JPH06280636A - Control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To appropriately control the purge volume so as to adjust the output power of an internal combustion engine to a suitable value and to reduce evaporating emission by setting the opening degree of a second throttle valve to a value with which the volume of fuel vapor is not excessively fed. CONSTITUTION:Fuel vapor trapping means M3 traps fuel vapor generated from a fuel tank M2. Further, fuel vapor supply means M4 introduces the fuel vapor into an intake-air passage IN between first and second throttle valves TV1, TV2 with the use of vacuum in the intake-air passage IN. Meanwhile, excessive supply preventing condition storing means M5 stores therein conditions with which the fuel vapor is prevented from being excessively fed. Lower opening limit value calculating means M7 obtains a lower limit value for the first throttle valve TV1. Further, control limiting means M8 limits the control of second throttle valve control means Ml so as to prevent the opening degree of the second throttle valve TV2 from becoming lower than thus obtain lower limit value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine control device, and more particularly to an internal combustion engine for controlling the output of an internal combustion engine by opening and closing a second throttle valve provided in the intake passage in addition to the first throttle valve. Regarding the control device.

[0002]

2. Description of the Related Art Conventionally, a first throttle valve (which is interlocked with an accelerator pedal) is provided in an intake passage of an internal combustion engine for the purpose of suppressing acceleration slip during vehicle operation.
In addition, there is known an internal combustion engine control device in which a second throttle valve (not interlocked with the accelerator pedal) is provided and the output torque of the internal combustion engine is suppressed by controlling the opening / closing of the second throttle valve.

On the other hand, there is known a technique provided with a canister which temporarily collects the fuel purge evaporated from the fuel tank by using activated carbon so as not to release it into the atmosphere. Since the capacity of this canister is constant, the collected fuel purge must be sucked into the intake system of the internal combustion engine at an appropriate time and burned together with the fuel mixture for processing. This process is so-called canister purge, and the device that executes this canister purge uses the negative pressure generated in the intake passage to suck out the fuel purge stored in the canister.

Against this background, there is a demand for the development of a vehicle with high added value that can perform output control by the second throttle valve and canister purge. However, in such a vehicle, the opening degree of the second throttle valve is set to the first opening degree by controlling the opening / closing of the second throttle valve.
When the throttle valve is controlled to be closer to the opening side than the opening degree of the throttle valve, even though the first throttle valve is in the fully open state, the negative pressure is not generated and the canister purge is not executed, but the second throttle valve is operated. A negative pressure may be generated between the valve and the first throttle valve, and the negative pressure may cause the canister purge. Therefore, when the fuel purge is sucked from the canister when it is not necessary and the fuel mixture becomes overrich, the configuration shown in Japanese Patent Laid-Open No. 271038/1990 is proposed as a solution to this problem. This configuration prohibits execution of canister purge when the opening of the second throttle valve is controlled to be closer to the closing side than the opening of the first throttle valve.

[0005]

In such an internal combustion engine control system, the evaporative emission emitted from the fuel system into the atmosphere is naturally increased as much as the canister purge is prohibited. When the output control of the internal combustion engine is performed for the purpose of accelerating slip of the vehicle as described in Japanese Patent Laid-Open No. 271038/1990, the operation frequency is relatively low, and therefore even if the execution of the canister purge is prohibited, the emission of the emission is reduced. The increase will not be so affected. On the other hand, when the second throttle valve is operated almost all the time for the purpose of controlling the active throttle opening (a so-called electronic throttle valve), the opening of the second throttle valve is Since the opening of the first throttle valve is always controlled to be closed, the canister purge is hardly executed.
Therefore, the increase of evaporative emission became a big problem.

The internal combustion engine control device of the present invention has been made in view of these problems, and the purge amount can be appropriately controlled even when the opportunity to control the opening / closing of the second throttle valve increases. Therefore, the purpose is to appropriately adjust the output of the internal combustion engine and to reduce the evaporative emission.

