JPH02112641A - Fuel injection control device - Google Patents

Abstract

PURPOSE:To prevent a select shock by actuating the second fuel injection amount control means and gradually changing a fuel injection amount, determined by said control means, in accordance with the lapse of time, in the case of trouble being detected in a fuel injection control means determining a fuel injection amount corresponding to an operational condition. CONSTITUTION:An output signal is fetched of an intake pressure detector 12, throttle valve opening detector 14, intake air temperature detector 15, oxygen concentration detector 17 and a water temperature detector 18 into a control circuit 16, and in accordance with an operational condition in that time, a fuel injection amount is obtained in a processing circuit 164 controlling a fuel injection valve 8. While here abnormality is judged for whether or not it is generated in the output signal from the detectors of the pressure detector 12 or the like, when the abnormality is judged, the energization time to the fuel injection valve 8 is set in every several revolution of an internal combustion engine 2 for the transfer time (about 200 to 500msec) to a backup control, and when the time reaches the predetermined backup electrification time, a backup circuit 165 is actuated feeding fuel from the injection valve 8 for the preset backup electrification time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for controlling the fuel injection amount of an internal combustion engine, and is particularly preferably implemented when an abnormality is discovered in the fuel injection control device.

A conventional fuel injection control device is a device that supplies an optimal amount of fuel to the amount of air filled in a cylinder of an internal combustion engine. For example, in a fuel injection control device called the D-Jetronic system, based on the principle that the intake pipe pressure is approximately proportional to the amount of intake air per cycle of internal combustion, the intake pipe pressure and the rotational speed of the internal combustion engine are The amount of intake air is calculated, the optimal fuel injection amount is found for the calculated amount of intake air, and three fuels are injected into the cylinder from the fuel injection valve.

In this way, the intake pipe pressure is an important value for calculating the fuel injection amount, and this value is determined based on the signal from the pressure detector. Therefore, if this pressure detector malfunctions or some abnormality occurs in the signal system from the pressure detector to the control device, it will not be possible to calculate the optimal fuel injection amount, and in the worst case, the fuel injection amount to the cylinder will not be able to be calculated. There is a risk that the patient will be unable to drive a car and become unable to do so. Furthermore, a detector to calculate a more optimal fuel injection amount,
For example, temperature detectors and the like are provided, and an abnormality in these detectors may also lead to abnormal operation of the internal combustion engine.

Therefore, failure detection means have conventionally been provided to detect abnormal operation of various detectors or wire harness disconnections or short circuits, etc. When a failure is detected by this detection means, the normal fuel injection control is stopped. Fuel injection control, so-called backup control, is used to prevent the vehicle from becoming inoperable.

Problems to be Solved by the Invention In the backup control described above, a predetermined constant fuel injection amount is injected into the cylinder regardless of the amount of intake air.

When a failure is detected in the fuel injection control device, the normal fuel injection control is temporarily shifted to backup control. Therefore, during this transition, the fuel injection amount changes suddenly, resulting in discontinuous fuel injection control, resulting in a sudden change in the output of the internal combustion engine.

Problems caused when the intake pressure detector malfunctions as a failure of the fuel injection control device, for example, will be explained below. Fig. 4 is a timing chart for explaining the problems of the conventional fuel injection control device. Fig. 4 (1) shows the output signal waveform of the intake pressure detector, Fig. 4 (2) shows the change in the logical value of the abnormality determination flag F in the fuel injection control device,
FIG. 4(3) shows the change in the fuel injection amount, and FIG. 4(4) shows the change in the output torque of the internal combustion engine.

As shown in FIG. 4 (1), the time Wt until time tll
During time 0, the intake pressure detector is operating normally, but at time L
When the intake pressure detector malfunctions in step 11 and its output value suddenly changes, the fuel injection control device determines that an abnormality has occurred in the intake pressure detector. However, even if an abnormality is detected in the signal from the intake pressure detector, it is not immediately determined that there is a failure, and the failure determination of the intake pressure detector is repeatedly performed during the time Wll from time Lll to time t12. At time t12 after the judgment time W11 has elapsed, the fuel injection side tJg device judges that the intake pressure detector is malfunctioning, and changes the abnormality judgment flag F from logic "0" to logic "," as shown in FIG. 4 (2). 1"
Set to At the same time as setting this abnormality determination flag F to logic "1", the fixed fuel injection time TAU, which is the fuel injection time from the fuel injection valve stored in advance in the fuel injection control device, as shown in FIG. 4 (3), In this way, by switching the fuel injection time to the predetermined fixed fuel injection time TAU at time t12, the output torque of the internal combustion engine is changed to the time t as shown in FIG. 4 (4).
At 12, it drops sharply, resulting in a huge shock throughout the army. Then, the time W1 after time t12
2, the internal combustion engine is operated with a fixed fuel injection time TAU.

