JPH0441948A - Fuel injector of internal combustion engine for vehicle - Google Patents

Abstract

PURPOSE:To improve acceleration responsiveness without generation of longitudinal oscillation of a vehicle by performing main injection after performing pre- injection when a required injection quantity is changed from a first required injection quantity to a second required injection quantity. CONSTITUTION:In a device which controls fuel injection from a fuel injection valve 2 by an electronic control unit 10, a crank angle sensor 17 and a load sensor 18 are connected to the input port 15 of the electronic control unit 10. A required injection quantity is calculated by a CPU 14 every specified detected timing and when the required injection quantity is increased from the first required injection quantity to the second required injection quantity during the acceleration, main injection is performed after pre-injection is performed. The injection quantity and the injection timing of the pre-injection, and start timing of the main injection, should be so set that a relative twist angle in the case when the main injection is started by the second required injection quantity becomes a focusing twist angle which substantially corresponds to the second required injection quantity, and the relative twist angle is maintained and set to the focusing twist angle which substantially corresponds to the second required injection quantity after starting the main injection.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a fuel injection device for a vehicle internal combustion engine.

[Conventional technology]

In an internal combustion engine that determines the required injection amount from the amount of depression of the accelerator pedal and the engine speed, and injects fuel according to this required injection amount, when the engine output suddenly increases or decreases during acceleration or deceleration, This causes the problem that the vehicle vibrates back and forth. First, the reason why a vehicle generates longitudinal vibration will be explained.

FIG. 14 schematically shows the drive system of the vehicle, where A shows the engine, B shows the engine output shaft, and C shows the power transmission system from the engine output shaft B to the drive wheels.

The power transmission system C includes a clutch, a transmission, a propeller shaft, etc., and each of these elements is collectively shown as a single bar. Expressed in this way, the power transmission system C is twisted when the vehicle is running, and the relative torsion angle that occurs between the two extremes of the power transmission system C at this time is hereinafter referred to as a relative torsion angle. This relative twist angle is indicated by θ in FIG. When the required injection amount is constant and does not change and the vehicle is in steady operation, this relative torsion angle θ is maintained at a constant torsion angle according to the required injection amount, that is, according to the engine output. Hereinafter, this constant twist angle corresponding to the required injection amount will be referred to as a convergence twist angle. This convergent torsion angle is θ1 in FIG. θ,
It is indicated by. That is, in FIG. 15, if the required injection amount is maintained at a constant value Q1 and does not change, and steady operation is performed in this state, the relative torsion angle θ becomes a constant convergence torsion angle θ,
If the required injection amount is maintained at a constant value Q and does not change, and steady operation is performed in this state, the relative torsion angle θ is maintained at a constant convergence torsion angle θ. When steady operation is performed in this manner, the relative torsion angle θ is maintained at a convergence torsion angle corresponding to the required injection amount.

However, during transient operation when the required injection amount changes by 2, the relative torsion angle θ is not maintained at the convergence torsion angle corresponding to the required injection amount (
Become. That is, as shown in Fig. 15, if the accelerator pedal is suddenly depressed and the required injection amount suddenly changes from Q to Q, the engine output will suddenly rise, but since the vehicle has a large mass, the The speed cannot increase immediately to follow the rise in engine power. Therefore, at this time, the relative torsion angle θ is the convergence torsion angle θ according to the required injection amount Qb.

, and a part of the increase in engine output is stored in the power transmission system C as elastic energy. Then, as shown in FIG. 15, the vehicle speed increases and the vehicle acceleration G increases. At this time, in addition to the output torque of the engine, torque due to the elastic energy stored in the power transmission system C is applied to the drive shaft, so the vehicle acceleration G becomes larger than the acceleration G determined by the engine output. When the vehicle acceleration G becomes larger than the acceleration G determined by the engine output, the power transmission system C
The relative torsion angle θ decreases, and the vehicle acceleration G also decreases, so that the relative torsion angle θ becomes smaller than the convergence torsion angle θ corresponding to the required injection amount Q, and the vehicle acceleration G becomes the acceleration G determined by the engine output. becomes smaller than

