JPS62157257A - Fuel injection device of multicylinder engine - Google Patents

Abstract

PURPOSE:To improve responsiveness when fuel for acceleration is asynchronously injected in response to acceleration requirement by controlling to feed more amount of acceleration fuel to cylinders nearer to the next intake stroke and less amount to cylinders farther to the next intake stroke. CONSTITUTION:When acceleration is required based on an acceleration detection means 21, a control means 22 injects fuel for acceleration asynchronously separately from synchronous injection in which fuel for respective cylinders 1a, 1b... of an engine 1 is periodically metered according to an intake air amount per one cycle to be injected synchronously with the engine revolution from respective injection valves 7. In this case, the amount of injected fuel for the acceleration is controlled so that more fuel is fed to cylinders nearer to the next intake stroke and less fuel to cylinders farther to the next intake stroke according to the length of the time period from the acceleration requirement to the intake stroke of each cylinder. Thus, air-fuel ratio of each cylinder is controlled to the optimum with accuracy, preventing the air-fuel ratio from becoming too rich, improving emission performance, as well as improving acceleration responsiveness.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel injection device for a multi-cylinder engine, and particularly relates to an improvement in a fuel injection device for asynchronously injecting fuel in addition to synchronously injecting fuel during acceleration.

(Prior Art) Conventionally, as a fuel injection device for a multi-cylinder engine, for example, as disclosed in Japanese Patent Publication No. 54-14688,
Each cylinder is equipped with a fuel injection valve that injects 1lJ1 of fuel.
A system is known in which fuel is periodically measured for each cylinder according to the amount of intake air per cycle, and the fuel is injected and supplied to each cylinder in synchronization with engine rotation.

In such a fuel injection system, in order to prevent the air-fuel ratio from changing due to delays in the control system and fuel system at the beginning of acceleration, and to improve acceleration response, the acceleration signal as an acceleration request is At the time of input, in addition to the above synchronous injection, non-synchronous injection is performed.
A fixed amount of acceleration fuel is injected and supplied to all cylinders at the same time.

(Problem to be solved by the invention) However, if acceleration fuel is asynchronously injected into all cylinders at the same time in the same amount at the time of an acceleration request, the length of the period from the acceleration request to the next intake stroke of each cylinder will vary. As a result, the timing at which acceleration fuel is actually drawn into each cylinder varies, and the degree of air-fuel ratio adjustment in each cylinder at that time differs.
This means that the air-fuel ratio of each cylinder during acceleration cannot be precisely controlled.

For this reason, if asynchronous injection m is set to correct the leanness of a cylinder that is close to the next intake stroke from the time of acceleration request, that is, a cylinder with a large degree of lean air-fuel ratio, then the next intake stroke is far from the time of acceleration request. In cylinders, that is, cylinders with a low degree of lean air-fuel ratio, the air-fuel ratio becomes overrich, resulting in deterioration of emission performance. In fact, if the asynchronous injection tJJffi is reduced to a small amount to prevent overriching in the cylinders that are far from the next intake stroke, lean prevention correction for the cylinders that are close to the next intake stroke will not be able to be performed sufficiently, causing acceleration and It will make things worse.

The present invention has been made in view of this point, and its purpose is to avoid distributing the same amount of non-identical 1J11 injection to each cylinder at the time of an acceleration request, and to By changing the ratio according to the length of the period until the intake stroke, the air-fuel ratio can be precisely controlled according to the leanness of each cylinder, thereby improving acceleration response and preventing deterioration of emission performance. .

(Means for solving the problem) In order to achieve the above object, the solving means of the present invention is as follows:
As shown in the figure, each cylinder is equipped with a fuel injector 7 for injecting fuel, and each cylinder is equipped with a fuel injection valve 7 for injecting fuel per cycle. The fuel for each cylinder according to the amount of air is periodically metered and injected to each cylinder in synchronization with the engine rotation, while during acceleration, acceleration fuel is asynchronously injected into all cylinders in addition to the above synchronous injection. As a fuel injection tJJ device for a multi-cylinder engine configured to simultaneously inject and supply fuel, it includes an acceleration detection means 21 that detects when acceleration is requested, and receives the output of the acceleration detection means 21, The fuel injection valves are controlled so that the acceleration fuel injection amount is increased for cylinders close to the next intake stroke and decreased for cylinders far from the next intake stroke, depending on the length of time until the next intake stroke. The configuration includes a control means 22 and the like.

(Function) With the above configuration, in the present invention, when acceleration is requested, the fuel for each cylinder according to the intake air per cycle is periodically measured and injected in synchronization with the engine rotation. Separately, asynchronously, depending on the length of the period from the acceleration request to the next intake stroke of each cylinder, cylinders close to the next intake stroke have more acceleration fuel injection 17J, and cylinders far from the next intake stroke have less Since the acceleration fuel is actually inhaled into each cylinder, the air-fuel ratio of each cylinder is lean based on the synchronous injection, that is, the cylinder near the next intake stroke is lean. This compensates for the fact that the degree of leanness is small in cylinders where the I loss is large and is far from the next intake stroke, and the air-fuel ratio of each cylinder during acceleration is controlled appropriately and accurately. Ru.

