JPH1089066A - Cylinder fuel injection-type two-cycle engine for outboard engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder fuel injection-type two-cycle engine for an outboard engine, in which the degree of requirements for heat resistance is low, the degree of freedom of the arranging position of an exhaust control valve is high, and the structure is not complicated. SOLUTION: In a two-cycle engine, fuel is injected and supplied into a combustion chamber by a fuel injection valve, ignited by an ignition plug, and burnt, and exhaust gas is discharged into water through an exhaust passage communicated with exhaust ports 41 opening to cylinders 21, and opening to water. An auxiliary exhaust passage 45 communicated with the atmosphere is connected to the way of the exhaust passage 16, and an exhaust control valve 43 for changing the passage area is arranged in the auxiliary exhaust passage 45.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder injection two-stroke engine for an outboard motor, which injects and supplies fuel (gasoline) into a combustion chamber.

[0002]

2. Description of the Related Art Conventionally, fresh air is introduced into a crank chamber through an intake passage provided with a throttle valve and is primarily compressed, and the inside of a cylinder is scavenged by the primary compressed fresh air, while being disposed on a combustion chamber wall. Fuel (gasoline) is injected from the fuel injection valve during the scavenging and exhaust strokes and further during the compression stroke, and is ignited by a spark plug through the compression stroke and burned.
An in-cylinder injection two-cycle engine has been proposed in which burned gas is discharged from a combustion chamber to an exhaust passage prior to the next scavenging stroke.

In a two-stroke engine, particularly in a low-speed rotation and low-load operation range, the amount of fresh air itself for scavenging is small, and accordingly, the in-cylinder pressure decreases, and the burned gas in the exhaust passage becomes in the cylinder. There is a problem that irregular combustion is liable to occur because of the following reasons: the fuel flows backward, the injected fuel is diffused to lower the fuel concentration, and the temperature in the cylinder is low, so that flame propagation hardly occurs.

Therefore, the present inventors have arranged an exhaust control valve for variably controlling the exhaust passage area in a direct injection type two-stroke engine. In the low speed rotation and low load operation range, the exhaust control valve is used. By reducing the pressure, the pressure at the start of compression and the temperature in the cylinder are kept high, and the generation of irregular combustion has been developed. The exhaust control valve is supplied with fuel by injecting fuel into a combustion chamber by a fuel injection valve, ignited and burned by an ignition plug, and communicates exhaust gas with an exhaust port opened in a cylinder through an exhaust passage opened in water. It is conceivable to dispose it in a two-cylinder in-cylinder injection engine for an outboard motor that discharges water.

[0005]

The above-mentioned exhaust control valve has a function of restricting the outflow of exhaust gas from the cylinder by increasing the flow path resistance of the exhaust passage, and this function is sufficiently ensured. For this purpose, it is considered effective to dispose the exhaust control valve near the cylinder opening of the exhaust passage. However, in order to arrange it near the cylinder opening of the exhaust passage, a structure that can withstand high temperatures is necessary.
There is also a problem that the degree of freedom in the arrangement position is small, and the structure tends to be complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and requires only a low heat resistance requirement, has a high degree of freedom in the arrangement position of an exhaust control valve, and has no complicated structure. It is an object to provide a direct injection type two engine.

[0007]

According to a first aspect of the present invention, fuel is injected and supplied into a combustion chamber by a fuel injection valve, ignited and burned by a spark plug, and exhaust gas is communicated with an exhaust port opened to a cylinder. In an in-cylinder injection two-stroke engine for an outboard motor, the auxiliary exhaust passage communicating with the atmosphere is connected in the middle of the exhaust passage. It is characterized in that an exhaust control valve for changing the passage area is disposed in the inside.

According to a second aspect of the present invention, in the first aspect, exhaust pressure detecting means for detecting a pressure in the exhaust passage downstream of the exhaust port and substantially upstream of the exhaust control valve, When the detected exhaust pressure value detected by the exhaust pressure detecting means is larger than a reference exhaust pressure value set in accordance with the operating state, the opening degree of the exhaust control valve is increased, and the detected exhaust pressure value is adjusted to the reference exhaust pressure value. An exhaust control valve opening control means for reducing the opening of the exhaust control valve when the exhaust pressure is smaller than the exhaust pressure value is provided.

