JPH0275758A - Air assist type electronic control fuel injection device - Google Patents

Abstract

PURPOSE:To improve response by a method wherein a control valve located in the middle of a piping through which assist air is fed is opened during detection of a transient state, e.g. the acceleration and the deceleration state of an engine, the feed of the assist air to a position in the vicinity of a fuel injection valve is stopped temporarily. CONSTITUTION:An air assist type electronic control fuel injection device feeds an assist air flow, called assist air, guided from the upper stream of a throttle valve 6, to a fuel injection valve 9 so that fuel particles injected through the injection valve 9 are fined, and injects the assist air to an intake air port simultaneously with injection of fuel. In this case, a solenoid valve 18 operation of which is controlled by a computer 17' is situated in the middle of a piping 10. When a transient state is detected by means of signals from a throttle switch 14 and an intake air pipe negative pressure sensor 7, the solenoid valve 18 opened, and the feed of air assist to the fuel injection valve 9 is stopped. In this constitution, a spray angle of fuel is switched from a type B to a type A, and by reducing an amount of fuel adhered to a pipe wall 19, almost the whole of injection fuel is introduced to a combustion chamber 20.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is an electronically controlled fuel injection device (hereinafter abbreviated as EFI) for an internal combustion engine, which is an electronically controlled fuel injection device (hereinafter abbreviated as EFI) for promoting fuel atomization. This invention relates to an improvement in an air assist system that uses air flow (hereinafter referred to as air assist II EFI).

[Conventional technology]

The conventional technology for Air Assist II EFI is
There is one described in Japanese Patent No.-143158. Figure 6 shows the outline, where ■ is the intake valve, 2 is the cylinder head, 3 is the piston, 4 is the intake boat, 5 is the surge tank,
6 is a throttle valve, 7 is an intake pipe negative pressure sensor, 8 is an air flow sensor, 9 is an air assist type fuel injection valve, 10 is piping, 11 is an electric air pump, 12 is a linear solenoid valve, 13 is an assist air inlet, 14 is a throttle inch, 15 is a rotation speed sensor, 16 is a water temperature sensor, 1
7 is a combination train.

Air Assist 2 EFI supplies an auxiliary air flow (referred to as assist air) led from upstream of the throttle valve to the injection valve in order to make the fuel particles injected from the fuel injection valve finer. However, simply obtaining airflow by using the pressure difference before and after the throttle valve may not be able to obtain a sufficient flow rate as assist air, so the conventional technology described above , at startup or under high load when the differential pressure across the throttle valve is small,
Alternatively, various sensors detect when the cooling water temperature is extremely low, and the electric air pump 11 is driven based on judgment and instructions from the computer 17, and the linear solenoid valve 12 is appropriately throttled to allow assist air to flow to the fuel injection valve 9. is increasing.

[Problem to be solved by the invention]

In terms of being able to make fuel particles finer and reducing hydrocarbons (HC) in exhaust gas,
Air Assist II EFI has a remarkable effect, but in a transient state such as when a car equipped with it suddenly accelerates from a constant speed driving state, the throttle valve opens and the intake air volume increases. Even if the computer increases the amount of fuel coming out of the injection valve based on the signal from the airflow sensor that detects this, the air-fuel mixture entering the engine from the intake valve becomes temporarily lean (such a significant change in the air-fuel ratio is
(referred to as "rough air-fuel ratio"), the engine may temporarily malfunction.
It has been found that there is a problem in that a sharp increase in output cannot be obtained. Therefore, we investigated the cause of such a phenomenon and found that, as shown in Figure 3 (B), in Air Assist II EFI, the assist air promotes atomization of the fuel, but the spray angle is ), a considerable portion of the sprayed fuel collides with the intake pipe wall 19 near the intake port 4 and returns to liquid state, causing the pipe wall to become wet. Under steady state conditions such as constant-speed operation, the amount of new adhesion and the amount of evaporation carried by the intake air are balanced, so there is no problem. In this case, the amount of fuel is increased, so the amount of fuel adhering to the pipe wall increases temporarily and the amount of fuel entering the combustion chamber does not increase much, whereas the amount of air increases significantly without any such problem. In addition, when accelerating, the throttle valve opens and the pressure near the intake port becomes close to atmospheric pressure, creating a considerable amount of negative pressure at the intake port as in the previous constant speed operation state. Due to two reasons, evaporation of the liquid fuel adhering to the tube wall is reduced due to the absence of liquid fuel, resulting in "roughness of the air-fuel ratio" in the form of temporary leanness of the air-fuel mixture in the combustion chamber. It was found that this occurs.

