JPH0450471A - Fuel jet device - Google Patents

Abstract

PURPOSE:To supply mixed gas of the optimum air-fuel ratio to every cylinder by disposing a third fuel pressure regulator and a solenoid valve at each fuel jet valve, and providing a means to synchronize the action timing of each solenoid valve with an engine rotation signal. CONSTITUTION:While an engine is operating, a valve opening timing of a suction valve of each cylinder is detected based on an engine rotation signal. Each solenoid valve 31 is operated according to ignition procedures corresponding to the detected signal, and fuel is jetted from fuel jet valves 18-1 to 18-4 in order. At this time, the fuel jet quantity at each fuel jet valve 18-1 to 18-4 is controlled based on a regulated fuel pressure at a third fuel pressure regulator 14. It is thus decided by the engine rotation number and intake manifold pressure at each jet timing separately, and the optimum fuel jet quantity can be obtained for each cylinder to be controlled to achieve the optimum air-fuel ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure-balanced fuel injection device that controls a fuel injection amount based on intake manifold pressure and fuel pressure depending on engine speed.

[Conventional technology]

An example of this type of fuel injection device is one proposed by the present applicant in Japanese Patent Application No. 2-77286.

This device will be explained based on FIG. 3. 1 is a fuel pump that pressurizes fuel from a fuel supply source 2 and sends it out; 3 is a fuel pump that converts intake manifold pressure into fuel pressure P1 (4th pump);
(See figure) The first fuel pressure regulator is a negative pressure chamber 4 to which the intake manifold pressure on the downstream side of the throttle valve is applied, and a fuel chamber 5 to which fuel is supplied from the fuel pump l.
The fuel chamber 5 is partitioned by a diaphragm 6, and the fuel chamber 5 is provided with an outlet 5a for returning fuel.

A second fuel pressure regulator 7 is connected to the fuel chamber 5 via a fuel passage 8 and controls its upstream side to a constant fuel pressure Pl (<Pl), and the fuel flowing from the first fuel pressure regulator 3 is supplied to the fuel supply source. 2 will be returned.

10 is a first solenoid valve disposed in the fuel passage 8 and controls the opening area of the passage 8 according to the engine speed; 11 is disposed downstream of the first solenoid valve 10 and controls the opening area of the passage 8 in accordance with the engine speed; A second solenoid valve 12 that controls the opening area according to the engine speed is electrically connected to both solenoid valves 10.11 and controls the opening rate of both solenoid valves 10.11 according to the engine speed signal. The pulse signal output to both solenoid valves 10 and 11 is the same, but as shown in FIG. 5, when this pulse signal is HIGH, the first solenoid valve 10 is closed, the second solenoid valve 11 is open, and when it is LOW, the first solenoid valve IO is open and the second solenoid valve 11 is closed, so that the opening and closing operations are reversed. As shown in the figure, the duty ratio of both solenoid valves 10 and 11 is determined according to the engine speed, and depending on the fuel pressure in the fuel passage 8 between the two solenoid valves, the intake manifold pressure and the engine speed. The resulting fuel pressure is taken out as the fuel pressure P3.

Reference numeral 14 denotes a third fuel pressure regulator that converts the fuel pressure P into an adjusted fuel pressure Pi (<P3), and the third fuel pressure regulator 14 communicates with the fuel passage 8 between the first and second solenoid valves 10.11 to which the fuel pressure P3 is applied. A diaphragm 17 separates the first fuel pressure chamber 15 and a second fuel pressure chamber 16 into which a return flow rate from each fuel injection valve (described later) is introduced and which is controlled to an adjusted fuel pressure P4. The rate of change in the adjusted fuel pressure P4 relative to the fuel pressure P can be set and reduced (partial pressure) by the differential load of the springs.

