JPS63143346A - Fuel supply controlling method for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent a sudden change in an air-fuel ratio from occurring, by having an air throttle valve fully closed at time of specified low speed of an engine and/or at time of specified low opening of a throttle valve, in case of a device which sets up common fuel injection valves at the upstream of a throttle valve and installs the air throttle valve at the upstream side. CONSTITUTION:During drive of an engine 1, each output signal out of a throttle valve opening sensor 8, a cooling water temperature sensor 9 and an engine speed sensor 10 is inputted into an engine control unit 5, and an air throttle valve 7 is controlled for opening or closing according to the engine driving state judged from these signals. That is to say, when the engine 1 is not in a high speed state and it is in a low water temperature state, a pressure selector valve 22 is excited, leading the atmosphere into a vacuum chamber 20a of a diaphragm device 20, and the air throttle valve 7 is closed. And, even in case of being not in a low water temperature state, and at time of being in a low speed state as well as even at time of a low throttle opening state in a medium speed state, the air throttle valve 7 is controlled so as to be closed. In a driving state other than that, the air throttle valve 7 is controlled according to Venturi negative pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel supply control method for an internal combustion engine, and in particular to a method for controlling fuel supply for an internal combustion engine, particularly for a type of internal combustion engine in which fuel is supplied to multiple cylinders by a common fuel injection valve disposed upstream of a throttle valve. The present invention relates to a fuel supply control method for an internal combustion engine.

(Prior art and its problems) Conventionally, as a method of supplying fuel to an internal combustion engine equipped with multiple cylinders, fuel is injected and supplied to multiple cylinders using a common fuel injection valve placed upstream of the throttle valve in the intake pipe. It is known that the number of fuel injection valves is reduced by doing so, thereby reducing the cost of the fuel injection device.

In this case, in order to ensure good drivability and exhaust gas characteristics, it is essential to distribute fuel evenly to multiple cylinders. It is necessary that the atomization is sufficiently atomized on the upstream side of the branching part. On the other hand, in order to ensure high output from the engine, the fuel injection valves must have a large fuel flow rate so that a large amount of fuel can be supplied to each cylinder in a short time by a common fuel injection valve at high loads. A large opening area is required, which makes it particularly difficult to use during low-load operation when the intake air flow rate is low or when the intake pipe wall temperature is low.
The atomization characteristics of the fuel injection valve itself will be poor.

Therefore, in order to ensure both high output and good drivability of the engine, it is necessary to use a fuel injection valve with a large fuel flow rate and to direct the fuel injected from the fuel injection valve upstream of the branch part of the intake pipe. It is necessary to achieve sufficient atomization on the side, and one of the conventional technologies to meet these requirements is an air throttle valve with a notch in the valve body as a throttle opening.

There is one in which the notch is located opposite the fuel injection valve discharge port upstream of the throttle valve when the valve is closed (USP
4,378,000). In this case, a venturi similar to a carburetor is installed between the air throttle valve and the throttle valve, and the air flow rate near the fuel injection valve discharge port is adjusted by opening and closing the air throttle valve according to the negative pressure of the venturi. . That is, when the engine is under low load and at low engine speeds, the air throttle valve is controlled to the closed position due to a decrease in venturi negative pressure, and at this closed position, the throttling action of the notch of the air throttle valve facing the fuel injection valve discharge port is activated. This increases the flow velocity of intake air passing near the discharge port, thereby improving the atomization of the injected fuel.

However, in this control method, the air throttle valve is controlled only according to the venturi negative pressure, so when the engine is in a low water temperature or low rotation state, or when the throttle valve is in a low opening state, However, depending on the operating condition of the engine, the air throttle valve opens and the required fuel atomization cannot be obtained, resulting in a reduction in drivability. In other words, when the engine is in a low water temperature state, the air flow velocity increases as the engine speed increases, and when the venturi negative pressure increases, the air throttle valve opens; In addition to reducing the air flow velocity due to the valve, the intake pipe wall temperature is also low due to the low engine temperature, which increases the amount of fuel adhering to the throttle valve, etc., and reduces the amount of fuel supplied to each cylinder. , the air-fuel mixture becomes lean, resulting in a decrease in engine output.

Additionally, when the engine is running at extremely low speeds and the throttle valve is opening at an extremely low opening, the air flow rate is extremely small, so almost no venturi negative pressure is generated, so the air throttle valve is closed. However, as the engine speed or throttle valve opening gradually increases, the air flow rate also gradually increases, and the venturi negative pressure increases due to the throttling action of the air throttle valve, causing the air throttle valve to open. Since the air pressure reaches this level, the air throttle valve is once opened at a large opening. As a result, the air flow rate changes, but before the air throttle valve opens, the air throttle valve itself throttles the air and the flow rate of air is small, so the rate of change in the air flow rate before and after the air throttle valve opens. As the air-fuel ratio increases, the air-fuel ratio of the mixture supplied to each cylinder changes suddenly, resulting in fluctuations in engine output.At the same time, the opening of the air throttle valve reduces the air flow velocity, causing an increase in fuel flow. The atomization condition also deteriorates.

