JPH03279671A - Fuel injection device - Google Patents

Abstract

PURPOSE:To improve responsiveness and obtain a dynamic range enough for use in an automobile by providing a fuel injection valve with which the remaining fuel flow after subtracting a decided quantity for returning through a differential pressure jet from a fuel flow flowing in an upper stream chamber through a metering jet according to adjusted fuel pressure is injected. CONSTITUTION:Fuel pressure corresponding to engine speed A and intake manifold pressure B is set between two opening area setting means, and converted to the adjusted fuel pressure with a third fuel pressure regulator 12. When this adjusted fuel pressure is applied to a lower stream chamber 21 of a fuel injection valve 18, fuel pressure in an upper stream chamber is varied according to this, but fuel flow passing through a differential pressure jet, namely, return flow from the lower stream chamber 21 is controlled to be constant, because pressure difference between both chambers 20, 21 is controlled to be constant. Meanwhile, fuel flow flowing through a metering jet 19 according to the fuel pressure in the upper stream chamber 20 is varied, the remaining fuel flow subtracting the return flow is injected from a discharge port, and fuel pressure of both chambers 20, 21 are balanced each other.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is a pressure cover that controls the amount of fuel injection according to intake manifold pressure and engine speed.
This invention relates to a gas-type fuel injection device.

[Prior art and problems to be solved by the invention] As an example of this type of fuel injection device, the present applicant has disclosed Japanese Patent Application No. 1-3
There is something proposed in 3Q630.

In this device, in a fuel injection valve, an upstream chamber having a fuel discharge port and a downstream chamber that returns fuel to a fuel supply source are separated by a diaphragm, each controlled to a constant pressure, and a differential pressure jet that communicates between the two chambers. A constant flow rate of fuel flows from the upstream chamber to the downstream chamber via the upstream chamber. Then, the fuel at the fuel pressure set according to the intake manifold pressure in the fuel pressure regulator is supplied by the solenoid valve whose opening rate is controlled according to the engine speed.
The fuel pressure is set according to the intake manifold pressure and engine speed, and this is converted to adjusted fuel pressure by a separate fuel pressure regulator.

Since this adjusted fuel pressure is applied to the upstream side of the metering jet, the fuel flow rate passing through the metering jet and flowing into the upstream chamber of the fuel injection valve fluctuates, resulting in a change from the constant flow rate passing through the differential pressure jet described above. The difference in flow rate is injected from the discharge port as the required fuel flow rate by a valve that controls opening and closing of the discharge port in conjunction with the displacement of the diaphragm.

The present invention proposes a fuel injection device with a different basic structure related to this type of device, which is inexpensive to manufacture, has good responsiveness, and has a sufficient dynamic range for use in automobiles. The purpose is to provide an injection device.

[Means to solve the problem]

The fuel injection device according to the present invention includes a first fuel pressure regulator that generates fuel pressure according to intake manifold pressure, and a second fuel pressure regulator that is connected to the first fuel pressure regulator via a fuel passage and generates a constant fuel pressure. , two opening area setting means provided in the fuel passage, at least one of which generates fuel pressure depending on the intake manifold pressure and the engine speed, and adjusting the opening area according to the engine speed; and two opening area setting means that adjust the fuel pressure. an upstream chamber into which fuel flows from the first fuel pressure regulator via a metering jet and is provided with a fuel discharge port; The fuel injection valve includes a downstream chamber that communicates with the fuel injection valve and returns a constant flow rate of fuel, and a diaphragm that partitions the upstream and downstream chambers and interlocks a valve that controls the opening and closing of the discharge port.

[For production]

When the engine is operating, the intake manifold pressure is converted to fuel pressure by the first fuel pressure regulator, fuel at this fuel pressure is supplied to the fuel passage, and the opening area of at least one opening area setting means is adjusted according to the engine speed. A fuel pressure according to the engine speed and intake manifold pressure is set between the two opening area setting means, this is converted to an adjusted fuel pressure by the third fuel pressure regulator, and this adjusted fuel pressure is applied to the downstream chamber of the fuel injection valve. The fuel pressure in the upstream chamber changes accordingly, but since the differential pressure in the compartment is controlled to be constant, the fuel flow rate passing through the differential pressure jet, that is, the return flow rate from the downstream chamber, is controlled to be constant. The fuel flow rate flowing in through the metering jet changes depending on the fuel pressure in the upstream chamber, and the remaining fuel flow rate excluding the return flow rate is injected from the discharge port, thereby balancing the fuel pressures in both chambers.