According to a third aspect of the present invention, in the first or second aspect, the underwater opening of the exhaust passage is connected to a rear side of the underwater immersion member that is immersed in the outboard motor during navigation. It is characterized in that it is arranged at a site where

According to a fourth aspect of the present invention, in any one of the first to third aspects, an exhaust expansion chamber is formed in the middle of the exhaust passage, and the auxiliary exhaust passage is connected to the exhaust expansion chamber. .

According to a fifth aspect of the present invention, in the fourth aspect, the outboard motor has an anti-capitation plate for preventing air from being trapped in a propeller for propulsion, and the anti-caption plate in the auxiliary exhaust passage is provided. The exhaust control valve is characterized in that the exhaust control valve is disposed at a position closer to a tilt axis, which is a swing axis of the outboard motor when viewed from above and vertically.

[0012]

As described above, the exhaust control valve serves to change the flow resistance of the exhaust passage to change the difficulty of the exhaust gas flowing out of the cylinder. Regardless of the position of the valve in the exhaust passage, the above function can be ensured by optimizing the degree of restriction. On the other hand, the operating range in which the operation of the exhaust control valve is effective is the low-speed, low-load operating range including the idling operating range. In the case of an underwater exhaust type engine for an outboard motor, most of the exhaust gas Is discharged into the air from the auxiliary exhaust passage.

According to the first aspect of the present invention, an exhaust control valve for connecting an auxiliary exhaust passage communicating with the atmosphere in the middle of an exhaust passage opening into water, and variably controlling the area of the passage in the auxiliary exhaust passage is provided. Since the exhaust control valve is disposed, that is, the exhaust control valve is disposed in a portion of the auxiliary exhaust passage that is generally away from a high-temperature portion near the cylinder opening of the exhaust passage, so that it is not necessary to increase the heat resistance of the exhaust control valve. There is an effect that the degree of freedom in position is increased and the structure of the exhaust control valve and its surroundings can be simplified.

According to the second aspect of the invention, when the detected exhaust pressure value in the exhaust passage is larger or smaller than the reference exhaust pressure value, the opening of the exhaust control valve is controlled to be larger or smaller. So
In particular, the exhaust gas discharge resistance in the low-speed rotation low-load operation range can be increased, the pressure at the start of compression and the temperature in the cylinder can be kept high, and the generation of irregular combustion can be suppressed.

Further, even if the operating environment such as weather conditions changes, the load capacity changes, the amount of submersion of the outboard motor changes, and the back pressure to the exhaust passage changes due to the change in the opening position in the water. The outflow of the burned gas from the exhaust port can always be kept in the most desirable state.

According to the third aspect of the present invention, since the underwater opening of the exhaust passage is provided at a position behind the underwater immersion member during forward navigation, the underwater opening is shaded by the underwater immersion member, and the underwater opening is negative during high speed navigation. Therefore, a negative pressure acts on the exhaust passage, and the pressure at the connection portion of the auxiliary exhaust passage decreases. For this reason, the burned gas flow having a high temperature flowing into the auxiliary exhaust passage is reduced, or the atmosphere flows into the auxiliary exhaust passage. This reduces the need to increase the heat resistance of the exhaust control valve.

According to the fourth aspect of the present invention, since the auxiliary exhaust passage is connected to the exhaust expansion chamber, the temperature of the burned gas passing through the auxiliary exhaust passage during low load or low speed navigation is reduced in the exhaust expansion chamber. Therefore, the necessity of increasing the heat resistance of the exhaust control valve is reduced.

