JPH01151740A - Fuel control device for engine - Google Patents

Abstract

PURPOSE:To improve combustibility during acceleration, by a method wherein, in an engine with a valve mechanism adapted to create a swirl, when the motion timing of the valve mechanism falls on a fuel increase during acceleration, the fuel increase is suppressed. CONSTITUTION:An intake air passage on the downstream of a surge tank 13 located in an intake air passage 9 is divided into an auxiliary intake air passage 9A and a main intake air passage 9B, pointed in the direction of the tangential line of a combustion chamber 4, by means of a partition wall 14. A shutter valve 15 and a fuel injection valve 16 are disposed in the auxiliary intake air passage 9A. Through closing of the shutter valve 15 during low load running, the velocity of flow of intake air introduced through the main intake air passage 9B is increased, and a sufficient swirl is generated in a combustion chamber 4. In this case, when the shutter valve 15 is opened from a closed state during acceleration or under acceleration, an acceleration increase by which an amount of fuel injected from the fuel injection valve 16 is increased during acceleration is suppressed, and this constitution stabilizes combustibility, and improves fuel consumption and exhaust emission.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel control device for an engine, and more particularly to improving combustibility during acceleration in an engine having a swirl generation mechanism.

[Prior Art] Conventionally, engines with a swirl generation mechanism have been realized as engines aimed at reducing fuel consumption, etc. (for example,
JP 56-126615).

Such an engine includes a low-load intake passage for generating a swirl in the engine combustion chamber during low-load conditions, and a high-load intake passage provided with an on-off valve that closes during low-load conditions. Then, by closing the on-off valve and closing the intake passage for high loads during low loads, a swirl is generated to increase the combustion speed in the steady rotation range or low load range, improving combustion efficiency and achieving the best fuel efficiency. and to realize a reduction in HC emissions. Particularly in the low load range, the flow rate of the lean mixture is increased and swirl is generated, which impairs complete combustion of the mixture.

On the other hand, there is also an engine, such as Japanese Patent Application Laid-open No. 58-13'13'1, which increases fuel during acceleration to supply a rich air-fuel mixture to ensure acceleration response.

[Problems to be Solved by the Invention] By the way, in the above-mentioned engine equipped with two intake passages, one for low load and one for high load, the following problem occurs when the above-mentioned increase in intake during acceleration is performed. .

That is, in a low-load range where the on-off valve that closes the high-load intake passage is closed, the flow rate of air flowing through the low-load intake passage is high, so that fuel vaporization and atomization are good. However, when the above-mentioned valve opens in the high-load range, the flow velocity in the high-load intake passage becomes slow at times during the transient state of the closing time of this valve, and therefore, vaporization and atomization deteriorate, resulting in fuel efficiency. , the emissions will be worse. According to the inventors' research, it takes about 0.3 seconds for the on-off valve to open, and although vaporization and atomization are insufficient during this time, the amount of fuel increases just like when the flow rate is high. The problem lies in the fact that they are allowed to do so.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and its purpose is to propose a fuel control device for an engine equipped with a swirl generation mechanism that improves combustibility during acceleration. It's there.

[Means for solving the problem] As shown in FIG. 1, the configuration of the present invention to achieve the above object includes a low-load intake passage for generating swirl in the engine combustion chamber at low load. In an engine equipped with a high-load intake passage provided with an on-off valve that closes during low load, an increasing means for increasing the amount of fuel during acceleration;
A determining means for determining whether the opening operation timing of the on-off valve coincides with the increase in fuel amount, and a suppressing means for receiving an output of the determining means and suppressing an increase in fuel amount by the increasing means. It is characterized by

[Examples] Examples according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 shows a control system of an embodiment in which the present invention is applied to a fuel control device for a fuel injection type engine. Second
In the figure, the engine body 1 is of a reciprocating type in which a combustion chamber 4 is defined by a piston 3 slidably inserted into a cylinder block 2, and an intake boat 5 opening into the combustion chamber 4 is By the intake valve 6 and also by the exhaust boat 7
are opened and closed by the exhaust valve 8 at known timings.

In the intake passage 9 connected to the intake boat 5, an air cleaner 10, a flap-type air flow meter 11, a throttle valve 12, and a surge tank 13 are disposed in order from the upstream side. The output (Q, ) of the air flow meter 11 is detected by the air flow sensor 21. In the exhaust passage 17 connected to the exhaust boat 7, an air-fuel ratio sensor 18 and a three-way catalyst 19 are arranged in order from the upstream side. This air-fuel ratio sensor 18 is a so-called lean sensor, and its output characteristics continuously change in response to changes in the oxygen concentration in the exhaust gas.

