JPS59188043A - Fuel injection of internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the transition response performance of an engine by allowing the first injection of supporting fuel when engine acceleration is started and then allowing the intermittent injection of the supporting fuel in the acceleration over a prescribed value, added with the main injection carried-out in synchronization with the engine revolution. CONSTITUTION:During engine operation, an electronic controller 40 judges the formation of idle state from the output of a throttle sensor 29 and detects the moment of transition from idle state to off-idle state and carries-out auxiliary injection from a fuel injection valve 41. The variation of intke air amount DELTAQ/N per revolution of engine in unit time is calculated from each output of an air flow meter 2 and a crank angle sensor 32, and it is judged that DELTAQ/N is normal or not. In case of YES, namely in acceleration, it is judged that the variation is larger than a prescribed acceleration value B or not, and in case of YES, the value of asynchronous injection amount is read, and supporting fuel is jetted-out intermittently.

Description

[Detailed description of the invention] The present invention relates to a fuel injection method for an internal combustion engine.

In internal combustion engines, in addition to main injection (synchronous injection) in which fuel is injected into all cylinders of the engine simultaneously or in each cylinder group in synchronization with rotation, auxiliary injection (asynchronous injection) is performed in which auxiliary fuel is additionally injected. ing. This auxiliary injection is performed only once in response to a signal indicating the opening of the throttle valve, but since the required amount of fuel is injected at one time, during transient periods, the injection amount becomes excessive and the air-fuel mixture becomes excessive. When the mixture becomes rich and the throttle valve begins to open, auxiliary injection is performed regardless of the magnitude of acceleration, resulting in an excessive mixture. To deal with this, it is possible to prohibit Teisuke@ injection depending on the vehicle speed or the gear position of the transmission, but in this case, the auxiliary injection will not be performed in the necessary area while driving, in other words, the auxiliary injection area However, there are disadvantages in that the performance is limited, leading to deterioration of driving performance. On the other hand, it is possible to stop performing the auxiliary injection at the beginning of the opening of the throttle valve, and instead perform the auxiliary injection according to the magnitude of the throttle valve's temporal opening change as the magnitude of acceleration. The timing will be delayed and the acceleration response will not be sufficient.

The present invention proposes a fuel B injection method that does not have these drawbacks, in which auxiliary injection is performed once at the beginning of opening of the throttle valve, and then further auxiliary injection is performed when acceleration is determined to be greater than a predetermined value. Do this intermittently. In other words, during slow acceleration, auxiliary injection is performed only when the throttle valve begins to open, to prevent the mixture from becoming too rich, and during rapid acceleration, auxiliary injection is performed not only when the throttle valve begins to open. By performing this intermittently several times, it is possible to supply the amount of fuel necessary for acceleration and improve acceleration response. Moreover, by performing auxiliary injection intermittently over several times, the auxiliary fuel is distributed to several cylinders, preventing only a specific cylinder from receiving an overly rich mixture, and reducing unburned components in the exhaust gas. It also improves fuel efficiency.

In order to determine the magnitude of acceleration, it is possible to measure the amount of change over time in the amount of intake air per revolution of the engine, or the amount of change in the opening of the throttle valve per unit time. Although the auxiliary injection amount for the 11th injection is kept constant, it can be gradually decreased.

Note that the period of auxiliary fuel injection is set to a predetermined crank angle, for example, 3
It is best to set it to 0°.

The present invention will be described in detail with reference to the drawings.

In FIG. 1, air taken in from an air cleaner 1 passes through an intake passage 12 that includes an air flow meter 2 that measures the amount of intake air Q, a throttle valve 3, a surge tank 4, an intake boat 5, and an intake valve 6. It is sucked into the combustion chamber 8 of the main body 7.

The throttle valve 3 is connected to an accelerator pedal 13 in the driver's cab.

The combustion chamber 8 is defined by a cylinder head 9, a cylinder block 10 and a piston 11, and the exhaust gases produced by the combustion of the air-fuel mixture are discharged into the atmosphere via an exhaust valve 15, an exhaust port 16, an exhaust manifold 17 and an exhaust pipe 18. released to. The bypass passage 21 connects the upstream side of the throttle valve 3 and the surge tank 4, and the bypass flow control valve 22 controls the flow cross-sectional area of the bypass passage 21 to maintain a constant engine speed during idling.

