JPH02176123A - Air-fuel ratio control mechanism for fuel injection device - Google Patents

Abstract

PURPOSE:To feed an air-fuel mixture with oombustible concentration to an engine at the time of deceleration by opening a passage applying the manifold negative pressure to a negative pressure chamber at the time of deceleration. CONSTITUTION:A negative pressure guiding passage 19 applying the manifold negative pressure to a negative pressure chamber 10 and an opening/closing control means 20 opening this passage at the time of deceleration are provided in a pressure balance type fuel injection device. When an engine brake is applied for deceleration from the acceleration state, a throttle valve 4 is decreased to idle opening, and the air flow is decreased. The opening/closing control means 20 opens the passage 19 at this time, the increased manifold negative pressure is applied to the negative pressure chamber 10, the pressure difference from an atmospheric pressure chamber 12 is increased, and the fuel discharge quantity is increased. The concentration of the air-fuel mixture fed to an engine is increased, afterburning can be prevented, the fuel stuck on the wall face of a manifold is not evaporated, thus the subsequent acceleration can be smoothly performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure-balanced fuel injection device, and more particularly to a mechanism for controlling the air-fuel ratio of an air-fuel mixture during deceleration.

[Conventional technology]

Conventionally, there is a pressure-balanced fuel injection device, for example, one filed by the present applicant in Utility Model Application No. 169266/1985, in which afterburn occurs during deceleration unless special measures are taken. That is, FIG. 3(A)
As shown in (C), when the engine brake is applied to decelerate from an accelerated state, the throttle valve becomes idling (see (A) in the same figure), and the fuel that has adhered to the wall of the manifold is temporarily removed. is evaporated and inhaled, and the air-fuel ratio becomes rich (but then quickly becomes thinner), resulting in incomplete combustion in the cylinder and an explosion in the exhaust pipe, resulting in afterburn (see figure (C)).

Afterburn can be prevented by enriching the air-fuel ratio of the mixture so that it can burn inside the cylinder, or by making it leaner so that it does not burn. The applicant proposed a means to prevent afterburn by reducing the air-fuel ratio in U.S. Pat. The system closes the valve and stops the discharge of fuel, reducing the air-fuel ratio to prevent complete combustion and preventing afterburn.

[Problem to be solved by the invention]

However, in this method of reducing the air-fuel ratio, the fuel adhering to the manifold wall surface is evaporated and sucked into the engine in order to reduce the amount of fuel discharged during deceleration. As a result, the manifold wall surface becomes dry, and even if fuel is injected during acceleration from deceleration, some of it sticks to the wall surface and is not inhaled by the engine, causing a short-term lean air-fuel ratio to occur in the form of a spike. After a lean spike occurs and the engine torque disappears, torque is suddenly generated, which tends to cause a shock during acceleration.

In view of these problems, the present invention provides a fuel injection device that prevents afterburn by supplying an air-fuel mixture with a combustible concentration to the engine during deceleration and enables smooth subsequent acceleration. The purpose is to provide an air-fuel ratio control mechanism.

[Means to solve the problem]

The air-fuel ratio control mechanism of the fuel injection device according to the present invention is designed to balance the pressure difference between the negative pressure chamber and the atmospheric pressure chamber depending on the air flow rate, and the fuel pressure difference before and after the jet that communicates the upstream chamber and the downstream chamber. A pressure-balanced fuel injection device that controls the amount of fuel discharged during deceleration is equipped with a passage for applying negative pressure to a negative pressure chamber in a manifold, and an opening/closing control means that normally closes this passage and opens it during deceleration. There is.

[Effect]

If you apply engine braking to decelerate from an accelerated state,
The throttle valve is reduced to idle opening and the air flow rate is reduced, but since the opening/closing control means opens the passage, increased manifold negative pressure is applied to the negative pressure chamber, increasing the pressure difference with the atmospheric pressure chamber. As a result, the amount of fuel discharged also increases.
The concentration of the air-fuel mixture supplied to the engine increases, preventing afterburn, and also prevents fuel adhering to the walls of the manifold from evaporating.

