JPS6019929A - Electronically controlled fuel injection device - Google Patents

Abstract

PURPOSE:To gradually increase an engine torque and prevent a large shock, by gradually returning an engine control to a feedback control when a partial lean condition is unestablished owing to any factors other than acceleration and deceleration during execution of a partial lean control. CONSTITUTION:A voltage of a battery 24 and detection signals of an intake air temperature sensor 25 and an air flow meter 26 are supplied to an A/D converter 16 in an electronically controlled fuel injection device 10. On the other hand, an output from a crank angle sensor in a distributor 19 and detection signals of a throttle position sensor 20, O2 sensor 21, starter 22 and vehicular speed sensor 23 are supplied to an input interface 13. CPU11 decides whether or not a feedback control condition is established according to the output signals from the above-mentioned various sensors. If the O2 sensor 21 is inactive or a vehicle is running under high load or with no supply of fuel, a feedback control is not carried out for purposes of securing of operability and safety, and a fuel injection amount is set to be a basic injection amount by making an air-fuel ratio correction coefficient as 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an electronically controlled fuel injection system, and in particular to feedbank control that settles the actual air-fuel ratio to near the stoichiometric air-fuel ratio, and that controls the actual air-fuel ratio to be thinner than the stoichiometric air-fuel ratio. This invention relates to an improvement of the electronic side 1311 fuel injection device, which uses partial lean control (lean state) depending on the situation.

BACKGROUND OF THE INVENTION In a conventional electronically controlled fuel injection system, under certain conditions, the signal from the 02 sensor determines whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio2, and if it is richer, the fuel injection amount is reduced. If it is too thin, so-called feedback control is performed so that the amount is increased so that the actual air-fuel ratio matches around the stoichiometric air-fuel ratio. In addition, in order to achieve low fuel consumption, when the engine is in a stable state under low load, for example when the following conditions are met, the above feed hack control is turned off and the actual engine speed is reduced. It is known to perform so-called partial lean control in which the fuel ratio is made higher than the stoichiometric air-fuel ratio.

1, 70 ff 'C≦Water temperature≦100°C2, Throttle opening≦40°3.2°/40m5>Throttle opening change rate (for sudden acceleration judgment) 4.2°/400 mS>Throttle opening change rate (For determining slow acceleration) 5. Speed≧40Km/h 6. Feedbank conditions are met Figure 1 shows the operation of a conventional electronically controlled fuel injection system that performs such feedbank control and partial lean control. It is a flowchart. As shown in the figure, when the O2 sensor is not activated, when driving under high load, when fuel is cut, etc., feedback control is not performed to ensure drivability and safety, and the air-fuel ratio correction coefficient FAP is set to 1. Toshiki Sl, S
2), the fuel injection amount TAU (which is calculated by multiplying the basic injection amount TP by the air-fuel ratio correction coefficient PAF) becomes the basic injection amount TP (S3). If the feed bank control condition is satisfied, it is determined whether the partial lean condition is satisfied or not (S4), and if there is a transition from partial lean control P/L to feed bank control F/B, FAF is set to 1.0. As a result, the system immediately shifts to feed bank control (S4a,
54b) Then, feedback control in steps 85 to S7 is performed. That is, when it is determined from the output of the 02 sensor that the actual air-fuel ratio A/F is in a rich state (a state in which the air-fuel ratio is smaller than the stoichiometric air-fuel ratio is −5), the air-fuel ratio correction coefficient FAF is changed to FAF −K , ( K is a constant) (S6), the actual air-fuel ratio is increased, and the actual air-fuel ratio A/F is lean! When it is determined that the air-fuel ratio is +3 (meaning a state in which the air-fuel ratio is larger than the stoichiometric air-fuel ratio), the air-fuel ratio correction coefficient FAI? By setting FAF +K 2 (K 2 is a constant) (S7), the actual air-fuel ratio is decreased.

FIG. 2 is a diagram showing the relationship between the state of the air-fuel ratio A/F and the state of change of the air-fuel ratio correction coefficient FAF. When the air-fuel ratio A/F becomes rich, the air-fuel ratio correction coefficient PAF becomes a constant of 2. When the air-fuel ratio A/F becomes lean, the air-fuel ratio correction coefficient FAF becomes a constant and increases with a slope determined by the magnitude.

Furthermore, when the partial lean condition is satisfied (S4), the air-fuel ratio correction coefficient FAF is changed to A (a value smaller than 1.0 indicates the degree of lean combustion), and as a result, combustion occurs at an air-fuel ratio greater than the stoichiometric air-fuel ratio. This lean combustion continues until the partial lean condition no longer holds true. For example, when fuel injection is 1 TAU - basic injection amount TP, A/
If F = 14.5 (stoichiometric air-fuel ratio), A = 0.8
Then, fuel injection amount TAU - basic injection amount TPX air-fuel ratio correction coefficient FAF - basic injection amount TPX 0.8, the fuel injection amount decreases by 20%, and A/F = 18.1
becomes. Therefore, the A/F becomes high, resulting in a lean burn state.

