JPS59213930A - Electronic control fuel injector for internal-combustion engine - Google Patents

Abstract

PURPOSE:To stabilize the engine rotation by setting the recovery rotation in accordance with the load condition decided through detection of deceleration speed when fuel is cut. CONSTITUTION:The engine deceleration due to decelerating operation is detected by a load decision circuit 7. Said circuit 7 will detect the decelerated engine speed and decide a loaded or unloaded condition from the inclination of variation. The recovery rotational number of fuel cut circuit is set in accordance with the load condition. Consequently the engine speed can be stabilized.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and in particular, measures to improve fuel efficiency in a device of the type that stops fuel injection during deceleration and resumes fuel injection when the rotation speed falls below a set rotation speed. Regarding.

<Prior art> Conventional electronically controlled fuel injection systems for internal combustion engines generally measure the intake air flow rate detected by an intake air flow rate measuring device (air 70 meter) and the engine speed detected from the ignition signal of the ignition coil. Determine the basic injection amount, correct this as appropriate to obtain the injection amount, and drive the electromagnetic fuel injection valve at a predetermined timing once per engine rotation using an injection pulse TiK with a pulse width based on this. , inject and supply the optimum amount of fuel to the engine.

During deceleration, this is detected using an idle switch that turns on when the throttle valve is fully closed (idle state), and at this time, fuel injection is stopped (fuel cut) to improve fuel efficiency and reduce engine speed. Fuel injection was restarted (recovered) when the number of revolutions decreased to below a predetermined number of revolutions.

However, in conventional electronically controlled fuel injection systems, the engine speed at which fuel injection is resumed during deceleration (hereinafter referred to as recovery speed) is set regardless of the engine load condition, which causes the following problems. there were.

In other words, when decelerating under a load such as when driving, the rotational inertia is large, so the engine rotational speed is gradually reduced, and the recovery rotational speed is therefore reduced to a small value as shown in Figure 1 (A). Even if the engine speed is set to N3, the engine speed will not drop too much, but when decelerating in a no-load operating state, the inertia is small, so the deceleration speed will be large.If the recovery speed is set to a small value N3, the first As shown in Figure (B), the engine quoting number decreases too much and it finally stops.

Therefore, in order to ensure a stable rotation speed even during deceleration during no-load operation, the recovery rotation speed is set to N! [N2 (Nl>N2 >N3
), the undershoot is large and unstable], and if this is done, the fuel cut time during deceleration under load operation will be shortened, making it impossible to obtain a sufficient fuel consumption reduction effect.

<Purpose of the Invention> The present invention was made in view of these conventional problems, and by changing the recovery rotation speed according to the deceleration speed during deceleration, the present invention can be used during deceleration regardless of no load, load, or load operation. An object of the present invention is to provide an electronically controlled fuel injection device for an internal combustion engine that can improve fuel efficiency by increasing fuel cut time as much as possible while ensuring stable rotation after recovery.

<Structure of the Invention> For this reason, the present invention includes means for determining the engine load condition by detecting the deceleration speed during deceleration operation when fuel is cut, and for determining the recovery rotation speed according to the valve load condition determined by the means. The configuration includes a means for setting.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 2 showing one embodiment, the ignition signal (rotation pulse) of the ignition coil 1 and the output signal of the intake air flow rate measuring device (air flow meter) 2 are input to the basic pulse generation circuit 3. There is.

A fuel cut circuit 4 is connected to the skewer end of the basic pulse generating circuit 3. A rotation pulse is input from the ignition coil 1 to the fuel cut 4, and output terminals of an idle switch 5, a water temperature sensor 6, and a load determination circuit 7 are connected to the fuel cut 4. The idle switch 5 is a switch that is turned on when a throttle valve (not shown) is fully open, and the water temperature sensor 6 is a sensor that generates an output in accordance with the engine cooling water temperature.
During deceleration, the load determination circuit detects the deceleration of the engine speed and determines that there is no load when θ=jan-1N/l is θ≦θO as shown in FIG. θ〉θ0
When this happens, it is determined that there is a load condition and this 141 constant signal is output.

