JPH0571405A - In-cylinder fuel injection type two-cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To provide sufficient stratified combustion at a low speed and reduce inconsistent combustion which is liable to occur in such a case. CONSTITUTION:In an in-cylinder fuel injection type two-cycle internal combustion engine which has a cylinder head 14 provided with a fuel injection valve 50 and a spark plug 21, a piston 11 has the recessed portion 11a on the top combustion chamber side and the protruded portion 11b protruded to the recessed portion 11a on the combustion chamber side and the spark plug 21 has the electrode portion 21a faced into the recessed portion near the protruded portion, while the fuel injection of a fuel injection valve 50 is directed to the protruded portion 11b and so arranged that fuel directed to the protruded portion 11b can hit on the protruded portion 11b, be reflected and directed to the electrode portion 21a. On the other hand, the opening/closing timing of the fuel infection valve 50 and the sparking timing of the spark plug 21 at a low speed are set near the top dead center of the piston 11 and controlled so that at least a part of fuel directed to the electrode portion 21a can be passed therethrough during discharging of the electrode portion 21a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder fuel injection type two-cycle internal combustion engine which directly injects high-pressure fuel into a combustion chamber.

[0002]

2. Description of the Related Art A recess is formed on the top surface of a piston and a projection is provided on the inner wall surface of the recess to form a collision surface on the projection, so that most of the fuel is discharged from a fuel injection valve provided in a cylinder head. A direct injection layered structure in which an air-fuel mixture region that is denser than other regions is formed around the protrusion by injecting toward the collision surface and an ignition electrode located in this rich air-fuel mixture region is attached to the cylinder head during ignition. A combustion type four-cycle internal combustion engine is described in JP-A-63-162928.

[0003]

The internal combustion engine described in the above embodiment is a 4-cycle internal combustion engine. Therefore, the gas temperature after compression in the combustion chamber is higher and the temperature of the top surface of the piston is higher than that of the two-cycle internal combustion engine. Therefore, the fuel after injection is vaporized by the heat of the compressed gas that has been adiabatically compressed to have a high temperature and further by the heat of the hot piston top surface, and its kinetic energy is rapidly lost. As a result, the air-fuel mixture after collision on the top surface of the piston is almost vaporized, and it is difficult to reach the spark plug. Therefore, the spark plug must be placed sufficiently close to the top surface of the piston. Furthermore, since the kinetic energy of the air-fuel mixture after collision has disappeared, the air-fuel mixture that has reached the spark plug and ignited does not diffuse with the small kinetic energy, and it is difficult to expect complete combustion from this aspect.

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to sufficiently perform combustion at a low speed and to reduce irregular combustion that tends to occur at such a time.

[0005]

In order to achieve the above object, the present invention provides a cylinder fuel injection type two-cycle internal combustion engine equipped with a fuel injection valve and an ignition plug in a cylinder head, in which the top combustion chamber side of the piston is located. A concave portion and a convex portion projecting to the combustion chamber side are provided in the concave portion, and the electrode portion of the spark plug is made to face the concave portion near the convex portion, while the fuel injection direction of the fuel injection valve is changed. The fuel injection direction is arranged so that the fuel directed to the convex portion and directed toward the convex portion collides with the convex portion, and then is reflected and toward the electrode portion, while the fuel injection valve at low speed is While setting the opening and closing timing and the ignition timing of the spark plug near the top dead center of the piston,
The opening / closing timing of the fuel injection valve and the ignition timing of the spark plug are controlled so that at least a part of the fuel toward the electrode portion passes while the electrode portion is discharging. Is.

In order to achieve the above object, the present invention is a cylinder fuel injection type two-cycle internal combustion engine having a fuel injection valve and a spark plug in a cylinder head, and a concave portion on the top combustion chamber side of a piston and the concave portion. And a projection protruding toward the combustion chamber, the electrode portion of the spark plug is made to face the recess near the projection, while the fuel injection direction of the fuel injection valve is directed to the projection. The fuel injection direction is arranged so that the fuel directed to the convex portion collides with the convex portion and then reflects toward the electrode portion, while the fuel injection valve is opened / closed at low speed and the spark plug. While setting the ignition timing of the piston in the vicinity of the top dead center of the piston, the flight time from the time when the fuel is actually injected from the fuel injection valve to the time when the fuel is reflected by the convex portion and reaches the electrode portion, Instruction to close the fuel injection valve From the timing of adding the valve closing delay time from the valve closing instruction timing to the actual closing of the fuel injection valve to the valve closing instruction timing, the discharge start timing at which the spark plug starts discharging It is characterized by setting early.

