JP2007285249A - Engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine control device preventing deterioration of drivability after restart by an automatic stop and start function due to influence of purge gas of an engine. <P>SOLUTION: The device is provided with: a canister 31; a purge flow rate control means 206; a purge concentration detection means 201 detecting purge concentration Nprg of purge gas introduced into the engine 1; the automatic stop and start control means 209 automatically stopping the engine when predetermined automatic stop conditions are satisfied and automatically starting the engine when predetermined automatic start conditions are satisfied after automatic stop; and an automatic stop inhibition means inhibiting automatic stop process by the automatic stop and start control means 209 when purge concentration Nprg is predetermined value or higher. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine control device having an automatic stop / start function for performing control so that an engine is automatically started after being automatically stopped.

  2. Description of the Related Art Conventionally, there has been proposed a control device having an automatic engine stop function for automatically starting an engine mounted on a vehicle and controlling the engine to automatically start when a predetermined automatic start condition is satisfied after the automatic stop. (For example, see Patent Document 1).

  The automatic stop start conditions of the control device represented by Patent Document 1 are mostly conditions that can be surely started at the time of restart after the automatic stop, and the operation behavior after the restart, particularly the influence of the vaporized gas. Is not considered.

  By the way, a technique for introducing a purge gas into an engine through a canister is generally known. The purge gas introduced into the engine is increasing year by year in order to minimize the leakage of transpiration gas in the fuel tank, and there is a concern that the exhaust gas of the installed vehicle may deteriorate or the drivability may deteriorate depending on the excessive increase in the purge gas flow rate or concentration. Is done.

  Therefore, in order to suppress such exhaust gas deterioration and drivability deterioration, as a technique for performing optimal purge control and fuel control based on the purge concentration, for example, as shown in Patent Document 2, an A / F feedback correction coefficient is used, and the purge gas A technique has also been proposed in which the air-fuel consumption is kept constant by adjusting the amount of introduction (see, for example, Patent Document 2).

On the other hand, the automatic stop device represented by Patent Document 1 often automatically stops in a completely warm-up state, that is, in a state where a large amount of transpiration gas is likely to be generated.
When the engine is automatically stopped with a large amount of transpiration gas generated, the purge gas cannot be discharged to the engine and the fuel is not consumed when the engine is stopped. Further, a large amount of purge gas is adsorbed to the canister. Will be.

  As described above, when a large amount of purge gas is adsorbed to the canister, the automatic start condition is established and restarted. When the purge introduction condition is established and the purge gas is introduced after the vehicle is operated, the automatic stop start is performed. Compared with the case where no is applied, a large amount of purge gas may be introduced, leading to deterioration of exhaust gas and drivability.

Japanese Patent No. 3454048 Japanese Patent Laid-Open No. 11-72049

  In the conventional engine control device, when the automatic stop / start function is applied, the automatic stop is often performed in a completely warmed-up state, so that a large amount of purge gas is adsorbed to the canister. When purge gas is introduced after startup, a large amount of purge gas is introduced, which causes a problem that exhaust gas and drivability deteriorate.

  The present invention has been made to solve the above-described problems, and prevents the purge gas from being excessively introduced when the purge gas is introduced after the restart from the automatic stop to prevent the exhaust gas and the drivability from being deteriorated. An object of the present invention is to obtain an engine control device that can optimize the fuel consumption reduction effect and emission reduction effect by the stop / start function.

  An engine control device according to the present invention is provided in a fuel supply system for an engine mounted on a vehicle, adsorbs evaporated fuel, receives a negative pressure generated in an intake system of the engine, and releases the evaporated fuel as a purge gas. A purge flow rate control means for controlling the purge flow rate of the purge gas introduced into the engine, a purge concentration detection means for detecting the purge concentration of the purge gas introduced into the engine, and the engine is automatically stopped when a predetermined automatic stop condition is satisfied. And an automatic stop start control means for automatically starting the engine when a predetermined automatic start condition is satisfied after the automatic stop, and when the purge concentration shows a predetermined value or more, the automatic stop start control means It further includes automatic stop prohibiting means for prohibiting automatic stop processing by

  According to the present invention, by limiting the automatic stop function based on the comparison between the purge concentration and a predetermined value, an excessively high concentration of the purge gas is introduced when the purge gas is introduced after the restart from the automatic stop. It is possible to prevent the drivability from deteriorating and to optimize the fuel consumption reduction effect and emission reduction effect by the automatic stop / start function.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIGS.
FIG. 1 is a block diagram showing a schematic configuration of an engine control apparatus according to Embodiment 1 of the present invention, and shows an apparatus having the aforementioned automatic stop / start function.