[0007]

In order to achieve such an object, the following constitution is adopted as a means for solving the above problems. That is, the first internal combustion engine control device of the present invention, as illustrated in the block diagram of FIG.
In the G intake passage IN, a first throttle valve TV1 interlocked with the accelerator pedal AC and a second throttle valve TV located upstream of the first throttle valve TV1.
2 and the second throttle valve control means M1 adjusts the opening of the second throttle valve TV2 to control the output of the internal combustion engine EG independently of the operation of the accelerator pedal AC. The fuel vapor collecting means M3 for temporarily collecting the fuel vapor generated in the fuel tank M2, and the collected fuel vapor by the negative pressure in the intake passage IN by the first throttle valve The fuel vapor supply means M4 introduced into the intake passage IN between the TV1 and the second throttle valve TV2, and the condition for avoiding excessive supply of fuel vapor by the fuel vapor supply means M4 are defined as follows. Excessive supply avoidance condition storage means M5 stored in advance as a lower limit value of the opening of the second throttle valve TV2 that is determined according to the opening, and the first throttle. The first throttle valve opening detection means M6 for detecting the opening of the valve TV1 and the first throttle valve detected by the first throttle valve opening detection means M6 from the stored contents of the excessive supply avoidance condition storage means M5. The second throttle valve T based on the opening degree of the TV 1.
Opening lower limit value calculating means M7 for obtaining the lower limit value of the opening of V2
And the second throttle valve control means M so that the opening degree of the second throttle valve TV2 does not become smaller than the lower limit value obtained by the opening lower limit value calculating means M7.
The gist is that it is provided with a control limiting means M8 for limiting the control by 1.

Further, the second internal combustion engine control apparatus of the present invention, as illustrated in the block diagram of FIG. 2 (the same elements as those in the first configuration are designated by the same reference numerals), has the internal combustion engine EG.
In the intake passage IN of the first throttle valve TV1 interlocked with the accelerator pedal AC, and the second throttle valve TV2 located upstream of the first throttle valve TV1.
And an internal combustion engine control device that controls the output of the internal combustion engine EG independently of the operation of the accelerator pedal AC by adjusting the opening of the second throttle valve TV2 by the second throttle valve control means M1. Therefore, the fuel vapor collecting means M3 for temporarily collecting the fuel vapor generated in the fuel tank M2 and the collected fuel vapor by the negative pressure in the intake passage IN by the first throttle valve TV1. And the second throttle valve TV2, the fuel vapor supply means M4 introduced into the intake passage IN, and the condition for avoiding excessive supply of fuel vapor by the fuel vapor supply means M4 are the opening of the first throttle valve TV1. The excessive supply avoidance condition storage means M5 stored in advance as a lower limit value of the opening degree of the second throttle valve TV2 which is determined according to the first throttle valve TV2. The first throttle valve opening detection means M6 for detecting the opening of the TV1 and the first throttle valve detected by the first throttle valve opening detection means M6 from the stored contents of the oversupply avoidance condition storage means M5. The second throttle valve TV based on the opening of the TV 1.
Opening lower limit value calculating means M7 for obtaining the lower limit value of the opening of 2;
When the opening degree of the second throttle valve TV2 adjusted by the second throttle valve control means M1 is smaller than the lower limit value obtained by the opening lower limit value calculating means M7, the fuel vapor supply means M4 operates the fuel vapor. The gist is that the fuel vapor supply prohibiting means M18 for prohibiting the supply is provided.

[0009]

In the first internal combustion engine control apparatus of the present invention configured as described above, the fuel vapor generated in the fuel tank M2 is collected by the fuel vapor collecting means M3, and the fuel vapor is collected by the fuel vapor. The supply means M4 uses the negative pressure in the intake passage IN to guide it into the intake passage IN between the first throttle valve TV1 and the second throttle valve TV2.
On the other hand, in the excessive supply avoidance condition storage means M5, the condition for avoiding the excessive supply of fuel vapor by the fuel vapor supply means M4 is determined according to the opening degree of the first throttle valve TV1. Is stored in advance as the lower limit value of the first throttle valve opening degree detection means M by the opening lower limit value calculation means M7.
The lower limit value is obtained based on the opening degree of the first throttle valve TV1 detected in 6. Then, the control by the second throttle valve control means M1 is restricted by the control restriction means M8 so that the opening degree of the second throttle valve TV2 does not become smaller than the obtained lower limit value.

Therefore, by controlling the opening / closing of the second throttle valve TV2, the opening of the second throttle valve TV2 is controlled to be closer to the closing side than the opening of the first throttle valve TV1, and a negative pressure should not be generated. When a negative pressure is generated in the operating range of 10 and the fuel vapor is supplied from the fuel vapor supply means M4, the second throttle valve control means M1 controls the opening degree of the second throttle valve TV2 and the control restriction means M8. The fuel vapor supply is prevented from becoming excessive by restricting the fuel vapor. Therefore, it works to properly adjust the purge amount of the fuel vapor. Furthermore, as compared with the conventional one in which execution of the canister purge is prohibited when the opening of the second throttle valve is controlled to be closer to the closing side than the opening of the first throttle valve, the prohibition condition is satisfied. Even if the supply of fuel paper does not become excessive, it works to execute the supply.

