JP3203790B2 - Fuel injection control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for cutting off fuel based on the operating state of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, operating conditions such as the rotational speed of an internal combustion engine and a fully closed state of a throttle valve have been detected. At the time, there is known a fuel cut that stops fuel injection to the internal combustion engine.

[0003] When the vehicle is driven in an operating state near the condition where the fuel cut is satisfied, for example, during downhill driving, the throttle valve is fully closed and the operation of depressing the accelerator pedal is repeatedly performed. , Fuel cut and fuel injection are frequently repeated. Therefore, the torque change of the internal combustion engine becomes large, and the vehicle vibrates back and forth, which is uncomfortable for the driver.

In order to solve this problem, Japanese Patent Publication No.
As described in Japanese Patent No. 14533, the amount of intake air into the intake pipe when the fuel cut condition is satisfied is detected, and when the amount of intake air is smaller than the set amount of intake air, the amount of intake air is reduced from the set amount of intake air. It is known that the delay time is made longer than in the case where the delay time is large.

[0005]

For example, when traveling on level ground at a predetermined speed, the fuel cut condition may be satisfied when the accelerator pedal is slowly returned to decelerate to the fully closed state of the throttle valve. In such a case, the operation in which the accelerator pedal is immediately depressed is rarely performed, and the delay time of the start of fuel cut may be short.

[0006] However, in such a conventional device,
In the operation state, the intake air amount immediately after the throttle valve is fully closed is smaller than the set intake air amount, and the delay time of the fuel cut start is set to a large value after the fuel cut condition is satisfied. In the case shown in FIG. 7, the case where the determination is made based on the intake pipe pressure instead of the intake air amount is shown, but the same applies in that case. Therefore, there has been a problem that the improvement in fuel efficiency may not be sufficiently achieved.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel injection control device which aims to solve the above-mentioned problems and further improves fuel efficiency.

[0008]

In order to achieve the above object, the present invention has the following structure as means for solving the problems. That is, as illustrated in FIG. 1, a fuel injection amount corresponding to an operation state of the internal combustion engine M1 is calculated based on a control program stored in advance, and fuel injection to the internal combustion engine M1 is controlled based on the calculated value. Fuel injection control means M2
And a fuel cut determining means M for detecting an operating state of the internal combustion engine M1 and determining a fuel cut based on the operating state.
3 and a fuel cut control means M4 for controlling the fuel injection control means M2 when the fuel cut is determined to cut off the fuel after a predetermined delay time has elapsed. Load detecting means M5 for detecting the load of the engine M1, and maximum load detecting means M6 for detecting the maximum value of the load after the previous fuel cut return.
And, when the deviation between the load and the maximum value when the fuel cut is determined is large, the short delay time,
And a delay time setting means M7 for setting the long delay time when the deviation is small.

[0009]

In the fuel injection control device having the above-mentioned structure, the fuel cut determining means M3 detects the operating state of the internal combustion engine M1, and determines the fuel cut based on the operating state. Then, the load detecting means M5 detects the load of the internal combustion engine M1, and the maximum load detecting means M6 detects the maximum value of the load after the previous fuel cut return.

When the fuel cut is determined, the delay time setting means M7 sets a short delay time when the deviation is large and sets a small delay time based on the deviation between the load when the fuel cut is determined and the maximum value. Sometimes a long delay time is set. Further, the fuel cut control means M4 controls the fuel injection control means M2 to cut off the fuel after the elapse of the delay time set by the delay time setting means M7.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a schematic configuration diagram of a fuel injection control device according to one embodiment of the present invention. Reference numeral 1 denotes an internal combustion engine,
An intake pipe 4 and an exhaust pipe 6 which respectively communicate with the combustion chamber 2 in the inside;
The fuel cell system includes a fuel injection valve 8 for injecting fuel into intake air of an intake pipe 4 and a spark plug 10 provided in the combustion chamber 2.

The intake pipe 4 has a throttle valve 14 which opens and closes in response to an accelerator pedal (not shown) from the inlet side to the combustion chamber 2, and a surge tank 16.
Are provided. Further, the intake pipe 4 is provided with a throttle opening sensor 20 that detects an opening of the throttle valve 14 in conjunction with the throttle valve 14 and outputs an ON signal when the throttle valve 14 is fully closed, and a surge tank 16. And an intake pressure detection sensor 22 for detecting the pressure in the intake pipe.

On the other hand, an igniter 28 provided with an ignition coil for outputting a high voltage required for ignition of the ignition plug 10, and a distributor which interlocks with a crankshaft (not shown) and distributes the high voltage generated by the igniter 28 to the ignition plug 10. 30 are provided.

A pulse signal is attached to the distributor 30 and outputs a pulse signal according to the number of revolutions. For example, a pulse signal is outputted every time the distributor shaft 32 that makes one rotation with two rotations of the crankshaft rotates 30 degrees. A rotational speed sensor 34 and a cylinder discriminating sensor 36 that is mounted in the distributor 30 and outputs a reference position signal at a reference position during one rotation, for example, outputs a pulse signal every time the distributor shaft 32 rotates 180 degrees. Have.

