JPH07189758A - Fuel control device for engine with cylinder deactivation mechanism - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a fuel control device for an engine with a cylinder deactivation mechanism having cylinders that can be deactivated, and at the time of switching from all-cylinder operation to cylinder deactivation operation, it is determined that switching is not completed for one cylinder. It is an object of the present invention to ensure that the engine can perform stable operation at low cost by ensuring that the engine can be reliably operated from the failure. [Configuration] An operation mode setting means A4, a valve variable drive control means A1, a fuel supply control means A3, an air-fuel ratio detection means A7 and an air-fuel ratio feedback control means A8 are provided, and the air-fuel ratio feedback control amount is compared with a predetermined threshold value. Based on the detection results of the means A9 for detecting the sticking state to the rich side limit control and whether or not the switching from the valve non-operating state to the valve operating state is completed based on the detection result of the air-fuel ratio limit control sticking state detecting means A9. And a switching determination means A2 that outputs a switching incompletion signal when it is determined that switching has not been completed, and a required fuel supply means when the switching determination means A2 outputs a switching incompletion signal under the condition that the all cylinder mode is set. F
The fuel supply limiting means A6 that makes S inoperative is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deactivated cylinder having a deactivating cylinder in which at least one of opening and closing of an intake valve and an exhaust valve can be selectively opened and closed by valve operation switching means. The present invention relates to a fuel control device for an engine with a cylinder mechanism.

[0002]

2. Description of the Related Art During operation of an engine (internal combustion engine), a low speed cam or a high speed cam is selectively switched and driven in order to drive an intake / exhaust valve at an opening / closing timing suitable for each engine operating range to improve output. It is known to provide a variable valve drive mechanism capable of performing the above, and use the variable valve drive mechanism to stop intake and fuel supply to some cylinders to reduce output and reduce fuel consumption.

The control means for controlling the valve variable drive mechanism of this type of engine sets each operation mode on the basis of various operation information, and, for example, when the cylinder deactivation mode region is entered, the suction cylinders of the cylinder deactivated cylinder are operated in that mode. The opening / closing operation of the exhaust valve is stopped and the fuel supply to the cylinder deactivated is stopped. When the cylinder deactivation mode is exited, the opening / closing operation of the intake / exhaust valves of the cylinder deactivated is returned to the normal state, and the fuel supply to the cylinder deactivated is restarted.
Furthermore, even in all-cylinder operation, the low speed cam is used to drive the intake and exhaust valves in the low speed mode to improve the volumetric efficiency at low speed,
In high speed mode, drive the intake and exhaust valves using the high speed cam,
It is configured to improve the volumetric efficiency at high speed and to improve the output in each engine operating state.

In order to perform such partial cylinder operation,
A variable valve drive mechanism is known in which the opening / closing operation of the intake / exhaust valve is disabled by, for example, a lock pin driven by operating hydraulic pressure, and the intake / exhaust valve of a specific cylinder is maintained in a closed state to stop the opening / closing operation. There is. In this variable valve drive mechanism, the intake / exhaust valve is normally opened / closed without operating the operating oil pressure, and the operating oil pressure is operated during the partial cylinder operation to drive the lock pin to operate the intake valve and the exhaust valve. Operates to be in a normally closed state.

By the way, the variable valve drive control means for controlling the variable valve drive mechanism of the engine must be able to quickly switch the valve operating system and the fuel supply system to the respective operating modes set based on various operating information of the engine. is there. That is, there is no problem if the variable valve drive mechanism in the valve train is driven by an electromagnetic valve or a hydraulic circuit that can be switched to the valve, and the various switching actuating members complete the switching at a predetermined timing.

However, each switching operation member may cause switching failure due to deterioration over time.
Particularly, when the operation state in the cylinder deactivation mode is switched to the operation in the all cylinder mode, the opening / closing operation of the intake / exhaust valve of the cylinder deactivation cylinder is immediately restarted. When the malfunction occurs, the valve operating system may continue to operate in the cylinder deactivation mode even though the variable valve drive control means continues to control in the all cylinder mode.

In such a case, a sensor for directly detecting the operating state of the valve is required, but this has not been put into practical use. Here, in the case like above,
When the valve train is operated in the cylinder deactivation mode and the fuel supply system is operated in the all cylinders mode, and fuel is continuously supplied to all cylinders, the fuel supplied to the cylinders deactivated is passed through the surge tank. Flow into the normally operating cylinder side, which may cause a gasoline hammer phenomenon in the cylinder.

Therefore, conventionally, for example, Japanese Patent Laid-Open No. 60-139.
An engine having a failure countermeasure device as disclosed in Japanese Patent No. 29 has been proposed. In this conventional technique, in order to detect an abnormality (failure) in the intake / exhaust valve opening / closing operation stopping means,
A position sensor that can detect the amount of movement of the operating rod that constitutes the intake / exhaust valve opening / closing operation stop means is provided, and an abnormality (fault) in the intake / exhaust valve opening / closing operation stop means is detected based on the detection result of this position sensor. Failure countermeasures are taken according to the detection result.

[0009]

However, in such a conventional technique, an expensive position sensor is separately required to detect an abnormality (failure) in the intake / exhaust valve opening / closing operation stopping means, which causes an increase in cost. Therefore, it is difficult to adopt. Further, by comparing the negative pressure value in all cylinders corresponding to the engine speed and throttle opening with the current intake pipe negative pressure, it is determined whether or not the valve train has completed switching to the all cylinder mode, A technique for controlling the fuel supply means to be driven in the cylinder deactivation mode when the switching is not completed has been considered.

As shown in FIG. 12, this is to judge one cylinder failure and two cylinder failure by comparing the intake pipe negative pressure with the throttle opening on the horizontal axis as compared with the normal time. However, there is a problem that such a means can detect the fail state of two cylinders in a four-cylinder engine, but it is difficult to detect the fail state of one cylinder.

