JPS60195350A - Fuel supply control device in internal-combustion engine - Google Patents

Abstract

PURPOSE:To sufficiently exhibit the cooling effect of intake-air to practically improve the distribution of air-fuel ratio among engine cylinders, accordingly, so that the output performance of an engine is enhanced, by making the ratio of fuel injection of main and auxiliary injection valves variable in accordance with the rotational speed of the engine. CONSTITUTION:An optimum fuel injection rate alpha of an auxiliary injection valve is beforehand obtained from a two-dimensional map which is based upon the relationship between the load of an engine, such as, for example, the amount of intake-air, and the rotational speed Ne of the engine, as shown in the drawing, in accordance with the relationship among the injection rate alpha of the auxiliary injection valve (=injection amount of auxiliary injection valve/(fuel injection amount of auxiliary injection valve + fuel injection amount of main fuel injection valve), output torque Ti, variations in output torque Ti, emission HC, CO, NOX and the distribution of air-fuel ratio DELTAA/F, and the cooling effect of intake-air may be satisfactorily exhibited. Accordingly, the amount (q) of fuel injection is computed in accordance with predetermined operating condition parameters of the engine, and therefore, a fuel injection amount of q(1-alpha), where is obtained as mentioned above, of fuel is injected from a main fuel injection amount, and as well a fuel injection amount qalpha of fuel is injected from the auxiliary fuel injection valve.

Description

Description: TECHNICAL FIELD The present invention relates to a fuel supply control device for an internal combustion engine which is provided with an auxiliary fuel injection valve for cooling intake air.

Prior Art In addition to the main fuel injection valve (simply referred to as the main injection valve) provided for each cylinder, there is a fuel injection valve upstream of the intake pipe, such as a surge tank or throttle. Internal combustion engines are already known in which an auxiliary fuel injection valve (simply referred to as an auxiliary injection valve) is provided near the fuel injection valve. The fuel injection from the sub-injector cools the intake air, improving the filling efficiency and, therefore, improving the output performance. As shown in Figure 1, Kz'! When the large air temperature THA becomes lower, the intake air amount J1cm increases, and therefore the output torque T1 also increases. By the way, when the intake air temperature THA is lowered from 50℃ to 20℃, the intake air amount Ga and the output torque Tl will be 50-20/273+5.
0 Medium 'J% improvement.

FIG. 2 shows the air-fuel ratio A/F vs. output torque Ti ratio characteristic.

As shown in FIG. 2, the output torque Ti with respect to the air-fuel ratio A/F peaks at a certain point (referred to as 11: output air-fuel ratio), and beyond this peak, the output torque T1 becomes low whether the engine is rich or lean. Also, when the intake temperature becomes low, the first
As explained in the figure, the output torque Tl increases. For example, when the intake temperature decreases from THAH to THAL, the TI at the output air-fuel ratio increases from bl to bl, increasing by ΔT1.

However, if the distribution deteriorates, for example, in a 4-cylinder engine, the average air-fuel ratio is adjusted to the output air-fuel ratio 1, but in this case, the air-fuel ratio A/F of 2 cylinders becomes a2, and the air-fuel ratio A/F of the remaining 2 cylinders becomes If /F is set to a3 and the distribution is deteriorated by ΔA/F, the torque at that time will be equal to the average torque bsL of the torque for air-fuel ratio A/F of 712 and 83. In the end, even if you aim to improve output performance by lowering the intake air temperature THA, if the distribution deteriorates, the ΔT
It only improves by 2 minutes. If the distribution deteriorates further, the output torque Ti will be lower, and on the contrary, the output torque Ti will be higher if the fuel is not injected from the sub-injector.
There is a case.

When the distribution deteriorates as described above, there is a problem in that the output torque Ti cannot be sufficiently improved no matter how much the intake air is cooled by the fuel injection of the sub-injector and the intake air weight Ga increases.

Purpose of the Invention In view of the above-mentioned problems of the conventional type, an object of the present invention is to make the main injection valve, sub-injection valve, and injection ratio variable depending on the load and rotation speed, thereby reducing emissions caused by poor distribution, for example. By reducing the injection ratio by the sub-injection valve at light loads and low rotations where the deterioration of drivability is noticeable, and by increasing the above injection ratio at high loads and high rotations where various performances are less likely to deteriorate due to deterioration of distribution, the intake air The objective is to sufficiently exhibit the cooling effect, thereby substantially improving the air-fuel ratio distribution and improving output performance.

DESCRIPTION OF THE INVENTION The structure of the present invention which achieves the above objects is shown in FIG. That is, in an internal combustion engine that includes a main fuel injector provided for each cylinder and an auxiliary fuel injector commonly provided for each cylinder in the upstream portion of the intake passage, the fuel injection amount calculation means calculates the amount of fuel to be calculated based on the predetermined operating state of the engine.・Calculate the fuel injection amount q according to the f parameter. On the other hand, the load detection means detects the load of the mining engine, the rotational speed detection means detects the rotational speed of the engine,
The injection ratio calculation means calculates the injection ratio α between the main fuel injection valve and the auxiliary fuel injection valve according to the detected load and rotational speed. The main fuel injection amount calculating means calculates the fuel injection amount q to υ main fuel injection amount q(1-α) according to the calculated injection ratio,
The auxiliary fuel injection amount calculation means calculates the auxiliary fuel injection amount qα by the fuel injection amount q according to the calculated injection ratio α. The main fuel injection execution means injects the main fuel injection amount q(1-α) from the main fuel injection valve, and the auxiliary fuel injection execution means injects the auxiliary fuel injection amount qα from the auxiliary fuel injection valve. be.