In the second internal combustion engine control device of the present invention, the lower limit value of the opening of the second throttle valve TV2 is obtained by the opening lower limit value calculating means M7 in the same manner as the first internal combustion engine control device. , Second throttle valve control means M1
When the opening degree of the second throttle valve TV2 adjusted by is smaller than the lower limit value thereof, the fuel vapor supply prohibiting means M1 controls the supply of fuel vapor by the fuel vapor supplying means M4.
Prohibit by 8.

Therefore, the opening / closing control of the second throttle valve TV2 controls the opening degree of the second throttle valve TV2 to be closer to the closing side than the opening degree of the first throttle valve TV1. When a negative pressure is generated in the operating range and the fuel vapor is supplied from the fuel vapor supply means M4, the time when the supply of the fuel vapor becomes excessive is determined from the opening degree of the second throttle valve TV2, When it becomes excessive, the supply of fuel vapor is prohibited. Therefore, it works to properly adjust the purge amount of the fuel vapor, and even when the opening of the second throttle valve TV2 is controlled to be closer to the closing side than the opening of the first throttle valve TV1. Will work to carry out that supply unless it is in excess.

[0013]

Preferred embodiments of the present invention will be described below in order to further clarify the structure and operation of the present invention described above. FIG. 3 is a schematic configuration diagram showing an automobile engine as an internal combustion engine control device and its peripheral devices according to a first embodiment of the present invention.

As shown in FIG. 1, the intake passage 2 of the engine 1 is provided with a main throttle valve 4 connected to an accelerator pedal 3 by a mechanical link, and a sub-throttle valve 5 provided upstream thereof. The sub-throttle valve 5 is driven by the throttle actuator 6. Further, downstream of the main throttle valve 4, a surge tank 7 for suppressing pulsation of intake air and a fuel injection valve 8 for injecting fuel into the engine 1 are provided.

The amount of intake air taken in through the intake passage 2 is controlled by the opening / closing control of the main throttle valve 4 by the driver's operation of the accelerator pedal 3 and the opening / closing control of the sub throttle valve 5 by the throttle actuator 6. The fuel is adjusted, mixed with the fuel injected from the fuel injection valve 8, and sucked into the combustion chamber 11 of the engine 1.
This fuel-air mixture is spark-ignited by the spark plug 12 in the combustion chamber 11 to drive the engine 1. Combustion chamber 1
The gas (exhaust gas) that has burned in 1 is guided to the catalytic converter 16 via the exhaust passage 15, is purified, and is then discharged to the atmosphere side.

Further, a purge pipe 21 is connected between the main throttle valve 4 and the sub throttle valve 5 in the intake passage 2 of the engine 1. At the other end of the purge pipe 21, a canister 2 having activated carbon inside is provided.
2 are connected to each other, and the steam pipe 2 is connected to the canister 22.
A fuel tank 24 is connected via 3. The fuel purge evaporated in the fuel tank 24 is once adsorbed by the activated carbon in the canister 22 via the vapor pipe 23 and once retained, and then, via the purge pipe 21, both throttle valves 4, 5 are released.
Is sucked into the intake passage 2 due to the negative pressure. Thus, the fuel purge evaporated in the fuel tank 24 is sucked into the combustion chamber 11 and burned together with the fuel mixture.

In the engine 1 having such a configuration, as a sensor for detecting the operating state thereof, a rotation speed sensor 50, which is provided in the distributor 29 and outputs a pulse signal of 24 times per revolution, and the opening degree of the main throttle valve 4. , A second throttle position sensor 52 for detecting the opening of the sub-throttle valve 5, an intake air temperature sensor 53 arranged in the intake passage 2 for detecting the temperature of intake air (intake air), A vacuum sensor 54 provided in communication with the surge tank 7 for detecting the pressure in the intake passage, a water temperature sensor 55 provided in the cylinder block for detecting the cooling water temperature, and the exhaust passage 1
5, an oxygen concentration sensor 56 and the like arranged upstream of the catalytic converter 16 for detecting the oxygen concentration in the exhaust gas are provided. Detection signals from these sensors are input to an electronic control unit (hereinafter referred to as ECU) 70.

