JP3975512B2 - Engine abnormality diagnosis device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine abnormality diagnosis apparatus.
[0002]
[Prior art]
In a conventional fuel injection type engine in the intake port (in an engine in which fuel is injected and supplied into the intake port, combustion is performed at a stoichiometric air fuel ratio (stoichi, λ≈14.7). Since the sensitivity of engine output and drivability is relatively small for flammability, a small amount of fuel has a relatively small effect on flammability and drivability (see FIG. 7).
[0003]
[Problems to be solved by the invention]
However, for example, in the case where combustion is performed under a lean air-fuel ratio (λ = 30 to 40) as in a so-called direct in-cylinder fuel injection type engine in which fuel is directly injected into the in-cylinder (combustion chamber). Since the sensitivity of engine output and drivability is large with respect to the fuel amount, even if a small amount of fuel is abnormal, there is a possibility that the influence on the combustibility and drivability will increase (see Fig. 7). ). In addition, there is a similar concern when the lean operation is performed even in the fuel injection type engine in the intake port.
[0004]
The present invention has been made in view of such circumstances, and in order to prevent deterioration of flammability and operability when the engine fuel supply system is abnormal, the engine is not limited to during stoichiometric operation but also during lean operation. An object of the present invention is to provide an engine abnormality diagnosis device capable of diagnosing abnormality of a fuel supply system with high accuracy.
[0005]
[Means for Solving the Problems]
  For this reason, the invention according to claim 1
  engineDuring the expansion stroke, the amount of change in target torque per predetermined time is compared with the amount of change in actual generated torque.Diagnose engine abnormality.
  With this configuration,Target torque andSince engine abnormality is diagnosed based on actual engine generated torque, engine abnormality can be diagnosed without being based on, for example, an air-fuel ratio feedback correction coefficient or learning value set by air-fuel ratio feedback control. It is possible to diagnose an abnormality of the engine (fuel system) with a simple configuration regardless of whether the engine is lean or lean. Therefore, it is possible to prevent adverse effects on flammability and operability due to engine abnormalities.Become.
  In addition, since the diagnosis is performed by comparing the amount of change of the target torque and the generated torque per predetermined time, abnormality diagnosis based on the torque can be performed with high accuracy regardless of the environmental conditions. Accuracy can be improved.
[0006]
  Invention of Claim 2Then, as shown in FIG.
  Target torque calculating means for calculating the target torque of the engine;
  Control means for controlling the engine so as to achieve the target torque calculated by the target torque calculating means;
  Generated torque detection means for detecting the actual generated torque of the engine;
  During the expansion process of the engine,Calculated by the target torque calculating meansChange amount of target torqueAnd the actual torque detected by the generated torque detectorThe amount of change in generated torque,Abnormality diagnosis means for performing engine abnormality diagnosis based on
Constructed including.
[0007]
  According to the invention of claim 2, the effect described in claim 1 is obtained.
  Claim 3In the invention described in
  The engine is an engine that directly injects fuel into the cylinder.
[0008]
With such a configuration, in a so-called in-cylinder direct fuel injection type internal combustion engine that directly injects fuel into the cylinder (inside the cylinder), the fuel is supplied directly into the cylinder, so the fuel transportation delay is small. In addition to being sensitive to the abnormality in the amount of fuel, the relationship between the air-fuel ratio (fuel supply amount) and the generated torque is linear during lean operation. Although there is a possibility that the influence on sex will become large, it becomes possible to prevent such a concern in advance.
[0009]
  Claim 4In the invention described in
  While operating the engine in the stratified combustion mode, the engine abnormality diagnosis is performed based on the actual generated torque of the engine.
  With this configuration, while the engine is operating in a stratified combustion mode (a combustion mode in which fuel is supplied into the cylinder during the intake stroke), the above-mentioned concern is further increased, but such a concern should be avoided in advance. Etc. are possible.
[0010]
  Claim 5In the invention described in the above, the engine abnormality diagnosis based on the actual generated torque of the engine is performed while the engine is operating at a lean air-fuel ratio.
