JP2917183B2 - Start control device for fuel injection device of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a start control device for a fuel injection device of an internal combustion engine, and more particularly to a device capable of improving fuel injection control at the time of start to improve startability.

[0002]

2. Description of the Related Art As a fuel injection device for an internal combustion engine, an injection pulse width proportional to a fuel injection amount is set on the basis of an intake air flow rate Q of the engine and an engine rotation speed Ne. There has been known an apparatus configured to output an injection pulse signal having the injection pulse width to a fuel injection valve.

When the engine is started, the detection accuracy of the intake air flow rate Q by the air flow meter is significantly deteriorated by the occurrence of a large pulsation, so that the injection pulse width is calculated to a value completely different from the required amount. There is fear. Therefore, conventionally, in the starting state of the engine, a signal of the injection pulse width at the start which is set in advance corresponding to the cooling water temperature representing the engine temperature is output to the fuel injection valve in synchronization with the engine rotation. (Japanese Unexamined Patent Publication No.
-60737).

[0004]

However, when analyzing the fuel supply process at the start, it is not that the air-fuel mixture having the required air-fuel ratio is supplied into the combustion chamber immediately after the start of the injection and explodes. After the amount of wall adhesion (wall flow) reaches a predetermined amount that varies depending on the manifold shape and the wall temperature at that time, the fuel flows into the combustion chamber, forms the required mixing ratio, and explodes. follow.

The starting injection pulse width set based on the cooling water temperature is set such that the required mixing ratio is formed in a state where the wall flow is satisfied. The injection is exclusively used to satisfy the wall flow, and the startup is delayed by the time until the wall flow is satisfied, and the exhaust characteristics deteriorate during this time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and shortens the time from the start of the start to the complete explosion by filling the wall flow in a short time after the start of the fuel injection at the start. And at the same time, improve the exhaust characteristics at the time of starting.

[0007]

Therefore, a starting control device in a fuel injection device for an internal combustion engine according to the present invention is shown in FIG.
It is configured as shown in FIG. In FIG. 1, the injection control means sets an injection pulse width corresponding to the intake air amount of the engine, and outputs an injection pulse signal of the injection pulse width to the fuel injection valve at a predetermined timing synchronized with the engine rotation. .

[0008] In contrast, starting asynchronous injection control means, in a fixed starting control time from the detection of the start of the engine starting by the starter start detecting means, instead of the prior Ki噴 morphism control means, predetermined injection An injection pulse signal having a predetermined start injection pulse width is output to the fuel injection valve every interval time.
The injection interval time setting means sets the injection interval time shorter as the engine temperature detected by the engine temperature detection means is lower.

[0009]

According to this configuration, an injection pulse signal having a predetermined start injection pulse width is output to the fuel injection valve at predetermined injection intervals within a fixed start control time after the start of the engine. . Therefore, even if the start-up injection pulse width is matched to the required amount after the wall flow is satisfied, the rotation of the engine is reduced by injecting and supplying the fuel at predetermined intervals without correlation with the intake stroke of the engine. It is possible to satisfy the wall flow early without waiting. Further, by changing the injection interval time to be shorter as the engine temperature is lower, the fuel can be injected and supplied according to the difference in the wall flow filling amount due to the engine temperature.

[0010]

Embodiments of the present invention will be described below. In FIG. 2 showing one embodiment, air is sucked into an internal combustion engine 1 from an air cleaner 2 through an intake duct 3, a throttle valve 4 and an intake manifold 5. In each branch of the intake manifold 5, a fuel injection valve 6 is provided for each cylinder. The fuel injection valve 6 is an electromagnetic fuel injection valve that is energized by a solenoid and opens, and is deenergized and closed by being energized by an injection pulse signal from a control unit 12 described later. , Which intermittently injects fuel supplied from a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator to the engine 1. The amount of injected fuel is adjusted by the pulse width of the injection pulse signal. It has become.

Each combustion chamber of the engine 1 is provided with an ignition plug 7, which ignites a spark to ignite and burn an air-fuel mixture. Then, exhaust gas is discharged from the engine 1 through the exhaust manifold 8, the exhaust duct 9, the catalyst 10, and the muffler 11. The control unit 12 includes a CPU, ROM, R
A microcomputer including an AM, an A / D converter, an input / output interface, and the like is provided. The microcomputer receives input signals from various sensors, performs arithmetic processing as described later, and controls the operation of the fuel injection valve 6. I do.

