JPH1047039A - Method for activating catalyst of engine and catalyst activating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent worsening of operability during the use of heavy fuel as early activation of a catalyst through the increase of an exhaust gas temperature is performed during the cold starting of an engine. SOLUTION: An ignition timing control propriety deciding part 82 decides that a catalyst is in a non-activation state and an ignition timing is controllable when a cooling water temperature TW is within a given temperature range and a lapse time TS after the starting of an engine reaches in short of a given time. An ignition timing regulation part 84 effects setting such that an exhaust gas temperature is increased by delaying an ignition timing when the number Ne of revolutions of an engine exceeds the target number NeTG of revolutions and an ignition timing is caused to make access to a normal timing by advancing the ignition timing when the number Ne of revolutions of an engine is below the target number NeTG of revolutions. This constitution early activates a catalyst by the increase of an exhaust gas temperature during the use of standard fuel, and stabilizes a combustion state during the use of heavy fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst activation method and a catalyst activation device for an engine, in which the temperature of an exhaust gas is increased at the time of a cold start in which the temperature of an engine cooling water is low to activate the catalyst early.

[0002]

2. Description of the Related Art In general, a catalyst such as a three-way catalyst is provided in an exhaust passage of an engine, and the catalyst removes CO, HC, NOX and the like in exhaust gas. This catalyst has a property that it becomes activated to exhibit a purification performance for purifying HC and the like when the activation temperature is higher than a predetermined activation temperature, and becomes inactive when the activation temperature is lower than the activation temperature so that the purification performance is not exhibited. Therefore, during a cold start (cold start), the catalyst temperature is low and the catalyst is in an inactive state, so that HC and the like in the exhaust gas cannot be removed, and the exhaust emission deteriorates. For this reason, conventionally, during a cold start, the ignition timing during idling is retarded (retarded) from the normal ignition timing to increase the exhaust gas temperature, and the catalyst is heated by the high-temperature exhaust gas, thereby prematurely activating the catalyst. There has been proposed a method for achieving such a situation.

On the other hand, engine fuel mainly represented by gasoline includes a light standard fuel and a heavy fuel, and the volatility of the heavy fuel is lower than that of the standard fuel. Therefore, if the ignition timing retard amount for the early activation of the catalyst is set assuming the use of the standard fuel, if the actual fuel is heavy fuel, the combustion state deteriorates and misfire or torque There is a problem that drivability is reduced due to shortage or the like.

[0004] In order to prevent such deterioration in drivability when heavy fuel is used, for example, Japanese Unexamined Patent Publication No. 4-269376 discloses a means for measuring fuel heaviness. The ignition timing is corrected according to the quality.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 4-269 is disclosed.
The prior art described in Japanese Patent Publication No. 376 and 376 can cope with the difference in fuel properties, but the whole structure is complicated by the weight measurement means, and the manufacturing cost is increased. Also,
When an abnormality, an excessive error, or the like occurs in the determination result of the degree of heavyness, it becomes difficult to set an appropriate ignition timing according to actual fuel properties.

SUMMARY OF THE INVENTION The present invention has been made in view of the above various problems, and has as its object to provide a catalyst having a simple structure irrespective of the property of fuel and having a simple structure capable of promoting early activation of the catalyst. An object of the present invention is to provide an activation method and a catalyst activation device.

[0007]

According to a first aspect of the present invention, there is provided a method for activating a catalyst for an engine which determines whether or not a catalyst is in an inactive state and a state in which ignition timing control is to be performed during idling. In the case of an affirmative determination, in a rotation speed region where the engine rotation speed is equal to or higher than a predetermined target rotation speed, the ignition timing is retarded from the normal ignition timing, and the rotation speed lower than the predetermined target rotation speed is reduced. In several regions, the ignition timing is advanced to approach the normal ignition timing.

Here, when a light standard fuel is used as the fuel, the combustion proceeds well even if the ignition timing is delayed as described above, so that the engine speed immediately after the start is equal to or higher than a predetermined target speed. Is held. Then, the exhaust gas temperature rises due to the retardation of the ignition timing, and the catalyst is heated by the high-temperature exhaust gas, and the activation of the catalyst is promoted.
Here, the “target rotation speed” is set in advance as an optimum rotation speed in consideration of drivability, fuel efficiency, and exhaust emission from the cooling water temperature and the time after starting.

On the other hand, when a heavy fuel having low volatility is used, particularly in the case of a cold start of an engine, the fuel has a property that it is difficult to vaporize and the ignition of the air-fuel mixture is delayed.
Therefore, if the ignition timing is delayed at the time of the cold start, the combustion state deteriorates and the rotation speed decreases. Therefore, when the engine speed falls below the target speed due to the deterioration of the combustion state, it is determined that the heavy fuel is being used, and the ignition timing is advanced to control the ignition timing to return to the normal ignition timing.

[0010] The adjustment to advance the normal ignition timing improves the combustion state, and the engine speed once stabilizes at a speed lower than the target speed. Then, as the engine warms up, the engine speed increases to near the target speed. When the standard fuel and the heavy fuel are mixed, the engine speed temporarily settles at an intermediate speed between the target speed at which the standard fuel is stabilized and the speed at which the heavy fuel is stabilized. Thereafter, as the warm-up progresses, the rotation speed approaches the target rotation speed.