In order to achieve the above object, the present invention provides a cylinder fuel injection type two-cycle internal combustion engine having a fuel injection valve and an ignition plug in a cylinder head, and a recess on the top combustion chamber side of a piston and the recess. And a projection protruding toward the combustion chamber, the electrode portion of the spark plug is made to face the recess near the projection, while the fuel injection direction of the fuel injection valve is directed to the projection. The fuel injection direction is arranged so that the fuel directed to the convex portion collides with the convex portion and then reflects toward the electrode portion, while the fuel injection valve is opened / closed at low speed and the spark plug. While setting the ignition timing of the piston in the vicinity of the top dead center of the piston, the flight time from the time when the fuel is actually injected from the fuel injection valve to the time when the fuel is reflected by the convex portion and reaches the electrode portion, Instruction to open the fuel injection valve From the timing of adding the valve opening delay time from the valve opening instruction timing to the actual opening of the fuel injection valve to the valve opening instruction timing, the discharge end timing at which the spark plug ends discharge It is characterized by being set late.

In order to achieve the above object, the present invention is a cylinder fuel injection type two-cycle internal combustion engine having a fuel injection valve and an ignition plug in a cylinder head, and a recess on the top combustion chamber side of a piston and the recess. And a projection protruding toward the combustion chamber, the electrode portion of the spark plug is made to face the recess near the projection, while the fuel injection direction of the fuel injection valve is directed to the projection. The fuel injection direction is arranged so that the fuel directed to the convex portion collides with the convex portion and then reflects toward the electrode portion, while the fuel injection valve is opened / closed at low speed and the spark plug. While setting the ignition timing of the piston in the vicinity of the top dead center of the piston, the flight time from the time when the fuel is actually injected from the fuel injection valve to the time when the fuel is reflected by the convex portion and reaches the electrode portion, Instruction to open the fuel injection valve From the timing of adding the valve opening delay time from the valve opening instruction timing to the actual opening of the fuel injection valve to the valve opening instruction timing, the discharge end timing at which the spark plug ends discharge It is characterized by being set late.

In order to achieve the above object, the present invention is directed to a cylinder fuel injection type two-cycle internal combustion engine having a cylinder head equipped with a fuel injection valve and an ignition plug so that the piston is opposed to the cylinder surface on which it slides. A scavenging hole and an exhaust hole respectively, and two planes that are parallel to the cylinder center axis and that connect both outer circumferential edges of the scavenging hole and both outer circumferential edges of the exhaust hole. The fuel injection valve and the ignition plug are arranged in the sandwiched space.

[0010]

In the low speed operation, the opening / closing timing of the fuel injection valve and the ignition timing of the spark plug are controlled so that at least a part of the fuel toward the electrode portion passes while the electrode portion is discharging. The fuel does not start passing through the electrode portion before the discharge starts, or the fuel does not start passing through the electrode portion after the discharge ends. Further, the fuel particles heading for the electrode portion are vaporized only in the outer peripheral portion because the ambient temperature is relatively low, and the central portion is still in a liquid state. By this, it spreads while igniting and promotes the combustion of the entire combustion chamber.

The scavenging air flowing from the scavenging hole to the exhaust hole remains in the combustion chamber even after the scavenging hole is closed.
According to the invention, the fuel particle group reflected by the convex portion is displaced toward the electrode portion side, enriching the supply of the air-fuel mixture around the electrode portion, and preventing misfire.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall schematic view of a fuel injection device in which the present invention is applied to an outboard motor. FIG. 2 is a vertical sectional view of a crankcase compression type two-cycle internal combustion engine to which the present invention is applied. 10
Is a crank chamber compression type two-cycle internal combustion engine, and the internal combustion engine 1
0 indicates the crankshaft 12 and the cylinder 1 as shown in FIG.
3, a cylinder head 14, a crankcase 15, and a piston 11. A combustion chamber 16 is formed by the piston 11, the cylinder 13 and the cylinder head 14. A crank chamber 17 is formed by the piston 11, the cylinder 13 and the crank case 15, and the crank shaft 12 is housed therein. An intake passage 18 having a throttle valve 19 in the crank chamber 17 via a reed-type check valve 20.
Are in communication. A scavenging passage 23 is formed in the cylinder 13. One end of this scavenging passage 23 is the crank chamber 17
The other end communicates with the combustion chamber 16 through the scavenging hole 24. As the piston 11 slides up and down in the cylinder 13, the scavenging passage 23 opens and closes with the combustion chamber 16.