Further, an idle speed control valve 40 is provided in a bypass passage 38 bypassing the throttle valve 14.
Is provided. The fuel injection valve 8 and the spark plug 1
0, intake air amount detection sensor 18, throttle opening degree sensor 20, intake pressure detection sensor 22, rotation speed sensor 34, cylinder discrimination sensor 36, and idle speed control valve 40
Are connected to the electronic control circuit 50, respectively.

The electronic control circuit 50 includes a well-known CPU 5
2. An input / output circuit for inputting / outputting from / to the outside, here an input circuit 58 and an output circuit 60, are connected to each other via a common bus 62. The CPU 52 inputs signals from the throttle opening sensor 20, the intake pressure detection sensor 22, the rotation speed sensor 34, and the cylinder discrimination sensor 36 to the input circuit 5
Input via 8. On the other hand, these signals and the ROM 5
4. The CPU 52 calculates a fuel injection amount, an ignition timing, and the like according to the operating state of the internal combustion engine 1 based on the data in the RAM 56 and a control program stored in advance. A drive signal is output to the fuel injection valve 8, the igniter 28, and the idle speed control valve 40 to control the fuel injection and the ignition timing of the internal combustion engine 1. In this embodiment, the electronic control circuit 50 functions as the fuel injection control means M2.

Next, the processing performed in the electronic control circuit 50 will be described with reference to the flowchart of FIG. First, the rotation speed NE detected by the rotation speed sensor 34 is set to a preset rotation speed NEFCUT.
(For example, 1500 rpm) or not (step 100). If the rotational speed NE is smaller than the set rotational speed NEFCUT, it is determined that the fuel cut condition is not satisfied, and a fuel cut condition flag XFCUT described later is cleared (step 108).

If the number of revolutions NE is equal to or greater than the set number of revolutions NEFCUT (step 100), then it is determined whether or not a fully closed ON signal has been input from the throttle opening sensor 20 (step 102). If not, it is determined that the fuel cut condition is not satisfied, and the intake pressure detection sensor 22
It is determined whether or not the intake pipe pressure PM detected by the above is greater than the maximum value PMMAX of the intake pipe pressure (step 104).

If the intake pipe pressure PM exceeds the maximum value PMMAX, the intake pipe pressure PM is substituted as a new maximum value PMMAX (step 106), and then the fuel cut condition flag XFCUT is cleared (step 108). . On the other hand, when the maximum value PMMAX is not exceeded, the fuel cut condition flag XFCUT is cleared without updating the maximum value PMMAX (step 10).
8). Thereafter, the control process is repeatedly executed.

If it is determined in steps 100 and 102 that the rotational speed NE is equal to or higher than the set rotational speed NEFCUT and the throttle opening sensor 20 is on,
It is determined that the fuel cut condition is satisfied, and it is determined whether a fuel cut condition flag XFCUT is 0 (step 110).

If it is 0, that is, it is determined that the control is the first control, first, the fuel cut condition flag XFCUT is set to 1
Is set (step 112). And the maximum value PM
Deviation obtained by subtracting the intake pipe pressure PM from MAX (= PMM
AX-PM) is smaller than a predetermined value DPM (step 114).

When the deviation is smaller than the predetermined value DPM,
It is determined that the throttle is slightly opened / closed from the fully closed state, and a predetermined long time A is set in the delay time TMFCUT (step 116). When the deviation is larger than the predetermined value DPM, the delay time TMFCU
A predetermined short time B shorter than the long time A is set to T (step 118).

Next, a long time A is added to the delay time TMFCUT.
Or, if B is set for a short time, once the maximum value PMMA
X is cleared (step 122). As a result, the maximum value PMMAX becomes equal to the value in step 104, after returning from the fuel cut.
106 is repeatedly executed to obtain the new maximum value PMM.
AX is detected.

That is, once the maximum value PMMAX is cleared once the fuel cut condition is satisfied and the accelerator pedal (not shown) is depressed, it is determined that the vehicle is not turned on by the processing of step 102, and the processing of steps 104 and 106 is repeated. Execute. Therefore, the maximum value PMMAX of the intake pipe pressure PM after returning from the fuel cut is detected, and the maximum value PMAX
MMAX is updated.

After executing the processing of step 122, it is next determined whether or not the delay time TMFCUT is 0 (step 124).
Is subtracted from (step 126), and this control process is repeatedly executed. If the fuel cut condition is satisfied during the repetitive execution, the process of step 110 determines that the fuel cut condition flag XFCUT is not 0, and does not execute the processes of steps 112 to 122 without executing the processes of steps 112 to 122. Execute the process. And the delay time TM
The process of subtracting 1 from FCUT (step 126) is repeated, and when it is determined that the delay time TMFCUT has become 0 (step 124), a fuel cut is executed (step 128).