In FIG. 1, an engine 1 mounted on a vehicle is controlled by an ECU (electronic control unit) 5 having an automatic stop / start function.
The engine 1 includes a general starter 2 for starting, a motor generator (hereinafter abbreviated as “MG”) 3 via a belt 20, and a rotation sensor 12 that detects the rotational speed Ne of the engine 1. A water temperature sensor 13 for detecting the cooling water temperature Wt, an injector 14 for injecting fuel, and a canister 31 through a purge valve 30 are provided.

The MG 3 is driven by the inverter 4 and operates as a starter motor, and also operates as a generator as necessary.
That is, the MG 3 generates a starting rotational force separately from the starter 2, transmits the rotational force to the engine 1 via the belt 20, and is rotated via the belt 20 by the rotational force of the engine 1 to generate electric power. Do.
A battery 21 mounted on the vehicle stores electric power generated from the MG 3 and supplies battery voltage to the inverter 4 and the ECU 5.

  The canister 31 is provided in a fuel supply system for the engine 1 and adsorbs the evaporated fuel, receives a negative pressure generated in the intake system of the engine 1 when the purge valve 30 is opened, and separates the evaporated fuel as a purge gas to remove the evaporated system. To be introduced.

The ECU 5 is connected to the inverter 4 via the communication line 22 so as to be able to communicate with each other.
The ECU 5 includes not only the rotation sensor 12 and the water temperature sensor 13 but also an ignition key switch (hereinafter abbreviated as “IGSW”) 6 for starting / stopping the engine by a manual key operation, and a vehicle speed sensor 7 for detecting the vehicle speed Vs. An accelerator sensor 8 that detects the amount of accelerator depression, a shift position sensor 9 that detects the shift position of a transmission (not shown), a brake SW 10 that is turned on when a brake pedal (not shown) is depressed, and the engine 1 An O2 sensor 15 that detects the oxygen concentration in the exhaust system as air-fuel ratio A / F information and other various sensors 11 (including a crank angle sensor, an airflow sensor, etc.) are connected.

  The ECU 5 includes a purge concentration detection means 201 for detecting the purge concentration Nprg of the purge gas introduced into the engine 1, a purge flow rate control means 206 for controlling the purge valve 30, an injector control means 207 for controlling the injector 14, the starter 2, and An automatic stop / start determination unit 208 that determines the control condition of the inverter 4 and an automatic stop / start control unit 209 that controls the engine 1 according to the determination result of the automatic stop / start determination unit 208 are provided.

The detection information from the various sensors 6 to 13 and 15 includes operating state information necessary for executing the automatic stop / start control of the engine 1.
The ECU 5 executes various control calculations based on various sensor information, and calculates control amounts for various actuators such as the starter 2, the inverter 4, the injector 14, and the purge valve 30.

For example, the ECU 5 outputs an initial start command to the starter 2 to start the engine 1 when the IGSW 6 is started (from the OFF state to the ON state) by the vehicle driver.
Further, the purge flow rate control means 206 in the ECU 5 controls the opening and closing of the purge valve 30 according to the operating state of the engine 1 and removes it from the canister 31 and introduces it into the engine 1 as a purge flow rate Qprg (according to the purge valve 30 and the like). Control).

The automatic stop / start control means 209 in the ECU 5 automatically stops the engine 1 when a predetermined automatic stop condition (described later) is satisfied during operation, and when the predetermined automatic start condition is satisfied after the automatic stop. 1 is automatically restarted.
That is, the automatic stop / start control means 209 outputs an OFF signal to the injector control means 207 so as to cut the fuel supply to the engine 1 when the automatic stop condition of the engine 1 is satisfied during the operation of the engine 1. Is automatically stopped.

The automatic stop conditions of the engine 1 are, for example, the following five, and automatic stop is permitted when all of these conditions (a) to (e) are satisfied.
(A) Accelerator OFF (accelerator depression amount is “0”).
(B) The shift position is in the D (drive) range.
(C) Cooling water temperature Wt ≧ predetermined temperature.
(D) The vehicle speed Vs = 0.
(E) The brake SW10 is ON.

