JPH0660585B2 - Fuel injector for multi-cylinder engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for a multi-cylinder engine, and more particularly to an improvement of a fuel injection device that performs asynchronous injection separately from synchronous injection during acceleration.

(Prior Art) Conventionally, in a fuel injection device of a multi-cylinder engine,
A fuel injection valve for injecting fuel into each cylinder is provided, and the fuel injection amount per cylinder according to the intake air amount per cycle is calculated on a regular basis, and the calculated fuel injection amount is synchronized with the engine rotation. It is known that synchronous injection is performed for each cylinder.

In such a fuel injection device, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Laid-Open No. 4-116522, in order to prevent the air-fuel ratio from becoming lean due to the delay of the control system and the fuel system at the initial stage of acceleration and improve the acceleration response, at the time of inputting an acceleration signal as an acceleration request. In addition to the above-mentioned synchronous injection, a fixed amount of fuel for acceleration is injected into all cylinders at the same time asynchronously.

However, when the same amount of acceleration fuel is simultaneously injected into all cylinders at the same time when an acceleration request is made, the acceleration fuel is actually injected into each cylinder due to the length of the period from the acceleration request to the next intake stroke of each cylinder. Since the intake timing is different and the fuel demand corresponding to the filling amount of each cylinder at that time is different, the air-fuel ratio of each cylinder cannot be accurately controlled during acceleration. Therefore, if the asynchronous injection amount is set to be small based on the cylinder with a short period from the acceleration request to the next intake stroke, the air-fuel ratio becomes lean in the cylinder with a long period from the acceleration request to the next intake stroke, On the contrary, if a large amount of asynchronous injection is set based on a cylinder that has a long period from the acceleration request to the next intake stroke, the air-fuel ratio will be increased in the cylinder with a short period from the acceleration request to the next intake stroke. Became overrich and could not solve problems such as shock or hesitation during acceleration.

(Object of the invention) Therefore, according to the present invention, when the acceleration request is made, the asynchronous injection amount to each cylinder is not made equal, but is changed according to the length of the period from the acceleration request to the next intake stroke of each cylinder. An object of the present invention is to provide a fuel injection device for a multi-cylinder engine with improved acceleration response.

(Structure of the Invention) As shown in FIG. 1, the fuel injection device of the present invention includes a fuel injection valve 7 for injecting fuel into each cylinder 1a, 1b, 1c, ... The fuel injection amount for each cylinder according to the intake air amount is calculated on a regular basis, and the calculated fuel injection amount is synchronized with the engine rotation to perform synchronous injection for each cylinder 1a, 1b, 1c. In a fuel injection device for a multi-cylinder engine, which is configured to inject fuel for acceleration simultaneously in all cylinders asynchronously with the synchronous injection, the acceleration detection means 21 for detecting an acceleration request time and the acceleration detection means 21 A period detecting means 22 for detecting the length of the period from the acceleration request time to the next intake stroke for each cylinder based on the output, and this period detecting means 2
Based on the output of 2, when the acceleration is requested, the injection amount of the acceleration fuel in the cylinder having a long period until the next intake stroke is larger than the injection amount of the acceleration fuel in the cylinder having a short period until the next intake stroke. The control means 23 for controlling each fuel injection valve 7 is provided.

(Advantages of the Invention) With the above configuration, it is possible to increase the fuel injection amount corresponding to the required amount of each cylinder of the engine during acceleration, and to prevent shock and hesitation during acceleration.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 shows an overall schematic structure of a fuel injection device for a four-cylinder engine according to an embodiment of the present invention. In FIG. 2, reference numeral 1 is an engine having four cylinders 1a to 1d of first to fourth,
Reference numeral 2 is a main intake passage for supplying air to each cylinder 1a to 1d of the engine 1 by opening an upstream end to the atmosphere through an air cleaner 3, and downstream of this main intake passage 2 is an intake expansion chamber. A surge tank 4 is provided, and first to fourth independent intake passages 2a to 2d are branched from the surge tank 4 corresponding to the cylinders 1a to 1d.
It independently communicates with a to 1d.

