JP5472165B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device that controls an intake air amount during a sensor failure.

  As a control method for an engine mounted on a vehicle, torque base (torque demand) control is known which controls intake air amount, fuel injection amount, ignition timing, etc. based on the magnitude of torque required for the engine. Yes. In the torque-based control, for example, a target value of engine torque is calculated based on the accelerator opening, the engine speed, and the like, and the engine is controlled so as to obtain this target value of torque. Also, in vehicles equipped with external control systems such as automatic transmissions, auto cruise devices, and vehicle stabilizers, output requests from each external control system to the engine are converted into torque and integrated in the engine ECU (engine electronic control unit). The torque behavior of the engine is comprehensively controlled.

  In the calculation of the intake air amount by torque-based control, detection information of various sensors is referred to. For example, the intake flow rate detected by the airflow sensor is used for the estimation calculation of the engine torque, and the throttle opening degree detected by the atmospheric pressure sensor or the intake manifold (intake manifold) pressure sensor is used for the calculation of the target throttle opening degree. Front-rear pressure is used. In some cases, a load during idling of the engine is calculated based on the cooling water temperature detected by the water temperature sensor. Therefore, when these sensors fail or when the detection accuracy is lowered, the calculation accuracy of the engine torque and the throttle opening is lowered, and it may be difficult to improve the controllability of the engine.

  In recent years, an engine having a variable valve mechanism for changing the operation of an intake valve and an exhaust valve has been developed. The variable valve mechanism allows the valve opening / closing timing and opening amount (valve lift amount) to be changed, and the intake air amount is adjusted not only by the throttle valve but also by control of the variable valve mechanism. Therefore, in a state where accurate information cannot be obtained from the sensors, it is difficult to accurately control the operation of the variable valve mechanism.

  In order to solve these problems, a technique for ensuring controllability by setting a control amount at the time of sensor failure in advance has been proposed. For example, Patent Document 1 describes a control device that sets the phase of the intake valve to the most retarded angle and sets the valve lift amount to a predetermined set value when a failure occurs. In this technique, combustion stability is ensured by presetting a value for failure as a control amount of the variable valve mechanism.

JP 2009-250029 A

By the way, in the technique of Patent Document 1, when the vehicle speed is low or the target intake air amount is small, the valve lift amount at the time of sensor failure is gradually changed. That is, fluctuations in engine torque are suppressed by preventing sudden changes in the intake air amount, and drivability is ensured.
However, the amount of intake air introduced into the cylinder through the intake valve is not necessarily proportional to the valve lift amount. For example, when the valve lift amount is gradually increased from the minimum amount, the air easily enters the cylinder from the intake port at the beginning, and the intake air amount is likely to increase in combination with the intake inertia action. On the other hand, when the valve lift amount is increased to some extent, the intake valve opening timing is retarded, so that part of the air in the cylinder flows backward to the intake port side and the intake air amount is likely to decrease.

  Therefore, even if the valve lift amount is gradually increased, the intake air amount does not increase monotonously with respect to the change in the valve lift amount, but changes in a decreasing direction with a certain valve lift amount as a boundary. That is, since the change direction of the valve lift amount and the change direction of the intake air amount do not necessarily match, an unnecessary increase / decrease change may occur in the intake air amount in the process of changing the valve lift amount. This can cause unintended vehicle behavior.

One of the purposes of the present case was created in view of the above-described problems, and is to suppress torque fluctuation during sensor failure in controlling the intake air amount of the engine.
The present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiments for carrying out the invention described later, and other effects of the present invention are to obtain a function and effect that cannot be obtained by conventional techniques. Can be positioned.

  (1) The engine control device disclosed herein sets a first target amount as a target lift amount of the intake valve based on detection information of a sensor attached to the engine, and sets the lift amount of the intake valve to the first amount. Valve lift control means for controlling to one target amount is provided. Further, there is provided valve lift setting means for setting, as the second target amount, a lift amount at which the engine torque becomes maximum at the same throttle opening. Furthermore, a first tailing control means for performing first tailing control for gradually changing the lift amount to the second target amount at the time of failure of the sensor is provided.

The first tailing control is, for example, control for changing the lift amount to the second target amount over a predetermined time. Or it is control which changes the said lift amount to said 2nd target amount, restrict | limiting the change amount per unit time of the said lift amount to below predetermined amount. In any of these controls, the lift amount gradually changes to the second target amount.
Note that the lift amount at which the engine torque is the largest means the lift amount at which air is most likely to enter the cylinder in the current operating state of the engine.

  (2) It is preferable that a first control opening of the throttle valve is set based on detection information of the sensor, and a throttle control means for controlling the throttle opening to the first target opening is provided. In this case, it is preferable to include a throttle setting means for setting the second target opening of the throttle valve based on the accelerator opening in a range at least equal to or less than the first target opening. Furthermore, it is preferable that a second tailing control means for performing second tailing control for gradually changing the throttle opening to the second target opening at the time of failure of the sensor is provided.

  The second tailing control is control for changing the throttle opening to the second target opening over a predetermined time, for example. Or it is control which changes the said throttle opening to said 2nd target opening, restrict | limiting the variation | change_quantity per unit time of the said throttle opening to predetermined value or less. In any of these controls, the throttle opening gradually changes to the second target opening.

(3) Further, it is preferable that the first tailing control means simultaneously performs the first tailing control at the same tailing time as the second tailing control by the second tailing control means.
(4) Moreover, it is preferable that the said valve lift setting means sets said 2nd target amount based on an engine speed.

(5) Alternatively, it is preferable that the valve lift setting means sets the second target amount based on a valve timing of the intake valve. The second target amount may be set based on the amount of air introduced into the cylinder of the engine, the charging efficiency, or the like.
(6) The sensor preferably includes at least one of an air flow sensor, an intake manifold pressure sensor, an atmospheric pressure sensor, and a cooling water temperature sensor.

  According to the disclosed engine control device, by setting the lift amount at which the engine torque is maximized under the same throttle opening condition as the second target amount, it is possible to introduce the intake air into the cylinder when the sensor fails (entering). Ease). Moreover, the fluctuation | variation of the engine torque by 1st tailing control can be increased monotonously, and it can make it easy to stabilize a vehicle behavior.

It is a figure showing an example of composition of an engine to which a control device concerning one embodiment was applied. It is a figure which illustrates the block configuration of this control apparatus, (a) is a 1st target opening degree setting part, (b) is a 2nd target opening degree setting part, (c) is a 1st target control angle setting part, ( d) shows a second target control angle setting unit. It is a graph for demonstrating the valve characteristic which concerns on this control apparatus. It is an example of the flowchart of control implemented by this control apparatus. It is a graph for demonstrating the control effect | action by this control apparatus, (a) is throttle opening, (b) is a fail flag, (c) is a valve lift amount, (d) shows the fluctuation | variation of an engine torque.

