JP2856469B2 - Engine fuel control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel control device for a fuel injection type engine.

(Prior Art) Generally, in a fuel injection engine, one of the engines is used.
A fuel amount (basic injection amount) corresponding to the intake air amount per stroke is calculated in relation to the engine speed, and this is injected from the injector to the intake system.
Such a fuel supply system is based on the premise that the entire amount of the fuel injected into the intake system is directly sucked into the combustion chamber.

However, in the fuel injection system, the fuel is not sufficiently vaporized and atomized, so that part of the fuel injected from the injector into the intake system is directly sucked into the fuel chamber, and the other part is not. Adhering to the intake passage wall and remaining,
It is vaporized and inhaled during the next injection. Therefore, a difference occurs between the amount of fuel actually sucked into the combustion chamber and the required fuel amount of the engine (that is, the basic injection amount), resulting in deterioration of the operability of the engine.

In view of such circumstances, for example, Japanese Patent Application Laid-Open No. 58-8238 discloses that the amount of combustion supplied to the engine is determined by the amount of fuel directly injected into the combustion chamber of the fuel injected from the injector and the intake passage wall. It has been proposed to perform a so-called wet correction which is set based on the amount of fuel removed from the fuel vaporized and removed into the combustion chamber.

(Problems to be Solved by the Invention) By the way, the wet correction is performed by, of the amount of fuel injected into the intake passage, the amount of fuel directly admitted to the combustion rate and the amount of fuel adhering to the wall surface of the intake passage. It is premised to predict the ratio of the amount removed and taken into the combustion chamber during the next fuel injection after being vaporized.

However, the ratio of the amount of fuel directly entering and the amount of carry-out is a fluid thing that fluctuates depending on the amount of fuel adhering to the intake passage wall (hereinafter, referred to as wet amount) as described later, and is therefore accurate. In order to realize a proper wet correction, it is necessary to sufficiently consider this wet amount.

That is, in general, the ratio of direct entry to the total intake fuel amount (direct entry ratio) and the ratio of carry-out (carry-out ratio) are set in advance based on the results of an operation test before shipment. In other words, the direct entry rate and the carry-out rate are set based on a state in which the inside of the intake passage is dry (that is, a state in which there is almost no wet amount).

However, in the normal operation state of the engine, even if there is a slight difference in the intake passage, the fuel is always attached to the intake passage. When performing the fuel control, the fuel control that is different from the actual fuel intake state is inevitably performed.

Further, even when considering the wet amount in this fuel control, it is necessary to sufficiently consider not only the presence or absence of the wet amount but also the degree of the wet amount.

That is, since the intake passage is generally formed by casting, the passage wall composed of the casting surface itself is not a smooth surface but has uneven unevenness. Therefore, when fuel is injected into the intake passage, the passage is formed. The fuel adhering to the wall enters the concave portion of the wall and is stored.
On the other hand, the evaporation of the adhered fuel is mainly governed by the quality of the contact state with the intake air flow and the level of the passage wall temperature. The state of contact with the fuel becomes extremely poor and its evaporability is impaired (that is, the carry-out rate is reduced), and the injected fuel also directly collides with the irregularities on the wall, so that the suction into the fuel chamber is prevented. As a result, an increase in the wet amount and a decrease in the direct entry are caused. On the other hand, when the wet amount is large, the contact state between the adhering fuel and the intake air flow is improved, so that the carry-out rate is increased, and the intake of the injected fuel into the combustion chamber is promoted, so that the amount directly entering the combustion chamber is increased. become.

As described above, the amount of the wet amount has a large effect on the ratio of the direct fuel input and the fuel removed, so if this is not taken into account in the fuel control, appropriate fuel control suited to the actual operating conditions can be realized. You can't get it.

However, in the above-mentioned known example, since no consideration is given to such a wet amount in the intake passage, an appropriate wet correction cannot be performed.
As a result, there is a concern that the output performance or exhaust performance of the engine may be deteriorated due to the deviation of the air-fuel ratio.