That is, FIG. 13 shows a detection operating region characteristic in which the intake pipe negative pressure can be utilized to detect the failure state of the cylinder based on the above-described principle. It shows the characteristics that can be taken in each operating condition by taking the intake pipe negative pressure. Here, the uppermost characteristic shows the three-cylinder full-open operation characteristic, the second characteristic shows the two-cylinder fully-open operation characteristic, the right-down diagonally shaded area shows the area that can be taken by the single-cylinder fail operation, and the right-upward diagonally shaded area shows The region which can be taken by the cylinder fail operation is shown.

As shown by this characteristic, the one-cylinder fail region is a small region included in the two-cylinder fail region,
There is a problem that the fail state cannot be reliably detected from a single-cylinder fail. The present invention has been devised in view of such a problem, and when switching from all-cylinder operation to in-cylinder operation, it is possible to reliably determine that switching has not been completed from the failure of one cylinder, and the engine is stable. It is possible to realize the control that can perform the driving at low cost.
An object of the present invention is to provide a fuel control device for an engine with a cylinder deactivation mechanism.

[0013]

Therefore, in the fuel control system for an engine with a cylinder deactivation mechanism according to the present invention, at least one of the intake valve and the exhaust valve is opened and closed by the valve operation switching means. In an engine with a cylinder deactivation mechanism that has a cylinder that can be paused that can be selectively switched with and
By the operation mode setting means for setting either the all cylinder mode that does not stop the cylinders that can be deactivated or the cylinder deactivation mode that deactivates the predetermined cylinders as the target operation mode according to the operating state information of the engine, and the operation mode setting means. A valve variable drive control means for controlling the valve operation switching means so as to be in an operating state corresponding to the set target mode,
Corresponding to the target operation mode set by the operation mode setting means, the fuel supply means associated with the restable cylinder is operated in the all cylinder mode, and the fuel supply means associated with a predetermined restable cylinder in the cylinder deactivated mode. With a fuel supply control means for deactivating, an air-fuel ratio detecting means for detecting the air-fuel ratio of the engine, and for supplying fuel to the engine using the air-fuel ratio detected by the air-fuel ratio detecting means. An air-fuel ratio feedback control means for performing feedback control, and an air-fuel ratio limit control sticking state detection means for detecting a sticking state to the rich side limit control by comparing the feedback control amount by the air-fuel ratio feedback control means with a predetermined threshold value. Provided, the switching from the valve non-operating state to the valve operating state by the operation of the valve variable drive control means is completed. It is determined whether or not the switching is incomplete based on the detection result of the air-fuel ratio limit control sticking state detection means, and if the switching incompletion is output, the switching determination means that outputs the switching incompletion signal and the operation mode setting means are in the all cylinder mode. When the switching determination means outputs the switching incompletion signal under the condition that the above condition is set, the fuel supply limiting means for deactivating the required fuel supply means is provided.

[0014]

In the fuel control device for an engine with a cylinder deactivation mechanism of the present invention described above, either the all cylinder mode in which the cylinders that can be deactivated or the cylinder deactivation mode that deactivates a predetermined cylinder is deactivated by the operation mode setting means. The target operation mode is set in accordance with the operating state information of. Then, at least one of the intake valve and the exhaust valve is selectively opened / closed by valve operation switching so that the valve variable drive control means is brought into an operating state corresponding to the target mode set by the operation mode setting means. Then, the operating state and the non-operating state are switched. Then, the fuel supply control means activates the fuel supply means associated with the restable cylinders in the all-cylinder mode, and deactivates the fuel supply means associated with a predetermined restable cylinder in the cylinder deactivation mode. Further, feedback control for fuel supply to the engine by the air-fuel ratio feedback control means is performed using the operating air-fuel ratio of the engine detected by the air-fuel ratio detection means. And
When switching from the valve non-operating state to the valve operating state by the operation of the variable valve drive control means, whether or not the switching is completed is detected by comparing the feedback control amount by the air-fuel ratio feedback control means with a predetermined threshold value. When it is judged based on the detection result of the state of sticking to the rich side limit control and it is judged that the switching is not completed, the switching incompletion signal is output from the switching judgment means, and the same output is set in the all cylinder mode. Under such a situation, the fuel supply restriction means deactivates the required fuel supply means.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel control device for an engine with a cylinder deactivation mechanism as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing its control system, and FIG. 3 and 4 are characteristic diagrams showing control characteristics of the device, FIGS. 5 to 9 are flowcharts showing control procedures thereof, and FIGS. 10 and 11 are diagrams showing control characteristics thereof. is there.

An engine system for an automobile to which the apparatus of this embodiment is applied is constructed as shown in FIG. 2, and is mounted on a fuel injection engine 1 using DOHC in-line 4-cylinder gasoline fuel. ing. This engine 1
Of the intake manifold IR is connected to one end of an intake manifold IM that can communicate with each cylinder, and a surge tank 37 is attached to the other end of the intake manifold IM to form an intake passage IR. Further, it has an intake pipe communicating with the surge tank 37, an air cleaner 38, and the like.

On the other side of the cylinder head 2, an exhaust manifold EM capable of communicating with each cylinder is attached,
An exhaust passage ER including an exhaust pipe is connected to the exhaust manifold EM. A throttle valve 40 is disposed downstream of the air cleaner 38 in the intake passage IR, and a rotary shaft 41 of the throttle valve 40 is configured to be rotated by a valve drive actuator 42 having a stepper motor. There is.

The valve drive actuator 42 is connected to an engine control unit (ECU) 32 described later,
It is configured to perform a desired rotation by a predetermined control signal. Further, the throttle valve 40 is supplied with a throttle opening signal θs corresponding to the throttle opening.
A throttle opening sensor 36 for outputting to the CU 32 is attached.