Problems with the Prior Art Incidentally, in the conventional electronically controlled fuel injection system of this type, when the partial lean condition no longer holds, the feedback control state is immediately returned to the state, but at this time, relatively large shocks and shocks are caused to the vehicle. There were some problems that arose.

OBJECTS OF THE INVENTION The present invention solves these conventional problems and aims to smoothly transition from a partial lean control state to a feeder control state.

Structure of the Invention The reason why a large shock occurs when returning to the feedback control state as described above is thought to be due to the following reasons. In other words, while partial lean control is being executed, the engine is in a lean burn state, so the engine's 1-lux is lower;
This is because the torque increases when returning to the feed pack control state, so in the conventional method of immediately returning from the partial lean control state to the feed pack control state, a sudden change in torque occurs during the transition. Therefore, in the present invention, in order to avoid this, the return speed is changed depending on the engine condition when returning from partial lean control. In an electronically controlled fuel injection system that performs air-fuel ratio control and partial lean control that controls the air-fuel ratio to a value greater than the stoichiometric air-fuel ratio, if the partial lean condition no longer holds true due to acceleration/deceleration, partial lean control is performed. The electronically controlled fuel injection system is configured to immediately return to feed hassock control, and to gradually return from partial lean control to feedback control when the partial lean condition is no longer satisfied due to factors other than acceleration/deceleration. Therefore, if the partial lean condition is not satisfied due to factors other than acceleration/deceleration during execution of partial lean control, the feedbank control is gradually returned to, so the engine torque is gradually increased, and thus The shock that I experienced is unlikely to occur.

Embodiment of the Invention FIG. 3 is a block diagram of essential parts showing an example of the hardware configuration of an electronically controlled fuel injection device of the present invention.

In the same figure, IO is the control section of the electronically controlled fuel injection system, and the microcomputer 1 and its bus 1
An input interface circuit 13.2 connected to the microcomputer 11 via the input interface circuit 13.2. R for storing programs etc.
OM14. RAM 15 for temporarily storing calculation results, etc. AD converter 16 that converts analog signals into digital signals.
It consists of an output interface circuit 17 and a constant voltage power supply 18. The input interface circuit 13 includes an output signal from a crank angle sensor provided in the distributor 19 that detects the crank reference position, rotation angle, and cylinder position, and an output signal from a throttle opening sensor 20 that detects idling and high load conditions. The signal, the output signal of the 02 sensor 21 that detects the oxygen concentration in the exhaust pipe, the output signal of the starter 22 that detects when the engine is starting, and the output signal of the vehicle speed sensor 23 that detects the current vehicle speed are added to the AD converter 16. , the output voltage of the battery 24, the output signal of the intake temperature sensor 25 that detects the intake air temperature, and the output signal of the air flow meter 26 that detects the amount of intake air are added. Also,
The output of the output interface circuit 17 is the injector 2
7 is connected.

FIG. 4 is a flowchart showing an example of a software configuration for realizing the electronically controlled fuel injection function of the present invention. As shown in the figure, the microcomputer 11 first identifies whether or not the feed bank control conditions are satisfied based on the output signals of various sensors (310), as in the conventional case.
, when the 02 sensor is not activated, when driving under high load, when fuel is cut, etc., feed bank control is not performed to ensure drivability and safety, and the air-fuel ratio correction coefficient FA is
F is set to 1 (511), and the fuel injection amount TAU is set to the basic injection amount TP (S13). At this time, the flag FLA
G is set (S12). This flag FLAG indicates the execution state of partial lean control, the flag set (FLAG 5ET) indicates the state in which feed bank control can be executed, and the flag clear (FLAG CLEAR
) indicates that partial lean control is being executed or that partial lean control is transitioning to feed hack control.

If the feed bank control condition is satisfied, it is determined whether the flag is set (step 314), and if the flag is set, then feed bank control is in progress, so step 315)
~Implement SI7 feedback control. That is, as in the past, the actual air-fuel ratio A/F is determined from the output of the 02 sensor 21.
is determined to be in a rich state, the air-fuel ratio correction coefficient PA
By setting P to FAF- (SI6), the actual air-fuel ratio is increased, and when it is determined that the actual air-fuel ratio A/F is in a lean state, the air-fuel ratio correction coefficient F'AP is changed to FAF.
By adding 2 to + (317), the actual air-fuel ratio is reduced.

If the flag is cleared, it means that partial lean control is being executed or transitioning to feedback control, so first the microcomputer 1 determines whether it is currently accelerating or decelerating (31B), and if it is accelerating or decelerating, it corrects the air-fuel ratio. Coefficient FAI? is set to 1.0 (319), the air-fuel ratio is immediately reduced to the stoichiometric air-fuel ratio, and the flag is set at the same time (320).

If it is determined in step 318 that the acceleration/deceleration is not in progress,
The microcomputer 11 determines whether the partial lean control condition is satisfied based on the output signals of various sensors (S21). If the partial lean condition is established, the air-fuel ratio correction coefficient FAIi is larger than A. The value obtained by subtracting K. (K. is a constant) from the air-fuel ratio correction coefficient PAF is set as the missing air-fuel ratio correction coefficient F.S22.523
), if the air-fuel ratio correction coefficient 17 is smaller than 8, this is
(S24). Also, clear the flag to indicate that partial lean control is being executed (
S25>.

