JP2001099027A - Pressure regulator of and electronic controlled of fuel injection device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure regulator which promotes atomization of fuel vapor in a low load area of an engine such as starting and idling, reduces a load applied to a fuel pump in a high load area of the engine, and reduces a flow amount size of the fuel pump. SOLUTION: A fuel pressure chamber in which fuel pressure in a fuel piping 3 is introduced and a reference pressure chamber 23 are determined by a diaphragm 22. A pressure regulator 8 is so operated that, when the fuel pressure is less than a threshold value, a return piping 26 is opened for returning the fuel to a fuel tank. In such a pressure regulator 8, an orifice 30 is arranged on the return piping 26. The fuel pressure is increased with the less fuel flow amount required by an engine and much amount of returned fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure regulator for an internal combustion engine and an electronically controlled fuel injection device, and more particularly, to a mechanical pressure regulator for adjusting the pressure of fuel sent to a fuel injection valve, and a fuel injection system. The present invention relates to an electronically controlled fuel injection device that controls a fuel injection amount by controlling a valve opening time.

[0002]

2. Description of the Related Art Conventionally, the pressure of fuel supplied to a fuel injection valve (hereinafter referred to as fuel pressure) is adjusted by a mechanical pressure regulator in order to keep the injection amount per unit time of the fuel injection valve constant. There is known an electronically controlled fuel injection device configured to supply a required amount of fuel to an engine by setting a valve opening time corresponding to a required fuel amount of the engine (see Japanese Patent Application Laid-Open No. 6-249013). .

[0003] The mechanical pressure regulator is
When the fuel pressure is higher than a set pressure, a valve body that closes a return passage for returning fuel to the fuel tank is lifted to return excess fuel to the fuel tank.

[0004]

By the way, when the engine pressure is increased at the start of the engine when the engine temperature is low and the fuel vaporization is deteriorated, atomization of the fuel spray can be achieved. For example, if a configuration is used in which two pressure regulators are switched as disclosed in Japanese Patent Application Laid-Open No. 6-249013, the set pressure in each pressure regulator is made different, The fuel pressure may be adjusted by the pressure regulator having the higher set pressure.

However, in the case where two pressure regulators are provided as described above and are used by switching between them, one pressure regulator and an extra valve for switching are required, so that the layout of the fuel pipe is reduced. There is a problem that the structure becomes complicated, and the weight and cost increase.

Further, in the case of a configuration in which the pressure regulator is switched between the start and the normal operation, although the effect of improving the startability and the exhaust property by atomizing the fuel is obtained at the start, the two pressure regulators are operated during the normal operation. There is a problem in that the advantages provided by the configuration cannot be enjoyed, and the current consumption and operating noise of the fuel pump, which are problems during normal operation, cannot be improved.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. A mechanical pressure which can independently reduce the fuel pressure as the load becomes higher while adjusting to a high fuel pressure at the time of starting or in a low load region including idling. An object of the present invention is to provide a regulator, thereby reducing current consumption and operating noise during normal operation while improving startability and exhaust properties at start.

It is another object of the present invention to provide an electronically controlled fuel injection device capable of injecting a required fuel amount into an engine in response to a change in fuel pressure by the pressure regulator.

[0009]

According to the first aspect of the present invention, the pressure of fuel sent to a fuel injection valve of an internal combustion engine is adjusted by controlling the amount of fuel returned to a fuel tank via a return passage. In the mechanical pressure regulator described above, the orifice provided in the return passage increases the fuel pressure with respect to an increase in the flow rate of the fuel returned to the fuel tank through the return passage.

With this configuration, the fuel obtained by removing the amount of fuel supplied to the engine from the discharge amount from the fuel pump is surplus fuel, and the return passage is opened to return the surplus fuel to the fuel tank. . Here, the provision of the orifice in the return passage increases the fuel pressure at low load when the required fuel amount of the engine is small and the excess fuel (return fuel flow rate) is large, and conversely, the required fuel amount of the engine is large and the excess fuel At a high load when the fuel (return fuel flow rate) decreases, the fuel pressure relatively decreases.

According to a second aspect of the present invention, there is provided an electronically controlled fuel injection system for an internal combustion engine, wherein an amount of fuel injected by the fuel injection valve is controlled by controlling a valve opening time of the fuel injection valve. In addition to the regulator, a fuel pressure sensor for detecting the pressure of the fuel sent to the fuel injection valve is provided, and the valve opening time of the fuel injection valve is corrected in accordance with the fuel pressure detected by the fuel pressure sensor.

