JPH0586934A - Transient fuel quantity corrector for engine - Google Patents

Abstract

PURPOSE:To improve responsiveness for change in the amount of fuel injection, in relation to the change in the amount of intake air at the time of acceleration, by calculating changing velocity as well as changing acceleration of a throttle valve opening, and by incrementally correcting the amount of reference injection when both of the calculated changing velocity and the changing acceleration are of positive values. CONSTITUTION:A throttle sensor 30 for calculating the amount of reference injection is calculated based on the amount of intake air, and for detecting the opening of a throttle valve 15, is provided. A throttle valve opening change calculation means 30 for calculating the changing velocity as well as the changing acceleration of the opening of the throttle valve, is also provided. When both of the changing velocity and of the changing acceleration are of positive values, the amount of the reference injection is increased and is thus corrected, and when they are of negative values, the amount of reference injection is reduced and is thus corrected, by a reference injection amount correction means 10. The changing amount of fuel injection in relation to the change in the amount of intake air can be followed with no delay in responsiveness while excessive correction in the amount of fuel infection can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine transient fuel amount correction device for preventing a response delay of a fuel injection amount change during acceleration / deceleration.

[0002]

2. Description of the Related Art Generally, in a fuel injection engine,
Basically, a fuel injection amount that realizes a predetermined air-fuel ratio is calculated based on the intake air amount, and fuel injection is performed according to this calculated value. Here, as the intake air amount detecting means, conventionally, a linear sensor (L-J) arranged in the upstream portion of the intake passage is widely used, but in recent years, the intake air amount is calculated from the intake boost pressure downstream of the throttle valve. Intake air amount detecting means (D
-J) is proposed. The DJ is usually arranged near the engine body.

By the way, generally, the detection of the intake air amount by the intake air amount detecting means is accompanied by a slight response delay. Therefore, the detection of the increase in the intake air amount at the time of acceleration is actually detected at the detection position. It will be later than the increase in intake air amount. Further, even during deceleration, the detection of the decrease in the intake air amount is delayed from the actual decrease in the intake air amount at the detection position. During such acceleration / deceleration, the change in the fuel injection amount occurs due to the detection of the change in the intake air amount. Therefore, the change in the fuel injection amount also has a response delay with respect to the actual change in the intake air amount at the intake air amount detection position. It will be.

However, the intake air amount detecting means is L-
In the case of J, L-J is arranged in the upstream part of the intake passage, and L-J
Since the intake passage length from J to the combustion chamber is relatively long, L
There is a slight delay until the actual change in the intake air amount at the -J position is reflected in the combustion chamber. Here, during acceleration / deceleration, the response delay of the fuel injection amount change is
Since the time delay due to the intake passage length is almost equal, there is not much time difference between the intake air amount change and the fuel injection amount change in the combustion chamber.

On the other hand, the intake air amount detecting means D-
In the case of J, since DJ is arranged near the engine body, the change in intake air amount at the DJ arrangement position is reflected in the combustion chamber with almost no time delay. For this reason, in the combustion chamber, the change in the fuel injection amount lags behind the change in the intake air amount in the initial stage of acceleration / deceleration, the air-fuel ratio becomes over lean during acceleration, resulting in a decrease in acceleration. There is a problem that it becomes rich and causes misfire or outer burn.

Therefore, the change in the intake air amount is the change in the opening of the throttle valve (the change in the position of the throttle valve in the rotating direction).
Focusing on that caused by, the fuel injection control method has been proposed in which the fuel injection amount is increased according to the changing speed of the throttle valve opening during acceleration (for example,
(See JP-A-58-150045).