According to the fifth aspect of the present invention, since the exhaust control valve can be positioned above the water surface, when the outboard motor is used at sea, the exhaust control valve does not sink in seawater. . Thus, it is possible to prevent the exhaust control valve from malfunctioning due to the corrosive action of the salt.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIGS. 1 to 8 are views for explaining a direct injection two-stroke engine according to a first embodiment of the present invention. FIGS. 1 and 2 show a left side of an outboard motor employing the engine of the present embodiment. 3 is a sectional rear view of the engine, FIG. 4 is a block diagram of the operation control device, FIG. 5 is a conceptual diagram of the engine, and FIG. 6 is a flowchart for explaining the control operation. FIG. 7 is a conceptual diagram of the control map data, and FIG. 8 is a conceptual diagram of the reference exhaust pressure value map data.

In FIG. 1, reference numeral 1 denotes an outboard motor employing the engine of this embodiment, which is pivotally supported on a stern 2a of the hull 2 via a swivel arm 9 and a clamp bracket 8 so as to be able to swing up and down around the tilt shaft 100. During cranking, the crankshaft 20 is positioned vertically so as to be substantially vertical.

In the outboard motor 1, an upper case 5 is connected to an upper part of a lower case 4 in which a propelling propeller 3 is disposed.
An engine 6 is mounted on an upper part of the upper case 5 and has a schematic structure in which the periphery of the engine 6 is surrounded by a top cowl 7. The rotation of the engine 6 is controlled by an output shaft 6a connected to a crankshaft 20, a drive shaft 12 extending vertically, a bevel gear mechanism 10, and a propulsion shaft 11 extending horizontally.
Is transmitted to the propeller 3 via the.

Reference numeral 101 denotes an anti-capitation plate for preventing air from getting into the propeller 3, which is provided on the upper part of the lower case 4. The mounting position of the outboard motor 1 on the stern 2 is set such that the anti-capitation plate 101 is slightly (for example, several centimeters) below the bottom of the ship. As a result, even during high-speed navigation, the anti-capitation plate 101 is always submerged, and has a shape that covers the front upper part of the propeller 3 so that the atmosphere is not trapped in the front negative pressure part of the propeller 3.

The engine 6 is a water-cooled V-type 6-cylinder in-cylinder injection two-cycle engine.
And a cylinder body 23 in which six cylinders (cylinder bores) 21 are arranged so as to form a V bank, and a cylinder head 24 is mounted on the cylinder body 23. It has a schematic structure in which a piston 25 slidably inserted into each cylinder 21 is connected to the crankshaft 20 via a connecting rod 26.

An ignition plug 27 is screwed into the cylinder head 24. The electrode of the ignition plug 27 faces a combustion chamber surrounded by the cylinder head 24, the cylinder 21 of the cylinder body 23, and the piston 25. . The ignition plug 27 is driven by an ignition circuit 63 (see FIG. 4) and generates a spark in the combustion chamber at a predetermined timing.

The intake system of the engine 6 is configured as follows. Each opening 22b is formed in the crankcase 22 so as to communicate with each crank chamber 22a defined corresponding to each cylinder, and the intake passage 30 is connected to each opening 22b with a reed valve 32 interposed therebetween. A throttle body 3 having a throttle valve 31 built in upstream of the intake passage 30;
3 is connected. The throttle valve 31 is opened and closed by a throttle actuator 61 (see FIG. 4).

Further, one opposed scavenging passage 35a and two main scavenging passages 35b and 35c are formed in the cylinder body 23 to communicate each crank chamber 22a and each cylinder 21, and scavenging ports of the scavenging passages 35a to 35c are formed. 35 to cylinder 21
Open inside.

A fuel injection valve 49 is mounted on the side wall of the cylinder body 23 for each cylinder 21. Although not shown, the fuel injection valve 49 is connected to a fuel supply rail provided with a pressure regulating valve having a return passage at the distal end, and high-pressure fuel is supplied to the fuel supply rail from a fuel pump. ing. When the injection nozzle is opened by moving the valve body of the fuel injection valve 49 by a built-in electromagnetic coil 62 (see FIG. 4), the high-pressure fuel is injected and supplied into the cylinder 21 during the period when the nozzle is open. .

The exhaust system of the engine 6 is configured as follows. An exhaust branch passage (independent passage) 42 communicating with an exhaust port 41 opened to each cylinder 21 is formed in the cylinder body 23, and each exhaust branch passage 42 is formed to extend in a vertical direction substantially parallel to the crankshaft 20. The exhaust gas is merged into the exhaust merging passages 40 of the respective banks, and the lower end exhaust ports 6 b of the respective exhaust merging passages 40 are opened on the lower surface of the cylinder body 23.