According to this configuration, the pressure regulator does not control the fuel pressure to be constant, but adjusts the fuel pressure to be higher with an increase in the return fuel flow rate (excess fuel). The injection amount per time will change. Therefore, by measuring the actual fuel pressure, the change in the injection amount per unit time is detected,
This is to correct the valve opening time required to inject the required fuel amount.

According to the third aspect of the present invention, the reference valve opening time corresponding to the required fuel amount of the engine is calculated in accordance with the case where the fuel pressure is the reference pressure, while the fuel pressure detected by the fuel pressure sensor is calculated. Set the correction coefficient according to the pressure of
The final valve opening time is set by correcting the reference valve opening time with the correction coefficient.

According to this configuration, when the fuel pressure is adjusted to a constant reference pressure, in other words, on the assumption that the injection amount per unit time is a constant reference amount, the required fuel amount is injected. The valve opening time is determined as a reference valve opening time. Here, the actual fuel pressure changes according to the return fuel flow rate due to the action of the pressure regulator.
In order to correct the difference between the injection amount per unit time assumed when the actual fuel pressure was detected by the fuel pressure sensor and the reference valve opening time was obtained and the injection amount per unit time in the actual fuel pressure state, A correction coefficient is set according to the actual fuel pressure, and the reference valve opening time is corrected with the correction coefficient.

[0015]

According to the first aspect of the present invention, the fuel pressure increases in a low load range, and particularly, the startability and the exhaust properties at the start can be improved by atomizing the fuel at the start, while reducing the required fuel amount. At a high load, the load on the fuel pump is reduced by lowering the fuel pressure. Therefore, the discharge flow rate (flow rate size) required for the fuel pump can be reduced, thereby reducing the current consumption and operation noise of the fuel pump. There is an effect that it can be reduced. Further, since the above operation can be realized only by the single pressure regulator, there is an effect that the layout of the fuel system is not complicated and the weight and cost are not significantly increased.

According to the second aspect of the invention, when the fuel pressure adjusted by the pressure regulator is changed,
There is an effect that the required fuel amount of the engine can be injected without excess or deficiency.

According to the third aspect of the present invention, the reference valve opening time corresponding to the reference fuel pressure state is corrected to the valve opening time corresponding to the fuel pressure at that time so as to correspond to the difference in the actual fuel pressure with respect to the reference fuel pressure. Thus, the required fuel amount can be reliably injected.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an electronically controlled fuel injection device for a vehicle internal combustion engine. One end of a fuel pipe 3 is connected to a discharge port of a fuel pump 2 built in a fuel tank 1. At the other end, fuel gallery 4
Is connected.

The fuel gallery 4 is connected to a fuel injection valve 5 which is provided for each cylinder and injects fuel into an intake port (upstream of the intake valve) of each cylinder. The fuel injection valve 5
Is an electromagnetic fuel injection valve that is energized to open, and is deenergized to close, and the valve opening time and valve opening timing are controlled by an injection pulse signal sent from the control unit 6. .

The control unit 6 receives detection signals from an air flow meter 15 for detecting the intake air flow rate of the engine, a crank angle sensor 16 for detecting the crank angle of the engine, and the like. The valve opening time and the valve opening timing are determined, and an injection pulse signal is output to the fuel injection valve 5 according to the determination.

A fuel filter 7 is interposed in the fuel pipe 3 in the fuel tank 1, and the fuel filtered by the fuel filter 7 is supplied to a pressure regulator 8 which is also interposed in the fuel pipe 3 in the fuel tank 1. And the fuel pressure is adjusted, and sent to each fuel injection valve 5 via the fuel gallery 4.

As shown in FIG. 2, the pressure regulator 8 is a mechanical pressure regulator using a diaphragm. In FIG. 2, a cylindrical space in a case 21 is vertically divided into a reference pressure chamber 23 and a fuel pressure chamber 24 by a disk-shaped diaphragm 22.

A gas at a reference pressure is confined in the reference pressure chamber 23, while a fuel pressure introduction pipe 25 having one end connected to the fuel pipe 3 is connected to an opening in the peripheral wall of the fuel pressure chamber 24. The fuel pressure in the fuel pipe 3 is introduced through the fuel pressure introducing pipe 25, and the diaphragm 22 receives the fuel pressure and bends upwardly in the drawing.