Therefore, the present invention is to provide an engine fuel control device that can always perform appropriate wet correction by taking into account the wet amount in the intake passage when predicting the amount of adhering fuel directly entering and removing it. It is.

(Means for Solving the Problems) In the present invention, as a specific means for solving such problems, a fuel supply amount supplied to a combustion chamber of an engine is directly supplied to a combustion chamber of fuel injected from an injector. In an engine in which the direct intake portion and the carry-out portion in which the fuel attached to the intake passage wall is vaporized and taken in are predicted and set, respectively, the engine speed detection means and the intake air amount detection means Means for detecting the amount of fuel supplied to the intake passage wall based on the detected amount of fuel and the detection signal from the engine temperature detecting means. And changing means for changing the predicted amount of the carry-in or the directly-entered portion such that the directly-entered portion becomes larger than the carry-out portion in accordance with the increase in the amount of the attached fuel. It is characterized by having.

(Operation) With this configuration, in the present invention, when predicting the amount of direct entry and the amount of carry-out, the amount of the directly-entered portion is changed to be larger than the amount of carry-out with an increase in the amount of attached fuel. Therefore, in view of the phenomenon that as the amount of deposited fuel increases, the wall surface of the intake passage is smoothed by the deposited fuel and the direct intake of fuel into the combustion chamber is promoted, the predicted amount of the direct entry is as much as possible the actual amount. Will be approximated.

(Effect of the Invention) Therefore, according to the fuel control device for an engine of the present invention,
Since the predicted amount of the direct injection is as close as possible to the actual amount, the deviation of the air-fuel ratio is reduced, and there is an effect that a higher level of engine performance is realized.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an intake / exhaust system of a fuel injection type automobile engine 1 provided with a fuel control device according to an embodiment of the present invention. In FIG. 1, reference numeral 2 denotes an intake passage, and 3 denotes an exhaust passage. The intake passage 2 is provided with an injector 4, a throttle valve 5, and an air flow meter 6, and the exhaust passage 3 is provided with a catalytic converter 7.
Further, the engine 1 is provided with a water temperature sensor 8 and a crank angle sensor 9.

The detection signals of these sensors are input to the control unit 10. The control unit 10 responds to the intake air amount and the wet amount remaining on the wall of the intake passage 2 based on the input signals. The fuel supply amount is calculated, and the valve opening time of the injector 4 is controlled.

In this embodiment, a so-called split injection system in which the fuel injection is divided into both the intake stroke and the combustion stroke of the engine is adopted.

Hereinafter, the control of the fuel supply amount by the control unit 10 will be described in detail. Prior to this, the basic control concept of the present invention will be briefly described with reference to FIG.

As shown in FIG. 14, the fuel injected from the injector 4 is divided into a direct input fraction F ₂ is directly drawn into the combustion chamber 1a and the attachment component F ₁ adhering to the wall surface of the intake passage 2. Further, the fuel F ₃ adhering to the wall surface of the intake passage 2 is vaporized and carried away F ₄ which is sucked into the combustion chamber 1 a, remains as it is without being vaporized, and is vaporized and sucked at the next injection. It is divided into the amount of residual fuel. Therefore, when performing the wet correction in consideration of the carry-out amount, the wet amount serving as the basis for the calculation of the carry-out amount is determined by comparing the amount of the fuel that was previously adhered to the intake passage wall with the amount of the adhered amount to the intake passage wall. It is necessary to calculate based on the remaining fuel not removed by vaporization, and in this embodiment, a calculation method based on such a concept is adopted.

Further, as described above, the wet correction is performed on the basis of the ratio of the direct entry and the removal of the fuel, that is, the direct entry rate α and the removal rate β, and the direct entry rate and the removal rate are Both are determined based on experimental data. In this case, the ratio between the direct entry rate and the carry-out rate fluctuates depending on the amount of wetness. Therefore, if this wetness was not considered at all, it would be impossible to perform proper wet correction. As described above.

