JPH0617663B2 - Fuel injection timing control device - Google Patents

Description

The present invention relates to a fuel injection timing control device for an engine.

(Prior Art) Conventionally, in order to precisely control the fuel injection amount supplied to each cylinder of an engine, an injector is provided in the intake passage of each cylinder on the downstream side of the intake manifold to inject fuel at appropriate timing. For example, in Japanese Patent Laid-Open No. 57-108428, fuel injection and supply of an engine for injecting fuel into the intake passage at the end of the intake stroke of each cylinder to promote vaporization of the fuel is disclosed. The device is described.

However, as long as the fuel is injected into the intake passage, if the fuel is injected at an early point in time, such as at the end of the intake stroke, a considerable portion of the injected fuel will adhere to the wall surface of the intake passage, which will cause a time delay. The phenomenon of being inhaled occurs.

However, since the fuel adhering to the wall surface is also sucked in a fixed amount with a certain delay during steady operation, no particular problem occurs, but during transient operation such as acceleration, the fuel supply response is the amount of fuel adhering to the wall surface. There is a delay, and as a result, the acceleration performance deteriorates.

(Problems to be Solved by the Invention) Like the fuel injection supply device of the above publication, when the fuel injection timing is set to a time other than the intake stroke, the fuel is cut during deceleration or downhill traveling. At the time of returning from the cut, there is a problem that not only the return response is significantly deteriorated due to the response delay of the fuel supply, but also the minimum rotation speed (return rotation speed) at the time of the fuel cut has to be set higher. Therefore, if the fuel injection timing is uniformly set in the intake stroke, the above problem can be solved, but in this case, the time from injection to intake becomes short, the fuel is difficult to vaporize in the intake passage, and the fuel performance deteriorates. .

(Object of the Invention) The present invention has been made to solve the above problems, and enhances the return response from the stop of fuel injection while promoting the vaporization and atomization of the injected fuel in the steady operation state. It is an object of the present invention to provide a fuel injection timing control device capable of improving fuel efficiency.

(Structure of the Invention) As shown in FIG. 1, a fuel injection timing control device according to the present invention is provided with an operating state detecting means for detecting an operating state of a multi-cylinder engine and an intake passage corresponding to each cylinder. A fuel injection timing control device having a fuel injection valve for controlling the fuel injection timing for injecting fuel from the fuel injection valve for each cylinder, and decelerating based on the output of the operating state detection means. Based on the output of the operation state detection means and the determination means for determining whether the fuel injection is stopped or canceled during operation, the fuel injection timing of each cylinder is set to a timing other than the intake stroke in the steady operation state and Immediately after the injection stop is released, fuel injection timing setting means for setting the intake stroke is provided.

(Operation) In the fuel injection timing control device according to the present invention, the determination means determines whether the fuel injection is stopped or released during deceleration operation based on the output of the operation state detection means. Then, the fuel injection timing setting means sets the fuel injection timing of each cylinder to a timing other than the intake stroke in the steady operation state based on the outputs of the operating state detecting means and the determining means, and immediately after the cancellation of the fuel injection stop. Is set to the intake stroke.

(Effects of the Invention) In the fuel injection timing control device according to the present invention, the fuel injection timing is set to a timing other than the intake stroke in the steady operation state as described above, so fuel vaporization / Atomization can be promoted, and the fuel injection timing is set to the intake stroke immediately after the cancellation of the fuel injection stop, so the fuel is drawn into the intake flow without a response delay, and the return response from the fuel injection stop is improved. It is possible to improve, and it is possible to set the minimum number of revolutions in the fuel injection stopped state to be low to relax the condition for stopping the fuel injection and widen the region of the fuel injection to save the fuel.

(Embodiment) An embodiment in which the present invention is applied to a vertical four-cylinder fuel injection engine will be described below with reference to the drawings.