  The control device will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment.

[1. Device configuration]
[1-1. engine]
The engine control apparatus of this embodiment is applied to the vehicle-mounted engine 10 shown in FIG. Here, one of the plurality of cylinders 14 provided in the multi-cylinder engine 10 is shown. A spark plug 13 is provided at the top of the cylinder 14 with its tip projecting toward the combustion chamber. An intake port 11 and an exhaust port 12 are provided on the top surface of the combustion chamber on the cylinder head side.

  An intake valve 8 for opening and closing the inlet of the intake port 11 and an exhaust valve 9 for opening and closing the inlet of the exhaust port 12 are provided on the top surface of the combustion chamber. An injector 18 for injecting fuel is provided in the intake port 11. The intake port 11 and the combustion chamber are communicated or closed by opening and closing the intake valve 8, and the exhaust port 12 and the combustion chamber are communicated or blocked by opening and closing the exhaust valve 9.

  The upper ends of the intake valve 8 and the exhaust valve 9 are respectively connected to one end of a rocker shaft in the variable valve mechanism 6. The rocker shaft is a rocking member that is pivotally supported by the rocker arm. A cam supported on the camshaft is provided at the other end of the rocker shaft. As a result, the rocker shaft swing pattern corresponds to the shape of the cam (cam profile). The variable valve mechanism 6 will be described later.

  An intake manifold 20 (hereinafter referred to as intake manifold) is provided upstream of the intake port 11 in the intake air flow. The intake manifold 20 is provided with a surge tank 21 for temporarily storing air flowing toward the intake port 11 side. The intake manifold 20 on the downstream side of the surge tank 21 is formed to branch toward the intake ports 11 of the plurality of cylinders 14, and the surge tank 21 is located at the branch point. The surge tank 21 functions to mitigate intake pulsation and intake interference generated in each cylinder 14.

A throttle body 22 is connected to the upstream end of the intake manifold 20. An electronically controlled throttle valve 7 is built in the throttle body 22 and the amount of air flowing to the intake manifold 20 is adjusted in accordance with the opening of the throttle valve 7 (throttle opening θ _TH ). This throttle opening θ _TH is electronically controlled by an engine ECU 1 described later.

An intake passage 23 is connected further upstream of the throttle body 22. The intake passage 23, an air flow sensor 25 is provided for detecting the intake air flow rate Q _IN. Information on the intake air flow rate Q _IN detected here is transmitted to the engine ECU 1. An air filter 24 is interposed further upstream of the intake passage 23. Thus, fresh air filtered by the air filter 24 is supplied to the cylinder 14 of the engine 10 via the intake passage 23 and the intake manifold 20.

An atmospheric pressure sensor 27 and an intake manifold pressure sensor 26 for detecting the pressure at each position are provided on the upstream side and the downstream side of the throttle valve 7. The atmospheric pressure sensor 27 detects the atmospheric pressure P _B (upstream pressure of the throttle valve 7), and the intake manifold pressure sensor 26 detects the intake manifold pressure P _A (downstream pressure of the throttle valve 7 and pressure in the surge tank). It is to detect. These intake manifold pressure sensor 26 and the intake manifold pressure information P _A and the atmospheric pressure P _B detected by the atmospheric pressure sensor 27 is transmitted to the engine ECU 1.

The piston 16 that reciprocates in the cylinder 14 is connected to the crankshaft 17 via a connecting rod. The connecting rod is a link member that converts the reciprocating motion of the piston 16 into the rotational motion of the crankshaft 17. The crankshaft 17, the crank angle sensor 29 for detecting the rotation angle theta _CR is provided. Note that the amount of change in the rotation angle θ _CR per unit time is proportional to the engine speed Ne. Therefore, it can be said that the crank angle sensor 29 has a function of detecting the engine speed Ne of the engine 10. Information of the engine speed Ne detected (or calculated) here is transmitted to the engine ECU 1. The engine ECU 1 may calculate the engine speed Ne based on the rotation angle θ _CR detected by the crank angle sensor 29.

An accelerator pedal sensor 30 for detecting an accelerator opening degree θ _AC corresponding to the amount of depression of the accelerator pedal is provided at an arbitrary position of the vehicle on which the engine 10 shown in FIG. 1 is mounted. The accelerator opening degree θ _AC is a parameter corresponding to the driver's acceleration request. Information on the accelerator opening θ _AC detected here is transmitted to the engine ECU 1.

  A water jacket 15 serving as a cooling water flow path is provided around the cylinder 14. The cooling water is a refrigerant for cooling the engine 10 and circulates in a cooling circuit including a water jacket 15, a cooling water flow path (not shown), a radiator, and the like. Further, a water temperature sensor 28 for detecting the cooling water temperature W is provided at an arbitrary position in the cooling circuit. The cooling water temperature W is a parameter related to the friction between the cylinder 14 and the piston 16. Information on the coolant temperature W detected here is transmitted to the engine ECU 1.

The engine ECU 1 (Engine Electronic Control Unit) is an electronic control device that controls the amount of air supplied to each cylinder 14 of the engine 10, the amount of fuel injection, and the ignition timing. For example, a microprocessor, ROM, RAM, etc. are integrated. Configured as an LSI device or embedded electronic device. Here, torque base control based on the magnitude of torque required for the engine 10 is performed. Specific control objects of the engine ECU 1 include the amount of fuel injected from the injector 18 and the injection timing, the ignition timing at the spark plug 13, the opening θ _TH of the throttle valve 7, and the like. In the present embodiment, its function will be described by paying attention to engine torque control (intake air amount control) by adjusting the throttle opening θ _TH and the valve lift amount.

[1-2. Variable valve mechanism]
A variable valve mechanism 6 is connected to each of the intake valve 8 and the exhaust valve 9. The variable valve mechanism 6 is a mechanism that changes the maximum valve lift amount and the valve timing individually or in conjunction with each of the intake valve 8 and the exhaust valve 9. Upper ends of the intake valve 8 and the exhaust valve 9 are connected to a rocker arm that is pivotally supported by a rocker shaft inside the variable valve mechanism 6. Thereby, the intake valve 8 and the exhaust valve 9 are reciprocated in the vertical direction by the rocking of the respective rocker shafts.

  On the other hand, the variable valve mechanism 6 is provided with a mechanism for changing the rocking amount and rocking timing of the rocker shaft. As shown in FIG. 1, the variable valve mechanism 6 includes a variable valve lift mechanism 6a and a variable valve timing mechanism 6b.

  The variable valve lift mechanism 6 a is a mechanism that continuously changes the maximum valve lift amount of the intake valve 8 and the exhaust valve 9. This variable valve lift mechanism 6a has a function of changing the magnitude of the swing transmitted from the cam fixed to the camshaft to the rocker arm. A specific structure for changing the magnitude of the rocker arm swing is arbitrary.

