JPH0826834B2 - Fuel injector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pressure-balanced fuel injection device in which the fuel injection amount is controlled according to the intake manifold pressure and the engine speed.

[Problems to be Solved by Prior Art and Invention]

As an example of this type of fuel injection device, there is one proposed by the present applicant in Japanese Patent Application No. 1-330630.

In this device, in a fuel injection valve, an upstream chamber having a fuel discharge port and a downstream chamber for returning fuel to a fuel supply source are partitioned by a diaphragm, each of which is controlled to a constant pressure, and a differential pressure communicating between both chambers. A constant fuel flow rate flows from the upstream chamber to the downstream chamber via the jet. Then, in the fuel pressure regulator, the fuel of the fuel pressure set according to the intake manifold pressure is set to the fuel pressure corresponding to the intake manifold pressure and the engine speed by the solenoid valve whose valve opening rate is controlled according to the engine speed. , This is converted into adjusted fuel pressure by another fuel pressure regulator.

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

The present invention proposes a fuel injection device having another type of basic structure, which is related to this type of device, and has a low manufacturing cost, good responsiveness, and a fuel having a sufficient dynamic range for automobiles. An object is to provide an injection device.

[Means for solving the problem]

The fuel injection device according to the present invention includes a first fuel pressure regulator that generates a fuel pressure according to the 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 for generating a fuel pressure according to the intake manifold pressure and the engine speed from between the two opening area setting means for adjusting the opening area according to the engine speed, and this fuel pressure A third fuel pressure regulator that converts the fuel pressure, an upstream chamber where fuel flows from the first fuel pressure regulator through a metering jet and a fuel discharge port, and an upstream chamber where a regulated fuel pressure is applied and a differential pressure jet A downstream chamber that communicates with and returns a constant fuel flow rate, and separates the upstream chamber and the downstream chamber A fuel injection valve having a diaphragm that interlocks with a valve that controls opening and closing of the discharge port;
It has.

[Work]

During engine operation, the intake manifold pressure is converted into fuel pressure by the first fuel pressure regulator, fuel of 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 the intake manifold pressure is set between the two opening area setting means, and this is converted into a regulated fuel pressure by the third fuel pressure regulator, and this regulated fuel pressure is applied to the downstream chamber of the fuel injection valve. The fuel pressure in the upstream chamber also changes in response to this, but since the differential pressure between the two chambers 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 flow rate of fuel flowing through the metering jet changes according to the fuel pressure in the upstream chamber, and the remaining fuel flow rate excluding the return flow rate is injected from the discharge port. Is, the fuel pressure in both chambers are balanced.

〔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 sends out fuel from a fuel supply source (not shown), 2 is a first fuel pressure regulator that converts intake manifold pressure to fuel pressure P ₁ (see FIG. 2), and intake manifold pressure is Applied negative pressure chamber 3 and fuel chamber 4 to which fuel is supplied from the fuel pump 1.
Are partitioned by a diaphragm 5, and the fuel chamber 4 is provided with a fuel outlet 4a for adjusting the amount of fuel to be returned to the fuel supply source according to the displacement of the diaphragm 5. 6
Is a diaphragm-type second fuel pressure regulator connected to the fuel chamber 4 of the first fuel pressure regulator 2 via the fuel passage 7 and controlling the upstream side thereof to a constant fuel pressure P ₂ (<P ₁ ). The fuel flowing from the regulator 2 is returned to the fuel supply source.

9 is a first solenoid valve disposed in the fuel passage 7 for controlling the opening area of the passage 7 according to the engine speed, and 10 is disposed downstream of the first solenoid valve 9 in the fuel passage 7. The second solenoid valve that controls the opening area of the solenoid valve according to the engine speed, 11 is electrically connected to both solenoid valves 9 and 10, and the engine speed signal is input to open both solenoid valves 9 and 10. It is an electronic control unit (ECU) that changes the rate, and the pulse signals input from the electronic control unit 11 to both solenoid valves 9 and 10 are the same, but as shown in FIG. When the pulse signal is LOW, the first solenoid valve 9 is closed and the second solenoid valve 9 is open. When the pulse signal is LOW, the first solenoid valve 9 is open and the second solenoid valve 10 is closed. It is adapted to be actuated. Then, as shown in FIG. 4, the duty ratio (frequency of the pulse signal) of both solenoid valves, 9 and 10 is determined according to the engine speed, and the fuel pressure in the fuel passage 7 between both solenoid valves is input. It will be taken out as the fuel pressure P ₃ according to the intake manifold pressure which is a signal and the engine speed.