Therefore, in this embodiment, the present invention is applied,
The predictions of the direct entry rate and the carry-out rate are changed (corrected) according to the wet state, so that the control can be performed more in accordance with the actual operation state.

Hereinafter, the control of the fuel supply amount of the present invention will be described in detail based on embodiments.

Main Routine In the main routine of FIG. 2, after starting the control, first, the control conditions are read and calculated (steps S1 to S1).
6).

That is, first, the output signal Q of the air flow meter and the engine speed N corresponding to the intake air amount are read (steps S1, 2).

Thereafter, based on the detected values, the filling efficiency Ceo passing through the air flow meter is calculated by the following equation (Step S).
3).

Ceo = Ka · Q / N Ka is a constant Next, the cylinder suction charging efficiency Ce this time is obtained by the following equation.

Ce = Kc · Ce + (1−Kc) · Ceo Kc is a constant (0 ≦ Kc <1) Then, based on the cylinder suction / filling efficiency Ce, the intake flow rate Qcyl at the injector mounting portion is calculated from the following equation (step S5). .

Qcyl = (1 / Ka) · Ce · N Further, in step S6, the current engine coolant temperature Tw is read. Thus, the reading of the control conditions and the like are completed.

Next, the gist of the present invention is to predict and set the direct entry rate and the carry-out rate corresponding to the operating state of the engine,
The direct entry rate and the carry-out rate are corrected according to the wet amount (steps S7 to S15).

That is, in step S7, the wet amount τm _N at the time of the previous control (set in a trailing injection processing routine described later) is read.

Next, in step S8, the injection at the intake stroke when performing the split injection of fuel, i.e., the direct input ratio alpha _T and carry-off ratio beta _T when the trailing injection, intake flow rate Qc and the cooling water temperature Tw
Indexes are respectively indexed from the map shown in FIG. 6 with y1 as a parameter. Also, injection in the combustion stroke in step S9, i.e., each index the carry-off ratio beta _L and direct input rate alpha _L at the leading injection map of FIGS. 7 and 8.

Next, in step S10, the wet weight .tau.m direct input rate corresponding to _N alpha _T, alpha correction coefficient γα of _L, as well as calculating the map of FIG. 9 that the intake air temperature and the wet weight .tau.m _N as a parameter, step In S11, the carry-out rate β _T , β
The correction coefficient γβ of _L is calculated from the map shown in FIG.

Then, the index correction coefficient Ganmaarufa, the direct input rate γβ α _T, α _L and carry-off ratio beta _T, to compensate for this by multiplying the beta _L, direct input rate value after correction, respectively alpha _T, alpha _L and carried away The ratios β _T and β _L are used for subsequent control (step S12).
~ 15).

Here, the correction coefficient Ganmaarufa of direct input rate shown in FIG. 9 is a and intake air temperature becomes higher large value, moreover γα = 1.0γ more value as wet weight .tau.m _N increases.
This is because, as the wet amount increases, the adhering fuel smoothes the wall of the intake passage and promotes the direct intake of fuel into the combustion chamber, and the higher the intake temperature, the better the vaporization of the fuel and the more the direct entry. , And the direct entry are based on the fact that they are considered to increase more than the values based on the experimental data (that is, the values when there is no wet amount) and not decrease any more.

Further, the correction coefficient γβ the carry-off ratio shown in FIG. 10, the above and wet weight .tau.m _N is large enough and the intake air temperature by substantially the same reason is the higher value greater, the correction coefficient γβ low wet In the quantity range, γβ <1.0. This is because in the wet weight .tau.m _N is small region is based on the adhesion fuel due to evaporation is inhibited contact with infiltrated air flow in the recess of the intake passage wall surface.

In this embodiment, both the direct entry rate and the carry-out rate are corrected (that is, changed) by the wet amount. However, in another embodiment of the present invention, either one of the two is used. Only the correction may be made.

Next, in step S16, the warm-up increasing rate Cw corresponding to the cooling water temperature Tw is calculated based on the map shown in FIG.
Further, in step S17, the basic injection pulse width τa is calculated based on the warm-up increasing rate Cw and the cylinder charging efficiency Ce obtained in step S4.