Therefore, when the required injection amount Q is suddenly increased, the relative torsion angle θ of the power transmission system C oscillates, and the vehicle acceleration G also oscillates, causing the vehicle to vibrate longitudinally. Since the power transmission system C includes a vibration damping system, the amplitude of the relative torsion angle θ and the amplitude of the vehicle acceleration G of the power transmission system C gradually become smaller, and thus the longitudinal vibration of the vehicle is also gradually damped. After the start of acceleration, as the vehicle speed increases, the vehicle acceleration G gradually decreases, but even if the vehicle speed increases, as long as the required injection amount Q remains constant, the driving force for the vehicle remains constant, so the required injection The quantity Q is Q.

As long as θ, the relative torsion angle θ is maintained at θ. Incidentally, as can be seen from FIG. 15, such longitudinal vibration of the vehicle also occurs when the required injection amount Q decreases from Q to Q.

Therefore, in order to reduce the longitudinal vibration of such a vehicle, when the accelerator pedal is suddenly depressed, the required injection amount Q is increased at a predetermined slow speed as shown by the broken line in Fig. 15, and When the amount of depression of the accelerator pedal is suddenly decreased, the required injection amount Q
An internal combustion engine is known in which the engine speed is reduced slowly as shown by the broken line (Japanese Patent Laid-Open No. 60-1999
(See Publication No. 43).

[Problem to be solved by the invention]

However, if the required injection amount Q is changed at a slow speed during transient operation, as shown by the broken line in Fig. 15, the acceleration response of the vehicle will deteriorate because the rise of the vehicle acceleration G will be slow. This causes a problem. Further, if the required injection amount Q is changed at a slow speed during transient operation in this way, although the amplitude of the vehicle acceleration G becomes smaller, there is still the problem that longitudinal vibrations of the vehicle occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection device with good acceleration response without causing longitudinal vibration of a vehicle.

[Means to solve the problem]

In order to solve the above problems, according to the present invention, when steady operation is performed with the first required injection amount, the relative torsion angle between the two extremes of the power transmission system from the engine output shaft to the drive wheels is adjusted to the first required injection amount. The convergence torsion angle is maintained according to the injection amount,
When the fuel injection amount changes from the first required injection amount to the second required injection amount in order to accelerate, the relative torsion angle periodically fluctuates around the convergent torsion angle corresponding to the second required injection amount. , the required injection amount is determined at each predetermined detection timing, and when the required injection amount at two consecutive detection timings increases from the first required injection amount to the second required injection amount, the first required injection amount is determined. The injection control device is equipped with an injection control device that performs main injection after performing preliminary injection by superimposing a preliminary injection amount on the second required injection amount, and when main injection is started with the second required injection amount, the relative torsion angle is approximately equal to the second required injection. The injection quantity of the preliminary injection, the injection timing, and the start timing of the main injection are adjusted so that the convergence torsion angle corresponds to the second required injection quantity and the relative torsion angle is maintained approximately at the convergence torsion angle corresponding to the second required injection quantity after the start of the main injection. I am trying to set it.

[For production]

Using the symbols in FIG. 15, main injection is performed after preliminary injection when the required injection amount changes from the first required injection amount Q1 to the second required injection amount Qb.

The preliminary injection amount is the relative torsion angle θ5 when the relative torsion angle θ of the power transmission system is the second required injection amount Q and the main injection is performed.
The main injection is started when the relative torsion angle θ becomes θ and the relative torsion angle θ can be maintained as it is. Such a preliminary injection action is repeated at each detection timing.

〔Example〕

Referring to FIG. 3, 1 is the engine body, 2 is the fuel injection valve,
Reference numeral 3 indicates an engine output shaft, and 4 indicates a transmission. An output shaft 5 of the transmission 4 is connected to drive wheels. Fuel injection from the fuel injection valve 2 is controlled based on an output signal from an electronic control unit 10.

The electronic control unit 10 consists of a digital computer with ROMs interconnected by a bidirectional bus 11.
(read-only memory) 12, RAM (random access memory) 13, CPU (microprocessor)
14, an input port 5 and an output port 16.