(Object of the Invention) The present invention has been made in order to solve the above-mentioned problems of the prior art, and it ensures a good atomization state of the injected fuel even when the engine speed is low and the throttle valve opening is low. It is an object of the present invention to provide a fuel supply control method for an internal combustion engine that allows stable drivability to be obtained.

(Means for Solving the Problems) In order to achieve the above object, the present invention is provided upstream of an intake pipe gathering part of an internal combustion engine having a plurality of cylinders, and the opening degree is adjusted according to the position of the accelerator pedal. A fuel injection valve is arranged upstream of the throttle valve to be adjusted to supply fuel to the plurality of cylinders, and an air throttle valve is arranged so that the throttle opening faces the discharge port of the fuel injection valve when fully closed. In the fuel supply control method for an internal combustion engine, the throttle opening increases the flow velocity of intake air near the discharge port of the fuel injection valve, wherein The air throttle valve is controlled to a fully closed position when at least one of the low opening conditions is satisfied.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a fuel supply control device to which the method of the present invention is applied. Reference numeral 1 indicates, for example, a 4-cylinder, 4-cycle internal combustion engine, and the engine 1 is connected to an intake pipe through an intake pipe collection portion 2a. 2 are connected. A throttle body 3 is provided upstream of the gathering portion of the intake pipe 2, and a throttle valve 3' is provided inside. A throttle valve opening degree (hereinafter referred to as [θ〒H sensor]) 8 is connected to the throttle valve 3' and converts the valve opening degree of the throttle valve 3' into an electrical signal, which is then sent to an electronic control unit (hereinafter referred to as [ECU]). )
It is set to be sent to 5th.

A fuel injection valve 6 and an air throttle valve 7 are provided upstream of the throttle body 3 of the intake pipe 2, respectively. The fuel injection valve 6 is for supplying fuel to all cylinders of the internal combustion engine 1 when the internal combustion engine 1 is in operation other than idling, and the air throttle valve 7 is for the intake near the discharge port of the fuel injection valve 6. This is for adjusting the air flow rate.

As shown in FIG. 2, the valve body 7a of the air throttle valve 7 has a disc shape with a notch 7a' as a throttle opening on its periphery, and in the closed position shown by the solid line in FIG. The upstream interior of the throttle body 3 is opened to a certain minimum opening area, which is the opening area of the notch 7a'. When the air throttle valve 7 is in the closed position, its notch 7a'
is arranged to face the discharge port of the fuel injection valve 6.

The air throttle valve 7 is constituted by a pressure-operated valve.

That is, the diaphragm device 20 that is the actuator
The negative pressure chamber 20a is connected to a port 23a that opens to the venturi section 4 on the upstream side of the throttle body 3 via a pipe line 21, a pressure switching valve 22, and a pipe line 23, and the negative pressure chamber 20a is defined. A diaphragm 20c is biased by a spring 20b, and a rod 2 has one end pivotally connected to the support 7b of the air throttle valve 7 via a pivot 7d.
It is connected to the other end of 0d. The support body 7b is rotatably mounted on a fixed support shaft 7c, and the valve body 7a is fixed to the support body 7b so as to be rotatable therewith.

When the venturi negative pressure Pv increases, the diaphragm 20c is displaced against the biasing force of the spring 20b, and the rod 20d
, the valve body 7a of the air throttle valve 7 is rotated clockwise via the pivot 7d and the support body 7b to the position indicated by the two-dot chain line in FIG.
As the venturi negative pressure Pv increases, the valve rotates toward the valve-closing side (toward the solid line in FIG. 1) as Pv decreases, and to the valve-opening side (toward the chain double-dashed line in FIG. 1) as the venturi negative pressure Pv increases.

Further, the pressure switching valve 22 has a solenoid 22a and a valve body 22b that opens an opening 22c and a pipe line 23 on the side of the venturi section 4 when the solenoid 22a is deenergized and energized, and the solenoid 22a is deactivated. During the peak period, the pipe 2
3 is opened to allow communication between the negative pressure chamber 20a and the venturi portion 4, but when the solenoid 22a is energized, the pipe line 23 is closed and communication is established between the negative pressure chamber 20a and the atmosphere via the filter 24. The air throttle valve 7 is held in the closed position regardless of the magnitude of the venturi negative pressure Pv.

