JPH0618047Y2 - Fuel injection engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a fuel injection engine.

[Prior art]

In a vehicular engine, a fuel injector is used as a fuel supply means instead of a conventional carburetor from the viewpoint of improving fuel control accuracy. In this fuel injection engine, there is one in which a fuel injection valve is provided in a cylinder and an intake passage of the engine, and either or both of the injection valves are driven according to the operating state of the engine. Conventionally, there is one disclosed in JP-A-54-69607. That is, when the engine is under a low load, the fuel injection valve provided in the cylinder injects an amount of fuel according to the load, and collects the air-fuel mixture in the vicinity of the spark plug to improve the ignitability, thus making the fuel unstable. When the engine has a high load, the fuel injection valve provided in each of the cylinder and the intake passage injects a quantity of fuel corresponding to the load to uniformly distribute the fuel into the combustion chamber. It is designed to generate an air-fuel mixture and thus improve output under high load.

Here, considering the influence of the fuel pressure on the performance of the fuel injection valve, the fuel injection amount is generally determined by the differential pressure between the fuel pressure and the injection space internal pressure, and the valve opening period of the injection valve. For the injection valve in the intake passage, the valve opening period is made relatively long to promote the mixing of the fuel and the air flowing in the intake passage, and the pressure in the intake passage, which is the injection space, is not so high. Considering the case where the amount is small, it is desirable that the fuel pressure of the injection valve in the intake passage is low.

On the other hand, regarding the in-cylinder injection valve, the injection valve is used for the purpose of stratifying the air-fuel mixture as described above, the valve opening period is relatively short, and the pressure fluctuation in the combustion chamber that is the injection space is Since it is large, it is desirable that the fuel pressure of the cylinder injection valve is high. Also, the opening period of this in-cylinder injection valve is short,
Since the vaporization and atomization time of the fuel is short, it is desirable to increase the fuel pressure in order to promote atomization of the fuel.

However, in the conventional fuel injection type engine of this type, such a point is not taken into consideration at all, and the same fuel pressure is applied to both the in-cylinder injection valve and the intake passage injection valve. In this case, the fuel control accuracy and fuel atomization cannot be sufficiently secured for the in-cylinder injection valve, and when the fuel pressure is high, the valve opening period of the intake passage injection valve should be extremely shortened, for example, at low rotation and low load. There is a problem that it is difficult to control the injection valve.

[Purpose of device]

In view of such a problem, the present invention intends to provide a fuel injection type engine that can secure fuel control accuracy and atomization for the in-cylinder injection valve and can easily control the intake passage injection valve. .

[Constitution of device]

In view of this, the present invention proposes a fuel injection engine in which a fuel injection valve is provided in a cylinder and an intake passage to inject fuel from one or both of the injection valves according to the operating state of the engine. The fuel pressure control means for setting the fuel pressure higher than the fuel pressure of the injection valve in the intake passage is provided, and further, the bypass passage for bypassing the in-cylinder injection valve and the fuel pressure control means is provided in the fuel supply passage.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

1 to 4 show a fuel injection engine according to an embodiment of the present invention. In the figure, reference numeral 1 denotes an engine, a throttle valve 3 is arranged in the intake passage 2 of the engine 1, an air flow meter 4 is provided upstream of the throttle valve 3 of the intake passage 2, and an upstream of the intake passage 2 is provided. The end reaches the air cleaner 5. A first fuel injection valve (hereinafter also referred to as a direct injection valve) 7 is provided in a cylinder of the engine 1 so as to face the combustion chamber 6, and an intake passage 2 of the engine 1 is provided with a second fuel injection valve downstream of the throttle valve 3. A fuel injection valve (hereinafter also referred to as an intake pipe injection valve) 8 is provided.

On the other hand, one end of a fuel supply passage 10 is connected to the fuel tank 9, and first and second fuel injection valves 7 and 8 are provided in the fuel supply passage 10 in the first and second order with respect to the fuel tank 9. A fuel pump 11 and a fuel filter 12 are provided between the fuel tank 9 of the fuel supply passage 10 and the first fuel injection valve 7. Further, one end of a fuel return passage 13 is connected to the other end of the fuel supply passage 10, and a fuel pressure regulator 14 for controlling the fuel pressure according to the intake negative pressure is connected to the connection portion of both and the downstream side of the first fuel injection valve 7. , 24 are interposed, and the other end of the fuel return passage 13 reaches the fuel tank 9. Here, the fuel pressure regulator 24 on the downstream side of the first fuel injection valve 7 sets the fuel pressure higher than that of the other fuel pressure regulator 14.