According to a second aspect of the invention, there is provided a method for activating a catalyst of an engine, wherein the determination in the ignition timing control availability determination step is performed before the time after starting the engine reaches a predetermined time and the engine coolant temperature is within a predetermined temperature range. If the determination is affirmative, it is determined that ignition timing control should be performed. That is, unless the time after the engine start is within the predetermined time and the engine coolant temperature is not within the predetermined range, the catalyst is not determined to be in the inactive state, and even if the catalyst is in the inactive state. It is not determined that the ignition timing should be retarded.

Therefore, even when the standard fuel is used, the ignition timing is not retarded when the cooling water temperature is extremely low outside the predetermined range. Therefore, it is possible to prevent the ignition timing from being retarded and the drivability from being deteriorated at an extremely low temperature at which even the standard fuel is unlikely to vaporize.

Further, after a lapse of a predetermined time from the start of the engine, since the catalyst temperature has already risen to the activation temperature or near the activation temperature due to the exhaust gas, it is limited to before the lapse of the predetermined time. Further, since there is a time delay between the rise in the catalyst temperature and the rise in the cooling water temperature, the cooling water temperature may fall within a predetermined range even when the catalyst temperature increases. Therefore, after a predetermined time has elapsed after the engine has been started, the ignition timing retard control is stopped, whereby unnecessary ignition timing retard can be eliminated to prevent deterioration of fuel efficiency.

According to a third aspect of the present invention, there is provided a method for activating a catalyst of an engine in a case where it is determined that ignition timing control should be performed in an ignition timing control availability determination step. The valve opening in the open loop of the idle speed control valve is made larger than the normal opening, and the valve opening is made smaller in the rotation speed region below the target rotation speed to reduce the valve opening in the normal open loop. The valve opening setting process at the time of the open loop to approach the value is performed.

Thus, when the ignition timing is to be retarded and the engine speed is equal to or higher than the target speed, the opening of the idle speed control valve in the open loop is increased, and the intake air is increased. The amount increases.
Here, when the engine speed is equal to or higher than the target speed, the ignition timing is retarded. Therefore, even if the intake air amount increases, the engine speed does not increase rapidly and is maintained near the target speed. Is done. Therefore, when the standard fuel is used, in addition to the effect of increasing the exhaust gas temperature by retarding the ignition timing, the effect of increasing the exhaust gas temperature by increasing the intake air amount can be obtained, and the catalyst can be activated earlier. it can.

According to a fourth aspect of the present invention, when the ignition timing control availability determination step determines that the ignition timing should be retarded, the opening of the idle speed control valve in the proportional integral control is performed. There is provided a feedback loop valve opening setting step of making the control amount in the valve direction smaller than the control amount in the normal state.

When heavy fuel is used, the normal proportional-integral control increases the amount of intake air but decreases the amount of fuel vaporized. Accordingly, the proportion of fuel in the intake air relatively decreases, the air-fuel ratio becomes lean, and the combustion state deteriorates. Therefore, when shifting from the open loop control to the proportional integral control which is the closed loop control, by reducing either the proportional control or the integral control in the valve opening direction, or by reducing both the proportional control and the integral control. In addition, it is possible to prevent an excessive increase in the amount of intake air, thereby preventing a lean state.

According to a fifth aspect of the present invention, in the method for activating the catalyst of the engine, the ignition timing is set such that the engine speed is equal to or higher than the target speed if the catalyst is determined to be inactive by the active status determination. In a few regions, the ignition timing is set to a predetermined retarded ignition timing, and in a region where the engine speed falls below the target rotation speed by a predetermined speed range or more, a normal ignition timing is set, and the engine speed is set to the In a region lower than the target rotational speed but within the predetermined rotational speed range, an intermediate ignition timing obtained by interpolation correction from the retarded ignition timing and the normal ignition timing is set.

Thus, when the ignition timing shifts from the retarded ignition timing to the normal ignition timing, the ignition timing passes through an intermediate ignition timing. Therefore, a rapid change in the ignition timing can be prevented, and the hunting phenomenon can be prevented.

The catalyst activating devices of the respective engines according to claims 6, 7 and 8 are realized by implementing the method according to the above-described claims 1 to 5 as devices, and have substantially the same functions. is there.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings.

First, FIG. 1 shows a schematic overall configuration of an automobile engine device to which an engine catalyst activation device according to an embodiment of the present invention is applied. An intake passage 12 and an exhaust passage 14 communicate with the horizontally opposed engine body 10. On the upstream side of the intake passage 12, an intake chamber 16 is opened in front of the vehicle body (not shown).
The intake pipes 22 branching from the surge tank 20 correspond to the cylinders 18 at the downstream side of the cylinders 18, and the downstream ends of the intake pipes 22 communicate with the combustion chambers 2 through the intake ports 24.
It communicates with 6. On the other hand, the downstream side of the exhaust passage 14 is connected to a muffler 28 attached to the rear part of the vehicle body, and the upstream side of the exhaust passage 14 is connected to each combustion chamber 2 via each exhaust port 30.
An exhaust pipe 32 communicates with 6.