Numeral 18 is a fuel injection valve that is arranged in each of the four cylinders, for example, and controls the amount of fuel injected into the intake manifold. Numeral 19 is a fuel injection valve that is supplied to each fuel injection valve 18 from a passage on the upstream side of the first fuel pressure regulator 3. These are metering jets that measure the fuel flow rate Q1 at the fuel pressure P1. In the fuel injection valve 18, 21 is an upstream chamber provided with a discharge port 21a to which the fuel flow rate Q1 is supplied from the metering jet 19 and can inject the fuel flow rate Q2 to the manifold, and 22 is the second fuel pressure chamber of the third fuel pressure regulator 14. 16 and is in communication with the adjusted fuel pressure P4
23 is a diaphragm that partitions the upstream chamber 21 and the downstream chamber 22, 24 is a differential pressure jet that communicates the upstream chamber 21 and the downstream chamber 22, and 25 is a valve that controls opening and closing of the discharge port 21a in conjunction with the diaphragm 23. 26 and 27 are springs that press the diaphragm 23, respectively,
The fuel pressure P5 in the upstream chamber 21 is controlled to be balanced with the sum of the adjusted fuel pressure P4 in the downstream chamber 22 and the differential load of the springs 26 and 27 applied to the diaphragm 23.

Therefore, the differential pressure between the upstream chamber 21 and the downstream chamber 22 (P, -P,
) is controlled to be constant, and the pressure loss of the differential pressure jet 24 is also controlled to be constant, so the flow rate of the differential pressure jet 24, that is, the fuel flow rate Q3 returned from the downstream chamber 22 to the second fuel pressure chamber 16 is also controlled to be constant. .

Further, the fuel flow rate Q1 passing through the metering jet 19 and flowing into the upstream chamber 21 is equal to the injection amount Q2 and a constant return flow rate Q3.
It becomes a harmony with

Further, 29 is a throttle for bleed air that is sucked and mixed into each discharge port 21a.

With the above-described configuration, when the intake manifold pressure is applied to the first fuel pressure regulator 3, it is converted to fuel pressure P1 (see FIG. 4) and sent to the second fuel pressure regulator 7 via the fuel passage 8. However, the duty ratio of the first and second solenoid valves 10.11 is determined according to the engine speed (see Fig. 5), and the pulse signal is set to HIGH.
When the solenoid valves 10, 11 are controlled to open and close alternately in accordance with H or LOW, the fuel pressure P generated in the first fuel pressure chamber 15 of the third fuel pressure regulator 14 is large when the engine speed is low, and when the engine speed is low. The larger the number, the smaller it becomes.

The fuel flow rate required by the engine is proportional to the product of the engine speed and the air density of the intake manifold, but the air density can be replaced with pressure, and the pressure difference (p,
-P2), the application rate of Pl and P2 (the duty ratio of the first and second solenoid valves 10.11) can be adjusted according to the engine speed, and the obtained fuel pressure P, By converting the fuel pressure into the adjusted fuel pressure P in the fuel pressure regulator 14, it is possible to generate the adjusted fuel pressure P in accordance with the required fuel flow rate, as shown in FIG. The adjusted fuel pressure P4 increases or decreases according to the increase or decrease in the intake manifold pressure, and its rate of change (slope) decreases or increases according to the increase or decrease in the engine speed.

Then, the adjusted fuel pressure P4 is applied from the second fuel pressure chamber 16 to the downstream chamber 22 of each fuel injection valve 18, and as shown in FIG. 7, the fuel pressure P in the upstream chamber 21 changes in accordance with this fuel pressure P.

On the other hand, since the fuel flow rate Q1 passing through the metering jet 19 is determined by the differential pressure (PP, ) before and after the metering jet 19, when the adjusted fuel pressure P or ΔP4 decreases, the fuel pressure P5 in the upstream chamber 21 also decreases by ΔP.
5 decreases, and the differential pressure (P, Ps) increases.

Then, as shown in FIG. 8, the flow rate Q1 flowing into the upstream chamber 21 via the metering shet 19 increases, but since the flow rate of the differential pressure shet 24 is constant at Q3, the upstream chamber 21
The fuel pressure P5 increases and the fuel injection amount Q from the discharge port 21a increases.
, (=Q, -Q,) increases. The fuel pressure P in the upstream chamber 21 is balanced with the sum of the adjusted fuel pressure P and the differential loads of the springs 26 and 27.