[0007]

However, in the initial stage of acceleration, the rate of change of the throttle valve opening increases with time, and it takes some time for the rate of change to stabilize, during which time the appropriate amount of fuel injection is increased. Can't do. Therefore, even in the above-described conventional fuel injection control method in which the fuel injection amount is increased according to the changing speed of the throttle valve opening, there is still a problem that the response delay is accompanied by the change in the fuel injection amount. Further, there is a similar problem during deceleration. Further, in such a conventional control method, since the time for which the throttle valve opening changes is considerably longer than the response delay time of the intake air amount detecting means, the intake air amount detection value and the actual intake air amount to the engine are The fuel injection amount is corrected even when
(Excessive correction) is performed, and during this time, the air-fuel ratio is disturbed and the combustibility deteriorates. The present invention is
In order to solve the above-mentioned conventional problems, in a fuel injection engine provided with an intake air amount detecting means for detecting an intake air amount from an intake boost, intake air in a combustion chamber during acceleration / deceleration To provide a transient fuel amount correction device for an engine that can follow a change in the fuel injection amount with respect to a change in the air amount without a response delay and prevent excessive correction of the fuel injection amount. To aim.

[0008]

In order to achieve the above object, the first aspect of the present invention relates to a basic injection amount calculating means for calculating a basic injection amount of a fuel injection valve based on an intake air amount, and a throttle valve opening degree. In a fuel injection type engine provided with a throttle valve opening detecting means for detecting, a throttle valve opening change calculating means for calculating a changing speed and a changing acceleration of the throttle valve opening, and the throttle valve opening change calculating means. When the change speed and the change acceleration of the throttle valve opening calculated by are both positive values, a basic injection amount correction unit for increasing and correcting the basic injection amount calculated by the basic injection amount calculation unit is provided. A transient fuel quantity correction device for an engine is provided.

A second aspect of the invention is a basic injection amount calculating means for calculating the basic injection amount of the fuel injection valve based on the intake air amount,
In a fuel injection engine provided with a throttle valve opening detection means for detecting a throttle valve opening, a throttle valve opening change calculation means for calculating a change speed and a change acceleration of the throttle valve opening, and the throttle valve When the change speed and the change acceleration of the throttle valve opening calculated by the opening change calculating means are both negative values, the basic injection amount correcting means for reducing the basic injection amount calculated by the basic injection amount calculating means. (EN) A transient fuel quantity correction device for an engine, characterized by being provided with.

In a third aspect of the present invention, in the engine transient fuel amount correction device according to the first or second aspect, the basic injection amount correction means further includes a basic fuel injection amount based on the change amount of the intake air amount. There is provided a fuel quantity correction device for an engine transient, which is characterized in that

[0011]

EXAMPLES Examples of the present invention will be specifically described below.
As shown in FIG. 1, when the intake valve 1 is opened, the fuel injection engine CE sucks the air-fuel mixture from the intake port 2 into the combustion chamber 3, compresses the air-fuel mixture with the piston 4, and ignites it. When the plug 5 is ignited and burned and then the exhaust valve 6 is opened, the combustion gas is discharged from the exhaust port 7. Here, the intake valve 1 and the exhaust valve 6 are configured to be opened and closed by the cam mechanism 8 at a predetermined timing synchronized with the engine rotation. Further, a high voltage is applied to the spark plug 5 by the ignition device 9 at a predetermined timing synchronized with the engine rotation, and the air-fuel mixture is ignited by sparks generated by the high voltage.

In order to supply air to the engine CE, an intake passage 12 which communicates with the intake port 2 is provided, and in this intake passage 12, suspended dust in the intake air is sequentially provided from the upstream side in the intake air flow direction. Air cleaner 13 to remove
A throttle valve 15 that opens and closes in conjunction with an accelerator pedal (not shown), a surge tank 16 that stabilizes the flow of intake air, an intake boost sensor 21 that detects the intake air amount from the intake boost, and an intake A fuel injection valve 17 for injecting fuel into the air is provided. A bypass intake passage 18 that bypasses the throttle valve 15 is provided in the intake passage 12, and the bypass intake passage 18 has an I
An idle speed control device 20 having an SC valve 19 is provided.