In the example shown in Fig. 2, acceleration detection is performed using the opening angle (α) of the throttle valve 12.
) is detected by the throttle sensor 22, and its time change (
dα/dt) to detect the change in acceleration amount over time. Note that the amount of acceleration may be detected from the amount of depression of an accelerator (not shown).

The intake passage downstream of the surge tank 13 has at least a portion near the intake boat 5 separated by the partition wall 14 into a sub-intake passage 9A having a large effective opening area, and a sub-intake passage 9A having a small effective opening area.
It has a divided structure with a main intake passage 9B oriented in the tangential direction of the combustion chamber 4.

In this auxiliary intake passage 9A, there are shatter valves 1 and 1 in order from the upstream side.
5. A fuel injection valve 16 is disposed, and this shatter valve 15 is configured to close when the shatter valve drive actuator 23 is under a low load, that is, to be fully closed or closed to a slight opening according to a command from the control unit 20.

With this configuration, when the engine is under low load, the shatter valve 15 is closed, so the intake air flows through the main intake passage 9.
Supplied only via B. As a result, the intake air flow rate is increased and sufficient swirl is generated within the combustion chamber 4, thereby ensuring combustion stability at low loads. On the other hand, when the engine is under high load, the shatter valve 15 opens, so that intake air is supplied from the sub-intake passage 9A, which has a large effective opening area. This improves filling efficiency and ensures sufficient output.

FIG. 3 is a detailed block diagram of the control section 20. Each component within the control unit 20 is connected by a bus 35, and the CP
U28 is a microprocessor that performs logical operations and logical judgments required within the control unit 20, and these controls are performed according to a program stored in the ROM 29. The RAM 30 is a memory that temporarily stores various intermediate data required for engine control, and the engine rotation speed counter 31 is connected to the engine rotation speed sensor 29.
It counts the pulses from the engine to obtain the engine rotation speed (N), and also functions to interrupt the CPO 28 by controlling the interwoven control section 32 every time the engine rotates, for example.

The timer 33 is a programmable timer that counts periodic pulses, and when a set count value is reached, the include control unit 32 causes the CPU 28 to increment the timer. The A/D converter 34 converts the outputs of the air flow sensor 21 and throttle sensor 22 into digital values. Further, the output interface 36 drives driver circuits 37 and 39 that drive the shatter valve 15 and the fuel injection valves 16 of each cylinder by a predetermined amount in response to a command from the CPU 28.

The types of interrupts used for engine control in this embodiment are an ignition timing interrupt that is synchronized with the engine speed, an asynchronous injection interrupt that is performed asynchronously to the engine rotation during acceleration, and a point at which the shutter valve 15 changes to the closed state. There is a timer interrupt to measure a certain amount of time. Incidentally, since the above asynchronous injection interrupt is performed asynchronously with the engine rotation, a timer interrupt is used. That is, the timer section 33 has at least two channels: a timer for measuring time intervals for asynchronous injection and a timer for measuring time.

Fuel injection control according to this embodiment will be explained using FIGS. 4 to 6. Fig. 4 shows fuel control for so-called synchronous injection, and Fig. 5 shows control for detecting changes in the opening and closing of the shatter valve 15 and setting a constant width of time (T1) when the change changes from closed to open. FIG. 6 shows so-called asynchronous injection control. The general characteristics of the control in the engine of this embodiment are as follows: (1) Based on the engine speed N, the shutter valve 15 opens in the high speed range and closes in the low speed range.

■: When an acceleration state is detected, a so-called acceleration increase is performed. The amount of acceleration increase is the amount of change in basic fuel injection amount Tp (ΔT
p).

■: Performs asynchronous injection when acceleration is detected.

That is, the acceleration increase is performed in two systems: (1) and (2). What is particularly characteristic of this embodiment is that (2) the state in which the above-mentioned acceleration increase is being carried out, and the
5 changes from closed to open, this acceleration increase amount is reduced for a certain period of time. This decrease in accelerated weight gain is due to ■
It is possible to reduce the acceleration increase amount in (1) or decrease the acceleration increase ff1ffi in (2), but both are possible in this embodiment.