Note that the automatic stop prohibition condition of the engine 1 is that the purge concentration Nprg is a predetermined value or more.
That is, the automatic stop prohibiting means 210 (see FIG. 3 to be described later) in the automatic stop start determining means 208 is automatically based on the detected value of the purge concentration Nprg based on the F / B control value (A / F feedback correction coefficient Kfb). Determine stop / start conditions.

  Further, the automatic stop / start determination means 208 in the ECU 5 generates a restart command and sets the automatic stop / start control means 209 when a predetermined restart condition of the engine 1 is satisfied in a state where the engine 1 is automatically stopped. Make it work.

That is, the automatic stop / start control means 209 activates the starter 2 or the inverter 4 to restart the engine 1 when the restart condition is satisfied.
For example, when a start command is output from the automatic stop / start control means 209 to the inverter 4, the inverter 4 outputs a drive signal to the MG 3 to start the engine 1 in the automatic stop state.

The restart condition is, for example, that the brake SW10 is turned off.
Further, since the ECU 5 and the inverter 4 are connected via the communication line 22 so as to be able to communicate with each other, when the automatic stop / start control means 209 outputs a start command to the inverter 4, information in the inverter 4 is stored. Can be transmitted to the ECU 5 via the communication line 22.

The flowchart of FIG. 2 shows the automatic stop / start condition determination processing by the automatic stop / start determination means 208 (steps S101 to S105, S108, S109) and automatic stop prohibition processing (step S106), and the automatic stop / start control means 209 performs automatic processing. Stop / start processing (steps S107 and S110) is shown.
Further, the functional block diagram of FIG. 3 shows the configuration in the ECU 5 more specifically.

  In FIG. 3, the ECU 5 calculates a concentration correction coefficient in addition to the purge concentration detection means 201, purge flow rate control means 206, injector control means 207, automatic stop start determination means 208 and automatic stop start control means 209 shown in FIG. Means 202, correction coefficient determination means 203, purge rate control means 204, and A / F feedback correction coefficient setting means 205 are provided.

The automatic stop / start determining means 208 includes an automatic stop prohibiting means 210. The automatic stop prohibiting means 210 prohibits automatic stop processing by the automatic stop / start control means 209 when the purge concentration Nprg is equal to or higher than a predetermined value. To do.
It should be noted that the predetermined value serving as a comparison reference for the purge concentration Nprg is set to a value that does not adversely affect the exhaust gas and drivability in the operating state after the engine 1 is restarted.

The purge concentration detection unit 201 detects the purge concentration Nprg by an estimation calculation based on the fuel control value of the engine 1, and inputs the estimation calculation result to the automatic stop / start determination unit 208 and the concentration correction coefficient calculation unit 202.
The concentration correction coefficient calculation unit 202 calculates a concentration correction coefficient Kprg based on the purge concentration Nprg, and inputs the calculation result to the correction coefficient determination unit 203 and the injector control unit 207.

The correction coefficient determination unit 203 compares and determines the concentration correction coefficient Kprg with a predetermined determination threshold value, and inputs the determination result to the purge rate control unit 204.
The purge rate control unit 204 calculates a purge rate Rprg corresponding to the purge flow rate Qprg, and inputs the calculation result to the purge concentration detection unit 201, the purge flow rate control unit 206, and the concentration correction coefficient calculation unit 202.
The A / F feedback correction coefficient setting means 205 inputs the A / F feedback correction coefficient Kfb to the purge concentration detection means 201 and the injector control means 207.

The automatic stop / start determination process according to the first embodiment of the present invention shown in FIGS. 1 and 3 will be specifically described below with reference to the flowchart of FIG.
The processing routine of FIG. 2 shows an example of an automatic stop / start control routine of the engine 1 and is repeatedly executed in the ECU 5 at regular intervals.

  In FIG. 2, the automatic stop / start determination means 208 first executes signal input processing from the various sensors 6 to 13 and 15 (step S100), and the detection signal from the brake SW10 indicates the brake ON state (ie, brake Is determined) (step S101).

If it is determined in step S101 that the brake SW10 is in the OFF state (that is, NO), the process proceeds to determination step S108 described later.
On the other hand, if it is determined in step S101 that the brake SW 10 is in the ON state (that is, YES), then the detection signal from the accelerator sensor 8 indicates the accelerator OFF state (that is, the vehicle user's foot is separated from the accelerator). (Step S102).