  With this configuration, when the engine is operated at a lean air-fuel ratio (lean operation), regardless of whether it is a fuel injection engine in the intake port or a direct fuel injection engine in the cylinder, it is sensitive to an abnormality in the fuel supply amount. Although the generated torque changes, the engine abnormality cannot be diagnosed based on the air-fuel ratio feedback correction value or the learned value as in the stoichiometric operation, but during the transition to the lean operation or the lean operation Even when an abnormality occurs during operation, this can be diagnosed with high accuracy, so that, for example, it is possible to prevent an adverse effect on lean operation.
[0012]
  Claim 6In the invention described in the above, it is configured to include air-fuel ratio feedback control means for correcting the fuel supply amount via the air-fuel ratio feedback correction value so as to control the actual air-fuel ratio in the vicinity of the theoretical air-fuel ratio, When the engine abnormality diagnosis based on the generated torque is diagnosed as having an abnormality in the engine, the engine abnormality diagnosis is performed based on the air-fuel ratio feedback correction value set by the air-fuel ratio feedback control means, and the air-fuel ratio When the engine is diagnosed as having an abnormality based on the engine abnormality diagnosis based on the feedback correction value or the learning value of the air-fuel ratio feedback correction value, the engine is actually diagnosed as having an abnormality.
[0013]
  With this configuration, when it is diagnosed that there is an abnormality in the engine based on the actual generated torque during the transition to lean operation or after the transition to lean operation, it is not immediately diagnosed that the engine is truly abnormal. Since the air-fuel ratio feedback control is performed by operating the stoichiometric system, whether or not an abnormality has actually occurred in the engine (fuel supply system) is diagnosed based on the result. It is possible to prevent misdiagnosis due to the effects of input torque, noise, and the like, thereby making it possible to perform a more accurate engine abnormality diagnosis.
[0014]
  Claim 7In the invention described in, when the engine is diagnosed as having an abnormality, the operation at the lean air-fuel ratio in the homogeneous combustion mode or the stratified combustion mode is prohibited.
  With this configuration, when it is diagnosed that there is an abnormality in the engine, the operation at the lean air-fuel ratio in the homogeneous combustion mode or the stratified combustion mode is prohibited. It is possible to prevent adverse effects on
[0015]
  Claim 8In the invention described in, the actual generated torque of the engine is detected based on the angular speed of crank rotation.
  With such a configuration, the actual generated torque of the engine can be detected with high accuracy with a simple and inexpensive configuration using a crank angle sensor.
[0016]
【The invention's effect】
According to the first aspect of the present invention, the engine abnormality is diagnosed on the basis of the actual engine generated torque. For example, it is not based on an air-fuel ratio feedback correction coefficient or a learning value set by air-fuel ratio feedback control. However, since the engine abnormality can be diagnosed, it is possible to diagnose the abnormality of the engine (fuel system) with a simple configuration regardless of whether it is during stoichiometric operation or lean operation. For this reason, it becomes possible to prevent adverse effects on flammability, operability and the like due to engine abnormality.
[0017]
According to the second and third aspects of the invention, the engine abnormality is diagnosed on the basis of the target torque and the actual engine generated torque. Regardless of this, it is possible to diagnose an abnormality in the engine (fuel system) with high accuracy.
According to the fourth aspect of the present invention, in a so-called in-cylinder direct fuel injection type internal combustion engine that directly injects fuel into the cylinder (inside the cylinder), the fuel is directly supplied into the cylinder. The delay is small and sensitive to abnormalities in the fuel supply amount, and during lean operation, the relationship between the air-fuel ratio (fuel supply amount) and the generated torque is linear, so the combustibility and generated torque are sensitive to abnormalities in the fuel supply amount. However, according to the present invention, it is possible to prevent such a concern in advance.
[0018]
According to the invention described in claim 5, while the engine is operating in the stratified combustion mode (combustion mode in which fuel is supplied into the cylinder during the intake stroke), the above-mentioned concern is further increased. It is possible to avoid such concerns.
According to the sixth aspect of the present invention, when the engine is operated at a lean air-fuel ratio (lean operation), the fuel supply amount becomes abnormal regardless of the fuel injection type engine in the intake port or the direct fuel injection type engine in the cylinder. Although the combustibility and the generated torque change sensitively, the engine abnormality cannot be diagnosed based on the air-fuel ratio feedback correction value or the learned value as in the stoichiometric operation. Even when an abnormality occurs during the transition to the lean operation or during the lean operation, this can be diagnosed with high accuracy, so that, for example, adverse effects on the lean operation can be prevented.