  For example, a structure may be considered in which a swinging member is separately interposed between a cam fixed to the camshaft and a rocker arm, and the rotational movement of the camshaft is converted into the swinging motion of the rocker arm via the swinging member. It is done. In this case, by moving the position of the swing member and changing the contact position with the cam, the swing amount of the swing member changes and the swing amount of the rocker arm also changes. As a result, the valve lift amount can be continuously changed.

Hereinafter, the angle change amount from the reference position of the swinging member with respect to the rocker shaft is referred to as a control angle θ _VVL . The control angle θ _VVL is a parameter corresponding to the valve lift amount, and the reference position of the swing member is set so that the valve lift amount increases as the control angle θ _VVL increases. The variable valve lift mechanism 6a controls the valve lift amount to an arbitrary value by adjusting the control angle θ _VVL .

  The variable valve timing mechanism 6 b is a mechanism that changes the opening / closing timing (valve timing) of the intake valve 8 and the exhaust valve 9. The variable valve timing mechanism 6b has a function of changing the rotational phase of the cam or camshaft that causes the rocker arm to swing. By changing the rotational phase of the cam or camshaft, it is possible to continuously shift the rocker arm swinging timing with respect to the rotational phase of the crankshaft 17.

Hereinafter, a change amount of the phase angle indicating how much the actual camshaft phase angle is advanced or retarded from the reference camshaft phase angle is referred to as a phase angle _θVVT . The phase angle θ _VVT is a parameter corresponding to the valve timing. The variable valve timing mechanism 6b arbitrarily controls the valve timing by adjusting the phase angle θ _VVT . The variable valve timing mechanism 6b is provided with a phase detector that detects (or calculates) the phase angle θ _VVT . The phase angle θ _VVT obtained here is transmitted to the engine ECU 1.

[2. Control configuration]
An air flow sensor 25, an intake manifold pressure sensor 26, an atmospheric pressure sensor 27, a water temperature sensor 28, a crank angle sensor 29, and an accelerator pedal sensor 30 are connected to the input side of the engine ECU 1. Based on information from these sensors, the engine ECU 1 calculates a target value corresponding to the torque achieved by adjusting the intake air amount, among the torque required for the engine 10, as the target torque. Further, the engine ECU 1 sets the throttle opening θ _TH of the throttle valve 7 and the control angle θ _VVL of the variable valve lift mechanism 6 a so that an amount of air necessary for generating the target torque is introduced into the cylinder 14. Control.

  As shown in FIG. 1, the engine ECU 1 is provided with a sensor failure determination unit 2, a throttle control unit 3, and a valve lift control unit 4. Each function of the sensor failure determination unit 2, the throttle control unit 3, and the valve lift control unit 4 may be realized by an electronic circuit (hardware), may be programmed as software, or these functions may be realized. Some of them may be provided as hardware, and the other part may be software.

[2-1. Sensor failure determination unit]
The sensor failure determination unit 2 determines whether various sensors attached to the engine 10 are operating properly. The failure here includes not only a failure of the sensor but also a problem that the engine ECU 1 cannot correctly read the detection information of the sensor. Specific examples of the failure state include a state in which the detected value is not accurate due to adhesion of moisture and foreign matter to the sensor, and a state in which information input to the engine ECU 1 is not accurate due to fluctuations in noise and a reference voltage (vehicle body ground voltage). Conceivable.

  The sensor failure determination unit 2 determines each failure of the air flow sensor 25, the intake manifold pressure sensor 26, the atmospheric pressure sensor 27, and the water temperature sensor 28 using, for example, a known determination method, and any one of these sensors is in a failure state. When it is, the fail flag F is set to F = 1 (ON). On the other hand, when all the sensors are not in the fail state, the fail flag F is set to F = 0 (off). The value of the fail flag F set here is transmitted to the throttle control unit 3 and the valve lift control unit 4.

[2-2. Throttle control unit]
The throttle control unit 3 adjusts the intake air amount by controlling the throttle opening θ _TH . Here, a first target opening setting unit 3a for setting a first target opening θ _TH1 that is a target value of the throttle opening θ _TH at the time of non-failure, and a second target opening that is a target value at the time of failure a second target opening setting portion 3b for setting a theta _TH2, are provided with opening control section 3c.

Detection values of the air flow sensor 25, the intake manifold pressure sensor 26, the atmospheric pressure sensor 27, and the water temperature sensor 28 are used for the calculation of the first target opening degree _θTH1 set by the first target opening degree setting unit 3a. On the other hand, the second target value θ _TH2 set by the second target opening setting unit 3b is a control target value at the time of failure, and is calculated without using the detection value of the sensor.

As shown in FIG. 2A, the first target opening setting unit 3a (throttle control means) includes a target torque calculation unit 31, a target flow rate calculation unit 32, an actual torque calculation unit 33, a flow rate calculation unit 34, and a normal operation. An hour opening setting unit 35 is provided.
The target torque calculation unit 31 determines the coolant temperature W detected by the water temperature sensor 28, the engine speed Ne detected (or calculated) by the crank angle sensor 29, the accelerator opening θ _AC detected by the accelerator pedal sensor 30, and the like. Based on this, the target torque Pi _TGT is calculated. This target torque Pi _TGT is a value obtained by converting the target value of the torque in the intake air amount control into the indicated mean effective pressure Pi (the pressure value obtained by dividing the work calculated based on the finger pressure diagram of the engine 10 by the stroke volume). Here, the magnitude of torque is expressed using the indicated mean effective pressure Pi.

In the present embodiment, not only the moment of force generated in the engine 10 but also the torque equivalent expressed by the average effective pressure (for example, the indicated average effective pressure Pi and the net average effective pressure Pe) acting on the piston 16 of the engine 10. The amount (pressure corresponding to torque) is also referred to as “torque” for convenience. The value of the target torque Pi _TGT calculated here is transmitted to the target flow rate calculation unit 32 and the valve lift control unit 4.
Various specific methods for calculating the target torque Pi _TGT are conceivable. For example, the target torque Pi _TGT is calculated based on an external request required from an electronic control device (for example, CVT-ECU, ESC-ECU, air conditioner ECU, etc.) other than the engine ECU 1 (not shown), a request from the power steering device, etc. May be.

The target flow rate calculation unit 32 calculates a fresh air target flow rate Q _TGT necessary for generating the target torque Pi _TGT calculated by the target torque calculation unit 31. Here, the in-cylinder air amount corresponding to the target torque Pi _TGT is calculated, and the fresh air target flow rate Q _TGT, which is the target value of the air amount to be passed through the throttle valve 7 in order to obtain the in-cylinder air amount, is calculated. Is done. The value of the target flow rate Q _TGT calculated here is transmitted to the normal time opening degree setting unit 35.