In this way, Air Assist II EFI causes roughness in the air-fuel ratio during transient conditions such as acceleration and deceleration of the engine.
It is an object of the present invention to solve these problems.

[Means to solve the problem]

The present invention solves the above problem by providing a fuel injection valve, a pipe for supplying assist air to the injection valve to promote atomization of the fuel injected from the injection valve, and a pipe provided in the middle of the pipe. This problem is solved by an air-assisted electronically controlled fuel injection system, which is characterized by being provided with a control valve that is closed, and a control means that closes the control valve in a transient state of engine operation.

[For production]

Since the present invention has the above configuration, when a transient state such as an acceleration state or a deceleration state of the engine is detected, the control means closes the control valve provided in the middle of the piping that supplies assist air. Therefore, the assist air that has passed through this control valve and been supplied to the vicinity of the fuel injection valve is temporarily stopped. When assist air is being supplied, the atomization of the fuel is promoted, but because the spray angle becomes large, some of the spray collides with the wall of the intake pipe near the intake port and returns to liquid form. , the fuel was supplied to the combustion chamber after a certain time delay through the process of wetting the pipe wall and evaporating again, but when the assist air passing through the solenoid valve stopped, the spray angle of the fuel injector became smaller. To,
The fuel spray is immediately drawn into the combustion chamber of the engine without any time delay. Therefore, even in a transient state where the engine speed fluctuates greatly, there is no ``roughness in the air-fuel ratio'', temporary engine malfunctions are avoided, and acceleration is performed without delay, resulting in excellent responsiveness. You will be able to get a better organization.

[Embodiment] FIG. 1 shows a first embodiment of the present invention. E in the present invention
Since the basic configuration of the Fr is the same as that shown in FIG. 6 showing the prior art, illustration or explanation thereof will be omitted in the embodiments as well. In the case of this embodiment, the electric air pump 11 in the prior art is not used.

Assist air supply is basic air assist 2EFI.
Similarly, this is done by the differential pressure before and after the throttle valve 6. As a feature of the present invention, in the first embodiment, a solenoid valve 18 that is opened and closed by a computer 17' is provided in the middle of the assist air piping IO.

When a transient state such as acceleration or deceleration is detected by signals from the throttle switch 14 and the intake pipe negative pressure sensor 7, the computer 17' issues a command to close the solenoid valve 18. Therefore, when the internal combustion engine that has been in a steady state of operation shifts to a transient state, assist air is no longer supplied to the fuel injection valve 9, and the fuel spray angle changes as shown in FIG.
The shape of B) switches to the shape of (A), the amount of fuel adhering to the pipe wall 19 decreases, and almost all of the injected fuel enters the combustion chamber 20 as it is.

The flowchart in FIG. 4 shows the operation of the computer 17'. In this example, sudden acceleration and deceleration are the only transient conditions that need to be addressed, since gradual acceleration does not cause many problems. Throttle valve 6
When the throttle switch 14, which indicates opening/closing of
．． If I≧A), the computer 17' determines in step 100 that there is a sudden acceleration state, and issues a command to close the solenoid valve 18 in step 101. If step 100 is NO, the process proceeds to step 102 and the throttle switch is turned OFF.
N (throttle valve 6 closed) and the intake pipe negative pressure is at the predetermined value B.
When it is larger than (P, 4≦B), it is determined that the deceleration state is occurring, and a command to turn off the solenoid valve 18 is also issued in step 101. N at step 102.

In this case, the computer 17' issues a command to open the solenoid valve 18 in step 103, assuming that the state is steady.

Note that the throttle indicated by 21 in the figure is a resistance flow path that bypasses the solenoid valve 18, and has the effect of preventing the amount of assist air from becoming zero even when the solenoid valve 18 is closed. Aperture 2
1, the small amount of assist air that passes through it will slightly expand the spray angle of the injected fuel, but if this expansion is not a problem, the assist air can be stopped even in a transient state by such means. This exemplifies that the object of the present invention can also be achieved by such a means, since it is possible to achieve atomization of the atomized spray by reducing the amount of particles rather than reducing the amount of particles.

Furthermore, by directing the center of the spray injected from the fuel injection valve 9 toward the umbrella portion of the intake valve 1, it is possible to further prevent the spray from adhering to the intake boat when the spray angle of assist air becomes small. .