An exhaust passage 22 communicating with the exhaust port 7 is provided for discharging exhaust gas, and an exhaust gas purifying device 23 using a three-way catalyst is provided in the exhaust passage 22. Then, in order to reduce the NOx generation amount,
An EGR passage 24 that recirculates a part of the exhaust gas to the intake passage 12 is provided, and the EGR passage 24 has an EGR valve 25 that adjusts the EGR amount.
Is provided.

A control unit 10 is provided to control the engine CE. The control unit 10 has an intake boost (intake air amount) detected by an intake boost sensor 21 and a throttle detected by a throttle sensor 30. The valve opening, the engine water temperature detected by the water temperature sensor 31, the O ₂ concentration (air-fuel ratio) in the exhaust gas detected by the O ₂ sensor 32, the atmospheric pressure detected by the atmospheric pressure sensor 33, and the rotation speed sensor 34. The detected engine speed and the like are input as control information. And
The control unit 10 is configured to perform various predetermined engine controls based on these control information. In the following, only the fuel injection amount correction control during acceleration / deceleration, which is the gist of the present application, will be described. Other engine controls, such as idle rotation control and EGR control, are performed by a commonly used ordinary control method, and therefore description thereof will be omitted.

The control method of the fuel injection amount correction control will be described below with reference to the flow chart shown in FIG. When the control is started, first in step # 1, the throttle valve opening TV detected by the throttle sensor 30 is detected.
O and the intake boost Po (intake air amount) detected by the intake boost sensor 21 are read.

Next, in step # 2, the differential value DTVO of the throttle valve opening TVO with respect to time, that is, the changing speed of the throttle valve opening is calculated, and this DT is calculated.
It is compared and judged whether VO is a positive value. If it is determined that DTVO> 0 (YES), the differential value DDTVO with respect to the time of the change speed DTVO, that is, the change acceleration of the throttle valve opening is calculated in step # 3, and this DDTVO is a positive value. Is compared or determined. On the other hand, in step # 2, DTVO <
If it is determined to be 0 (NO), then step # 4
Then, DDTVO is calculated and it is compared / determined whether or not this DDTVO is a negative value. Although not shown in detail, when DTVO = 0, step # 6 described later is executed.

In this embodiment, DTVO is used during acceleration.
> 0 and DDTVO> 0, the basic fuel injection amount is increased and corrected in accordance with DDTVO, and at the time of deceleration, when DTVO <0 and DDTVO <0, the basic fuel injection amount is DDTVO. According to the above, the weight reduction is corrected. As shown in FIG. 3, during acceleration, for example, when the throttle valve opening changes from d ₁ to d ₂ , the throttle valve opening change exhibits the following characteristics. In FIG. 3, H ₁ is a case where the acceleration request is strong and the throttle valve 15 is suddenly opened.
₂ and H ₃ are the cases where the acceleration request becomes weaker. (1) In the process in which the throttle valve 15 is opened from d ₁ to d ₂ , the change acceleration DDTVO initially has a substantially constant positive value corresponding to the acceleration request. At this time, the changing speed DTVO rapidly increases. (2) In the middle period, the change acceleration DDTVO becomes almost zero. At this time, the changing speed DTVO is slightly decreased, but becomes a substantially constant value. (3) At the end of the period, the change acceleration DDTVO becomes a negative value. At this time, the change speed DTVO sharply drops.

Here, the response delay of the change of the fuel injection amount with respect to the change of the intake air amount becomes remarkable because the change speed DTVO.
Is at the stage of (1) in which the fuel cell suddenly rises, and after the stage of (2), the change in the fuel injection amount almost follows the change in the intake air amount. Then, in this embodiment, the fuel injection amount is increased only in the state (1), that is, when DDTVO> 0 and DTVO> 0. Therefore, the response to the change in the fuel injection amount at the time of acceleration becomes very fast, and the increase is stopped at the time (2) when it becomes unnecessary to increase the amount, and the excessive increase is not performed. Therefore, the air-fuel ratio is maintained at an appropriate value during acceleration, and the combustibility is enhanced. On the other hand, in the conventional fuel injection control method in which the fuel injection amount is increased according to the changing speed of the throttle valve opening, the fuel injection amount is not appropriately increased at the stage of (1), and ( Since the fuel amount is increased in the stage of 2), the change in the fuel injection amount cannot quickly respond to the acceleration, and the fuel injection amount is excessively increased until an unnecessary time.

