corresponding to −25 ° C. or less of the outside air temperature, even if the heater of the lambda sensor 27 is energized, the outside temperature is larger than the increase in the element temperature of the lambda sensor. This is a so-called “element cooling” state in which the decrease in the element temperature of the lambda sensor due to heat removal is large. For this reason, the apparent element temperature of the lambda sensor 27 does not reach a temperature commensurate with energization and is a low temperature. Therefore, when failure diagnosis is performed in this state, the lambda sensor 27 itself is not a failure. There is a possibility that it is erroneously determined as a failure. In step S124, execution of failure diagnosis is temporarily suspended to avoid such erroneous determination.

Next, the heater duty is forcibly reduced, a series of processes are terminated, and the process returns to the main routine (not shown).
Here, the lowering of the heater duty means that the energization amount of the heater (not shown) is reduced. In this way, the lowering of the heater duty, that is, the forced reduction of the heater duty is because the outside air temperature is −25. In an environment of less than 1 degree, if the heater is energized with a large energization amount as usual, the energization time at the assumed maximum output will be prolonged, resulting in a significant decrease in product life, and to avoid it as much as possible. is there.
Further, in extremely low temperature conditions, moisture may adhere to the inside of the lambda sensor 27 or condensation may occur, and the lambda sensor 27 may be damaged. Therefore, energization to the heater (not shown) is not completely stopped. The heater (not shown) is energized to such an extent that moisture does not evaporate rapidly.
It should be noted that the degree to which the heater duty is reduced is preferably determined based on test results and simulation results in consideration of individual specific electrical specifications of the lambda sensor 27 and the like.

  On the other hand, in step S114, the index temperature is abnormal and unreliable (see step S112 in FIG. 4), or the element is not cooled (see step S122 in FIG. 4). It is determined whether or not the element temperature of the lambda sensor is lower than the third reference temperature and the state continues for a predetermined determination time.

  In step S114, if it is determined that the element temperature of the lambda sensor is lower than the third reference temperature and the state is in a continuous state for a predetermined determination time or more (in the case of YES), the element of the lambda sensor is determined. It is assumed that the temperature does not reach the original temperature, that is, the state of “element temperature error of lambda sensor” (see step S116 in FIG. 4), and energization control of the lambda sensor 27 is forcibly stopped, Alarm processing is performed (see step S118 in FIG. 4). Thereafter, a series of processing is ended, and the process once returns to a main routine (not shown).

Here, the predetermined determination time should be appropriately selected based on the test result and the simulation result in consideration of the specific specification of the lambda sensor 27, and is not limited to a specific value. .
The alarm process is preferably performed by, for example, turning on a so-called MIL (Multi function Indicator Lamp) lamp, generating an alarm sound by a ringing element, or the like.

  On the other hand, if it is determined in step S114 that the state where the element temperature of the lambda sensor is lower than the third reference temperature has not been continued for a predetermined determination time (in the case of NO), the heater ( (Not shown) is not abnormal, a series of processing is terminated, and the process once returns to the main routine (not shown) (see step S120 in FIG. 4).

  The present invention can be applied to a vehicle in which a reliable diagnosis of a lambda sensor in a cryogenic environment is desired.

DESCRIPTION OF SYMBOLS 1 ... Common rail 3 ... Engine 4 ... Electronic control unit 27 ... Lambda sensor

Claims (8)

In the lambda sensor failure diagnosis method for diagnosing a failure of the lambda sensor when the element temperature of the lambda sensor after the start of the lambda sensor for detecting the oxygen concentration in the exhaust gas does not exceed a predetermined reference temperature,
It is determined whether or not the outside air temperature is lower than a predetermined determination temperature based on an index temperature that can indirectly estimate the outside air temperature. When it is determined that the outside air temperature is lower than the determination temperature , the lambda sensor as in the state of the element cold lambda sensor rise of the element temperature Ru is suppressed of the lambda sensor by that decrease the element temperature of the lambda probe is due to the heat is taken away by the outside air even if the power supply control to the heater A method for diagnosing a lambda sensor failure, which temporarily suspends the diagnosis of the presence or absence of a lambda sensor failure based on the element temperature of the lambda sensor.   The lambda sensor failure diagnosis method according to claim 1, wherein the index temperature is a temperature of exhaust gas. The lambda sensor fault diagnosis method according to claim 1, wherein the index temperature is a wall surface temperature of an exhaust pipe through which the exhaust gas passes .   While the diagnosis of the failure of the lambda sensor due to the element temperature of the lambda sensor is temporarily suspended, the energization amount of the heater of the lambda sensor is forcibly given priority over the energization control of the heater of the lambda sensor. 4. The lambda sensor failure diagnosis method according to claim 1, wherein the lambda sensor is reduced to protect the lambda sensor. An electronic control unit configured to be able to execute operation control of a diesel engine and a lambda sensor for detecting oxygen concentration in exhaust gas, and an output signal of the lambda sensor is an operation of the engine by the electronic control unit. A vehicle motion control device configured to be subjected to a control process,
The electronic control unit is
When the element temperature of the lambda sensor after the start of the lambda sensor does not exceed a predetermined reference temperature, while diagnosing a failure of the lambda sensor,
It is determined whether or not the outside air temperature is lower than a predetermined determination temperature based on an index temperature that can indirectly estimate the outside air temperature. When it is determined that the outside air temperature is lower than the determination temperature , the lambda sensor as in the state of the element cold lambda sensor rise of the element temperature Ru is suppressed of the lambda sensor by that decrease the element temperature of the lambda probe is due to the heat is taken away by the outside air even if the power supply control to the heater The vehicle operation control device is configured to temporarily hold the diagnosis of the presence or absence of a failure of the lambda sensor based on the element temperature of the lambda sensor.   6. The vehicle operation control device according to claim 5, wherein the index temperature is a temperature of exhaust gas. 6. The vehicle operation control device according to claim 5, wherein the index temperature is a wall surface temperature of an exhaust pipe through which the exhaust gas passes . The electronic control unit is
While the diagnosis of the failure of the lambda sensor due to the element temperature of the lambda sensor is temporarily suspended, the energization amount of the heater of the lambda sensor is forcibly given priority over the energization control of the heater of the lambda sensor. The vehicular operation control device according to any one of claims 5 to 7, wherein the vehicular operation control device is configured to be lowered and capable of protecting the lambda sensor in the cold state of the element .

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