An air cleaner 3 for removing dust from the air is provided in the intake passage 12 in order from the upstream side.
4. An air flow meter 36 for detecting the intake air amount Q and a throttle valve 38 for controlling the intake air amount according to the depression amount of an accelerator pedal (not shown) are provided.
The intake valve 12 bypasses the throttle valve 38.
Idle speed control (hereinafter referred to as "I
An ISC valve 42 for adjusting the amount of intake air at the time of idling is provided in the middle of the passage 40 (referred to as “SC”). The ISC valve 42 is opened and closed by a duty ratio. The ISC valve 42 is controlled in an open loop for a fixed time immediately after the engine is started, and after a lapse of the fixed time, feedback control (proportional integration control) is performed as described later. I have. Further, on the downstream side of each intake pipe 22, an injector 44 is provided so as to be directed to the intake port 24, and each of the injectors 44 is provided with a fuel pump 46.
The fuel supplied under pressure via the fuel pipe 48 is atomized and injected.

On the other hand, a catalyst 50, such as a three-way catalyst, is interposed near the engine body 10 in the exhaust passage 14. An air-fuel ratio sensor for detecting the air-fuel ratio in the exhaust gas is provided upstream of the catalyst 50. O2 sensor 52 is provided.

The EGR passage 54, which has a smaller passage area than the intake pipe 22 and the exhaust pipe 32,
An EGR valve 56, which is driven by, for example, a stepping motor, is provided in the middle of the EGR passage 54 so as to communicate between the exhaust pipe 32 and a collection portion of the intake pipe 22.

The cylinder head 58 has a combustion chamber 26
A spark plug 60 is provided facing the inside of the combustion chamber 26. The spark plug 60 is powered by a high voltage supplied through an igniter 62 and an ignition coil 64.
Forcibly ignite the air-fuel mixture inside at a predetermined ignition timing.

In the figure, reference numeral 66 denotes a crank angle sensor for detecting the crank angle and the engine speed N.
Is a knock sensor that detects knocking of the engine body 10, 70 is a water temperature sensor that detects the temperature of cooling water, 72 is a cam angle sensor that detects the rotation angle of a cam shaft 74 provided near the cam shaft 74, and 76 is idling. An idle switch for detecting a state is shown.

As shown in FIG. 2, an engine control unit (hereinafter, simply referred to as "ECU") 78 for controlling the driving of each member and receiving a detection signal from each sensor receives the signal from each sensor. Input interface 78a, output interface 78b for outputting a drive control signal to each member, and CP as a main processing unit
The microcomputer system is configured as a microcomputer system in which a U78c, a ROM 78d for storing a control program and preset fixed data, a RAM 78e for storing a detection signal from each sensor and the like are interconnected by a bus line 78f.

Here, the start timer 80 connected to the input interface 78a measures the elapsed time from the start of the engine and can be grasped as "post-start time detecting means". The start timer 80 is constituted by a combination of a means for detecting engine start such as an ignition switch and an alternator and a timer. Although the start timer 80 can be realized inside the ECU 78, for convenience, FIG. 2 shows that the start timer 80 is provided outside the ECU 78.

The ECU 78 has, as an internal function of the CPU 78c, an active state determining section 82 for determining the active state of the catalyst 50 based on the cooling water temperature detected by the water temperature sensor 70 and the post-start time detected by the start timer 80. And the determination result of the activation state determination unit 82 and the crank angle sensor 66
And an ignition timing adjusting unit 84 for setting the ignition timing based on the detected engine speed.

Next, a functional block diagram of the first embodiment shown in FIG. 3 will be described. The detected water temperature TW from the water temperature sensor 70 and the post-start time TS from the start timer 80 are input to the active state determination unit 82. The active state determination unit 82 determines whether the detected water temperature TW is within a predetermined range or not, and determines whether the post-start time TS is within a predetermined time. And a post-start time determination unit 82b. Then, the determination result of the active state determination unit 82 is output to the ignition timing adjustment unit 84 as an on / off change of the flag F.

The ignition timing adjusting section 84 includes an engine speed N from the crank angle sensor 66 and an idle switch 76.
An igniter 62 is connected to the output side of the igniter 62. Further, the ignition timing adjustment unit 8
The ROM 78 stores two types of ignition timing tables used for setting and adjusting the ignition timing, that is, a normal ignition timing table 86 and a retard ignition timing table 88.
d, these table values are input via the bus line 78f.

These tables 86 and 88 are used for setting the ignition timing in the idling state, and are configured as one-dimensional tables in which the ignition timing is set for each engine speed. More specifically, as shown in FIG. 4, a normal ignition timing IGTN for obtaining an optimal ignition timing by advancing the ignition timing in accordance with an increase in the engine speed N is stored in the normal ignition timing table 86. Is RO
M78d. Further, in the retard ignition timing table 88, the ignition timing IG is retarded in the region above the target rotational speed NeTG, and in the region below the target rotational speed NeTG, the ignition timing IG approaches the normal ignition timing IGTN.
TR is stored in the ROM 78d.

Then, the ignition timing adjusting section 84 determines whether or not the engine is idling based on the on / off state of the idle switch 76.
a, a rotation speed determination unit 84b for determining whether or not the engine rotation speed N from the crank angle sensor 66 is equal to or higher than the target rotation speed NeTG, and a calculation for reading out each of the tables 86 and 88 to calculate and set the ignition timing. A portion 84c.