〔Example〕

A preferred embodiment of the present invention will be described below with reference to FIG.

In the figure, 1 is a fuel pump that pressurizes and delivers fuel from a fuel supply source (not shown), 2 is a first fuel pressure regulator that converts intake manifold pressure into fuel pressure P1 (see Figure 2), and 2 is a first fuel pressure regulator to which intake manifold pressure is applied. a negative pressure chamber 3 that is supplied with fuel, and a fuel chamber 4 that is supplied with fuel from the fuel pump 1.
The fuel chamber 4 is partitioned by a diaphragm 5, and the fuel chamber 4 is provided with a fuel outlet 4a for adjusting the amount of fuel returned to the fuel supply source according to the displacement of the diaphragm 5.

6 is connected to the fuel chamber 4 of the first fuel pressure regulator 2 via a fuel passage 7, and its upstream side is maintained at a constant fuel pressure P2.
This is a diaphragm-type second fuel pressure regulator that controls the fuel pressure so that the fuel pressure regulator 2 is controlled so that the fuel pressure regulator 2 is controlled so that the fuel pressure regulator 2 is controlled so that the fuel pressure regulator 2 is controlled so that the fuel pressure regulator 2 is a diaphragm type second fuel pressure regulator.

9 is a first solenoid valve that is disposed in the fuel passage 7 and controls the opening area of the passage 7 according to the engine speed; IO is a first solenoid valve that is disposed downstream of the first solenoid valve 9 and controls the opening area of the passage 7 according to the engine speed; A second solenoid valve 11 is electrically connected to both solenoid valves 9 and 10 and opens both solenoid valves 9 and 10 when an engine speed signal is input. The pulse signal input from the electronic control unit 16 to both solenoid valves 9 and 10 is the same, but as shown in FIG. When the pulse signal is HIGH, the first solenoid valve 9 is closed and the second solenoid valve IO is open, and when the pulse signal is LOW, the first solenoid valve 9 is open and the second solenoid valve 10 is closed. It is designed to be activated. As shown in FIG. 4, both solenoid valves 9. The duty ratio (pulse signal frequency) of the IO is determined, and the fuel pressure in the fuel passage 7 between both solenoid valves is taken out as the fuel pressure P according to the input signals, the intake manifold pressure and the engine speed. Become.

12 is a third fuel pressure regulator that converts this fuel pressure P3 into an adjusted fuel pressure PI (PI<P3), and includes first and second solenoid valves 9. A first fuel pressure chamber 13 to which fuel pressure P3 of the fuel passage 7 between IO is applied, and a first fuel pressure chamber 13 to which a constant flow rate returned from a fuel injection valve (described later) is introduced and controlled to an adjusted fuel pressure P4 according to fuel pressure P3. The second fuel pressure chamber 14 is partitioned by a diaphragm 15, and the second fuel pressure chamber 1
4 is provided with a fuel outlet 14a that adjusts the return flow rate of fuel according to the displacement of the diaphragm 15, and the diaphragm 15 is pressed toward the first fuel pressure chamber 13 by a spring 16, so that the fuel pressure P3 The rate of change in the adjusted fuel pressure P4 can be reduced (partial pressure).