_{τa = K F · Cw · Ce} K F is a constant then reads the battery voltage V _B (step S1
8), respectively and calculates an invalid injection time Tauv ₂ when ineffective injection time Tauv ₁ and split injection from the map shown in FIG. 12 on the basis of this at the time of non-split injection (step S19), the division ratio Rinj split injections Calculation is performed based on the map of FIG. 13 (step S20).

Next, in step S21, the division ratio Rinj is compared with the minimum division ratio Krmn (0 <Krmn <1). If the result of the determination is that Rinj ≧ Krmn, step S2 is further executed.
In 2, it is determined whether the decomposition ratio Rinj is greater than a value obtained by subtracting the minimum division ratio Krmn from 1 or not. And the split ratio Ri
If nj is larger, the split prohibition flag Frinh is set to 0 (step S23), and the split injection invalid injection time τv ₂ is set to the practical value of the invalid injection time τv (step S23).
S24), a leading injection processing subroutine and a trailing injection processing subroutine for N cylinders are executed (steps S25 and S26).

On the other hand, if the result of the determination in step S21 is that Rinj <Krmn, the division ratio Rinj is set to 0 (that is, only the leading injection is performed), and the result of the determination in step S22 is that Rinj < If (1-Krmn), the division ratio
Set Rinj to 1 (ie, only trailing injection)
After that, the split prohibition flag Frinh is set to 1 and the non-split injection invalid injection time τv ₁ is set to the practical value of the invalid injection time τv (steps S27, S28, S29, S30).

Thereafter, a leading injection processing routine and a trailing injection processing routine for the N cylinders are executed (steps S25 and S26).

Next, the leading injection processing routine will be described with reference to the flowchart shown in FIG.

In this control, first, in step S31, it is determined whether or not a wet correction inhibition counter Cwet is 0. Then, if it is 0, the wet correction injection pulse width .tau.e _N of N cylinders is calculated by the equation of _{τe N = (τa-β L} · τm N) / α L ( step S32), also if not 0 as the wet correction injection pulse width .tau.e _N basic injection pulse width τa (step S33).

Next, in step S34, it is determined whether or not the division prohibition plug Frinh is 0. If it is 0, the leading injection pulse width τe _LN is calculated from the wet correction injection pulse width τe _N and the division ratio Rinj (step S34). Along with S35), the expected value of the trailing injection pulse width τe _TN is calculated by subtracting the leading injection pulse width τe _LN from the wet correction injection pulse width τe _N (step S36).

Then, in step S37, it is compared with the trailing injection pulse width .tau.e _TN and the pulse width limit value ktmn, .tau.e _TN ≧
In the case of Ktmn, this is followed by τe _TN <Ktm
a pulse width limit value Ktmn in case of n is set to the trailing injection pulse width .tau.e _TN (step S46) and the trailing injection pulse width .tau.e _TN wet correction injection pulse width .tau.e
_After subtracting the value from _N and newly setting the value as the leading injection pulse width τe _LN (step S47), the process moves to the comparison between the leading injection pulse width τe _LN and the pulse width lower limit Ktmn (step S38).

If it is determined in step S38 that τe _LN ≧ Ktmn, subsequently, if τe _LN <Ktmn, the pulse width lower limit value Ktmn is set to the leading injection pulse width τe _LN (step S48). Then, the leading injection pulse width τe _LN is subtracted from the wet correction injection pulse width τe _N and the value is newly set as the trailing injection pulse width τe _TN (step S49). (Step S50).

On the other hand, if the result of the determination in step S34 is that Frinh ≠ 0, it is determined in step S39 whether or not the division ratio Rinj is 0 (that is, whether or not only the leading injection is performed). As a result of the determination, if Rinj = 0, only the leading injection is performed. In this case, the wet correction injection pulse width τe _N itself is replaced with the leading injection pulse width τe.
_LN is set (step S40), and the trailing injection pulse width τe _{TN is set} to 0 (step 41).