A crank angle sensor 17 and a load sensor 18 are connected to the input port 15 . The crank angle sensor 17 generates an output pulse every time the crankshaft rotates by a certain crank angle, for example 30 degrees, and this output pulse is input to the input port 15. Therefore, the engine speed can be calculated from this output pulse.

On the other hand, the amount of depression of the accelerator pedal 19 is determined by the load sensor 1.
8 performs AD conversion and is input to the input port 15.

The output port 16 is connected to the fuel injection valve 2 via a corresponding drive circuit 20.

Next, the basic principle of the injection control method during transient operation will be explained with reference to FIG.

Referring to FIG. 4(A), when the accelerator pedal is suddenly depressed and the required injection amount Q changes from Ql to Qb, preliminary injection Q is first performed over several cycles, and then the required injection amount Q is changed from Ql to Qb. Q.

The main injection Q2 is performed according to the following. When preliminary injection Q is performed, the engine output rises rapidly, so the relative torsion angle θ of the power transmission system
increases, and as the relative torsion angle θ increases, the vehicle acceleration G increases. Then, the relative torsion angle θ reaches the convergence torsion angle θ determined by the required injection amount Q, and the vehicle acceleration G reaches the main injection Q.
Main injection Q2 is started when the vehicle acceleration G at the start of 2 becomes equal to G. If the main injection Q2 is started at such a time, the vehicle acceleration G after the start of acceleration is maintained at G, so that the vehicle does not generate longitudinal vibration. That is, the amount of preliminary injection Q1 is determined so that the relative torsion angle θ becomes θ during acceleration driving, and the relative torsion angle θ becomes θ5 and the vehicle acceleration G
If main injection Q2 is started when Gb becomes Gb, the vehicle will no longer experience longitudinal vibration. Figure 4 (D) shows a case where the power transmission system does not have a vibration damping system, and in this case, the required injection amount Q is reached when the vehicle acceleration G reaches its peak.
The acceleration G immediately after acceleration corresponds to 2. However, in reality, the power transmission system includes a vibration damping system, and in this case, in addition to the energy required to set the relative torsion angle θ of the power transmission system to θ, the energy consumed by the vibration damping system is An output must be given, and a portion of the energy consumed by the vibration damping system gives an acceleration G to the vehicle. Therefore, if the power transmission system has a vibration damping system, as shown in Fig. 4 (
As shown in A), the vehicle acceleration G temporarily becomes larger than G until the relative torsion angle θ reaches θ.

FIG. 4(A) shows that the injection quantity in each cycle in which preliminary injection Q1 is performed is equal to the required injection quantity Qb in each cycle of main injection Q, and that the injection quantity between preliminary injection Q and main injection 02 is Ql.
This shows the case where a certain cycle is involved. However, as shown in FIG. 4(B), it is also possible to make the injection amount in each cycle of the preliminary injection Q smaller than the injection amount in each cycle of the main injection Q2, and to perform the main injection Q2 following the preliminary injection Q1. However, as shown in FIG. 4(C), the injection amount in each cycle of the preliminary injection Q can also be varied in a curved manner.

During deceleration operation, the injection amount is temporarily reduced using the same concept as acceleration, and then the required injection amount is set after a while. In this case as well, there are various ways to reduce the amount, as shown in FIGS. 4(A) to 4(C).

Next, with reference to FIGS. 5 and 6, analysis results regarding the injection period and injection amount of the preliminary injection and the injection start timing of the main injection will be explained.

In the analysis, the controlled object is first modeled as shown in FIG.

As shown in FIG. 5, an engine of mass m and an engine of mass m.

It is assumed that the vehicle is connected by a power transmission system with a spring constant and a damping coefficient C, and the engine has a driving force F.

The displacement of the engine when this occurs is Xl, and the displacement of the vehicle is x2
shall be. The radius of the drive wheel is r, and the displacement of the engine output shaft is X +
When expressed in (rad), Xl·r =x, so the mass m of the engine represents an equivalent mass taking this relationship into consideration. In addition, the driving force F of the engine.

corresponds to the required injection amount.