The actual torque calculation unit 33 calculates torque (actual torque) generated in the engine 10. Here, the charging efficiency Ec is calculated based on the intake air flow rate Q _IN detected by the air flow sensor 25, and the shaft torque Fm of the engine 10 is calculated based on the charging efficiency Ec and the engine speed Ne. Furthermore, the shaft torque Fm is corrected based on the intake manifold pressure P _A and the atmospheric pressure P _B, the actual torque M is calculated. The value of the actual torque M calculated here is transmitted to the normal time opening degree setting unit 35.
Note that the charging efficiency Ec means the volume of air filled in the cylinder during one intake stroke (one stroke until the piston 16 moves from the top dead center to the bottom dead center). Normalized to volume and then divided by cylinder volume. The value of the charging efficiency and Ec in order to respond to the amount of air introduced into the cylinder at its stroke may be calculated using, for example, only the intake air flow rate Q _IN.

Flow rate calculation unit 34 is for calculating a flow velocity V of the air passing through the throttle valve 7 on the basis of the intake manifold pressure P _A and the atmospheric pressure P _B. In general, the flow rate of a compressible fluid (fluid whose density changes according to pressure change) flowing through the throttle in the pipe is correlated with the pressure ratio before and after the throttle (ratio of downstream pressure to upstream pressure). The flow velocity calculator 34 calculates the flow velocity V using such a correlation. The value of the flow velocity V calculated here is transmitted to the normal time opening degree setting unit 35.

The normal-time opening setting unit 35 includes a fail flag F set by the sensor failure determination unit 2, a target flow rate Q _TGT calculated by the target flow rate calculation unit 32, an actual torque M and a flow velocity calculated by the actual torque calculation unit 33. Based on the flow velocity V calculated by the calculation unit 34, the first target opening degree θ _TH1 of the throttle valve 7 is calculated. Here, when the fail flag F is F = 0, a value obtained by dividing the target flow rate Q _TGT by the flow velocity V is calculated as the target opening area S of the throttle valve 7. Thereafter, the throttle opening at which the flow path cross-sectional area of the throttle valve 7 becomes the target opening area S is calculated as the first target opening θ _TH1 .

Note that the calculation of the first target opening theta _TH1, the detection information of the sensor to be determined in the intake flow rate Q _IN and the intake manifold pressure P _A such sensor failure determination unit 2 is used. Therefore, the first target opening degree θ _TH1 calculated when the fail flag F is F = 0 is highly reliable. On the other hand, when the fail flag F is F = 1, the reliability of the first target opening _θTH1 is lowered. Therefore, the fail flag F is in the case of F = 1 calculates as a first target opening theta _TH1 neat present calculation cycle a first target opening theta _TH1 calculated in the previous computation cycle. That is, as long as the fail flag F does not become F = 0, the first target opening degree θ _TH1 does not change. The value of the first target opening θ _TH1 calculated here is transmitted to the opening controller 3c.

The second target opening setting unit 3b (throttle setting means) is provided with a failure opening setting unit 36 as shown in FIG. The fail-time opening setting unit 36 sets the second target opening θ _TH2 based on the accelerator opening θ _AC . Here, the second target opening θ _TH2 is set as a function of the accelerator opening θ _AC . However, the magnitude of the second target opening θ _TH2 is a value equal to or smaller than the first target opening θ _TH1 . The second target opening θ _TH2 may be further corrected using the accelerator pedal depression speed (change gradient of the accelerator opening θ _AC ) and the engine speed Ne. The value of the second target opening θ _TH2 set here is transmitted to the opening controller 3c.

The opening degree control unit 3c (second tailing control means, throttle control means) outputs a control signal to the throttle valve 7 based on the first target opening degree _θTH1 and the second target opening degree _θTH2 . Here, the target throttle opening degree θ _{TH_TGT} is set according to the following formula 1.
θ _{TH_TGT} = (1-K) · θ _TH1 + K · θ _TH2 (Formula 1)

In Equation 1, K is a tailing coefficient for gradual fluctuation of the target throttle opening θ _{TH_TGT} when the fail flag F changes. The tailing means a continuous and gradual change over a predetermined time. For example, the tailing coefficient K is set as a variable having a domain of 0 or more and 1 or less. Further, it is assumed that the characteristic gradually increases when the fail flag F is 1 and gradually decreases when the fail flag F is 0. Thus, the tailing coefficient K increases to 1 over a predetermined time from the time when the fail flag F changes to 1, and decreases to 0 over a predetermined time from the time when the fail flag F changes to 0.

As described above, the control for smoothing the switching operation when the throttle opening _θTH is switched at the time of the sensor failure is referred to as second tailing control. In the second tailing control, the target throttle opening θ _{TH_TGT} is controlled so as to gradually change from the first target opening θ _TH1 to the second target opening θ _TH2 .

Since the second term on the right side of Equation 1 is 0 when the sensor is not _failing, the target throttle opening θ _{TH_TGT} when not _failing is the first target opening θ _TH1 . In the transient state immediately after the sensor failure is detected, the first term on the right side of Equation 1 gradually decreases while the second term gradually increases. _Therefore , the target throttle opening θ _{TH_TGT} is set to the first target opening. The tailing changes from the degree θ _TH1 to the second target opening θ _TH2 . After the tailing coefficient K becomes 1 at the time of sensor failure, the first term on the right side of Equation 1 becomes 0, and the target throttle opening θ _{TH_TGT} becomes the second target opening θ _TH2 .
Further, the opening control unit 3c, as the actual throttle opening theta _TH approaches the target throttle opening theta _{TH_TGT,} outputs a control signal of the throttle valve 7 (e.g., control voltage).

[2-3. Valve lift control unit]
The valve lift control unit 4 adjusts the intake air amount by controlling the control angle θ _VVL . Here, a first target control angle setting unit 4a that sets a first target control angle θ _VVL1 that is a target value of the control angle θ _VVL at the time of non-failure, and a first value that is a target value of the control angle θ _VVL at the time of failure. A second target control angle setting unit 4b for setting the two target control angle θ _VVL2 and a lift amount control unit 4c are provided.

The first target control angle setting unit 4a (valve lift control means) is provided with a normal valve lift amount setting unit 41 as shown in FIG. The normal valve lift amount setting unit 41 corresponds to the target valve lift amount of the intake valve 8 based on the target torque Pi _TGT calculated by the target torque calculation unit 31 of the throttle control unit 3 and the engine speed Ne. One target control angle θ _VVL1 (first target amount) is set. The specific method for setting the first target control angle θ _VVL1 is arbitrary. For example, the first target control angle θ _VVL1 is set based on the torque exclusively for valve lift control calculated separately from the target torque Pi _TGT. Alternatively, a correction calculation using the intake air flow rate Q _IN , the intake manifold pressure P _A , the atmospheric pressure P _B , the cooling water temperature W, or the like may be added thereto.

