JPH03185239A - Fuel injection controller at startup time of internal combustion engine - Google Patents

Abstract

PURPOSE:To maintain air-fuel ratios in all cylinders at a proper value and improve startability by performing variable control of fuel injection quantity only at a cylinder which is not started, and approaching the air-fuel ratio of the cylinder which is not started to the proper value gradually. CONSTITUTION:The operation state of a multiple-cylinder internal combustion engine M1 is detected by a means M2. Fuel injection quantity of each cylinder is calculated by a means M3 according to the detected operation state, and the fuel injection quantity at a startup time is variably controlled according to a period from the start of operation. First explosion of each cylinder is detected by a means M4 based on the detected operation state. In any cylinder detected in its first explosion, the variable control of the fuel injection quantity at the startup time is stopped by a means M5. The variable control of the fuel injection quantity is performed only in the cylinders which are not started, so that the air-fuel ratios of the cylinders which are not started are shifted close to the proper value gradually. Consequently, the air-fuel ratios of all the cylinders are maintained to the proper values so as to improve startability.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a microcomputer (hereinafter referred to as "microcomputer") etc. to control the fuel injection amount at the time of starting an internal combustion engine.
The present invention relates to a device for performing IJliIF.

[Conventional technology]

Conventionally, microcontrollers, etc. have been used to control the fuel injection amount of internal combustion engines by 1.
In the case of lltll, the fuel injection amount is increased at the beginning of vJFR to improve startability.

In this case, if the engine does not start even if the engine is cranked for a predetermined period of time or more, and the air-fuel ratio is thought to be over-rich, the fuel injection amount is gradually reduced to prevent the spark plug from being covered with fuel and prevent the over-rich condition. A solution to this problem is described, for example, in Japanese Patent Laid-Open No. 60-3451. Further, it is described in, for example, Japanese Patent Laid-Open No. 173339/1983 that the amount of fuel injection is gradually increased from an over-lean state at the time of starting to maintain an appropriate air-fuel ratio while still being over-lean.

[Problem to be solved by the invention]

In the case of a multi-cylinder engine, some of the cylinders may initially explode even if the golden cylinders do not start, that is, complete explosion does not occur. If the fuel injection amount is controlled to gradually decrease or increase in all cylinders under such conditions, the air-fuel ratio of the cylinder that has already exploded for the first time will become over-lean or over-rich, resulting in a misfire. There was a problem that the target could become unable to start.

The present invention has been made in view of the above points, and it stops variable control of the fuel injection amount according to the period from the start of the cylinder in which the first explosion is detected or the group to which the cylinder belongs, and The purpose is to improve starting performance by setting the fuel ratio to an appropriate value.

[Means to solve the problem]

FIG. 1 shows a diagram of the principle of the present invention.

In the figure, inside the multi-cylinder j! The operating state of the 411SIM 1 is detected by the operating state detecting means M2, and the calculating means M3 calculates the fuel injection tJJffi for each cylinder or each group of cylinders according to the detection result of the operating state detecting means M2, and calculates the fuel injection tJJffi at the time of startup. The fuel injection amount is varied according to the period from the start of the engine.

The first explosion detection means M4 detects the first explosion for each cylinder based on the detection result of the operating state detection means M2.

The fuel injection semi-variable stopping means M5 stops the variable i++ control of the fuel injection amount at the time of startup of the cylinder in which the first explosion has been detected by the first explosion detection means M4 or the group to which the cylinder in which the first explosion has been detected belongs.

[Effect]

In the present invention, for the fuel injection amount of the cylinder in which the first explosion detection means M4 has detected the first explosion or the group to which the cylinder belongs, the fuel injection amount variable stop means M5 stops the variable control of the fuel injection amount of the calculation means M3. In order to ensure that the fuel injection amount is controlled only for cylinders that are not firing for the first time, the air-fuel ratio of the cylinder that has fired for the first time or the group to which that cylinder belongs remains at an appropriate value, and The air/fuel ratio gradually approaches the proper lead, ensuring a golden cylinder start.