Next, the operation of this embodiment will be described with reference to FIGS. First, the flowchart of FIG. 5 shows the operation of the active state determination processing,
In step 201, the coolant temperature TW is detected by a signal from the coolant temperature sensor 70, and a post-start time TS, which is an elapsed time after the engine is started, is detected by a signal from the start timer 80.

In S202, it is determined whether or not the cooling water temperature TW falls within a "predetermined range" defined by a lower limit water temperature TW1 and an upper limit water temperature TW2. Here, the lower limit water temperature TW1 is set to, for example, 0 ° C., and the upper limit water temperature TW2 is set to, for example, 60 ° C. Cooling water temperature TW
Is within the range of TW1 to TW2 (YES)
Moves to S203 as a cold start.

In S203, it is determined whether or not the post-start time TS detected by the start timer 80 has reached a reference time TS1 as a "predetermined time" set to, for example, about 40 seconds. When the post-start time TS has not reached the reference time TS1 (YES), the process proceeds to S204 because the ignition timing needs to be retarded immediately after the start or the like.

In S204, "1" is set to a flag F indicating whether or not ignition timing retard control can be performed, and a result of determination that ignition timing retard control is necessary is stored. On the other hand, if it is determined in S202 that the cooling water temperature TW is not within the range of TW1 to TW2 (NO), the ignition timing retard control is unnecessary (the catalyst is already active) or should be avoided ( Cryogenic). If it is determined in S202 that the post-start time TS exceeds the reference time TS1 (NO), it means that the ignition timing is not required to be retarded. Therefore, in the case of NO determinations in S202 and S203, the flag F is set to "0" in S204 because the retard control of the ignition timing is not required.

Next, a method of setting the ignition timing will be described with reference to the flowchart shown in FIG. First, S3
In 01, the state of the idle switch 76 is read to determine whether or not the vehicle is in the idling state. If the vehicle is in the idling state (YES), the flow proceeds to S302.

In step S302, the engine speed Ne is detected by the crank angle sensor 66.
The state of the flag F is determined, and it is determined whether the flag F is set to “1”. When the flag F is set to “1” by the activation state determination processing described above with reference to FIG. 5 (YES), in S304, the engine speed Ne is equal to or higher than the predetermined target speed NeTG shown in FIG. It is determined whether or not.

When it is determined in S303 that the engine speed Ne is equal to or higher than the target speed NeTG (YES),
Since it is possible to control the ignition timing to be retarded, the process proceeds to S305, and refers to the retard timing ignition timing table 88, and proceeds to S30.
At 6, the retard ignition timing IGTR is set as the ignition timing IGT, as shown by the solid line in FIG. Since each ignition plug 60 is ignited in accordance with the ignition timing IGTR at this retard, the explosion combustion timing is delayed and the exhaust gas temperature rises,
The catalyst 50 is quickly heated by the high-temperature exhaust gas.

On the other hand, at S304, the engine speed Ne
Is determined to be lower than the target rotation speed NeTG (NO), in S307, whether or not the engine rotation speed Ne is lower than the target rotation speed NeTG by a predetermined rotation speed ΔNe or more, in other words, As shown in FIG. 4, whether the engine speed is within the range of NeL to NeTG (N
e <NeTG−ΔNe) is determined. Engine speed N
If e is lower than the target rotation speed NeTG by a predetermined rotation speed ΔNe or more (YES), it is considered that heavy fuel is used and the rotation speed decreases. Then, S308
The flag F is reset (F ← 0) to indicate that the ignition timing retard control is no longer necessary.

Next, in S309, the normal ignition timing IGTN shown by the dotted line in FIG. 4 is set as the ignition timing IGT in S310 with reference to the ordinary ignition timing table 86. As a result, each ignition plug 60 ignites according to the ignition timing IGTN during normal idling,
The ignition timing is earlier than the ignition timing IGTR at the retard time, and the combustion state is stabilized. Accordingly, the rotation speed is stabilized at a rotation speed lower than the target rotation speed NeTG, and approaches the target rotation speed NeTG as the warm-up progresses.

On the other hand, at S307, the engine speed N
When e is lower than the target rotational speed NeTG but does not decrease by more than ΔNe (NO), that is, it is more preferable to use an intermediate ignition timing between the normal ignition timing IGTN and the retard ignition timing IGTR. Is the case. Therefore, the normal ignition timing table 8 in S311
6 and the retard time ignition timing table 88, and
In step 12, based on the ignition timings IGTN and IGTR, the engine speed Ne, and the like, interpolation correction is performed as shown in the following equation 1.

IGT = IGTR + ｛(IGTN-IGT)
R) · (NeTG−Ne)｝ / ΔNe Equation 1 That is, if the ignition timing IGTR is suddenly switched from the retard ignition timing IGTR to the normal ignition timing IGTN, a hunting phenomenon may occur. Therefore, even if the rotation speed falls below the target rotation speed NeTG, the interpolation correction is performed immediately without using the normal ignition timing IGTN.

On the other hand, if it is determined in step S303 that the flag F has been reset (F ← 0) (NO), the process proceeds to step S3.
09, S310, ignition of the air-fuel mixture is performed at the normal ignition timing IGTN.