As shown in FIG. 2D, the second target control angle setting unit 4b (valve lift setting means) is provided with a valve lift amount setting unit 42 at the time of failure. The valve lift amount setting unit 42 at the time of failure uses, as a second target control angle θ _VVL2 (second target amount) corresponding to the target valve lift amount, a value preset as a reference value of the valve lift amount used at the time of sensor failure. It is to set. The second target control angle θ _VVL2 is a control angle θ _VVL that _maximizes the engine torque at the same throttle opening θ _TH .

Here, FIG. 3 illustrates the relationship between the throttle opening θ _TH and the control angle θ _VVL (valve lift amount) when a certain amount of air is introduced into the cylinder 14. Here, six types of graphs in which the phase angle θ _VVT (valve timing) is different for each of the three engine speeds Ne are displayed in an overlapping manner. Assuming that the engine speed Ne is Ne ₁ > Ne ₂ > Ne ₃ , graphs A and B are graphs E and B when the engine speed Ne is Ne ₁ , and graphs C and D are graph E when the engine speed Ne is Ne _2. , F indicates the case where the engine speed Ne is Ne ₃ . A graph A, C, E if the phase angle theta _VVT of theta _VVT1, graph B, D, F denotes a case where the phase angle theta _VVT of theta _VVT2.

Since the vertical axis of the graph is the throttle opening θ _TH required to secure a predetermined intake air amount at the control angle θ _VVL , the smaller the vertical axis value (the lower the graph is), It means that air can easily enter the cylinder 14 (high intake performance). Therefore, air is most likely to enter in the state of graph A when the control angle θ _VVL is θ _{VVL_A} . On the other hand, air is most likely to enter in the state of graph B when the control angle θ _VVL is θ _{VVL_B} .

That is, even if the engine speed Ne and the target intake air amount are the same, if the phase angle θ _VVT is different, the control angle θ _{VVL at} which the air enters the cylinder 14 is a different value. Similarly, as shown in graphs D and F, even if the phase angle θ _VVT and the target intake air amount are constant, if the engine speed Ne is different, the control angle θ that provides the highest air introduction efficiency. _VVL is different. Based on such characteristics, the second target control angle setting unit 4b controls the control angle θ _VVL that allows air to enter most easily, that is, the control angle corresponding to the lift amount at which the engine torque becomes _maximum at the same throttle opening θ _TH. θ _VVL is set as the second target control angle θ _VVL2 .

In the present embodiment, the value of the second target control angle θ _VVL2 is preset as a function, map, or table of the engine speed Ne and the phase angle θ _VVT . The second target control angle setting unit 4b sets the second target control angle θ _VVL2 based on the engine speed Ne and the phase angle θ _VVT using such a correspondence. The method for setting the second target control angle θ _VVL2 is not limited to this, and may be set only according to the engine speed Ne, or may be set only according to the phase angle θ _VVT . Further, the second target control angle θ _VVL2 may be set using other parameters such as the charging efficiency Ec and the intake air flow rate Q _IN together. Alternatively, the second target control angle θ _VVL2 may be set as a fixed value between θ _{VVL_A} and θ _{VVL_B} .

The graph of FIG. 3 is a graph plotting the throttle opening θ _TH when the control angle θ _VVL is changed in four stages, and the horizontal axis coordinate of the minimum point of the graph is any one of the four control angles θ _VVL. Become. On the other hand, if the control angle θ _VVL is changed in more stages and the same test is performed, a graph with a slightly smoother shape than the graph of FIG. 3 can be obtained, and the horizontal axis coordinate of the minimum point may change. is there. Conversely, the same applies when the test is performed with the number of steps for changing the control angle θ _VVL being reduced, and the minimum point of the graph may be located in the middle between θ _{VVL_A} and θ _{VVL_B} . Therefore, the value of the second target control angle θ _VVL2 can be set according to the control resolution of the control angle θ _VVL by the variable valve lift mechanism 6a.

The lift amount control unit 4c (first tailing control means, valve lift control means) outputs a control signal to the variable valve lift mechanism 6a based on the first target control angle θ _VVL1 and the second target control angle θ _VVL2. It is. Here, the target control angle θ _{VVL_TGT} is set according to the following equation 2.
θ _{VVL_TGT} = (1-K) · θ _VVL1 + K · θ _VVL2 (Equation 2)

The tailing coefficient K in Equation 2 is the same as that in Equation 1. Therefore, the target control angle θ _{VVL_TGT} when the sensor is not _failing becomes the first target control angle θ _VVL1 , and in the transient state immediately after the sensor failure is detected, the target control angle θ _{VVL_TGT} is changed from the first target control angle θ _VVL1. The tailing changes to the second target control angle θ _VVL2 . In addition, after the sensor failure is detected and the tailing coefficient K becomes 1, the target control angle θ _{VVL_TGT} becomes the second target control angle θ _VVL2 .

Further, the lift amount control unit 4c outputs a control signal to the variable valve lift mechanism 6a so that the actual control angle θ _VVL approaches the target control angle θ _{VVL_TGT} .
Thus, the control for smoothing the switching operation when the valve lift amount is switched at the time of the sensor failure is referred to as first tailing control. In the first tailing control, the target control angle θ _{VVL_TGT} is controlled so as to gradually change from the first target control angle θ _VVL1 to the second target control angle θ _VVL2 .

[3. flowchart]
FIG. 4 is a flowchart illustrating a control procedure executed by the engine ECU 1. Here, a flow for controlling the throttle opening θ _TH of the throttle valve 7 and the control angle θ _VVL of the variable valve lift mechanism 6a will be described.

In step A10, detection information of various sensors is read into the engine ECU1. The types of information input here are, for example, accelerator opening θ _AC , engine speed Ne, intake air flow rate Q _IN , intake manifold pressure P _A , atmospheric pressure P _B , cooling water temperature W, and the like. Further, the phase angle θ _VVT of the variable valve timing mechanism 6 b is also transmitted to the engine ECU 1.
In step A20, the first target opening setting portion 3a, the first target opening theta _TH1 of the throttle opening theta _TH based on detection information from various sensors are set. The first target opening θ _TH1 set here is a value in consideration of the target torque Pi _TGT , the actual torque M, and the like of the engine 10.

On the other hand, in step A30, the second target opening setting unit 3b sets the second target opening θ _TH2 of the throttle opening θ _TH based on the accelerator operation amount θ _AC . The second target opening degree θ _TH2 set here is a value given without using detection information from the sensor to be determined by the sensor failure determination unit 2.
In Step A40, the first target control angle setting unit 4a sets the first target control angle θ _VVL1 of the control angle θ _VVL of the variable valve lift mechanism 6a based on the detection information of various sensors. The first target control angle θ _VVL1 set here is a value that takes into account the target torque Pi _{TGT and the} like.