Further, a negative pressure sensor 35 for outputting a negative pressure signal Pb corresponding to the negative pressure of the intake pipe is mounted on the surge tank 37 of the intake passage IR. An example of data detected by the negative pressure sensor 35 is shown in FIGS. 4 (a) and 4 (b). Here, FIG. 4A is a Pb-θs diagram when the engine speed Ne is idle, and FIG. 4B is the engine speed N.
FIG. 3 is a Pb-θs diagram when e is 3000 rpm, in which the broken line shows the cylinder inactive and the solid line shows the cylinder in full.

An intake port (not shown) of each cylinder is opened and closed by an intake valve (not shown), and an exhaust port (not shown) is opened / closed by an exhaust port (not shown). Each intake / exhaust valve is a well-known DOHC valve operating valve. It is driven by the system 4. The valve train 4 includes intake / exhaust cam shafts 5, 6 attached to the cylinder head 2 and intake / exhaust rocker shafts 7, 8.

Timing gears 9 and 10 are fixed to one ends of the intake and exhaust cam shafts 5 and 6, respectively.
0 is connected to the crankshaft side (not shown) via a timing belt 11 and is driven at a rotational speed of 1/2 of the engine speed. The intake / exhaust rocker shafts 7 and 8 are separately provided for each cylinder.

The intake and exhaust valves of each cylinder are constructed so as to be opened and closed by a known valve operating system, one example of which is as follows:
It is disclosed in the specification and drawings of Japanese Patent Application No. 4-232322 filed by the present applicant. The valve operating system is equipped with low / high switching means ML, MH as valve operation switching means which is an essential part of the variable valve drive mechanism. The low / high switching means ML, MH includes a low solenoid valve 26 for the 1 and 4 cylinders and a low solenoid valve 30 for the 2 and 3 cylinders, which connects the switching oil passage 23 to the hydraulic pump 25 in a discontinuous manner. Further, the low / high switching means ML and MH are provided with the switching oil passage 24.
Is connected to the hydraulic pump 25 in a discontinuous manner, and has a high solenoid valve 27 for the first and fourth cylinders and a high solenoid valve 31 for the second and third cylinders. The hydraulic pump 25 is communicatively connected to the oil tank as shown.

The low-high solenoid valves 26, 30, 27, 31 are each composed of a three-way valve, supply pressure oil to each hydraulic actuator (not shown) when turned on, and connect each hydraulic actuator to a drain when turned off. It is like this.
The low-high solenoid valves 26, 30, 27, 31 are connected to an engine control unit (ECU) 32, which will be described later, and are configured to perform a desired switching operation by a predetermined control signal.

Further, the low / high switching means ML, MH are
When both the low electromagnetic valves 26, 30 and the high electromagnetic valves 27, 31 are off, an intake / exhaust valve (not shown) is driven in the low speed mode. On the other hand, the low and high solenoid valves 26, 30, 27,
When both 31 are turned on, an intake / exhaust valve (not shown) is driven in the high speed mode. Furthermore, the low solenoid valve 26
If only ON, the first cylinder (# 1) as a deactivated cylinder
And the cylinder deactivation mode in which the intake and exhaust valves (not shown) of the fourth cylinder (# 4) are idly operated.

By the way, the cylinder head 2 is equipped with a fuel supply means FS. The fuel supply means FS includes four injectors 28 for injecting fuel into an intake port (not shown) of each cylinder, and a fuel pressure adjusting means 29. It has The fuel pressure adjusting means 29 is provided for each injector 28.
It is configured to supply the fuel from the fuel supply source 50 after adjusting the constant pressure, and these injectors 28 are
ECU 32 as fuel control means for performing injection drive control
It is connected to the.

As shown in FIG. 1, the ECU 32 is composed of a microcomputer as its main part, and is configured to perform injector drive control, ignition control, etc. according to an operation mode set according to operation information. There is. That is, in particular, as shown in FIG. 1, the ECU 32 includes a valve variable drive control means A1, a switching determination means A2, a fuel supply control means A3, an operation mode setting means A4, a fuel supply restriction means A6, and an empty space. In order to function as the fuel ratio detection means A7, the feedback control means A8, and the air-fuel ratio limit control stuck state detection means A9, it is configured as follows.

First, the operation mode setting means A4 selects either a low speed mode driven by a low speed cam or a high speed mode driven by a high speed cam as an all cylinder mode in which cylinders which can be stopped are not stopped, according to the operating state information of the engine, or , As the cylinder deactivation mode for deactivating the predetermined cylinder,
A cylinder deactivation mode in which four cylinders are idled is set as a target operation mode, and a switching signal for switching the current operation mode to the set target operation mode is output.

Then, the variable valve drive control means A1 controls the low / high switching means ML and MH as the valve operation switching means so that the variable valve drive control means A1 is brought into the operating state corresponding to the target operating mode set by the operating mode setting means A4. It is supposed to do. Further, when the target operation mode set by the operation mode setting means A4 is the all cylinder mode by the fuel supply control means A3, the fuel supply means FS related to the cylinders that can be deactivated is operated, and the target operation mode is the cylinder deactivation mode. At this time, the operation for deactivating the fuel supply means FS associated with a predetermined cylinder that can be deactivated is performed.

An air-fuel ratio detecting means A7 is provided to detect the operating air-fuel ratio of the engine on the basis of the detection signal of the O ₂ sensor 231, and the feedback control means A8 uses the detected air-fuel ratio to determine a predetermined air-fuel ratio. It is configured to perform fuel ratio control. Also, the feedback control means A
8 is provided with air-fuel ratio limit control stuck state detecting means A9 for detecting that the air-fuel ratio control is in a state of being stuck to the limit control. Means A8
Will be described later.