On the other hand, an auxiliary fuel injection valve 6a is provided on the downstream side of the throttle body 3 of the intake pipe 2 and upstream of the intake pipe gathering portion 2a. It tries to supply fuel to all cylinders. The auxiliary fuel injection valve 6a is connected to a fuel tank 34 via a pipe 31, a strainer 32, and a pipe 33. Further, the auxiliary fuel injection valve 6a and the fuel injection valve 6 are connected through a pipe 30, and a fuel pump 35 pressure-feeds fuel to the fuel injection valve 6 through these pipes. The fuel injection valve 6 and the fuel tank 3
4 are connected with return pipes 37 and 38 having a pressure regulator 36 interposed therebetween. Further, the negative pressure chamber 36a of the pressure regulator 36 is connected to the downstream side of the throttle valve 3' of the intake pipe 2 via a conduit 39.

Negative pressure downstream of the throttle valve 3' in the intake pipe 2 and the spring 3
The valve opening pressure of the valve body 36c is set by the urging force of the valve body 6b. Therefore, the fuel pressure inside the pipes 30, 31, etc. is controlled by the pressure regulator 36, and the throttle valve 3'
The pressure is adjusted to be a certain pressure higher than the intake pipe internal pressure on the downstream side.

The engine cooling water temperature sensor (rT) is installed on the engine 1 body.
A sensor (referred to as "w sensor") 9 is provided. The Tw sensor 9 is composed of a thermistor or the like, and is inserted into the circumferential wall of the engine cylinder filled with cooling water.

The detected water temperature signal is supplied to EC:U5. Further, an engine rotation speed sensor (hereinafter referred to as "rNe sensor") 10 is attached around a camshaft or crankshaft (not shown) of the engine 1. The Ne sensor 10 is detected at a predetermined crank angle position every time the engine crankshaft 180' rotates, that is, at the top dead center (TDC) at the start of the intake stroke of each cylinder.
), the crank angle position signal (hereinafter referred to as "TDC signal") is generated at the crank angle position before the predetermined crusher 0 degrees.
This TDC signal is sent to the ECU 3.

The ECU 3 has an input circuit 5 having functions such as shaping input signal waveforms from various sensors, correcting voltage levels to predetermined levels, and converting analog signal values into digital signal values.
a. Central processing circuit (hereinafter referred to as r(::PUJ)) 5
b, a storage means 5c for storing various calculation programs and calculation results executed by the CPU 5b, and a pressure switching valve 22
and an output circuit 5d that supplies drive signals to the fuel injection valve 6 and the auxiliary fuel injection valve 6a, respectively.

The CPU 5b executes the control program for the pressure switching valve 22 shown in FIG. 3 and the fuel supply control program (not shown) in the T
Execute every time a DC signal is input. Based on these control programs, the CPU 5b controls the solenoid 22a of the pressure switching valve 22 on and off in accordance with engine parameter signals from the various sensors described above supplied via the input circuit 5a, and also controls the fuel injection valve. 6 and the auxiliary fuel injection valve 6a are calculated.

FIG. 3 shows the above-mentioned pressure switching valve 22 executed by the CPU 5b.
2 is a flowchart of a control program. The program is executed every time the TDC signal occurs.

First, in step 301, it is determined whether the engine rotation speed Ne is smaller than a first predetermined value Nepvc, (for example, 2.OOOrpm). If this answer is affirmative (Yss), that is, Ne (Nepvco), proceed to step 302;
It is determined whether the engine cooling water @Tw is smaller than a predetermined value Twρvc (for example, 60° C.). Step 3
The answer to 02 is affirmative (Yes), that is, N e < Nepv
c.

In addition, when T w < T wpvc holds, that is, when the engine 1 is not in a high rotation state and in a low water temperature state, the process proceeds to step 303, and t D! is used in step 306, which will be described later. : Set the LAY timer for the specified time toa+-A
y (for example, 0.3 sec), the process proceeds to step 307, and the solenoid 22a of the pressure switching valve 22 is energized to establish communication between the negative pressure chamber 20a of the diaphragm device 20 and the atmosphere. Atmospheric pressure is introduced into the negative pressure chamber 20a, the air throttle valve 7 is closed, and this program ends. Even with this valve closed, when the amount of intake air is large, such as when the engine is operating under high load,
The air throttle valve 7 is opened slightly by the dynamic pressure of the intake air.

The answer to step 302 is negative (No), that is, Tw≧T.
When the engine speed No. wpvc, the process proceeds to step 304, and the engine rotation speed No.
pn). The step 304
The answer is affirmative (Yes), that is, Tw≧T vpvc and N
When e<N e pvcl is established, that is, when the engine 1 is in a low rotation state even if it is not in a low water temperature state, steps 303 and 307 are executed to control the air throttle valve 7 to a closed state, and this program is terminated. do.

The answer to step 304 is negative (No), that is, Ne≧N
e pvc, the process advances to step 305.