The intake air is guided from the atmosphere to the intake passage 18 by the negative pressure in the crank chamber 17, is metered by the throttle valve 19, and then introduced into the crank chamber 17 through the check valve 19. Then, the intake air introduced into the crank chamber 17 is compressed by the piston 11 and is scavenged into the combustion chamber 16 through the scavenging passages 23, 23, 23.

As shown in FIG. 1, the fuel is sent from the fuel tank 5 through the fuel filter 6 by the low-pressure fuel pump 7 to the vapor separator 8 having the float chamber. The fuel fed into the vapor separator 8 is the second
The low-pressure fuel pump 9 supplies the high-pressure fuel pump 3 which is rotationally driven by the crankshaft 12. Therefore, the intake (not shown) of the high-pressure fuel pump 3 is always positive pressure.
The high-pressure fuel pump 3 discharges the fuel supplied from the low-pressure fuel pump 9 at a high pressure (70 to 100 kg / cm ² ), and the fuel injection valve 5 passes through the accumulator 10 and the fuel filter 11.
0 is supplying fuel. When the pressure of the high-pressure fuel supplied to the fuel injection valve 50 exceeds a certain level, the regulator 30 returns the fuel to the vapor separator 8.
As a result, the pressure of the fuel supplied to the fuel injection valve 50 is always kept constant (70 kg / cm ² in this embodiment). The fuel injection valve 50 includes a cylinder head 14 and a cylinder 1
3 is attached substantially parallel to the central axis of the combustion chamber 16 as described later.
Is injecting fuel into. The portion surrounded by the imaginary line A is the portion accommodated by the cowling (not shown) of the outboard motor. The vapor layer of the vapor separator 8 is communicated with the intake passage 18 so that the fuel vaporized component from the vapor separator 8 is burned in the combustion chamber 16 so that the HC component is not released to the atmosphere.

As shown in FIG. 3, the piston 11 has a cylindrical recess 11a whose center is recessed toward the side opposite to the combustion chamber.
Further, at the center of the concave portion 11a, a convex portion 11b protruding from the bottom surface thereof toward the combustion chamber is provided. Cylinder head 14
The fuel injection valve 50 attached to the cylinder 13 is disposed substantially parallel to the cylinder center axis of the cylinder 13, and the injection port 61 has a convex portion 11
It is arranged at the center position of b (61 in FIG. 4).
As shown in FIG. 4, the injection port 61 is located at a position (61 ′ in FIG. 4) displaced to the opposite side of the exhaust passage 22 described later.
), Or a position displaced toward the exhaust passage 22 (see FIG. 4).
61 ″) in any of the above. Further, the electrode portion 21a of the spark plug 21 is attached to the cylinder head 14 so as to face the concave portion 11a near the convex portion 11b. As shown in FIG. 4, the cylinder 13 has an exhaust passage 2
2, a scavenging passage 23a facing the exhaust passage 22, and a pair of left and right scavenging passages 23b and 23c with a line connecting the scavenging passage 23a and the exhaust passage 22 interposed therebetween, the ends of which are the sliding surface of the cylinder 13. To the exhaust hole 22a, the scavenging hole 24a, the scavenging hole 24b, and the scavenging hole 24c, respectively.
Is formed. These three scavenging passages 23a, 23
The so-called schnee scavenging is performed by scavenging the combustion chamber 16 with fresh air from b and 23c. Both the left and right outer edges of the scavenging hole 24a in the circumferential direction (portions of the lead lines of 24a in FIG. 4) and the left and right outer edges of the exhaust hole 22a in the circumferential direction (FIG. 4).
22a of the lead wire) and a plane connecting
The injection port 61 of the fuel injection valve 50 and the spark plug 2 are placed in a space sandwiched between two planes 25A and 25B parallel to the cylinder center axis.
1 discharge part 21a was arranged. Scavenging holes 24a, 24b,
After closing 24c, and also after closing the exhaust hole 22a,
A scavenging air flow from the scavenging hole 24a to the exhaust hole 22a remains in the combustion chamber 16. Therefore, the electrode portion 21a is located on the downstream side of the injection port 61, the fuel particle group colliding with the convex portion 11b is displaced to the electrode portion 21a side, and the supply of the air-fuel mixture around the electrode portion 21a becomes rich.

