JPH0771285A - Fuel supply control device for two-cycle engine - Google Patents

Abstract

PURPOSE:To prevent blow-back of fuel certainly and improve accelerating performance for a two-cycle engine. CONSTITUTION:In the fuel supply control device of a two cycle engine which is provided with a lead valve 11 in an intake passage 10, and being provided in order to supplying fuel through the lead valve 11, an injector 12 for injecting fuel is provided in the intake passage 10 provided upstream from the lead valve 11. A fuel injection control means (ECU) 30 is provided to control the injector 12 so as to expedite a fuel injection timing more as engine rotational speed becomes higher or an engine load becomes larger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-cycle engine, and more particularly, to an improvement in a fuel supply control device capable of reliably preventing blowback of fuel in an intake passage and improving acceleration.

[0002]

2. Description of the Related Art For example, a two-cycle engine for an outboard motor has been proposed which is provided with a reed valve in the intake passage to prevent the blowback of fuel. It is also proposed to provide an injector for injecting fuel therein. 2 like this
In a cycle engine, the piston speed is high when the engine is rotating at high speed, and the intake air amount is large when the engine is operating under high load, and in either case, the negative pressure and positive pressure in the crank chamber change quickly. The open / close speed of the reed valve is fast.

[0003]

However, in the conventional two-cycle engine, the fuel injection timing of the injector does not correspond to the opening / closing timing of the reed valve, so that the fuel is blown back in the intake passage. There are cases. As a result, sufficient fuel is not supplied into the crank chamber at the time of acceleration, which causes a problem that acceleration performance is deteriorated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel supply control device for a two-cycle engine which can surely prevent the blowback of fuel and improve the acceleration performance. I am trying.

[0005]

2 according to the invention of claim 1
A fuel supply control device for a cycle engine includes a reed valve in an intake passage, and in a fuel supply control device for a two-cycle engine that supplies fuel through the reed valve, a fuel supply control device is provided in an intake passage upstream of the reed valve. An injector for fuel injection is provided, and fuel injection control means for controlling the injector is provided so that the fuel injection timing is advanced as the engine speed increases or the engine load increases.

According to a second aspect of the present invention, there is provided a fuel supply control device for a two-cycle engine according to the first aspect, wherein the fuel injection control means is arranged so that the fuel injected from the injector is opened when the reed valve is opened. The fuel injection timing of the injector is controlled so as to reach the reed valve. Here, the fuel injection timing includes at least one of fuel injection start timing and fuel end timing.

According to a third aspect of the present invention, there is provided a fuel supply control device for a two-cycle engine according to the first aspect, wherein the fuel injection control means starts the fuel injection by the injector after the reed valve is opened. It is characterized in that the fuel injection start timing of the injector is controlled.

[0008]

According to the first aspect of the invention, the fuel injection timing of the injector is advanced by the control of the injector by the fuel injection control means as the engine speed increases or the engine load increases. As a result, the fuel injection timing becomes faster according to the switching speed between the positive pressure and the negative pressure in the crank chamber, that is, the opening / closing speed of the reed valve. As a result, it is possible to reliably prevent the fuel from being blown back, and by this, it is possible to supply sufficient fuel into the crank chamber during acceleration and improve the acceleration performance.

According to the second aspect of the present invention, the fuel injected from the injector reaches the reed valve when the reed valve is opened by controlling the fuel injection timing by the fuel injection control means. This makes it possible to reliably supply the fuel injected from the injector into the crank chamber via the reed valve, and reliably prevent the fuel from being blown back. Further, this can improve the acceleration performance.

According to the third aspect of the present invention, the fuel injection control means controls the fuel injection start timing to start the fuel injection by the injector after the reed valve is opened. This makes it possible to more reliably supply the fuel injected from the injector into the crank chamber via the reed valve, and more reliably prevent the fuel from being blown back. Further, this can improve the acceleration performance.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 5 are views for explaining a fuel supply control device for a two-cycle engine for an outboard motor according to an embodiment of the present invention. FIG. 1 is an outboard motor adopting the fuel supply control device. 2 is an enlarged partial view of FIG. 1, FIG. 3 is a diagram showing fuel injection start timing and fuel injection end timing of the injector, and FIG. 4 is fuel injection start timing of the injector for intake amount and throttle valve. FIG. 5 is a diagram showing the relationship with the opening degree, and FIG. 5 is a control flowchart of the fuel supply control device. In addition,
In FIG. 1, F indicates the bow side, R indicates the stern side, and the lower left part of the figure shows an AA cross section of the upper left part.

In these figures, reference numeral 1 is an outboard motor of a vertically mounted V-type 6-cylinder two-cycle engine, in which a piston 3 is slid in a cylinder bore formed to form a V bank of a cylinder block 2. The piston 3 is movably inserted and arranged, and the piston 3 is connected to the crankshaft 5 by a connecting rod 4. A cylinder head 6 is mounted on the mating surface of the cylinder block 2, and a spark plug 7 is inserted in a combustion recess formed in the cylinder head 6. A crank chamber 8 is provided on the side opposite to the head of the cylinder block 2. A pressure sensor 31 for measuring the in-cylinder pressure is attached to the cylinder head 6. Further, the crankshaft 5 is provided with a sensor 33 for detecting the crank angle (engine speed), and the crank chamber 8 is provided with a pressure sensor 34 for measuring the pressure in the crank chamber.