[0019]
According to the seventh aspect of the present invention, the abnormality diagnosis based on the torque can be performed with high accuracy regardless of the environmental conditions, and therefore the abnormality diagnosis accuracy can be further improved.
According to the eighth aspect of the present invention, when it is diagnosed that there is an abnormality in the engine based on the actual generated torque during the transition to the lean operation or after the shift to the lean operation, immediately when the engine is truly abnormal. Instead of diagnosing, the air-fuel ratio feedback control is performed by operating at stoichiometry, and based on the result, whether or not an abnormality has actually occurred in the engine (fuel supply system) is diagnosed. It is possible to prevent erroneous diagnosis due to the influence of reverse input torque, noise, etc. from the drive wheels, and therefore, it is possible to perform more accurate engine abnormality diagnosis.
[0020]
According to the ninth aspect of the present invention, when it is diagnosed that the engine is abnormal, the operation at the lean air-fuel ratio in the homogeneous combustion mode or the stratified combustion mode is prohibited. Adverse effects on performance and drivability can be prevented.
According to the invention described in claim 10, the actual generated torque of the engine can be detected with high accuracy with a simple and inexpensive configuration using a crank angle sensor.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 2 shows a system configuration according to the first embodiment of the present invention.
An accelerator opening sensor 1 serving as an accelerator operation amount detection means detects an accelerator pedal depression amount that is depressed by the driver as an engine load (engine torque) desired by the driver.
[0022]
The crank angle sensor 2 as the engine rotation speed detection means generates a position signal for each unit crank angle and a reference signal for each cylinder stroke phase difference, and measures the number of occurrences of the position signal per unit time, or The engine speed can be detected by measuring the reference signal generation period.
The air flow meter 3 detects the amount of intake air to the engine 4 (intake air amount per unit time = intake air flow rate).
[0023]
The water temperature sensor 5 detects the engine coolant temperature.
The engine 4 is driven by a fuel injection signal and is provided with a fuel injection valve 6 for supplying and injecting fuel, and an ignition plug 7 that is attached to the combustion chamber and ignites, and an intake passage 8 of the engine 4 is provided with a throttle A valve 9 is provided, and a throttle valve control device 10 capable of electronically controlling the opening degree of the throttle valve 9 is provided.
[0024]
Detection signals from the various sensors are input to the control unit 11, which controls the throttle via the throttle valve control device 10 in accordance with the operating state detected based on the signals from the sensors. The opening degree of the valve 9 is controlled, the fuel injection valve 6 is driven to control the fuel injection amount (fuel supply amount), the ignition timing is set, and the ignition plug 7 is ignited at the ignition timing. .
[0025]
Here, an example of engine control (torque demand) performed by the control unit 11 of the present embodiment will be described based on the functional block diagram of FIG. Note that, as will be described below, the control unit 11 is provided with the functions of target torque calculation means, control means, generated torque detection means, and abnormality diagnosis means according to the present invention in software.
[0026]
A target engine torque calculation unit A serving as target torque calculation means receives an accelerator operation amount APS, an engine rotational speed Ne, an externally required torque (auxiliary operating torque of an air conditioner, power steering, alternator, etc.), etc., and is determined by these. The target engine torque tTe corresponding to the operating state is calculated.
The calculated target engine torque tTe is input, and an injection pulse signal having a fuel injection pulse width TI obtained by a predetermined calculation based on the target engine torque tTe is output to the fuel injection valve 6, and the fuel The injection valve 6 is driven and a fuel amount corresponding to the target air-fuel ratio is supplied by injection.
[0027]
In this way, the target air-fuel ratio is maintained by controlling the intake air amount and the fuel supply amount by controlling the throttle valve opening via the throttle valve control device 10 to the respective target values. Thus, while satisfying the exhaust purification performance, fuel consumption, etc., it is possible to obtain a required target engine torque and to ensure good driving performance.