Further, the switching judging means A2 determines whether or not the switching from the valve non-operating state to the valve operating state based on the detection result of the air-fuel ratio limit control sticking state detecting means A9 is completed by the operation of the valve variable drive control means A1. To determine if
When it is determined that the switching is not completed, the switching incomplete signal is output. Further, when the switching determination means A2 outputs a switching incomplete signal, the fuel supply limiting means A6 outputs the required fuel supply means FS under the condition that the operating mode setting means A4 sets the all-cylinder mode.
The fuel supply control means A3 is configured to drive the fuel supply means FS in the cylinder deactivation mode.

The ECU 32 includes an engine rotation sensor 33 composed of a crank angle sensor and a water temperature sensor 34.
A negative pressure sensor 35, a throttle opening sensor 36,
An O ₂ sensor 231 is connected to these sensors, and by these sensors, the engine speed Ne, the water temperature WT, the intake negative pressure P
b, the throttle opening θs and the air-fuel ratio O2S are detected.

By the way, the above-mentioned air-fuel ratio detecting means A7, feedback control means A8, and air-fuel ratio limit control sticking state detecting means A9 are constructed as follows. That is, the operating air-fuel ratio O of the engine is detected by the O ₂ sensor 231.
S2 is detected, and this air-fuel ratio OS2
Is compared with the target air-fuel ratio VS, and when the air-fuel ratio OS2 exceeds the target air-fuel ratio VS on the rich side, the feedback control means A8 causes the fuel injection pulse width Tin.
A correction is made on the lean side of j.

That is, the fuel injection from the fuel supply means FS is performed by the injector 28 with the fuel injection pulse width Tinj.
The fuel injection pulse width Tinj can be corrected as desired by using the air-fuel ratio feedback control correction coefficient KF (KI) according to the following equation. Tinj = Tb × K × KF (KI) where Tb is the basic fuel injection time width Tb1 during all cylinder operation and the basic fuel injection time width Tb during cylinder deactivation operation.
1 and a predetermined value is stored in advance. Further, K is a correction value based on the air-fuel ratio command, water temperature, atmospheric temperature, atmospheric pressure, etc., and is set comprehensively from the control means corresponding to each.

KF (KI) is defined as a function including a proportional value (proportional gain) and an integral value (integral coefficient) KI. Therefore, as described above, the fuel injection pulse width Ti
nj is the air-fuel ratio feedback control correction coefficient KF (KI)
In the case of correcting to the lean side by, the integral value KI of the air-fuel ratio feedback control correction coefficient KF (KI) is reduced by a predetermined amount ΔI, and the fuel based on the reduced air-fuel ratio feedback control correction coefficient KF (KI) is The injection pulse width Tinj is calculated, and fuel injection in a leaner state is performed.

On the other hand, the operating air-fuel ratio OS2 is equal to the target air-fuel ratio VS.
When the operating air-fuel ratio OS2 does not exceed the target air-fuel ratio VS on the rich side, the feedback control means A8 corrects the fuel injection pulse width Tinj to the rich side. ing. That is, the integrated value KI is increased by a predetermined amount ΔI, and the increased air-fuel ratio feedback control correction coefficient KF
The fuel injection pulse width Tinj based on (KI) is calculated, and fuel injection in a richer state is performed.

Thus, the feedback control means A8
Is configured to increase or decrease the air-fuel ratio feedback control correction coefficient KF (KI) to converge the operating air-fuel ratio OS2 to the target air-fuel ratio VS. As a result, the normal operation shown in FIG. 10 is performed in the normal operation. That is, FIG. 10 shows the variation characteristic of the integrated value KI of the air-fuel ratio feedback control correction coefficient KF (KI) with respect to the time t on the horizontal axis, and in the normal state, repetition of increase and decrease around a predetermined value Become.

By the way, the air-fuel ratio limit control sticking state detecting means A9 is constructed so as to detect the state in which the integral value KI in the above-mentioned feedback control means A8 sticks to a predetermined lean side limit value IT. That is, a failure or the like occurs in any of the mechanisms in the valve variable drive control means A1 and the low / high switching means ML, MH, and when switching from the cylinder deactivated operation state to the all cylinder operation state, an incomplete switching state appears. Then, in the cylinder deactivation target cylinder, the fuel injection is performed in a state corresponding to the all-cylinder operation, although the valve is not operated.

Therefore, since the cylinder is in a rich state in which fuel is not consumed, the operating air-fuel ratio OS2 detected by the O ₂ sensor 231 has a value on the rich side, and in the feedback control means A8, the air-fuel ratio feedback control correction coefficient KF ( Correction for reducing the integrated value KI of KI) is performed. In the one-cylinder or two-cylinder failure state, this correction does not improve the enrichment tendency of the air-fuel ratio, so the lean correction is repeatedly executed until the lean-side limit correction value IT is reached. Since it is not allowed to set the integrated value KI of the air-fuel ratio feedback control correction coefficient KF (KI) to the lean side beyond the limit correction value IT, the integrated value K
The state in which I is set to the lean side limit correction value IT continues. Therefore, the air-fuel ratio limit control sticking state detection means A9 continues to set the integral value KI of such an air-fuel ratio feedback control correction coefficient KF (KI) as the limit correction value IT (hereinafter referred to as sticking).
It is configured to count the state (TIM4), and the switching determination means A2 determines the state in which the count value (TIM4) exceeds a predetermined number of times (or time: TNG) to determine whether one cylinder or two cylinders. Is configured to determine the fail state of the.

The determination based on the sticking of the air-fuel ratio feedback control correction coefficient KF (KI) is detected as shown in the region characteristic shown in FIG. Since the cylinder fail state is detected in the region of the lower right diagonal line, the one cylinder fail state is reliably detected. In FIG. 11, the horizontal axis represents the engine speed and the vertical axis represents the engine output.

The switching determination means A2 determines that the switching has not been completed when the following conditions are satisfied. (1) The feedback control based on the air-fuel ratio is being performed. (2) All cylinders are in operation. (3) A predetermined time T1 has elapsed from engine stall or starting, and the vehicle is in a steady operation state.

