JPS6336038A - Fuel feeding quantity control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the accuracy of air fuel ratio control by calculating a moderating coefficient based on engine operating condition factors such as the changing rate of intake air quantity - engine speed ratio, engine speed, etc. and injecting a fuel of a fuel injection quantity which is moderated by said moderating coefficient. CONSTITUTION:During the operation of an internal combustion engine, a control circuit 42 inputted an intake air quantity - engine speed ratio which represents the load of the engine in a QN and, then, judges whether the QN is larger than the moderating value QNSTi-1 of the QN which is obtained at the time of executing the last routine. When it is YES (accelerating), for example, a moderating coefficient K2 corresponding to an intake air quantity changing rate DELTAQN at that time is operated by map. And, a moderating coefficient K1 corresponding to an engine speed is also operated by map, and the product of multiplying both coefficients K1, K2 is used as the final moderating value to operate a moderating value QNST at the time of accelerating. And, the fuel injection quantity is operated based on this QNST, to control a fuel injection valve 25.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a fuel supply amount control device for an internal combustion engine.

[Conventional technology]

Between internal combustion stages, for example, in a fuel injection type internal combustion engine, a fuel supply amount is calculated according to various operating conditions of the engine, and a fuel injection valve is driven so that the calculated amount of fuel is supplied. Although the engine load is an operating condition, it is common to detect the ratio of intake air amount to rotation speed as a representative factor of the load. The amount of intake air is measured by an air flow meter or the like. However, the detected value of a volume flow type intake air amount detector such as an air flow meter does not transiently represent an accurate state of the intake air amount. In a transient state (acceleration) when the throttle valve is driven from closed to open, the air flow meter measures not only the amount of air filling the engine combustion chamber, but also the amount of air filling the intake pipe from downstream of the throttle valve to the combustion chamber. Also measured. This means that the air flow meter measures a larger value as the amount of intake air than the amount of air actually supplied to the engine (overshoot). Conversely, in a transient state (deceleration) in which the throttle valve is driven from open to closed, it is not possible to measure the fuel that enters the combustion chamber and is filled in the intake pipe from the throttle valve to the combustion chamber. That is,
Air flow make measures a value smaller than the amount of air actually supplied to the engine as the amount of intake air (undershoot). Therefore, in order to correct the measured value of the air flow meter to the intake air level required by the actual engine during a transient period, the rate of change in the measured value of the air flow meter is made to match the actual rate of change in the amount of intake air required by the engine. In order to achieve this, the air flow meter measurement values are blunted (so-called smoothing).

[Problem that the invention seeks to solve]

In the conventional technology, the blunting rate (smoothing coefficient) was determined by detecting a specific operating state such as the throttle valve opening, the rate of change in the throttle valve opening, or the rate of change in the rotation speed (for example, JP-A-59-170442). However, simply determining the smoothing coefficient based on one type of engine operating condition does not accurately compensate for the amount of intake air detected by the air flow meter in a transient state. This is particularly a problem in internal combustion engines equipped with a supercharger where the volume of the intake pipe from the throttle valve to the combustion chamber is large.

As a result, there has been a problem in that the deviation in air-fuel ratio becomes large, resulting in deterioration in emissions, drivability, and fuel consumption rate.

[Means for solving problems]

In FIG. 1, the fuel supply amount control device for an internal combustion engine according to the present invention includes a fuel supply means 1 for supplying fuel to the internal combustion engine, a means 2 for calculating the amount of fuel to be supplied to the internal combustion engine, and a fuel supply means 1 for supplying fuel to the internal combustion engine. a first detecting means 3 for detecting a first operating state of the internal combustion engine; a second detecting means 4 for detecting a second operating state of the internal combustion engine; It is comprised of a means 5 for obtaining a slowed fuel supply amount, and a means 6 for controlling the fuel supply means 1 so that a quantity of fuel corresponding to the slowed fuel supply amount is supplied to the engine.

〔Example〕

In Fig. 2, 10 is a solid cylinder block, 12 is a piston, 14 is a connecting rod, 15 is a crankshaft,
16 is a combustion chamber, 18 is a cylinder cylinder 1-122 is an intake valve, 24 is an intake boat, 25 is a fuel injection valve, 26 is an exhaust valve, and 28 is an exhaust port. The intake port 24 is connected to an air flow meter 34 via a surge tank 29, an intercooler 30, a mechanical supercharger 31, and a throttle valve 32. 38 is a distributor.

The mechanical supercharger 31 is configured as, for example, a Roots pump, and a pulley 33 is provided on its rotating shaft 31a.

