JPH0454057B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronic fuel injection engine, and more particularly to a fuel control device for an engine in which a plurality of intake passages are provided for one combustion chamber.

(Prior art) For example, according to Japanese Patent Application Laid-Open No. 57-93626, 1
An engine is shown in which a first intake passage and a second intake passage are each independently opened to two combustion chambers, and the second intake passage is provided with a shutter valve. This means that at low speeds or low loads,
By closing the shutter valve and supplying intake air to the combustion chamber only from the first intake passage, the flow velocity of the intake air is increased to improve the mixability with fuel and the ignition performance,
Also, at high speeds or high loads, a large amount of intake air can be supplied through both the first and second intake passages. In such an engine, as shown in the above publication, fuel is usually supplied by a fuel injection valve installed in the first intake passage.
In some cases, fuel injection valves are installed in both of the second intake passages.

By the way, when fuel is supplied by a fuel injection valve like the above-mentioned engine, the operating state can be adjusted by applying a pulse signal with a pulse width corresponding to the engine rotation speed and intake negative pressure to the fuel injection valve. The fuel injection amount is controlled to increase or decrease accordingly. However, with such control, the fuel injection amount is increased only by an amount corresponding to the increase in the intake negative pressure during acceleration, resulting in a fuel shortage and the problem that the required acceleration performance cannot be obtained. To solve this problem, for example, as disclosed in Japanese Patent Publication No. 49-47931, during acceleration, in addition to the basic pulse with a pulse width corresponding to the rotation speed, intake negative pressure, etc., temporary pulses are injected into the fuel. Attempts have been made to improve acceleration performance by applying an increased amount of fuel to a valve to inject more fuel than the amount corresponding to the increase in intake negative pressure.

However, for one combustion chamber as described above, a first intake passage which is always open and a second intake passage which is shut off at low load by a shutter valve are provided independently, and both intake passages are supplied with fuel. In the case of engines equipped with injection valves, the problem of how to control the increase in the amount of fuel injection during acceleration as described above in terms of combustibility, etc., has not yet been resolved. Ta.

(Object of the Invention) The present invention solves the above-mentioned problems in fuel-injected engines, and includes a first intake passage that is always open to one combustion chamber and a shutter valve that is closed off at low loads. In an engine having a second intake passage and each intake passage having a fuel injection valve, in view of the fact that the characteristics of the injection amount with respect to the applied pulse width of the fuel injection valve are unstable in the low injection amount region, The fuel is injected in an increased amount during acceleration and is centrally injected and supplied by a specific injection valve. This allows for precise control of increased fuel injection during acceleration, prevents disturbances in the air-fuel ratio, and achieves good combustion conditions, while ensuring that the increased amount of fuel during acceleration is supplied to the combustion chamber without delay. The purpose is to obtain good acceleration performance.

(Configuration of the Invention) A fuel control device for an electronic fuel injection engine according to the present invention is configured as follows in order to achieve the above object.

That is, as shown in FIG. 1, there is a first intake passage _B1 that is always open to one combustion chamber A, and a second intake passage that is shut off by a shutter valve C at low loads.
In addition to providing an intake passage B ₂ , each intake passage B ₁ ,
In an engine _B2 equipped with fuel injection valves _D1 and _D2 , acceleration detection means E detects the acceleration of the engine by, for example, the opening speed of a throttle valve.
and a fuel injection valve D installed in the first intake passage _B1 which is always open without the shutter valve C among the fuel injection valves _D1 and _D2 when the detection means E detects acceleration. ₁ is provided with an increasing pulse applying means F for applying an increasing pulse of the injection amount. During acceleration, this increase pulse applying means F outputs a temporary pulse for acceleration increase, in addition to the basic pulse having a pulse width corresponding to the engine speed, intake negative pressure, etc. As a result, the fuel injection amount is increased during acceleration, and the desired acceleration performance is obtained. However, since this increased amount injection is performed for one of the two fuel injection valves D ₁ and D ₂ , that injection valve is injected with increased amount. A relatively large amount of fuel is injected during injection. Therefore, the injection amount accurately corresponds to the pulse width of the applied increase pulse.