Further, when the adjusted fuel pressure P4 increases by ΔP, the differential pressure across the metering jet 19 (Pl pi) decreases, and the fuel flow rate Q1 and fuel injection amount Q2 decrease.

In this way, the fuel injection amount Q2 corresponds to the adjusted fuel pressure P4, so it matches the above-mentioned required fuel flow rate.

Further, the fuel flow rate Q1 of the metering jet 19 changes in proportion to the square root of the differential pressure across the front and rear (P, -P5) as shown in FIG. 8, but the fuel flow rate Q is returned in addition to the injection flow rate Q2. By adding the constant flow rate Q3 in advance, it is possible to extract a portion where the injection flow rate Q2 changes linearly with respect to the differential pressure (P, -P5). Therefore, regarding the flow rate Q of the metering jet 19 and the differential pressure (pi - P5), it is possible to obtain a wide dynamic range sufficient for use in automobiles.

By the way, in a four-cycle engine, if the fuel Q2 is injected from the fuel injection valve 18 once for every two rotations of the engine, the fuel Q2 will be injected once every 1 intake strokes for each cylinder.

[Problem to be solved by the invention]

However, the above-mentioned fuel injection device uses a pair of solenoid valves 10 and 11 and a negative third fuel pressure regulator 14 to set the fuel injection amount Q2 of all the fuel injection valves 18 and perform simultaneous injection. However, since the opening timing of the intake valve of each cylinder is different, it does not match the injection timing.

For example, during acceleration, when both solenoid valves 10.11 are operated and controlled by the acceleration signal and the adjusted fuel pressure P4 is inputted to each fuel injection valve 18, the increase in the amount of fuel Q2 supplied to the four cylinders is as follows: Until one cycle, that is, each of the four cylinders explodes once, they are equal, and in the next cycle, the amount of fuel Q2 can be increased from the first time, but the fuel Q2 itself supplied to each cylinder is still equal to each other. do not have. For this reason, it cannot be said that the optimum injection amount is supplied to each cylinder at the optimum injection timing during acceleration, and the air-fuel ratio of each air-fuel mixture is not optimal.

In view of these problems, it is an object of the present invention to provide a fuel injection device of this type that employs a sequential injection method so that an optimal air-fuel ratio can be obtained for each cylinder. .

[Means to solve the problem]

The fuel injection device according to the present invention has an upstream opening in a fuel passage connected to a first fuel pressure regulator that generates a fuel pressure according to intake manifold pressure and a second fuel pressure regulator that generates a constant pressure lower than this fuel pressure on the downstream side. A solenoid valve that alternately controls the opening and closing of the opening is controlled to open and close according to the engine speed, thereby generating fuel pressure between both openings that corresponds to the intake manifold pressure and the engine speed, and this fuel pressure is transferred to the third fuel pressure regulator. In a fuel injection device that converts fuel pressure into adjusted fuel pressure and injects a fuel flow rate corresponding to the adjusted fuel pressure from fuel injection valves provided in each cylinder, each fuel injection valve is equipped with a solenoid valve and a third fuel pressure regulator. and a means for synchronizing the operating timing of each solenoid valve with the engine rotation signal,
The injection timing and fuel injection amount of each fuel injection valve can be controlled for each cylinder.

[For production]

When the engine is operating, the opening timing of the intake valve of each cylinder is detected based on the engine rotation signal, and in response to this, each solenoid valve is operated according to the ignition order, and fuel is sequentially injected from each fuel injection valve. Furthermore, the amount of fuel injected by each fuel injection valve is controlled according to the adjusted fuel pressure of each third fuel pressure regulator, so it is individually determined by the engine speed and intake manifold pressure at each injection timing, and the amount of fuel injected into each cylinder is The optimal fuel injection amount can be obtained for each time, and the air-fuel ratio can be controlled to the optimal air-fuel ratio.

〔Example〕

Hereinafter, a preferred embodiment of the present invention will be described based on FIGS. 1 and 2, and the same reference numerals will be used for the same parts as in the above-mentioned prior art, and the explanation thereof will be omitted.