By the way, for example, in a case where combustion is performed under a lean air-fuel ratio (λ = 30 to 40) as in a so-called direct in-cylinder fuel injection type engine in which fuel is directly injected into the in-cylinder (combustion chamber). However, since the sensitivity of engine output and drivability is large with respect to the fuel amount, even if a small amount of fuel is abnormal, there is a possibility that the influence on the combustibility and drivability will increase. In addition, there is a similar concern when the lean operation is performed by the intake port injection.
[0028]
For this reason, the present embodiment includes an abnormality diagnosis means for diagnosing an abnormality in the engine (fuel supply system). The abnormality diagnosing means of this embodiment can diagnose an abnormality not only during lean operation but also during operation under stoichiometric air-fuel ratio (stoichiometric operation).
That is, as shown in FIG.
A target engine torque phase correction unit B is provided, whereby the target engine torque tTe calculated by the target engine torque calculation unit A is phase-corrected (weighted average processing or the like) to obtain a target engine torque RTe after phase correction. . Note that phase correction based on the operating angle (switching state) of the VTC (variable valve timing device), the change state of the EGR rate, and the like can also be included.
[0029]
And the target engine torque change calculating part C is provided, and the change amount ΔRTe of the target engine torque RTe after phase correction is thereby obtained.
On the other hand, a generated torque change calculation (detection) unit E for detecting actual generated engine torque change (Δ torque) is provided.
The generated torque change calculation unit E estimates (detects) the generated torque change based on the angular velocity (angular acceleration) of the crankshaft detected based on the detection signal of the crank angle sensor 2.
[0030]
That means
Torquen by cylinder TORQUEn (N ・ m) ＝ K × (T1 (i) −T2 (i)) × Ne^Three+ OFFSET
From this equation, the generated torque (N · m) is obtained for each cylinder, and the change in this is obtained.
Here, K: constant, OFFSET; table data by rotation is searched and set (since there is sensitivity to rotation for OFFSET).
[0031]
That is, the angular acceleration is obtained by measuring average angular velocities T1 (i) and T2 (i) at two predetermined crank angle widths during the expansion stroke of 180 deg and calculating the difference (see FIG. 4).
ΔT (n) = T1 (i) −T2 (i)
ΔT (n); angular acceleration of expansion stroke cylinder
Note that ΔT is proportional to the torque generated by the expansion stroke cylinder which has been measured.
[0032]
Here, the correlation between the generated torque TORQUEn (N · m) and Δω (= ΔT (n) = T1 (i) −T2 (i)) is shown in FIG. 5 (experimental result).
Specifically, in the engine generated torque estimation calculation (estimation detection) unit F, based on the detection signal of the crank angle sensor 2, the average angular velocity at two predetermined crank angle widths (for example, 0.25 μsec) during the expansion stroke 180 deg. T1 (i) and T2 (i) are measured, and the torque for each cylinder “TORQUEn (N · m) = K × (T1 (i) −T2 (i)) × Ne^Three+ OFFSET ”is calculated.
[0033]
The generated torque change calculation unit E calculates the torque change (Δ torque) obtained by the engine generated torque estimation calculation (estimation detection) unit F.
The torque change determination unit (abnormality diagnosis unit) D compares Δtorque calculated by the generated torque change calculation unit E with ΔRTe calculated by the target torque change calculation unit C, and | Δtorque−ΔRTe If |> reference value torque (predetermined value, diagnostic reference value), it is determined that the deviation between the target torque and the actual generated torque is large, and the fuel injection amount that achieves the target torque is not actually injected. Therefore, it is diagnosed that there is some abnormality in the fuel supply system. In addition, | Δtorque−ΔRTe |> reference value torque can be configured such that | Δtorque−ΔRTe | is integrated in a certain time width, and the value is compared with the diagnostic reference value (that is, human) It is preferable to diagnose an abnormality of the fuel supply system (deterioration of driving performance) in accordance with the sensitivity of the engine).
[0034]
Then, as shown in FIG. 3, when an abnormality diagnosis is made, for example, the shift to lean operation (including both stratified combustion and homogeneous combustion) is prohibited, the homogeneous stoichiometric operation is continued, and a warning lamp Etc. are lit to make the driver recognize the vehicle.