An exhaust guide 13 is connected to the lower surface of the cylinder body 23, and a pair of exhaust holes 13a, 13b, which communicate with the exhaust guide 13 at the lower end exhaust ports 6b.
13a, and a downwardly extending exhaust pipe 14 communicating with each exhaust hole 13a is connected. Further, a muffler 16 surrounding the exhaust pipe 14 and forming an exhaust expansion chamber is connected to the exhaust guide 13, and the muffler 16 The lower end of the lower case 4
Open into water inside. In this way, an exhaust passage for discharging exhaust gas from each cylinder into water is formed.

The muffler 16 is connected to an auxiliary exhaust passage 45 for exhausting the exhaust gas in the exhaust passage to the atmosphere mainly in a low-load, low-speed operation range such as when idling. A valve chamber 45a is formed in the exhaust passage 45, and a butterfly exhaust control valve 43 for variably controlling the area of the auxiliary exhaust passage is provided in the valve chamber 45a. The exhaust control valve 43 is driven to open and close by an actuator 64 (see FIG. 4) composed of a servomotor.

The end on the muffler 16 side and the end on the open air side of the auxiliary exhaust passage 45 are both provided at positions above the water surface. That is, the tilt shafts 1 at both end positions
The distance L2 in the height direction to the anti-caption plate 101 at both ends is larger than the distance L1 in the height direction up to 00. For this reason, even if the load on the ship increases, both ends are located above the outer water surface, and the outside water does not enter the auxiliary exhaust passage 45 from both ends. Even when the heights of both ends are set closer to the anti-capitation plate 101, if the position of the exhaust control valve 43 is set so as to satisfy L1 <L2, the exhaust control valve 43 falls below the outer water level and is submerged. Never.

That is, as described above, the anti-capitation plate 101 is slightly lower (for example, several centimeters) below the ship bottom, while the tilt shaft 100 is slightly (for example, 0 to several centimeters) below the upper end of the stern 2a. It is assumed to be upward. As the loading capacity of the ship increases, the height from the water surface to the upper end of the hull 2 decreases. The maximum loading capacity is determined so that waves during navigation do not exceed the upper end of the hull 2. Since the approximate height from the water surface to the upper end of the stern 2a when the maximum loading capacity is mounted, that is, from the water surface to the upper end of the stern 2a, is half of the height from the bottom of the ship to the upper end of the stern 2a, L1
Since the position satisfying <L2 is always above the water surface regardless of the load amount, it is possible to prevent the exhaust control valve 43 from being submerged.

The muffler 16 has an exhaust pressure for detecting an exhaust pressure (back pressure) downstream of the exhaust port 41 and substantially upstream of the exhaust control valve 43 in the exhaust passage. The sensor 55 is mounted. The exhaust pressure sensor 55 is connected to the muffler 16 from outside the upper case 5.
The detection portion of the sensor 55 is located in the muffler 16 near the downstream end opening of the exhaust pipe 14.

The connection position of the auxiliary exhaust passage 45 is not limited to the muffler 16 in which the pressure and the temperature of the burned gas is reduced. Any position may be used as long as the pressure can be prevented from being abnormally high when viewed from the operating state. For example, the pressure may be connected to a merging passage 40 shown by a two-dot chain line in FIG.

The connection position of the exhaust pressure sensor 55 is not limited to the muffler 16, but may be any position as long as the pressure in the exhaust passage can be detected.
For example, it may be connected to a merging passage 40 shown by a two-dot chain line in FIG.