If it is determined that the fuel cut condition is not satisfied during the execution of the repetition (step 1).
00, 102), the processing of step 104 and subsequent steps, or the processing of step 108 and subsequent steps are executed. For example, as shown in FIG. 4, when the throttle valve 14 is slightly opened and closed from the fully closed state while traveling on a downhill, the deviation at that time is smaller than a predetermined value DPM, and the delay time TMFCUT is longer than the predetermined value DPM. A is set. Therefore, even if the opening and closing of the throttle valve 14 is repeated in a short time, the delay time TMFCUT
Before (= A) becomes 0 (step 124), the fuel cut condition is not satisfied (steps 100 and 102),
No fuel cut is performed.

As shown in FIG. 5, when the throttle valve 14 is fully closed from a predetermined operation state while traveling on level ground, the deviation at that time is larger than a predetermined value DPM, and the delay time TMFCUT A short time B is set. Therefore, after the fuel cut condition is satisfied, a short delay time T
When MFCUT (= B) has elapsed, the CPU 52 stops outputting the fuel injection signal to the fuel injection valve 8 via the output circuit 60, and the fuel cut is executed (step 128).

Further, as shown in FIG. 6, even if the throttle valve 14 is fully closed and decelerated by gentle operation during traveling in a predetermined driving state, the deviation at that time is larger than a predetermined value DPM. Large and short delay time TMFCUT (=
After B), a fuel cut is executed (step 128).

Judging simply by the intake pipe pressure PM and the like, in such a case, when the fuel cut condition is established, the intake pipe pressure PM becomes smaller as in the case shown in FIG.
As shown in FIG. 7, the delay time TMFCUT has a long time A.
Will be set to However, by judging from the magnitude of the deviation between the intake pipe pressure PM when the fuel cut condition is satisfied and the maximum value PMMAX, whether a slight opening / closing operation of the throttle valve 14 has been performed near the satisfaction of the condition, or It is possible to effectively determine whether a gradual opening / closing operation of the throttle valve 14 has been performed from a predetermined operation state to a fully closed state. Therefore, even in such a case, the fuel cut is performed well, and the fuel efficiency can be further improved.

In the present embodiment, the pressure in the intake pipe PM is detected as the load. However, the present invention can be similarly implemented by detecting the intake air amount and the throttle opening as the load. Also,
In this embodiment, the execution of the processing of the throttle opening sensor 20, the rotation speed sensor 34 and the steps 100 and 102 functions as the fuel cut determination means M3, and the steps 124 and 12 are executed.
It functions as 6,128 fuel cut control means M4.

Further, the intake pressure detecting sensor 22 functions as the load detecting means M5, and the execution of the processing of steps 104 and 106 functions as the maximum load detecting means M6, and
4, 116 and 118 are executed by the delay time setting means M
Work as 7. As described above, the present invention is not limited to such embodiments at all, and can be implemented in various modes without departing from the gist of the present invention.

[0032]

As described in detail above, the fuel injection control device of the present invention determines whether a slight throttle opening / closing near the satisfaction of the fuel cut condition by judging the difference between the load when the fuel cut condition is satisfied and its maximum value. , Or to determine whether the throttle operation is gradual from the specified operating state to full closure.
This has the effect of further improving fuel efficiency.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a basic configuration of a fuel injection control device according to the present invention.

FIG. 2 is a schematic configuration diagram as one embodiment of a fuel injection control device of the present invention.

FIG. 3 is a flowchart illustrating an example of a fuel cut control process performed by the electronic control circuit according to the embodiment.

FIG. 4 is a time chart showing the operation of the fuel injection control device of the present embodiment during downhill traveling.

FIG. 5 is a time chart showing the operation of the fuel injection control device of the present embodiment during traveling on level ground.

FIG. 6 is a time chart showing an operation when a gentle throttle operation is performed by the fuel injection control device of the embodiment.

FIG. 7 is a time chart showing an operation when a gentle throttle operation is performed by a conventional fuel injection control device.

[Explanation of symbols]

M1,1 internal combustion engine M2 fuel injection control means M3 fuel cut determination means M4 fuel cut control means M5 load detection means M6 maximum load detection means M7 delay time setting means 4 intake pipe
14 ... Throttle valve 20 ... Throttle opening sensor 22 ... Intake pressure detection sensor 34 ... Rotation speed sensor 50 ... Electronic control circuit

Claims (1)

(57) [Claims] 1. A fuel injection control means for calculating a fuel injection amount according to an operation state of an internal combustion engine based on a control program stored in advance, and controlling fuel injection to the internal combustion engine based on the calculated value. A fuel cut determining means for detecting an operating state of the internal combustion engine and determining a fuel cut based on the operating state; and when the fuel cut is determined, controlling the fuel injection control means for a predetermined delay time. Fuel cut control means for cutting the fuel after a lapse of time, a load detection means for detecting a load of the internal combustion engine, and a maximum for detecting a maximum value of the load after the previous fuel cut return. Load detecting means, when the difference between the load and the maximum value when the fuel cut is determined is large, the delay time is short, and when the deviation is small, the delay time is long. The fuel injection control apparatus characterized by comprising: a delay time setting means for setting a delay time, a.