FIG. 5 is a sectional side view of the fuel injection valve 50. The fuel injection valve 50 will be described with reference to FIG. The fuel injection valve 50 is a sleeve 5 screwed to the cylinder head 14.
2, a valve body 54 fitted to the sleeve 52 via an O-ring 54a, a nozzle holder 53 having an inner surface fitted to the valve body 54 via an O-ring 54b, and an outer diameter screwed to the sleeve 52; Coil 57 and pressing member 59
Is accommodated in the nozzle holder 53, and the cap 55 is screwed onto the male screw of the outer diameter of the nozzle holder 53. The valve body 54 holds a needle valve 56 in its central cavity so as to be axially movable. At the lower end of the valve body 54, a nozzle plate 60 having one small-diameter injection port 61 is provided as shown in an enlarged view in FIG. The fuel injection valve 50 includes a sleeve 52, a nozzle plate 60,
Valve body 54, needle valve 56, spacer 58
The nozzle holder 53 with the exciting coil 57 inserted therein is screwed into the compression spring 51, the pressing member 5
After inserting 9, the cap 55 is screwed and assembled. A hole 59a penetrates through the center of the pressing member 59 so that the high-pressure fuel from the high-pressure fuel pump 3 can pass through the hole 59a.
To the compression spring 51 and the needle valve 56.
Is led to the space that houses the.

Incidentally, FIG. 7 shows a modified example of the nozzle plate 60, and the point that two nozzles 61, 61 are provided is shown in FIG.
Different from the embodiment shown in. Since the engine has a larger displacement than the engine of the embodiment of FIG. 6 and the like, when it is necessary to inject a larger flow rate, two injection holes are provided, and the injection can be performed without reducing the injection speed from the injection holes. .. As a result, as compared with the case where the diameter of the injection port is simply increased, the scattering property after the collision with the piston 11 is excellent and the ignitability is excellent.

Next, the operation of the fuel injection valve 50 will be described. The needle valve 56 is urged downward by the compression spring 51 so that the cone-shaped portion 56a at the lower end is the valve body 54.
Seated on the cone-shaped portion 54a of the
It is designed not to squirt from 1. Excitation pulse is ON
When the exciting coil 57 is excited, the needle valve 56 is pulled upward against the spring force of the compression spring 51 and the fuel pressure, and the needle valve 56 is pulled up until the upper end of the flange portion 56b collides with the lower surface of the spacer 58. The
Held in that position. Even at that position, the flange portion 56b
The space for accommodating the needle valve 56 through the cutout 56c is not closed by the flange portion 56b and maintains the communication. Then, the high-pressure fuel accumulated in the space accommodating the needle valve 56 is ejected from the cone-shaped portions 54a and 56a, and further, the fuel is ejected from the small-diameter injection port 61 of the nozzle plate 60 therebelow. After that, when the excitation of the exciting coil 57 is released, it is returned to the lower side of the needle valve 56 by the urging force of the compression spring 51 and the fuel pressure, the cone-shaped portion 56a seats on the cone-shaped portion 54a, and the high-pressure fuel is ejected. Is stopped.

Next, the operation of the fuel injection valve 50 will be described with reference to FIG. In FIG. 8, the horizontal axis represents the time axis and the vertical axis represents the excitation pulse and the valve lift. When the exciting pulse is turned on to the exciting coil 57, the exciting coil 57 is excited. However, the needle valve 56 is not immediately pulled up, but is pulled up against the spring force of the compression spring 51 and the fuel pressure with a time delay t ₃ (1.5 ms in this example). When the voltage applied to the exciting coil 57 is not constant, the time delay becomes long or short depending on the voltage, and the time until the needle valve 56 is fully opened becomes unstable. As a result, the injection timing into the combustion chamber becomes unstable. After that, the excitation coil 57 is kept excited, and the fully opened state is maintained.

Next, when the excitation pulse is turned off, the excitation of the excitation coil 57 is released, and the needle valve 56 is pulled down by the spring force of the compression spring 51 and the fuel pressure (mainly fuel pressure) to close the valve. In this case, the valve closing delay time t ₄ is short (0.4 ms in this example) and the fuel pressure is relatively stable, so the valve closing delay time t ₄ is more stable than the valve opening delay time t ₃ .

Next, a situation in which fuel is injected from the fuel injection valve 50 will be described with reference to FIGS. 8, 9, 10, and 11. FIG. 10 shows the excitation pulse, the ignition timing, and the opening / closing timing of the exhaust hole and the scavenging hole with respect to the crank angle at low load and low rotation (for example, 700 RPM). FIG. 11 shows that at high load and high rotation. 10 and 11, the rotation direction of the crankshaft is clockwise.

First, when the load is low and the rotation speed is low, the excitation pulse, that is, the valve opening signal is turned on at 7 degrees before top dead center (BTDC), which is a short time after the exhaust hole is closed, and at the ignition timing of the spark plug. It is turned off by a certain BTDC 2 times. Fuel injection valve 5
0 does not open immediately even when receiving a valve opening signal, and time delay t ₃
Open with. Further, the fuel injection valve 50 is closed after a slight time delay t ₄ when the valve opening signal is turned off.

