JPS6093153A - Fuel shut-off device - Google Patents

Abstract

PURPOSE:To enhance the stability of engine running, in a fuel shut-off device in an automibile internal combustion engine, by providing such an arrangement that the cycle number of fuel injection signals is decreased to one half of the number of engine cylinders upon decelerating running so that fuel supply for one-half of the number of cylinders are restarted to restrain impact upon restart of fuel supply to a minimum value. CONSTITUTION:In a fuel shut-off device for automobile engines, which carries out single fuel injection under electronic control, there are provided one fuel injection valve 6 disposed in an intake-air passage upstream of an intake-air manifold, an air-flowmeter 13, a crank angle sensor 14, a throttle valve switch 17 and a control unit 20. Further, in this device, there are provided a fuel injection control means for controlling the fuel injection valve 6 so that fuel injection with an amount for one engine cylinder is carried out every intake cycle of each cylinder, a releasing rotational speed setting means 29 for setting a rotational speed N2 at which fuel shut-off against a part of engine cylinders is released, between the rotational speed N1 and the shut-off releasing rotational speed N3, a rotational speed range discriminating means 26 for discriminating such a condition that the rotational speed of the engine is in a speed range from N3 to N2 and is upon deceleration, and a partial cylinder release setting means 31 for making the injection cycle number of the injection valve 6 one-half the number of engine cylinders.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an improvement of a fuel cutoff device during deceleration operation in an automobile engine that performs fuel injection under electronic control, particularly single point fuel injection.

(Prior Art) Since the driving force of the engine is no longer needed when a vehicle is decelerating, it is common practice to stop the supply of fuel to reduce fuel consumption during deceleration.

In this case, the deceleration state of the vehicle is detected by the throttle valve switch, which is the state when the throttle valve is fully closed, or when the throttle valve becomes less than a certain opening from fully closed, and when this detection signal is received, the control unit If the engine speed at that time is equal to or higher than the cutoff rotational speed N1, the injection signal to the fuel injector is stopped to shut off the fuel, and the engine speed at the fuel cutoff edge reaches the release rotational speed Nm.
(However, when the temperature drops to Ns < Nl), the stoppage of the injection signal is canceled and fuel injection is restarted (for example, see Japanese Patent Application Laid-Open No. 140542/1983). In addition, the amount of fuel necessary for combustion is injected into all cylinders, so in a four-stroke engine, for example, injection is often performed once per revolution of the crankshaft.

By the way, unlike a multi-point fuel injection system that has a fuel injection valve for each cylinder, a single-point fuel injection system that only has one fuel injection valve in the intake passage upstream of the branch pipe collection part of the intake manifold, Since fuel cutoff and release of fuel cutoff by the fuel injector means fuel cutoff for all cylinders and restart of fuel supply, torque fluctuations are large before and after fuel supply is restarted, and as a result, a shock occurs in the front and rear directions of the vehicle, making it difficult to operate the vehicle. There was a problem that the connections were poor and caused discomfort to the driver.

In addition, in a multi-point fuel injection system that includes a fuel injection valve for each cylinder, a control circuit is provided for each of the two injection valve groups, and some cylinders whose engine speed is set between N1 and N3 When the fuel cutoff release rotation speed drops below N2, the stoppage of the injection signal to one of the injector groups is canceled to prevent vehicle impact and rotation speed drop due to torque fluctuations before and after resuming fuel supply. However, in this case, compared to a single-point fuel injection system, the number of injection valves is large, and the fuel piping and control circuit (1111) are extremely complicated, resulting in poor productivity and high costs.

(Object of the Invention) The present invention outputs an injection signal to the injection valve for each intake stroke of each cylinder, and after the fuel is cut off, the engine speed is reduced to N2 (N
! <N2 <Nl), the number of injection signals is reduced to half the number of cylinders and fuel supply to half the cylinders is resumed, thereby minimizing the shock to the vehicle due to sudden torque fluctuations when fuel supply is resumed. Designed to improve driveability by suppressing
Furthermore, it is an object of the present invention to provide a fuel cutoff device that achieves the same effect as a multipoint fuel injection system even in a single point fuel injection system, simplifies piping and control circuits, and improves productivity and controllability. With the goal.