The various sensors include an intake duct 3
An air flow meter 13 is provided therein, and outputs a signal corresponding to the intake air flow rate Q of the engine 1. Further, a crank angle sensor 14 is provided, and a reference angle signal REF for each reference angle position (every 180 ° CA in a four-cylinder engine) and 1 °
Alternatively, a unit angle signal POS for every 2 ° is output. Here, the engine rotation speed Ne can be calculated by measuring the period of the reference angle signal REF or the number of occurrences of the unit angle signal POS within a predetermined time.

Further, a water temperature sensor 15 (engine temperature detecting means) for detecting a cooling water temperature Tw (a parameter representing the engine temperature) of the water jacket of the engine 1 is provided. Note that, instead of the water temperature sensor 15, a sensor for detecting the wall temperature of the intake manifold 5 (the temperature of the portion where the fuel spray adheres by the fuel injection valve 6) may be provided.
Further, an on / off signal of a starter switch 16 for controlling on / off of a starter motor (not shown) is input to the control unit 12.

Here, the CPU of the microcomputer built in the control unit 12 performs arithmetic processing according to the program on the ROM shown in the flowchart of FIG. 3 to control the fuel injection to the engine 1. In this embodiment, the control unit 12 has software functions for the functions of the start-time asynchronous injection control means, injection control means , and injection interval time setting means, as shown in the flowchart of FIG. Further, in the present embodiment, the start of the engine is detected based on the on / off of the starter switch 16, so that the starter switch 16 corresponds to the start start detecting means.

In the program shown in the flowchart of FIG. 3, first, step 1 (S1 in the figure).
In the following, it is determined whether or not the starter switch 16 has been switched from OFF to ON. If the starter switch 16 is switched from OFF to ON, it means that the starter motor has been started and the start of the engine 1 has been started. Therefore, the process proceeds to step 2 to measure the elapsed time _Xt1 from the start of the start. Start the _Xt1 timer of

On the other hand, if it is not determined in step 1 that the starter switch 16 has been switched from OFF to ON, step 2 is jumped to step 3. Step 3
Then, for example, it is determined whether or not the engine 1 is rotating based on whether or not a rotation signal is output from the crank angle sensor 14. When the engine 1 is not rotating,
This program is terminated without performing fuel injection.

When the engine 1 is rotating, the process proceeds to step 4, where it is determined whether or not the time measured by the _Xt1 timer started in step 2 exceeds a predetermined time _Xt1, and a predetermined time from the start of the start is determined. It is determined whether it is within the start control period. The predetermined time _Xt1 is a fixed value.

Here, if it is determined that it is within a predetermined period (within a predetermined start control period) from the start of the start of the engine 1, the routine proceeds to step 5 to execute the fuel injection control for starting. In step 5, with reference to a map in advance of the cooling water temperature Tw injector during startup is set according to the pulse width X _t3 and the injection interval time by the start-time injection pulse width X _t3 X _t2, current of the cooling water set by searching the starting injection pulse width X _t3 and the injection interval time X _t2 corresponding to the temperature Tw.

In the next step 6, it is determined whether or not the injection interval time _Xt2 has elapsed.
Each _{time t2} has elapsed, the process proceeds to the next step 7, the start-time injection pulse width X _t3, is set to the pulse width Ti of the injection pulse signal sent to the fuel injection valves 6, the next step 8, the The injection pulse signal having the pulse width Ti is supplied to the fuel injection valve 6.
And the fuel equivalent to the start-time injection pulse width _Xt3 is injected and supplied from the fuel injection valve 6 every injection interval time _Xt2 (see FIG. 4).

Therefore, according to the above control, during the predetermined period from the start of the start of the engine 1, the fuel injection is performed every predetermined time _Xt2 , so that the injection pulse width _Xt3 is required in the injection control synchronized with the rotation. Even if it is matched to the mixture ratio formation, more fuel than the amount required for the required mixture ratio formation is injected and supplied in a short period of time, shortening the time from the start of starting until the wall flow is satisfied it can.

That is, at the time of starting, first, after a predetermined wall adhesion amount (wall flow) is satisfied, fuel flows into the combustion chamber to form a required mixing ratio. In the injection supply configuration, the wall flow needs a predetermined number of engine rotations to satisfy the wall flow, and the filling completion time changes due to a change in the start-up rotation speed by the starter motor until the wall flow is satisfied. Causes the starter motor to be rotated uselessly.

Therefore, in contrast to the normal injection performed in synchronization with the rotation, the fuel injection is performed every predetermined time _Xt2 (as time synchronization) within a predetermined period from the start, so that the injection control in the normal rotation of the engine is performed. In this configuration, the number of additional injections is secured more than the number of injections per rotation in, so that the wall flow can be satisfied with time as a parameter.
By changing the injection pulse width _Xt3 and the injection interval time _{Xt2 according} to the change in the wall flow filling amount that changes with the engine temperature, the wall flow can be stably filled in a short time, and the required mixing ratio The start of formation of the motor in a short time can be realized by avoiding useless cranking rotation.