According to the present embodiment having such an operation, the following effects can be obtained. First, it is determined whether or not the catalyst 50 is in an inactive state and a state in which ignition timing control should be performed. If the result is affirmative (F = 1), the engine speed is equal to or higher than a predetermined target speed NeTG. In the region (Ne ≧ NeTG), the ignition timing is retarded from the normal ignition timing (IGT
← IGTR), in a region (Ne <NeTG) below a predetermined target rotational speed NeTG, the ignition timing is advanced to approach the normal ignition timing (IGTN). Therefore, when the standard fuel is used, the ignition is performed as it is. Catalyst 5
An early activation of 0 is realized. When heavy fuel is used, it is possible to avoid the above-described decrease in the rotational speed, that is, the deterioration of the combustion state, to secure good combustion performance, and to prevent the deterioration of drivability.

Secondly, if the engine cooling water temperature TW is within the predetermined range TW1 to TW2 before the time TS after engine start reaches the predetermined reference time TS1, it is determined that the catalyst 50 is in an inactive state. Therefore, it is possible to prevent unnecessary ignition timing retard control from being performed.

That is, the cooling water temperature TW is lower than the lower limit water temperature TW1.
At extremely low temperatures below, it becomes difficult to vaporize not only heavy fuel but also light standard fuel. Therefore, when the ignition timing is retarded at such extremely low temperatures, misfire or the like may occur, and the drivability may be deteriorated. Further, the time TS after the engine is started is equal to a predetermined reference time T.
After the passage of S1, it is considered that the catalyst temperature has increased to near the activation temperature due to the exhaust gas during that time. Therefore, even if the ignition timing is retarded after the start time TS exceeds the reference time TS1, the effect of increasing the catalyst temperature obtained is small, and unburned HC increases, and the fuel efficiency may deteriorate. There is.

Therefore, according to the present invention, (1) the post-start time TS does not exceed the reference time TS1, and (2) the cooling water temperature TW is between the lower limit water temperature TW1 and the upper limit water temperature TW2. By setting the two conditions as AND conditions and preventing unnecessary retard control of the ignition timing beforehand, deterioration in drivability and fuel efficiency is prevented.

Third, when it is determined that the catalyst 50 is in an inactive state, the engine speed Ne is reduced to the target engine speed N.
The ignition timing is set to the retard ignition timing IGTR in a region equal to or higher than eTG (N ≧ NeTG), and in a region in which the engine speed Ne is lower than the target speed NeTG by a predetermined speed ΔNe or more (N <NeTG−ΔNe), it is normal. The ignition timing is set to IGTN, and the engine rotation speed Ne is lower than the target rotation speed NeTG but is not lower than the predetermined rotation speed ΔNe or more (N
eTG-ΔNe ≦ N <NeTG), the ignition timing I at the retard
The intermediate ignition timing (Equation 1) obtained by interpolation correction from the GTR and the normal ignition timing IGTN is set. Thus, the ignition timing can be shifted from the retard ignition timing IGTR to the normal ignition timing IGTN via an intermediate ignition timing. Therefore, it is possible to prevent a sudden change in the ignition timing and prevent the hunting phenomenon.

Next, the second embodiment of the present invention will be described with reference to FIGS.
An embodiment will be described. In the following embodiments, the same elements as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted. FIG. 7 is a functional block diagram of the catalyst activation device for the engine according to the present embodiment. The feature of the present embodiment is that, in cold start, in addition to the ignition timing retard control, the ISC valve 42 valve The point is to adjust the opening.

That is, the valve opening adjuster 90 to which the determination result from the activation state determiner 82 is input adjusts the valve opening of the ISC valve 42 immediately after the start to further increase the exhaust gas temperature. is there. A crank angle sensor 66 and an idle switch 76 are provided on the input side of the valve opening
A water temperature sensor 70 (the connection state of the water temperature sensor 70 is omitted) is connected, and an ISC valve 42 is connected to an output side of the valve opening adjustment unit 90.

The valve opening adjusting section 90 includes a normal valve opening table 92 used during a normal open loop and a retard opening time used by the ignition timing adjusting section 84 to execute the ignition timing retard control. Valve opening table 9
4 are stored in the ROM 78d in advance, and these table values are input via the bus line 78f. FIG.
As shown in FIG.
Represents the valve opening at the time of engine start, that is, the valve opening at the time of open loop control, for each cooling water temperature TW.
It is a dimension table. The retarded valve opening ISCR shown by the solid line in FIG. 3 is set to be larger than the normal valve opening ISCN also shown by the dotted line. Therefore, when the cooling water temperature TW is the same, the normal valve opening I
Since the retarded valve opening ISCR has a larger value than the SCN, setting the valve opening of the ISC valve 42 to the retarded valve opening ISCR increases the intake air amount during the open loop.

The valve opening setting section 90 determines whether or not the ISC valve 42 is controlled in an open loop under an idling state, and the engine speed Ne is equal to or higher than the target speed NeTG. A rotation speed determination unit 90b that determines whether the ISC valve 42 is operated and a calculation unit 90c that calculates the valve opening of the ISC valve 42 based on the tables 92 and 94 are provided.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. First, FIG. 9 is a flowchart of the valve opening setting process, which is executed in parallel with the ignition timing setting process shown in FIG. In S401, it is determined whether or not the vehicle is in an idling state based on the state of the idle switch 76, and if the vehicle is in an idling state (YES).
Proceeds to S402.