An exhaust gas recirculation (EGR) passage 23 that guides exhaust gas to the intake system in order to suppress the generation of nitrogen oxides is connected to the exhaust manifold 1.
7 and surge tank 4, exhaust gas recirculation (EG
R) The control valve 24 responds to the electric pulse to open the EC and R passages 2.
Open and close 3. The intake temperature sensor 28 is the air flow meter 2
A throttle sensor 29 is installed inside the throttle valve 3 and includes a throttle switch that detects the intake air temperature and turns off when the throttle valve 3 opens from the fully closed position, and a potentiometer that changes in relation to the opening degree of the throttle valve 3. Detects opening degree and uses water temperature sensor 3
0 is attached to the cylinder block 10 to detect the cooling water temperature, that is, the engine temperature, and a well-known air-fuel ratio sensor 31 as an oxygen concentration sensor is attached to the collecting part of the exhaust manifold 17 to detect the oxygen concentration in the collecting part. , a crank angle sensor 3 that measures the engine speed N and discriminates cylinders.
2 detects the crank angle of the crankshaft from the rotation of the shaft 34 of the power distributor 33 connected to the crankshaft (not shown) of the engine body 7, and changes the crank angle (CA) by 360'' and 30°. The vehicle speed sensor 35 detects the rotational speed of the output shaft of the automatic transmission 36, that is, the vehicle speed.These sensors 2.28.29.3
The outputs of 0, 31, 32, 35 and the voltage of the storage battery 37 are sent to the electronic control unit 40. Fuel injection valves 41 for injecting fuel into each cylinder are respectively provided near intake ports 5 attached to the cylinders, and are supplied with fuel from a fuel tank 43 via a fuel passage 44 by a pump 42. The electronic control unit 40 calculates the fuel injection amount based on the control output signals from the sensors 2, 28 to 32+35, and sends an electric pulse having a width corresponding to the fuel injection amount to the fuel injection valve 41.

The electronic control device 40 includes a bypass flow control valve 22, an EGR
Control valve 24, solenoid valve 45 included in the hydraulic control circuit of the automatic transmission, and ignition coil 46 are controlled. The secondary side of the ignition coil 46 is connected to the power distributor 33. The charcoal canister 48 for preventing release of evaporated fuel 'B contains activated carbon 49 as an adsorbent, is connected to the fuel evaporation space of the fuel tank 43 via an adsorption passage 50, and is connected to the purge in the intake passage 12 via a separation passage 51. It is connected to the boat 52. The purge port 52 is located in the upper cylinder than the throttle valve 3 when the throttle valve 3 has a predetermined opening or less, and is located downstream of the throttle valve 3 when the throttle valve 3 is at a predetermined opening or more to control the intake g negative pressure. chosen to receive. The opening/closing valve 53 in the escape passage 51 includes a bimetal disc, and closes this passage 49 when the engine is at a low temperature below a predetermined temperature, thereby stopping fuel withdrawal to the intake system.

FIG. 2 shows details of the electronic control unit 40, including a central processing unit (CPU) 56 consisting of a microprocessor, a read-only memory (ROM) 57, and a constant speed access memory (RA).
M) 58, analog/digital converter (A/D) 60 with multiplexer and human output device with buffer ff1 (
ilo) 61 are connected to each other via a bus 62. an air flow meter 2 that generates an analog output signal;
Intake temperature sensor 28, water temperature sensor 30, air-fuel ratio sensor 31
And the output of storage battery 37 is sent to A/D 60. Also, a throttle sensor 29 that generates a digital output signal.
and is sent to the output cover I1061 of the crank angle sensor 32, and the bypass flow control valve 22, EGR control valve 24, fuel injection valve 41, solenoid valve 45 and ignition coil 46 receive the control output signal of the CPLI 56 via Ilo 61. receive.