As shown in the flow chart of FIG. 3, in the present embodiment, the starting pulse width _Xt3 is hardly changed with respect to the change of the cooling water temperature Tw.
_{When the} cooling water temperature Tw is low and the cooling water temperature Tw is low and the wall flow is full, the number of injections per unit time is increased to complete the wall flow in a short time. It is way. Incidentally, the injection interval time X _t2 to short that when the coolant temperature Tw is low, and the injection pulse width X _t3
May be set longer as the cooling water temperature Tw is lower.

By the way, the injection interval time X _t2 and start-time injection pulse width X _t3, in addition to variably set in accordance with the coolant temperature Tw representing the engine temperature as described above, cold
The engine speed Ne is variably set as a parameter together with the cooling water temperature, and the fuel is injected with a larger pulse width or / and at shorter intervals as the engine speed Ne becomes lower, When the wall flow is satisfied and an explosion occurs, the fuel may be injected substantially in the same manner as the rotation-synchronous start-up fuel control.

[0025] Also, Content amount before Kikaberyu, since changes according to the temperature of the wall surface which injected fuel in the intake manifold is attached, in place of the coolant temperature Tw, so as to detect the wall surface temperature directly May be.

If it is determined in step 4 that a predetermined period has elapsed since the start of the fuel injection and supply in a time-synchronous manner as described above, the process proceeds to step 9 where the cylinder intake air amount is adjusted in synchronization with the engine rotation. The process shifts to the normal control for injecting and supplying the appropriate fuel. Specifically, the air flow meter 13
A basic injection pulse width Tp corresponding to the cylinder intake air amount is calculated from the intake air flow rate Q and the engine rotational speed Ne detected in the step (a) to obtain a predetermined mixing ratio. Set the correction coefficient CO, and
A voltage correction amount or the like for correcting a change in the effective injection time of the fuel injection valve 6 due to a change in the battery voltage is set, and the result of correcting the basic injection pulse width Tp by the various correction terms is a final injection pulse width. Ti is set, and an injection pulse signal having the injection pulse width Ti is output to the fuel injection valve 6 at a predetermined timing synchronized with the engine rotation.
Here, in the rotation-synchronous injection control, either sequential injection injection in which injection is performed in accordance with the intake stroke of each cylinder or simultaneous injection of all cylinders may be used.

In this embodiment, the fuel injection valve 6 is provided for each cylinder. However, for example, only one fuel injection valve is provided on the upstream side of the throttle valve 4, and the fuel is supplied from the fuel injection valve. A configuration in which fuel is distributed to each cylinder may be adopted. Further, in the present embodiment, the air flow meter 13 is provided, but a negative pressure sensor for detecting the suction negative pressure is provided instead of the air flow meter 13, and the suction negative pressure detected by the negative pressure sensor and the engine speed The basic injection pulse width Tp may be set based on Ne. Further, the basic injection pulse width Tp may be set based on the opening degree of the throttle valve 4 and the engine speed Ne. Is also good.

[0028]

As described above, according to the present invention, it is possible to satisfy a predetermined amount of wall adhesion at the time of starting in a short time, so that unnecessary cranking can be avoided and the starting time can be shortened. In addition, there is an effect that the exhaust characteristics at the time of starting can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a system schematic diagram showing one embodiment of the present invention.

FIG. 3 is a flowchart showing fuel control.

FIG. 4 is a time chart showing characteristics of an ejection pulse signal in the embodiment.

[Explanation of symbols]

 1 engine 6 fuel injection valve 12 control unit 14 crank angle sensor 15 water temperature sensor 16 starter switch

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02D 41/00-41/40

Claims (1)

(57) [Claims] An internal combustion engine comprising an injection control means for setting an injection pulse width corresponding to an intake air amount of an engine and outputting an injection pulse signal of the injection pulse width to a fuel injection valve at a predetermined timing synchronized with engine rotation. the fuel injection system of the engine, the start start detecting means for detecting the start of engine start, in a fixed starting control time from the detection of the start of the engine start by the above start moving start detecting means, before Ki噴 morphism control means Instead, a start-time asynchronous injection control means for outputting an injection pulse signal having a predetermined start injection pulse width to the fuel injection valve every predetermined injection interval time, an engine temperature detection means for detecting an engine temperature, and the engine temperature An injection interval time setting means for setting the injection interval time shorter as the engine temperature detected by the detection means is lower. Start control device.