In FIG. 1, regarding the fuel injection valves 18-1.18-2.18-3.18-4 respectively arranged in the four cylinders,
A third fuel pressure regulator 14 is connected to each of the first fuel pressure regulators 14, and a fuel passage 8 connecting the first fuel pressure regulator 3 and the second fuel pressure regulator 7 is branched and communicated with each first fuel pressure chamber 15, respectively. At the same time, a single solenoid valve 31 for applying a fuel pressure P depending on the engine speed and intake manifold pressure to the first fuel pressure chamber 15 is provided.

FIG. 2 is a sectional view of a main part of an example of the solenoid valve 31. In the figure, 32 is a pressure adjustment chamber formed in the valve body 31a, which is connected to the fuel passage 8 on the first fuel pressure regulator 3 side. An upstream opening 32a communicating with the fuel passage 8 on the second fuel pressure regulator 7 side, and a downstream opening 32b communicating with the fuel passage 8 on the second fuel pressure regulator 7 side.
Intermediate openings 32c communicating with the first fuel pressure chambers 1-5 are respectively formed. Note that this pressure adjustment chamber 32 may be formed in the fuel passage 8 itself, and FIG. 1 shows this.

33 is an excitation coil; 34 is a slidable plunger biased toward the pressure adjustment chamber 32 by a spring 35;
Reference numeral 36 designates first and second valves 36a and 36b whose one end abuts the tip of the plunger 34 and is loosely inserted into the downstream opening 32b, and whose other end is located within the pressure adjustment chamber 32.
37 is a first valve seat formed around the upstream opening 32a on which the first valve 36a can be seated; 38 is a first valve seat 3;
7, a second valve seat 39 is formed around the downstream opening 32b, and on which the second valve 36b can be seated; It's a small spring.

When the excitation coil 33 is not energized, the control valve 36 is configured so that the first valve 36a is connected to the first valve seat 37.
The second valve 36b opens the downstream opening 32b and closes the upstream opening 32a, thereby closing the intermediate opening 32.
It becomes in communication with c (the state shown in Fig. 2). Further, when the excitation coil 33 is energized, the plunger 34 is attracted and the control valve 36 also operates in the same direction due to the spring load of the spring 39, so that the second valve 36b moves toward the second valve seat 38.
At the same time, the first valve 36a opens the upstream opening 32a and closes the downstream opening 32b.
It becomes in communication with c.

Moreover, when the pulse signal shown in FIG. 5 outputted from the electronic control unit 12 is HIGH, the excitation coil 33 is controlled to be cut off, and when it is LOW, it is controlled to be energized.

In addition, the electronic control unit 12 discriminates cylinders using a known method based on an engine rotation signal from a crank angle sensor (or a contact, a reed switch, etc.), and determines the timing according to the opening timing of the intake valve of each cylinder. 5
Application timing of the pulse signal shown in the figure, that is, solenoid valve 3
1 is provided with means for determining the operation start timing of each solenoid valve 31 and outputting the same to each solenoid valve 31.

Since this embodiment is configured as described above, when the engine is operating, the electronic control unit 12 detects the opening timing of the intake valve of each cylinder based on the engine rotation signal, and the ignition is started according to this valve opening timing. According to the order, the electronic control unit 12 sequentially outputs the pulse signals shown in FIG. 5 to each solenoid valve 31.

The duty ratio of the pulse signal is determined by the engine speed as shown in Figure 5, and the duty ratio of the solenoid valve 3 is determined by the engine speed.
1, when the pulse signal is HIGH, the first valve 36a closes the upstream opening 32a of the fuel passage 8, the second valve 36b opens the downstream opening 32b, and the L
At the time of OW, the upstream opening 32a is open and the downstream opening 32b is closed, and the upstream opening 32 is opened according to the set duty ratio.
The control valve 36 is reversely operated so that the downstream opening 32b and the downstream opening 32b are alternately opened and closed. Accordingly, a fuel pressure P3 is set between the openings 32a and 32b depending on the engine speed and the intake manifold pressure. In this way, the first fuel pressure chamber 1 of the third fuel pressure regulator 14
The fuel pressure P applied to the engine 5 is large when the engine speed is low, and becomes small when the engine speed is high.