Regarding the injection pattern, as shown in Fig. 6, a driving force F at is generated in the engine during a certain preliminary injection period t1 from when the accelerator pedal is suddenly depressed, that is, the required injection amount is maintained over several cycles. F. , and after the accelerator pedal is depressed after this preliminary injection period has elapsed, t
It is assumed that the required driving force F0 is generated after 8 hours, that is, the required injection amount F0 is injected.

The following analysis will be conducted under these conditions.

First, if we set up a differential equation for the model in Figure 5, we get the following.

m1°X+=F+ (t)-kcxr-xi>-c(x
I-xz) ・” (1)mz'Xz=k(X
l-Xz)+C(M+-Xz) ”・(
2) F(s)=L[F+(t)], x+(o)=xz
(o)=O.

;t, (o)=i2(o)=0, (1), (2
) is converted to Laplace transform, and it becomes as follows.

m, S"x, = F(s)-kx, +kxz-cSx, +
cSx2”・(3)m2S2x2
=kx yi-kxz +csx, -cSxz
-(4) Solving equations (3) and (4) for X I + X t yields the following.

If a unit impulse is added as input, F(s)
=1, and in this case, equation (6) can be expressed as follows.

here When formula (7) is inversely transformed, it becomes the following formula.

... (8) (8) Sentence about 2. , Ken2 is calculated as follows.

Next, the acceleration 2 of the vehicle when the rectangular wave F of tI is applied is determined by the following equation by superimposing the acceleration 2 when applying the unit impulse expressed by equation (10).

... (12) Next, find the transient displacement of the spring extension of the power transmission system whose spring constant is k.

Dividing equation (1) by m, dividing equation (2) by m = (1)
, by subtracting each side of equation (2), we get the following.

Solving equation (11) yields the following.

x12=)(,xz) and then Laplace transform the equation (13), and inversely transform it with the addition of a unit impulse, the equation (13) becomes as follows.

Next, a square wave F of 1. The transient displacement x, □ of the spring when .

sin ,,ITT7cr(1) o(t −r )d
r − (15) Solving equation (15) yields the following.

Next, as shown in FIG. 16, we will examine the conditions under which the vehicle does not vibrate when a driving force Fo is applied to the engine after a certain period of time when the accelerator pedal is depressed hard.

The condition that the vehicle does not generate longitudinal vibration when the driving force Fo is applied to the engine is that the acceleration of the vehicle does not change when the driving force Fo is applied to the engine. In other words, two conditions must be simultaneously satisfied: the transient displacement χ,2 of the spring does not change before and after the driving force Fo is applied to the engine, and the acceleration of the vehicle does not change.

If the acceleration of the vehicle when a driving force Fo is applied to the engine is a5, these two conditions can be expressed as follows.

... (16) Equation (17) is 1=1. Spring force kx, □(t,) at
is equal to the force acting on the spring when a driving force Fo is applied to the engine. In other words, the spring force kx before and after the driving force Fo is applied to the engine
, 2 do not change, that is, the transient displacement X1□ of the spring does not change.

On the other hand, equation (18) is 1=1. The vehicle acceleration L(t
, ) is equal to the acceleration a8 of the vehicle when the driving force Fo is applied to the engine, that is, the acceleration father 2 of the vehicle immediately before the driving force Fo is applied to the engine is equal to the acceleration a8 of the vehicle when the driving force Fo is applied to the engine. It represents that it is equal to the acceleration a of the vehicle when

In other words, if formula (18) is satisfied but formula (17) is not satisfied, the vehicle will vibrate back and forth because positive or negative acceleration will act on the vehicle due to the spring force kx1z when the driving force F0 is generated. , (17) is satisfied, but (18)
If the formula is not satisfied, the driving force F.

When this happens, the driving force F0 applies positive or negative acceleration to the vehicle, causing the vehicle to vibrate back and forth.

Therefore, in order to prevent the vehicle from generating longitudinal vibration when the driving force F0 is generated, it is necessary to simultaneously satisfy equations (17) and (18).