Then, in step S44, the leading injection pulse width τe _LN is compared with the pulse width lower limit value Ktmn, and τe
_{If LN} ≥Ktmn, this is followed by τe _LN
If <Ktmn, the pulse width lower limit value Ktmn is set to the leading injection pulse width τe _LN (step S45), and then the flow proceeds to the calculation of the injector pause time τrst (step S50).

After the calculation of the pause time τrst in step S50 is completed, the pause time τrst is compared with the pause time lower limit value Krst in step S51. If τrst ≧ Krst, the trailing injection prohibition flag Ftinh _N Is set to 0 (step S52), and if τrst <Krst, the wet correction pulse width τe _N itself is replaced with the leading injection pulse width τe.
_LN and trailing injection prohibition flag Ftinh _N
Is set to 1 (steps S53 and S54).

Next, resets the timer Tinj _N in step S55, the injection end time by adding the leading injection pulse width .tau.e _LN and invalid injection time τv in step S56, i.e., set this by calculating the pulse width Tend _N ,
Thereafter, the fuel injection is executed with the injection start flag Finj _{N set} to 1 (steps S57 and S58). = On the other hand, if Rinj ≠ 0 as a result of the determination in step S39, the leading injection pulse width τe _{LN is set} to 0, and the wet correction injection pulse width τe _N itself is set to be trailing injection only. The trailing injection pulse width τe _TN is set (steps S42 and S43).

Next, in step S59, the addition to calculating the effective division ratio Rinj _N following equation Rinj _N = 1-a (τe _LN / τe _N), the basic injection pulse width in τa on the basis of the effective division ratio Rinj _N in step S60 calculating a leading injection amount .tau.a _LN by the following equation _{τa LN = (1-Rinj N} ) · τa.

Further, in step S61, calculates the fuel distribution .tau.c _LN supplied to the cylinder only by the leading injection by the following equation _{τc LN = α L · τe LN} + β L · τm N, intake manifold attached amount of the leading injection in the last step S62 τm _LN is calculated by the following equation: τm _LN = (1−α specific absorption _L ) · τe _LN + (1-Rinj _N ) · (1−β _L ) · τm _N , and the control is completed.

Next, the trailing injection processing routine will be described with reference to the flowchart shown in FIG.

After start of control, first, the basic injection pulse width .tau.a in step S63, is compared with the fuel distribution .tau.c _LN when fuel supply is performed only at the leading injection in the case of .tau.a ≧ .tau.c _LN further in step S64 It is determined whether or not the wet correction inhibition counter Cwet is 0.

Then, if it is Cwet = 0 is tracing injection prohibition flag Ftinh _N, it is determined whether 0 in step S65, Ftinh in the case of _N = 0 is further wet correction injection pulse width of N cylinders in step S66 following equation _{τe N τe N = (τa-} β T · τm N) / α is calculated by _T, also following equation trailing injection pulse width .tau.e _TN during split injection at step _{67S τe TN = (τa-τa} LN It is calculated by _{-Rinj N · β T · τm N} ) / α T.

Next, in step S70, it is determined whether or not the division prohibition flag Frinh is 0. If Frinh = 0, the trailing injection pulse width τe _TN is compared with the pulse width lower limit value Ktmn in step S71. Τe _TN ≧ Kt
If it is mn, in step S80, the idle time τrst of the injector is calculated by the following equation: τrst = (60 / N) − (τe _TN + τv).

Then, in step S81, the pause time τrst is compared with the pause time lower limit value Ktrst. If τrst <Ktrst, the trailing injection pulse width τe _TN is calculated in step S82 by the following equation: τe _TN = (60 / N) Calculate by-(Ktrst + τv).

Thereafter, the timer is reset Tinj _N in step S83, the injection end time at step S84 that is, the pulse width T
end _N is obtained by adding the trailing injection pulse width τe _TN and the invalid injection time τv, and this is set.