In this case, since the increased amount of fuel is injected by the fuel injection valve D ₁ installed in the first intake passage B ₁ which is always open, the shutter valve C installed in the second intake passage B ₂ is activated during acceleration. Even if a response delay occurs in the opening operation, the increased amount of fuel injected will be reliably supplied to the combustion chamber A without delay, regardless of this delay.

(Example) The present invention will be described below based on an example shown in the drawings.

As shown in FIG. 2, the engine 1 has a plurality of combustion chambers 2...2, and each combustion chamber 2 has first and second intake ports 3 ₁ , 3 ₂ and first and second exhaust ports 4 . ₁ , 4 ₂ are provided, and each port 3 ₁ ,
First and second intake valves 5 1 _and 5 ₂ and first and second exhaust valves 6 1 and 6 ₁ are provided at the openings of 3 ₂ , 4 ₁ and 4 ₂ to the combustion chamber 2, respectively.
6 ₂ are provided. Further, an intake pipe 7 is provided on one side of the engine 1, and the intake pipe 7 has the same number of branches as the surge tank part 8 and the combustion chambers 2 branched from the surge tank part 8. Part 9...
... 9, and each branch part 9 has the first and second intake ports 3 ₁ provided in each combustion chamber 2,
3 ₂ are provided with first and second branch paths 9 ₁ and 9 ₂ that communicate with each other, respectively. As a result, first and second intake passages 10 ₁ and 10 ₂ are formed between the surge tank portion 8 and each combustion chamber 2, respectively.

Further, a shutter valve 11 is provided on each second intake passage 10 ₂ to close the second intake passage 10 ₂ when the load is low, and a shutter valve 11 is provided on each first intake passage 10 ₁ and each First and second fuel injection valves 12 ₁ and 12 ₂ are installed downstream of the shutter valve 11 on the second intake passage 10 ₂ , respectively. And these fuel injection valves 12 ₁ ,
12 ₂ from the control unit 13 the first,
Second pulse signals S ₁ and S ₂ are applied, respectively, and when the second pulse signals S 1 and S 2 are applied, the injection valves 12 ₁ and 12 ₂ inject fuel into the intake passages 10 ₁ and 1 in an amount corresponding to the pulse width of the applied pulses.
0 ₂ respectively. In that case, the control unit 13 receives a signal _S3 from the intake negative pressure sensor 14 installed in the surge tank section 8 of the intake pipe 7, and the surge tank section 8 of the intake pipe 7.
A signal from a throttle opening sensor 16 that detects the opening of a throttle valve 15 provided at an upstream position of
_S4 , a signal _S5 from the crank angle sensor 17 that detects the crank angle of engine 1, and
Idle switch 18 detects the idle state of
The output timing and pulse width of the pulse signals S _{1 and} S ₂ are determined based on these signals S ₃ to _{S 6} .

Note that exhaust gas discharged from the first and second exhaust ports 4 ₁ and 4 ₂ provided in each combustion chamber 2 is provided on the side opposite to the side where the intake pipe 7 of the engine 1 is provided. An exhaust pipe 19 is provided for merging the two.

Next, the operation of the above embodiment will be explained.

It is composed of a control unit 13 and a microcomputer, and executes a background routine shown in FIG. 3 and an interrupt routine shown in FIG. 4.