In the present embodiment, the change amount of the target torque (change amount per unit time) is compared with the actual change amount of generated torque (change amount per unit time). In order to detect whether or not the target torque is actually obtained with high accuracy regardless of the environmental conditions, etc. In the case where it is not necessary to do so, it is possible to adopt a configuration in which the target torque change is compared with the actual generated torque.
[0035]
The actual generated torque can be detected using, for example, a torque sensor (strain gauge) or the like, and the actual amount of change in generated torque can also be detected based on this.
Thus, according to the present embodiment, when the target torque is compared with the actual engine generated torque and the deviation between the target torque and the actual generated torque is large, the fuel system is abnormal. Since the diagnosis is made, it is possible to diagnose the abnormality of the engine (fuel system) with a simple configuration. For this reason, it becomes possible to prevent adverse effects on drivability.
[0036]
By the way, as in the present embodiment, if the change amount of the target torque (change amount per unit time) is compared with the actual change amount of generated torque (change amount per unit time), the existing torque change amount is changed. As described above, since abnormality can be diagnosed regardless of environmental conditions, abnormality diagnosis accuracy can be further improved.
If the abnormality diagnosis of this embodiment is performed during lean combustion (for example, during the transition from the stoichiometric operation to the lean operation or during the lean operation), the abnormality of the fuel system that occurs during the transition or during the lean operation is diagnosed. Therefore, it can fail against flammability and operability due to fuel system abnormalities in lean operation (adverse effects such as misfires and accidental acceleration when fuel is abnormal on the increase side). Safe processing (lean operation prohibition, etc.) can be performed.
[0037]
That is, during the transition to the lean operation or during the lean operation, the air-fuel ratio control is open control (feed forward control), and thus is set by air-fuel ratio feedback control using the oxygen sensor 12 as in, for example, stoichiometric operation. It cannot be diagnosed that there is an abnormality in the fuel system based on the fact that the air-fuel ratio feedback correction value or the learned value (these are values corresponding to the deviation between the theoretical air-fuel ratio and the actual air-fuel ratio) is greater than a predetermined value. However, according to the present embodiment, since the abnormality is diagnosed by comparing the target torque and the actual engine generated torque, {intake of air even during transition to lean operation or during lean operation In-port injection type, in-cylinder direct injection type, regardless of combustion mode (stratification, homogeneous), target air-fuel ratio}, it is possible to diagnose an abnormality in the fuel system easily and accurately. This is because made to wear. An abnormality diagnosis during stoichiometric operation is also possible.
[0038]
In other words, conventionally, an abnormality of the fuel system is diagnosed based on the air-fuel ratio feedback correction value or the learning value during the stoichiometric operation, and when there is such an abnormality, for example, the shift to the lean operation is prohibited based on the diagnosis result. However, when an abnormality occurred during the transition to the lean operation or during the lean operation, the abnormality could not be diagnosed. However, in the present embodiment, even when an abnormality occurs during the transition to the lean operation or during the lean operation, this can be diagnosed with high accuracy, so that, for example, an adverse effect on the drivability is prevented in advance. It becomes possible to do.
[0039]
By the way, for example, combustion is usually performed in a homogeneous mixture (a state where fuel is evenly distributed throughout the combustion), and a spark plug is placed in the combustion chamber in a predetermined operation state (low rotational speed, low load state, etc.). (1) composed of a mixture of combustible mixture ratios that can be ignited by the above, and a combustible mixture ratio that is difficult to be ignited by an air layer containing EGR or a spark plug, but can be burned by the combustion flame in the layer (1) The stratified mixture of the mixture (2) of the mixture is formed, combustion is realized at an extremely lean air-fuel ratio (an air-fuel ratio in the vicinity of the lean limit), and fuel consumption, etc. due to the pumping loss reduction effect, etc. During the transition to stratified combustion in an engine designed to improve (so-called combustion chamber direct fuel injection gasoline engine) or during stratified combustion, even if a small amount of fuel is abnormal, it has an effect on combustibility compared to homogeneous combustion. Greater driving performance Although negative effects (degradation of driveability caused by inadvertent acceleration or misfire) increases, the can abnormality diagnosis during the transition or during stratified combustion to such stratified charge combustion in the present embodiment, an extremely effective technique.