Example The present invention will be explained in detail with reference to the drawings from FIG. 4 onwards.

First, the principle of the present invention, the reason why it is more reasonable to make the injection ratio variable, will be explained with reference to FIG.

In Fig. 4, the horizontal axis shows the injection ratio α of the auxiliary injector (the injection amount of the auxiliary injection valve/(the injection amount of the main injection valve + the auxiliary injection valve 9)), and the vertical axis shows the torque TI, torque fluctuation ΔTis Emissive items such as HC, Co, NOx.

The air-fuel ratio distribution ΔA/F is shown. Further, the solid line shows the characteristics in the high load high speed range, and the broken line shows the characteristics in the light load low speed range. In a light load and low rotation range, the intake air flow rate is low, so the fuel injected from the sub-injector is difficult to atomize, and a large proportion of the fuel adheres to the inner wall of the intake pipe. On the other hand, in a high-load, high-speed range, the intake air flow rate is high, so the fuel is easily atomized and the amount of adhering fuel is reduced. Therefore, when the injection ratio α is gradually increased,
The tendency for distribution deterioration is smaller at high loads and high rotations, and as a result,
The deterioration tendency of emission (special KCO) and torque fluctuation JT becomes smaller, and the injection ratio at which torque Tl becomes maximum also becomes higher. The optimal injection ratio is difficult to determine from the light load and low rotation range where emissions and drivability become a problem, and from the emissions and torque fluctuations, it is determined at the α1 point or α2 point in the figure.
On the other hand, it can be seen that in the high-load, high-speed range, the optimum injection ratio should be set at the point where the torque is maximum (point α3 in the figure).

In the present invention, as shown in FIG. 5, the optimum injection ratio α is prepared in advance as a two-dimensional map based on one load, for example, intake air tLQ and rotational speed N6, and by using this map, it is possible to obtain a sufficient intake air cooling effect. If I can do my best, I will be K.

FIG. 6 is an overall schematic diagram showing an embodiment of a fuel supply control device for an internal combustion engine according to the present invention. In Figure 6, 4
A cylinder engine is assumed. That is, main injection valves 3-1 (3-2, 3-3,
3-4) is provided. Further, a sub-injection valve 5 is provided in, for example, a suction tank 4 of the collective intake pipe. However, the sub-injection valve 5 is common to each cylinder. 6 is air 70-
A meter that directly measures the amount of intake air and generates an analog voltage electrical signal proportional to the amount of intake air.

The rist repeater 7 is provided with two rotation angle sensors 8.9 which generate an angular position signal every time the shaft rotates, for example, 720' or 300 revolutions in terms of crank angle.

The control circuit IO includes air flow meter 6 and rotation angle sensor? 8
, 9 to the main injection valves 3-1 to 3-4. It controls the sub-injection valve 5, and is composed of, for example, a microconbeater.

FIG. 7 is a detailed block circuit diagram of the control circuit IO of FIG. 6. In FIG. 7, the analog signal of the air 70-meter 6 is sent to the ADD converter 1
02.

Each pulse signal from the rotation angle sensors 8 and 9 is supplied to a timing generation circuit 103 for generating an interrupt request signal and a reference timing signal.

Further, the base pulse signal of the rotation angle sensor 9 is supplied to a predetermined position of the input interface 105 via the rotation speed forming circuit 104. The rotation speed forming circuit 104 has a rotation speed of 30°.
It consists of a dart that is controlled to open and close for each CA, and a counter that counts the number of pulses of the clock signal CLK of the clock signal generation circuit 106 that passes through this dart.
Two signals are formed that are inversely proportional to the rotational speed of one engine.

ROM 109G'l:N Programs such as a main routine and an interrupt routine to be described later, and various fixed data and constants necessary for these processes are stored in advance.

Latch circuit l1l-1% down counter 112-11
Free lag flop 113-1. and drive circuit 114
-1 is provided for the main injection valves 3-1 to 3-4, including a latch circuit 111-2, a down counter 112-2, a free,
The log frog 113-2 and the drive circuit 114-2 are provided for the sub-injection valve 5. For example, when the injection amount data T of the sub-injection valve 5 is calculated, this data T is sent to the latch circuit 111-
Set to 2. Next, when the injection start signal (strobe signal) S2 is generated at the injection start timing after a predetermined time, the data of the latch circuit 111-2 is reset to the down counter 112-2, and at the same time, the free lag flop 113-2 is reset. Set. As a result, the drive circuit 114-2 operates and the sub-injection valve 5 is energized. During this time, the down counter 112-2 performs clock counting, and finally the carrier terminal of the down counter 112-2 is
When it reaches the '1'' level, the differential flof flL3-2 is reset and the drive circuit 113-2 stops energizing the sub-injector 5.Tsumarily, the sub-injector 5 is energized for the above-mentioned fuel injection time T. Therefore, an amount of additional fuel corresponding to the fuel injection time is sent to the combustion chamber of the engine body l.