3- (Structure and operation of the invention) FIG. 1 is an overall block diagram for clearly showing the structure of the present invention.

That is, the present invention includes one fuel injection valve 6 interposed in the intake passage 4 flowing from the branch pipe collecting portion 3 of the intake manifold 2, an air flow meter 13 for detecting the amount of intake air,
A crank angle sensor 14 that detects the engine speed and a throttle valve 5
The throttle valve switch 17 detects the fully closed position of the engine, outputs a predetermined fuel injection signal based on the intake air amount and engine speed, and when the engine decelerates, the engine speed changes to the cut-off speed N1.
The present invention is based on a fuel cutoff device including a control unit 20 which cuts off the injection signal when the rotational speed is higher than N1 and supplies the injection signal again when the cutoff release rotational speed N3 is lower than N1.

Further, the present invention provides this device with a fuel injection control means 28 that controls the injection valve 6 to inject fuel for one cylinder every intake stroke of each cylinder, and a fuel injection control means 28 between the N1 and N3. a release rotation speed setting means 29 for setting the rotation speed N2 at which the fuel cutoff of the first cylinder is canceled; Based on the discrimination means 26 and the discrimination result, the engine speed is determined in the rotation range from N to N2.Therefore, fuel is supplied in accordance with the intake stroke of the common cylinder.
It is possible to control the fuel supply to each cylinder while using single-point fuel injection, so if the number of injections is further controlled, fuel supply and fuel cut-off to a specific cylinder can be controlled.

(Embodiment) FIG. 2(A) is a schematic 11r7 configuration diagram of an embodiment of the present invention, which is applied to a four-cylinder engine. However, Figure 2B
) is a partial plan view of FIG.
An intake passage 4 upstream of the branch pipe collection part 3 of the intake manifold 2 (for example, since the throttle valve 5 is installed immediately upstream of the branch pipe collection part 3, the intake passage further upstream of the throttle valve 5) , the fuel pumped by the fuel pump in the fuel supply system is supplied to the intake air flowing in through the air cleaner 11. 8 is a fuel filter, 9 is a fuel tank, and 10 is a pressure X component. It is.

20 is a control unit that controls the fuel injection amount and injection timing, and is mainly a microprocessor (central processing unit).
, a memory (storage device), and an interface (input/output signal processing circuit), which detects the signal from the air flow meter 13 that detects the intake air amount Q, the engine speed N, and the crank angle that detects the reference position of the crank angle. Angle sensor 14
unit crank angle pulse and crank angle reference Hals from, a signal from the water temperature sensor 15 that detects the engine cooling water temperature,
A signal from the oxygen concentration sensor 16 that detects the oxygen concentration in the exhaust gas and a signal from the throttle valve switch 17 that detects when the throttle valve 5 is fully closed (or below a predetermined small opening) are input, and these signals are Basically, a fuel injection signal is generated which is synchronized with the engine rotation and has a pulse width corresponding to the amount of intake air, and the fuel injection valve 6 is driven by this signal.

At the same time, the control unit 20 switches the throttle valve switch 1
7 and the rotational speed signal from the crank angle sensor 14, the fuel is cut off during deceleration. This will be explained based on the block diagram of the control unit 20 in FIG.

21 is deceleration detecting means which inputs the signal from the throttle valve switch 17, and when the throttle valve switch 17 is ON (throttle valve 5
(in the fully closed state), it is detected that deceleration is occurring.

Reference numeral 22 denotes a rotation speed detection means, which detects the unit angle/solus (rotation speed signal) from the crank angle sensor 14 that occurs during a certain period of time.
is expressed as H4, and this value is output as a signal indicating the engine speed N.

