JPH0533699A - Starting excess fuel injection method of multipoint injection engine - Google Patents

Abstract

PURPOSE:To keep off the discharge of unburned fuel without worsening the extent of startability by detecting the rotation of a camshaft, discriminating two cylinders, whose valve opening timing is specified each, and after either of these two cylinders is discriminated, executing the sequential injection at once. CONSTITUTION:In a multipoint injection engine, A fuel injection valve is installed in an intake manifold corresponding each cylinder, and at the time of starting, a top dead center of a reference cylinder is discriminated and then a necessary amount of fuel is sequentially injected into each cylinder in order. On the other hand, a crank angle sensor makes luminescence out of a photodiode 5 pass through each slip 4 of a disk 2 installed in a camshaft 1 of the engine, receiving it with a photosensor 6, and a crank angle is detected. In this case, among cylinders, twos, detecting the rotation of the camshaft 1 and specified with their valve opening timing, are discriminated. Among these two cylinders, either of them is discriminated, and then sequential injection is executed at once.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting fuel injection method for an MPI (multipoint injection) engine.

[0002]

2. Description of the Related Art In an MPI engine, a fuel injection valve is provided in each intake manifold corresponding to each cylinder. Therefore, at the time of starting, the TDC (top dead center) of the reference cylinder is determined, and then each of them is sequentially processed. A required amount of fuel is injected into the cylinder (sequential injection).

2 and 3 schematically show a crank angle sensor. The reference cylinder is discriminated using this crank angle sensor.

A disc 2 is attached to the rear end of the camshaft 1 of the engine, and the disc 2 has two slits formed concentrically. The slits 3 on the inner peripheral side are formed at 6 positions corresponding to the number of cylinders, and the slits 4 on the outer peripheral side are formed at a total of 4 positions which are long corresponding to the reference cylinder (for example, # 1 cylinder) and other short. ing.

As shown in FIG. 3, a photodiode 5 and a photosensor 6 are provided so as to sandwich the slits 3 and 4.
The light emitted from the photodiode 5 is slits 3, 4
Is intermittently sensed by the photosensor 6 across.
The light detected across the slit 3 is output to the controller as an SGT signal, and the light detected across the slit 4 is output to the controller as an SGC signal. The control device determines the # 1 cylinder based on the SGT signal and the SGC signal and gives a drive command to the fuel injection valve. The slits 3 and 4 are designed to detect light 5 degrees before TDC.

FIG. 4 shows the state of fuel injection at the time of starting.

As shown in the figure, at the start of starting, the starting fuel is injected into all the cylinders, and thereafter, until the # 1 cylinder is discriminated by the SGC signal, 1 / of the starting fuel is supplied to all the cylinders.
Inject a quantity of fuel of 6. After the # 1 cylinder is discriminated by the SGC signal, the starting fuel is injected into the cylinders that are sequentially ignited based on the SGT signal (sequential injection).

As described above, by injecting the fuel at the time of starting, the starting can be started without delay, and the discharge of unburned fuel can be suppressed by the sequential injection.

[0009]

In the conventional starting fuel injection method, in order to reduce the emission of unburned fuel at the time of starting,
Sequential injection is carried out. However, since fuel is ejected to all the cylinders until the # 1 cylinder is discriminated, fuel that does not burn will be injected for the longest two crank revolutions. Therefore, unburned fuel is directly discharged as exhaust gas, which may deteriorate the exhaust gas performance.

[0010]

In the starting fuel injection method for an MPI engine of the present invention to solve the above problems, the valve opening timing is specified by detecting the rotation of a cam shaft among a plurality of cylinders. It is characterized in that two cylinders are discriminated and that sequential injection is performed immediately after discriminating one of the two cylinders.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows signal waveforms for explaining a starting fuel injection method according to an embodiment of the present invention.

Cylinder identification is performed based on the level of the SGC signal at the rising and falling edges of the SGT signal.

The states of the SGC signal and the SGT signal corresponding to each cylinder will be examined. # 1 cylinder: SGT signal rises SGC signal is high (H) level. When the SGT signal falls The SGC signal is at H level. # 2 cylinder: SGT signal rises SGC signal is low (L) level. : When the SGT signal falls, the SGC signal is at H level. # 3 cylinder: SGT signal rises SGC signal is at L level. : When the SGT signal falls, the SGC signal is at L level. # 4 cylinder: SGT signal rises SGC signal is at H level. : When the SGT signal falls, the SGC signal is at L level. # 5 cylinder: SGT signal rises SGC signal is at L level. : When the SGT signal falls, the SGC signal is at H level. # 6 cylinder: SGT signal rises SGC signal is at L level. : When the SGT signal falls, the SGC signal is at L level.

When the SGT signal rises and falls, SG
Only the # 1 cylinder has the C signal at the H level.
Only the # 4 cylinder has the SGC signal at the H level when the T signal rises and the SGC signal at the L level when the SGT signal falls. Therefore, the valve opening timings of the # 1 cylinder and the # 4 cylinder are specified based on the SGT signal and the SGC signal.

In injecting the starting fuel, the # 1 cylinder and the # 1 cylinder
By identifying the four cylinders, the # 1 cylinder and the # 4 cylinder are determined, and after determining the # 1 cylinder or the # 4 cylinder, the sequential injection is immediately started.

In the above-described starting fuel injection method, since the sequential injection is performed immediately after determining not only the # 1 cylinder but also the # 4 cylinder, there is no fear that the startability deteriorates. Further, fuel is not injected until the # 1 cylinder or # 4 cylinder is discriminated, so that unburned fuel is not discharged.

[0017]

The starting fuel injection method for an MPI engine of the present invention discriminates between two cylinders whose valve opening timing is specified, and
Since the sequential injection is performed immediately after one of the two cylinders is discriminated, the unburned fuel can be prevented from being discharged and the engine can be started without deteriorating the startability.

[Brief description of drawings]

FIG. 1 is a signal waveform diagram illustrating a starting fuel injection method according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a crank angle sensor.

FIG. 3 is a schematic configuration diagram of a crank angle sensor.

FIG. 4 is an explanatory view of a fuel injection state at the time of starting.

[Explanation of symbols]

 1 cam shaft 2 disc 3 slit 4 slit 5 photodiode 6 photo sensor

Claims (1)

Claim: What is claimed is: 1. Among a plurality of cylinders, two cylinders whose valve opening timing is specified by detecting rotation of a camshaft are discriminated.
A starting fuel injection method for an MPI engine, wherein sequential injection is performed immediately after one of the two cylinders is discriminated.