This fuel pressure P is adjusted by the third fuel pressure regulator 14.
4 and is controlled in the same manner as in the prior art described above to obtain the fuel injection amount Q2 shown in FIG. 8 from the fuel injection valve 18. Moreover, each fuel injection valve 1B-1, 18-2, 18-3
, 18-4 sequentially injects the fuel Q2 according to the opening timing of the intake valve of each cylinder.
The optimal fuel injection amount Q2 is individually determined according to the engine rotation speed and intake manifold pressure at each injection time.

Therefore, for example, during acceleration, the fuel injection amount from each fuel injection valve can be increased and supplied sequentially according to the adjusted fuel pressure P4 from the cylinder that explodes first to the cylinders that explode sequentially. Fine-grained fuel injection amount control is possible at each time. Therefore, an air-fuel mixture with an optimal air-fuel ratio can be obtained for each cylinder, and harmful components in exhaust gas can also be reduced.

As described above, according to this embodiment, the sequential injection method is adopted, and the fuel injection valves 1B-1, 18-
The injection timing and fuel injection amount Q2 of Nos. 2, 18-3, and 18-4 can be independently and appropriately controlled by the electronic control unit 12, and an air-fuel mixture with an optimal air-fuel ratio can be supplied to each cylinder. Also, exhaust gas components are improved.

Note that in this embodiment, a single solenoid valve 31
However, it may be controlled by the first and second solenoid valves 10.11 as in the prior art described above.

Further, although the above-described embodiment relates to a closed-cylinder engine, it goes without saying that the number of cylinders is not limited to this.

〔Effect of the invention〕

As described above, in the fuel injection device according to the present invention, the third fuel pressure regulator and the solenoid valve are arranged for each fuel injection valve, and means for synchronizing the operating timing of each solenoid valve with the engine rotation signal is provided. The fuel injection timing and injection amount of the fuel injection valve can be individually and appropriately controlled for each cylinder, and a mixture with an optimal air-fuel ratio can be supplied to each cylinder.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a fuel injection device according to the present invention, FIG. 2 is a sectional view of a main part of a solenoid valve, FIG. 3 is a schematic diagram of a fuel injection device according to the prior art, and FIG. Figure 5 is a diagram showing the relationship between intake manifold pressure and fuel pressure P1 in a fuel pressure regulator, Figure 5 is a diagram showing the period of a pulse signal according to engine speed, and Figure 6 is a diagram showing the relationship between intake manifold pressure and engine speed. Figure 7 shows the adjusted fuel pressure P4 and the fuel pressure P in the upstream chamber.
FIG. 8 is a diagram showing the relationship between the differential pressure (P-Ps) and each fuel flow rate. 3...First fuel pressure regulator, 7...Second fuel pressure regulator, 8...Fuel passage, 14...Third fuel pressure regulator, 18.18-1.18-2.18-
3.18-4... Fuel injection valve, 31... Solenoid valve, 32a... Upstream opening, 32b...
Downstream opening. Fig. 4 Intake manifold hole μ゛Pressure rotation speed 10 less medium near (ms) Fig. 16 RnEpbo! Off diagram 8 Figure tIl11 Director I-1 Catty P4 Differential pressure (R-Ps)

Claims (1)

[Scope of Claims] An upstream opening and a downstream opening in a fuel passage that connect a first fuel pressure regulator that generates fuel pressure according to intake manifold pressure and a second fuel pressure regulator that generates a constant fuel pressure, A solenoid valve that alternately opens and closes is controlled to open and close according to the engine speed, and a fuel pressure corresponding to the intake manifold pressure and the engine speed is generated between the two openings, and the fuel pressure is adjusted to the fuel pressure by a third fuel pressure regulator. In a fuel injection device in which a fuel flow rate corresponding to the adjusted fuel pressure is injected from a fuel injection valve provided in each cylinder, each fuel injection valve is provided with a solenoid valve and a third fuel pressure regulator, respectively. In addition, the fuel is provided with means for synchronizing the operating timing of each solenoid valve with an engine rotation signal, so that the injection timing and fuel injection amount of each fuel injection valve can be controlled for each cylinder. Injection device.