The injection state will be described with reference to FIG.
BTDC7 where piston 11 approaches cylinder head 14
Although the valve opening signal is input every time, the fuel injection valve 50 does not open immediately as described above, but opens with a time delay t ₃ . At the same time when the valve is opened, fuel starts to be injected from the fuel injection valve 50. The injected fuel becomes granular fuel particles and heads for the piston 11. On the other hand, the piston 11 comes closer to the fuel injection valve 50. The state after this process is shown in FIG. 9 (a). Here, the distance from the injection port 61 to the convex portion 11b of the piston 11 is 1
₁ , the distance from the convex portion 11b to the electrode portion 21a is l ₂ (see FIG. 9A), and (l ₁ + l ₂ ) is called the flight distance. After that, the movement of both the injected fuel particles and the piston 11 causes the fuel particles to enter the recess 11 a of the piston 11. Further, the fuel particles further enter and finally collide with the convex portion 11b. After that, the colliding fuel particles are reflected on the entire circumference without adhering to the bottom surface of the recess 11a and scattered in the recess 11a.
Part of it reaches the electrode portion 21a of the spark plug 21 (see FIG. 9).
(b)). Around that time, the ignition of the spark plug will start (Fig. 9 (b)).
). At the same time, the valve opening signal turns off, and the fuel injection valve closes with a slight time delay t ₄ (0.4 ms). Therefore, the fuel injection ends. After that, the end of the injected fuel particles collide with the convex portion 11b, while the spark plug 21 still maintains the spark. The state is shown in FIG. 9 (c). That is, the spark plug 21 continues to fly the spark up to about ATDC 6 degrees, and the fuel particles reflected during this time pass between the electrode portions 21a. Not only at the start of ignition in Fig. 9 (b), but the fuel particles continue to be ignited for a predetermined time after the start of ignition, and the flame gradually spreads around.

The fuel injection valve 50 closes relatively stably in a very short time after the valve opening signal is turned off. Then, since the time from when the valve opening signal is OFF to the ignition start timing is set to a fixed time, which is 0 in this embodiment, at the time of ignition start,
The end of the fuel grain will not be after passing through the spark plug. That is, when ignition is started, the electrode portion 2 of the spark plug 21 is always
Fuel particles are present in 1a. Further, since the maximum combustion pressure of this engine is 50 kg / cm ² at maximum, if the fuel injection pressure is higher than this combustion pressure, the injection timing can be freely set. In such a case, the fuel can be injected after approaching the TDC considerably, so that the fuel particles can be reliably retained in the concave portion 11a of the piston 11 even when the fuel injection amount is small when the load is low. Therefore, ignition can be reliably performed. It should be noted that the OFF time of the valve closing signal may be advanced from the ignition start timing, provided that the end of the fuel particles still reflected at the ignition start timing is not set to complete passing through the electrode portion 21a. .. The details will be described later in the description of FIG. Further, the ignitability can be improved even if the fuel that is reflected even a little before the completion of the ignition discharge passes through the electrode portion 21a. The details will be described later in the description of FIG.
If the reflected fuel passes through the electrode portion 21a during the entire period from the start of ignition to the end of ignition, the ignitability is further improved.
That is, the ignitability can be improved only by setting the reflected fuel to pass through the electrode portion 21a at least during the period from the start of ignition to the completion of the ignition discharge. Also,
Even when the reflected fuel particles are set to pass through the electrode portion 21a after the completion of ignition discharge, the ignitability can be improved by utilizing the residual heat after ignition of the electrode portion 21a.

FIG. 11 shows the excitation pulses A and B, the ignition timing, and the opening / closing timing of the exhaust hole and the scavenging hole with respect to the crank angle at high load and high rotation. At high load and high rotation, unlike the case of low load and low rotation, the ignition timing is BTDC.
It is advanced to 18 degrees, and the fuel injection start timing starts 52 degrees before bottom dead center (excitation pulse A) or before exhaust hole opening (excitation pulse B) before the exhaust hole is closed. This is for injecting a large amount of fuel during the scavenging stroke or before the scavenging stroke. At the time of high load and high rotation, the fuel is injected early, and the combustion chamber is filled with a highly ignitable mixture, and unlike the case of low speed and low load, the reflected fuel particles of the piston 11 are ignited without being ignited. Therefore, it is possible to advance the injection completion time more than the ignition timing. This is an example of the excitation pulse B. At high load and high rotation, the amount of intake air is sufficiently large so that there is no misfire, and the amount of blow-through is not so large.