In this way, in conventional fuel injection control devices, when a failure is determined, the output torque of the internal combustion engine changes rapidly by rapidly shifting from normal fuel injection control to failure fuel injection control. Vibrations occur in the vehicle body.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel injection control device that reduces vibrations generated in a vehicle body by gradually shifting to fuel injection control in the event of a failure.

Means for Solving the Problems The present invention provides a first fuel injection amount regulating means for determining a fuel f:I injection amount suitable for the operating situation of the internal combustion engine, and a predetermined fuel injection method. a second fuel injector control means for deriving a signal for injecting an amount of fuel; a failure detection means for detecting a failure of the first fuel injection amount control means; and a failure detection means for detecting a failure of the first fuel injection amount control means; From the fuel injection amount at the time of failure detection of the fuel injection amount control means,
The present invention is a fuel injection control device characterized in that it includes a signal generating means for generating a signal that gradually changes a fuel II injection date over time in accordance with the fuel injection amount determined by the fuel injection amount control means.

action In the present invention, the first fuel injection amount control means.

The failure detection means detects a failure occurring in the first fuel injection amount control means, and the second fuel injection amount control means determines a fuel injection amount suitable for the operating conditions of the internal combustion engine. When a failure of the first fuel injection amount control means is detected by the failure detection means, the signal generation means derives a signal for injecting the first fuel injection amount from the fuel injection amount of the first fuel injection amount control means at the time of failure detection. A signal is derived that gradually changes the fuel injection amount as time passes from the fuel injection amount derived by the fuel injection amount control means.

Embodiment FIG. 1 is a block diagram of a fuel injection control device 1 in which the present invention is implemented. The internal combustion engine 2 is provided with a plurality of cylinders 3 (one cylinder is shown as a representative in FIG. 1), and when the piston 4 moves up and down in FIG. 1, negative pressure is generated in the combustion chamber 5. . Due to the generation of this negative pressure,
While the intake valve 6 is open, atmospheric air flows into the combustion chamber 5 together with fuel injected from the fuel injection valve 8 via the intake pipe 7.
be introduced within. The mixture of air and fuel introduced into the combustion chamber 5 is compressed by the piston 4, and the spark plug 9
The air-fuel mixture explodes due to the spark ignition, and the internal combustion engine 2 generates power. The exhaust gas after the explosion is discharged to the atmosphere through the exhaust pipe 11 as the piston 4 rises while the exhaust valve 10 is open.

The intake pipe 7 has a pressure detector 1 for detecting intake pipe pressure.
A throttle valve 13 for regulating the amount of intake air introduced into the combustion chamber 5I is provided upstream of the combustion chamber 5I, and the opening degree of the throttle valve 13 is detected by a valve opening degree detector 14. Furthermore, further upstream of the throttle valve 13,
A temperature detector 15 for detecting the temperature of intake air is installed.
It is being measured.

Pressure detector 12, valve opening detector 14 and temperature detector 1
The output signal of 5 is the input interface 1 of the control circuit 16.
61. Further, an oxygen concentration detector 17 attached to the exhaust pipe 11 detects the oxygen concentration in the exhaust gas, that is, the ratio of air and fuel introduced into the combustion chamber 5, and the air-fuel ratio, and inputs it to the input interface 161. do. Furthermore, a water temperature detector 18 for detecting the temperature of the cooling water of the internal combustion engine 2 is attached to the cylinder block, and its detection signal is input to the input interface 161. A signal for detecting the rotational speed of the internal combustion engine 2 is input to the input interface 161 from the power distributor 19 that supplies an ignition signal to the spark plugs installed at the top of each cylinder.

As described above, the signal input to the input interface 161 is converted into a digital signal by the A/D conversion IA circuit 162 and then stored in the memory 163. The processing circuit 164 calculates the amount of intake air from the intake pipe pressure and the rotational speed of the internal combustion engine 2 stored in the memory 163.
With respect to the obtained intake air amount, the fuel injection amount is determined so that the air-fuel ratio of the air-fuel mixture introduced into the combustion chamber 5 is 14.5, which is the stoichiometric air-fuel ratio. Since fuel is supplied to the fuel injection valve 8 at a constant fuel pressure, the amount of fuel supplied is determined by the energization time of the fuel injection control signal from the control circuit 16 to the fuel injection valve 8.