Referring to the flowchart in FIG. 8, the control circuit l in FIG.
The operation of O will be explained. In FIG. 8, step 801
starts at every predetermined crank angle, for example 180° CA, and proceeds to Stella F802, where the air flow meter 6
From the intake air amount data Q and rotational speed forming circuit 104
Take in the rotational speed data N, 3 from. In step 803, the data Q.

Basic injection ftq, , is calculated using a two-dimensional mag (not shown) based on No., and then a correction calculation is performed using necessary operating state parameters to calculate the fuel injection amount q. Note that this fuel injection amount q indicates the total amount of fuel injected from the main injection valves 3-1 to 3-4 and the sub-injection valve 5.

In step 804, the optimum injection ratio α is calculated using the two-dimensional map shown in FIG. 5 based on the data Q and Ne.

In step 805, the injection time τ□ of the main injection valves 3-1 to 3-4 is calculated as τ□←q(1-α), and in step 7'806, this Tm is sent to the latch circuit 111-1. set.

In step 807, the injection time τ8 of the main injection valves 3-1 to 3-4 is calculated as τ8←qα, and the stellar f808 sets this τB in the latch circuit 111-2.

This routine then ends at Stella 7°809.

In this way, τ1. τ8 is the latch circuit 111-1°11
1-2, the latch circuit 11 is activated by the injection start signal SL+82 generated at a predetermined timing.
1-1. l1l-2's 7"-Yu is down counter 112
-1, 112-2 and injection will be executed. Note that it is more advantageous in terms of the distribution ratio to control the injection start signal S2 so that it is generated when the intake air flow velocity near the sub-injector is high. Also, normally, the injection start signal S.

occurs not every 180° CA but every 360'CA, and the main injection valves 3-1 to 3-4 inject simultaneously.

In the above-described embodiment, the amount of intake air is used as the load, but it goes without saying that intake air pressure, throttle valve opening, etc. may also be used.

As described in detail, according to the present invention, since the ratio of injection by the main injection valve and injection by the sub-injection valve is made variable according to the load and rotational speed, a sufficient intake air cooling effect can be expected. As a result, the air-fuel ratio distribution can be substantially improved and the output performance can be improved.

[Brief explanation of drawings]

Fig. 1 is a graph showing intake temperature vs. output torque and intake air weight vs. characteristics, Fig. 2 is a graph showing air-fuel ratio vs. output torque characteristics, and Fig. 3 is an overall block diagram for explaining the present invention in detail. , FIG. 4 is a graph for detailed explanation of the present invention,
FIG. 5 is a graph showing a two-dimensional map of the injection ratio α according to the present invention, FIG. 6 is an overall schematic diagram showing an embodiment of the fuel supply control device for an internal combustion engine according to the present invention, and FIG. FIG. 8 is a detailed block circuit diagram of the control circuit 10 shown in the figure, and is a flowchart for explaining the operation of the control circuit 10 of FIG. l... Engine main body, 3-1 to 3-2... Main fuel injection valve, 5... Sub-fuel injection valve, 6... Air 7o-meter,
8゜9...Rotation angle up, 10...Control circuit. Patent Applicant Toyota Motor Corporation Patent Application Agent Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Masashi Matsushita Patent Attorney Akira Yamaguchi Patent Attorney Masaya Nishiyama Figure 1 Figure 2 02 01 01 (Rich) )A/(Lean) Figure 4 CA('/,) Figure 5 (Ah) Net High]

Claims (1)

[Scope of Claims] 1. In an internal combustion engine that is provided with a main fuel injection valve provided for each cylinder and an auxiliary fuel injection valve provided in common for each cylinder in the upstream portion of the intake passage, Specified operating state/
a fuel injection amount calculation means for calculating the fuel injection amount according to the engine speed and the rotation speed; a load detection means for detecting the load of the engine; a rotation speed detection means for detecting the rotation speed of the engine; injection ratio calculation means for calculating the injection ratio between the main fuel injection valve and the auxiliary fuel injection valve according to the calculated injection ratio; and a main fuel injection amount calculation unit for calculating the main fuel injection amount from the fuel injection amount according to the calculated injection ratio. means, auxiliary fuel injection amount calculating means for calculating the auxiliary fuel injection amount from the fuel injection amount according to the calculated injection ratio, main fuel injection execution for injecting the main fuel injection amount from the main fuel injection valve. and auxiliary fuel injection execution means for injecting the auxiliary fuel injection amount from the auxiliary fuel injection valve. 2. The injection ratio calculation means calculates the auxiliary fuel injection ratio to be larger as the load and rotation range of the engine becomes higher, and to decrease the auxiliary fuel injection ratio as the load and rotation range of the engine becomes lower. A fuel supply control device for an internal combustion engine according to claim 1.