In FIG. 4, reference numeral 50 denotes an ECU for controlling the operation of the engine 6, and detection signals indicating the operating state of the engine and the like are input from various sensors to the ECU 50. For example, an engine speed signal REV from a speed sensor 51, an accelerator opening (pressing amount of an accelerator lever) signal ACC from an accelerator opening sensor 52, an engine coolant temperature signal TW from a water temperature sensor 53, a crank angle sensor 54 From the crank angle (piston position) CA,
Exhaust pipe pressure (back pressure) P from the exhaust pressure sensor 55
E, a crank chamber pressure signal from the crank chamber pressure sensor 56, an atmospheric pressure signal from the atmospheric pressure sensor 57, an atmospheric temperature signal from the atmospheric temperature sensor 58, and the like are input.

The ECU 50 executes various types of control maps stored in the data storage device in accordance with a preset program based on each detection signal indicating the engine operating state input from each of the sensors. And outputs various control signals to various actuators. For example, a throttle valve opening signal TH to a throttle actuator 61 for opening and closing the throttle valve 31, a fuel injection period (amount) signal FD to an electromagnetic coil 62 for opening and closing the fuel injection valve 49, and a fuel injection start timing signal INJ. , An ignition signal IGN to an ignition circuit 63 that supplies a high-voltage current to the ignition plug 27, and an exhaust control valve opening signal EX to an actuator 64 that drives the exhaust control valve 43 to open and close.
V or the like is output.

The opening of the throttle valve 31 and the opening of the exhaust control valve 43 are determined by a throttle opening sensor (not shown).
The detected opening is detected by an exhaust control valve opening sensor, and the detected opening is fed back to the ECU 50.

Here, the ECU 50 has the following functions. [Exhaust Control Valve Opening Control Function] In a normal (steady state) operating state of the engine, the opening EXV of the exhaust control valve 43 is set based on one or both of the accelerator opening ACC and the engine speed REV. -Control to the rotation speed-based exhaust control valve opening EXVo.

In the start operation state or the warm-up operation state,
The opening control is performed to increase the opening to a value larger than the accelerator-based exhaust control valve opening EXVo. In this case, the increment of the exhaust control valve opening is controlled to be larger as the engine cooling water temperature is lower, and the exhaust control valve opening during warm-up operation is controlled by the accelerator / rotation speed-based exhaust control valve opening and the starting exhaust control valve. The size is controlled between the opening degree.

In an idling operation state in which the accelerator opening is smaller than a predetermined idling opening, the exhaust control valve opening is controlled to be smaller than the accelerator reference exhaust control valve opening when the engine speed is higher than the target idling speed. When it is low, the control is large.

In the transient operation state, the opening of the exhaust control valve is controlled to be larger than the opening of the accelerator / rotation speed reference exhaust control valve. In the transient operation state (sudden acceleration state), the larger the one or both of the accelerator opening and the time increase rate of the engine speed are, the larger the increase of the exhaust control valve is controlled. In this case, the larger the opening degree of the exhaust control valve is, the larger the operating range where the Alcell opening and the engine speed are smaller is controlled.

In the rapid deceleration state, the closing speed of the exhaust control valve is made slower as one or both of the accelerator opening and the time reduction rate of the engine speed are larger, so that the opening of the exhaust control valve is reduced to the accelerator / rotation speed based exhaust. Make it larger than the control valve opening.

[Fuel Injection Amount Correction Function] In a start operation state or a warm-up operation state, the fuel injection amount is increased from an accelerator reference injection amount corresponding to the accelerator opening.

In the idling operation state, the fuel injection amount is decreased when the engine speed is higher than the target idling speed, and is increased when the engine speed is lower than the target idling speed.

[Throttle Valve Opening Correction Function] In the starting operation state or the warm-up operation state, the throttle valve opening is increased from the accelerator reference throttle valve opening corresponding to the accelerator opening.

Next, the control operation of the exhaust control valve opening by the ECU 50 will be described mainly with reference to FIG. When the control is started by turning on the main switch, the engine speed REV and the accelerator opening ACC are read, and the engine operating state is changed from the engine speed-accelerator opening-control parameter map having the structure shown in FIG. Corresponding ignition timing IGN, fuel injection start timing INJ, fuel injection amount F
D, the initial values of the exhaust control valve opening EXV and the throttle valve opening TH are read, and the fuel injection valve driving electromagnetic coil 62,
The ignition plug ignition circuit 63, the throttle valve actuator 61, and the exhaust control valve actuator 64 operate to obtain the read control values (steps S1 to S3).