Reference numeral 24 denotes a cutoff rotational speed setting means for setting the rotational speed at which fuel cutoff is performed, and the cutoff rotational speed N is set in advance according to the engine water temperature (detected by the engine water temperature detection means 23). (see), read N1 at that time.

Reference numeral 25 denotes a release rotation speed setting means for setting the rotation speed at which the fuel cutoff is canceled, and similarly, the release rotation speed is determined from a map (see Fig. 4) of the release rotation speed Na (however, Ns < Nl), which is preset according to the engine water temperature. Read out Ns at that time.

7- When the deceleration detection means 21 detects deceleration, the rotation range determination means 26 compares the engine rotation speed N and the set rotation speed N, , N, and determines the rotation range in which the fuel is cut off.

The all-cylinder cutoff setting means 30 and the all-cylinder release setting means 32 set a fuel cutoff coefficient α (1 during normal fuel injection and 0 during fuel cutoff).
are respectively set based on the determination result of the determining means 260.

Specifically, when N is decelerating from Ns (for example, 1600 rpm) or more, α is set to 0 in the all cylinder cutoff setting means 30, and when it decreases to Na (for example, 11000 rpm), α is set to 0 in the all cylinder cutoff setting means 32. Then α is set to 1 again (therefore, α is not set to 0 when decelerating from a rotational speed where N is much lower than N1).

The fuel injection control means 28 calculates the basic injection/main pulse width T, which is calculated from the intake air amount Q (detected by the intake air amount detection means 27) and the engine speed N, (= -Q/Nfc and K
is a constant), the correction coefficient Kiri obtained from other driving norm meters, and the above-mentioned α are multiplied to determine the normal injection 9-rus width T.
An injection pulse (injection signal) with an injection pulse width of 8- is supplied to the fuel injection valve 6 so that i=Tp- and α.

Therefore, since α-1 during normal fuel injection, the injection valve 6 is opened for a time corresponding to the value of Ti (='['p-, ), and fuel proportional to this valve opening time is injected. However, if α=O based on the determination of the cut-off rotation range, 'ri=o, and no drive pulse is output.

That is, if a deceleration state is determined and the engine speed N at that time is greater than or equal to Ns (for example, 1600 rpm), fuel is cut off for all cylinders, and the engine speed is increased to Ns (for example, 100 rpm).
0 rpm) i, fuel injection in all cylinders is restarted (therefore, if N is smaller than N1, fuel cutoff is not performed).

The following configuration is the same as the conventional one, but in the present invention, it additionally includes a fuel injection control means 28, a release rotation speed setting means 29, and a rotation range determination means 26.

A partial cylinder release setting means 31 is provided.

The release rotation speed setting means 29 sets the rotation speed N2 (Nl >N2 >N) at which fuel cutoff of some cylinders is canceled between N and N.
3), the current N2 is determined from the map (Fig. 4) of the cut-off rotation speed N2, which is preset according to the engine water temperature.
Read out.

The fuel injection control means 28 has a function of calculating the injection pulse width Ti described above, and a function of controlling the fuel injection timing.The fuel injection control means 28 has a function of calculating the injection pulse width Ti described above, and a function of controlling the fuel injection timing. The injection valve 6 opens to perform injection.

The rotation range determining means 26 also has the function of the present invention added to the conventional function, and determines whether N is in the rotation range from N3 to N2 and the vehicle is decelerating.

Based on this determination result, the partial cylinder release setting means 31 sets the above-mentioned α so that the number of injections from the control p means 2B is half the number of cylinders.

Specifically, α is alternately set to 1 and 0 so that one injection is performed per engine revolution.

Next, the operation will be explained based on the flowchart of FIG. Note that P1 to l''+2 in the figure indicate each step, and control calculations are executed in synchronization with engine rotation.