In S402, it is determined whether or not the ISC valve 42 is currently controlled in an open loop. That is, the valve opening of the ISC valve 42 is set to a predetermined value that is read according to the cooling water temperature TW for a certain time immediately after the engine is started, and after a certain time, feedback control is performed instead of open loop control. Is being done. Therefore, in S402, it is determined whether or not the ISC valve 42 is controlled in an open loop by referring to a control flag (not shown).

When the open loop control is being performed (YES),
In S403, the coolant temperature TW is detected, and in S404, the engine speed Ne is detected. Next, in S405, it is determined whether or not the flag F is set to "1", that is, whether or not ignition timing retard control is requested. When the ignition timing retard control is required (YE
In S), the process proceeds to S406, and it is determined whether or not the engine speed Ne is equal to or higher than the target speed NeTG.

If the determination is "YES", the ignition timing is retarded in steps S305 and S306 in the operation shown in FIG. In S407, the retarded valve opening ISCR corresponding to the cooling water temperature TW is read out with reference to the retarded valve opening table 94, and S4 is executed.
08, the read valve opening I at the time of the retard is read.
SCR is set as the valve opening ISCD of the ISC valve 42.

As a result, the ISC valve 42 opens more than usual, and the amount of intake air increases. here,
Since the ignition timing is retarded in S306 by the ignition timing setting process shown in FIG. 6, even if the intake air amount increases, the engine speed Ne does not increase sharply, and the engine speed Ne becomes equal to the target engine speed Ne. It is controlled near several NeTG. Therefore, the synergistic effect of the retard of the ignition timing and the increase of the intake air amount enhances the effect of increasing the exhaust gas temperature.

On the other hand, when "NO" is determined in S406, the engine speed Ne is lower than the target speed NeTG. In S409, the engine speed Ne is further increased to a target speed NeTG equal to or more than a predetermined speed ΔNe.
Is determined. In this step S409, the engine speed Ne is changed from the target speed NeTG to the predetermined speed ΔNe.
If it is determined that the temperature is lower than the above (YES), that is, if misfire or the like due to heavy fuel is considered to have occurred, the normal valve opening degree table 92 is referred to in S410, and the normal valve opening is performed in S411. Degree ISCN IS
It is set as the valve opening ISCD of the C valve 42.

In step S409, the engine speed N
e is lower than the target rotation speed NeTG but is not lower than the predetermined rotation speed ΔNe (N
O), that is, if it is in the boundary area, S412
Reference is made to both the normal valve opening table 92 and the retard valve opening table 94. And S41
In 3, the interpolation correction according to the following equation 2 is performed in the same manner as in the above equation 1. ISCD = ISCR + {(ISCN−ISCR) · (NeTG−Ne)} / ΔNe (2) According to the present embodiment configured as described above, in addition to the first embodiment, Also exerts the effect of.

First, when it is determined that the catalyst 50 is in an inactive state, the engine speed Ne is reduced to the target speed Ne.
In the region above TG (Ne ≧ NeTG), the valve opening ISCD in the open loop of the ISC valve 42 is made larger than the valve opening ISCN in the normal open loop (ISCD).
← ISCR, ISCR> ISCN), engine speed N
Region where e is lower than the target rotation speed NeTG (Ne <NeTG)
Since the valve opening ISCD is made smaller so as to approach the valve opening ISCN during normal open loop,
In addition to the effect of increasing the exhaust gas temperature by retarding the ignition timing, the effect of increasing the exhaust gas temperature by increasing the amount of intake air can be obtained. Therefore, the catalyst 50 can be activated earlier by further raising the exhaust gas temperature at the time of cold start.

Second, an intermediate region where the engine speed Ne is lower than the target speed NeTG but does not decrease by a predetermined speed ΔNe or more (NeTG−ΔNe ≦ Ne <NeTG).
Since the intermediate valve opening is set based on the normal valve opening ISCN and the retard valve opening ISCR, the hunting phenomenon can be more effectively prevented in combination with the ignition timing interpolation correction processing. it can.

Next, a third embodiment of the present invention will be described with reference to FIGS. As shown in the functional block diagram of FIG. 10, the catalyst activating device for the engine according to the present embodiment, like the second embodiment shown in FIG. Unit 84 and a valve opening adjusting unit 10 for setting the valve opening of the ISC valve 42
0 in parallel.

The valve opening adjusting section 100 is provided with the second
Similarly to the valve opening adjusting section 90 described in the embodiment,
A control state determination unit 100a, a rotation speed determination unit 100b,
A normal operation valve opening degree table 9
2 and the retard valve opening table 94 are connected. The valve opening setting unit 100 executes a valve opening setting process shown in FIG. 9 during the open loop control of the ISC valve 42 at the time of cold start.

In addition to this, the valve opening setting section 100 of the present embodiment also controls the ISC valve 42 in cooperation with the ignition timing retard control even during the feedback control executed after the end of the open loop control. The valve opening is being set and adjusted. That is, when heavy fuel is used, the combustion becomes unstable due to low volatility, and the engine speed Ne is lower than the target speed NeTG. Therefore, the ignition timing is adjusted by the ignition timing adjustment unit 84 to the normal ignition timing IGT.
When N is set, the combustion state is stabilized. As a result, as shown on the upper left side of FIG. 11, the engine speed Ne when using heavy fuel gradually decreases, and settles at a speed N1 lower than the target speed NeTG.