If it is determined in step S102 that the accelerator is in the ON state (that is, NO), the process proceeds to determination step S108 described later.
On the other hand, if it is determined in step S102 that the accelerator is in an OFF state (that is, YES), whether or not the cooling water temperature Wt of the engine 1 detected by the water temperature sensor 13 indicates a predetermined temperature or higher (warm-up state). Is determined (step S103).

If it is determined in step S103 that Wt <predetermined temperature (that is, NO), the process proceeds to determination step S108 described later.
On the other hand, if it is determined in step S103 that Wt ≧ predetermined temperature (that is, YES), it is subsequently determined whether or not the shift position detected by the shift position sensor 9 indicates the D range (step S104).

If it is determined in step S104 that the shift position is not in the D range (that is, NO), the process proceeds to determination step S108 described later.
On the other hand, if it is determined in step S104 that the shift position is in the D range (that is, YES), then whether or not the vehicle speed Vs detected by the vehicle speed sensor 7 is “0” (vehicle stopped state). Is determined (step S105).

If it is determined in step S105 that Vs> 0 (that is, NO), the process proceeds to determination step S108 described later.
On the other hand, if it is determined in step S105 that Vs = 0 (that is, YES), then the automatic stop prohibiting means 210 in the automatic stop / start determining means 208 causes the purge concentration Nprg detected by the purge concentration detecting means 201 to continue. Is less than a predetermined value (step S106).

If it is determined in step S106 that Nprg ≧ 0 (that is, NO), the process proceeds to determination step S108 described later without executing the automatic stop process (step S107) of the engine 1.
On the other hand, if it is determined in step S106 that Nprg <predetermined value (that is, YES), the automatic stop / start control means 209 outputs a misfire command to the injector control means 207, and executes the automatic stop processing of the engine 1. (Step S107).

As described above, the predetermined value compared with the purge concentration Nprg is such that a large amount of purge gas is not discharged and does not adversely affect the exhaust gas and drivability in the operating state after the engine 1 is restarted. Such a value is preset.
That is, after restart after automatic stop (described later), automatic stop is permitted only when exhaust gas or drivability is not adversely affected by purge gas during vehicle travel.

As described above, in the determination process (steps S101 to S105) of the automatic stop start determination unit 208, the process proceeds to the determination process (step S106) of the automatic stop prohibition unit 210 only when all the determinations are “YES”. The automatic stop process (step S107) by the automatic stop / start control means 209 is executed only when it is determined “YES” in FIG.
On the other hand, if “NO” is determined in any of steps S101 to S106, the execution of the automatic stop process (step S107) is prohibited and the process skips to step S108.

Next, the routine proceeds to a restart determination routine (steps S108 and S109) by the automatic stop start determination means 208 after the automatic stop.
First, in step S108, it is determined whether or not the engine 1 is automatically stopped. If it is determined that the engine 1 is not automatically stopped (that is, NO), the processing routine of FIG. 2 is terminated.

  On the other hand, if it is determined in step S108 that the engine 1 is automatically stopped (that is, YES), it is subsequently determined whether or not the brake SW10 is in an OFF state (step S109), and the brake SW10 is turned on. If it is determined that the state is in the state (that is, NO), the processing routine of FIG. 2 is terminated.

On the other hand, if it is determined in step S109 that the brake SW 10 is in the OFF state (that is, YES), the automatic stop / start control means 209 activates the starter 2 or the inverter 4 and executes the automatic start process of the engine 1. (Step S110).
Thereafter, the process routine of FIG. 2 is exited and the process returns to the main routine.

As described above, according to the engine control apparatus of the first embodiment of the present invention, the predetermined automatic stop condition (steps S101 to S105) of the engine 1 is satisfied, and the purge concentration Nprg is less than the predetermined value (step S106). The engine 1 is automatically stopped only when) is indicated.
Further, after the automatic stop (step S108), control is performed so that the engine 1 is automatically started when a predetermined automatic start condition (step S109) is satisfied.

That is, when the purge concentration Nprg is equal to or greater than a predetermined value (the determination result of step S106 is “NO”), the execution of the automatic stop process is permitted even if a predetermined automatic stop condition (steps S101 to S105) is satisfied. It will never be done.
As a result, it is possible to prevent deterioration of exhaust gas and drivability due to the introduction of a large amount of purge gas after automatic start.