〔Example〕

Hereinafter, a preferred embodiment of the present invention will be described based on a schematic cross-sectional view of an air-fuel ratio control mechanism of a fuel injection device shown in FIG.

In the figure, l is an intake passage, 2 is a venturi part in the intake passage l, 3 is an air valve provided downstream of the venturi part 2 and has openings 3a and 3b in the minimum opening state, and 4 is further downstream of the air valve 3. A throttle valve 5 disposed on the side is a slow system fuel control means, and the main system fuel control means is omitted in the figure. 6 is connected to the intake passage 1 on the downstream side of the air valve, and the opening 3 is connected to the intake passage 1 in the slow zone.
a slow negative pressure passage that applies negative pressure to the slow system fuel control means 5 in accordance with the air flow rate flowing through a; Although the manifold negative pressure and the air valve downstream negative pressure introduced into the passages 8.9 through 8a and 9a are combined and applied, these passages 8 and 9 may not be provided.

In the slow system fuel control means 5, 10 is a negative pressure chamber that communicates with the slow negative pressure passage 6 and to which air valve downstream negative pressure is applied, and 11 is a negative pressure chamber 10 and an atmospheric pressure chamber 12 to which atmospheric pressure is applied. 13 is an upstream chamber into which fuel is sent from the fuel supply source; 14 is a fuel discharge port 14;
15 is the upstream chamber 13 and the downstream chamber 14.
16 is a fuel metering jet that communicates the upstream chamber 13 and downstream chamber 14, 17 is a fuel metering jet that connects both diaphragms 11.15, and a valve 17a that can open and close the discharge port 14a is formed in the middle. When a negative pressure corresponding to the flow rate of air flowing through the intake passage 1 is applied to the negative pressure chamber 10, a pressure difference with the atmospheric pressure chamber 12 is generated, and the negative pressure diaphragm 11 is connected to the negative pressure chamber 10. The valve 17a and the fuel diaphragm 15 are also displaced accordingly, and a fuel flow rate corresponding to the air flow rate is injected from the discharge port 14a.
The pressures applied to nodes 1 and 15 are balanced. A bleed air passage 18 communicates the upstream side of the venturi portion 2 and the downstream side of the throttle valve 4 in the intake passage l via a throttle 18a, and communicates with the discharge port 14a on the downstream side of the throttle 18a. The fuel flow rate injected from the outlet 14a passes through this passage 18 and is discharged to the manifold. The above configuration is similar to the prior art described above.

19 is a negative pressure introduction passage that communicates the negative pressure chamber 10 with the intake passage 1 on the downstream side of the throttle valve; 20 is an opening/closing control means provided in the middle of this passage 19 for controlling opening/closing of this passage 19; In this means 20, 21 is a third chamber communicating with the intake passage 1 on the downstream side of the throttle valve;
23 is a diaphragm that partitions both chambers 21 and 22; 24 is connected to the diaphragm 23 and can open and close the negative pressure introduction passage 19; valve, 25 is valve 2
The valve 24 is a spring that presses the diaphragm 23 in the valve closing direction of the valve 4, and the valve 24 opens when a manifold negative pressure of about 590 mmHg is applied to the first chamber 21 when the throttle valve 4 is at an idle opening. The elasticity of the spring 25 is set as shown in FIG.
0 and functions as a throttle, and adjusts the amount of manifold negative pressure applied to the negative pressure chamber 10 depending on the forward/backward position of this adjustment screw 26, thereby adjusting the air-fuel ratio during deceleration. The darkness can be adjusted, and during normal driving, it remains fixed after adjusting the forward and backward positions.

The present embodiment is constructed as described above, and its operation will be explained next.