The fuel injection timing control system in this embodiment is the second
Four injectors for each injecting fuel into the intake passage 2 of each cylinder ₁ 1 to 1 ₄ of the engine E as shown in FIG. ₃ 1 to 3
_4, a control unit 4 that outputs a drive signal to the injectors 3 ₁ to 3 _4, essentially constituted by the various sensors described below for outputting various detection signals to the control unit 4.

The throttle opening sensor 5 is connected to the throttle valve 6 and detects the opening of the throttle valve 6 to output a throttle opening signal TH.

The manifold negative pressure sensor 7 is provided on the downstream side of the throttle valve 6 and upstream of the intake manifold 8, and detects the negative pressure of the intake manifold 8 to output a manifold negative pressure signal V.

The crank angle sensor 9 is provided in association with the crank shaft 10 and outputs a crank angle signal C as shown in FIG. 4 (a).

Cylinder identifying sensor 11 is provided by linking the distributor 12, the first cylinder as shown in FIG. 4 (b) 1 ₁
The cylinder identification signal K is output so as to cover a high level between the intake TDC (intake top dead center) and the ATDC 90 ° (90 ° after top dead center).

The control unit 4 is, as shown in FIG.
A computer including an input / output port 13, a central processing unit (CPU) 14, a read only memory (ROM) 15, a random access memory (RAM) 16 and a free running counter 17, a manifold negative pressure sensor 7 and a throttle. Output signal VT from the opening sensor 5
A first input circuit 18 that receives H, and an A / D converter that receives the manifold negative pressure signal V and the throttle opening signal TH from the first input circuit 18 and A / D converts them to output to the input / output port 13. 19, a second input circuit 20 that receives output signals C and K from the crank angle sensor 9 and the cylinder identification sensor 11 and shapes the waveforms of the signals and outputs them to the input / output port 13.
And a rising / falling detection circuit 22 which receives the crank angle signal C whose waveform has been shaped by the second input circuit 20 and detects the rising and falling of the crank angle signal C and outputs an interrupt signal I corresponding to each to the CPU 14. And timers 21 _{1 to} 21 ₄ for receiving a fuel injection signal from the computer to the corner injectors 3 _{1 to} 3 ₄ and outputting a fuel injection pulse f having a timing and time width corresponding to the signal, and each timer 21.
_The drive circuits 23 ₁ to 23 that receive and amplify the fuel injection pulse f from _{1 to} 21 ₄ and output the amplified fuel injection pulse f to the injectors 3 _{1 to} 3 ₄ .
₄ and.

Here, the basic idea of this fuel injection timing control system will be described.

First, in the steady operation state, during the exhaust stroke (exhaust AB
DC 90 °: 90 ° after exhaust bottom dead center) to slightly lengthen the time from injection to intake by promoting fuel vaporization and atomization in the intake passage 2, while at the beginning of acceleration and from fuel cut As a general rule, during the transient operation state, such as immediately after the return of the intake stroke, the intake stroke starts early (intake TDC).
By injecting fuel into the fuel tank, the responsiveness of fuel supply is increased.

Then, at the time of switching from the exhaust ABDC 90 ° injection to the intake TDC injection or at the time of switching from the intake TDC injection to the exhaust ABDC 90 ° injection, overlapping fuel injection (cylinder 1 stroke cycle 2
Times injection) to sequentially apply the new injection timing after switching from the cylinders 1 ₁ to 1 ₄ in which completed the last injection since the intake stroke in order to prevent.

Then, when returning from the fuel cut to the release of the fuel cut, there can be no overlapped injection of fuel, so the new injection timing after switching (intake TDC injection) is immediately applied.

As a result, it is possible to improve the return response from the fuel cut and set the minimum rotation speed (return rotation speed) when returning from the fuel cut to a low value of 1000 rpm, for example.

The fuel injection timing is determined by the main routine shown in the flowchart of FIG. 6 based on various detection data indicating the operating state of the engine E, and the fuel injection from the injectors 3 _{1 to} 3 ₄ is performed in the main routine. The interrupt processing routine shown in the flowchart of FIG. 7 is executed during execution of the main routine on the basis of the fuel injection timing obtained in step S6.