As a result, acceleration response is improved, and over-rich air-fuel ratio is prevented, resulting in improved emission performance.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 shows the overall schematic structure of a fuel injection device for a four-cylinder engine according to an embodiment of the present invention. In the same figure, 1 is the first
-A fourth engine having four cylinders 1a to 1d, 2 is a main intake passage whose upstream end opens to the atmosphere through an air cleaner 3 and supplies intake air to the 6 air fa1a to 1d of the engine 1. A surge tank 4 as an intake expansion chamber is provided downstream of the main intake passage 2, and first to fourth independent intake passages 2a to 2d are connected to each cylinder 1a to 1d from the surge tank 4. It is branched, and each cylinder has one
It communicates independently with a to 1d.

The main intake passage 2 is provided with a throttle valve 6 that controls the amount of intake air, and each of the independent intake passages 28 to 2d downstream thereof is provided with a fuel injection valve 7 that supplies 11 DI of fuel. has been done. Further, the main intake passage 2 is connected to the upstream and downstream sides of the throttle valve 6 by bypassing the throttle valve 6, and bypasses the throttle valve 6 to supply auxiliary air to each cylinder 1a to 1d of the engine 1. A passage 8 is provided, and an on-off valve 9 for opening and closing the bypass passage 8 is disposed in the middle of the bypass passage 8.

On the other hand, 10 is an air 70-senna disposed upstream of the throttle valve 6 in the main intake passage 2 and detects the amount of intake air;
12 is an intake air temperature sensor disposed upstream of the throttle valve 6 in the main intake passage 2 to detect the temperature of intake air (intake air temperature);
A throttle opening sensor with a built-in idle switch detects the idling state when the engine is fully closed, and a crank angle sensor 13 detects the crank angle of the engine 1. The outputs of these sensors 10 to 13 can be input to a control unit 20 consisting of a CPU that controls the operation of the fuel injection J valve 7 and opening/opening valve 9.The control unit 20 controls engine operation. Controls each fuel injection valve 7 according to the state to control fuel output from the fuel injection valve 7
In addition to adjusting Jffi, the opening/closing valve 9 is duty-controlled in accordance with the engine operating state to adjust the auxiliary air flow rate through the bypass passage 8.

Next, to explain in detail the control of each fuel injection valve 7 by the control unit 20, during steady operation, fuel is periodically metered into each cylinder 1a to 1d according to the amount of intake air per cycle. , synchronous injection control is performed in which the fuel is injected and supplied from each fuel injection valve 7 to each independent intake passage 28 to 2d in synchronization with engine rotation, while at the time of acceleration request, acceleration fuel is asynchronously supplied separately from the synchronous injection. 1'jl
Asynchronous injection control is performed in which the fuel is simultaneously injected and supplied to all cylinders 1a to 1d. This asynchronous injection control is interrupted when an acceleration request signal is input during the synchronous injection control, and its operation is performed as shown in FIG.

In FIG. 3, each cylinder 1a to 1d is set to the first
The fuel injection valve 7 of each cylinder group is divided into two cylinder groups and a second cylinder group.
First, in step S+, the throttle opening change Δθ from the throttle opening sensor 12 is 1.
It is determined whether or not the value is equal to or greater than a predetermined value α corresponding to 100 at the 11th speed, or whether the idle switch has changed from ON to OFF, and when this determination is YES, it is determined that acceleration is requested, In the next step S2, the current crank angle C^ (at the time of acceleration request) is read, and each cylinder is set to the first cylinder depending on the length of the period from this crank angle CA to the crank angle of the next intake stroke of each cylinder. group and the second cylinder group, and find the periods II and 12. Then, the process proceeds to step S3, where the magnitudes of the periods 1 and 12 are compared and determined, and the period 1+ of the first cylinder group is the period I of the second cylinder group.
If r+<12, which is YES, in step S4, the asynchronous copper pulse width TACCI of the fuel injection valve 7 of the first cylinder group is changed to the preset injection pulse width B, and the second cylinder group is changed to the preset injection pulse width B. The asynchronous injection pulse width TA c C2 of the fuel sniffing valve 7 is set to an injection pulse width A (xB) smaller than the injection pulse width B. On the other hand, if the determination in step S3 is NO such that the period 11 of the first cylinder group is larger than the period ■2 of the second cylinder group, It>12,
In step S5, contrary to the above, the asynchronous injection pulse width TACC+ of the fuel injection valve 7 of the first cylinder group is set to eight, and the second
Asynchronous injection pulse width TA c of fuel injection valve 7 of cylinder group
Set C2 to B. After that, in the next step S6,
Asynchronous injection pulse width TAC to the fuel injection valve 7 of the first cylinder group
The CI signal and the asynchronous injection pulse width TA c C2 signal are respectively outputted to the fuel injection valves 7 of the second cylinder group to drive each fuel injection valve 7 . Note that if the determination in step S1 is No, which is not when an acceleration request is made, the above operation is not executed.