As shown in FIG. 4, the ECU 70 is constructed as a logical operation circuit centered on a microcomputer, and more specifically, a C for executing various arithmetic processes for controlling the engine 1 in accordance with a preset control program.
The PU 70a, the ROM 70b in which control programs and control data necessary for executing various arithmetic processes by the CPU 70a are stored in advance, and various data required for executing various arithmetic processes by the CPU 70a are temporarily read and written. RAM 70c, a backup RAM 70d capable of holding data even when the power is off, an A / D converter 70e and an input processing circuit 70f for inputting detection signals from the above-mentioned sensors, and a throttle actuator according to a calculation result in the CPU 70a 6 and fuel injection valve 8
An output processing circuit 70g and the like for outputting a drive signal is provided.

With the ECU 70 thus configured,
The throttle actuator 6 and the fuel injection valve 8 are drive-controlled according to the operating state of the engine 1, and sub throttle valve opening control, fuel injection control, air-fuel ratio control, etc. are performed.

Next, the fuel injection control processing routine executed by the CPU 70a of the ECU 70 will be described with reference to FIG. It should be noted that this control processing routine is executed every predetermined crank angle, for example, every 360 ° CA.

When the processing is started, the CPU 70a first stores the intake pressure Pm detected by the vacuum sensor 54 and A / D converted by the A / D converter 70e in the RAM 70.
The process of reading from c is executed (step S100).
Next, the input processing circuit 7 detected by the rotation speed sensor 50.
The rotation speed Ne input via 0f is transferred to the RAM 70c.
The process of reading from is executed (step S110).

Subsequently, steps S100 and S110.
The basic fuel injection amount TP is calculated according to a predetermined function f using the intake pressure Pm and the rotation speed Ne read in (step S120). Then, the actual fuel injection amount TAU is calculated by multiplying and adding various correction coefficients to the basic fuel injection amount TP so as to comply with the following equation (1) (step S130). TAU ← TP ・ FAF ・ FWL ・ α + β (1)

Where FAF is an air-fuel ratio correction coefficient,
It is calculated by a processing routine that performs feedback control so that the output signal of the oxygen concentration sensor 56 becomes a reference level corresponding to the stoichiometric air-fuel ratio. FWL is a warm-up increase correction coefficient and takes a value of 1.0 or more while the cooling water temperature THW is 60 ° C. or less. α and β are other correction factors, for example, correction factors relating to intake air temperature correction, transient correction, and the like.

When the actual fuel injection amount TAU is calculated in step S130, subsequently, the fuel injection time corresponding to the actual fuel injection amount TAU is set in a counter (not shown) for determining the valve opening time of the fuel injection valve 8 ( Step S14
0). As a result, the fuel injection valve 8 is driven to open for the valve opening time set in the counter. After that, the process returns to "return" and the process is terminated. In this way, fuel injection is performed according to the operating state of the engine 1.

Next, how the air-fuel ratio correction coefficient FAF used in step S130 changes will be described. The air-fuel ratio correction coefficient FAF is the output voltage VO of the oxygen concentration sensor 56.
It changes based on 2. Specifically, as shown in FIG. 6, the output voltage V of the oxygen concentration sensor 56 at time t1.
When O2 is equal to or higher than the threshold level (0.45 [V]), that is, in the rich state, the air-fuel ratio correction coefficient FAF becomes a value dropped by RSL stepwise. After that, the air-fuel ratio correction coefficient FAF gradually decreases by the amount indicated by the integrated amount KIL.

On the other hand, when the output voltage VO2 becomes smaller than 0.45 [V] (time t2), the air-fuel ratio correction coefficient FAF becomes a value stepped up by RSR in a stepwise manner, and thereafter is shown by the integral amount KIR. Gradually increase in size. As a result, the fuel injection amount TAU is adjusted and the air-fuel ratio is balanced before and after the stoichiometric air-fuel ratio. The air-fuel ratio correction coefficient FAF is guarded with the maximum value Fmax and the minimum value Fmin in consideration of malfunction of the oxygen concentration sensor 56, and the fuel is within the range of the maximum value Fmax and the minimum value Fmin. The injection amount TAU is corrected.

Next, the sub-throttle target opening degree calculation processing routine executed by the CPU 70a of the ECU 70 will be described with reference to FIG. This processing routine is
The target opening TT2 of the sub-throttle valve 5 (hereinafter referred to as the sub-throttle target opening) is calculated, and is executed by interruption every predetermined time, for example, every 8 msec.

When the processing is started, the CPU 70a first detects the A by the first throttle position sensor 51.
The opening (main throttle opening) T1 of the main throttle valve 4 A / D converted by the / D converter 70e is read (step S200). Next, a process of reading the rotation speed Ne detected by the rotation speed sensor 50 and input through the input processing circuit 70f from the RAM 70c is executed (step S210).