By the way, the transient displacement x, □ of the spring corresponds to the relative torsion angle θ of the power transmission system, and therefore, equation (17) means that the relative torsion angle θ does not change before and after the generation of the driving force F0. . In other words, it means that the relative torsion angle θ becomes the convergent torsion angle determined by the driving force F0 immediately before the driving force F0 is generated.

On the other hand, if equation (18) is not satisfied and the vehicle vibrates back and forth, the relative torsion angle θ will oscillate around the convergent torsion angle determined by the driving force F0. The twist angle θ is maintained at a convergent twist angle. Therefore, satisfying equations (17) and (18) at the same time means that the relative torsion angle θ becomes the convergent torsion angle immediately before the generation of the driving force F0, and the relative torsion angle becomes the convergent torsion angle after the generation of the driving force F0. means to be maintained.

Therefore, the relative torsion angle θ becomes the convergent torsion angle immediately before the generation of the driving force F0, and the relative torsion angle is maintained at the convergent torsion angle after the generation of the driving force F0, that is, equations (17) and (18)
If the injection amount, injection timing, and main injection start timing of the preliminary injection are determined so that the equations are simultaneously satisfied, the vehicle will not generate longitudinal vibration.

Next, the injection amount, injection timing, and main injection start timing of the preliminary injection that satisfy the equations (17) and (18) are determined.

First of all, eliminate χ1□ from equations (16) and (17), and get f″X′ −, P , A=(” a.t, = x , J
"If we set esot+ = V, we can obtain the following equation.

Next, equation (19)2 - (20), and equation (19) + (2
0) Calculating 2 is as follows.

e'5in(x-y)-sinx =0
- (21)... (n2) The following two equations are found from these equations (21) and (22).

... (23) Next, by eliminating equation 2 from equations (12) and (18), the following equation is obtained.

... (24) (23) Ninomu is a function of Ll, and F in equation (24)
oi is a function of ,t,. Therefore, first of all, if we set ``mu'' to an appropriate value, we can find Ll from equation (23), F Oi from equation (24), and set the preliminary injection amount to F.
If oi, the preliminary injection time is 1+, and the main injection start time is t, the vehicle will not cause longitudinal vibration during acceleration operation. Further, as shown in Fig. 6, the injection amount is decreased by F of over a period of time L1 from the time when the amount of depression of the accelerator pedal is suddenly decreased, and after 1 s from the time when the amount of depression of the accelerator pedal is decreased. If the required injection amount is set, it is possible to prevent the vehicle from causing longitudinal vibration during deceleration driving.

As shown in FIG. 7, the preliminary injection amount Foi varies depending on how t is set. In this case, any preliminary injection pattern may be adopted.

If the power transmission system does not have a vibration damping system, t I, t
The relationship between -, F o, and F ot is extremely simple as shown in the following equation.

In this case, if F,=F,i, the injection pattern will be as shown in FIG. 8(A), and if F,i−F,/2, the injection pattern will be as shown in FIG. 8(B).

In Figure 9, the amount of depression of the accelerator pedal increases instantaneously and the required injection amount is Q. A case is shown in which the basic principle according to the present invention is applied to a case where Ld increases instantaneously to Q n @W.

Figure 9 (A) shows the case where the preliminary injection amount is the same as the main injection amount, and in this case, equations (23) and (24)
From the formula 1. ．． 1. is uniquely determined. Therefore, in this case, the injection amount in each cycle during the time t1 after the accelerator pedal is depressed is set as the required injection amount Q7-,
The injection amount in each cycle from the time t1 has passed until the time L5 has passed is the required injection amount Q o L d, and the injection amount in each cycle after the time t8 has passed is the required injection amount Q. If it is set to a, the vehicle will not experience longitudinal vibration after acceleration.