Main injection, which injects fuel to all cylinders simultaneously or for each cylinder group in synchronization with engine rotation, is well known, so auxiliary injection, which is performed additionally, will be explained below.

First, the main routine program for calculating the injection conditions and injection amount for auxiliary injection will be explained with reference to FIG. 3. In step 101+g, the main routine program for auxiliary injection is started. In step 102,
It is determined from the output signal of the throttle sensor 29 whether the throttle valve 3 is closed (idle), and if it is idle, the previous idle determination flag is set in step 103. If it is not idling, it is determined in step 104 whether it was idling last time, and if it was idling last time, in step 105, the auxiliary injection amount is set to a warm-up acceleration increase value that is a function of water temperature, and the RAM is stored.
58. Then, the process proceeds to step 106, where the auxiliary firing execution flag is set, and the previous idle determination flag is reset (step 107).If the previous idle determination flag was not present, the process proceeds from step 106 to step 107. In this way, the moment when the throttle valve 3 starts to open from fully closed, that is, the moment when it transitions from idle to off-idle, is detected,
Execute one auxiliary injection.

Next, in step 108, the calculation timing of the intake air amount change ΔQ/N per engine revolution within a unit time is determined. This calculation timing is obtained by setting a flag every several to tens of m5ec using a timer interrupt.

If the calculation timing does not match, the auxiliary injection program is terminated, but if the calculation timing matches, the process proceeds to step 109, resets the ΔQ/N calculation timing flag, and changes the operating parameters read into the RAM 58, i.e. The output Q of the air flow meter and the output N of the crank angle sensor are read into the CPU 56 (step 110), and 80/N, that is, the current Q/N and the previous Q/N are read into the CPU 56 (step 110).
The difference between the current Q/N and the average value of the previous Q/N is calculated (step 111). Step 11
In step 2, determine whether ΔQ/N is positive, that is, whether the current Q/N is larger than the previous or previous average Q/N, and therefore whether it is acceleration. If so, the process proceeds to step 113, and if ΔQ/N is negative, it means deceleration, and there is no need for auxiliary injection, so the auxiliary injection program is ended. In step 113, it is determined whether this ΔQ/N is larger than a predetermined acceleration value B that requires an additional auxiliary injection amount. This predetermined acceleration value B may be constant, but it changes depending on the engine temperature, and when the engine temperature is low, warming up can be promoted by reducing the predetermined value B. Now, if ΔQ'/N is smaller than B, the auxiliary injection program is terminated as there is no need for auxiliary injection, but if ΔQ/N is larger than B, the process proceeds to step 114 and the value C of the asynchronous @force is stored in the RAM 58.
Load into. This value C may be the warm-up acceleration increase value A described above, but it may also be a function of ΔQ/N and A.

Now, there is a possibility that the auxiliary injection becomes excessive and the mixture supplied to a specific cylinder becomes too rich, so during the auxiliary injection execution anvil cycle (E'CA), 80/N is less than 8. Even if it becomes large, it is better to prevent the mixture from becoming too rich by reducing the injection amount. For this reason, step l14
In step +15 following, it is determined whether the flag after execution of the auxiliary injection is masked. If it is masked, the Ikusuke injection target is decreased from the value C in step 116, and the process proceeds to step 119 to execute the auxiliary injection. Set the flag (step 119) and terminate the program (
Step I20). On the other hand, if the mask of the flag after execution of auxiliary embroidery has been released, the mask flag after execution of auxiliary embroidery is set (step 117), the value E of the reduction period is set in the mask counter, and the process proceeds to step 119.

Figure 4 is a &1 diagram for explaining auxiliary injection during racing. When the throttle valve is opened from fully closed (opening degree 0%), the throttle switch in the throttle sensor is turned on, and the auxiliary injection LS is activated once. It is done. When ΔQ/N increases with the engine speed N and exceeds a predetermined acceleration value B, the auxiliary injection flag is turned on continuously at intervals of 30° CA, for example, to perform continuous auxiliary injection. Also shown here is the main injection pulse, which is simultaneously applied to all cylinders in synchronization with the engine speed.