However, the interrupt processing is performed by the rising / falling detection circuit 22 at the rising and falling edges of the crank angle signal C.
Is executed based on the interrupt signal I output from the CPU to the CPU 14.

The program of the main routine, the program of the interrupt processing routine, and other necessary constants are input and stored in advance in the ROM 15 of the computer.

Next, the main routine (steps S1 to S16) for determining the fuel injection timing will be described with reference to the flowchart of FIG.

First, the input / output port 13 and the RAM 16 are started by the start signal.
When the necessary data stored in the memory is initialized, S
In 1 the throttle opening signal TH is read, and in S2 this throttle opening signal TH and the previous throttle opening T
H is compared, and based on the comparison result, it is determined in S3 whether or not the vehicle is in the accelerating state. If the vehicle is in the accelerating state, the process proceeds to S8 via S4 to S6, and if it is not in the accelerating state, the program proceeds to S8 via S5. Transition.

In S4, it is determined whether the acceleration flag FACC is 1 or 0, and F
When ACC = 0, that is, when acceleration starts, the process proceeds to S6 and S6.
In step S7, the acceleration flag FACC = 1 is set, and in step S7, the intake top injection counter CINJ is set to the intake top injection number NTDC. When the acceleration flag FACC = 1 in S4, that is, when acceleration is being performed from the previous time, the process proceeds to S8.

S5 is a case where the acceleration state is not set, and the acceleration flag FACC is reset in S5.

Since S8 to S11 determine the fuel cut condition,
The manifold negative pressure signal V is read in S8, and the manifold negative pressure is fuel cut determination vacuum F in S9.
It is determined whether or not it is larger than CVAC, and when it is larger, S
When the value is not 10 again, the process proceeds to S13. S10
Then, the engine speed is the fuel cut determination speed FC
It is determined whether or not it is larger than RPM, and when it is larger, S1
When it is not larger than 1, the process proceeds to S13. In S11, it is determined from the throttle opening signal TH whether or not the throttle valve 5 is fully closed. If fully closed, the process proceeds to S12, and if not fully closed, the process proceeds to S13.

In S12, all the conditions for fuel cut are satisfied, and in S12, the fuel cut flag FFC = 1 is set.

S13 is the case that does not correspond to the fuel cut, and S
At 13, it is determined whether the fuel cut flag FFC is 1 or 0, and when FFC = 1, that is, when the fuel cut last time is returned to the state not the fuel cut this time, S
At 14, the fuel cut flag FFC is reset, and at S15, the intake top injection counter CINJ.
The intake top injection number NTDC is set to, and at the time of returning from this fuel cut, in order to immediately shift to the intake top injection, each injector 3 _1-
Injection timing flags FIN _{1 to} FIN corresponding to 3 _4
4 are all set to FIN = 1.

When the fuel cut flag FFC = 0 in S13, the process directly returns.

In the above main routine, the fuel injection timing is set to exhaust ABCDC 90 ° or the intake top injection counter CI.
It is set to intake TDC via NJ.

Next, FIG. 7 for one of determining the fuel injection not to actually injected and the determination of the order of fuel injection of each injector 3 ₁ to 3 ₄ to be made by the interrupt processing at the time of rising or the trailing edge of the crank angle signal C A description will be given based on the flowchart of FIG.

First, when the interrupt processing is started by the interrupt signal I from the rising / falling detection circuit 22, the time is read from the free-running counter 17 in S21, and S
At 22, the engine speed is calculated by obtaining the interrupt cycle from the previous interrupt time and the current interrupt time, the level of the crank angle signal C is read in S23, and the level of the crank angle signal C is "H" or " L "is determined,
When the level of the crank angle signal C is "H", that is, the intake air TD
When C, go to S25, and when "L", that is, ATDC90.
When the angle is °, the process proceeds to S51.