As shown in FIG. 4, at the time of deceleration when the throttle valve opening is closed from d ₃ to d ₄ , the change acceleration DDTVO and the change speed DTVO are almost the same as each other, although the positive and negative are opposite to those at the time of acceleration. Therefore, according to the present embodiment, the fuel injection amount change response to deceleration becomes very fast similarly to the acceleration, and the fuel consumption is stopped at the time when it becomes unnecessary to reduce the fuel injection amount. Therefore, the air-fuel ratio is maintained at an appropriate value during deceleration, and the combustibility is enhanced. In FIG. 4, the deceleration request becomes weaker in the order of H ₄ , H ₅ , and H ₆ .

Specifically, in step # 2, DTVO> 0.
Is determined (YES), and the DDT is performed in step # 3.
When it is determined that VO> 0 (YES), in step # 5, the change acceleration DDTV with respect to the basic fuel injection amount.
The positive acceleration correction value CATU corresponding to O is calculated using a predetermined functional relationship (CATU = f (DDTVO)). The function f (DDTVO) is set to have such a characteristic that CATU increases linearly in a positive region with respect to an increase in DDTVO, for example.

If it is determined in step # 2 that DTVO <0 (NO), and if it is determined in step # 4 that DDTVO <0 (YES), then in step # 7, for the basic fuel injection amount, The negative acceleration correction value CATU corresponding to the change acceleration DDTVO has a predetermined functional relationship (CATU = f
(DDTVO)). Note that the function f (DD
TVO) is, for example,
Is set so that it decreases linearly in the negative region.

If neither DTVO> 0 and DDTVO> 0 nor DTVO <0 and DDTVO <0, it is not necessary to increase or decrease the fuel, so the acceleration correction value CATU is set to 0 in step # 6. It

After the acceleration correction value CATU is calculated in this way, in step # 8, the smoothed value Pcca (i) of the intake boost Po (intake air amount) is calculated by the following equation 1. Pcca (i) = (1- K 1) · Po (i) + K 1 · Pcca (i-1) ............... formula 1 wherein, K ₁ is a predetermined averaging coefficient. Next, in step # 9, the intake boost Po (i) of this time is calculated by the following equation 2.
The intake air amount change correction value CP (i) for the basic fuel injection amount is calculated on the basis of the deviation of the above from the smoothed value Pcca (i), that is, the change amount of the intake air amount. CP (i) = K ₂ [Po (i) −Pcca (i)] …………………………………………………………………………………………………………………………………………………………………………………………………………………… 2 2 2 2 2 In addition to the acceleration correction based on the change acceleration DDTVO, the intake air amount change correction based on the change of the intake air amount is constantly performed to further improve the accuracy of the air-fuel ratio control. Intake air amount change correction value CP
(i) is a correction value for performing such correction. Here, this intake boost Po (i) and the previous intake boost P
The amount of change in the intake air amount is not calculated from the difference of o (i-1), and Po (i)
The amount of change is calculated from the difference between the smoothed value Pcca (i) and
This is to eliminate the influence of measurement error.