FIG. 2 shows a second embodiment, which differs from the first embodiment in that the assist air is supplied by the differential pressure before and after the throttle valve 6, instead of being supplied with air pump 22. There is a solenoid valve 1 in the assist air piping 10 that is opened and closed by a computer 17''.
The provision of the diaphragm 8' and the provision of the diaphragm 21' if necessary are the same as in the first embodiment. In the case of the second embodiment, in the steady state, as in the prior art described above,
Since there is no shortage of assist air, sufficient assist air can be obtained even in a steady state of high load, for example when the throttle valve 6 is fully open and the intake pipe negative pressure Px is reduced, and also during transient states such as acceleration and deceleration. In this case, the purpose of the present invention can be achieved in the same way as in the first embodiment by stopping or reducing the assist air.

Next, as a third example, although illustration of the structure is omitted, the first
An example will be described in which, in addition to the throttle switch 14, a sensor (for example, a potentiometer) for generating a throttle opening signal and inputting it to the computer 17' is provided on the shaft of the throttle valve 6 in the figure. In this case, the amount of change in throttle opening within a unit time is the differential value ΔTA of the opening signal.
is calculated in the computer 17', and based on it, the computer IT' performs the operations shown in the flowchart of FIG. In this example, 5 m5ec
First, in step 200, the rate of change ΔTA of the throttle opening is compared with a predetermined value X. If ΔTA≧X, it is determined that there is an acceleration state, and the process proceeds to step 201, where the computer 17' instructs the solenoid valve 18 to close for 2 seconds.

Therefore, the assist air stops and the fuel spray shape becomes as shown in FIG. switch 1
It is checked by the signal No. 4 (LLON indicates that the throttle valve 6 is fully open).

If it is fully open (Yes), it is determined that it is in a deceleration state, and the process also proceeds to step 201, in which the solenoid valve 18 is commanded to close for 2 seconds. If the throttle valve 6 is open (NO) in step 202, it is determined that the steady state is present, and the process proceeds to step 203, in which the solenoid valve 18 is commanded to open.

In the case shown in the flowcharts of Figures 4 and 5,
In both cases, in addition to acceleration, deceleration is also recognized as a transient state, and the assist air is stopped (or reduced).The reason for this is that engine deceleration is generally performed prior to gear change. In many cases, the engine will start accelerating again after the gear change has finished, so rather than stopping the assist air for 2 seconds after starting acceleration, in addition to that, the engine will start accelerating again from the time the previous stage of deceleration started. This is because if the assist air is stopped for 2 seconds, most of the fuel adhering to the pipe wall during acceleration is gone, so that it is possible to better prevent the air-fuel ratio from becoming rough.

〔Effect of the invention〕

Since the present invention has the above-described configuration, while maintaining good atomization of fuel by assist air during steady operation, during transient states such as acceleration and deceleration,
By stopping or reducing the blowout of assist air, the spray angle of the fuel injector is reduced to prevent the air-fuel ratio from becoming rough.
It has the effect of preventing the engine from falling into a temporary slump and allowing a sharp increase in output to be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing a second embodiment, and FIG. 3 is a case (A) in which no air assist is applied to the fuel injection valve. A comparison diagram showing the spray angle when air assist is performed (B), FIG. 4 is a flowchart showing the control pattern of the solenoid valve inserted into the assist air piping, and FIG. 5 is a flowchart showing other control patterns. FIG. 6 is a longitudinal cross-sectional view showing the configuration of the conventional air assist device II. ■...Intake valve, 4...Intake boat, 6...
・・Throttle valve, 7・Intake pipe negative pressure sensor, 8・
...Air flow sensor, 9...Air assist type fuel injection valve, 10...Distribution percentage F, 11...Electric air pump, 12...Linear solenoid valve, 13...Air inlet, 14...・Throttle switch, 15... Rotation speed sensor, 16... Water temperature sensor, 17
, 17', 17''...computer, 18
, 18'... Solenoid valve, 19... Pipe wall, 20...
・Combustion chamber, 21, 21'... Throttle, 22・
・Air pump.

Claims (1)

[Claims] A fuel injection valve, a pipe for supplying assist air to the injection valve to promote atomization of fuel injected from the injection valve, a control valve provided in the middle of the pipe, and the control valve. An air-assisted electronically controlled fuel injection device comprising a control means for closing a valve in a transient state of engine operation.