On the other hand, FIG. 9(B) shows the preliminary injection period 1. The case is shown in which L5 and F are equal to L5. ,
/F0 is uniquely determined. In addition, in Fig. 9(B), α(
-1-F, , /F0) is used, and this α is uniquely determined. In this case ΔQ = Qna
If w Qota is assumed, the injection amount in each cycle during the 3 hours after the accelerator pedal is depressed is (Q-8-α・ΔQ), and the injection amount in each cycle after the elapse of ts is the required injection amount Q,... , w, the vehicle will not experience longitudinal vibration after acceleration.

When the amount of depression of the accelerator pedal changes in a stepwise manner as described above, by employing the injection method shown in FIG. 9(A) or (B), it is possible to suppress the occurrence of longitudinal vibration of the vehicle after acceleration.

However, in reality, the amount of depression of the accelerator pedal does not change in a stepwise manner, and in this case, in FIG. 9(A) or (
The injection method shown in B) cannot be used as is.

However, even if the amount of depression of the accelerator pedal does not change stepwise, it is possible to prevent longitudinal vibration of the vehicle after acceleration by using the basic principle shown in Figure 9 (A) or (B). , the method is shown in Figures 1 and 2.
As shown in the figure.

Figure 1 shows the case where the basic principle shown in Figure 9 (A) is used when the amount of depression of the accelerator pedal does not change in steps, and Figure 2 shows the case where the amount of depression of the accelerator pedal changes in steps. This figure shows a case where the basic principle shown in FIG. 9(B) is used in the case where the above is not used. First, an injection method when the amount of depression of the accelerator pedal does not change stepwise will be described with reference to FIG.

As shown in FIG. 1, if the amount of depression of the accelerator pedal changes, then predetermined detection timings t+, tz, t3. Depress the accelerator pedal every tn ii L+. L2. L,,L, are detected, and these stepping ML,,L,,L3. Requested injection amount Qnaw+ l Qnawz l QnnW3 I Q
,, find ew4.

Then, at each detection timing L+, Lz, tz, and j4, the preliminary injection amount and the main injection amount are determined according to the basic principle shown in FIG. 9(A), and these are sequentially superimposed. That is, the required injection amount before reaching the detection timing L is Q. Ldl
If so, at the detection timing t1, the required injection amount Q n @ starts from the accelerator pedal depression I L+.
After calculating w+ and performing preliminary injection at 3 hours required injection amount Qas, (ts-t+) time required injection amount QoL
The fuel is injected at d+, and then the main injection is performed at the required injection amount QnaW+. Next, at detection timing L2, t is reached at the required injection amount Q7-2 obtained from the accelerator pedal depression amount L2.
Perform preliminary injection for 3 hours, then inject at the required injection amount Qnewl for (1-1+) hours, then inject at the required injection amount Q. Perform main injection at o2. In this way, it is assumed that the amount of depression of the accelerator pedal changes stepwise at each detection timing, that is, for example, at detection timing t2, the amount of depression of the accelerator pedal changes stepwise from Ll to Ll. At each detection timing, the preliminary injection amount and the main injection amount are calculated based on the required injection amount at the previous detection timing based on the basic principle shown in FIG. 9(A),
These are sequentially superimposed at each detection timing. In this way, the power transmission system is twisted by the injection control at each detection timing, and control is performed so that longitudinal vibration does not occur in the vehicle at the start of main injection, so longitudinal vibration occurs in the vehicle after acceleration due to the principle of superposition. I will not do it.

In the embodiment shown in FIG. 1, the interval between detection timings is also made to match, so that, for example, at detection timing t2, the required injection amount appears to be Q. 88. The main injection is not performed by
Requested injection amount Q. -2 preliminary injection is performed. In this case, if the detection timing interval is made longer than L5, the preliminary injection with the required injection amount Q788□ will be performed after the main injection with the required injection amount Q n 11 W +. However, if the interval between the detection timings is made to match ts, the routine for injection control becomes extremely complicated, so in the embodiment shown in FIG. 1, the interval between the detection timings is made to match L5.

FIG. 2 shows a case where the basic principle shown in FIG. 9(B) is used, and in this case as well, as shown in FIG. 2, the predetermined detection timing 1. ．． Depress the accelerator pedal every 12Ls, La, Ll.