When the engine is running normally, the throttle valve switch 17 is not ON at P, so the shutoff coefficient α is 1 at pH, and the injection nozzle width Ti is Tp-KI (starting TpU intake air amount Q and engine The basic pulse width calculated from the rotational speed N is a correction coefficient based on the operating parameters), and the injection valve 6 is driven to open and close using this injection pulse width. In this case, the injection timing is set according to the intake air of each cylinder. This is done for each step. In other words, when the intake valve is opened by a predetermined rank angle, the injection valve 6 is opened, the injected fuel passes through the throttle valve 5, diffuses into the intake manifold 2, and then the intake valve is opened. is supplied to the cylinder.

Now, the ignition order of a 4-cylinder engine is 41=1→3−≠4−≠2
As shown in Figure 6, the injection timing of the injector 6 is shown. Injection is performed every intake stroke of each cylinder, and regardless of single-point fuel injection, it corresponds to sequential injection, which is a method of multi-point fuel injection. This results in the effect of

Next, the engine speed N is N+ (for example, 1600 rpm
) Release the accelerator pedal from the high rotation range above to decelerate by 1.
1- When done, the throttle valve switch 17 turns ON (throttle valve 5 closes) and N≧N, so α is OK at P9.
Set.

Therefore, when Ti=0 at P8, no drive pulse is output and fuel is cut off for all cylinders.

Due to this all-cylinder fuel cutoff, the engine speed N decreases, and N2
> When N≧N3, α is alternately set to 0 and 1 for each ignition in Plo.

In other words, the fuel cutoff is canceled once per engine revolution (
+1 according to the ignition order (injected at half the normal number of injections). If only the injection corresponding to the intake stroke of the ≠4 cylinders is restarted, most of the injected solvent will be taken into the 11.44 cylinders and partial cylinder combustion will occur, as shown in FIG. Therefore, torque is generated once per engine revolution.

In this case, a very small amount of injected fuel is supplied to cylinders other than the receiver cylinder during the intake stroke due to intake pulsation and interference.
It does not have a negative effect on the catalyst in the exhaust passage.

When the deceleration state is maintained and N becomes Ns (for example, 12-1000 rpm) VC at P8, α is set to 1 again at PIIK, and injection is performed twice per engine revolution, so that all cylinders are injected with fuel. Normal fuel injection takes place with the supply resumed.

Therefore, a partial cylinder cut-off rotation speed range A (Fig. 4) is formed between the all-cylinder fuel cut-off rotation speed N1 and the all-cylinder cut-off release rotation speed N3, and when recovering from the fuel cut-off, - Instead of restarting fuel supply to all cylinders at once, fuel supply is always restarted to half of the cylinders, which alleviates torque fluctuations before and after refueling and minimizes shock to the vehicle. .

Furthermore, since the single stroke position of the injection valve 6 is far away from the intake port, it is necessary to consider the behavior of the injected fuel in relation to the opening time of the intake valve. FIG. 8 shows the opening time of the intake valve.

Partial cylinder injection release rotation range A (1000 to 1500 r
pm), the injection nozzle width i'i (opening time of the injection valve, for example, about 1.2 m5ec at 120Orpm)
On the other hand, the opening time T of the intake valve suddenly increases (for example, 12.5 m5ec at 240Orpm becomes 120Orpm).
25 m5ec).

On the other hand, the passage distance between the injection valve 6 and the intake valve is approximately 0.3 m.
Aυ, since vaporized fuel flows at the speed of sound during deceleration, the time required for the fuel vaporized immediately by injection to reach the opening of the intake valve is approximately 1 m5ec. The time Tj (dashed line in Fig. 8) required for the same to reach the opening is approximately IQ m5ec.
These required times are defined as the injection valve opening time T
Even if added to i, it is still sufficiently small compared to the opening time T of the intake valve. Therefore, most of the calculated amount of fuel is supplied to some cylinders, and the combustion state is maintained in good condition. Therefore, even if the injection valve 6 is installed at a remote location, part 1 (cylinder cutoff release rotation range A (1000
~1500 rpm) can be easily set.