Further, if the partial lean condition is not satisfied, the microcomputer 11 determines whether the air-fuel ratio correction coefficient FAF is 1.0 or more (326), and if it is 1.0 or more, the process moves to step S19 and the air-fuel ratio correction coefficient FAF is determined to be 1.0 or more. The fuel ratio correction coefficient FAF is set to 1.0, a flag is set, the partial lean control is ended, and the air-fuel ratio correction coefficient F/i F is set to 1.
．． If it is smaller than 0, the coefficient K is added to the air-fuel ratio correction coefficient PAP.
・The value obtained by adding 27 is the air-fuel ratio correction coefficient FAF (3
27).

Figure 5 shows the state of G to flag FL and the air-fuel ratio correction coefficient FA.
FIG. 3 is a diagram showing an example of temporal changes in the magnitude of F and the air-fuel ratio A/F. Time during feedback control execution 1. When the partial lean condition is established, the flag FLAG is cleared as shown in the figure, and the air-fuel ratio correction coefficient FAF gradually decreases at a rate determined by the coefficient, and accordingly, the air-fuel ratio A/F becomes the stoichiometric air-fuel ratio. When the air-fuel ratio correction coefficient FAF reaches the value A, a lean burn state is reached. At time t2, when the partial lean condition is no longer satisfied due to factors other than acceleration/deceleration, such as the water temperature falling below a predetermined temperature, the air-fuel ratio correction coefficient FAF gradually increases at an increase rate determined by the coefficient 3, and accordingly. The air-fuel ratio A/F also gradually decreases toward the stoichiometric air-fuel ratio. Then, when the air-fuel ratio correction coefficient FAF reaches 1.0, the flag FLAG is set and feed bank control is executed. Moreover, when the partial lean condition is satisfied again at time t3,
Partial lean control is executed as before. If the partial lean condition is not satisfied due to acceleration or deceleration being performed at time t4 during execution of this partial lean control, flags F1 and AG are set and the air-fuel ratio correction coefficient FAF is set to 1.0. and feed bank control is started at low 1.

In the above embodiment, the return speed Ko to feedbank control can be changed depending on the type of engine and the type of engine.

FIG. 6 is a flowchart showing another example of the software configuration for realizing the electronically controlled fuel injection function of the present invention;
30 to S42 indicate each step. In this embodiment, if the feedback condition is not satisfied (533), it is determined whether or not the current acceleration/deceleration is being performed. 338. Shift to Tsuk control. 339
If partial lean control is in progress, the steps S13 to S15 in FIG. When the <-charlene condition is not satisfied, the process moves to step-knob (S40) and performs foot-knob control (334). According to this configuration, when the partial lean condition is not satisfied due to factors other than acceleration/deceleration, the transition speed to feedback control is as follows:
Since the coefficient used for feedback control is determined by 2, the return speed cannot be changed as in the embodiment of FIG. 4, but the configuration is simpler than that of FIG. 4.

As described in detail, according to the present invention, when the partial lean condition is not satisfied due to factors other than acceleration/deceleration during i-Charlean control, the feedback control is gradually returned to. Since L' is larger, the engine torque is gradually increased, so that the conventional large shock does not occur. Further, when the partial lean condition is no longer satisfied due to acceleration/deceleration, the feedback control is immediately returned to, so that acceleration/deceleration performance is not deteriorated.

[Brief explanation of the drawing]

Fig. 1 is an operation flowchart of a conventional electronically controlled fuel injection system that performs feed hack control and partial lean control, and Fig. 2 shows the state of the air-fuel ratio A/F and the air-fuel ratio correction coefficient F.
A line diagram showing the relationship with the changing state of AF, FIG. 3 is a block diagram of a main part showing an example of the hardware configuration of the electronically controlled fuel injection device of the present invention, and FIG. 4 is a diagram showing the electronically controlled fuel injection function of the present invention. Flowchart 1-1 showing an example of the software configuration to be realized; FIG. FIG. 6 is a flowchart showing another example of the software configuration for realizing the electronically controlled fuel injection function of the present invention. 10 is a control unit of an electronically controlled fuel injection device, 19
is a distribuke with a built-in crank angle sensor, 2
0 is a throttle opening sensor, 2I is a 02 sensor, and 23 is a vehicle speed sensor. Patent applicant Fujitsu Ten Co., Ltd. Representative patent attorney Tamamushi Gobu and one other person

Claims (1)

[Claims] In an electronically controlled fuel injection system that performs feedback control that controls the air-fuel ratio using the stoichiometric air-fuel ratio as a target value and partial lean control that controls the air-fuel ratio to a value greater than the stoichiometric air-fuel ratio, partial lean is caused by acceleration and deceleration. When the conditions no longer hold, partial lean control immediately returns to feed puncture control, and when partial lean conditions no longer hold due to factors other than acceleration/deceleration, partial lean control returns to feedback control after 1 minute. An electronically controlled fuel injection device characterized in that it is configured to: