JPH0656128B2 - How to prevent smoldering spark plugs - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for preventing smoldering of a spark plug, which is mainly applied to an engine of an automobile.

[Prior Art] Some recent automobile engines are equipped with an injector in the intake passage and an electronically controlled fuel injection device that controls the fuel injection amount from the injector by a microcomputer system. Not a few. In a multi-cylinder engine equipped with an electronically controlled fuel injection device, for example, as shown in Japanese Patent Laid-Open No. 58-27846, fuel injection from an injector provided for each cylinder corresponds to a constant cylinder. There are some that are made to run at the same time. FIG. 4 schematically shows the opening timing of the intake valve of each cylinder and the fuel injection timing from the injector in a three-cylinder engine that employs such a simultaneous fuel injection method.

[Problems to be Solved by the Invention] The following inconveniences occur in such a fuel injection system. That is, in this system, since the injector operation timing (fuel injection timing) is determined regardless of the intake stroke to the exhaust stroke of each cylinder as the engine starts, the intake valve is always opened only in a specific cylinder. Fuel injection will be performed at the time. As a result, the ignition plug in the cylinder may be directly sprayed with fuel, depending on the position where the ignition plug is arranged, which may cause smoldering of the ignition plug. Then, such a problem is intermittently performed from the time the engine is started to the time it is stopped. For example, as shown in FIG. 4 as an example, the ignition plug of the first cylinder is always exposed to the above-mentioned problems and smolders during the operation of the engine.

An object of the present invention is to prevent sudden smoldering of a specific spark plug by changing the fuel injection timing at regular intervals.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides an engine equipped with an electronically controlled fuel injection device for simultaneously injecting fuel to be supplied to each cylinder, with a predetermined fixed cycle. It is characterized in that the fuel injection timing is changed with each passage.

[Operation] In the present invention, since the fuel injection timing is changed every time a predetermined fixed period elapses, it is possible to avoid the problem that fuel is continuously applied only to a specific spark plug during engine operation. It Therefore, if the present invention having such a configuration is adopted in an engine equipped with an electronically controlled fuel injection device that simultaneously injects fuel to be supplied to each cylinder, smoldering of a spark plug can be effectively prevented.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a schematic diagram of a 1-cylinder portion in a 3-cylinder engine and an electronically controlled fuel injection device provided in the engine.
The engine 1 shown in the figure is a four-cycle engine, and inside thereof, there is no change from the normal state, and a piston 2 that reciprocates in a cylinder and an intake passage 4 that communicates with a combustion chamber 3 above the piston 2 are provided.
Side and the exhaust passage 5 side are provided with an intake valve 6 and an exhaust valve 7, and a spark plug 8 and the like mounted so as to face the top of the combustion chamber 3. The current of the ignition coil flows through the spark plug 8 via the distributor 9.

The electronically controlled fuel injection device 11 controls the injector 12 that injects fuel from the fuel tank into the intake passage 4 of the intake system, and the operation timing of the injector 12,
And a microcomputer system 13 for adjusting the injection amount of the fuel supplied to the combustion chamber 3.

The injector 12 is provided for each intake pipe 14 leading to each cylinder, and has an electromagnetic coil and the like inside thereof. When the drive signal F from the microcomputer system 13 flows through the electromagnetic coil, the fuel is atomized from the nozzle at the tip and injected into the intake passage 4 near the intake port.

The microcomputer system 13 is set so as to operate all the injectors 13 at the same time while adjusting the fuel injection amount from the injector 12 provided for each cylinder based on signals from various sensors and the like. It has a central processing unit 15, a memory 16, and interfaces 17 and 18. And
At least the signal G from the crank angle sensor 19 is input to the interface 17, and the interface 18 is directed toward each injector 12,
At the same time, the drive signal F is output.

The crank angle sensor 19 outputs a crank angle signal G for each constant rotation angle (240 ° CA) of the crankshaft based on the pulse current of the ignition coil introduced into the distributor 9, and the interface 17
It is designed to be input into.

The microcomputer system 13 includes
Programs such as those shown in FIGS. 2 and 3 are built in, and a function of changing the fuel injection timing from the injector 12 at every elapse of a predetermined fixed period is exhibited based on these programs. To be done.

First, when the engine is started, in step 51, the increment counter CIN from the start of the engine 1
It is determined whether the JG value is equal to or longer than a predetermined fuel injection timing change interval x (minutes), and if it is determined to be less than the change interval x, fuel injection is executed at each fuel injection timing up to that point. If it is determined that the fuel injection timing should be changed, the process proceeds to step 56. On the other hand, if it is determined that the change interval x is equal to or greater than the change interval x, it is determined that the fuel injection timing up to that time is changed, and the process proceeds to step 52. In step 52, it is judged whether or not the value of the first counter INJG has reached 2, and 2
If it is less than 1, go to step 53, and the first counter I
NJG is incremented by 1 and the routine proceeds to step 55. On the other hand, if it is determined that the value is 2 or more, the routine proceeds to step 54 where the value of the first counter CINJG is set to 0 and the routine proceeds to step 55. At step 55, the value of the increment counter CINJG is set to 0, and the routine proceeds to step 56.

In step 56, it is determined whether or not the signal G from the crank angle sensor 19 is input. If it is not input, it is determined that fuel injection should not be executed, the process returns to step 51, and it is determined that it is input. Go to step 57. In step 57, it is determined whether or not the value of the second counter CNTG is 2 or more. If it is determined that the value is less than 2, the process proceeds to step 58 and the value is incremented by 1 and the process proceeds to step 61. On the other hand, the second counter CNT
If it is determined that the value of G is 2 or more, the process proceeds to step 59, the value is set to 0 and the process proceeds to step 61. Step 6
1, the first counter INJG and the second counter CN
It is determined whether or not the TG values match, and if it is determined that they do not match, it is determined that fuel injection should not be performed and the process returns to step 51. If it is determined that they match, fuel injection is performed. If it is determined that it should be performed, the process proceeds to step 62, and fuel injection is executed.

Next, the operation of this embodiment will be described.

First, the timing of the increment counter CINJG is started when the engine is started. If the time from the start of measurement does not reach the fuel injection timing change interval x, the fuel injection is executed at the previous fuel injection timing. That is, in this case, on condition that the signal G from the crank angle sensor 19 is input, and the first counter INJG and the second counter CNTG are used.
If the values of the two match, the driving signal F is simultaneously output from the micro-computer system 13 to each injector 12, and fuel injection is executed (step 51).
→ 56 → 57 to 61 → 62).

On the other hand, when the value of the increment counter CINJG reaches the fuel injection timing change interval x, the fuel injection timing is changed to the conventional fuel injection timing (see position a in FIG. 2) and the position b is shifted by a constant crank angle (240 °). Fuel injection will be executed. That is, in this case, on condition that the signal G from the crank angle sensor 19 is input,
Also, the first counter INJG and the second counter CNT
When the values of G match, the drive signal F is simultaneously output from the microcomputer system 13 to each injector 12, and fuel injection is executed.
(Steps 51 → 52 to 55 → 56 to 61 → 62).

During the engine operation, the fuel injection timing is sequentially shifted by a constant crank angle (240 ° CA) each time the fuel injection timing change interval x elapses.

With such a configuration and operation, each time the value of the increment counter CINJG reaches a predetermined fuel injection timing change interval x, the fuel injection timing is fixed by a constant crank angle (240 °). It will shift sequentially. As a result, the problem that the injected fuel is directly applied to only the specific spark plug 8 in the multi-cylinder engine 1 is avoided, and the specific inconvenience that the spark plug 8 causes smoldering can be prevented.

In addition, in the above-mentioned embodiment, the lapse of a certain period of time is used as a guide,
Although the fuel injection timing is changed, the fuel injection timing may be changed each time the rotation amount of the crankshaft reaches a certain value.

Further, in the above-described embodiment, the fuel injection timing is shifted by a constant crank angle (240 °) because it is a 3-cylinder engine. However, in a multi-cylinder engine other than the above, the crank angle depends on the number of cylinders. It is desirable to set it.

[Effects of the Invention] As is clear from the above description, the present invention is an engine equipped with a fuel injection device that simultaneously injects fuel to be supplied to each cylinder, and the Since the injection timing is changed,
Smoldering of the spark plug can be effectively prevented.

[Brief description of drawings]

1 to 3 show one embodiment of the present invention, FIG. 1 is a schematic configuration explanatory view, FIG. 2 is a timing chart showing fuel injection timing, and FIG. 3 is a flow chart showing a control procedure, FIG. 4 is a timing chart showing a conventional example. 1 ... Engine 4 ... Intake passage 5 ... Exhaust passage 8 ... Spark plug 11 ... Electronically controlled fuel injection device 12 ... Injector 13 ... Microcomputer system 14 ... Intake pipe

Claims (1)

[Claims] 1. An engine equipped with an electronically controlled fuel injection device for simultaneously injecting fuel to be supplied to each cylinder, wherein the fuel injection timing is changed at each elapse of a predetermined fixed period. How to prevent smoldering spark plugs.