A drive circuit 8 is connected to the output end of the fuel cut circuit 4, and an electromagnetic fuel injection valve 9 is connected to the output end of the drive circuit 8.

Thus, the rotation pulse corresponding to the engine speed N from the ignition coil 1 and the output voltage (U/
Ub: the reciprocal of the intake air flow rate), the basic pulse generation circuit 3 calculates the basic injection amount (Q/N) and generates a basic pulse corresponding to this. The fuel cut circuit 4 is operated by a rotation pulse when the engine rotation speed is a predetermined rotation speed (for example, 1640 rpm).
m) If the above is true, and the idle switch 5 is on, and the water temperature detected by the water temperature sensor 6 is above a predetermined value, a basic pulse is sent to the drive circuit 8 to stop the fuel supply to the engine. Block passage.

On the other hand, due to such deceleration operation, the deceleration speed of the engine rotational speed is detected by the load determination circuit t as described above. When the deceleration speed is equal to or higher than a predetermined value and it is determined that there is no load, the fuel cut circuit 4 to which this determination signal is input will respond when the engine speed corresponds to the no-load operation state or becomes lower than the cover rotation speed N1. Even if the idle switch 5 is in the ON state, the basic pulse is sent to the drive circuit 8 in order to supply fuel again.
pass to. The basic pulse that has passed through the fuel cut circuit 4 becomes a fuel injection pulse, and the drive circuit 8 and fuel injection valve 9 are driven in accordance with this fuel injection pulse.

Further, when the deceleration speed detected by the load determination circuit 4 is lower than a predetermined value and it is determined that the load operation state is in progress, the fuel cut circuit to which this signal is inputted determines that the engine speed is N+
When the recovery rotation speed is lower than the very small recovery rotation speed N3, a basic pulse is passed through the drive circuit 8 to drive the fuel injection valve 9.

In this way, when decelerating during no-load operation, the engine rotation speed is increased by increasing the engine rotation speed, and by reducing the beam cover rotation speed during load operation, the fuel cut time is extended and fuel efficiency is improved. It is.

In this embodiment, the recovery rotation speed is changed in two stages: no-load operation and loaded operation, but the recovery rotation speed may be continuously decreased as the load increases.

<Effects of the Invention> As explained above, according to the present invention, the recovery rotation speed is set according to the load condition determined by detecting the deceleration speed when the engine is decelerated due to fuel cut. The effect is that fuel efficiency can be improved by increasing the fuel cut time as much as possible while keeping the number stable.

[Brief explanation of the drawing]

Figure 1 (A) is a diagram showing the change in engine speed when the recovery speed is changed under load operation, and Figure 1 (B) is a diagram showing the engine speed when the recovery speed is changed under no-load operation. Fig. 2 is a control block diagram showing an embodiment of the present invention; Fig. 3 is a diagram showing a deceleration speed detection method according to the above embodiment; Fig. 4 is a diagram showing the deceleration speed detection method according to the above embodiment. FIG. 1... Ignition coil 2... Intake air flow rate measuring device 3
... Basic pulse generation circuit 4 ... Fuel cut circuit 5 ... Idle switch 6 ... Water temperature sensor
7...Load judgment circuit 8...Drive circuit 9...
・Fuel injection valve patent Applicant Fujio Sasashima, Patent Attorney, Japan Electronics Co., Ltd. Figure 1 (

Claims (1)

[Claims] The fuel injection amount is calculated based on the intake air flow rate and the engine speed, and the fuel injection valve is driven by the corresponding injection pulse to inject fuel, while the fuel injection is stopped during deceleration.
In an electronically controlled fuel injection system for an internal combustion engine, which restarts fuel injection when the rotational speed drops below a preset rotational speed during a stop, the engine load condition is determined by detecting the deceleration speed of the engine rotational speed during deceleration. An electronically controlled fuel injection system for an internal combustion engine, characterized in that it is provided with means for determining, and means for setting an engine speed at which fuel injection is restarted in accordance with the load condition determined by the load determining means.