FIG. 12 shows a modification of the convex portion 11b of the piston 11. Unlike the convex portion 11b of FIG. 3, at the bottom of the concave portion 11a, the combustion chamber 16 gradually increases from the periphery toward the center.
It protrudes to the side and is formed to be highest near the center of the piston 11. In this case, the fuel injection valve 50 and the piston 11 are arranged so that the fuel injected from the fuel injection valve 50 collides with the highest convex portion 11b near the center of the piston 11. The other parts have the same configuration as in FIG.

FIG. 13 is a time chart with the horizontal axis representing the ignition timing, the operating condition of the fuel injection valve 50 and the amount of fuel passing through the electrode portion 21a (per hour) at low speed. 14 and 15 are time charts according to another embodiment. FIG. 16 is a block diagram of an operation control device for the fuel injection valve 50 and the spark plug 21. 17 to 20 are diagrams corresponding to FIG. 9.

The operation control device for the fuel injection valve 50 and the spark plug 21 will be described with reference to FIG. An ECU (electronic control device for fuel injection valve) 80 is a CPU (central processing unit) 8
8 and CDI unit 81. CPU88
Is connected to a crank angle sensor 72 and pulser coils 73 and 74 via an input interface (I / F), and is connected to a throttle sensor 71 for detecting the angle of the throttle valve 19 via an A / D converter. And the information in the memory (map) 89 in which various control amounts are stored in advance according to the operating condition of the engine are compared to control the CDI unit 81 in the ECU 80 and the fuel injection valve 50 outside the ECU 80. .. Here, the CDI unit 81 is composed of a well-known circuit. To be on the safe side, the charge coil 75 is connected to the diode 82, and the capacitor 84 is further provided.
Is connected to the thyristor 86, the capacitor 84 is connected to the ignition coils 91 and 92, and the thyristor 86 is grounded. After the capacitor 84 is charged from the charge coil 75 through the diode 82 and the signal from the pulser coil 74 is processed by the CPU 88, a discharge start signal is applied to the trigger of the thyristor 86, and the charge charged in the capacitor 84 is grounded. Ignition coil 9
A high voltage is excited at 1, 92. Therefore, a high voltage is applied to the spark plug 21, and the spark plug 21 is discharged and ignited. On the other hand, the CPU 88 refers to the information stored in the memory 89 based on the information from the throttle sensor 71, the crank angle sensor 72, and the pulsar coil 73, and then the fuel injection valves 50, 50, 50, 5
Send a drive signal for opening and closing 0.

The spark plug 21 and the fuel injection valve 5 will be described with reference to FIG.
The operation of 0, etc. will be explained over time. Note that the horizontal axis in FIG. 13 is time, and shows the passage of time from left to right in FIG. Capacitor 84 by charge coil 75
Are charged (see (a)). Then, when the CPU 88 sends a discharge start signal (see (b)), the capacitor 84 is immediately grounded, and at the same time, the ignition coil 91.
Then, a high voltage is generated, the electrode portion 21a of the spark plug 21 starts to discharge, and the state is maintained (see (c)). This duration, that is, the discharge time t ₂
And the characteristics of the ignition coil 91. Even if the charging start time is changed, the discharging time t ₂
Changes. Therefore, the charging start time, the capacitor 8
The discharge time can be controlled by selecting the capacitance of No. 4 and the characteristics of the ignition coil 91. The charging start timing can be changed by changing the mounting position of the charge coil 75 around the crankshaft and the characteristics of the charge coil 75.

As described above, the CPU 88 sends a drive signal for opening / closing the fuel injection valve 50 ((d)).
reference). First, when a valve opening signal is sent, the exciting coil 57 is excited and gradually lifts with a valve opening time delay t ₃ ,
Finally fully open. Further, when the time elapses, when the CPU 88 sends a valve closing signal, the exciting coil 57 is deenergized and is fully closed with a slight valve closing delay time t ₄ (see (e)). When the fuel injection valve 50 opens, as described above, the fuel collides with the convex portion 11b and is reflected, and a part of the fuel reaches the electrode portion 21a facing the concave portion 11a. As described with reference to FIG. 9A, the flight distance (l ₁ + l ₂ ) is changed to the flight speed of the fuel (to be precise, due to air resistance, the injection speed from the fuel injection valve 50 is reduced by this air resistance). Speed,
When the time obtained by dividing by the injection speed is also applicable, that is, when the fuel reaches the electrode portion 21a after the flight time t ₅ and the fuel injection valve 50 is closed, the flight time t
After the lapse of _{5, the} passage of fuel through the electrode portion 21a ends. In this embodiment, the discharge period t ₂ is set before and after the entire period in which the fuel passes through the electrode portion 21a. Therefore, the fuel is always ignited at the electrode portion 21a, and irregular combustion does not occur. The relationship between fuel flow and ignition during that time will be described with reference to FIGS. 17 to 20. In FIG.
The states of, and are shown in FIG. 17, FIG. 18, FIG. 19, and FIG.
Equivalent to 0. That is, in FIG. 17, the fuel injection valve 50
Is just before starting the lift. In FIG. 18, the fuel injection valve 50 is fully opened, and the fuel collides with the convex portion 11b and is reflected,
The state is shown in which the tip is just before reaching the electrode portion 21a. At that time, ignition has already started. In FIG. 19, the fuel injection valve 50 is closed, and therefore, the fuel injection from the fuel injection valve 50 has ended, but the already injected fuel successively collides with the convex portion 11b, and the electrode portion 21a Passed, ignited the mixture and was on the verge of explosion. In FIG. 20, the fuel has finished passing through the electrode portion 21a and the spark plug 21 has finished discharging, but since the air-fuel mixture has already been ignited, it completely burns and explodes.