In the interrupt routine shown in FIG. 4, the engine 1 is activated at a predetermined crank angle (for example, 60 degrees before the top dead center of a specific cylinder) in response to a signal _S5 from the crank angle sensor 17.
When this happens, execution starts, and first, the engine speed is calculated in steps P ₁ and P ₂ based on the crank angle signal S ₅ , and at the same time, in step P 3, the engine speed is calculated based on the signal S ₃ from the intake negative pressure sensor ₁₄ . to detect intake negative pressure. Next, in step _P4 , the first basic map corresponding to the engine speed and intake negative pressure at that time is selected from two maps in which pulse widths corresponding to the engine speed and intake negative pressure are set in advance as shown in FIG. pulse
The pulse widths of _x1 and second basic pulse _x2 are read respectively, and the injection timing is waited for in step _P5 . Then, when a predetermined injection timing (for example, top dead center of a specific cylinder) comes, step _P6 is executed, and the first and second basic pulses x ₁ and x ₂ of the above pulse width are converted into pulse signals S ₁ and S ₂ as the first and second fuel injection valves 12 ₁ , 1
2.Apply to ₂ respectively. As a result, fuel is injected into the intake passages 10 ₁ , 10 ₂ from each fuel injection valve 12 ₁ , 12 ₂ in an amount corresponding to the rotational speed of the engine 1 and the intake negative pressure. In that case, as shown in Figure 6a and b, if the load is below a certain level and the second
When the shutter valve 11 in the intake passage ₁₀₂ is closed, the pulse width is set to zero in the region where the intake negative pressure is below a certain level in the second basic pulse map in FIG. 5b.
As shown in FIG. 6d, no fuel is injected from the second fuel injection valve ₁₂₂ .

However, the above-mentioned interrupt routine shown in FIG. 4 is executed by temporarily stopping the background routine shown in FIG. 3 when a predetermined time comes during the execution of the background routine, and then the execution ends. The background routine will then resume again. Next, this background routine will be explained.

First, this routine initializes the temporary pulse flag T and time counter value t in steps Q ₁ and Q ₂ , and then sets the throttle opening indicated by the signal S ₄ from the throttle opening sensor 16 in step Q ₃ . A-D convert the value. Next, during normal driving other than when starting, steps Q ₄ to Q ₆ and Q ₇ are executed, and 1 is added to the time counter value t, and the added counter value t is used as a parameter in step Q ₃ . The A-D converted throttle opening value θ(t) is stored. By repeating this routine a predetermined number of times, t>α(α:
(an integer greater than or equal to 1), execute steps _Q8 and _Q9 , and calculate the throttle opening value θ at that time.
(t) and the throttle opening value θ(t-α) α times before, the average rate of change in the throttle opening θ・={θ(t)−
θ(t-α)}/α is calculated, and when this is greater than the set value β, the temporary pulse flag T is set to 1 in step _Q10 . When this flag T is set to 1, steps _Q11 and _Q12 are executed, and as shown in FIG. 6e, an extraordinary pulse x1' is sent from the control unit ₁₃ to the first fuel injection valve ₁₂₁ . Output. As a result, as shown in Fig. 6a, when the throttle opening increases at a slope above a certain level,
That is, during acceleration, the first fuel injection valve 12 ₁ temporarily injects fuel, and the acceleration increase fuel is supplied into the first intake passage 10 ₁ . After outputting the temporary pulse x ₁ ', the control unit 13 resets the temporary pulse flag T to 0 and clears the time counter value t in steps Q ₁₃ and Q ₁₄ .

Here, in step _Q8 above, the time counter value t
>α, the reason for calculating or determining the average rate of change of the throttle opening θ in step Q ₉ is because it is difficult to accurately read the rate of change of the throttle opening in the extremely short time of one cycle. It is. Also, the reason why the time counter value t is cleared in step _Q14 after outputting the temporary pulse _x1 ' is because even if the acceleration state continues, if the temporary pulse is output for each cycle, fuel will be oversupplied. Therefore, once the temporary pulse x ₁ ' is output, the average rate of change θ is calculated when the count value t exceeds α again from 0, and if the acceleration state is still continuing at that point. The next temporary pulse x ₁ ′ is output only when
However, if θ・<β is determined in step _Q9 , the counter value t is not cleared, so θ・≧β
The calculation and determination of the average rate of change θ· is performed in step _Q9 every time until the value θ is reached.