In the fuel pressure chamber 24, the other end of the return pipe 26, one end of which is opened into the fuel tank 1, has a case 21 with the center axis of the diaphragm 22 as the axial direction.
, And is opened directly below the diaphragm 22, and a valve seat 27 is formed in the opening.

On the other hand, a ball valve 28 is supported on the lower surface of the center of the diaphragm 22. When the ball valve 28 is seated on the valve seat 27, the return pipe 26 is closed, and the upward deflection of the diaphragm 22 is caused. Then, when the ball valve 28 is lifted, the return pipe 26 is opened.

Reference numeral 29 denotes a coil which is compressed and interposed between the ceiling wall of the case 21 and the upper surface of the diaphragm 22 in the reference pressure chamber 23 to urge the ball valve 28 in the seating direction. It is a spring.

In the above configuration, when the fuel pressure in the fuel pipe 3 exceeds a threshold pressure determined by the pressure in the reference pressure chamber 23 and the urging force of the coil spring 28,
The diaphragm 22 is bent upward, the ball valve 28 is lifted from the valve seat 27, the return pipe 26 (return passage) is opened, and fuel is returned into the fuel tank 1 via the return pipe 26. It acts to lower the fuel pressure.

Here, the valve seat 27 of the return pipe 26
An orifice 30 is provided at a position near the downstream, and the orifice 3
By selecting a diameter of 0, as shown in FIG. 3, the fuel pressure gradually increases with an increase in the flow rate of return fuel returned into the fuel tank 1 via the return pipe 26 (return passage).

That is, as shown in FIG. 4, in a low load region where the required fuel flow rate Qe of the engine is smaller than the discharge flow rate Qp of the fuel pump 2, the excess fuel increases and the return fuel flow rate Ql increases, and the orifice The fuel pressure P is adjusted to be higher as the required fuel flow rate Qe is smaller by 30, while the required fuel flow rate Qe of the engine is higher than the discharge flow rate Qp of the fuel pump 2.
In a high-load region where there is a large amount of excess fuel, the amount of surplus fuel is reduced and the return fuel flow rate Ql is reduced.

Here, the discharge flow rate Qp of the fuel pump 2 and
From the required fuel flow Qe of the engine, the return fuel flow Ql
Is obtained as Ql = Qp−Qe, and the fuel pressure P adjusted by the pressure regulator 8 is represented by Pi
Then, P = Pi + Q1 × K is obtained. In the above equation, K is a constant determined by the diameter of the orifice 30.

According to the pressure regulator 8 having the above-described structure, the fuel is injected at a high fuel pressure during a low load operation such as at the time of starting or idling, thereby atomizing the fuel spray, thereby improving the combustion stability. As a result, the exhaust characteristics are improved, and the startability is improved at the start.

On the other hand, in the high load region where the required fuel flow rate is large, the load on the fuel pump 2 is reduced by lowering the fuel pressure. Can be reduced.

If the flow size of the fuel pump 2 can be reduced, the current consumption of the fuel pump 2 can be reduced.
The fuel efficiency of the vehicle can be improved, and the noise of the fuel pump 2 can be reduced. Furthermore, by reducing the flow rate size of the fuel pump 2, the size of the alternator and the size of the battery can be reduced at the same time, and the noise of the fuel pump 2 can be reduced, so that the sound insulating material can be reduced. Cost reduction is achieved.

The fuel injection valve 5 may be configured to inject fuel directly into the cylinder of each cylinder. However,
If the fuel injection valve 5 is configured to inject fuel directly into the cylinder and perform a compression stroke injection, a certain high pressure is required. Therefore, the fuel pressure supplied to the high pressure fuel pump is It is preferable that the pressure be adjusted by the pressure regulator 8.

Further, a configuration may be adopted in which the suction negative pressure of the engine is led to the reference pressure chamber 23 of the pressure regulator 8. By the way, the fuel pressure sent to the fuel injection valve 5 by the pressure regulator 8 changes, so that the injection amount per unit time in the fuel injection valve 5 changes, so that the valve opening time of the fuel injection valve 5 (the injection pulse signal In order to inject the required fuel amount of the engine by controlling the pulse width), a fuel pressure sensor 10 is provided at the downstream end of the fuel gallery 4, and the control unit 6 controls the fuel pressure sensor 1
The opening time (injection pulse width) of the fuel injection valve 5 is controlled based on the fuel pressure detected at 0.