FIG. 14 shows another embodiment of the relative relationship between the fuel injection timing and the spark plug discharge timing. In this figure, only the drive signal to the fuel injection valve 50 and the amount of fuel passing through the electrode portion 21a are shown. In this example, slightly before the discharge start timing fuel finishes passing through the electrode portion 21a i.e. t ₆
It is set before time. Note that t ₂ , t ₄ , and t ₅ are shown in FIG.
It is used with the same meaning as explained in 3.

FIG. 15 shows still another embodiment of the relative relationship between the fuel injection timing and the spark plug discharge timing. Also in this figure, only the drive signal to the fuel injection valve 50 and the amount of fuel passing through the electrode portion 21a are shown. In this embodiment, the discharge end time is set slightly after the fuel starts passing through the electrode portion 21a, that is, before t ₇ hours. Note that t ₃ and t ₅ have the same meanings as described in FIG. 13 and are used.

In both of the embodiments shown in FIGS. 14 and 15, the electrode portion 21a is set to always discharge during at least a part of the period during which the fuel is passing through the electrode portion 21a. That is, the fuel is prevented from passing through before the start of discharge (FIG. 14), or the fuel is prevented from passing through after the end of discharge (FIG. 15). Therefore, the air-fuel mixture is ignited steadily and irregular combustion can be prevented.

In the embodiment of FIG. 15, the fuel is allowed to pass through the electrode portion 21a before the end of the discharge period. However, in the present invention, the fuel passes through the electrode portion 21a after a very short time after the end of the discharge period. It may be set to pass. This is because the electrode portion 21a is at or above the ignition temperature for a very short time after the end of the discharge period.

[0035]

According to the present invention, the fuel can be supplied to the electrode portion of the spark plug even when the fuel injection amount is small at a low speed, and the ignition is performed when the fuel is surely present, so that the fuel can be reliably burned. Therefore, irregular combustion due to misfire can be reduced.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of a fuel injection device in which the present invention is applied to an outboard motor.

FIG. 2 is a vertical cross-sectional view of a crankcase compression type two-cycle internal combustion engine to which the present invention is applied.

FIG. 3 is an enlarged vertical sectional view of a piston, a cylinder head, a fuel injection valve and the like in FIG.

FIG. 4 is a plan sectional view taken along line IV-IV in FIG.

FIG. 5 is a vertical sectional view of only a fuel injection valve.

FIG. 6 is an enlarged vertical sectional view of the vicinity of an injection port of a fuel injection valve.

FIG. 7 is a vertical cross-sectional view showing a modified example of the injection port of the fuel injection valve.

FIG. 8 is a diagram showing a valve lift amount and an excitation pulse of a fuel injection valve.

FIG. 9 is an explanatory view showing how fuel is injected from a fuel injection valve.

FIG. 10 is a diagram showing opening / closing of an exhaust hole and a scavenging hole, an excitation pulse, and an ignition timing at a low load and a low rotation speed.

FIG. 11 is a diagram corresponding to FIG. 10 at the time of high load and high rotation.

FIG. 12 is a vertical cross-sectional view showing a modified example of the convex portion of the piston.

FIG. 13 is a time chart in which the horizontal axis represents the ignition timing, the operating condition of the fuel injection valve 50, and the passing fuel amount (per hour) at the electrode portion 21a at low speed.

FIG. 14 is a time chart according to another embodiment.

FIG. 15 is a time chart according to still another embodiment.

16 is a block diagram of an operation control device for the fuel injection valve 50 and the spark plug 21. FIG.