L3. Detect L4, and measure these steps, Ll, L
Requested injection amount Q newW+ + Qnew according to 3L4
Find z l Qhaw3Q rl a W 4. And each detection timing 1. , 12Lx, and L4, the preliminary injection amount and main injection amount are determined in accordance with the basic principle shown in FIG. 9(B), and these are sequentially superimposed. That is, the required injection amount before reaching the detection timing t is Q. If it is 4.1, the required injection amount Q7° is calculated from the detection timing L and the amount of accelerator pedal depression detected by smell.
After preliminary injection is performed with the ts time injection amount α· (Q, , , -Q.l□), main injection is performed with the required injection amount Qnawl. Next, at detection timing L2, the required injection amount Q7°1z is determined from the accelerator pedal depression amount L2, and the injection amount α
' (Qnewz Qnewl) After performing preliminary injection for t5 hours, main injection is performed with the required injection amount Q788□.

In this way, it is assumed that the amount of depression of the accelerator pedal changes stepwise at each detection timing, that is, for example, at detection timing L2, the amount of depression of the accelerator pedal increases, and then changes from Ll in a stepwise manner. For each detection timing, the basic principle shown in Figure 9 (B) is revealed, and the preliminary injection amount and main injection amount are calculated based on the required injection amount at the previous detection timing, and these are sequentially superimposed for each detection timing. . In this way, the injection control at each detection timing gives twist to the power transmission system and controls the vehicle so that longitudinal vibration does not occur at the start of main injection. No back-and-forth vibration will occur.

In the embodiment shown in FIG. 2, the detection timing interval is made to coincide with t, so that, for example, at the detection timing tz, the main injection with the required injection amount Q f, a W I is not apparently performed, but the injection amount α・( A preliminary injection is performed with Qn, , -Q, d,). In this case, if the detection timing interval is made longer than L5, the required injection amount Q fi e W
After the main injection is performed by +, the injection amount α・(Qnawl
A preliminary injection will be performed by Ql)ldl). However, if the detection timing interval is set to match t5, the injection control routine becomes extremely simple, so the embodiment shown in FIG. 2 also sets the detection timing interval to 1.5. is matched.

Next, while referring to Figures 1 and 2,
A method of calculating the actual injection amount will be explained with reference to FIG.

Figure 10 shows a routine for calculating the required injection amount according to the amount of depression of the accelerator pedal.
This is common to both injection methods shown in FIG. Note that this routine is executed by a time interrupt every 2 m5ec.

Referring to FIG. 10, first, in step 100, a count value CTS is incremented by one. Next, in step 101, the count value CTS becomes 1. It is determined whether or not it is equal to /2. In the embodiment shown in FIGS. 1 and 2, t is preset to = 140 m5ec, so in step 101 the count value CT
The count value (t, /
2 = 70). When the count value CTS is not t5/2, the processing routine is completed, and when the count value CTS is less than t5/2 and becomes equal to /2, the process proceeds to step 102 and CTS is set to 0. Therefore, the count value CTS is set to zero every 140 m5ec, that is, every time ts, as shown in FIGS. 1 and 2.
The count-up action then begins. Count value C
The detection timings t+, tz, t3+ti in FIGS. 1 and 2 are when TS becomes zero, and therefore the detection timings are 14 in the embodiment shown in FIGS. 1 and 2.
It has a constant cycle of every 0m5ec.

When the count value CTS is set to zero in step 102, that is, when the detection timing is reached, the process proceeds to step 103 and the required injection amount Q7 calculated at the previous detection timing is
°8 is taken as Qo, 4. Next, in step 104, the required injection amount Q is determined from the output signal of the load sensor 18 representing the current depression ML of the accelerator pedal 19 and the engine speed NE.
n*w is calculated. This required injection amount Q Ra
The relationship between hj, the amount of depression of the accelerator pedal 19, and the engine speed NE is stored in advance in the ROM 12 in the form of a map as shown in FIG.

FIG. 11 shows a routine for executing the injection control shown in FIG. 1, and this routine is executed by interruption at every fixed crank angle.