Subsequently, the engine speed REV, the accelerator opening ACC, and the exhaust pressure value (detected back pressure value) PE from the exhaust pressure sensor 55 are read, and if the REV and ACC have not changed from the previous time. FIG. 8 shows a reference back pressure value PEo corresponding to the engine speed REV and the accelerator opening ACC.
Are read from the REV-ACC-PEo map having the structure shown in FIG.

The detected back pressure value PE is equal to the reference back pressure value P.
In the same case as Eo, the ignition timing IG read in step S2 without changing the opening of the exhaust control valve.
Each actuator operates with N, the fuel injection amount FD, and the like as target values (step S8). On the other hand, the detected back pressure value PE
Is larger than the reference back pressure value PEo, the opening EXV of the exhaust control valve 43 is increased (step S10). Conversely, if PE is smaller than PEo, the opening EXV of the exhaust control valve 43 is increased. Each actuator is operated with the ignition timing IGN, the fuel injection amount FD, and the like read in step S2 as target values (step S8).

As described above, in this embodiment, the auxiliary exhaust passage 45 is connected in the middle of the muffler (exhaust passage) 16, and the exhaust control valve 43 for variably controlling the area of the auxiliary exhaust passage 45 is disposed in the auxiliary exhaust passage 45. That is, the exhaust control valve 43 is
Since the auxiliary exhaust passage 45 is disposed in a portion of the exhaust passage near the cylinder opening (exhaust port 41) of the exhaust passage and away from the high-temperature portion, the exhaust control valve 43 may be a simple butterfly type, and its heat resistance is increased. It is unnecessary and has a simple structure. Further, as conceptually shown in FIG. 5, the degree of freedom in the arrangement position is large, and the structure can be simplified from this point as well.

When the detected back pressure value PE is larger or smaller than the reference back pressure value PEo, the opening EXV of the exhaust control valve 43 is controlled to be larger or smaller. In particular, by increasing the exhaust gas discharge resistance in the low-speed rotation and low-load operation range, the pressure at the start of compression and the temperature in the cylinder are kept high.
The occurrence of irregular combustion can be suppressed. Also, even if the operating environment such as weather conditions changes, the loading capacity changes, the amount of submersion of the outboard motor changes, and the back pressure to the exhaust passage changes due to the change in the opening position in the water, the exhaust port will Of the burned gas can be always maintained in the most desirable state.

Here, in the first embodiment, the exhaust control valve opening EXV is increased or decreased stepwise by a predetermined opening depending on whether the detected back pressure value PE is larger or smaller than the reference back pressure value PEo. However, the exhaust control valve opening EXV may be controlled according to the magnitude of the difference ΔPE between the two back pressure values, and the fuel injection amount FD and the fuel injection start timing IN may be further controlled according to the magnitude of ΔPE.
J and the throttle opening TH are also desirably variably controlled.
9 and 10 show a second embodiment of the present invention in which such control is performed.

In FIG. 9, when the control is started, the engine speed REV, the accelerator opening ACC, and the exhaust passage pressure (back) detected by the rotation speed sensor 51, the accelerator opening sensor 52, and the exhaust pressure sensor 55. Pressure) PE is read (step S1), and various reference values corresponding to the engine speed and accelerator opening, for example, a reference back pressure value PEo (see FIG. 8) and a reference fuel injection amount FD are obtained from various built-in maps.
o, a reference fuel injection start timing INJo, a reference throttle valve opening THo, a reference exhaust control valve opening EXVo, a reference ignition timing IGNo, and the like are obtained (step S2).

Next, a difference ΔPE = PEo−PE between the detected back pressure value PE and the reference back pressure value PEo is obtained (step S3), and the ΔPE is applied to FIGS. 10 (a) to 10 (d). As a result, the fuel injection amount correction value ΔFD, the fuel injection start timing correction value ΔINJ, the throttle valve opening correction value Δ
TH and the exhaust control valve opening correction value ΔEXV are obtained (step S4).