Incidentally, at the time of starting, the idle switch 18 is switched from ON to OFF, and a signal _S6 indicating this is input to the control unit 13. At this time, the control unit 13 executes steps _Q4 to _Q5 for one cycle immediately after the switch 18 is switched, and sets the temporary pulse flag T to 1. Therefore, as shown in FIG. 6e, even when the average rate of change θ· of the throttle opening is less than the set value β, the temporary pulse x ₁ ″ is applied to the first fuel injection valve 12 ₁ to perform increased fuel injection. In that case,
If the idle switch 18 detects the switching of the throttle valve 15 from closed to open, the temporary pulse x ₁ '' is output not only when the vehicle starts, but also when the accelerator pedal is depressed during driving. become.

Incidentally, the characteristics of the injection amount with respect to the applied pulse of the fuel injection valve generally exhibit a tendency as shown in FIG. That is, region A where the applied pulse width is relatively large.
In this case, an amount of fuel that accurately corresponds to the pulse width is stably injected, but in region B where the applied pulse width is small, it is difficult to control the injection amount and the characteristics become unstable.

However _, as described above, since the increased injection amount during _acceleration by the temporary _pulse ) x ₁ ' is applied, and the injection amount corresponds precisely to the pulse width.

This increased injection during acceleration is carried out by the first fuel injection valve 1 installed in the first intake passage 10 ₁ for low-load conditions where the shutter valve 11 is not provided.
2 ₁ , the flow path area of the first intake passage 10 ₁ is narrow and the flow rate of the intake air is high, so the increased amount of fuel during acceleration is supplied to the intake air having a high flow rate. Then, the fuel is quickly supplied to the combustion chamber. Therefore, good acceleration response can be obtained. In addition, since the first intake passage 10 ₁ is always open regardless of the magnitude of the load, opening of the shutter valve 11 is not necessary, as in the case of increasing injection amount by the fuel injection valve _{12 2 on} the second intake passage 10 2. This problem does not occur if the increased amount of fuel injected is delayed and the increased amount of fuel is not supplied to the combustion chamber.

In the embodiment shown in FIG. 2, an intake pipe 7 having a surge tank portion 8 is used, but in this case, the length and cross-sectional area of each intake passage 10 ₁ and 10 ₂ must be set appropriately. This makes it possible to effectively utilize intake inertia to improve filling efficiency.

(Effects of the Invention) As described above, according to the present invention, for one combustion chamber, the first intake passage, which is always open, and the second intake passage, which is shut off at low load by the shutter valve, are independent of each other. In an electronic fuel injection engine in which the first intake passage is opened and each intake passage is provided with a fuel injection valve, an increase pulse is applied to the fuel injection valve installed in the first intake passage which is always open during acceleration. The injection valve injects an amount of fuel that accurately corresponds to the pulse width of the applied pulse, and this fuel is reliably supplied to the combustion chamber without delay. This prevents disturbances in the air-fuel ratio when increasing the amount of fuel for acceleration, resulting in stable combustion and good acceleration performance.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of the present invention, Fig. 2 is a system diagram showing an embodiment of the invention, Figs. 3 and 4 are flowcharts showing the operation of the embodiment, and Fig. 5 is a system diagram showing an embodiment of the invention. FIG. 6 is a time chart showing the operation of this embodiment, and FIG. 7 is an injection amount characteristic diagram of the fuel injection valve. 2... Combustion chamber, 10 ₁ , 10 ₂ ... First and second intake passages, 11... Shutter valve, 12 ₁ , 12 ₂
. . . Fuel injection valve, 13 . . . Increase pulse application means (control unit), 16 . . . Acceleration detection means (throttle opening sensor).

Claims (1)

[Claims] 1. A first intake passage and a second intake passage are each opened independently for one combustion chamber, and the second intake passage is provided with a shutter valve that closes at low load and opens at high load; This is a fuel control device for an electronic fuel injection engine in which a fuel injection valve is installed in each intake passage, the fuel control device comprising: an acceleration detection means for detecting acceleration of the engine; and when the acceleration detection means detects acceleration, the first intake passage; 1. A fuel control device for an electronic fuel injection engine, comprising: an increasing pulse applying means for applying an increasing pulse of injection amount to a fuel injection valve installed in the fuel injection valve.