An intake passage 10 is connected to the crank chamber 8. A reed valve 11 for preventing backflow of intake air is arranged near the opening of the intake passage 10 on the crank chamber side. An injector 12 for injecting fuel into the intake passage is installed in the intake passage 10, and a high-pressure fuel supply device 13 is connected to the injector 12. A temperature sensor 32 for measuring intake air temperature or engine temperature is provided at the crank chamber side opening of the intake passage 10. Further, the exhaust passage 26
FIG. 1 shows an O ₂ sensor 35 for detecting the O ₂ concentration in the exhaust gas and a pressure sensor 3 for detecting the back pressure.
And 6 are provided. Further, a temperature sensor 37 for detecting the engine temperature is provided.

A throttle valve 15 is disposed in the intake passage 10, and the idle position of the throttle valve 15 is set at a position inclined by α degrees from the fully closed position, as shown in FIG. . This angle α is larger than the usual setting angle of 2-3 °, and is preferably 15 °.
It is set in the vicinity of 20 to 20 degrees. Thus, by setting the idle position of the throttle valve 15 to a substantially intermediate opening position between the fully closed position and the fully open position, the flow of intake air having a flow rate and a flow velocity required for acceleration is already secured during idle operation. Will be there. It is also possible to use a throttle valve having a hole or a groove as the valve 15 so that the valve is substantially closed and substantially corresponds to the substantially intermediate opening position.

Although not shown, a sensor for detecting the amount of rotation of the throttle valve 15, that is, the throttle valve angle is provided. Further, the throttle valve 15 is provided with a pickup bar 16 extending in a direction substantially perpendicular to the valve surface. The pickup bar 16
A spherical contact portion 17 is provided at the tip of the.

On the other hand, a cam mechanism 20 is provided on the side of the throttle valve 15. The cam mechanism 20 has a cam member 22, and one end of the cam member 22 is
A support shaft 21 rotatably supported is fixed. One end of an accelerator bar 24 is attached to the cam member 22 via a pin 23, and the other end of the accelerator bar 24 is connected to the accelerator. Further, when the accelerator pedal is not depressed, the cam member 22 is located at the idle position shown by the solid line, and the pickup bar 1
A predetermined gap s is formed between the contact portion 17 at the tip of the six. Further, the support shaft portion 21 is provided with a cam sensor (not shown) for detecting the rotation amount of the cam member 22.

With this structure, the cam member 22 rotates in conjunction with the accelerator operation, and comes into contact with the contact portion 17 at the pickup position (see the chain line in FIG. 2) and the throttle bar 15 via the pickup bar 16. To the fully open position (see the position indicated by the chain double-dashed line in the figure). The ignition timing is controlled according to the amount of rotation of the cam member 22 until the cam member 22 reaches the pickup position. That is, at the time of idling, the ignition timing is controlled to the retard side, whereby the combustion of the engine is suppressed despite the increase of the intake flow rate and the flow velocity, and at the time of acceleration, the ignition timing is advanced to the advanced side according to the rotation amount of the cam mechanism. On the other hand, the flow of intake air required for acceleration is already ensured, so that combustion of the engine is promoted and the engine can be rotated at a high speed in a short period of time to improve the acceleration performance.

The engine 1 is an ECU 3 as a control unit.
It has 0. A map for determining the fuel injection timing and the injection width according to the engine speed and the throttle valve opening is stored in the ECU 30.
This map will be described with reference to FIGS. 3 and 4. In FIG. 3, the vertical axis represents the crank angle and the horizontal axis represents the engine speed (or engine load). In the figure, the solid line A indicates the timing when the reed valve 11 opens, and the solid line B indicates the reed valve 11. It shows the closing timing. That is, the shaded area surrounded by the solid lines A and B indicates the opening period in which the reed valve 11 is open.

The fuel injection start timing of the injector 12 determined by the above map is shown by a broken line T1 in FIG.
Further, the fuel injection end timing is shown by a broken line T2, and therefore, the portion surrounded by these broken lines T1, T2 shows the fuel injection time width. It can be seen from FIG. 3 that the fuel injection timing (fuel injection start timing and fuel injection end timing) with respect to the opening / closing timing of the reed valve 11 becomes faster as the engine speed increases (or the engine load increases). Regarding how to accelerate the fuel injection start timing T1 with respect to the reed valve opening timing A, the timing is set so that the fuel immediately after the start of injection reaches the reed valve 11 when the reed valve 11 is open. Done. Regarding how to accelerate the fuel injection end timing T2 with respect to the reed valve closing timing B, the timing is set so that the fuel immediately before the end of injection reaches the reed valve 11 when the reed valve 11 is open. Done. Note that FIG.
As shown in, the fuel injection start timing T1 shifts to the T1 ′ side (that is, the crank angle retarding side) as the intake amount is smaller and the throttle valve opening is smaller. By setting the fuel injection timing and the injection width in this way, it is possible to reliably prevent the fuel from being blown back in the intake passage 10, and it is possible to supply sufficient fuel into the crank chamber during acceleration, thereby improving the acceleration performance. .