A throttle valve 6 for controlling the intake air amount is arranged in the main intake passage 2, and a fuel injection valve 7 for injecting and supplying fuel to each of the independent intake passages 2a to 2d downstream thereof.
Is provided. Further, the main intake passage 2 is provided with a bypass passage 8 which bypasses the throttle valve 6 and supplies auxiliary air to the cylinders 1a to 1d of the engine 1.
A control valve 9 for controlling the amount of air passing through the bypass passage 8 is arranged in the middle of the bypass passage 8.

An air flow sensor 10 for detecting the intake air amount and an intake temperature sensor 11 for detecting the temperature of the intake air are arranged upstream of the throttle valve 6 in the main intake passage 2. Further, 12 detects the opening of the throttle valve 6 and
Throttle opening sensor with a built-in idle switch that detects when the throttle valve 6 is fully closed as idling time, 13
Is a crank angle sensor for detecting the crank angle of the engine 1. The outputs of the sensors 10 to 13 are input to a control unit 20 including a CPU that controls the operation of the fuel injection valves 7 and the control valve 9, and the control unit 20 controls the fuel injection valves according to the engine operating state. 7, the fuel injection amount from these fuel injection valves 7 is adjusted, and the control valve 9 is duty-controlled to adjust the auxiliary air flow rate through the bypass passage 8.

Next, each fuel injection valve 7 by the control unit 20
In the steady operation, the fuel injection amount for each cylinder according to the intake air amount per cycle is calculated on a regular basis, and the calculated fuel injection amount is synchronized with the engine rotation. While performing synchronous injection control of injecting and supplying from the valve 7 to each of the independent intake passages 2a to 2d, when acceleration is requested, fuel for acceleration is simultaneously and asynchronously supplied to all cylinders 1a to 1d asynchronously with the synchronous injection. Asynchronous injection control is performed. In that case, the crank angle CA at the time of acceleration request is read, and this crank angle C is read.
According to the length of the period from A to the crank angle of the next intake stroke of each cylinder, each cylinder is divided into a first cylinder group and a second cylinder group,
The periods I ₁ and I ₂ are calculated. 3 (a) shows the synchronous injection pulse P1 for the first cylinder group, and FIG. 3 (b) shows the second injection pulse P1.
The synchronous injection pulse P2 for the cylinder group is shown. Fig. 3
(c) shows the opening of the throttle valve 6 detected by the throttle opening sensor 12, and FIG. 3 (d) shows the filling amount. As an example of a method for determining the length of the periods I ₁ and I ₂ , first, as shown in FIGS.
Signals G1 and G2 representing the top dead center of each of the first cylinder group and the second cylinder group generated for each CA (crank angle).
Is detected by the crank angle sensor 13, and these signals G1 and G
From FIG. 2, as shown in FIG. 3 (g), a pulse signal P3 which becomes "1" by the signal G2 and "0" by the signal G1 is created. If the acceleration request time t is within the "1" area of the pulse signal P3, it is determined that I ₁ <I _2, and if the acceleration request time t is within the "0" area of the pulse signal P3, I ₁ > I. _It may be judged as ₂ . When the acceleration request time t is within the region of "1" of the pulse signal P3 as shown in FIG. 3 (g), the fuel injection of the first cylinder group is performed as shown in FIG. 3 (h). The pulse width of the asynchronous injection pulse P10 for the valve 7 is set to a preset injection pulse width A, and as shown in FIG. 3 (i), the asynchronous injection pulse P20 for the fuel injection valve 7 of the second cylinder group is set. The pulse width is set to an injection pulse width larger than the injection pulse width A. 3 (i ')
In order to give a margin to the asynchronous injection condition determination time,
The case where the asynchronous injection in FIG. 7 (i) is divided into two times is shown, and when the fuel injection valve 7 acceleration request of the second cylinder group is requested, the pulse width of the asynchronous injection pulse P20 ′ for the fuel injection valve 7 of the second cylinder group is The injection pulse width A equal to that of one cylinder group is set to perform the first asynchronous injection, and then A + B '
The second injection is performed by the asynchronous injection pulse P20 'having the pulse width B'that satisfies the condition of = B.