In the middle of the fuel supply passage 10, the first fuel injection valve 7
And the fuel pressure regulator 24 are bypassed to form a bypass passage 15, and a bypass valve 16 is provided in the middle of the bypass passage 15 and the bypass valve 16 is provided.
A chamber 17 is formed to mitigate fluctuations in fuel pressure in the fuel supply passage caused by opening and closing.

Further, in the figure, 18 is a crank angle sensor for detecting the rotation angle of the engine, 19 is a throttle opening sensor for detecting the opening of the throttle valve 3, 20 is an O ₂ sensor provided in an exhaust passage 21 of the engine, and 22 is A water temperature sensor for detecting an engine cooling water temperature, 23 is a control unit, and the control unit 23 drives one or both of the first and second fuel injection valves 7 and 8 in accordance with the operating state of the engine. Further, when only the second fuel injection valve 8 is driven, an open signal is output to the fuel pressure regulator bypass valve 16 to open it.

And in the above structure, the first fuel injection valve 7
The fuel pressure regulator 24 on the downstream side serves as fuel pressure control means for setting the fuel pressure of the first fuel injection valve 7 higher than the fuel pressure of the second fuel injection valve 8, and the control unit 23 responds to the operating state of the engine. It is an injection valve drive means for driving either or both of the first and second fuel injection valves 7, 8.

Next, the operation will be described with reference to FIGS. Here, FIG. 2 is a flow chart of the processing of the control unit 23, and FIG. 3 is a flow chart showing an intake pipe injection region, a direct injection region, a combined injection region and a fuel cut region with the engine speed and the throttle opening as parameters. FIG. 4 shows a function fn for determining the switching increase rate or the switching decrease rate CCHn with respect to the elapsed time Δtn (n is 1 to 4) from the start or stop of intake pipe injection or direct injection.

When the engine operates, the control unit 23 executes the process shown by the flowchart in FIG. 2, and first reads the outputs of the various sensors 4, 18 to 20, 22 which are in the operating state (stepper 30) to determine the engine speed and throttle opening. It is determined whether or not the operating region of the engine, which is determined by the degree, is equal to or greater than the fuel cut region boundary line a (see FIG. 3) (step 3
1) If the fuel cut region boundary line is less than or equal to "a", the process returns to step 30 described above. Thus, when the operating region of the engine is the fuel cut region, the injection valves 7 and 8 are not driven and the fuel supply is cut. It will be.

On the other hand, when the operating region of the engine is above the fuel cut region boundary line a, the control unit 23 calculates the total basic pulse width τ0 according to the engine speed and the intake air amount (step 32), and performs direct injection. It is determined whether or not the region is a power region, that is, whether or not it is below the intake pipe injection region boundary line b (step 3
3) In the case of the intake pipe injection region boundary line b or less, the elapsed time Δ considering the fuel shortage until the direct fuel pressure is secured by the switching increase rate CCH1 depending on whether or not the direct injection is started. A value f1 (Δt1) determined by t1 and a predetermined function f1 (see FIG. 4) is set or zero (steps 34, 35, 36), and whether or not the region is the region where the intake pipe injection should be performed next, that is, It is determined whether or not the direct injection region boundary line c (see FIG. 4) or more (step 37), and if it is the direct injection region boundary line c or more, the switching amount increase depending on whether or not immediately after the start of the intake pipe injection. The value f2 of the rate CCH2 determined by the elapsed time Δt2 and a predetermined function f2 (see FIG. 4) in consideration of the shortage of fuel adhering to the intake pipe wall surface.
(Δt2) or set to zero (steps 38, 39, 4
0), the total basic pulse width τ0, the distribution coefficient k1, the switching increase rates CCH1, CCH2, the capacity correction coefficient k2 of the injection valve 7 and the invalid injection periods τBATM, τB of the injection valves 7 and 8 described above.
Intake pipe injection pulse width TM [= k1 × τ0 using ATD
× (1 + CCH2) + τBATM], and direct injection pulse width TD [= (1-k1) × k2 × τ0 × (1+
CCH1) + τBATD] (steps 41, 4
2) Add fuel injection pulses having the pulse widths TM and TD to the intake pipe injection valve 8 and the direct injection valve 7 to inject fuel into both the injection valves 8 and 7 (steps 43 and 44), thus operating the engine. Area is combined injection area (see Fig. 3)
In this case, both the first and second injection valves 7 and 8 are driven to inject and supply the fuel in the combustion chamber 6 and the intake passage 2 in an amount corresponding to the operating state of the engine.