[0040]
Next, a second embodiment of the present invention will be described.
The second embodiment is an example of a routine that allows or prohibits the transition from stoichiometric operation to lean operation based on the diagnosis result of the abnormality diagnosis of the engine (fuel supply system) described in the first embodiment. It is about.
During the stoichiometric operation, air-fuel ratio feedback control is performed so that the actual air-fuel ratio is maintained in the vicinity of the theoretical air-fuel ratio based on the detection value of the oxygen sensor 12 in FIG. The lean operation (including both homogeneous and stratified) is an engine that performs open control of the air-fuel ratio using the learned value (deviation between the theoretical air-fuel ratio and the actual air-fuel ratio) learned during the air-fuel ratio feedback control. Is applicable. However, the present invention can also be applied to an apparatus that performs open control during lean operation without using a learning value acquired during stoichiometric operation.
[0041]
Specifically, the flowchart of FIG. 6 is executed.
In step (denoted as S in the figure, the same applies hereinafter) 1, it is determined whether or not a lean transition condition is satisfied.
For example, the determination can be made based on whether or not the following conditions are satisfied in addition to the operation state entering the operation region in which the lean operation is performed.
[0042]
(1) The learning value used during lean operation has been acquired. That is, the base learning (learning without purge) has been completed.
(2) The deviation between the normal learning value (learning value for stoichiometric operation) and the base learning value (high-speed learning value performed for permitting the shift to lean combustion) is not more than a predetermined value. Note that, as the base learning, for example, as in normal learning, the operation region is not divided into a plurality of loads and rotation speeds at the time of stoichiometry and a learning value is acquired for each operation region, but the lean combustion is quickly performed. In order to allow the transition, the deviation between the command fuel supply amount and the actual fuel supply amount is learned at at least two points at the time of stoichiometry, and the command fuel supply amount at the lean time is determined by the corresponding fuel supply amount. There is a learning control that corrects by the deviation.
[0043]
In the above (1) and (2), the learning value that is the result of the air-fuel ratio feedback control performed during the stoichiometric operation is used, and the air-fuel ratio is feedforward (open) controlled during the lean operation. If it is not properly acquired, there is a possibility that a deviation may occur between the target air-fuel ratio and the actual air-fuel ratio, so as to avoid adversely affecting lean combustion / operability.
[0044]
(3) The accumulated value of the evaporation purge flow rate is not less than the predetermined value. This is to prevent the purge process from being performed during lean and adversely affecting lean combustion / operability.
(4) The amount of gasoline mixed in the blow-by gas is estimated, and the amount mixed is not more than a predetermined value. This is to prevent the gasoline mixed in the blow-by gas from adversely affecting lean combustion and drivability.
[0045]
(5) Failure diagnosis (disconnection, output deterioration, etc.) for each part is normal. For example, the determination is based on failure determination based on output signals of the oxygen sensor 12 and the crank angle sensor 2 or failure determination based on the drive current value of the drive solenoid of the fuel injection valve 6.
If YES, the process proceeds to Step 2, and if NO, the process returns to Step 1. In step 2, an air-fuel ratio feedback correction coefficient (air-fuel ratio correction coefficient) α (a value corresponding to the deviation between the theoretical air-fuel ratio and the actual air-fuel ratio) of the air-fuel ratio feedback control based on the oxygen sensor output during stoichiometric operation is within a predetermined range. And the learning value {learning control correction coefficient. It is determined whether or not the deviation of the air-fuel ratio feedback correction coefficient α from the reference value (the value corresponding to the theoretical air-fuel ratio) is within a predetermined range.
[0046]
If YES, the process proceeds to step 3, and if NO, the process returns to step 1. That is, in step 2, the deviation between the target air-fuel ratio during the stoichiometric operation and the actual air-fuel ratio actually achieved with the command fuel injection amount at which the target air-fuel ratio will be obtained is within a predetermined range. If the deviation is within a predetermined range, it is determined that there is no abnormality in the fuel supply system and the shift to the lean operation is permitted to proceed to step 3, while the deviation is If it is not within the predetermined range, there is a possibility that there is some abnormality in the fuel supply system, so if the feedforward control of the air-fuel ratio is performed during the lean operation using the learning value acquired including the abnormal state, Since there is a possibility of adversely affecting lean combustion and drivability, the process returns to step 1 without permitting the shift to lean operation.