On the other hand, during the period from the start to the elapse of the predetermined time t1, as described above, the ISC valve 42 is open-loop controlled at the valve opening ISCD corresponding to the cooling water temperature TW. After the predetermined time t1 has elapsed,
Feedback control is performed based on the engine speed Ne. This feedback control is proportional integral control (P
I control), the proportional control amount P in the valve opening increasing direction.
U, a proportional control PD in the valve opening decreasing direction, an integral control IU in the valve opening increasing direction, and an integral control ID in the valve opening decreasing direction. The computing unit 100c of the valve opening setting unit 100 first sets the valve opening during the open loop control according to the flowchart shown in FIG. 9, and then controls the valve opening during the feedback control as described later. It is supposed to.

Next, the operation of the present embodiment will be described with reference to FIG.
This will be described based on the flowchart shown in FIG. FIG.
Shows the operation of the valve opening setting process, which is executed after the valve opening setting process shown in FIG.

In step S501, the state of the idle switch 76 is read to determine whether the idle switch 76 is in the idling state. If it is in the idling state (YES), it is determined in S502 whether feedback control is being performed. If it is determined in S502 that the open loop control has been completed and the feedback control has been started (YES),
An engine speed Ne is detected by a crank angle sensor 66.

Next, in S504, it is determined whether or not the flag F is set to "1".
Then, it is determined whether or not the ignition timing retard control by the control unit 4 is required. When it is determined “YES” in S504, it means that retard control of the ignition timing is required, and in S505, the ISC valve 42 is determined in the PI control.
Control components PU, IU acting in the direction of increasing the valve opening
Is reduced from the normal PU and IU by reducing the respective gains. As a result, the valve opening of the ISC valve 42 during the feedback control becomes smaller than the valve opening during the normal feedback control, so that the intake air amount is reduced as compared with the normal operation.

In the case where heavy fuel is used, if the normal PI control is performed when the control is shifted to the feedback control, the air-fuel mixture becomes lean, the combustion state is deteriorated, and the drivability may be reduced. This is because heavy fuel is difficult to vaporize, so that the amount of fuel sucked into the combustion chamber 26 as an air-fuel mixture decreases, but on the other hand, the amount of intake air increases due to normal PI control. . Therefore, S
At 505, while the retard control of the ignition timing is requested, the control components PU, I acting in the opening direction of the ISC valve 42 are controlled.
U is made smaller than usual to suppress excessive leaning and stabilize the combustion state.

In the present embodiment configured as described above,
The same effects as those of the first and second embodiments can be obtained. In addition, in the present embodiment, the catalyst 5
0 is determined to be inactive, that is, when ignition timing retard control is required, the ISC valve 4
Since the control amount in the valve opening direction in the feedback control of Step 2 is made smaller than the control amount in the normal state, even when the feedback control is shifted, the mixture becomes lean and burns when heavy fuel with low volatility is used. It is possible to prevent the state from deteriorating and the drivability from lowering.

It should be noted that the present invention is not limited to the configurations of the above embodiments, and various modifications can be made within the scope of the invention. For example, in each of the above embodiments,
Although the case where the present invention is applied to a horizontally opposed engine has been exemplified, it is needless to say that the present invention is not limited to this and can be applied to other types of engines.

Further, regarding the determination of the active state, the catalyst 50
, A catalyst temperature sensor may be provided in the vicinity of, and the activation state may be determined based on the catalyst temperature. In this case, catalyst 5
This is advantageous in that an active state of 0 can be directly detected. Further, the idling state can be detected based on the throttle opening of the throttle valve 38.

Further, in each of the above-described embodiments, the case of preparing two types of tables, the normal time table and the retard time table, is illustrated. Instead, only the normal time table is prepared. A configuration is also possible in which the value read from the table at normal time is corrected and used as the value at retard. Further, in the third embodiment, the valve opening degree setting process during the open loop control and the valve opening degree setting process during the feedback control are described. Only the degree setting process may be executed.

In the third embodiment, the case where both the proportional control amount PU and the integral control amount IU in the valve opening direction are reduced as compared with the normal time is exemplified. However, the present invention is not limited to this. The configuration may be such that only one of the minute PU and the integral control IU is reduced. In this case, however, it is preferable to reduce the proportional control PU in the valve opening direction in terms of control response time.

[0078]

As described above, according to the catalyst activation method and the catalyst activation device of the engine according to the present invention, the ignition timing is retarded when the standard fuel is used during the cold start of the engine. By raising the exhaust gas temperature, the catalyst can be activated early. In addition, when heavy fuel is used, the combustion state at the time of starting can be stabilized to prevent deterioration in drivability and fuel efficiency.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an overall configuration of an engine device to which an embodiment of the present invention is applied.

FIG. 2 is a configuration explanatory diagram showing an internal configuration of an ECU.

FIG. 3 is a functional block diagram of the first embodiment.

FIG. 4 is a graph showing characteristics of an ignition timing at a normal time and an ignition timing at a retard time.

FIG. 5 is a flowchart illustrating an active state determination process.

FIG. 6 is a flowchart illustrating an ignition timing setting process.

FIG. 7 is a functional block diagram according to a second embodiment of the present invention.