The pulley 33 is connected to a pulley 36 on the crankshaft 15 via a heald 35. A pulley 33 on the rotating shaft 31a of the supercharger i31 is provided with an electromagnetic clutch 37. The electromagnetic clutch 37 is released at low rotation and low load, and the rotation of the crankshaft 15 is not transmitted to the supercharger 31. On the other hand, at high rotations and high loads, the electromagnetic clutch 37 is engaged and the crankshaft 15
The rotation is transmitted to the supercharger 31 to perform supercharging operation.

42 is a control circuit as a microcomputer;
Performs necessary calculations based on signals from various sensors,
It is programmed to form a fuel injection signal to the fuel injector 25 and a drive signal to the supercharger actuating clutch 37. The control circuit 42 includes a central processing unit (CPU) 44,
A memory 46, a human powered boat 48, an output port 50,
The basic component is a bus 52 that connects these. The following sensors are connected to the input boat 48. The air flow meter 34 supplies a signal corresponding to the intake air iQ. Crank angle sensors 56 and 58 are installed in the distributor 38.

The first crank angle sensor 56 is connected to the distributor shaft 3
Generates a signal G every 8′ rotation, that is, every 720° CA,
It becomes a reference signal. - The crank angle sensor 58 of the old handwriting 2 generates a signal NE every 30° of the crankshaft, allowing the engine speed to be determined in a well-known manner. Other sensors are also installed, but since they are not directly related to this invention, their explanation will be omitted.

The output port 50 is connected to the fuel injection valve 25 via a fuel injection valve drive circuit 64. The drive circuit 64 consists of a comparison register 66, gates 68, 70, and a bistable circuit 72. Bistable circuit 72 is set by gate 68 and reset by gate 70. One input of the comparison register 66 is connected to a free run counter (used to know the current time) 73 of the control circuit 42. Note that the drive circuit is merely an example, and other types of drive circuits may be employed. In addition, the output port 5o is the electromagnetic clutch 3 of the supercharger.
Connected to 8.

The operation of the control circuit 42 will be explained below using a flowchart. It should be noted that the control of the electromagnetic clutch that operates the supercharger itself is not directly related to the present invention, so a description thereof will be omitted.

FIG. 3 shows a fuel injection amount calculation routine, which is executed within the main routine every 4 msec, for example. In step 100, the intake air amount to revolution speed ratio Q/N E representing the engine load is entered into QN.

In step 102, it is determined whether QN≧QNST=-+. Here, QNST, , □I are the rounded values of the intake air amount to revolution speed ratio obtained the last time this routine was executed.

When the engine accelerates, it is determined as Yes, and step 104
Then, 2 is mapped to the smoothing coefficient corresponding to the rate of change in intake air amount during acceleration. FIG. 6 shows the relationship between the intake air amount change rate ΔQN and 2, and the value of 2 is set to be smaller as ΔQN is larger, that is, the degree of improvement is smaller. This relationship is stored in memory 46 as a map. ΔQN can be determined from the difference between the intake air amount to rotation speed ratio when this routine was executed last time and the intake air amount to rotation speed ratio when this routine was executed this time. A value of 2 corresponding to the thus known ΔQN is calculated by interpolation.

In step 106, a smoothing coefficient Kl is calculated according to the engine speed. FIG. 7 shows the relationship between the engine speed NE and the smoothing coefficient of 1. The higher the engine speed, the smaller the smoothing coefficient is, that is, the degree of smoothing is set to be smaller. The relationship shown in FIG. 7 is stored in the memory 46 as a two-dimensional map. Then, 1 is interpolated as a correction coefficient based on the actually measured engine rotation speed NE.

In step 108, 1 and 2 are calculated as the final smoothing coefficient during acceleration.

In step 110, the calculation of the rounded value QNTS of the intake air amount-to-rotation speed ratio during acceleration is calculated as QNTS-((K-1
)QNTS, , +QN)/. This formula shows that the smoothed value QNTS is the current intake air amount/rotation speed ratio Q
A weight of 1 is applied to N, and the previous rounded value Q N T S =I
This means that it is an average value with a weight of -1.

That is, the intake air amount-to-rotation speed ratio is corrected so that it becomes a more modest value than the actual intake air amount-to-rotation speed ratio QN.

Since QN<QNTSi- during deceleration operation, the process proceeds from step 102 to step 112, where 4 is mapped to the smoothing coefficient corresponding to the rate of change in intake air amount during deceleration. A relationship between ΔQN and 4 similar to that shown in FIG. 6 is stored in the memory, and a value of 2 corresponding to ΔQN is calculated by interpolation.

In step 114, a calculation of 3 is performed on the smoothing coefficient according to the engine speed. The relationship between the engine speed NB and the smoothing coefficient 9 equal to 3 as shown in FIG. 7 is stored in the memory, and the correction coefficient 3 is interpolated from the actually measured engine speed NE.