[0047]
In step 3, the operation is shifted to lean operation (including both stratified combustion and homogeneous combustion).
In step 4, the torque change (Δtorque) obtained from Δω = angular acceleration fluctuation is calculated by the method described in the first embodiment.
In step 5, a change in target torque (ΔRTe) is calculated.
[0048]
In step 6, it is determined whether or not | ΔRTe−Δtorque |> predetermined value. If YES, the actual torque has not followed the target torque, so there may be some abnormality in the fuel supply system during the shift to lean operation or after the shift to lean operation (during lean operation). Since there is, proceed to Step 7. On the other hand, if NO, the actual torque following the target torque is obtained, so it is determined that there is no abnormality in the fuel supply system, and the routine proceeds to step 10.
[0049]
In Step 10, while the operation state is in the operation region where the lean operation is performed, the process returns to Step 3 and the lean operation is continued while monitoring the Δ torque. On the other hand, when the operation state is outside the operation region where the lean operation is performed, the lean operation is set as the stoichiometric operation in step 11 and the process returns to step 1.
In Step 7, there is a possibility that an abnormality has occurred in the fuel supply system. During lean operation, even if a small amount of fuel is abnormal, there is a risk that the sensitivity of flammability and drivability will be large and the drivability may be impaired. Is temporarily stopped and shifted to stoichiometric operation.
[0050]
In step 8, the air-fuel ratio feedback correction coefficient (air-fuel ratio correction coefficient) α, which is the result of the air-fuel ratio feedback control based on the oxygen sensor output during the stoichiometric operation, is within a predetermined range, and the learning value is within the predetermined range. It is determined again whether or not. If YES, there is no abnormality in the fuel supply system, and it is determined that the determination result in step 6 is due to other factors (for example, the influence of reverse input torque, noise, etc. from the drive wheels), and the process returns to step 1. Then, the transition permission determination to the lean operation is executed again.
[0051]
On the other hand, if NO, it is determined that an abnormality has occurred in the fuel supply system, and execution / shift to lean operation is prohibited in step 9 and this flow is terminated. At the same time, a warning light or the like can be turned on to prompt the driver to perform processing or the like.
Thus, according to the present embodiment, during the stoichiometric operation, the abnormality of the engine (fuel supply system) is diagnosed using the air-fuel ratio feedback control result (the air-fuel ratio feedback correction coefficient α and the learning value). While permitting / prohibiting the transition to lean operation, the target torque is compared with the actual torque during transition to lean operation or after lean operation (during lean operation) when air-fuel ratio feedback control cannot be performed. (Fuel supply system) abnormality is diagnosed and lean operation is allowed / prohibited, so when the fuel supply system is abnormal, the lean operation is definitely prohibited regardless of whether it is during stoichiometric operation or lean operation be able to. Therefore, it is possible to reliably prevent deterioration of combustibility and drivability when the lean operation is performed when the fuel supply system is abnormal.
[0052]
In this embodiment, when it is diagnosed that there is a possibility that the engine (fuel supply system) is abnormal based on the comparison result between the target torque and the actual torque during or after the shift to the lean operation. Instead of immediately prohibiting the execution of lean operation, the engine is operated again with stoichiometric control to perform air-fuel ratio feedback control. Based on the result, whether or not an abnormality has actually occurred in the engine (fuel supply system) is determined. Since the diagnosis is made, for example, it is possible to prevent erroneous diagnosis due to the influence of reverse input torque, noise, etc. from the drive wheels. Therefore, it is possible to diagnose the abnormality of the fuel supply system with higher accuracy.
[0053]
By the way, the present invention can be applied to all systems that control the engine to the target torque, and is not limited to the system (function) shown in FIG.
In each of the above embodiments, the configuration has been described as diagnosing engine abnormality based on the target torque and the actual generated torque. However, the present invention is not limited to this, and the actual generated torque is not limited thereto. And a predetermined value (predetermined value) or the like, that is, a configuration for diagnosing engine abnormality based on actual generated torque.