In the above flow, step Sz constitutes the acceleration detection means 21 that detects when acceleration is requested, and
Through steps 82 to S6, depending on the length of the period 11.12 from the acceleration request to the next intake stroke of each cylinder group at the time of acceleration request, as shown in FIG. A control means 22 is configured to control each fuel injection valve 7 so that the acceleration fuel injection amount 4 is increased in the cylinder group, and the acceleration fuel injection amount is decreased in the cylinder group far from the next intake stroke. ing.

Therefore, at the initial stage of acceleration, the synchronous injection method measures fuel per each cylinder 1a to 1d according to the amount of intake air per cycle and injects it to each cylinder 1a to 1d in synchronization with the engine rotation. The degree of leanness of the air-fuel ratio is large in cylinders that are close to the next intake stroke from the time of acceleration request, and the degree of leanness of the air-fuel ratio is small in cylinders that are far from the next intake stroke. On the other hand, when an acceleration request is made, depending on the length of the period from the acceleration request to the next intake stroke of each cylinder, the amount of fuel injected for acceleration is large in the cylinder that is close to the next intake stroke, and the amount of fuel injected for acceleration is large in the cylinder that is far from the next intake stroke. Asynchronous injection is performed to reduce the amount of fuel in the cylinder, so
This corresponds to and compensates for the degree of leanness of the air-fuel ratio based on the above-mentioned synchronous injection when this acceleration fuel is actually taken into each cylinder 1a to 1d, and the air-fuel ratio of each cylinder is adjusted appropriately and accurately. can be controlled. This not only improves acceleration response but also prevents overriching in cylinders that are far from the next intake stroke (cylinders with a small degree of lean) and improves emission performance. can do.

In the above embodiment, a four-cylinder engine is divided into two groups of cylinders according to the period from the acceleration request to the next intake stroke, y, 0, and the cylinder group near the next intake stroke is not accelerated. However, the engine's JJ
Depending on the JH speed performance, the +J0 speed fuel injection limit may be set to zero for a cylinder group as far away as the next intake 11, as shown in FIG. 4(d).

Also, as shown in Fig. 4<a>, each cylinder stone has 'In'.
The legal fuel injection amount may be roughly controlled so that it is large in cylinders that are close to the next intake stroke and gradually decreases in cylinders that are far from the next intake stroke, or as shown in Fig. 4 (b). The fuel injection amount for acceleration may be set to zero in cylinders that are far from the intake stroke.

Further, the present invention is not limited to the four-cylinder engine as in the above embodiment, but can be widely applied to a fuel injection device that performs asynchronous injection in addition to synchronous injection at the D11 speed in other multi-cylinder engines.

(Effects of the Invention) As explained above, according to the present invention, when accelerating fuel is injected asynchronously when acceleration is requested, a large amount of accelerating fuel is injected into a cylinder close to the next intake stroke, and a large amount of accelerating fuel is injected into a cylinder far away. Since it is controlled to reduce the amount of V5, it is compensated according to the degree of leanness of the air-fuel ratio of each cylinder at the initial stage of acceleration, and the air-fuel ratio of each cylinder can be effectively controlled, improving acceleration response. It is possible to achieve both improvement in emission performance.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of the present invention. 2 to 4 show an embodiment of the present invention, FIG. 2 is a diagram showing its overall schematic structure, FIG. 3 is a flowchart showing the operation of asynchronous injection control by the control unit, and FIG.
) to (d) are acceleration fuel injection D for each cylinder, respectively.
It is an explanatory diagram showing an example of the aspect of Affi. DESCRIPTION OF SYMBOLS 1... Engine, 1a-1d... Cylinder, 7... Fuel sentry valve, 20... Control unit, 21...
- Acceleration detection means, 22... control means. Figure 4Figure 3

Claims (1)

[Claims] (1) Equipped with a fuel injection valve that injects fuel for each cylinder, 1
While the fuel for each cylinder is periodically measured according to the amount of intake air per cycle and injected to each cylinder in synchronization with the engine rotation, during acceleration, all the acceleration fuel is asynchronously supplied in addition to the above synchronous injection. A fuel injection device for a multi-cylinder engine configured to inject and supply fuel to cylinders simultaneously, comprising an acceleration detection means for detecting when acceleration is requested, and receiving an output of the acceleration detection means,
When an acceleration request is made, depending on the length of the period from the time of the acceleration request to the next intake stroke of each cylinder, the amount of fuel injection for acceleration is increased for cylinders that are close to the next intake stroke, and for cylinders that are far from the next intake stroke. 1. A fuel injection device for a multi-cylinder engine, comprising: control means for controlling each of the fuel injection valves so as to reduce the number of fuel injection valves.