On the other hand, in step A50, the second target control angle setting unit 4b sets the second target control angle θ _VVL2 of the control angle θ _VVL based on the engine speed Ne and the valve phase angle θ _VVT . The second target control angle θ _VVL2 set here is a value given without using detection information from the sensor to be determined by the sensor failure determination unit 2.
In subsequent step A60, the sensor failure determination unit 2 determines the sensor failure. Here, the failure of each of the air flow sensor 25, the intake manifold pressure sensor 26, the atmospheric pressure sensor 27, and the water temperature sensor 28 is determined, and if at least one of the sensors is in a failure state, the failure flag F is set to F = 1. Then, control proceeds to step A70. On the other hand, if all the sensors are not in the fail state, the fail flag F is set to F = 0, and the control proceeds to step A80.

  Steps A70 to A84 are steps relating to the setting of the tailing coefficient K. First, in step A70 which proceeds when the fail flag F is F = 1, a predetermined tailing gain G is added to the tailing coefficient K. The tailing gain G is a value corresponding to the increase / decrease width of the tailing coefficient K for each control cycle, and may be a fixed value set in advance, or set based on the detection information of various sensors read in step A10. Also good.

  In subsequent step A72, it is determined whether or not the tailing coefficient K is 1 or less. If K> 1, the process proceeds to step A74, K = 1 is set, and the process proceeds to step A90. On the other hand, if K ≦ 1, the process proceeds directly to step A90. Since the upper limit value of the tailing coefficient K is limited to 1 through steps A72 and A74, as long as the fail flag F is F = 1, the subsequent tailing coefficient K is maintained at K = 1.

  Further, in step A80 which proceeds when the fail flag F is F = 0, a predetermined tailing gain G is subtracted from the tailing coefficient K. In step A82, it is determined whether the tailing coefficient K is 0 or more. If K <0, the process proceeds to step A84, K = 0 is set, and the process proceeds to step A90. On the other hand, if K ≧ 0, the process proceeds to step A90. Since the lower limit value of the tailing coefficient K is limited to 0 through steps A82 and A84, the subsequent tailing coefficient K is maintained at K = 0 as long as the fail flag F is F = 0.

In step A90, the target throttle opening θ _{TH_TGT} is set in accordance with the expression 1 in the opening control unit 3c. Similarly, in step A100, the lift control unit 4c sets the target control angle θ _{VVL_TGT} according to Equation 2. Thereafter, in step A110, the control signal from the opening control unit 3c to the throttle valve 7 is outputted, control is performed such that the actual throttle opening theta _TH approaches the target throttle opening degree θ _{TH_TGT.} Further, a control signal is output from the lift amount control unit 4c to the variable valve lift mechanism 6a, and control is performed so that the actual control angle θ _VVL approaches the target control angle θ _{VVL_TGT} .

[4. Action]
[4-1. Control of throttle opening]
The control action by this control apparatus will be described. The broken line graph in FIG. 5A shows the variation of the first target opening θ _TH1 set by the first target opening setting unit 3a of the throttle control unit 3, and the alternate long and short dash line graph shows the second target opening setting unit. The variation of the second target opening θ _TH2 set in 3b is shown, and the thick solid line shows the variation of the target throttle opening θ _{TH_TGT} calculated by the opening control unit 3c.

When the driver starts depressing the accelerator pedal at time t ₀ , the accelerator opening θ _AC gradually increases and the target torque Pi _TGT also increases. At this time, it is assumed that the fail flag F is F = 0, and the value of the tailing coefficient K is the initial value 0.
In response to an increase in the target torque Pi _TGT, when the first target opening theta _TH1 is increased to be set at the first target opening setting portion 3a at time t ₀ after the target throttle opening theta _{TH_TGT} increases. Further, since the second target opening θ _TH2 set by the second target opening setting unit 3b is also set as a function of the accelerator opening θ _AC , it increases after time t ₀ . Note that the second target opening theta _TH2 is set in a range of the first target opening theta _TH1, in FIG. 5 (a) the second target opening theta downward than the first target opening theta _{TH1 The TH2} graph is located.

When the sensor failure occurs at time t ₁ is in the depression of the accelerator pedal, as shown in FIG. 5 (b), the fail flag F is set to F = 1. From this point, the tailing coefficient K starts to gradually increase from zero. As shown in FIG. 5 (a), the value of the first target opening theta _TH1 when the first target opening degree setting unit 3a at time t ₁ is held. On the other hand, the second target opening theta _TH2 with the second target opening setting portion 3b in an increase of the accelerator opening theta _AC is set to increase. Thus, the target throttle opening θ _{TH_TGT obtained} by interpolating between the first target opening θ _TH1 and the second target opening θ _TH2 is set by the opening control unit 3c. Even if the difference between the first target opening theta _TH1 and the second target opening theta _TH2 is wide open at time t _1, the target throttle opening theta _{TH_TGT} moderately from the first target opening theta _TH1 to vary so as to approach to the second target opening theta _TH2, sudden change in torque due to the throttle opening change is suppressed.

At time t ₂ when the tailing factor K is 1, the target throttle opening theta _{TH_TGT} matches the second target opening theta _TH2, tailing control is completed. The time from the time t ₁ to the time t ₂ (for example, several seconds) can be adjusted by changing the magnitude of the tailing gain G. Further, the target throttle opening θ _{TH_TGT} after time t ₂ has the same value as the second target opening θ _TH2 set according to the accelerator opening θ _AC .

When sensor failure by the sensor failure determining portion 2 at time t ₃ is not detected, the tailing factor K starts to gradually decrease from 1. In the opening degree control unit 3c, the target throttle opening degree θ _{TH_TGT} is set so as to approach gradually from the second target opening degree θ _TH2 to the first target opening degree θ _TH1 , so that a sudden change in torque accompanying a change in the throttle opening degree Is suppressed. At time t ₄ when tailing coefficient K is 0, the target throttle opening theta _{TH_TGT} matches the first target opening theta _TH1, tailing control is completed.

In the normal-time opening setting unit 35 of the above-described embodiment, when the fail flag F is F = 1, the first target opening _θTH1 calculated in the previous calculation cycle is used as it is in the current calculation cycle. Although calculated as a target opening theta _TH1, the variation of the first target opening theta _TH1 in the case of omitting the carry-over operation of such calculated values, the time t ₁ ~t ₃ in FIG. 5 (a) Is indicated by a thin solid line. Since this calculated value is not necessarily a value calculated based on accurate detection information, it is preferably not used for the interpolation calculation of the target throttle opening θ _{TH_TGT} .