〔Example〕

FIG. 2 shows a configuration diagram of an embodiment of a gasoline engine to which the device of the present invention is applied.

In the figure, 1 is the gasoline engine body, 2 is the piston, and 3
is a spark plug, 4 is an exhaust manifold, 5 is an intake manifold, 6 is a surge tank that absorbs the pulsation of intake air, 7 is a throttle valve that adjusts the amount of intake air, 8
is an air flow meter that measures the amount of intake air. The exhaust 7 nibold 4 is provided with an oxygen sensor +j9 that detects the residual oxygen concentration in the exhaust gas, and the intake manifold 5 is provided with a fuel injection valve 10 that injects fuel into the intake air of the gasoline engine body 1. . Intake air temperature sensor 11 detects the temperature of intake air, throttle sensor 12 detects the opening degree of throttle valve 7, and water temperature sensor 13 detects the temperature of gasoline engine cooling water.

Further, the igniter 16 generates the high voltage necessary for ignition and supplies it to the distributor 17, and the distributor 17 distributes and supplies the high voltage to the spark plugs of each cylinder in conjunction with the rotation of the crankshaft (not shown). . The rotation angle sensor 18 outputs a rotation angle signal NE of 24 pulses from the 1st rotation of the distributor 17 to the 12th rotation of the crankshaft, and the cylinder discrimination sensor 19 outputs a rotation angle signal NE of 24 pulses from the 1st rotation of the distributor 17 to the 12th rotation of the crankshaft.
A rotation detection signal G of one pulse is output for each rotation of the motor.

20 is the electric Fi11 control circuit, 21 is the key switch, 22
indicates a starter.

The electronic υI'8 circuit 20 has the configuration shown in FIG. >32 and C
A clock generator (C
LOCK) 33, multiplexer 34, A/D converter 35, input/output ports 36, 37, and output ports 38
．． 39, a shaping circuit 40, and drive circuits 41 and 42, and the CPU 30. ROM31. RAM32. CLOC
K33. Input/output boats 36, 37. Output boat 38.3
9 are mutually connected by a pass line 43.

The multiplexer 34 is supplied with the air flow rate signal from the air 70-meter 8, the water temperature signal from the water temperature sensor 13, the start signal from the starter 21, etc., and sequentially selects each signal. The signals are digitized by the A/DI converter 35, and these digital signals are read by the CP (J30).

The shaping circuit 40 also includes a rotation angle sensor 18. Signals from the cylinder discrimination sensor 19 and the like come in, and each signal whose waveform has been shaped is read by the CPU 30 from the input/output port 37.

The CPU 30 calculates the ignition timing and fuel injection amount based on the detection data of each sensor, and calculates the obtained ignition signal,
The fuel injection signal is transmitted from the output boats 38 and 39 to the igniters 16 and 16 through drive circuits 41 and 42, respectively. fuel injection valve 1
0 respectively.

Next, a control program for an embodiment of the apparatus of the present invention will be explained.

Figure 4 shows fuel injection tiIIIallIB for a four-cylinder engine.
70-chart of one embodiment of the principle is shown. This process is part of the main routine and is executed every few seconds.

In the same figure, ma(n (n is 1.2.3.4) l cylinder (#n
) also determines whether the fuel injection time (TAU) rg is the timing for calculating the fuel injection amount (step 50).

If it is not the TAU calculation timing for the n-th cylinder, the process is terminated, and if this is the timing, for example, the start signal is referred to to determine whether or not it is starting time (step 5).
1〉.

If it is starting, the fuel II allowance time for starting TAυSf
) is calculated in step 52). It is determined whether the first explosion detection flag FST#n of the n-th cylinder is vlw and the first explosion of the n-th cylinder is detected (step 53). If the first explosion has not been detected, the coefficient FT is determined with reference to the tables shown in FIGS. 5(A) and 5(B) (step 54).