In step 116, the product of 3 and 4 is set as a Q-like smoothing coefficient during deceleration.

In step 118, the calculation of the smoothed value QNTS of the intake air h1-rotation speed ratio during deceleration is performed as follows: QNTS=((K-
1) Executed by QNTSi-, -QN)/. In this formula, the smoothing value QNT S gives a weight of 1 to the current intake air amount/revolution speed ratio QN, and the previous smoothing value QNTS
This means that it is an average value with a weight of -1.

That is, the intake air amount-to-rotation speed ratio is corrected so that it becomes a value somewhat larger than the actual intake air amount-to-rotation speed ratio QN.

In step 120, the basic injection FITP is determined such that TP=CXQ
Calculated by NTS. Here, k is a constant D-t1'.

In Step 122, the final injection 1 TAU is TAU = TPX
Calculated by α(1+β)+γ. Here, α, β, and T represent various correction factors such as feedback, water temperature, and acceleration.

In step 124, the current rounded value QNTS is determined as Q N
It is stored at address T S i -1 and used in the next routine.

FIG. 4 shows a crank angle interrupt routine, which is executed by detecting the crank angle before the fuel injection timing by the crank angle sensors 56 and 58. In step 126, the fuel start time is determined.

is calculated. In step 128, the injection end time is calculated. 1. ．． 1. In the case of cylinder-specific injection, the final injection time TA is calculated so that the injection is performed during the intake stroke.
It can be calculated more easily than U. In step 130, the injection start time is determined.

is set in comparison register 66. At step 130, the interrupt permission flag FA is set, and the fuel injection prohibition flag F is reset.

When the injection start time t arrives, the values of both inputs of the comparison register 66 match, so the register outputs the t(high signal, and the note gate 68 with FA=1.Fn=Q turns O.
N, the bistable circuit 74 is turned on, and the fuel injection valve 25
At the same time that the next fuel injection is started, the time coincidence interrupt routine shown in FIG. 5 is activated. In step 134, the injection end time t is entered in the comparison register 66.

At step 136, flag FA is reset and flag FB is set. When the injection end time t arrives, both inputs of the comparison register 66 match, so the old F and h signals are output. Since the flags are FA-0 and Fs-1, the gate 70 is turned on, the bistable circuit 72 is reset, and the fuel injection valve 25 is closed. Fuel injection of the amount TAU calculated in this way is carried out during a desired stroke of the engine.

FIG. 8 is a diagram illustrating the invention in detail.

When accelerated operation is performed, the opening degree of the throttle valve increases rapidly. The change in the intake air amount-to-rotation speed ratio QN exhibits an overshoot as shown in ll. The smoothed value QNTS changes as m. The diagonal line corresponds to the amount of air to fill the intake system volume. If there is no smoothing process, the air-fuel ratio will shift rich as shown in 12. The air-fuel ratio is controlled to the set air-fuel ratio as m2 by smoothing.

〔Effect of the invention〕

In this invention, since the smoothing coefficient is calculated based on multiple engine operating condition factors such as the rate of change in the ratio of intake air amount to rotational speed and the engine speed, it is possible to perform smoothing processing that is more suitable for the engine condition. This makes it possible to control the air-fuel ratio to the set value with high precision. Therefore, it is possible to reduce emissions, improve drivability, and increase fuel consumption.

In the embodiment, the ratio of intake air amount to revolution speed is smoothed, but the intake air amount itself may be smoothed, or the basic injection amount may be smoothed.

Further, although the embodiment describes a fuel injection system, other fuel supply systems may also be employed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of this invention. FIG. 2 is a configuration diagram of the embodiment. 3 to 5 are flowcharts illustrating the operation of the control circuit. Figures 6 and 7 show the smoothing coefficient of 2. Graph showing Kl settings. FIG. 8 is a timing diagram illustrating the invention in detail. 25...Fuel injection valve 32...Throttle valve 34...Air flow meter 38...Distributor 42...Control circuit 56.58...Crank angle sensor Fig. 4 Small dog △QN Fig. 7 Figure 8

Claims (1)

[Scope of Claims] A fuel supply amount control device for an internal combustion engine comprising the following components, a fuel supply means for supplying fuel to the internal combustion engine, a means for calculating the amount of fuel to be supplied to the internal combustion engine, and a fuel supply amount control device for an internal combustion engine. 1st
a first detection means for detecting an operating state of the internal combustion engine; a second detecting means for detecting a second operating state of the internal combustion engine; and a second detecting means for detecting a second operating state of the internal combustion engine; means for controlling the fuel supply means so that an amount of fuel is supplied to the engine in accordance with the slowed fuel supply amount;