Referring to FIG. 11, in step 200, it is determined whether the count value CTS is smaller than t1/2, that is, whether one hour has elapsed from the detection timing. 11
If the time has not elapsed, the injection amount is the required injection amount Q n
Then, in step 203, the fuel injection valve 2 performs an injection operation.

On the other hand, when 11 hours have passed, the process proceeds to step 202, where the injection amount Q is set to the required injection amount Q0,4, and step 20
Proceed to step 3.

FIG. 12 shows a routine for executing the injection control shown in FIG. 2, and this routine is executed by interruption at every fixed crank angle.

Referring to FIG. 12, in step 300 ΔQ(=
Qn, , −Q, , ) is calculated and then step 30
1, the injection IQ is calculated by subtracting α·ΔQ from Q n a w. Then step 302
Injection from the fuel injection valve 2 is performed.

In addition, during steady operation, Q n@W :Q6ta,
Therefore, it can be seen from FIGS. 11 and 12 that the required injection amount at this time is Qn aw. In addition, if the injection method shown in Fig. 1 is adopted as shown in the routine of Fig. 11, the injection pattern shown in Fig. 4 (A) will be superimposed during deceleration operation, and as shown in the routine of Fig. 12. When the injection method shown in FIG. 2 is employed, the injection patterns shown in FIG. 4(B) are superimposed during deceleration operation.

[Effects of the Invention] Acceleration operation with good responsiveness can be achieved without causing longitudinal vibration in the vehicle.

[Brief explanation of drawings]

Fig. 1 is a time chart showing a first embodiment of the injection pattern during acceleration, Fig. 2 is a time chart showing a second embodiment of the injection pattern during acceleration, Fig. 3 is an overall view of the internal combustion engine, and Fig. 4 is a time chart showing a second embodiment of the injection pattern during acceleration. The figure shows various basic injection patterns, and Figure 5 shows the control pattern. Figure 6 is a diagram showing the basic injection pattern, Figure 7 is a diagram showing various basic preliminary injection patterns, and Figure 8 is a diagram modeling the H target. Figure 9 is a time chart, Figure 10 is a flowchart for calculating the injection amount, and Figure 11 is a flowchart for performing the injection control shown in Figure 1. , FIG. 12 is a flowchart for performing the injection control shown in FIG.
FIG. 3 is a diagram showing the required injection amount, FIG. 14 is a diagram schematically showing the drive system of the vehicle, and FIG. 15 is a time chart for explaining the longitudinal vibration of the vehicle that occurs during acceleration. 2... Fuel injection valve, 3... Engine output shaft, m
,...Equivalent mass of the engine, m2...Mass of the vehicle, k
... Spring constant of the power transmission system, C... Damping coefficient of the power transmission system. Figure 3rd 2...Fuel injection valve 5 - engine output shaft 4th (A) Group (C) Figure (B) Group (D) Figure (A) Figure (B) Episode (A) Figure (B) Figure 12 Figure 10] 3rd Figure E

Claims (1)

[Claims] During steady operation with the first required injection amount, the relative torsion angle between the two extremes of the power transmission system from the engine output shaft to the drive wheels is maintained at a convergent torsion angle corresponding to the first required injection amount, resulting in acceleration. In a vehicle in which when the fuel injection amount changes from the first required injection amount to the second required injection amount, the relative torsion angle periodically fluctuates around a convergent torsion angle corresponding to the second required injection amount. , the required injection amount is determined at each predetermined detection timing, and the required injection amount at two consecutive detection timings is changed from the first required injection amount to the second required injection amount.
an injection control device that superimposes a preliminary injection quantity on a first required injection quantity to perform a preliminary injection and then performs a main injection when the required injection quantity increases to a second required injection quantity; The above-mentioned relative torsion angle when injection is started becomes a convergence torsion angle that substantially corresponds to the second required injection amount, and after the start of main injection, the above-mentioned relative torsion angle is maintained at a convergence torsion angle that approximately corresponds to the second required injection amount. A fuel injection device for a vehicle internal combustion engine, in which the injection amount, injection timing, and main injection start timing of preliminary injection are set so as to be performed.