(4) The engine cooling water temperature WT is the predetermined value W
It is higher than T1 and is in a steady operation state. (5) The engine speed Ne is within a predetermined range and is in a steady operation state. (6) The throttle opening TPS detected by the throttle opening sensor 36 does not exceed the predetermined value TP2.

These determinations are made according to the flow chart described later. Then, this determination result is output from the switching determination means A2, and when it is determined that the switching has not been completed, the operation of the fuel supply means FS by the fuel supply control means A3 is restricted by the fuel supply restriction means A6.

That is, the fuel supply to the cylinder whose switching has not been completed is stopped, and the fuel is supplied to the other cylinder in the cylinder deactivated state. Next, various operations by the apparatus of this embodiment configured as described above will be described. First, the ECU 32 enters control in the main routine by keying on a main switch (not shown) (FIG. 5).

In this step, each function is checked and an initial function set such as initial value setting is performed (step p1), and subsequently various engine operation information is read (step p).
2) Then, a cylinder operation switching process is performed (step p3). In this cylinder operation switching process, the engine speed Ne and the shaft torque (calculated by a different routine from Pb and Ne) Te are used to determine whether or not each is in the cylinder deactivation operation range B1 as shown in FIG. When the cylinder deactivation condition is satisfied and the cylinder deactivation condition is satisfied, only the low solenoid valve 26 is turned on, and the other solenoid valves 30, 27,
All 31 are turned off, and the process returns to the main routine.

On the other hand, when the engine speed Ne at that time is smaller than the set value Ne1 '(see FIG. 3), the low speed mode is set, and when it is not small, the high speed mode is set, and the low speed mode is set to low high. Solenoid valves 26, 30, 2
Achieve low speed mode by switching off all 7, 31
In the high speed mode, all of the low and high solenoid valves 26, 30, 27, 31 are turned on to achieve the high speed mode, and the process returns.

After this, when steps p3 to p4 of the main routine are performed, the fuel supply process described below is performed in step p5.
Then, the engine control process is performed, and the process returns to step p2. By the way, in the fuel supply process of step p4, correction values such as the air-fuel ratio of the injector driving process to be interrupted, the water temperature, the atmospheric temperature, and the atmospheric pressure are calculated in advance. Then, the injector drive processing as shown in FIG. 6 is executed in synchronization with the interruption of the crank pulse during the intake stroke of each cylinder.

That is, in step g1 shown in FIG.
The flag FCFIG indicating whether or not the current fuel cut area is present is referred to. If FCFIG = “1”, it is in the fuel cut area, and therefore the routine returns. On the other hand, FCF
If IG = “1” is not satisfied, step g2 is executed through the “NO” route, and at that time also, the basic injection pulse width Tb1 during all-cylinder operation according to the intake air information (air-fuel ratio A / N, boost pressure Pb). And basic injection pulse width T during cylinder deactivation operation
Calculate b2.

Next, at step g3, it is judged whether or not the cylinder is in the cylinder deactivation mode, and "YES" is set in the cylinder deactivation mode.
Step g7 is executed through the route. Step g7
Then, the target injection time width Tinj is calculated by correcting the basic injection pulse width Tb2 during cylinder deactivation operation with the correction value K such as the air-fuel ratio command, the water temperature, the atmospheric temperature, and the atmospheric pressure. Further, the target injection time width Tinj is also corrected by the air-fuel ratio feedback control correction coefficient KF (KI).

Then, the driver of the constantly operating cylinder is operated by the pulse of the target injection time width Tinj, and the injector 2
Fuel injection into the corresponding cylinders (# 2, # 3) is performed by the No. 8 engine. At this time, the first cylinder (# 1) and the fourth cylinder (# 4)
Fuel injection to the engine is stopped. On the other hand, if it is determined in step g3 that the cylinder is not in the cylinder deactivation mode, the processing from step g4 onward is performed through the "NO" route.

First, when there is no incomplete switching (failed cylinder) to the all cylinder mode in the cylinders subject to cylinder deactivation, the "NO" route is taken in step g4, and step g
5, operation in the all cylinder mode is performed in step g6. That is, in step g5, the target injection time width Tinj is calculated by correcting the basic injection pulse width Tb1 during all-cylinder operation with the correction value K corresponding to the air-fuel ratio command, the water temperature, the atmospheric temperature, the atmospheric pressure, and the like.

The target injection time width Tinj is also corrected by the air-fuel ratio feedback control correction coefficient KF (KI). Then, in step g6, the drivers of all the cylinders are operated by the pulse of the target injection time width Tinj, and the fuel is injected into all the cylinders by the injector 28.

By the way, when there is a fail cylinder whose switching to the all-cylinder operating state has not been completed among the two cylinders subject to cylinder deactivation, the following operation is performed. That is, in the failure flag setting routine shown in FIGS.
When either or both of the first cylinder and the fourth cylinder are fail cylinders, the failure flag FF1 becomes "1", so the "YES" route is taken in step g4, and steps g7 and g8 are executed. To be done. This is the same as the operating state in the cylinder deactivation mode, and when one or both of the two cylinders subject to cylinder deactivation are in failure, the cylinder deactivation operation is performed.

By the way, the feedback control routine based on the air-fuel ratio is constructed as shown in FIG. 7, and the operation along each step is performed as follows. First, in step SA, it is judged whether or not the feedback control based on the detection signal from the O ₂ sensor 231 is being performed, and if the feedback control is not being performed, the return operation is performed through the “NO” route.

On the other hand, when the feedback control is being performed, steps SA2 and thereafter are executed. At step SA2, the engine operating air-fuel ratio OS2 detected by the O ₂ sensor 231 and the preset target air-fuel ratio VS
When the operating air-fuel ratio OS2 exceeds the target air-fuel ratio VS on the rich side, the feedback control means A8 corrects the fuel injection pulse width Tinj to the lean side in step SA3 and subsequent steps.