Subsequently, the main throttle opening T1
Then, the sub-throttle target opening TT2 is obtained based on the rotation speed Ne. Specifically, the main throttle opening T1
And each value of the rotation speed Ne and the sub-throttle target opening T
A map showing the correlation with T2 is prepared in advance in the ROM 70b, and the main throttle opening T1 and the rotational speed Ne read in steps S200 and S210 are compared with the map A to obtain the sub-throttle target opening TT2. After that, the process returns to "return" and the process is terminated. According to the sub-throttle target opening calculation routine having such a configuration, the opening of the sub-throttle valve 5 is controlled non-linearly. Therefore, the sub-throttle valve 5 has a so-called electronic throttle valve.

Next, the target opening degree limiting processing routine executed by the CPU 70a of the ECU 70 will be described with reference to FIG. This processing routine limits the size of the sub-throttle target opening degree TT2 calculated by the above-mentioned sub-throttle target opening degree calculation routine.
For example, it is executed by interruption every 128 msec.

When the processing is started, the CPU 70a first detects the A by the first throttle position sensor 51.
The main throttle opening T1 A / D converted by the / D converter 70e is read (step S300). Next, the sub-throttle target opening TT2 calculated in the above-mentioned sub-throttle valve opening control processing routine is set to RA
It is read from M70c (step S310).

Subsequently, based on the main throttle opening T1 read in step S300, the lower limit value T2min of the opening of the sub throttle valve 5 (sub throttle opening).
Ask for. Specifically, a map A indicating the correlation between the main throttle opening T1 and the lower limit value T2min of the sub throttle opening is stored in advance in the ROM 70b.
Main throttle opening T read in step S300
1 is compared with the map A to obtain the lower limit value T2min.

Here, the lower limit value T2 of the sub throttle opening
The min will be described in detail. This lower limit value T2min
Shows a limit at which the negative pressure in the intake passage 2 rises and the amount of fuel vapor from the canister 22 becomes excessive when the sub-throttle valve 5 is further closed. The excess amount of fuel vapor here means that the intake amount of the fuel vapor causes a large change in the air-fuel ratio and the air-fuel ratio correction coefficient FAF sticks to the minimum value Fmin. This is a state in which the fuel ratio cannot be corrected sufficiently.

In this embodiment, according to various dimensions such as the diameter of the purge pipe 21, the purge pipe 21 with respect to the intake amount of the intake passage 2
It has been known in advance that when the purge rate, which is the flow rate, exceeds 1 [%], the above-described excess amount of the fuel vapor amount results. Therefore, the relationship between the main throttle opening T1 and the sub-throttle opening T2 such that the purge rate exceeds 1 [%] is obtained in advance, and the fuel vapor amount is calculated based on the value of the sub-throttle opening T2 with respect to the main throttle opening T1. Has set the judgment line that becomes an excessive state. That is, as shown in FIG. 9, the correlation between both throttle openings T1 and T2 and the purge rate at that time is experimentally measured in advance, and the purge rate is 1.
In the figure, the boundary that becomes 0 is connected by a solid line, and the line shown by this solid line is defined as the lower limit value T2min.

On the other hand, when the main throttle opening T1 is fully closed or close to it, there is a demand for completely shutting off the purge from the purge pipe 21 for idle stability and other reasons. Therefore, in FIG. 9, the boundary where the value of the main throttle opening T1 is small and the purge rate is 0 is connected by a broken line in the drawing, and the line of the lower limit value T2min is corrected by the line shown by this broken line. . Thus, as shown in FIG. 10, a map is created in which the lower limit value T2min of the sub-throttle opening corresponding to the main throttle opening T1 is set. This map corresponds to map A in step S320.

Returning to FIG. 8, when the lower limit value T2min based on the main throttle opening T1 is obtained in step S320, it is then determined in step S310 whether the sub-throttle target opening TT2 read is smaller than the lower limit value T2min. Perform (step S330). Where TT
When it is determined that 2 is smaller than the lower limit value T2min, the value of the lower limit value T2min is set to the sub-throttle target opening degree TT2.
(Step S340). On the other hand, when it is determined in step S330 that TT2 is equal to or more than the lower limit value T2min, the process of step S340 is skipped,
The value of the sub-throttle target opening TT2 remains unchanged.