Reference numeral 18 indicates a fuel injection valve that communicates with the first fuel pressure regulator 2 and the third fuel pressure regulator 12 and controls the amount of fuel injected into the manifold. It is a metering jet that measures the fuel flow rate Q. In the fuel injection valve 18, 20
is a discharge port 20 to which the fuel flow rate Q1 is supplied from the metering jet 19 and can inject the fuel flow rate Q2 into the manifold.
21 is a downstream chamber communicating with the second fuel pressure chamber 14 of the third fuel pressure regulator 12 and to which the adjusted fuel pressure P is applied; 22 is a diaphragm that partitions the upstream chamber 20 and the downstream chamber 21; 23 24 is a differential pressure jet that communicates the upstream chamber 20 and the downstream chamber 21, 24 is a valve that controls opening and closing of the discharge port 20a in conjunction with the diaphragm 22, and 25 is the diaphragm 22.
The fuel pressure P5 in the upstream chamber 20 is controlled so as to be balanced with the sum of the adjusted fuel pressure P in the downstream chamber 2I and the load on the diaphragm 25. Therefore, the differential pressure between the upstream chamber 20 and the downstream chamber 21 (
P5-P, ) is controlled to be constant and the pressure loss of the differential pressure jet 23 is also constant, so the flow rate of the differential pressure jet 23, that is, the fuel flow rate Q returned from the downstream chamber 21 to the second fuel pressure chamber 14.
3 is also controlled to be constant. Further, the fuel flow rate Q passing through the metering jet 19 and flowing into the upstream chamber 20 is the sum of the injection flow rate Q2 and a constant return flow rate Q3.

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

When the engine is running, the second fuel pressure regulator 2 intake manifold pressure is applied and converted to fuel pressure P1 (
(see FIG. 2) is sent to the second fuel pressure regulator 6 via the fuel passage 7, and is controlled by the electronic control unit 11 to the first and second solenoid valves 9, depending on the engine speed. The duty ratio of lO is determined (see FIG. 4) and applied as a pulse signal to each solenoid valve. In this case, when the pulse signal is HIGH, the first solenoid valve 9 is closed and the second solenoid valve 10 is open, and when the pulse signal is LOW, the first solenoid valve 9 is open and the second solenoid valve 10 is closed. Therefore, the fuel pressure P generated between both solenoid valves is large when the engine speed is low, and becomes small when the engine speed is high.

Incidentally, 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 ('duty ratio of the first and second solenoid valves 9 and 10) can be adjusted according to the engine speed, and the obtained fuel pressure P3 is applied to the third fuel pressure regulator. Adjusted fuel pressure P4 at 12
As shown in FIG. 5, it is possible to generate an adjusted fuel pressure P according to the required fuel flow rate. This adjusted fuel pressure P 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.

The adjusted fuel pressure P4 is applied from the second fuel pressure chamber 14 to the downstream chamber 21 of the fuel injection valve 18, but the fuel pressure P4 in the downstream chamber 21 is
4, the flow rate of the differential pressure jet 23 is constant (-
Q3), the fuel pressure P5 in the upstream chamber 21 changes as the adjusted fuel pressure P4 increases or decreases, as shown in FIG.

On the other hand, since the fuel flow rate Q1 passing through the metering jet 19 is determined by the differential pressure (Pl Ps) before and after the metering jet 19, when the adjusted fuel pressure P4 increases by ΔP, Pl, the fuel pressure P5 in the upstream chamber 20 also decreases by ΔP5, and the differential pressure (p , -p5) increases. Then, as shown in FIG. 7, the flow rate Q1 flowing into the upstream chamber 20 via the metering jet 19 increases, but since the flow rate of the differential pressure jet 23 is constant at Q3, the fuel pressure P5 in the upstream chamber 20 increases. The diaphragm 22 rises and is displaced toward the downstream chamber 21, increasing the opening amount of the valve 24, and increasing the fuel injection amount Q2 (-Q, -Q3) from the discharge port 20a. Then, the fuel pressure P in the upstream chamber 20 returns to a predetermined value equal to the sum of the adjusted fuel pressure P4 and the load of the spring 25, and is balanced.

Since this fuel injection amount Q2 corresponds to the adjusted fuel pressure P, it matches the above-mentioned required fuel flow rate.

Moreover, when the adjusted fuel pressure P increases by ΔP4, the upstream chamber 2
Based on FIG. 6, the fuel pressure P5 at 0 also increases by ΔP5, the differential pressure across the metering jet 19 (Pps) decreases, and the fuel flow rate Q1 decreases, so the fuel injection amount Q2 corresponding to the required fuel flow rate also decreases. .