Alternatively, the throttle valve switch 17 may be replaced with a negative pressure sensor that detects the suction negative pressure downstream of the throttle valve 5, and in this case, the deceleration state will be detected by the suction negative pressure.

Also, release of fuel cutoff for some cylinders is +3. It may be done for +2 cylinders, or if uniform torque fluctuation is not required, =ll-11+-2 cylinders or +-3, +1
It is also possible to release fuel cut-off for one of the cylinders.

(Effects of the Invention) As described above, according to the present invention, fuel is injected by the single-point fuel injection valve every intake stroke of each cylinder, and the fuel cut-off rotation speed N during deceleration and the fuel cut-off release rotation speed N are , the partial cylinder cutoff release rotation speed N2 is set between N2 and N3, and the partial cylinder cutoff release rotation speed range is set between N2 and N3. Since the fuel supply to half of the cylinders is restarted before the solvent supply to the cylinders is restarted, torque fluctuations are alleviated and the sudden torque fluctuations before and after fuel supply restarts do not occur as in the conventional case. This has the effect of significantly improving drivability.

Since the same effect as the one-minute cylinder cut-off release performed by the known multi-point fuel injection system is performed by the present invention, the piping and control circuits are incomparably different from this multi-point fuel injection system. can be simplified,
It also has the effect of improving productivity and controllability.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the present invention. Figure 2) is an overall view of one embodiment of the present invention, Figure 20 is a partial plan view of Figure 2 (5), and Figure 3 is a block diagram of the control unit in Figure 2 (5). be. Fig. 4 is a characteristic diagram of the set rotation speed with respect to engine water temperature, Fig. 5 is a flowchart showing the arithmetic processing of the control unit in Fig. 2 (5), Fig. 6 is a diagram explaining the fuel injection timing in normal conditions, Fig. 7 is a diagram explaining the fuel injection timing when fuel cutoff is released for some cylinders, and Fig. 8 shows the intake valve opening time, injection valve opening time, and time required by wall fuel flow with respect to engine speed, respectively. It is a characteristic diagram. 2. Intake manifold, 3. Branch pipe collection, 4.
Suction passage, 5... Throttle valve, 6... Fuel injection valve, 13.
...Air flow meter, 14...Crank angle sensor,
17... Throttle valve switch, 20... Control unit, 16-21... Deceleration detection means, 22... Rotation speed detection means, 24... Cutoff rotation speed setting means, 25.29... - Release rotation speed setting means, 26...What E11 reprinting determining means, 2
7... Intake air amount detection means, 28... Fuel injection control means, 3061. All cylinder shutoff 1 ton r setting means, 31...
・Partial cylinder disassembly! , 1'-, setting means, 32... all cylinder release setting means. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Scope of Claims] One fuel injection valve installed in the intake passage upstream of the branch pipe collection part of the intake manifold, an air 70-meter for detecting the amount of intake air, and a crank for detecting the engine speed. An angle sensor, a throttle valve switch that detects the fully closed position of the throttle valve, outputs a predetermined fuel injection signal based on the intake air amount and engine speed, and when the engine decelerates, the engine speed changes to the cutoff speed N. . In the fuel cutoff device, the fuel cutoff device includes a control unit that cuts off the injection signal when the rotational speed is higher than N1 and supplies the injection signal again when the cutoff release rotation speed N3 is lower than N1. a fuel injection control means for injecting fuel for one cylinder;
Between 1 and N, the rotation speed N at which the fuel cutoff of the first cylinder is released.
a release rotation speed setting means for setting the engine rotation speed; a rotation range determination means for determining that the engine rotation speed is in the rotation range from N8 to N2 and during deceleration; A fuel cutoff device characterized in that a partial cylinder release setting means is provided which reduces the number of injections of the injection valve to half the number of cylinders when the engine speed reaches the N2 rotation range.