Subsequently, in step # 10, the injection pulse width T ₁ of the fuel injection valve 17 is calculated by the following equation 3, and this T ₁
Fuel injection is performed in accordance with. T ₁ = τe ′ [1 + CATU + CP (i) + C] Equation 3 In Equation 3, τe ′ is a well-known method based on the intake air amount, engine speed, etc. It is the basic injection pulse width (basic injection amount) calculated by. Further, C is a correction value for the temperature of intake air and the like. After that, the process returns to step # 1 and the control is continued. As described above, according to the present invention,
During acceleration / deceleration, the acceleration / deceleration of the fuel injection amount can be quickly corrected to follow the changes in the intake air amount in the combustion chamber without a response delay, and excessive acceleration / deceleration correction can be performed. Therefore, the air-fuel ratio is maintained at an appropriate value. Further, since the fuel injection amount is constantly corrected based on the change in the intake air amount, the air-fuel ratio control accuracy can be further improved.

[0025]

According to the first aspect of the invention, the fuel injection amount is increased based on the throttle valve opening change acceleration at the time of acceleration, but the change acceleration responds quickly to the acceleration operation at the start of acceleration. Therefore, the responsiveness of the fuel injection amount change to the intake air amount change at the time of acceleration is enhanced. Further, during acceleration, when the change acceleration becomes 0 or less, the increase is stopped, so that the excessive increase in fuel injection is not performed. Therefore, the air-fuel ratio can be maintained at an appropriate value during acceleration, and the combustibility can be improved.

According to the second aspect of the invention, the fuel injection amount is reduced based on the throttle valve opening change acceleration during deceleration. However, the above-mentioned change acceleration responds quickly to the deceleration operation at the start of acceleration. At the same time, the responsiveness of the fuel injection amount change to the intake air amount change is enhanced. Further, during deceleration, when the above-mentioned change acceleration becomes 0 or more, the above-mentioned amount reduction is stopped, so that the excessive amount of fuel injection is not reduced. Therefore, the air-fuel ratio can be maintained at an appropriate value during deceleration, and the combustibility is improved.

According to the third invention, basically, the same action and effect as those of the first or second invention can be obtained. Further, since the fuel injection amount is corrected based on the change in the intake air amount, the air-fuel ratio control accuracy is further enhanced.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an engine including a transient fuel amount correction device (control unit) according to the present invention.

FIG. 2 is a flowchart showing a control method of fuel injection amount correction control by a control unit.

FIG. 3 is a diagram showing characteristics of a throttle valve opening and its changing speed and changing acceleration with respect to time during acceleration.

FIG. 4 is a diagram showing characteristics of a throttle valve opening and its changing speed and changing acceleration with respect to time during deceleration.

[Explanation of symbols]

 CE ... Engine 10 ... Control Unit 15 ... Throttle Valve 17 ... Fuel Injection Valve 21 ... Intake Boost Sensor 30 ... Throttle Sensor

Claims (3)

[Claims] 1. A fuel injection type fuel injection system comprising: a basic injection amount calculating means for calculating a basic injection amount of a fuel injection valve based on an intake air amount; and a throttle valve opening detecting means for detecting a throttle valve opening. In the engine, the throttle valve opening change calculation means for calculating the change speed and the change acceleration of the throttle valve opening and the change speed and the change acceleration of the throttle valve opening calculated by the throttle valve opening change calculation means are both positive. And a basic injection amount correction means for increasing and correcting the basic injection amount calculated by the basic injection amount calculation means. 2. A fuel injection type fuel injection system comprising: a basic injection amount calculating means for calculating a basic injection amount of a fuel injection valve based on an intake air amount; and a throttle valve opening detecting means for detecting a throttle valve opening. In the engine, the throttle valve opening change calculation means for calculating the change speed and the change acceleration of the throttle valve opening, and the change speed and the change acceleration of the throttle valve opening calculated by the throttle valve opening change calculation means are both negative. And a basic injection amount correction means for reducing and correcting the basic injection amount calculated by the basic injection amount calculation means. 3. The transient fuel amount correction device for an engine according to claim 1 or 2, wherein the basic injection amount correction means further corrects the basic fuel injection amount based on the change amount of the intake air amount. An engine transient fuel amount correction device characterized by being adapted to.