Next, in step S86, the injection start flag Ftinh _N
Is set to 1 and injection is executed in step S87. Finally, to calculate the total wet weight .tau.m _N by the following equation _{τm = (1-α T)} · τe TN + Rinj N · (1-β T) · τm N + τm LN at step S89. The so direct input ratio as described above on the basis of the wet weight .tau.m _N and carry-off ratio of the correction.

On the other hand, if it is determined that .tau.a <.tau.c _LN in the step S63 performs an operation of the intake manifold adhesion amount .tau.m _N goes to step S89.

If it is determined in step S64 that “Cwet ≠ 0” (that is, if wet correction is not performed), the process proceeds to step S64.
In S72, the basic injection pulse width τa and wet correction pulse width .tau.e _N. Then, in step S73, it is determined whether the trailing injection inhibition flag Ftinh _N is 0. If Ftinh _N = 0, the value obtained by subtracting the leading burden τa _LN from the basic injection pulse width τa in step 74 is determined. After the trailing injection pulse width τe _TN , the process proceeds to step S70 to execute the following control.

Further, when it is determined in step S65 that Ftinh _N ≠ 0 (that is, when trailing injection is prohibited).
The calculates the wet correction injection pulse width .tau.e _N in step S68, further leading injection pulse width The wet correction injection pulse width .tau.e _N in step S69 tau
e _LN and the trailing injection pulse width τ e _{TN is set} to 0. Thereafter, in step S85, the leading injection pulse width τe _LN and the invalid injection time τv are added to calculate the final injection time, that is, the pulse width Tend _N (that is, the pulse width is extended), and in step S88, the leading injection pulse is extended. The time is extended, and thereafter, the flow shifts to step S89.

If it is determined in step S70 that Ftinh _N ≠ 0 (that is, if the split injection is not performed), then in step S75, the split ratio Rinj is 1 (that is, whether the trailing injection only or the leading injection only). If Rinj = 0, in step S76, the wet correction injection pulse width τe _N and the pulse width lower limit value Ktmn are determined.
And if τe _N = Ktmn, step S78
In the above, the wet correction injection pulse width τe _{N is set} to the trailing injection pulse width τe _TN, and when τe _N ≠ 0, the pulse width lower limit value Ktmn is set to the trailing injection pulse width τe _{TN in} step S77, and the process proceeds to step S80. Transition.

Further, when it is determined in step S71 that τe _TN <Ktmn, the process proceeds to step S77.

 Thus, the trailing injection processing routine ends.

[Brief description of the drawings]

FIG. 1 is a system diagram of an engine provided with a fuel control device according to an embodiment of the present invention, FIGS. 2 to 4 are control flowcharts in the fuel control device, and FIG. , FIG. 6 is a carry-out rate map during the suction stroke injection, FIG. 7 is a straight-in rate map during the combustion stroke, FIG. 8 is a carry-out rate map during the combustion stroke, FIG. 9 and FIG. , A correction value map based on the above, FIG. 11 is a warm-up increase rate map, FIG. 12 is an invalid injection time map, FIG. 13 is an injection split ratio map, and FIG. FIG. DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Intake passage 3 ... Exhaust passage 4 ... Injector 5 ... Throttle valve 6 ... Air flow meter 7 ... Catalyst converter 8 ... Water temperature sensor 9 ... Control unit

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideki Kobayashi 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References JP-A-58-8238 (JP, A) JP-A-1 -216042 (JP, A) JP-A-3-210035 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 41/04 330 F02D 45/00 364 F02D 45/00 312

Claims (1)

(57) [Claims] 1. A fuel supply amount supplied to a combustion chamber of an engine is obtained by evaporating fuel directly injected into a fuel chamber from fuel injected from an injector and fuel adhering to an intake passage wall. The amount of fuel supply is determined based on the detection signals from the engine speed detection means and the intake air amount detection means, and the fuel supply amount and An adhering fuel amount detecting means for detecting an adhering fuel amount adhering to the intake passage wall based on a calculation based on a detection signal from the engine temperature detecting means; and Changing means for changing the amount of direct entry to be greater than the amount of carry-out as the amount increases.