That is, in step SA3, when the fuel injection pulse width Tinj is corrected to the lean side,
As shown in the following equation, the air-fuel ratio feedback control correction coefficient KF
The integrated value KI of (KI) is reduced by a predetermined amount ΔI. KI = KI-ΔI Then, the fuel injection pulse width Tinj is calculated by the air-fuel ratio feedback control correction coefficient KF (KI) thus reduced by the integrated value KI, and fuel injection in a leaner state is performed. become.

On the other hand, the operating air-fuel ratio OS2 is equal to the target air-fuel ratio VS.
If the operating air-fuel ratio OS2 does not exceed the target air-fuel ratio VS on the rich side, step SA4 is executed through the "NO" route, and the feedback control means A8 causes the fuel injection pulse width Tinj to be increased. Is corrected to the rich side. That is, the integral value KI of the air-fuel ratio feedback control correction coefficient KF (KI) is increased by a predetermined amount ΔI as in the following equation.

KI = KI + ΔI Then, the fuel injection pulse width Tinj is calculated by the air-fuel ratio feedback control correction coefficient KF (KI) thus increasing the integrated value KI, and fuel injection in a richer state is performed. Will be done. Then, the integrated value KI calculated in step SA3 as described above.
Is compared with a predetermined lean side limit correction value IT in step SA7, and the integrated value KI is lean side limit correction value I.
When T does not exceed the lean side, the integrated value KI is returned without change.

On the other hand, the integral value KI is the lean side limit correction value I.
If T exceeds the lean side, correction exceeding the limit is not preferable, so the integrated value KI is set to the lean side limit correction value I.
After changing to T (step SA8), the process is returned. Further, the integrated value KI calculated in step SA4 as described above is compared with the predetermined rich side limit correction value IS in step SA5, and the integrated value KI does not exceed the rich side limit correction value IS on the rich side. In case of integrated value K
It returns without changing I.

On the other hand, the integrated value KI is the rich side limit correction value I.
If S exceeds the rich side, correction exceeding the limit is not preferable, so the integrated value KI is set to the rich side limit correction value I.
After changing to S (step SA6), the process is returned. By performing the fuel injection control while correcting the fuel injection pulse width Tinj based on the integral value KI calculated in this way, the feedback control based on the air-fuel ratio is performed.

That is, the feedback control means A8
Controls to increase or decrease the air-fuel ratio feedback control correction coefficient KF (KI) to converge the operating air-fuel ratio OS2 to the target air-fuel ratio VS. As a result, the normal operation shown in FIG. 10 is performed in the normal operation. That is, FIG. 10 shows the variation characteristic of the integrated value KI of the air-fuel ratio feedback control correction coefficient KF (KI) with respect to the time t on the horizontal axis, and in the normal state, repetition of increase and decrease around a predetermined value Become.

By the way, when a failure or the like occurs in any of the various mechanisms of the valve variable drive control means A1 and the low / high switching means ML, MH, when switching from the cylinder deactivation operation state to the all cylinder operation state, the switching is not completed. When a state appears, in the cylinder deactivation target, fuel injection is performed in a state corresponding to the all-cylinder operation, although the valve is not operated.

In this case, since the cylinder is in a rich state in which fuel is not consumed, the operating air-fuel ratio OS2 detected by the O ₂ sensor 231 becomes a value on the rich side, and the feedback control means A8 uses the air-fuel ratio feedback control correction coefficient KF. Correction is performed to reduce the integrated value KI of (KI). Then, with this correction, the failure state of one cylinder or two cylinders cannot be eliminated, and the tendency of enrichment of the air-fuel ratio cannot be improved.

Therefore, the lean correction is repeatedly executed until the integral value KI reaches the lean limit correction value IT. Then, the integrated value KI exceeds the limit correction value IT, but the integrated value KI is not allowed to exceed the limit correction value IT and is set to the lean side. Therefore, the integrated value KI is lean. Side limit correction value IT
The state set to will be continued. Such a state is a state in which the integral value KI is stuck to the limit correction value IT, and this state is detected by the air-fuel ratio limit control sticking state detection means A9.

The detected sticking state is referred to in the failure flag setting routine shown in FIG. 8 and the failure flag setting routine shown in FIG. The failure flag setting routine shown in FIG. 8 will be described. First, in steps SB1 to SB6, it is determined whether or not the steady operation state has reached a level where the determination of the failure flag can be made under the following conditions. Be done.

(1) The feedback control based on the air-fuel ratio is being performed (step SB1). (2) All cylinders are in operation (step SB2). (3) The engine cooling water temperature WT is higher than a predetermined value WT1 and is in a steady operation state (step SB
3). (4) As a condition of the steady operation state, the engine speed Ne is within a predetermined range (low speed side threshold NeL and high speed side threshold N
eH)) (step SB4).

(5) A predetermined time T1 has elapsed from the engine stall or starting, and the vehicle is in a steady operation state (step SB
5). (6) The throttle opening TPS detected by the throttle opening sensor 36 is not larger than the predetermined value TP2 (step SB6). If these conditions are not satisfied, the timer TIM4 is set to "0" in step SB12 through the "NO" route.
And the flag F1 is reset to "0", the return operation is performed.

On the other hand, if the above conditions are satisfied, the operation has reached a steady operating state to the extent that the determination of the failure flag setting can be made, so the processing from step SB7 is executed. First, in step SB7 which constitutes the air-fuel ratio limit control sticking state detecting means A9, it is judged whether or not the integral value KI is larger than the lean side limit correction value IT, and if it is larger, the timer TIM4 is set to "0". After being reset (step SB8), the state becomes ready for detecting the stuck state of the integrated value KI.