Here, for a type of engine in which the air-fuel ratio is overrich at the time of starting, the table shown in Fig. 5 (A) is used, and here, the coefficient F
T gradually decreases. In addition, for an engine of the type in which the air-fuel ratio is over lean at the start of VJ, the table shown in Fig. 5 (B) is used.
After the cycle, the coefficient "T" gradually increases. After this, in step 53, the coefficient "T" is calculated as follows:
Step 55) Multiply TAtJsT by the above coefficient FT.
, this value is set to the temporary holding time #nTALJO of the n-th cylinder (step 56). In addition, if the first explosion is detected in step 53, the previous temporary hold 1 is detected in step 59.
fil#nT-AIJO fuel injection time when starting TAUS
Set to T and proceed to step 57. This is to set the starting injection time immediately before the first explosion when the first explosion is detected. In step 57, the value of the starting fuel injection time TAUST is set in the fuel injection signal TAU, and the process proceeds to step 58.

If it is determined in step 51 that the engine is not starting, the normal fuel injection time TAU is determined in step 60 and the process proceeds to step 58. In step 5B, TAt between fuel injection vf
J is set to the fuel injection time #nTAU for the n-th cylinder, and the process ends.

On the other hand, the first explosion detection flag for each cylinder is set in the process shown in FIG. The process shown in Fig. 6 is the bottom dead center of the gold cylinder (BD
C) Executed by an interrupt upon detection. Note that all first explosion detection flags FSr#n are reset to 707 at the start of engine startup.

In FIG. 6, first, the variable m (rr+ is 1.
2, 3.4> is set to "1" (Step 70), m
It is determined whether the number cylinder is at the bottom dead center of the explosion (step 71).

ml! If it is not cylinder explosion BDC, set the value of variable m to “1”
step 72), and returns to step 71 only when it is determined that the value of variable m is less than "5" (step 73), and ends the process when it is equal to or greater than "5".

As a result, after the value of the variable m matches the cylinder number that is the existing explosion bottom dead center, the process proceeds from step 71 to step 74.

In step 74, the rotation speed NST i from the previous bottom dead center interrupt to the current bottom dead center interrupt is calculated. After this,
Compare the rotational speed NST i obtained this time with the rotational speed NST i-1 obtained in the previous bottom dead center interrupt (step 75), and if the current rotational speed N5Ti is large, the current interrupt is generated. Since the torque is generated due to the explosion of the m-th cylinder, the first explosion detection flag F of the m-th cylinder is set in step 76.
Set v-1t in ST#m. Current rotation speed NS
When T i is small, this m-th cylinder has not exploded and is not generating torque, so the process ends without setting the first explosion detection flag FST#m.

Here, in a four-cylinder engine in which the air-fuel ratio becomes overrich at startup, the rotational speed NST changes as shown in Figure 7 <A), and at time t1, the first explosion of the No. 1 cylinder occurs as shown in Figure 7 (B). is detected, the first explosion detection flag FST#1 becomes vlv, and further, at time t2, the first explosion detection flag FST#3 of the No. 3 cylinder becomes 1v as shown in FIG. ．． Variable control of each TALJ #3 is not performed. After passing through the predetermined 111 rooms 1, Fig. 5 (
By referring to the table of A>, the coefficient FT gradually decreases and becomes 4.
Fuel injection time for cylinder 1 and cylinder 2 rAU#4゜d AL
As shown in FIGS. 7(D) and 7(E), I92 gradually decreases from overrich to a proper air-fuel ratio, and at time i3. First explosion detection flag FST#4 for each j+. FST#
2 each is 91? At that point, the fuel injection time TIJ
#4. The variable υ110 of each TAU #2 is stopped, and the starting of the gold cylinder is completed. After this, when the end of starting is detected by the start signal at time t5, there is no increase in the amount at starting.
Gold cylinder fuel injection time TALJ#1. TAU#3. T.A.
(J#4.TAtJ#2 is set to the normal fuel injection time at step 60 in FIG. 4. In this way, fuel fogging of the spark plug is prevented, and the engine is reliably started in the cylinder.