In addition, if 8 is the final fuel injection amount in synchronous injection and the acceleration increase correction coefficient of ■ is CAC, τs ” T p
It is CAc. Then, the CAC normally follows the characteristics shown in Figure 7A.
When the shirt valve 15 changes from closed to open using
A CAc according to the characteristics shown in FIG. 7B is used. On the other hand, in the final fuel injection amount in asynchronous injection, TA is the basic injection amount of asynchronous injection, and C is the correction coefficient of ■ related to asynchronous injection.
Then, τ^=TAXC. Here, the correction coefficient C is normally CI, and when the shutter valve 15 changes from closed to open, C2 (Cm
<CI).

The above CAC, CI, Ca, etc. are generally acceleration increase correction coefficients, but for purposes of explanation, CAC is called "acceleration increase correction coefficient" and C1, Cz are called "asynchronous injection correction coefficients". .

The flowcharts shown in FIGS. 4 to 6 will be explained.

When the crank angle reaches a predetermined phase, interrupt 18 in FIG. 4 is activated. Therefore, in step s2, the intake air amount Q and the engine speed N are read. Here, in addition to these amounts, for example, engine water temperature, etc. may be read in order to perform other correction control of the fuel injection amount.

In step S6, a basic fuel injection amount TP is calculated based on the engine rotation speed N, intake air amount Q1, etc. Note that K is a predetermined constant. In step S8, a change ΔTPK in Tp is calculated. Here, to reduce the influence of noise,
ΔTPK is calculated from the moving average of T. That is, Tp of the past n times is TPI, TP2. ~TPn, the previous T is Tp = ('rPl+'rP2+...ten'rpn)/n, and the current Tp is Tp = (Tpz+Tp3...+Tpn+
Tpn++)/n. Therefore, for ΔTp, ΔT PK= (T Pn*l T p+) / n
It is. When acceleration is detected, the acceleration increase amount (■) is determined by this ΔTp based on FIGS. 7A and 7B.

If an acceleration state is not detected in step SIO, the acceleration increase correction coefficient CAc is set to "l" in step S22. That is, no acceleration increase is performed.

When an acceleration state is detected in step SIO, step SIO
Go to step 12 and check the state of flag COF. This flag is set/reset by the control shown in FIG. 5, and is set to ('r+)1'' for a certain period of time after the shutter valve 15 is about to be opened. If “0”, normal acceleration increase (Figure 7A)
Then, the process advances to step S14. If this flag is "1", the process proceeds to step S16, and an acceleration increase correction coefficient CAC (FIG. 7B) corrected to the decrease side is selected. Comparing Figure 7A and Figure 7B, it is found that the same Δ
CAC in FIG. 7B has a lower value than Tp. That is, the acceleration increase amount at the final fuel injection amount of 8 tends to decrease for a certain period of time after the shatter valve 15 is about to be opened.

FIG. 5 will be explained. This interrupt program is activated by the timer section 33 at regular intervals (for example, 1 m5). In step S30, the engine speed N is read. In step S32, based on this rotational speed N, when the shirtta valve 15 is about to be opened, the shirtta valve 15
The zone is determined as to whether it is in an open area or a closed area. This determination is made based on whether N is larger or smaller than the predetermined rotational speed N0. Of course, the determination may be made based on the rotational speed N and the engine load (Q, /N).

If the zone is such that the shatter valve 15 is closed, the process advances to step S50, and the shatter valve 1 is closed via the driver circuit 37.
Close 5. Then, a flag SCF indicating this is set in step S52.

Further, in step S54, a flag OCF indicating that the shatter valve 15 has changed from a closed state to an open state is reset, and a counter CNTR is cleared.

When it is determined in step S32 that the area is such that the shatter valve 15 should be opened, the shatter valve 15 is opened in step s34. In step S36, the previous shirt valve 1
In order to check the open/closed state of 5, check the flag SCF. May it be closed last time! f (SCF="l"), the process proceeds to step s38, where the SCF is reset and the counter CNTR is set to an initial value. This counter is a down counter, and the above initial value is as follows: If To is the cycle at which this interrupt program is called, and T1 is the time required from when the shutter valve 15 begins to open until the flow velocity through the auxiliary intake passage 9A becomes stable. It is chosen so that T+=initial value×T0. In step S42, a flag CO indicating that the shutter valve 15 has started to open from the closed state is set.
Set F. This flag is set to step S1 in FIG.
2 is referred to above.

If the program shown in FIG. 5 is started before the time T1 has elapsed, and it is determined in step S32 that the shutter valve 15 is in a zone where the shutter valve 15 is previously opened, then the SC
Since F has been reset, the process advances to step 534-5 to step 536=>step S44. Here, it is checked whether the counter has reached "O". Reaching "0" indicates that the T1 time has elapsed.