Further, in the case of the direct injection region boundary line c or less, the control unit 23 determines the switching time reduction rate CCH3 in consideration of the inflow of fuel into the intake pipe wall surface depending on whether or not immediately after the intake pipe injection is stopped, and the elapsed time Δt3. And the value f3 (Δt3) determined by the predetermined function f3 (see FIG. 4) or zero (steps 45, 46, 47), the intake pipe injection pulse width TM is set to zero, and Direct injection pulse width TD [= k2 × τ0 × (1 + CCH1-CCH3) +
τ BATD] is calculated (steps 48 and 49) and the above-described steps 43 and 44 are performed. Thus, when the operating region of the engine is the direct injection region (see FIG. 3), the first fuel injection valve 7 Only the fuel is driven and the amount of fuel corresponding to the operating state of the engine is injected and supplied into the combustion chamber 6.

Further, when the operating region of the engine is equal to or higher than the intake pipe injection region boundary line b, the control unit 23 considers the shortage of the fuel adhering to the intake pipe wall surface as the switching increase rate CCH4 according to whether or not immediately after the start of the intake pipe injection. Then, after setting the value f4 (Δt4) according to the elapsed time Δt4 and the predetermined function f4 (see FIG. 4) or zero (steps 50, 51, 52), the direct injection pulse width TD is set. In addition to zero, the intake pipe injection pulse width TM [= τ0 × (1 + CCH4) + τBAT
M] is calculated (steps 53 and 54), an open signal is further output to the fuel pressure regulator bypass valve 16 to open it (step 55), and the above-mentioned steps 43 and 44 are performed. In the case of the intake pipe injection region (see FIG. 3), only the second fuel injection valve 8 is driven to inject and supply an amount of fuel corresponding to the operating state of the engine into the intake passage 2, and at that time, the fuel pressure is increased. The regulator bypass valve 16 will be opened.

In the device of the present embodiment as described above, the fuel pressure regulator is provided for each of the first fuel injection valve provided in the cylinder and the second fuel injection valve provided in the intake passage, and the fuel pressure of the first fuel injection valve is adjusted to the first value. Since the fuel injection pressure is set higher than that of the second fuel injection valve, the fuel pressure of the first fuel injection valve can be increased to ensure fuel control accuracy and atomization, and the fuel pressure of the second fuel injection valve can be ensured. Can be appropriately set to prevent the injection valve from becoming difficult to control, such as the valve opening period becoming extremely short.

Further, in the above device, when only the second fuel injection valve is driven, the first fuel injection valve and its fuel pressure regulator are bypassed so that the fuel flows, so that the load acting on the fuel pump can be reduced.

[Effect of device]

As described above, according to the present invention, in the fuel injection engine in which the fuel injection valve is provided in the cylinder and the intake passage, and the fuel is injected from one or both of the injection valves according to the operating state of the engine, Since the fuel pressure control means for setting the fuel pressure of the internal injection valve higher than that of the intake passage internal injection valve is provided, it is possible to ensure fuel control accuracy and atomization for the injection valve of the cylinder, and to inject fuel for the injection valve of the intake passage. This has the effect of preventing difficulty in control.

Further, a bypass passage that bypasses the in-cylinder injection valve and the fuel pressure control means is provided in the fuel supply passage, and when only the intake passage injection valve is driven, the bypass passage is opened to bypass the fuel going to the in-cylinder injection valve. I did so,
There is an effect that the driving load of the fuel supply system can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a fuel injection engine according to an embodiment of the present invention, FIG. 2 is a diagram showing a flow chart of arithmetic processing of a control unit in the engine, and FIG. 3 is an engine. FIG. 4 is a diagram showing an intake pipe injection region, a direct injection region, a combined injection region, and a fuel cut region in which the rotational speed and the throttle valve opening are parameters, and FIG. 4 shows the progress from the start or stop of the intake pipe injection or the direct injection. It is a figure which shows the function fn for determining the switching increase rate or switching decrease rate CCHn with respect to time (DELTA) tn. 1 ... Engine, 2 ... Intake passage, 7 ... First fuel injection valve, 8 ... Second fuel injection valve, 15 ... Bypass passage, 16 ... Bypass valve, 23 ... Control unit (injection Drive means), 24 ... Fuel pressure regulator (fuel pressure control means).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiji Tajima 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. 28243 (JP, U) Actual Kohei 4-22061 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. A first fuel injection valve provided in a cylinder of an engine, a second fuel injection valve provided in an intake passage of the engine, and the first and second fuel injection valves according to an operating state of the engine. An injection valve drive means for driving either one or both of the fuel injection valves; and a fuel pressure control means for setting the fuel pressure of the first fuel injection valve higher than the fuel pressure of the second fuel injection valve. The first fuel injection valve, the fuel pressure control means, and the second fuel injection valve are sequentially arranged from the upstream of the passage, and the first fuel injection valve and the fuel pressure control means are bypassed to the fuel supply passage, and the bypass valve A fuel injection engine, characterized in that a bypass passage having an opening is provided, and the bypass valve is opened when the second fuel injection valve operates independently.