Next, the sub throttle target opening TT
By outputting a control signal corresponding to 2 to the throttle actuator 6, processing for controlling the sub throttle valve 5 to the sub throttle target opening TT2 is performed (step S350). After that, the process returns to "return" to end this routine once.

According to this embodiment described above, when the target opening TT2 of the sub-throttle valve 5 falls below the lower limit value T2min of the sub-throttle opening determined from the opening T1 of the main throttle valve 4, the target opening TT2 TT2 is suppressed to the lower limit value T2min. Therefore, when the opening / closing control of the sub-throttle valve 5 is performed, the opening degree of the sub-throttle valve 5 is always limited to the opening degree that does not cause excessive supply of fuel vapor. Therefore, even when the opening / closing control of the sub-throttle valve 5 is always performed, the purge amount can be appropriately controlled, and as a result, the output of the engine 1 can be appropriately adjusted and the evaporative emission can be reduced. You can

In particular, when compared with the conventional one in which purging of the fuel vapor is prohibited when the opening of the sub-throttle valve is controlled to be closer to the opening than the opening of the main throttle valve, the operating range in which the purge control is performed. Since it can be expanded, the deterioration of evaporative emission can be surely eliminated.

Further, in this embodiment, when the value of the main throttle opening T1 is small, the lower limit value T2min of the sub-throttle opening is set to such a value that the purge rate takes the value 0. In the idle state, the fuel vapor is not purged from the canister 22. As a result, the stability of the rotation speed in the idle state can be improved.

Incidentally, in the prior art, purging in the idle state is prohibited by guarding the sub-throttle target opening TT2 when the idle switch of the first throttle position sensor 51 is in the on state. Then, when the idle switch is switched from the ON state to the OFF state, the sub-throttle valve 5 suddenly changes from the guard value to the nonlinear required opening value, so that the torque suddenly changes and adversely affects the drivability. There was a problem. On the other hand, in this embodiment, since the lower limit value T2min of the sub-throttle opening corresponding to the main throttle opening T1 is defined by the map A described above, switching from idle to normal running is performed by the vapor. A smooth transition can be achieved in terms of compatibility between suction and torque change.

The second embodiment of the present invention will be described below. In the second embodiment, in addition to the structure shown in the first embodiment, as shown in FIG. 11, the intake passage 2 and the canister 22 are provided.
A communication valve 25 is provided in the purge pipe 21 that connects with the communication valve 25, and the communication valve 25 is configured to be opened / closed by the ECU 70. The ECU 70 in this embodiment is
The communication valve 25 is opened / closed by executing the purge execution / inhibition processing routine shown in FIG. 12 instead of the target opening degree restriction processing routine shown in FIG. 8 in the first embodiment.

As shown in FIG. 12, the CPU of the ECU 70
When the processing is started, 70a first executes steps S400 to S having the same contents as steps S300 to S330 in FIG.
The process of 430 is executed. After that, when it is determined in step S430 that the sub-throttle target opening degree TT2 is smaller than the lower limit value T2min, the communication valve 25 is closed by outputting an OFF signal to the communication valve 25 (step S440). On the other hand, if it is determined in step S430 that TT2 is equal to or more than the lower limit value T2min, the communication valve 25 is opened by outputting an ON signal to the communication valve 25 (step S450). After executing step S440 or S450, the process returns to "return" to end this routine once.

According to the second embodiment described above, when the target opening TT2 of the sub-throttle valve 5 falls below the lower limit value T2min of the sub-throttle opening determined by the opening T1 of the main throttle valve 4, the communication valve 25 Is closed to prohibit purging of the fuel vapor from the canister 22. Therefore, even when the opening / closing control of the sub-throttle valve 5 is always performed, the purge amount can be appropriately controlled, and as a result, the output of the engine 1 can be appropriately adjusted as in the first embodiment. At the same time, the evaporative emission can be reduced, and further, the idle stability can be improved.

Another aspect of the present invention which replaces the first and second embodiments will be described below. In the first and second embodiments, the lower limit value T2mi of the sub throttle opening is set.
n is a determination line that causes an excessive fuel vapor amount (see FIG. 9).
This is determined from the middle and solid lines), but this determination line changes based on the minimum value Fmin of the air-fuel ratio correction coefficient FAF as described above. From this, when the minimum value Fmin shifts to the smaller side, it can be set to a determination line on the excess side of the determination line used in both examples, where the purge rate is 1 [%]. Therefore, the operating range in which the purge control is performed can be further expanded, and the evaporative emission can be further reduced.