Next, FIG. 4 shows a flow of asynchronous injection control of each fuel injection valve 7 by the control unit 20. This asynchronous injection control is interrupted when a signal at the time of acceleration request is input during the synchronous injection control. First, step S1
Then, it is determined whether the change Δθ in the throttle opening from the throttle opening sensor 12 exceeds a predetermined value α corresponding to acceleration, or whether the idle switch has changed from ON to OFF. If YES, it is determined that acceleration is requested, and in the next step S2, the crank angle CA at that time is read and the pulse signal P3 is created. Then, in the next step S3, the length relationship between the periods I ₁ and I ₂ is determined depending on whether the acceleration request time t is in the region of “1” of the pulse signal P3 or in the region of “0”, If I ₁ <I ₂ , then in step S4 the first
The asynchronous injection pulse width for the fuel injection valve 7 of the cylinder group is set to a preset injection pulse width A, and the asynchronous injection pulse width for the fuel injection valve 7 of the second cylinder group is larger than the injection pulse width A. Set to width B. on the other hand,
If the determination result in step S3 is I ₁ > I ₂ ,
In step S5, contrary to step S4, the asynchronous injection pulse width for the fuel injection valve 7 of the first cylinder group is set to the larger B, and the asynchronous injection pulse width for the fuel injection valve 7 of the second cylinder group is set smaller. Set to A. Then, in step S6, the signals of the asynchronous pulse widths set in step S3 or S4 are output to drive the fuel injection valves 7 to inject fuel. If it is determined in step S1 that the acceleration is not requested, the asynchronous injection control is not executed.

In the above flow, the acceleration detecting means 21 for detecting the acceleration request time is constructed in step S1, and step S2,
When the acceleration is requested, the period detection means 22 for detecting the length of the periods I ₁ , I ₂ from the time when the acceleration is requested to the next intake stroke of each cylinder group is constituted by S3, and when the acceleration is requested by steps S4 to S6. Depending on the length of the periods I ₁ and I _2, the fuel injection amount for acceleration is small in the cylinder group having a short period until the next intake stroke, and the acceleration fuel is small in the cylinder group having a long period until the next intake stroke. The control means 23 for controlling each fuel injection valve 7 is configured so as to increase the injection amount.

With the above configuration, the present invention makes it possible to increase the amount of fuel injection commensurate with the engine request amount when acceleration is requested.
It is possible to prevent shock and hesitation during acceleration. The present invention is not limited to the four-cylinder engine as in the above embodiment, but can be widely applied to other multi-cylinder engines to fuel injection devices that perform asynchronous reflection separately from synchronous injection during acceleration.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of the present invention, FIG. 2 is an embodiment of the present invention, FIG. 2 is a diagram showing the overall schematic structure thereof, and FIGS. 3 (a) to (i ') are accelerations. Waveform diagram showing the signal at the time of request, 4th
The figure is a flowchart showing the operation of the asynchronous injection control by the control unit. DESCRIPTION OF SYMBOLS 1 ... Engine, 1a-1d ... Cylinder 7 ... Fuel injection valve 20 ... Control unit 21 ... Acceleration detection means, 22 ... Period detection means 23 ... Control means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junji Umete Shinchi 3-1, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-61-185630 (JP, A) JP-A-59- 51137 (JP, A) JP 60-201046 (JP, A) JP 62-157257 (JP, A)

Claims (1)

[Claims] 1. A fuel injection valve for injecting fuel into each cylinder is provided, and a fuel injection amount per cylinder according to an intake air amount per cycle is calculated on a regular basis, and the calculated fuel injection amount is calculated. In a fuel injection device for a multi-cylinder engine, in which fuel is injected synchronously to each cylinder in synchronism with engine rotation, and at the same time, fuel for accelerating is simultaneously injected into all cylinders asynchronously in addition to the synchronous injection during acceleration, An acceleration detecting means for detecting the time, a period detecting means for detecting the length of the period from the acceleration request time to the next intake stroke for each cylinder based on the output of the acceleration detecting means, and an output of the period detecting means. Based on this, when requesting acceleration,
The fuel injection valves are controlled so that the acceleration fuel injection amount in the cylinder having a long period until the next intake stroke is greater than the acceleration fuel injection amount in the cylinder having a short period until the next intake stroke. A fuel injection device for a multi-cylinder engine, comprising: a control means.