A third fuel pressure regulator 12 converts the fuel pressure P ₃ into a regulated fuel pressure P ₄ (P ₄ <P ₃ ), and the fuel pressure P _{3 in} the fuel passage 7 between the first and second solenoid valves 9 and 10 is The first fuel pressure chamber 13 to be applied and the second fuel pressure chamber 14 in which a constant return flow rate returned from a fuel injection valve described later is introduced and is controlled to the adjusted fuel pressure P ₄ according to the fuel pressure P ₃ , the diaphragm 15 The second fuel pressure chamber 14 is divided by the fuel outlet 14a in which the fuel return flow rate is adjusted according to the displacement of the diaphragm 15.
And the diaphragm 15 is elastically pressed toward the first fuel pressure chamber 13 by the spring 16, which causes the fuel pressure P ₃
It is possible to reduce (partial pressure) the change rate of the adjusted fuel pressure P ₄ with respect to.

Reference numeral 18 denotes a fuel injection valve which communicates with the first fuel pressure regulator 2 and the third fuel pressure regulator 12 and whose fuel injection amount to the manifold is controlled. 19 denotes a fuel injection valve 18 from the fuel chamber 4 of the first fuel pressure regulator 2. A metering jet that measures the fuel flow rate Q ₁ . In the fuel injection valve 18, 20 is an upstream chamber provided with a fuel flow rate Q ₁ from a metering jet 19 and having a discharge port 20a capable of injecting the fuel flow rate Q ₂ into a 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 ₄ is applied, 22 is a diaphragm separating the upstream chamber 20 and the downstream chamber 21, 23 is the upstream chamber 20 and the downstream chamber 21 , A valve for controlling the opening / closing of the discharge port 20a in conjunction with the diaphragm 22, and 25 for the diaphragm 22.
A spring for elastically pressing the valve 24 in the closing direction of the valve 24,
The fuel pressure P ₅ of the upstream chamber 20 is controlled so as to balance with the sum of the adjusted fuel pressure P ₄ of the downstream chamber 21 and the load of the diaphragm 25. Therefore, the differential pressure (P ₅ −P ₄ ) between the upstream chamber 20 and the downstream chamber 21 is controlled to be constant, and the pressure loss of the differential pressure jet 23 is also constant. Second fuel pressure chamber
The fuel flow rate Q ₃ returned to 14 is also controlled to be constant. Further, the fuel flow rate Q ₁ that passes through the metering jet 19 and flows into the upstream chamber 20 is the sum of the injection flow rate Q ₂ and the constant return flow rate Q ₃ .

The present embodiment is configured as described above, and the operation will be described next.

When the engine is operating, the intake manifold pressure is applied to the second fuel pressure regulator 2 to be converted into the fuel pressure P ₁ (see FIG. 2), which is sent to the second fuel pressure regulator 6 through the fuel passage 7. By electronic control unit 11 with first and second solenoid valves
The duty ratios of 9 and 10 are 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, 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 ₃ generated between both solenoid valves is large when the engine speed is low, and is low when the engine speed is high.

By the way, the fuel flow rate required for 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 by the pressure, and the pressure difference (P ₁
Since it is possible to replace the -P _2), applied rate of P ₁ according to the engine rotational speed (first and second solenoid valve 9,
By adjusting the duty ratio of 10) and converting the obtained fuel pressure P ₃ into the adjusted fuel pressure P ₄ in the third fuel pressure regulator 12, as shown in FIG. 5, the adjusted fuel pressure P ₄ according to the required fuel flow rate is obtained. Can be generated. The adjusted fuel pressure P ₄ increases / decreases in accordance with the increase / decrease in intake manifold pressure, and its rate of change (slope) decreases / increases in accordance with the increase / decrease in engine speed.

Then, the adjusted fuel pressure P ₄ is supplied from the second fuel pressure chamber 14 to the fuel injection valve 18
The flow rate of the differential pressure jet 23 is controlled to be constant (= Q ₃ ) regardless of the change in the fuel pressure P ₄ of the downstream chamber 21. Therefore, it is adjusted as shown in FIG. The fuel pressure P ₅ of the upstream chamber 21 changes according to the increase or decrease of the fuel pressure P ₄ . Meanwhile, the weighing jet 19
Since determined by fuel flow rate Q ₁ is the differential pressure to pass through the (P ₁ -P _5), the adjusting fuel pressure P ₄ is [Delta] P ₄ decreases, also [Delta] P ₅ to decrease the fuel pressure P ₅ of the upstream chamber 20, the pressure difference (P ₁ -P ₅₎ is increased. Then, as shown in FIG. 7, the flow rate Q ₁ flowing into the upstream chamber 20 via the metering jet 19 increases, but the flow rate of the differential pressure jet 23 is constant at Q ₃ , so the fuel pressure of the upstream chamber 20 is increased. P ₅
And the diaphragm 22 is displaced toward the downstream chamber 21 side to increase the valve opening amount of the valve 24, and the fuel injection amount Q from the discharge port 20a is increased.
₂ (= Q ₁ −Q ₃ ) increases. Then, the fuel pressure P ₅ of the upstream chamber 20 returns to a predetermined value equal to the sum of the adjusted fuel pressure P ₄ and the load of the spring 25, and balances.