Further, in both of the above-mentioned embodiments, the lower limit value T2mi of the sub-throttle opening that causes the fuel vapor amount to become excessive.
Although the minimum value Fmin of the air-fuel ratio correction coefficient FAF has been taken as a factor for determining n, any lower limit value T2min can be used as long as it indicates a limit that makes the fuel vapor amount excessive. For example, the minimum injection time that can be executed by the duty control of the fuel injection valve 8 may be used.

Further, in both of the above embodiments, the purge pipe (negative pressure introducing port) 21 is opened in the intake passage 2 between the main throttle valve 4 and the sub throttle valve 5, and the fuel vapor from the canister 22 is opened. Although it was configured to lead the inside of the intake passage from the section, instead of this, a negative pressure introducing port of the exhaust gas recirculation device (EGR) is opened in the intake passage 2 between the throttle valves 4 and 5, and the negative pressure is introduced. By driving the EGR valve with negative pressure from the port, EGR
Alternatively, the exhaust gas recirculated in step 1 may be introduced into the intake passage. In such a configuration, the condition for avoiding excessive supply of exhaust gas is stored in advance in the map as the lower limit value of the opening degree of the sub throttle valve 5 which is determined according to the opening degree T1 of the main throttle valve 4, and the map is used to The opening of the throttle valve 5 may be limited. Further, the lower limit value stored in this map may be set to a value on the most closed side where negative pressure is not applied to the negative pressure introduction port when the main throttle valve 4 is fully closed. It is possible to prevent the supply of EGR gas in

The negative pressure from the negative pressure introducing port causes E
The configuration for driving the GR valve may be a configuration for directly driving the EGR valve with the negative pressure, but instead of this,
It may be driven indirectly. That is, the negative pressure introduction port is connected to the diaphragm chamber of the negative pressure control valve for controlling the negative pressure of the intake pipe applied to the diaphragm chamber of the EGR valve, and the negative pressure control valve is opened and closed by the negative pressure from the negative pressure introduction port. However, the EGR valve may be driven by the negative pressure transmitted from the negative pressure control valve.

The embodiments of the present invention have been described above.
The invention is in no way limited to these examples. For example, instead of the configuration in which the opening is determined based on the main throttle opening T1 and the rotational speed Ne as the second throttle valve control means, the opening of the second throttle valve is controlled to suppress the output torque of the engine 1 when an acceleration slip occurs. Of course, the present invention can be implemented in various modes without departing from the scope of the invention.

[0050]

As described above, in the first internal combustion engine control apparatus of the present invention, when the opening / closing control of the second throttle valve is performed, the opening of the second throttle valve does not cause an excessive supply of fuel vapor. It is limited to such an opening.
Therefore, even when the opportunity to control the opening and closing of the second throttle valve increases, the purge amount can be appropriately controlled, and as a result, the output of the internal combustion engine can be appropriately adjusted and the evaporative emission can be reduced. You can In particular,
When the opening of the second throttle valve is controlled to be closer to the closing side than the opening of the first throttle valve, the operating range for performing the purge control is expanded when compared with the conventional one that prohibits purging of the fuel vapor. Therefore, the deterioration of the evaporative emission can be surely eliminated.

In the second internal combustion engine control apparatus of the present invention, when the opening / closing control of the second throttle valve is performed and the opening of the second throttle valve becomes an opening that causes excessive supply of fuel vapor, The supply of fuel vapor is prohibited. Therefore, even when the opportunity to control the opening and closing of the second throttle valve increases, the purge amount can be appropriately controlled. As a result, the output of the internal combustion engine can be output similarly to the first internal combustion engine control device. It is possible to reduce evaporative emission with appropriate adjustment of.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a basic configuration of a first configuration of the present invention.

FIG. 2 is a block diagram illustrating a basic configuration of a second configuration of the present invention.

FIG. 3 is a schematic configuration diagram showing an automobile engine as an internal combustion engine control device according to a first embodiment of the present invention and peripheral devices thereof.

FIG. 4 is a block diagram showing an electrical configuration of a control system centered on an ECU.

FIG. 5 is a flowchart showing a fuel injection control processing routine executed by the CPU of the ECU.

FIG. 6 is a timing chart showing an air-fuel ratio correction coefficient FAF that changes based on the output voltage VO2 of the oxygen concentration sensor.

FIG. 7 is a flowchart showing a sub-throttle throttle target opening calculation routine executed by the CPU.

FIG. 8 is a flowchart showing a target opening degree limiting processing routine which is also executed by the CPU.

FIG. 9 is a graph showing the relationship between the opening rates T1 and T2 of the main throttle valve and the sub throttle valve and the purge rate.