  Next, referring to the function block diagram of FIG. 3 together with FIG. 1, the automatic stop / start determination process according to the first embodiment of the present invention, the detection of the purge concentration Nprg, and the fuel control executed in relation thereto (A / F feedback control) will be specifically described with an example.

In FIG. 3, functional blocks mainly related to purge control are shown, and other functions are omitted.
The purge concentration detection means 201 does not use a special sensor for directly detecting the purge concentration Nprg, but based on various conventional sensors used for fuel control or purge control and information in the ECU 5. A description will be given assuming that the purge concentration Nprg is detected by estimation calculation.

  In the purge control according to the first embodiment of the present invention, the purge gas containing the evaporated fuel (gasoline vapor) separated from the canister 31 is basically introduced into the engine 1 by adjusting the flow rate by opening and closing the purge valve 30. Together with the fuel injected from 14, the fuel contributes to combustion.

Therefore, the ECU 5 includes a purge rate control unit 204 and a purge flow rate control unit 206 as purge control units that control the operation of the purge valve 30 to adjust the purge flow rate Qprg and thereby adjust the purge rate Rprg.
Further, the ECU 5 feedback-controls the fuel injection amount from the injector 14 and serves as an A / F feedback correction coefficient as air-fuel ratio control means for making the air-fuel ratio A / F of the air-fuel mixture supplied for combustion in the engine 1 constant. Setting means 205 and injector control means 207 are provided.

  Further, the ECU 5 includes the concentration correction coefficient calculation means 202 and the correction coefficient determination means 203 related to the purge concentration detection means 201 and the purge rate control means 204, and the automatic stop start determination means 208 and the automatic stop start control means 209 described above. I have.

  The purge concentration detection unit 201 includes a purge flow rate Qprg adjusted by the purge flow rate control unit 206 (or a purge rate Rprg set in advance based on the rotational speed Ne and the deposition efficiency Ev), and an air-fuel ratio in the injector control unit 207. Based on the A / F feedback correction coefficient Kfb used as the A / F feedback control amount, the purge concentration Nprg is estimated and calculated as described later.

  Based on the purge concentration Nprg estimated by the purge concentration detection unit 201 and the purge rate Rprg corresponding to the purge flow rate Qprg, the concentration correction coefficient calculation unit 202 performs feedback control of the air-fuel ratio A / F as will be described later. A concentration correction coefficient Kprg for the purge concentration Nprg to be used is obtained.

The correction coefficient determination unit 203 compares the density correction coefficient Kprg with the first determination threshold and the second determination threshold (limit value smaller than the first determination threshold).
The purge rate control unit 204 gradually increases the purge rate Rprg with a predetermined gain when the value of the concentration correction coefficient Kprg is larger than the first determination threshold according to the determination result of the correction coefficient determination unit 203.

Further, when the value of the concentration correction coefficient Kprg is equal to or lower than the first determination threshold value, the purge rate control unit 204 holds the purge rate Rprg at that time.
Further, when the value of the concentration correction coefficient Kprg is equal to or less than the second determination threshold value (limit value), the purge rate control unit 204 sets the purge rate Rprg to a predetermined value (specified value) as described later. Reset to.

On the other hand, the injector control means 207 performs feedback control so as to make the air-fuel ratio A / F of the air-fuel mixture provided for combustion in the engine 1 constant by adjusting the amount of fuel injected from the injector 14 as described above. .
In particular, the injector control means 207 adjusts the fuel injection amount for the engine 1 by variably setting the injector drive time Tinj corresponding to the fuel injection time from the injector 14.

  In addition, the injector control means 207, for the basic drive time Tb set to inject a predetermined amount of fuel from the injector 14, for example, the air-fuel ratio A / F monitored by the O2 sensor 15 and the target air-fuel ratio (for example, The air-fuel ratio A / F is made constant by multiplying the A / F feedback correction coefficient Kfb (= 0 to 1) as the control amount obtained in accordance with the deviation from the theoretical air-fuel ratio = 14.7). The injector drive time Tinj that is feedback-controlled is obtained.

  At this time, the injector control unit 207 multiplies the basic driving time Tb by a density correction coefficient Kprg (= 0 to 2) newly obtained by the density correction coefficient calculation unit 202, and other correction coefficients Tels ( = 0 to 1), when the purge gas is introduced, the injector drive time Tinj feedback-controlled so as to make the air-fuel ratio A / F constant is obtained to drive the injector 14, and the injector drive time An amount of fuel corresponding to Tinj is injected.