[4-2. Control of valve lift]
In the present control device, the valve lift amount is controlled in parallel with the throttle opening control. For example, as indicated by a solid line in FIG. _5C , the value of the first target control angle θ _VVL1 set by the first target control angle setting unit 4a before time t ₁ is a predetermined value θ _{VVL_C.} . When the sensor failure at time t ₁ is generated, tailing coefficient K begins to gradually increase from 0, the target control angle theta _{VVL_TGT} interpolated between the first target control angle theta _VVL1 the second target control angle theta _VVL2 lift It is set by the quantity control unit 4c.

The target control angle θ _{VVL_TGT} changes so as to gradually approach the second target control angle θ _VVL2 from the first target control angle θ _VVL1 , and a sudden change in torque accompanying a change in the valve lift amount is suppressed. Since the tailing coefficient K related to the calculation in the valve lift control unit 4 is the same as the tailing coefficient K related to the calculation in the throttle control unit 3, the time (tailing time) related to tailing control of the valve lift amount is It coincides with the time for tailing control of the target throttle opening.

The second target control angle θ _VVL2 set by the second target control angle setting unit 4b is a control angle θ _VVL corresponding to the lift amount at which the engine torque becomes _maximum at the same throttle opening θ _TH . That is, the control angle θ _VVL is such that air is most likely to enter the cylinder 14 in the operating state of the engine 10 at that time. Accordingly, as indicated by hatching in FIG. 5 (d), the engine torque financed by controlling the valve lift amount is monotonously increased from the time t ₁ to time t _2.

As indicated by the alternate long and _short dash line in FIG. _5C , the value of the first target control angle θ _VVL1 before time t ₁ is temporarily smaller than the second target control angle θ _VVL2 (for example, a predetermined value θ _{VVL_D} ), The change direction of the valve lift between the times t _{1 and} t ₂ is always the direction in which air can easily enter. Therefore, the engine torque provided by the control of the valve lift amount between times t ₁ and t ₂ always increases monotonously regardless of the value of the immediately preceding control angle θ _VVL .

On the other hand, in the control of the target throttle opening, the second target opening θ _TH2 is set in a range equal to or smaller than the first target opening θ _TH1 . Therefore, the ratio of the engine torque provided by controlling the throttle opening with respect to the entire engine torque tends to decrease as shown in FIG. In other words, focusing on the engine torque during tailing control, the control angle θ _VVL is controlled in a direction that monotonously increases the engine torque, while the throttle opening θ _TH is controlled in a direction that monotonously decreases the engine torque. The As a result, a change in engine torque during tailing control becomes a monotonous change, and a situation in which the torque fluctuation direction is reversed in the middle is prevented.

In addition, the target control angle θ _{VVL_TGT} has the same value as the second target control angle θ _VVL2 from time t ₂ to time t ₃ when the tailing coefficient K is 1. That is, during the sensor failure, the valve lift amount is controlled so that the air introduction efficiency is increased. When the non-fail state is entered at time t ₃ and the tailing coefficient K starts to gradually decrease from 1, the lift control unit 4c _changes the target control angle θ _{VVL_TGT} from the second target control angle θ _VVL2 to the first target control angle θ _VVL1. It is set to approach slowly. As a result, the tailing control is terminated while the sudden change in torque accompanying the change in the valve lift amount is suppressed.

[5. effect]
[5-1. Throttle control]
In the torque-based control, when the sensors such as the air flow sensor 25, the intake manifold pressure sensor 26, the atmospheric pressure sensor 27, and the water temperature sensor 28 fail, the actual torque calculation (estimation calculation), the flow velocity V of the air passing through the throttle valve 7, the idle It becomes difficult to calculate the load and the like, and it becomes difficult to accurately set the target opening of the throttle valve and the valve lift amount.

The amount of air actually introduced into the cylinder 14 is not only the phase angle θ _VVT of the variable valve timing mechanism 6b and the control angle θ _VVL of the variable valve lift mechanism, but also the pressure in the intake passage and the throttle opening θ _TH. Fluctuates depending on Therefore, in throttle control not using this control device, even if a value for failure is set in advance as the control amount of the variable valve mechanism 6, the engine torque may become unstable, and the vehicle behavior is stabilized. May not be able to secure the sex.

On the other hand, in the control device for the engine 10 described above, the throttle control unit 3 sets the second target opening θ _TH2 at the time of failure based on the accelerator opening θ _AC . In this way, by setting the opening without using sensors such as the airflow sensor 25, the intake manifold pressure sensor 26, the atmospheric pressure sensor 27, and the water temperature sensor 28, the throttle valve 7 can be controlled even during a failure. It becomes. Also, with this arrangement varying the throttle opening theta _TH with a tailing the failure time, it is possible to smoothly change the engine torque, it is possible to suppress the torque fluctuation and the torque shock due to this.
Further, since the second target opening θ _TH2 that is the target value after the failure is set within the range of the first target opening θ _TH1 that is the target value before the failure, the fluctuation of the engine torque due to the fail control, that is, In addition, the fluctuation of the engine torque covered by the control of the throttle opening θ _TH can be monotonously reduced.

The magnitude of the engine torque generated in the engine 10 is not determined only by the throttle opening θ _TH , but the target torque Pi _TGT , the external required torque, the engine speed Ne, the control angle θ _VVL , the phase angle θ _VVT, etc. The value is determined by various conditions. Therefore, even if the engine torque provided by controlling the throttle opening θ _TH is reduced, the overall engine torque is not necessarily reduced.
However, in the present control device, it is possible to reduce the torque fluctuation depending on at least the throttle opening _θTH . In other words, a decreasing tendency can be given in the direction of change of the engine torque, and the engine torque can be easily stabilized.

[5-2. Valve lift control]
As described above, the intake air amount introduced into the cylinder 14 through the intake valve 8 is not necessarily proportional to the valve lift amount. Therefore, in valve lift control that does not depend on this control device, even if the valve lift amount is gradually increased, the intake air amount does not increase monotonously with respect to the change in the valve lift amount, and a certain valve lift amount is bounded. As the direction of decrease. That is, since the change direction of the valve lift amount and the change direction of the intake air amount do not necessarily match, an unnecessary increase / decrease change may occur in the intake air amount in the process of changing the valve lift amount. As a result, unintended vehicle behavior may occur.

On the other hand, the second target control angle θ _VVL2 set by the second target control angle setting unit 4b of the present control device is the control angle θ _VVL that _maximizes the engine torque at the same throttle opening θ _TH. The intake air amount can be monotonously increased with respect to the change in the valve lift amount. That is, the change direction of the valve lift amount and the change direction of the intake air amount can be matched, and the engine is covered by the fluctuation of the engine torque by the first tailing control, that is, the control of the control angle θ _VVL related to the valve lift amount. The torque fluctuation can be monotonously increased.