FIG. 5 is a flowchart showing details of the valve opening time control. First, in S1, the engine rotation speed is calculated based on the detection signal from the crank angle sensor 16, and the intake air flow rate by the air flow meter 15 is calculated. Read the air flow detection result.

In the next S2, the fuel pressure sensor 10
Read the detected fuel pressure. In S3, a correction coefficient α for correcting the injection pulse width Ti is set according to the fuel pressure read in S2. The correction coefficient α is
Corresponding to an increase in the injection amount per unit time as the fuel pressure increases, a smaller value is set as the fuel pressure increases.

In step S4, a reference injection pulse is set as a reference valve opening time required to inject a required fuel amount corresponding to the intake air flow rate, the rotation speed and the target air-fuel ratio of the engine at a preset reference fuel pressure. The width Tib is calculated.

In step S5, the reference injection pulse width Tib is corrected by the correction coefficient α to inject the required fuel amount in accordance with the difference between the reference fuel pressure and the fuel pressure at that time. The pulse width Ti is determined.

Ti = Tib × α An injection pulse signal having the injection pulse width Ti is output to each fuel injection valve 5 at the timing of, for example, the intake stroke of each cylinder, so that a required amount of fuel is supplied to each cylinder. Is injected to form a mixture having the target air-fuel ratio.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration of an electronically controlled fuel injection device for an internal combustion engine according to an embodiment.

FIG. 2 is a longitudinal sectional view showing a pressure regulator according to the embodiment.

FIG. 3 is a diagram showing a correlation between a fuel pressure and a return fuel flow rate in the pressure regulator according to the embodiment.

FIG. 4 is a diagram showing characteristics of fuel pressure with respect to an engine load and an engine required fuel flow rate in the pressure regulator of the embodiment.

FIG. 5 shows an injection pulse width (valve opening time) in the embodiment.
4 is a flowchart showing the control of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel tank 2 ... Fuel pump 3 ... Fuel piping 4 ... Fuel gallery 5 ... Fuel injection valve 6 ... Control unit 7 ... Fuel filter 8 ... Pressure regulator 22 ... Diaphragm 23 ... Reference pressure chamber 24 ... Fuel pressure chamber 25 ... Fuel pressure introduction pipe 26 ... return piping 27 ... valve seat 28 ... ball valve 29 ... coil spring 30 ... orifice

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 55/00 F02M 55/00 B 55/02 350 55/02 350E 350B 69/00 340 69/00 340P F Term (Reference) 3G066 AA01 AB02 AD10 BA03 BA12 BA14 BA17 BA22 BA23 CB03 CB11 CB15 CB16 CC06U CD02 CD25 CD26 CE13 CE22 DA01 DB01 DB07 DC05 DC09 DC11 DC18 3G301 HA01 HA06 JA02 JA21 JA23 JA37 KA01 KA07 LB06 MA01 MA03 NA03 NC01 PB08Z PE01Z PE03Z

Claims (3)

[Claims] 1. A mechanical pressure regulator for adjusting the pressure of fuel sent to a fuel injection valve of an internal combustion engine by controlling an amount of fuel returned to a fuel tank via a return passage. A pressure regulator for the internal combustion engine, wherein the pressure of the fuel increases with an increase in the flow rate of the fuel returned to the fuel tank via the return passage. 2. An electronically controlled fuel injection device for an internal combustion engine for controlling a fuel injection amount of the fuel injection valve by controlling a valve opening time of the fuel injection valve. An electronically controlled fuel injection device for an internal combustion engine, comprising: a fuel pressure sensor for detecting a pressure of fuel sent to an injection valve, wherein the valve opening time is corrected according to a fuel pressure detected by the fuel pressure sensor. . And calculating a reference valve opening time corresponding to a required fuel amount of the engine in accordance with a case where the fuel pressure is a reference pressure, and correcting the reference valve opening time in accordance with the fuel pressure detected by the fuel pressure sensor. 3. The electronically controlled fuel injection device for an internal combustion engine according to claim 2, wherein a coefficient is set, and the reference valve opening time is corrected by the correction coefficient to set a final valve opening time.