In the acceleration state, the required air flow rate is sent to the manifold of the intake passage 1 according to the opening degree of the throttle valve, and the negative pressure introduction passage 19 is closed by the opening/closing control means 20. When the throttle valve 4 is decelerated, the throttle valve 4 is closed to the idle opening degree, the manifold negative pressure increases, and the opening/closing control means 20
A negative pressure exceeding 590 mmHg is applied to the chamber 21. Then, since the negative pressure downstream of the air valve applied to the second chamber 22 has also decreased, the diaphragm 23 is displaced toward the second chamber 21 against the elasticity of the spring 25, and the valve 24 is opened to release the manifold negative pressure. Pressure is applied to negative pressure chamber 10 . In the slow system fuel control means 5, the valve 17a moves in the direction of closing the discharge port 14a due to the decrease in the negative pressure downstream of the air valve, but when the negative pressure in the negative pressure chamber 10 increases again due to the introduction of manifold negative pressure, the negative pressure The diaphragm 11 is displaced toward the negative pressure chamber 10, the opening area of the valve 17a and the discharge port 14a increases, and the flow rate of fuel discharged into the intake passage l increases, stably as shown in FIG. A rich mixture is supplied to the engine and afterburn is prevented. In addition, since the fuel adhering to the manifold wall does not evaporate and the wall surface dries, smooth acceleration is possible without lean spikes when acceleration is subsequently started.

When acceleration starts, the manifold negative pressure decreases, the opening/closing control means 20 closes the negative pressure application passage 19, and the slow system fuel control means 5 returns to its normal operating state.

Also, the manifold negative pressure during idling is usually 500~
Since it is about 560 mmHg, the opening/closing control means 20 will not be opened except during deceleration.

As described above, according to the present embodiment, afterburn during deceleration can be prevented, and lean spikes do not occur during acceleration after deceleration (smooth acceleration can be achieved).

Note that a solenoid valve may be used as the opening/closing control means to detect the manifold negative pressure and electrically control the opening/closing of the negative pressure introducing passage 19.

In addition, the adjustment screw 26, which functions as a throttle for the negative pressure introduction passage 19, can be electrically controlled using a linear solenoid or the like, so that it can be moved forward or backward according to the engine speed and throttle opening, thereby reducing the airflow during deceleration. The fuel ratio may be automatically adjusted.

〔Effect of the invention〕

As described above (according to the air-fuel ratio control mechanism of the fuel injection device according to the present invention), the opening/closing control means opens the negative pressure introduction passage during deceleration and applies the manifold negative pressure to the negative pressure chamber. In addition to preventing afterburn during acceleration, lean spikes do not occur during acceleration after deceleration (smooth acceleration can be achieved).

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the air-fuel ratio control mechanism of a fuel injection device according to the present invention, FIG. 2 is a diagram showing the air-fuel ratio of the air-fuel mixture during deceleration, etc., and FIGS. C) relates to a conventional device, in which (A) shows the throttle valve opening, (B) shows the engine speed, and (C) shows the air-fuel ratio of the air-fuel mixture. 3@+11111 air valve, 4@@66 throttle valve, 5... Slow system fuel control means, lO...
Negative pressure chamber, 11... Negative pressure diaphragm, 12...
Atmospheric pressure chamber, 13...upstream chamber, 14...φ/downstream chamber,
15... Fuel diaphragm, 16... Jet, 19... Negative pressure introduction passage, 20... Opening/closing control means. 1F1 diagram

Claims (1)

[Claims] The fuel discharge amount is controlled to balance the pressure difference between the negative pressure chamber and the atmospheric pressure chamber, to which negative pressure is applied depending on the air flow rate, and the fuel pressure difference between the chambers before and after the jet. A pressure-balanced fuel injection device that maintains a constant fuel ratio includes a passage for applying manifold negative pressure to the negative pressure chamber, and an opening/closing control means that normally closes the passage and opens it during deceleration. An air-fuel ratio control mechanism.