Further, the ECU 30 includes in-cylinder pressure detection sensor 31, throttle opening (intake air amount) detection sensor, cam angle detection sensor, intake air temperature (engine temperature) detection sensor 3.
2, the input signals of the crank angle detection sensor 33, the crank chamber pressure detection sensor 34, the O ₂ sensor 35, the back pressure detection sensor 36, the engine temperature detection sensor 37, the atmospheric pressure detection sensor, and the cooling water detection sensor are input. There is. The output signal of the ECU 30 is input to each of the spark plug 7 and the injector 12.

Next, the control operation by the ECU 30 will be described with reference to the flowchart of FIG. When the program starts, first in step S1 of FIG.
Detects throttle valve opening and engine speed.
Next, in step S2, the fuel injection timing and injection width are read from the map based on the throttle valve opening and engine speed detected in step S1 (see FIG. 3). Then, the throttle valve 3 controls the injector 12 based on the fuel injection timing and the fuel injection width read in step S2 to inject fuel.

As described above, in this embodiment, the fuel injection timing of the injector 12 is advanced as the engine speed increases (or the engine load increases). As a result, the fuel injection timing becomes faster according to the switching speed between the positive pressure and the negative pressure in the crank chamber, that is, the opening / closing speed of the reed valve 11. As a result, it is possible to reliably prevent the fuel from being blown back, and by this, sufficient fuel can be supplied into the crank chamber 8 at the time of acceleration, and the acceleration performance can be improved. Moreover, the fuel injected from the injector 12 is
When the reed valve 11 is open, the reed valve 1
Reach 1. As a result, the fuel injected from the injector 12 can be reliably supplied into the crank chamber 8 via the reed valve 11, and the blowback of the fuel can be reliably prevented. Further, this can improve the acceleration performance.

In the above embodiment, the timings of both the fuel injection start timing T1 and the fuel injection end timing T2 are accelerated, but in the present invention, either one of T1 and T2 is accelerated. Can also be applied.

In the above embodiment, the example in which the reed valve 11 is opened after the fuel injection is started has been described. However, conversely, the fuel injection may be started after the reed valve 11 is opened. As a result, the fuel injected from the injector 12 is supplied to the crank chamber 8 via the reed valve 11.
It is possible to more reliably supply the fuel to the inside, and it is possible to more reliably prevent the blowback of the fuel. Further, this can improve the acceleration performance.

[0025]

As described above, in the fuel supply control device for a two-cycle engine according to the invention of claim 1, the fuel injection timing is advanced as the engine speed increases or the engine load increases. There is an effect that the blowback of the fuel can be surely prevented and that the acceleration performance can be improved.

In the fuel supply control device for the two-cycle engine according to the second aspect of the present invention, the fuel injected from the injector reaches the reed valve when the reed valve is open, so the fuel is injected from the injector. It is possible to reliably supply the fuel, and it is possible to surely prevent the fuel from being blown back, and it is possible to improve the acceleration performance.

In the fuel supply control device for the two-cycle engine according to the third aspect of the present invention, the fuel injection by the injector is started after the reed valve is opened, so that the fuel injected from the injector is more reliably supplied. Therefore, it is possible to more reliably prevent the fuel from being blown back and to improve the acceleration performance.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an outboard motor two-cycle engine that employs a fuel supply control device according to an embodiment of the present invention.

FIG. 2 is an enlarged partial view of FIG.

FIG. 3 is a diagram showing a fuel injection start timing and a fuel injection end timing of an injector controlled by the fuel supply control device in a correlation between an engine speed and a crank angle.

FIG. 4 is a diagram showing a fuel injection start timing of the injector as a relationship between an intake amount and a throttle valve opening.

FIG. 5 is a control flowchart of the fuel supply control device.

[Description of Reference Signs] 1 engine 10 intake passage 11 reed valve 12 injector 30 ECU (fuel injection control means)

Claims (3)

[Claims] 1. A fuel supply control device for a two-cycle engine, comprising a reed valve in an intake passage and supplying fuel via the reed valve, wherein a fuel injection device is provided in an intake passage upstream of the reed valve. A fuel supply control device for a two-cycle engine, comprising an injector, and fuel injection control means for controlling the injector so that the fuel injection timing is advanced as the engine speed increases or the engine load increases. 2. The fuel injection control means according to claim 1, wherein the fuel injection timing of the injector is adjusted so that the fuel injected from the injector reaches the reed valve within a period in which the reed valve is open. A fuel supply control device for a two-cycle engine, which is controlled. 3. The fuel injection control means according to claim 1, wherein the fuel injection control means controls the fuel injection start timing of the injector so that the fuel injection by the injector is started after the reed valve is opened. Fuel supply control device for 2-cycle engine.