FIG. 8 is a graph showing characteristics of the valve opening of the ISC valve during normal operation and the valve opening of the ISC valve during retard operation.

FIG. 9 is a flowchart illustrating a valve opening degree setting process executed during open loop control of the ISC valve.

FIG. 10 is a functional block diagram according to a third embodiment of the present invention.

FIG. 11 is a graph showing a change characteristic of an engine speed and a valve opening of an ISC valve when shifting from open loop control to feedback control.

FIG. 12 is a flowchart illustrating a valve opening degree setting process performed during feedback control of the ISC valve.

[Description of Signs] 10 Engine main body 42 ISC valve 62 Igniter 66 Crank angle sensor 70 Water temperature sensor 76 Idle switch 78 ECU 80 Start timer 82 Active state determination unit (Ignition timing control availability determination unit) 84 Ignition timing adjustment unit 86 Normal ignition Timing table 88 Retarding ignition timing table 90 Valve opening adjustment unit 92 Normal valve opening table 94 Retarding valve opening table 100 Valve opening adjustment unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location F02P 5/15 F02P 5/15 BEK

Claims (8)

[Claims] 1. A method for activating a catalyst in an engine, wherein the activation of a catalyst during idling is promoted by controlling an ignition timing, wherein an ignition for determining whether or not the catalyst is in an inactive state and the ignition timing control should be performed is performed. Timing control availability determination step, a rotation speed determination step of determining whether the engine rotation speed is equal to or higher than a predetermined target rotation speed, and, when it is determined that the ignition timing control is necessary, the engine rotation speed is determined. The ignition timing is retarded from a normal ignition timing in a rotation speed region equal to or higher than a predetermined target rotation speed of the engine, and the ignition timing is advanced in a rotation speed region lower than the predetermined target rotation speed. An ignition timing adjustment step of adjusting the ignition timing so as to approach the ignition timing of the engine. 2. The ignition timing control availability determining step determines that the ignition timing control is necessary when the time after engine start does not reach a predetermined time and the engine coolant temperature is within a predetermined range. 2. The method according to claim 1, wherein
3. The method for activating a catalyst of an engine according to claim 1. 3. The throttle valve is bypassed when it is determined in the ignition timing control availability determination step that the ignition timing control is to be performed, and when the engine speed is in a rotation speed region equal to or higher than the target rotation speed. The opening degree of the idle speed control valve provided in the open loop is made larger than the normal opening degree, and the valve opening degree is made smaller when the engine speed is in the rotation speed region below the target rotation speed. 3. The catalyst activation method for an engine according to claim 1, further comprising an open-loop valve opening setting step of approaching the normal open-loop valve opening. 4. When it is determined in the ignition timing control availability determination step that the ignition timing control should be performed, the control amount in the valve opening direction during the proportional integral control of the opening and closing of the idle speed control valve is set to a normal time. The method according to any one of claims 1 to 3, further comprising a feedback loop valve opening setting step of making the control amount smaller than the control amount. 5. An ignition timing adjusting step, wherein, when it is determined in the ignition timing control availability determination step that the ignition timing control is to be performed, the engine rotational speed is in a rotational speed region equal to or higher than the target rotational speed. An ignition timing is set to a predetermined retarded ignition timing, and in a region where the engine speed falls below the target speed by a predetermined speed range or more, a normal ignition timing is set, and the engine speed is set to the target speed. The ignition timing is set to an intermediate ignition timing obtained by interpolating and correcting the retarded ignition timing and the normal ignition timing in an area that falls below the predetermined rotation speed range but falls within the predetermined rotation speed range. 5. The method for activating a catalyst of an engine according to any one of claims 4 to 4. 6. A catalyst activation device for an engine for promoting activation of a catalyst during idling by controlling ignition timing, comprising: a start timer for measuring a time after the engine is started; and a time after the engine is started to reach a predetermined time. An ignition timing control availability determination means for determining that the catalyst is in an inactive state and to perform ignition timing control if the engine cooling water temperature is within a predetermined range beforehand; Rotation speed determining means for determining whether or not the rotation speed is equal to or more than the rotation speed; and if the ignition timing control determination unit determines that ignition timing control is necessary, the engine rotation speed is equal to or higher than the target rotation speed. When the ignition timing is retarded from the normal ignition timing when in the rotation speed range, the engine rotation speed is in the rotation speed range below the target rotation speed. Catalyst activation device for an engine, characterized by comprising, an ignition timing adjusting means close to the normal ignition timing by advancing the ignition timing. 7. When the ignition speed control is determined to be performed by an idle speed control valve provided bypassing a throttle valve and the ignition timing control availability determination means, the engine speed is reduced to the target engine speed. When the engine speed is higher than the normal speed when the idle speed control valve is in the open loop when the engine speed is lower than the target speed, the engine speed is lower than the target speed. 7. The catalyst activation of the engine according to claim 6, further comprising: an open-loop valve opening setting means for reducing the valve opening to approach the normal open-loop valve opening when the valve is closed. apparatus. 8. When the ignition timing control is determined to be necessary by the ignition timing control availability determination means, the control amount in the valve opening direction during the proportional-integral control of the opening and closing of the idle speed control valve is set to a normal time. 8. The catalyst activation device for an engine according to claim 6, further comprising a feedback loop valve opening setting means for making the opening smaller than the control amount of the engine.