In addition to the above-described fuel injection control, the processing circuit 164 determines whether or not an abnormality has occurred in the output signal from a detector such as the pressure detector 12. For example, if the pressure detector 12 is -50m
When outputting a voltage equivalent to rn Hg or more,
Alternatively, it is determined that an abnormality has occurred in the pressure detector 12 when it outputs a voltage equivalent to 1000 mm l-1 g or more. Further, if the water temperature detection 2H18 outputs a voltage corresponding to a temperature of 150°C or lower or 150°C or higher, it is determined that there is an abnormality. The same applies when the output signals of the valve opening degree detector 14, temperature detector 15, etc. output values that are normally impossible. Furthermore, if a short circuit or disconnection occurs between these detectors and the control circuit 16, it is also determined to be abnormal.

When the processing circuit 164 detects an abnormal condition, it does not temporarily shift from normal fuel injection control to backup control in the event of a failure, but gradually switches from normal control to backup control as shown in the timing chart of FIG. Move to control.

The backup energization time T AU , , u to the fuel injection valve 8 in the backup control varies depending on the operating state of the internal combustion engine 2 at the time of failure determination. That is, as shown in Table 1, it is determined by an idle switch (not shown) whether or not the internal combustion engine 2 is starting or not and whether or not the accelerator pedal is depressed. ) varies depending on The reason why the energization time is set long at the time of starting is because the internal combustion engine 2 has not been warmed up, and the reason why the energization time is set long when the accelerator pedal is depressed is to output more output torque.

Table 1 and FIG. 2 are timing charts for explaining the operation of this embodiment. FIG. 2 (1) shows the change in the abnormality determination flag F of the processing circuit 164, and FIG.
1＼ failure determination signal waveform, Figure 2 (3) is pressure detector 1
FIG. 2 (4) shows the change in the energization time to the fuel injection valve 8, and FIG. 2 (5) shows the change in the output torque of the internal combustion engine 2.

As shown in FIG. 2(3), the pressure detector 12 operates normally during the time WO, and the processing circuit 164 performs normal fuel injection control, so that the abnormality determination flag is set as shown in FIG. 2121(1). is set to logic "0". but,
At time t1, when an unusual signal is output from the pressure detector 12 as shown in FIG. 2 (3), the processing circuit 164 determines that an abnormality has occurred in the pressure detector 12, and
The time Wl from time 1 to time t2 (for example, 50 +
n5ec), the abnormal state of the pressure detector 12 is repeatedly determined. Therefore, during time W1, pressure sensor 1
Since it is not possible to calculate the energization time to the fuel injector 8 using the output signal of 2, the processing circuit 164 calculates the energization time to the fuel injector 8 at time t1 when the pressure detector 12 generates the abnormal signal. If the pressure detector 12 continues to generate an abnormal signal during the one hour W1 that is continuously used during W1, the processing circuit 164 assumes that the pressure detector 12 is malfunctioning at time t2. Figure 2 (1)
), the abnormality determination flag F is set to logic "1".

When the abnormality determination flag F is set to logic "1", the energization time to the fuel injection valve 8 is the transition time to backup control w
2, for example, between 200 and 500 seams, the internal combustion engine 2
A short energization time is set every 5 rotations or every 50 m5eQ. Backup energization time TAUゎ, predetermined at time t3.

When the time TAU is reached, a failure determination signal is sent to the backup circuit 165 as shown in FIG.

1 is delivered to the fuel injection valve 8/\.

As shown in FIG. 2 (4), during the transition time W2, the energization time to the fuel injection valve 8 is set to gradually become shorter, so that the output of the internal combustion engine 2 shown in FIG. 2 (5) The torque gradually decreases from time t2 to time t3, and a smooth transition to backup control is possible without generating large vibrations in the vehicle body.

The operation of the above processing circuit 164 will be explained in more detail.

FIG. 3 is a flowchart for explaining the operation of the processing circuit 164 of this embodiment. Processing port Vδ164
If no abnormal condition is detected, the routine proceeds from step nl- to step r12, where normal fuel injection control calculations are performed and the fuel injection time TAUo- is calculated. In step rm3, a fuel injection control signal is output to the fuel injection valve 8 during the energization time TAU.