FIG. 10 is a graph showing a map A defining a relationship between a main throttle opening T1 and a sub throttle opening lower limit value T2min.

FIG. 11 is a schematic configuration diagram showing a configuration around a canister of an internal combustion engine control device which is a second embodiment of the present invention.

FIG. 12 is a flowchart showing a purge execution / prohibition processing routine executed by the CPU of the ECU of the second embodiment.

[Explanation of symbols]

 AC ... Accelerator pedal EG ... Internal combustion engine IN ... Intake passage TV1 ... First throttle valve TV2 ... Second throttle valve M1 ... Second throttle valve control means M2 ... Fuel tank M3 ... Fuel vapor collection means M4 ... Fuel vapor supply means M5 ... oversupply avoidance condition storage means M6 ... first throttle valve opening detection means M7 ... calculation means M8 ... control restriction means M18 ... fuel vapor supply prohibition means 1 ... engine 2 ... intake passage 3 ... accelerator pedal 4 ... main throttle valve 5 ... Sub-throttle valve 6 ... Throttle actuator 7 ... Surge tank 8 ... Fuel injection valve 21 ... Purge pipe 22 ... Canister 23 ... Steam pipe 24 ... Fuel tank 25 ... Communication valve 50 ... Rotation speed sensor 51 ... First throttle position sensor 52 ... Second throttle position sensor 4 ... Vacuum sensor 56 ... Oxygen concentration sensor 70 ... ECU 70a ... CPU 70c ... RAM FAF ... Air-fuel ratio correction coefficient Ne ... Rotation speed Pm ... Intake pressure TAU ... Actual fuel injection amount T1 ... Main throttle opening T2 ... Sub throttle opening TT2 ... Sub throttle target opening degree T2min ... Lower limit value

Claims (2)

[Claims] 1. A first throttle valve interlocked with an accelerator pedal and a second throttle valve located upstream of the first throttle valve are provided in an intake passage of an internal combustion engine, and a second throttle valve control means is provided. An internal combustion engine control device that controls the opening of the second throttle valve to control the output of the internal combustion engine independently of the operation of the accelerator pedal, and temporarily controls the fuel vapor generated in a fuel tank. Fuel vapor collecting means for collecting, and fuel vapor supply means for guiding the collected fuel vapor into the intake passage between the first throttle valve and the second throttle valve by negative pressure in the intake passage. And a second throttle valve which determines a condition for avoiding excessive supply of fuel vapor by the fuel vapor supply means according to the opening degree of the first throttle valve. Stored in advance as a lower limit value of the opening of the valve, an excessive supply avoidance condition storage means, a first throttle valve opening detection means for detecting the opening degree of the first throttle valve, and a storage content of the excessive supply avoidance condition storage means. From the first
An opening lower limit value calculating means for obtaining a lower limit value of the opening of the second throttle valve based on the opening of the first throttle valve detected by the throttle valve opening detecting means, and an opening of the second throttle valve Is a lower limit value calculated by the opening lower limit value calculating means, and a control limiting means for limiting the control by the second throttle valve control means. 2. A first throttle valve interlocking with an accelerator pedal and a second throttle valve located upstream of the first throttle valve are provided in an intake passage of an internal combustion engine, and a second throttle valve control means is provided. An internal combustion engine control device that controls the opening of the second throttle valve to control the output of the internal combustion engine independently of the operation of the accelerator pedal, and temporarily controls the fuel vapor generated in a fuel tank. Fuel vapor collecting means for collecting, and fuel vapor supply means for guiding the collected fuel vapor into the intake passage between the first throttle valve and the second throttle valve by negative pressure in the intake passage. And a second throttle valve which determines a condition for avoiding excessive supply of fuel vapor by the fuel vapor supply means according to the opening degree of the first throttle valve. Stored in advance as a lower limit value of the opening of the valve, an excessive supply avoidance condition storage means, a first throttle valve opening detection means for detecting the opening degree of the first throttle valve, and a storage content of the excessive supply avoidance condition storage means. From the first
An opening lower limit value calculating means for obtaining a lower limit value of the opening of the second throttle valve based on the opening degree of the first throttle valve detected by the throttle valve opening detecting means; and the second throttle valve control means. Fuel vapor supply prohibiting means for prohibiting the supply of fuel vapor by the fuel vapor supply means when the adjusted opening degree of the second throttle valve is smaller than the lower limit value obtained by the opening lower limit value calculating means. Internal combustion engine control device.