As a result, it is possible to prevent a situation in which the torque fluctuation direction is reversed in the middle (for example, torque fluctuation that increases and then decreases), and it is possible to easily stabilize the vehicle behavior. In addition, since the engine torque generated at the second target control angle θ _VVL2 is greater than the engine torque generated at the first target control angle θ _VVL1 , intake performance (intake air) to the cylinder 14 at the time of sensor failure is obtained. Can be secured.

[5-3. Compound control]
Further, in the present control device, the second tailing control related to the throttle opening θ _TH and the first tailing control related to the valve lift amount are simultaneously performed with the same tailing time. Thus, the decrease in engine torque due to the control of the throttle opening _θTH can be compensated by the increase in engine torque due to the control of the valve lift amount. Although the decrease amount and the increase amount of the engine torque are not necessarily the same value, the change amount of the engine torque becomes small by adding them together. Thereby, the change of the engine torque before and after the occurrence of the failure can be suppressed, and the vehicle behavior can be further stabilized.

Further, in the present control device, the engine speed Ne is used when setting the second target control angle θ _VVL2 in the second target control angle setting unit 4b. This makes it possible to set the second target control angle θ _VVL2 using the correlation between the engine speed Ne and the engine torque, and accurately grasp the control angle θ _VVL corresponding to the lift amount at which the engine torque becomes the largest. Can do.

Similarly, the second target control angle setting unit 4b sets the second target control angle θ _VVL2 using the phase angle θ _VVT of the variable valve timing mechanism 6b. Thereby, the correlation between the phase angle θ _VVT and the engine torque can also be used, and the control angle θ _VVL corresponding to the lift amount at which the engine torque becomes _maximum can be grasped more accurately.

If the second target control angle θ _VVL2 is set in combination with other parameters such as the charging efficiency Ec and the intake air flow rate Q _IN , the setting accuracy of the control angle θ _VVL can be further improved. Alternatively, if the second target control angle θ _VVL2 is set as a fixed value between θ _{VVL_A} and θ _{VVL_B} , the ROM capacity and calculation load related to the calculation of the second target control angle θ _VVL2 can be reduced. Cost can be reduced.

  In the present control device, the sensor failure determination unit 2 determines each failure of the airflow sensor 25, the intake manifold pressure sensor 26, the atmospheric pressure sensor 27, and the water temperature sensor 28. As a result, it is possible to grasp the failure of the sensor that detects important information in torque-based control and the trouble related to reading, and quickly execute the second tailing control and the first tailing control, based on inaccurate information Throttle control and valve lift control can be prevented.

[6. Modified example]
Regardless of the embodiment described above, various modifications can be made without departing from the spirit of the invention. Each structure of this embodiment can be selected as needed, or may be combined appropriately.
In the above-described embodiment, the example in which tailing is given to the variation of the target throttle opening θ _{TH_TGT} and the target control angle θ _{VVL_TGT} using the formula 1 and the formula 2 is exemplified, but the specific tailing imparting method is limited to this. Not. For example, tailing may be applied by limiting the amount of change per unit time of the target throttle opening θ _{TH_TGT} and the target control angle θ _{VVL_TGT} to a predetermined value or less. The larger the amount of change per unit time, the shorter the tailing time, and the smaller the amount of change, the longer the tailing time.

For the target throttle opening θ _{TH_TGT} , at least start calculation to gradually approach the second target opening θ _TH2 when a sensor failure is detected, and gradually increase to the first target opening θ _TH1 when no sensor failure is detected It is only necessary to start the calculation to approach the target. The same _applies to tailing of the target control angle θ _{VVL_TGT} .
In the above-described embodiment, the tailing time of the target throttle opening θ _{TH_TGT and} the tailing time of the target control angle θ _{VVL_TGT} are exemplified, but the target throttle opening θ using two different tailing coefficients. The tailing time of _{TH_TGT} and target control angle θ _{VVL_TGT} may be individually controlled. At least when there is a _{period in} which the second tailing control related to the target throttle opening θ _{TH_TGT} and the first tailing control related to the target control angle θ _{VVL_TGT} are simultaneously performed at the time of switching between detection and non-detection of sensor failure Good.

In the above-described embodiment, the engine ECU 1 having the functions of the sensor failure determination unit 2, the throttle control unit 3, and the valve lift control unit 4 has been exemplified. However, the specific control configuration of the engine ECU 1 is not limited to this. . The throttle opening θ _TH can be controlled with at least means corresponding to the throttle control unit 3, and the control angle θ _VVL of the variable valve lift mechanism 6 a can be controlled with at least means corresponding to the valve lift control unit 4. That's fine. Therefore, a specific control configuration can be added or simplified as appropriate.

  In the above embodiment, the valve lift amount of the intake valve 8 is exemplified. However, instead of or in addition to this, the valve lift amount of the exhaust valve 9 may be controlled. In addition, the form of the valve operating system of the engine 10 of the above-mentioned embodiment is arbitrary. Any engine having at least a mechanism for making the valve lift variable can be used. For example, an engine without the variable valve timing mechanism 6b may be used.

1 Engine ECU
2 Sensor failure determination unit 3 Throttle control unit 3a First target opening setting unit (throttle control means)
3b Second target opening setting section (throttle setting means)
3c Opening control unit (second tailing control means, throttle control means)
4 Valve lift control unit 4a First target control angle setting unit (valve control means)
4b Second target control angle setting section (valve setting means)
4c Lift amount control unit (first tailing control means, valve control means)
6 Variable valve mechanism 7 Throttle valve 8 Intake valve 10 Engine

Claims (6)

A first target amount as a target lift amount of the intake valve based on detection information of a sensor attached to the engine, and a valve lift control means for controlling the lift amount of the intake valve to the first target amount;
A valve lift setting means for setting, as a second target amount, a lift amount at which the engine torque becomes maximum at the same throttle opening;
An engine control device comprising: first tailing control means for performing first tailing control for gradually changing the lift amount to the second target amount when the sensor fails. A throttle control means for setting the first target opening of the throttle valve based on the detection information of the sensor and controlling the throttle opening to the first target opening;
Throttle setting means for setting a second target opening of the throttle valve based on an accelerator opening within a range of at least the first target opening;
2. The second tailing control means for performing second tailing control for gradually changing the throttle opening to the second target opening at the time of failure of the sensor. Engine control device. The engine control device according to claim 2, wherein the first tailing control means simultaneously performs the first tailing control at the same tailing time as the second tailing control by the second tailing control means. . The engine control device according to any one of claims 1 to 3, wherein the valve lift setting means sets the second target amount based on an engine speed. The engine control device according to any one of claims 1 to 4, wherein the valve lift setting means sets the second target amount based on a valve timing of the intake valve. The engine control device according to any one of claims 1 to 5, wherein the sensor includes at least one of an air flow sensor, an intake manifold pressure sensor, an atmospheric pressure sensor, and a cooling water temperature sensor. .

Images