Furthermore, when the intake manifold pressure is minimum, P, =
P, and the adjusted fuel pressure P, = P regardless of the engine speed
, o (see Figure 5), and the differential pressure at this time (P, -P
5), the fuel flow rate becomes QQ3, which becomes Q2-0 (
(See Figure 7).

1 By the way, as shown in Fig. 7, 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), but the fuel flow rate Q1 is returned to the flow rate Q in addition to the injection flow rate Q2. By adding the constant flow rate Q3 in advance, it is possible to extract the portion where the injection flow rate Q2 changes linearly with respect to the differential pressure (P+Ps). Therefore, regarding the flow rate Q1 of the metering jet 19 and the differential pressure across the front and rear (p, -p5), a wide dynamic range sufficient for use in automobiles can be obtained.

As described above, according to this embodiment, the structure is relatively simple, so manufacturing costs can be reduced, and a fuel injection device with good responsiveness and a sufficient dynamic range for automobiles can be realized. can do.

Note that the first and second solenoid valves 9 and 10 each constitute an opening area setting means, but this opening area setting means is not limited to a solenoid valve, and may electrically set the opening area using a stepping motor or the like. It may be adjusted to increase or decrease. Alternatively, either one of the two opening area setting means may be configured as a jet.

Further, although the above-described embodiments relate to a single-point fuel injection system, it goes without saying that the present invention can also be applied to a multi-point fuel injection system. In this case, the fuel injection valve 18 and the metering jet 19 may be arranged for each cylinder and connected to a single first fuel pressure regulator 2 and a single third fuel pressure regulator 12, respectively, and the fuel injection amount Q2 can be equally distributed to each cylinder. It can be distributed to each cylinder.

〔Effect of the invention〕

As described above, the fuel injection device according to the present invention includes a first fuel pressure regulator and an opening area setting means that generate an adjusted fuel pressure according to the required fuel flow rate of the engine, and a fuel injection device that passes through the metering jet and enters the upstream chamber according to the adjusted fuel pressure. Since it is equipped with a fuel injection valve that injects the remaining fuel flow rate excluding the constant flow rate returned via the differential pressure jet out of the inflowing fuel flow rate, the structure is relatively simple and the manufacturing cost can be reduced. In addition, it has the important practical advantages of being highly responsive and having a dynamic range sufficient for use in automobiles.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a fuel injection device according to the present invention, FIG. 2 is a diagram showing the relationship between intake manifold pressure and fuel pressure P1 in the first fuel pressure regulator,
FIG. 3 is a diagram showing a pulse signal, FIG. 4 is a diagram showing the period of the pulse signal depending on the engine speed, and FIG. 5 is a diagram showing the intake manifold pressure and the adjusted fuel pressure P depending on the engine speed. FIG. 6 is a diagram showing the relationship between the adjusted fuel pressure P and the fuel pressure P5 in the upstream chamber, and FIG. 7 is a diagram showing the relationship between the differential pressure (PP5) and each fuel flow rate. 2...First fuel pressure regulator, 6...Second fuel pressure regulator, 7...Fuel passage, 9...First solenoid valve, 10...Second solenoid valve,
12...Third fuel pressure regulator, 18...Fuel injection valve, 19...Metering jet, 20...Upstream chamber, 20a...Discharge port, 21...Downstream chamber , 22
...Diaphragm, 23...Differential pressure jet, 2
4...Valve. 5 familiar river d 1 good for recreational goods d Drop! Fairy tale

Claims (1)

[Claims] A first fuel pressure regulator that generates fuel pressure according to intake manifold pressure, a second fuel pressure regulator that generates a constant fuel pressure, and a fuel passage that connects the first and second fuel pressure regulators. two opening area setting means, at least one of which generates fuel pressure in accordance with the intake manifold pressure and engine rotational speed between which the opening area can be adjusted in accordance with the engine rotational speed; an upstream chamber into which fuel flows from the first fuel pressure regulator via a metering jet and is provided with a fuel outlet, to which the adjusted fuel pressure is applied and the difference is adjusted; a downstream chamber communicating with the upstream chamber via a pressure jet and to which a constant flow rate is returned;
A fuel injection device comprising: a fuel injection valve having a diaphragm that partitions the upstream chamber and the downstream chamber and interlocks a valve that can open and close a discharge port.