S25 is the case of intake TDC, the cylinder identification signal K is read in S25, it is determined whether the cylinder identification signal K is "H" or "L" in S26, and when it is "H", 1
It is determined that corresponds to the intake TDC turn the cylinder 1 ₁ S
27, and when it is "L", it proceeds to S28.

In S27, the injector counter N = 1 is set, and S
At 28, 1 is added to the injector counter N.

In this way, it is determined by S25 to S28 which of the values of the injector counter N indicating the ignition order corresponds to 1 to 4.

Incidentally, the injector counter N are those corresponding to the subscript of the injector 3 ₁ to 3 ₄ of FIG. 5, Sadamari even cylinder number corresponding thereto when the value of the injector counter N is determined, the cylinder 1 ₁ to 1 ₄ It is understood that this corresponds to the intake TDC of (see FIG. 5).

In S29, it is determined whether or not the intake top injection counter CINJ is 0. When CINJ = 0, that is, when the intake top injection is not applicable, the process proceeds to S30, and in S30, it is determined whether the injector counter N is 1 to 4 or not. And depending on the value of N, shifts to any of S31 to S34,
In each of S31 to S34, each injection timing flag FI
N is reset and set to inject at normal exhaust ABDC 90 °.

In the above S30 to S34, for example, when N = 2, S3
The reason why the injection timing flag FIN ₁ is reset at 2 corresponds to the intake TDC of the _third cylinder 13 when N = 2, and the intake stroke of the _first cylinder 1 ₁ has ended at this point. This is in consideration.

When the intake top injection counter CINJ = 0 is not established in S29, that is, when the intake top injection is set, S
35, the intake top injection counter CINJ is counted down in S35, it is determined in S36 which one of the injector counters N corresponds to, N
Depending on the value of, S37 to S40, S3
In each of 7 to S40, each injection timing flag FIN is set to 1, and the injection top TDC is set to inject.

Even when the transition from the S36, correspondence between the injector counter N and the injection timing counter FIN ₁ ～FIN ₄ is as defined above, intake top injected from the cylinder 1 ₁ to 1 ₄ in which the intake process has been completed at that point in the order Will be switched to.

In the above S24, the level of the crank angle signal C is "L".
At the time of, the process shifts to S51, and from each of the above S31 to S34 and each of the above S37 to S40, shifts to S71.

S51 to S59 are normal injection timings, that is, exhaust AB
It is a routine for determining and executing whether to actually inject at 90 ° DC, and S71 to S79 are routines for determining and executing whether to actually inject at intake TDC.

In S51, the value of the injector counter N is determined, and depending on the value of N at that time, the process shifts to one of S52 to S55, and in each of S52 to S55, it is determined whether each injection timing flag FIN is 1 or 0. It

When shifting from S51, for example, when N = 2, S53
As will be understood from FIG. 5, the determination of the injection timing flag FIN ₃ corresponds to the intake ATDC 90 ° of the _third cylinder 13 when N = 2, and at this time, the fourth cylinder 1 ₄ (injector 3 ₃ Corresponds to) Exhaust ABDC9
This is because the fuel injection timing is 0 °.

In each of S52 to S55, it is determined whether each injection timing flag FIN is 1 or 0, and only when FIN = 0, the process proceeds to S56 to S59, and in each of S56 to S59, the corresponding injector 3 _{1 to} 3 ₄ ( INJ _1- I
Fuel is injected from NJ ₄ ).

That is, since S51 to S59 are for injection at the timing of the exhaust gas ABDC 90 °, injection is performed on condition that FIN = 0.

Therefore, when FIN = 1 is determined in each of S52 to S55, the injection is not performed and the process returns to the main routine.

Next, after S71, when the injection is performed at the timing of intake TDC, the value of the injector counter N is determined in S71, and depending on the value of N, the process proceeds to any of S72 to S75, and in each of S72 to S75. It is determined whether each injection timing flag FIN is 1 or 0.