This fuel injection amount Q ₂ corresponds to the adjusted fuel pressure P ₄ , and therefore matches the above-mentioned required fuel flow rate.

Further, when the adjusted fuel pressure P ₄ increases by ΔP ₄ , the fuel pressure P ₅ of the upstream chamber 20 also increases by ΔP ₅ based on FIG. 6, and the metering jet 19
Since the differential pressure (P ₁ −P ₅ ) before and after decreases and the fuel flow rate Q ₁ decreases, the fuel injection amount Q ₂ corresponding to the required fuel flow rate also decreases.

When the intake manifold pressure is minimum, P ₁ =
It becomes P ₂ , and the adjusted fuel pressure P ₄ = P regardless of the engine speed
₄₀ (see FIG. ₅ ), and the fuel flow rate Q ₁ = Q ₃ and Q ₂ = 0 due to the differential pressure (P ₁ −P ₅ ) at this time (see FIG. 7).

By the way, the fuel flow rate Q ₁ of the metering jet 19 changes in proportion to the square root of the differential pressure across the front and rear (P ₁ −P ₅ ), as shown in FIG. 7, but returns to the flow rate Q ₁ in addition to the injection flow rate Q _2. by previously providing a constant flow rate Q ₃ being, can be injection flow rate Q ₂ is taken out portions which varies linearly with the pressure difference (P ₁ -P _5). Therefore, with respect to the flow rate Q ₁ of the measuring jet 19 and the differential pressure (P ₁ -P ₅ ) across the metering jet 19, it is possible to obtain a wide dynamic range sufficient for an automobile.

As described above, according to this embodiment, since the structure is relatively simple, the manufacturing cost can be reduced, the responsiveness is good, and the fuel injection device having a sufficient dynamic range for an automobile is realized. can do.

Although the first and second solenoid valves 9 and 10 respectively constitute opening area setting means, the opening area setting means is not limited to the solenoid valve, and the opening area can be electrically changed by using a stepping motor or the like. You may make it increase / decrease. Alternatively, either one of the two opening area setting means may be configured as a jet.

Further, although the above-mentioned embodiment relates to a single-point fuel injection device, it goes without saying that it can be applied to a multi-point fuel injection device. In this case, the fuel injection valve 18 and the metering jet
19 may be provided for each cylinder and connected to the single first fuel pressure regulator 2 and the third fuel pressure regulator 12, respectively, so that the fuel injection amount Q ₂ can be evenly distributed to each cylinder.

〔The invention's effect〕

As described above, the fuel injection device according to the present invention includes the first fuel pressure regulator and the opening area setting means for generating the adjusted fuel pressure according to the required fuel flow rate of the engine, and the metering jet according to the adjusted fuel pressure to the upstream chamber. A fuel injection valve that divides the remaining fuel flow rate other than the constant flow rate returned through the differential pressure jet from the inflowing fuel flow rate, so that the structure is relatively simple and the manufacturing cost is low. In addition, it has a practically important advantage in that it has excellent responsiveness and has a sufficient dynamic range for automobiles.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a fuel injection device according to the present invention, FIG. 2 is a view showing a relationship between intake manifold pressure and fuel pressure P ₁ in a first fuel pressure regulator, and FIG. 3 is a pulse signal. Fig. 4 is a diagram showing the cycle of the pulse signal according to the engine speed, and Fig. 5 is an adjusted fuel pressure P ₄ according to the intake manifold pressure and the engine speed.
FIG. 6 is a diagram showing the relationship between the adjusted fuel pressure P ₄ and the fuel pressure P _{5 in the} upstream chamber, and FIG. 7 is a diagram showing the relationship between the differential pressure (P ₁ −P ₅ ) and each fuel flow rate. is there. 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, 24 ... Valve.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F02M 69/52 F02D 3/00 C

Claims (1)

[Claims] 1. A first fuel pressure regulator for generating a fuel pressure according to an intake manifold pressure, a second fuel pressure regulator for generating a constant fuel pressure, and a fuel passage connecting the first and second fuel pressure regulators. Between the intake manifold pressure and the engine speed, at least one of which generates a fuel pressure according to the engine speed, and two opening area setting means capable of adjusting the opening area according to the engine speed; and the intake manifold pressure and the engine speed. Fuel pressure from the first fuel pressure regulator via a metering jet and an upstream chamber having a fuel discharge port, and the adjusted fuel pressure is applied and the differential pressure difference is applied. A downstream chamber that communicates with the upstream chamber via a jet and returns a constant flow rate,
A fuel injection valve having a diaphragm for partitioning the upstream chamber and the downstream chamber and interlocking with a valve capable of opening and closing a discharge port.