On the other hand, when the integral value KI is not larger than the lean side limit correction value IT (when KI = IT),
The timer TIM4 is incremented by a predetermined amount and the flag F1 is set to "1" (step SB
9). This state is the limit correction value I of the so-called integral value KI.
It is in the state of sticking to T, and the time in this sticking state is counted.

Then, in step SB10 which constitutes the switching judgment means A2, it is judged whether or not the timer TIM4 has exceeded a predetermined number (or time: TNG). That is, when the timer TIM4 exceeds the predetermined number (or time: TNG), it is indicated that the sticking state of the integral value KI to the limit correction value IT should be the one-cylinder or two-cylinder fail determination. Therefore, the failure flag FF1 is set to "1" in step SB11 through the "YES" route.

On the other hand, when the timer TIM4 does not exceed the predetermined number (or time: TNG), the integral value K
One cylinder or two sticking state of I to the limit correction value IT
This indicates that the state in which the failure determination of the cylinder should be made has not been reached, and through the “NO” route, step SB1
The return operation is performed without setting the failure flag FF1 in 1.

In this way, the air-fuel ratio detecting means A7,
The failure flag is set by the air-fuel ratio detecting means A7 and the air-fuel ratio limit control sticking state detecting means A9. Next, the failure flag setting routine shown in FIG. 9 will be described.
The parts up to 12 are configured in the same manner as in steps SB1 to SB11 in FIG.
The failure flag is set by similar processing.

Then, in this routine, in addition to the processing of FIG. 8, the processing of steps SC13 to SC16 is performed. First, step SC13 is step SC2.
If it is determined that the operation is not in the all-cylinder operation, the process is executed in the so-called cylinder deactivation operation. Next, step SC1 of constituting the air-fuel ratio limit control sticking state detecting means A9.
3, the integral value KI is the limit correction value IT on the lean side.
If it is larger, the timer TIM9 is reset to "0" (step SC
14), the state is ready for detecting the stuck state of the integrated value KI.

On the other hand, when the integral value KI is not larger than the lean side limit correction value IT (when KI = IT),
The timer TIM9 is counted up by a predetermined amount. This state is a state in which the so-called integral value KI is stuck to the limit correction value IT, and the time in this stuck state is counted. Then, the switching determination means A
2 in step SC15, the timer TI
It is determined whether M9 exceeds a predetermined number (or time: TFA).

That is, when the timer TIM9 has exceeded the predetermined number of times (or time: TFA), it is necessary to make a fail determination of whether the sticking state of the integral value KI to the limit correction value IT is one cylinder or two cylinders. This means that the check lamp is turned on in step SC16 through the “YES” route. This is a case where a valve mechanism, a fuel injection system, or the like has failed in a normally operating cylinder that is not subject to cylinder deactivation in the cylinder deactivation operation state, and notifies the driver to that effect.

When the timer TIM4 does not exceed the predetermined number (or time: TNG), the limit correction value I of the air-fuel ratio feedback control correction coefficient KF (KI)
It shows that the state of sticking to T has not reached the state where the failure determination of one cylinder or two cylinders should be performed,
Through the “NO” route, the check lamp is not turned on in step SC16, and the return operation is performed via step SC17.

In this way, the air-fuel ratio detecting means A7,
A failure flag is set by the air-fuel ratio detecting means A7 and the air-fuel ratio limit control sticking state detecting means A9, and the valve mechanism and the fuel injection system for the normally operating cylinders not subject to the cylinder deactivation in the cylinder deactivation operation state are set. About failure occurrence,
The check lamp is turned on. The determination based on the sticking of the integrated value KI is detected as shown in the region characteristics shown in FIG. 11, the one-cylinder fail state is detected in the upward-sloping oblique line region, and the two-cylinder fail state is in the downward-sloping oblique line region. Therefore, it can be reliably detected from the single-cylinder fail state. Here, in FIG. 11, the horizontal axis represents the engine speed and the vertical axis represents the engine output.

Then, the above judgment result is output from the switching judgment means A2, and when it is judged that the switching is not completed, the operation of the fuel supply means FS by the fuel supply control means A3 is
It is limited by the fuel supply limiting means A6. That is, the fuel supply to the cylinder whose switching has not been completed is stopped, and the fuel is supplied to the other cylinder in the cylinder deactivated state.

As described above, both the one-cylinder failure and the two-cylinder failure can be reliably detected,
Even during a fail, stable and reliable control will be performed. Further, such an effective control can be obtained only by changing the software without changing the hardware configuration, and the reliable control can be performed without a cost problem.

[0079]

As described above in detail, according to the fuel control apparatus for an engine with a cylinder deactivation mechanism of the present invention, the opening / closing operation of at least one of the intake valve and the exhaust valve is made to be in the operating state by the valve operation switching means. In an engine with a cylinder deactivation mechanism having a deactivating cylinder that can be selectively switched between an operating state and a deactivating cylinder mode in which the deactivating cylinder is not deactivated and a predetermined cylinder is deactivated. An operation mode setting means for setting a target operation mode according to the operating state information, and a valve variable drive control means for controlling the valve operation switching means so that the operation mode is set to an operation state corresponding to the target mode set by the operation mode setting means. And a fuel supply corresponding to the target operating mode set by the operating mode setting means and related to the restable cylinders in the all cylinder mode. An air-fuel ratio detecting means for detecting the air-fuel ratio of the engine, and a fuel supply control means for deactivating the fuel supply means associated with a predetermined deactivated cylinder in the cylinder deactivation mode. Air-fuel ratio feedback control means for performing feedback control for fuel supply to the engine using the air-fuel ratio detected by the fuel ratio detection means, and comparing the feedback control amount by the air-fuel ratio feedback control means with a predetermined threshold value. Whether the air-fuel ratio limit control sticking state detecting means for detecting the sticking state to the rich side limit control is provided and whether the switching from the valve non-operating state to the valve operating state by the operation of the valve variable drive control means is completed. If it is determined that the switching is not completed, it is determined that the switching is not completed based on the detection result of the air-fuel ratio limit control sticking state detection means. When the switching determination means outputs the completion signal and the switching determination means outputs the switching incompletion signal under the condition that the operation mode setting means sets the all cylinder mode, the required fuel supply means is deactivated. The simple structure of being equipped with the fuel supply limiting means has the following effects and advantages.