At the time of transition from S71 to S72 to S75, for example, N
= 2, the injection timing flag FIN in S73
₂ is determined when the current interruption time is the intake TD
Since it corresponds to C, when N = 2, as can be seen from FIG. 5, the third cylinder 1 ₃ corresponding to this injector 3 ₂ corresponds to intake TDC, and FIN ₂ = 1 is set as a condition from the injector 3 _2. This is because it may be jetted immediately.

Fuel is injected from the corresponding injectors 3 _{1 to} 3 ₄ (INJ _{1 to} INJ ₄ ) in each of S76 to S79 only when the result of determination in each of S72 to S75 is FIN = 1. On the other hand, when FIN = 0 is determined in each of S72 to S75, the injection is not performed and the process returns to the main routine.

According to the fuel injection timing control device of the above-described embodiment, in the steady operation state, the fuel can be vaporized and atomized by injecting at the timing of the exhaust ABDC 90 °, such as in the initial stage of acceleration or immediately after the return from the fuel cut. In the transient operation state, the fuel is injected at the timing of the intake TDC and the injected fuel is sucked on the flow of the intake air, so that the adherence to the wall surface of the intake passage is reduced and the responsiveness of the fuel supply is improved.
The acceleration response and the response from the fuel cut can be improved, and the minimum rotation speed in the fuel injection stopped state is set to be low to relax the condition of fuel injection stop and widen the range of fuel injection stop to increase the fuel consumption. You can save money.

Moreover, when switching from the steady operation state to the acceleration state,
Even if the required injection timing is set to the intake TDC injection, the intake TDC is provided on condition that the fuel of the previous injection is taken.
Since the injection is switched to, it is possible to prevent overlapping injection, and since there is no danger of overlapping injection when returning from fuel cut, the required injection timing is the intake TDC.
The return responsiveness can be maximized by switching to the intake TDC injection at the same time that the injection is set.

Incidentally, Fig. 5 shows a stroke and the fuel injection timing of each cylinder 1 ₁ to 1 ₄ of intake, compression, explosion and exhaust when a transition from the fuel cut to fuel cut release (shown in the arrow in the figure) It is an operation time chart.

[Brief description of drawings]

1 shows a functional block diagram of the present invention, FIG. 2 is an overall configuration diagram of a fuel injection timing control system, FIG. 3 is a basic configuration diagram of a control unit, and FIG. FIGS. 5A and 5B are waveform diagrams of the crank angle signal and the cylinder identification signal, FIG. 5 is an operation time chart showing the relationship between the stroke of each cylinder, the fuel injection timing, and the required injection timing, and FIG. 6 is the fuel. FIG. 7 is a flowchart of a main routine for determining the injection timing, and FIG. 7 is a flowchart of an interrupt processing routine. 3 _{1 to} 3 ₄ ... Injector, 4 ... Control unit, 5 ... Throttle opening sensor, 7 ... Manifold negative pressure sensor, 9 ... Crank angle sensor, 11 ... Cylinder identification sensor.

Front Page Continuation (72) Inventor Tetsuro Takaba 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) Reference JP-A-56-34934 (JP, A) JP-A-59-158341 (JP) , A)

Claims (1)

[Claims] 1. A driving state detecting means for detecting a driving state of a multi-cylinder engine, a fuel injection valve arranged in each intake passage corresponding to each cylinder, and a fuel injection timing for injecting fuel from the fuel injection valve. In a fuel injection timing control device having a fuel injection timing control means for controlling each cylinder, a discrimination means for discriminating stop and release of fuel injection during deceleration operation based on an output of the operation state detection means, and an operation state detection A fuel injection timing setting means for setting the fuel injection timing of each cylinder to a timing other than the intake stroke in the steady operation state based on the outputs of the determining means and the determining means, and for setting the intake stroke immediately after the cancellation of the fuel injection stop. Fuel injection timing control device characterized by having