FIG. 17 is an explanatory diagram showing how fuel is injected from a fuel injection valve.

FIG. 18 is an explanatory diagram showing how fuel is injected from a fuel injection valve.

FIG. 19 is an explanatory view showing how fuel is injected from a fuel injection valve.

FIG. 20 is an explanatory diagram showing how fuel is injected from a fuel injection valve.

[Explanation of symbols]

 10 ... Crank chamber compression type 2-cycle internal combustion engine 11 ... Piston 11a ... Recess 11b ... Convex 13 ... Cylinder 14 ... Cylinder head 16 ... combustion chamber 21 ... spark plug 21a ... spark plug electrode 22 ... exhaust passage 23 ... scavenging passage 50 ... fuel injection valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location F02D 43/00 301 J 8109-3G F02M 61/14 310 S 7226-3G 69/04 P 9248-3G 69/10 9248-3G F02P 5/15 A 9150-3G 13/00 301 A 8923-3G 303 A 8923-3G

Claims (4)

[Claims] 1. An in-cylinder fuel injection type two-cycle internal combustion engine having a cylinder head equipped with a fuel injection valve and an ignition plug,
A recess is provided on the top combustion chamber side of the piston, and a projection projecting toward the combustion chamber is provided on the recess, and the electrode portion of the spark plug is exposed in the recess near the projection, while the fuel injection is performed. The fuel injection direction of the valve is directed to the convex portion, and the fuel injection direction is arranged so that the fuel toward the convex portion collides with the convex portion and then is reflected and toward the electrode portion, while low speed is applied. While setting the opening / closing timing of the fuel injection valve and the ignition timing of the spark plug near the top dead center of the piston,
A cylinder characterized in that the opening / closing timing of the fuel injection valve and the ignition timing of the spark plug are controlled so that at least a part of the fuel toward the electrode portion passes while the electrode portion is discharging. Internal fuel injection type 2-cycle internal combustion engine. 2. A cylinder fuel injection type two-cycle internal combustion engine having a fuel injection valve and a spark plug in a cylinder head,
A recess is provided on the top combustion chamber side of the piston, and a projection projecting toward the combustion chamber is provided on the recess, and the electrode portion of the spark plug is exposed in the recess near the projection, while the fuel injection is performed. The fuel injection direction of the valve is directed to the convex portion, and the fuel injection direction is arranged so that the fuel toward the convex portion collides with the convex portion and then is reflected and toward the electrode portion, while low speed is applied. While setting the opening / closing timing of the fuel injection valve and the ignition timing of the spark plug near the top dead center of the piston,
From the flight time from the time when the fuel is actually injected from the fuel injection valve to the time when the fuel is reflected by the convex portion and reaches the electrode portion, and the valve closing instruction timing for instructing the valve closing of the fuel injection valve, The discharge start timing at which the spark plug starts discharge is set earlier than the timing of adding the valve closing delay time until the fuel injection valve actually closes to the valve closing instruction timing. In-cylinder fuel injection two-cycle internal combustion engine. 3. An in-cylinder fuel injection type two-cycle internal combustion engine having a cylinder head provided with a fuel injection valve and an ignition plug,
A recess is provided on the top combustion chamber side of the piston, and a projection projecting toward the combustion chamber is provided on the recess, and the electrode portion of the spark plug is exposed in the recess near the projection, while the fuel injection is performed. The fuel injection direction of the valve is directed to the convex portion, and the fuel injection direction is arranged so that the fuel toward the convex portion collides with the convex portion and then is reflected and toward the electrode portion, while low speed is applied. While setting the opening / closing timing of the fuel injection valve and the ignition timing of the spark plug near the top dead center of the piston,
From the flight time from the time when the fuel is actually injected from the fuel injection valve to the time when the fuel is reflected by the convex portion and reaches the electrode portion, and the valve opening instruction timing for instructing the valve opening of the fuel injection valve, From the timing of adding the valve opening delay time until the fuel injection valve actually opens and the valve opening instruction time,
An in-cylinder fuel injection type two-cycle internal combustion engine characterized in that a discharge end timing at which the spark plug ends discharge is set to be late. 4. An in-cylinder fuel injection type two-cycle internal combustion engine having a cylinder head equipped with a fuel injection valve and an ignition plug,
A scavenging hole and an exhaust hole are opened so as to face the cylinder surface on which the piston slides, and a plane connecting the outer peripheral edges of the scavenging hole and the outer peripheral edges of the exhaust hole. In addition, the in-cylinder fuel injection type two-cycle internal combustion engine is characterized in that the fuel injection valve and the ignition plug are arranged in a space sandwiched between two planes parallel to the cylinder center axis.