In other words, the injector control means 207 newly adds a concentration correction coefficient Kprg corresponding to the purge concentration Nprg of the purge gas introduced into the engine 1 as a parameter used for the air-fuel ratio A / F feedback control described above. The control of the fuel injection amount commensurate with the introduction of the purge gas is realized.
Here, the injector drive time Tinj is calculated as in the following equation (1).

  Tinj = Tb · (Klrn + Kfb) · Kprg · Tels + Td (1)

However, in Equation (1), Klrn is an A / F learning correction coefficient (Klrn = 0 to 1) learned from past feedback results, and Td is a dead time specific to the injector 14 required for the operation of the injector 14. is there.
The injector 14 is driven with the injector driving time Tinj obtained by the equation (1), thereby injecting an amount of fuel corrected by feedback control.

Next, the purge concentration Nprg estimation process by the purge concentration detection means 201 will be described.
First, the purge rate control unit 204 uses the purge flow rate Qprg controlled by the purge flow rate control unit 206 and the intake air amount Qa detected by the airflow sensor included in the various sensors 11 as shown in the following equation (2). The purge rate Rprg is calculated.

  Rprg = Qprg / Qa (2)

As a result, the purge concentration detection unit 201 determines the purge concentration Nprg based on the purge rate Rprg expressed by the equation (2) and the A / F feedback correction coefficient Kfb used by the injector control unit 207 as described later. Is estimated.
That is, when the purge gas is not introduced, the air-fuel ratio A / F (b) of the air-fuel mixture supplied to the engine 1 and used for combustion is expressed by the following equation (3) using the air density ρa. The

A / F (b) = air weight / fuel weight = (ρa · Qa) / {(ρa · Qa) /14.7} · Kfb · Kprg (3)

Note that “(Qa × ρa) /14.7” in Equation (3) is the amount of fuel injected from the injector 14 in order to set the air-fuel ratio A / F to the stoichiometric air-fuel ratio (= 14.7). .
is there.

The air-fuel ratio A / F of the air-fuel mixture in the engine 1 is basically obtained according to the intake air amount Qa introduced into the engine 1 and the fuel amount injected from the injector 14 as described above.
Here, the air-fuel ratio A / F (p) when the purge gas is introduced into the engine 1 is expressed by the following equation (4) using the gasoline density ρg.

A / F (p) = (weight of air + weight of air in purge gas) / (weight of fuel + weight of fuel in purge gas)
= {(Ρa · Qa) + ρa · (Qa · Rprg) · (1.0−Nprg)} / [{(ρa · Qa) /14.7} · Kfb · Kprg + ρg · (Qa · Rprg) · Nprg]
... (4)

However, in the formula (4), “1.0−Nprg” indicates the air concentration in the purge gas.
Further, when the air-fuel ratio A / F (p) represented by the equation (4) is arranged with respect to the air weight (= ρa · Qa), the following equation (5) is obtained using the specific gravity αg (= ρg / ρa) of gasoline vapor. ).

  A / F (p) = [1.0 + Rprg · (1.0−Nprg)] / [[Kfb · Kprg / 14.7] + Rprg · Nprg · αg] (5)

However, in the formula (5), the value of the specific gravity αg of the gasoline vapor is “2.49”, for example.
Therefore, if the air-fuel ratio A / F is controlled to the theoretical air-fuel ratio (= 14.7) that is the control target value, the control condition (correction coefficient) at that time is the following equation (6) with respect to the purge concentration Nprg: ) As long as the relationship is satisfied.

  14.7 = [1.0 + Rprg · (1.0−Nprg)] / [[Kfb · Kprg / 14.7] + Rprg · Nprg · 2.49] (6)

  Therefore, if the A / F feedback correction coefficient Kfb and concentration correction coefficient Kprg, which are obtained as control conditions for making the air-fuel ratio A / F constant, are calculated, and the purge rate Rprg obtained from the purge flow rate Qprg, respectively. According to these calculated values, the purge concentration Nprg can be estimated from the following equation (7) based on the equation (6).