The width of all auxiliary injection pulses may be the same, but as shown in Figure 5, the width of the auxiliary pulse when the throttle valve starts to open should be larger than the width of the subsequent auxiliary injection pulse, in other words, It is also possible to reduce or reduce the amount of auxiliary injection.

The temporal variation ΔTH of the opening degree TH of the throttle valve 3 can also be used instead of 〇/H for the temporal variation of Q/H. FIG. 6 shows the program, and only shows steps 108' to 113' that are different from those in FIG.
It corresponds to i.e. 108', 109', 111
', 112' and 113', ΔTH is used instead of 80, /N, and in step 110, i31 [1'I instead of Q and H as parameters] is read.

Since the timing of the auxiliary injection is determined by the crank angle, its execution is performed in the crank angle interrupt routine as shown in FIG.

In step 20+, dividing is started. Since the main injection is performed near the piston top dead center of the powder cylinder, it is determined whether the injection timing is correct, and if the injection timing is correct, the 1-time injection amount is read into the RAM 58 (step 2o3). As is well known, this main injection amount is the sum of the basic injection quantity calculated from Q/N and an increase value according to the operating parameters.

If the injection timing is not reached, it is determined in step 204 whether or not the auxiliary injection execution flag is set;
If it has been set, the process proceeds to step 205, where the value of the auxiliary injection type is set in the RAM 58, and the auxiliary injection execution flag is reset (step 206).

As explained with reference to FIG. 3, the amount of auxiliary injection is reduced during the auxiliary injection execution anvil cycle (E'CA), so it is necessary to measure this mask period. Therefore, after steps 203 and 206, and when the auxiliary injection flag is not set, it is determined in step 207 whether or not the flag after the auxiliary injection is masked, and if it is masked, the flag is counted from the mask counter. Subtract by 1 (step 208). In step 209, it is determined whether or not the mask period has ended and the mask counter has reached O. If it has become 0, the process proceeds to step 210 to reset the mask counter after the execution of the auxiliary injection, and then executes the injection (step 2 ]1) L/ to end this interrupt routine (step 212). When the flag after execution of auxiliary injection is not masked and when the mask counter is not 0, the process goes to step 211 to execute injection.

In this way, according to the present invention, since additional auxiliary fuel is injected in accordance with acceleration, the engine speed increases quickly,
The generated 1-lux of the engine increases and the transient response of the engine improves. This improvement in responsiveness makes it possible to reduce the amount of main injection, which has the advantage of improving fuel efficiency and reducing the amount of unburned components in the exhaust gas.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of an internal combustion engine to which the present invention is applied, Fig. 2 is a block diagram of its control device, Fig. 3 is a flowchart of a program for calculating the injection conditions and amount of auxiliary fuel, and Figs. FIG. 5 is a diagram explaining the operation, FIG. 6 is a flowchart of a part of the program that is partially modified from FIG. 3, and FIG. 7 is a flowchart of the injection execution program. 2... Air flow meter, 3... Throttle valve, 8...
Cylinder, 29... Throttle sensor, 32... Crank angle sensor, 40... Electronic control device.

Claims (1)

[Claims] 1. In addition to injecting fuel into the cylinders of an internal combustion engine in synchronization with engine rotation, auxiliary fuel is first injected once at the start of engine braking acceleration, and then auxiliary fuel is injected intermittently when acceleration exceeds a predetermined value. A fuel injection method for an internal combustion engine, characterized by injecting fuel. 2. The method according to claim 1, characterized in that the magnitude of acceleration is determined based on the amount of change per unit time in the amount of intake air per revolution of the engine. 3. Claim 1, characterized in that the magnitude of acceleration is determined based on the amount of change in opening degree of the throttle valve per unit time.
The method described in section. 4. The method according to claim 1, characterized in that the injection amount of the auxiliary fuel intermittently injected at one time is constant. 5. The method according to claim 1, characterized in that the injection amount of the intermittently injected auxiliary fuel is reduced from the second time onwards. 6. The method according to claim 1, characterized in that the period of the auxiliary fuel injection is made to correspond to a predetermined crank angle.