It is determined whether the throttle valve opening degree θ〒H is smaller than a predetermined value θ〒1.1 pvc (for example, 20°). The answer to step 305 is affirmative (Yes), that is, N e pvc1≦
Ne < Nepvc, when T w ≧ T IIIPVc and θ〒H θtHPVc hold, that is, even when the engine 1 is in a medium rotation state and is not in a low water temperature state, when the throttle valve 3' is in a low opening state, the above Step 30
Steps 3 and 307 are executed to control the air throttle valve 7 to the closed state, and this program ends.

If the answer to step 305 is negative (No), that is, N ep
vc1≦N a < Nepvc,, Tw≧T vpv
c and θ〒H≧θ〒14pVc, that is, when the engine 1 is in a medium rotation state and is not in a low water temperature state, and the throttle valve 3' is not in a low opening state, the process proceeds to step 306, and the above-mentioned tD set in step 303
It is determined whether or not the Y timer is zero.

If the answer to step 306 is negative (No), that is, the predetermined time tDELAY has not elapsed after the timer was set, step 307 is executed to maintain the closed state of the air throttle valve 7, and this program ends. .

When the answer to step 306 is affirmative (Yes), that is, after the timer is set, the predetermined time tD tag AV has elapsed, the process proceeds to step 308, and the solenoid 22 of the pressure switching valve 22
This program is executed by turning off the power to a to establish communication between the negative pressure chamber 20a of the diaphragm 20 and the venturi section 4, and to make the opening and closing of the air throttle valve 7 directly controlled by the venturi negative pressure Pv. finish.

As mentioned above, the reason for providing a certain waiting time (totbx) when canceling the valve closing control of the air throttle valve 7 is when the conditions for the valve opening control of the air throttle valve 7 are met instantaneously. In addition to preventing the air throttle valve 7 from opening and reliably maintaining its closed state, the air throttle valve 7 is also By opening the valve, the greater the engine load when the valve is opened, the smaller the rate of change in the intake air flow rate becomes, thereby reducing the shock associated with the change in the intake air flow rate.

The answer to step 301 is negative (No), that is, Ne≧N
When e pVco is established, the engine 1 is in a high rotational state, so the process proceeds to step 306.

According to the determination result of step 306, step 30
Execute step 7 or 308 to end this program.

(Effects of the Invention) As detailed above, the present invention allows the air throttle valve to be set to the fully closed position when at least one of the conditions of low rotation of the internal combustion engine or low opening of the throttle valve is satisfied. Therefore, when any of these conditions is satisfied, the air throttle valve is reliably controlled to the closed state, thereby increasing the flow velocity of the intake air near the air throttle valve. When the engine is running at low speeds or when the throttle valve is at a low opening, sudden changes in the intake air flow rate do not occur, resulting in sudden changes in the air-fuel ratio of the air-fuel mixture and the resulting damage to the occupants of the vehicle equipped with the engine. In addition, the injected fuel can be kept in a good atomization state by not reducing the air flow velocity, resulting in stable operation at low rotation speeds of the internal combustion engine and at low throttle valve openings. It has the effect of allowing you to have sex.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a fuel supply control device to which the method of the present invention is applied, FIG. 2 is a plan view of a valve body of an air throttle valve, and FIG. 3 is a flowchart of a control program for a pressure switching valve. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 2a... Intake pipe gathering part, 3'
...Throttle valve, 4...Venturi section (Venturi), 6...Fuel injection valve, 7...Air throttle valve, 7a
... Notch (diaphragm opening), 8... Throttle valve opening (θTH) sensor, 10... Engine rotation speed (Ne)
Sensor, 22...pressure switching valve.

Claims (1)

[Scope of Claims] 1. A fuel injection valve provided upstream of an intake pipe assembly of an internal combustion engine having a plurality of cylinders, and located upstream of a throttle valve whose opening degree is adjusted according to the position of an accelerator pedal. is arranged to supply fuel to the plurality of cylinders, and an air throttle valve is arranged so that its throttle opening faces the discharge port of the fuel injection valve when fully closed, and the air throttle valve is arranged so that the throttle opening faces the discharge port of the fuel injection valve. In the fuel supply control method for an internal combustion engine, the flow rate of intake air near the discharge port of the internal combustion engine is increased, wherein at least one of a predetermined low rotational speed condition of the internal combustion engine and a predetermined low opening condition of the throttle valve is selected. 1. A fuel supply control method for an internal combustion engine, characterized in that the air throttle valve is controlled to a fully closed position when . 2. The air throttle valve is constituted by a pressure-operated valve, and the air throttle valve is configured to apply venturi pressure and atmospheric pressure of a venturi provided between the air throttle valve and the throttle valve to the air throttle valve. 2. A method of controlling fuel supply for an internal combustion engine according to claim 1, wherein the control is performed by a pressure switching valve that switches and introduces fuel.