  Nprg = [1.0 + Rprg−Kfb · Kprg] / [3.76 · Rprg] (7)

Here, if the purge gas is not introduced, the A / F feedback correction coefficient Kfb is about “1.0”.
On the other hand, during the introduction of the purge gas, every time the concentration correction coefficient Kprg is updated, the A / F feedback correction coefficient Kfb is controlled to approximately “1.0” so as not to impair the continuity of the fuel injection amount. The
Therefore, the density correction coefficient Kprg can be obtained as shown in the following equation (8), assuming that the A / F feedback correction coefficient Kfb = 1.0.

  Kprg = 1.0 + Rprg− (3.76 · Nprg · Rprg) (8)

  Also, when the concentration correction coefficient Kprg is given as an initial value (= 1.0) without the correction control of the fuel injection amount accompanying the introduction of the purge gas being executed at the time when the introduction of the purge gas is started, The purge concentration Nprg can be obtained by the following equation (9) from the A / F feedback correction coefficient Kfb at that time and the purge flow rate Qprg (purge rate Rprg) at which the introduction of the purge gas is started.

  Nprg = [1.0 + Rprg−Kfb] / [3.76 · Rprg] (9)

Based on the above viewpoint, the purge concentration detection means 201 purges the A / F feedback correction coefficient Kfb used for air-fuel ratio A / F feedback control and the purge gas introduced into the engine 1 via the purge valve 30. From the flow rate Qprg (purge rate Rprg), the purge concentration Nprg at that time is detected by estimation calculation.
Further, the concentration correction coefficient calculating means 202 is a control used for feedback control of the air-fuel ratio A / F by referring to a table, for example, according to the purge concentration Nprg estimated by the purge concentration detecting means 201 and the purge rate Rprg. A density correction coefficient Kprg as a parameter is obtained.

As described above, according to the first embodiment of the present invention, it is possible to estimate the purge concentration Nprg using information used for existing fuel control and purge control, and to detect the purge concentration Nprg. The purge concentration Nprg can be detected without using a sensor.
Therefore, the automatic stop start condition can be determined based on the detected value of the purge concentration Nprg, and the automatic stop start control can be executed.

The method for estimating the purge concentration Nprg according to the first embodiment is an example for estimating the purge concentration Nprg without using a special sensor, and does not depart from the gist that it can be applied to the automatic stop / start determination. If it is the estimation method of Nprg, it will not be limited to the said estimation method, You may use another control value.
Further, although the purge concentration Nprg is used for the determination of the automatic stop and start based on the detection value obtained by estimation, it goes without saying that a special sensor or the like may be separately used in order to detect the purge concentration Nprg more reliably.

It is a block diagram which shows schematic structure of the engine control apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the process sequence of the automatic stop start control by Embodiment 1 of this invention. It is a functional block diagram for demonstrating the detection process of the purge density | concentration by Embodiment 1 of this invention.

Explanation of symbols

  1 engine, 2 starter, 3 MG (motor generator), 4 inverter, 5 ECU, 6 ignition key SW, 7 vehicle speed sensor, 8 accelerator sensor, 9 shift position sensor, 10 brake SW, 11 other various sensors, 14 injector, 15 O2 sensor, 30 purge valve, 31 canister, 201 purge concentration detection means, 206 purge flow rate control means, 207 injector control means, 208 automatic stop start determination means, 209 automatic stop start control means, 210 automatic stop prohibition means, Kfb A / F feedback correction coefficient (fuel control value), Ne rotation speed, Nprg purge concentration, Qprg purge flow rate, Vs vehicle speed.

Claims (3)

A canister that is provided in a fuel supply system for an engine mounted on a vehicle and adsorbs the evaporated fuel, and receives a negative pressure generated in an intake system of the engine to release the evaporated fuel as a purge gas;
A purge flow rate control means for controlling a purge flow rate of the purge gas introduced into the engine;
Purge concentration detecting means for detecting the purge concentration of the purge gas introduced into the engine;
An engine control device comprising: an automatic stop start control means for automatically stopping the engine when a predetermined automatic stop condition is satisfied, and automatically starting the engine when a predetermined automatic start condition is satisfied after the automatic stop;
An engine control device further comprising: an automatic stop prohibiting means for prohibiting an automatic stop process by the automatic stop start control means when the purge concentration shows a predetermined value or more.   2. The engine control apparatus according to claim 1, wherein the purge concentration detection means detects the purge concentration based on a fuel control value of the engine.   The engine control apparatus according to claim 1 or 2, wherein the predetermined value is set to a value that does not adversely affect exhaust gas or drivability in an operation state after restarting the engine.

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