(1) Both the one-cylinder failure and the two-cylinder failure are reliably detected, and stable and reliable control is performed even during the failure. (2) The effect of the preceding paragraph can be obtained only by changing the software without changing the hardware configuration, and the reliable control can be performed without problems in cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control system of a fuel control device for an engine with a cylinder deactivation mechanism as an embodiment of the present invention.

FIG. 2 is an overall configuration diagram showing an engine system to which a fuel control device for an engine with a cylinder deactivation mechanism according to an embodiment of the present invention is applied.

FIG. 3 is a characteristic diagram showing control characteristics of a fuel control device for an engine with a cylinder deactivation mechanism according to an embodiment of the present invention.

4A and 4B are characteristic diagrams showing control characteristics of a fuel control system for an engine as an embodiment of the present invention.

FIG. 5 is a flowchart showing a control procedure of a fuel control device for an engine with a cylinder deactivation mechanism as an embodiment of the present invention.

FIG. 6 is a flowchart showing a control procedure of a fuel control device for an engine with a cylinder deactivation mechanism as one embodiment of the present invention.

FIG. 7 is a flowchart showing a control procedure of a fuel control device for an engine with a cylinder deactivation mechanism as an embodiment of the present invention.

FIG. 8 is a flow chart diagram showing a control procedure of a fuel control device for an engine with a cylinder deactivation mechanism as one embodiment of the present invention.

FIG. 9 is a flowchart showing a control procedure of a fuel control device for an engine with a cylinder deactivation mechanism as an embodiment of the present invention.

FIG. 10 is a diagram showing control characteristics of a fuel control device for an engine with a cylinder deactivation mechanism as one embodiment of the present invention.

FIG. 11 is a diagram showing control characteristics of a fuel control device for an engine with a cylinder deactivation mechanism as one embodiment of the present invention.

FIG. 12 is a diagram showing a conventional fail characteristic due to intake pipe pressure.

FIG. 13 is a diagram showing a conventional fail determination characteristic based on intake pipe pressure.

[Explanation of symbols]

1 engine 2 cylinder head 4 valve system 5 intake / exhaust cam shaft 6 intake / exhaust cam shaft 7 intake / exhaust rocker shaft 8 intake / exhaust rocker shaft 9 timing gear 10 timing gear 11 timing belt 23 switching oil passage 24 switching oil passage 25 hydraulic pump 26 low and high electromagnetic valve 27 Low / High Solenoid Valve 28 Injector 29 Fuel Pressure Adjusting Means 30 Low / High Solenoid Valve 31 High Solenoid Valve for 2 and 3 Cylinders 32 Engine Control Unit (ECU) 33 Engine Rotation Sensor (Crank Angle Sensor) 34 Water Temperature Sensor 35 Negative Pressure Sensor 36 throttle opening sensor 37 surge tank 38 air cleaner 40 throttle valve 41 rotation shaft 42 valve drive actuator 50 fuel supply source 231 O ₂ sensor A1 valve variable actuation control means A2 switching determination unit A3 fuel supply means A4 operation mode setting means A Rotational fluctuation detection means A6 Fuel supply control means A7 Air-fuel ratio detection means A8 Feedback control means A9 Air-fuel ratio limit control Sticking state detection means FS Fuel supply means KL low switching means KH high switching means # 2, # 3 Always operating cylinders # 1, # 4 cylinder deactivated

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location F02D 17/02 R 41/14 310 A (72) Inventor Toshiyuki Miyata 5-3-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Kazutoshi Noma 5-3-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Tetsuo Maeda 13-13 Sadamoto-cho, Himeji-shi, Hyogo Mitsubishi Electric Control Software Co., Ltd. Himeji Office

Claims (1)

[Claims] 1. An engine with a cylinder deactivation mechanism, comprising a cylinder capable of pausing, capable of selectively switching the opening / closing operation of at least one of an intake valve and an exhaust valve between an operating state and a non-operating state by means of a valve operation switching means, By the operation mode setting means for setting either the all cylinder mode that does not stop the restable cylinder or the rest cylinder mode that suspends the predetermined cylinder as the target operation mode according to the operating state information of the engine, and the operation mode setting means. It corresponds to the valve variable drive control means for controlling the valve operation switching means so as to be in the operating state corresponding to the set target mode, and the target operating mode set by the operating mode setting means. In addition to activating the fuel supply means associated with the deactivated cylinders, the fuel related to the prescribed deactivated cylinders is activated in the cylinder deactivation mode. Fuel supply control means for deactivating the fuel supply means, air-fuel ratio detection means for detecting the air-fuel ratio of the engine, and fuel supply to the engine using the air-fuel ratio detected by the air-fuel ratio detection means. Air-fuel ratio feedback control means for performing feedback control for the air-fuel ratio limit control, and comparing the feedback control amount by the air-fuel ratio feedback control means with a predetermined threshold value to detect the sticking state to the rich side limit control Means for determining whether or not the switching from the valve non-operating state to the valve operating state by the operation of the valve variable drive control means is completed based on the detection result of the air-fuel ratio limit control sticking state detecting means. If it is determined that the switching is not completed, the switching determination means that outputs a switching incomplete signal and the operation mode setting means are provided for all cylinder models. Wherein the situation that sets a de in constructed and a non-working and forming fuel supply limiting means required of the fuel supply means and for outputting the incomplete signal switching is the switching determination means,
Fuel control system for engines with cylinder deactivation mechanism.