In addition, in a 4-cylinder engine whose air-fuel ratio is over lean when starting, the rotational speed NST is as shown in Figure 8 (A).
At time 1+, the first explosion of the No. 1 cylinder is detected and the first explosion detection flag FS #1 becomes 717 as shown in (B) of the same figure.
Then, at time t12, the first explosion detection flag FSr#3 is set as shown in FIG.
tK'3, TAU#1 during 1M of fuel injection after sono. TAU#3
No individual variable control is performed. To between predetermined J'Il1
After passing through, the coefficient F is determined by referring to the table in Figure 5 (B).
T gradually increases, and the fuel injection times TAU#4 and TAU#2 for the 4th and 2nd cylinders are shown in Fig. 8 (D) and (E), respectively.
As shown in , the air-fuel ratio gradually increases from over-lean to the proper air-fuel ratio, and the first explosion detection flag FST#4. FST#2 Husband'? becomes '1',
At that point, fuel injection time TAtJ#4. The variable control of each TAU#2 is stopped, and the starting of the gold cylinder is completed. After this, when the end of starting is detected by the start signal at the same time as aIlt, the amount increase at starting is stopped and the fuel injection time of the gold cylinder TAU#1. TAU#3. TALI4. TAU2 is the 4th
At step 60 in the figure, the normal fuel injection time is set.

In this way, the starting of the gold cylinder is reliably performed.

Note that even when controlling the fuel injection amount for each group by dividing it into a group of cylinders No. 1 and 3 and a group of cylinders No. 2 and 4, for example, in step 76 of FIG. When the first explosion of a cylinder or all cylinders is detected, the first explosion detection flag of that group is set to 717, so that it is possible to reliably start the golden cylinders in the same manner as in the above embodiment.

In the above-described embodiment, the first explosion may be detected by detecting whether the rotational speed (explosion stroke time) of each cylinder reaches, for example, 200 rpm. In addition, whether or not the current rotational speed has increased by 100rD11 or more from the rotational speed at # explosion, or whether the current cylinder rotational speed is higher than the explosion stroke rotational speed of the cylinder that exploded immediately before this cylinder. For example, it may be determined whether the rpm has increased by 50 rpm. Further, in order to determine whether the engine has completely exploded or started, the determination may be made based on whether or not the engine rotational speed has reached, for example, 4oorpm or higher.

[Effect of the invention] As described above, the fuel injection fJ at the time of starting of the ffi engine of the present invention
According to the 4-iI control device, variable control of the fuel am injection amount is performed only for cylinders that are not started, and the air-fuel ratio of the cylinder that has started or the group to which that cylinder belongs is maintained at an appropriate value, and the air-fuel ratio of the cylinder that has started is maintained at an appropriate value, and The air-fuel ratio of the cylinders that are not in use gradually approaches the appropriate value, and the starting of the cylinders is ensured, which is extremely useful in practice.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of the 8-position device of the present invention, Fig. 2 is a configuration diagram of an embodiment of a gasoline engine to which the device of the present invention is applied, Fig. 3 is a 70-step diagram of an electronic control circuit, Figs. Each figure shows a 70-diagram of the processing executed by the CPU, FIG. 5 shows a table of coefficients FT, and FIGS. 7 and 8 show the present invention'! FIG. 3 is a diagram for explaining the operation of the iA-go. Ml... Internal combustion engine, Ml... Operating state detection means, M
3... Calculating means, M4... First explosion detection means, M5...
- Fuel injection star variable stop means, 1... gasoline engine, 3... spark plug, 10... fuel injection valve, 16.
...Igniter, 30...CPLJ, 50-66...
・Suup.

Claims (1)

[Claims] In a starting fuel injection control device for an internal combustion engine, which controls the fuel injection amount for each cylinder or each group of cylinders of a multi-cylinder internal combustion engine, and variably controls the fuel injection amount at startup depending on the period from the start of the engine. , a first explosion detection means for detecting the first explosion for each cylinder, and variable control of the fuel injection amount at the time of startup of the cylinder in which the first explosion is detected by the first explosion detection means or the group to which the cylinder in which the first explosion is detected belongs. 1. A starting fuel injection control device for an internal combustion engine, comprising variable fuel injection amount stopping means for stopping the engine.