If this T+ time has not yet elapsed, the counter is decremented by 1 in step S46. On the other hand, if the counter reaches "0", the flag COF is reset in step S48.

Thus, since the flag COF is set while time T1 elapses, the acceleration increase correction coefficient C
For AC, the characteristics shown in FIG. 7B are selected. FIG. 8 shows a process in which the shatter valve 15 changes from closed to open during acceleration and the engine speed N gradually increases.
This is the final fuel injection amount for synchronous injection and is the timing of S.

The characteristics of CAc up to time t1 are those shown in FIG. 7A, but when the shirt starter valve 15 is opened at time t1,
, the characteristics shown in Fig. 7B are selected, and then the characteristics shown in Fig. 7A are selected again.
In order to return to the characteristic shown in the figure, the increase during T1 becomes slower as shown in FIG.

FIG. 6 shows a program for asynchronous injection control, which is started at regular time intervals. When this program is started, it is determined in step S60 whether the vehicle is in an acceleration state. If it is determined that it is not in an acceleration state, it returns as is.

If it is determined that the vehicle is in an acceleration state, a basic fuel injection amount (fixed value) TA for asynchronous injection is set in step S62. In step S64, either the asynchronous injection correction coefficient C+ or Ct is determined according to the flag COF, the final fuel injection amount is calculated in step 866 or step S68, and asynchronous injection is performed in step S70.

In this way, in this embodiment, even in asynchronous injection, when the shutter valve 15 shifts from leap to open, the fuel increase amount is corrected in the decreasing direction.

In this way, by correcting both or one of the acceleration increase correction coefficient and the asynchronous injection correction coefficient, the fixed time (TI) when the shatter valve 15 shifts from closed to open,
Since the amount of fuel increase for acceleration is corrected in the direction of decrease,
Even if vaporization/atomization is insufficient during that time, fuel efficiency/emissions will not deteriorate.

In the above embodiment, a certain period of time after the shatter valve 15 changes from closed to open is used as the correction control for acceleration increase correction. It is also possible to set the correction control period to be from the time when the opening starts until the time when this angle reaches a certain opening degree.

The present invention has particularly significant effects on fuel injection type engines, but is also applicable to carburetor type engines. Further, even if the engine is equipped with a swirl generating mechanism, it is also applicable to an engine of a type in which a valve is provided in the main intake passage 9B, such as in Japanese Patent Application Laid-Open No. 58-23245.

Further, the CPU of the control section can be applied to either a digital computer or an analog computer.

[Effects of the Invention] As explained above, according to the engine fuel control device of the present invention, in an engine equipped with a valve mechanism for swirl generation, the valve mechanism changes from closed to open during acceleration or during acceleration. combustibility is stabilized, fuel efficiency and emissions are improved.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of an embodiment according to the present invention, FIG. 2 is a configuration diagram of a fuel control device according to this embodiment, FIG. 3 is a block diagram of a control section, and FIGS. 4 to 6 7A and 7B are characteristic diagrams of the acceleration increase correction coefficient CAc, and FIG. 8 is a timing chart illustrating the response to acceleration of the embodiment. In the diagram, 1... Engine body, 3... Piston, 4,103
... Combustion chamber, 6... Intake valve, 7... Exhaust valve, 9A
... Sub-intake passage, 9B... Bypass intake passage, 11
...Air flow meter, 12...Throttle valve,
15,100... Shatta valve, 16... Fuel injection valve, 20... Control unit, 21... Air flow sensor,
22...Throttle sensor, 23...Shutter valve drive actuator, 24...Fuel supply path, 28...
CPU, 29...ROM, 30...RAM, 60.
...Accelerator opening sensor. Figure 1 Figure 4 Figure 6

Claims (2)

[Claims] (1) In an engine equipped with a low-load intake passage to generate swirl in the engine combustion chamber during low-load conditions, and a high-load intake passage with an on-off valve that closes during low-load conditions, it is possible to remove fuel during acceleration. an increasing means for metering in an increasing direction; a determining means for determining whether the timing of the opening operation of the on-off valve coincides with the increase in the amount of fuel; 1. A fuel control device for an engine, comprising a suppressing means for suppressing fuel increase. (2) When the determining means determines that the timing of the opening operation and the increase in fuel amount overlap, the suppressing means, for a predetermined period of time,
Claim 1 characterized by continuing the above-mentioned suppression.
A fuel control device for the engine described in paragraph 1.