[0054]
In the second embodiment, the engine abnormality is diagnosed based on the air-fuel ratio feedback correction value and the learning value during the stoichiometric operation, and the engine abnormality is diagnosed based on the actual torque during the lean operation. When an abnormality is diagnosed during operation, if the engine is diagnosed to be abnormal even if it is diagnosed by an abnormality diagnosis based on an air-fuel ratio feedback correction value or a learning value by performing stoichiometric operation, the engine is considered to be truly abnormal However, the present invention is not limited to this, and the engine abnormality is diagnosed based on the actual torque regardless of the stoichiometric lean. When an abnormality is diagnosed, the engine is abnormal even if the stoichiometric operation is performed and the abnormality diagnosis is performed using the air-fuel ratio feedback correction value or the learning value. If it is the cross-sectional, the engine is one which can be configured such that diagnosis is truly abnormal.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of the present invention.
FIG. 2 is a system configuration diagram according to the first embodiment of the present invention.
FIG. 3 is a functional block diagram according to the embodiment.
FIG. 4 is an explanatory diagram of a principle of torque detection based on a rotational angular velocity.
FIG. 5 is a correlation diagram of generated torque, Δω, and rotational speed.
FIG. 6 is a flowchart according to the second embodiment of the present invention.
FIG. 7 is a diagram for explaining the sensitivity of torque fluctuation to changes in the air-fuel ratio (for example, fuel supply amount).
[Explanation of symbols]
1 Accelerator operation amount sensor
2 Crank angle sensor
3 Air flow meter
4 engine
5 Water temperature sensor
6 Fuel injection valve
9 Throttle valve
10 Throttle valve control device
11 Control unit
12 Oxygen sensor
A Target engine torque calculator
B Target engine torque phase correction unit
C Target engine torque change calculation unit
D Torque change determination unit (abnormality diagnosis unit)
E Generated torque change calculator
F Generated torque estimation calculation unit

Claims (8)

An engine abnormality diagnosis apparatus characterized in that an engine abnormality diagnosis is performed by comparing a change amount of a target torque per predetermined time with an actual change amount of generated torque during an expansion stroke of the engine. Target torque calculating means for calculating the target torque of the engine;
Control means for controlling the engine so as to achieve the target torque calculated by the target torque calculating means;
Generated torque detection means for detecting the actual generated torque of the engine;
In the expansion stroke of the engine, and the amount of change calculated target torque by the target torque calculation means, a change amount of the actually generated torque detected by said torque detecting means, based on the abnormality diagnosis of the engine Abnormality diagnosis means to be performed;
The engine abnormality diagnosis device according to claim 1 , comprising: The engine abnormality diagnosis device according to claim 1 or 2, wherein the engine is an engine that directly injects fuel into a cylinder. The engine abnormality diagnosis apparatus according to claim 3 , wherein an engine abnormality diagnosis is performed based on an actual torque generated by the engine while the engine is operating in a stratified combustion mode. During operation of the engine at lean air-fuel ratio, the engine according to any one of claims 1 to 4, characterized in that to perform the abnormality diagnosis engine based on the torque actually generated in the engine Abnormality diagnosis device. An air-fuel ratio feedback control means for correcting the fuel supply amount via the air-fuel ratio feedback correction value so as to control the actual air-fuel ratio in the vicinity of the theoretical air-fuel ratio;
When the engine abnormality diagnosis based on the actual generated torque of the engine diagnoses that the engine is abnormal, the engine abnormality diagnosis is performed based on the air-fuel ratio feedback correction value set by the air-fuel ratio feedback control means. The engine abnormality diagnosis based on the air-fuel ratio feedback correction value or the learned value of the air-fuel ratio feedback correction value diagnoses that the engine is truly abnormal when it is diagnosed. The engine abnormality diagnosis device according to any one of claims 1 to 5 . The engine according to any one of claims 1 to 6 , wherein when the engine is diagnosed as being abnormal, operation at a lean air-fuel ratio in a homogeneous combustion mode or a stratified combustion mode is prohibited. Abnormality diagnosis device. The engine failure diagnosis device according to any one of claims 1 to 7 , wherein an actual generated torque of the engine is detected based on an angular velocity of crank rotation.

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