When the processing circuit 164 detects an abnormality in the detector, etc., the process proceeds from step 111 to step rr4, and the abnormality determination time W
If 6 hours Wl, at which it is determined whether or not 1 has ended, has not yet elapsed, the process proceeds to step n5, where the previously output energization time TAU is used as the current energization time TAU, , □, and in step n3 The fuel v1 injection valve 81\fuel injection control signal is output. Step rr 4 , step 5, and step n3 are executed until the abnormality determination time W1 ends.

When the abnormality determination time W1 has elapsed, the process proceeds from step n4 to step n6, where it is determined whether the transition to backup control has been completed or not. If the process has not ended, the process advances to step rr7, where it is determined whether or not it is time to change the energization time. If it is not the change timing, proceed to step ri5'\ and select the previous energization time. When the timing for changing the energization time is t%, proceed from step n7 to step n81\ and change the previous energization time TA.
Backup energization time T A U predetermined by U,
/, it is determined whether or not they match. If they do not match, proceed to step n81\ and calculate the previous energization time TAU.
The magnitude relationship between , and the backup energization time T AU , , u is determined, and if the previous energization time TAU is larger, the process advances to step nlO and the previous energization time TAU is determined.

A predetermined decrease amount α is subtracted from the current energization time T AU −1. Current energization time T
In step rr11, it is determined whether A U , . If they do not match, step n3
The fuel injection amount (1 signal) is output to the fuel injection valve 8 during the current energization time TAU, .

In step rI9, if the previous energization time TAU is smaller than the backup energization time TAU, the process proceeds to step r112, and the previous energization time TAU,
A predetermined increase amount α2 is added to the current energization time T.
A U , , , are calculated. Step r112・
When the current energization time TAU, , is calculated in ,
Proceeding to step nil, the same process as described above is performed, and if the backup energization time T A U b,u does not match, the process proceeds to step 3.

Note that fixed values may be selected for the above-mentioned decrease amount α1 and increase amount α2, or they may be changed over time.

In step rr 11, the current energization time TAU
@ + 1 and backup energization time TAUゎ7. If they match, the process advances to step r113, and a failure determination signal shown in FIG. 2(2) is sent to the backup circuit 165. By sending the failure determination signal of the backup circuit 165/\, the transition from the control by the processing circuit 164 to the backup system (wholesale l\) by the backup circuit 165 is completed. Therefore, when the backup control is performed, the backup energization time TAU,... A fuel injection control signal of . is output to the fuel injection valve 8.

Note that in this embodiment, the backup circuit 165 is provided separately from the processing circuit 164, and backup control is performed in the backup circuit 165, but it may be performed in the processing circuit 164.

In addition, in this embodiment, the so-called D-Jetronic type fuel injection amount (one device has been described, but the invention is not limited to this, and other control devices, such as L-
The present invention can also be effectively implemented in a jetronic fuel injection control device.

Furthermore, in this embodiment, control was explained when an abnormality is detected in the pressure detector 12, but the control is not limited to this. In this case, the present invention can be implemented in the same manner.

Effects of the Invention As described above, according to the present invention, when an abnormality is detected in the fuel injection control means, the predetermined fuel injection amount is gradually increased from the fuel injection amount at the time when the failure was detected. As the torque is changed, the torque output from the internal combustion engine gradually changes, making it possible to suppress vibrations and vibrations that occur in the vehicle body.

[Brief explanation of drawings]

1['3 is a block diagram of the fuel injection control device 1 in which the present invention is implemented, 211W is a timing chart for explaining the operation of this embodiment, and FIG. 3 is the operation of the processing circuit 164 of this embodiment. A flowchart to explain the
FIG. 4 is a timing chart for explaining the problems of the conventional fuel injection control device. DESCRIPTION OF SYMBOLS 1... Fuel '1 injection control device, 8... Fuel f:l injection valve, 12... Pressure detector, 14... Valve opening detector, 1
5...Temperature detector, 16...Control circuit, 17...Oxygen concentration detector, 18...Water temperature detector, 19...Distributor diagram

Claims (1)

[Scope of Claims] A first fuel injection amount control means that determines a fuel injection amount suitable for the operating situation of the internal combustion engine according to the operating situation, and a first fuel injection amount control means that derives a signal for injecting a predetermined fuel injection amount. 2 fuel injection amount control means; a failure detection means for detecting a failure of the first fuel injection amount control means; and a failure detection means for detecting a failure of the first fuel injection amount control means; From the injection amount, the second
1. A fuel injection control device comprising: signal generation means for generating a signal that gradually changes the fuel injection amount determined by the fuel injection amount control means over time.