Subsequently, the fuel injection amount FD, the fuel injection start timing INJ, the throttle valve opening TH, and the exhaust control valve opening EXV are changed to the reference values FDo, INJo, THo,
And EXVo, the above correction values ΔFD, ΔINJ, ΔT
H, ΔEXV are calculated by subtracting them (step S5), and each actuator is controlled so that these values are obtained (step S6).

For example, as shown in the left area of FIG. 10A, when ΔPE is negative (back pressure is high), the fuel injection amount correction value ΔFD becomes positive, and the fuel injection amount FD becomes the reference value F.
Do is decreased by ΔFD. As a result, if the amount of fresh air introduced into the combustion chamber is reduced due to the back pressure being higher than the standard, the fuel injection amount is reduced in accordance with this decrease in fresh air, and the amount of fresh air is reduced. The resulting deviation of the air-fuel ratio from the target value to the rich side is suppressed.

On the other hand, as shown in the right area of FIG. 10 (a), when ΔPE is positive (back pressure is low), the fuel injection amount correction value ΔFD becomes negative, and the fuel injection amount FD becomes the reference value FDo. The amount is further increased by ΔFD. As a result, if the amount of fresh air introduced into the combustion chamber increases due to the back pressure being lower than the reference, the amount of fuel is increased in accordance with the increase in the amount of fresh air. Deviation is suppressed.

As shown in the left area of FIG. 10B, when ΔPE is negative (back pressure is high), the fuel injection start timing correction value ΔINJ is positive, and the fuel injection start timing INJ is higher than the reference value INJo. It is retarded by ΔINJ. As a result of delaying the fuel injection start timing in this way, the amount of fuel blow-through decreases, the unburned component (HC) in the exhaust gas decreases, the exhaust gas properties become better, and the fuel efficiency improves.

In this case, as described with reference to FIG. 10A, the fuel injection amount is reduced because the back pressure is higher than the reference, so that the mixing required for combustion even if the fuel injection start timing is delayed. Qi formation is possible.

As shown in the right region of FIG. 10B, when ΔPE is positive (back pressure is low), the fuel injection start timing correction value ΔINJ is negative, and the fuel injection start timing INJ is higher than the reference value INJo. It is advanced by ΔINJ. As a result, as described with reference to FIG. 10A, when the fuel injection amount is increased because the back pressure is lower than the reference, the atomization time necessary for the increased fuel can be secured.

As shown in the left area of FIG. 10 (c), when ΔPE is negative (back pressure is high), the throttle valve opening correction value ΔTH is negative, and the throttle valve opening TH is smaller than the reference value THo. It increases by ΔTH. As a result, the decrease in the amount of fresh air introduced into the combustion chamber due to the back pressure being higher than the standard is suppressed by the increase in the throttle valve opening, and the target air-fuel ratio due to the decrease in the amount of fresh air is reduced. The deviation from the value is suppressed.

On the other hand, as shown in the right area of FIG. 10 (c), when ΔPE is positive (back pressure is low), the throttle valve opening correction value ΔTH is positive, and the throttle valve opening TH is a reference value. It becomes smaller than the value THo by ΔTH. As a result, an increase in the amount of fresh air introduced into the combustion chamber due to the back pressure being lower than the reference is suppressed by a decrease in the throttle valve opening, and the target air-fuel ratio due to the increase in the amount of fresh air is suppressed. The deviation from the value is suppressed.

As shown in the left area of FIG. 10D, when ΔPE is negative (back pressure is high), the exhaust control valve opening correction value ΔEXV becomes negative, and the exhaust control valve opening EXV becomes the reference value. It becomes larger than EXVo by ΔEXV. As a result, the decrease in the amount of fresh air introduced into the combustion chamber due to the back pressure being higher than the standard is suppressed by this increase in the exhaust control valve opening, and the air-fuel ratio resulting from the decrease in the amount of fresh air is reduced. Is suppressed from the target value.

On the other hand, as shown in the right region of FIG. 10D, when ΔPE is positive (back pressure is low), the exhaust control valve opening correction value ΔEXV becomes positive, and the exhaust control valve opening E
XV becomes smaller than the reference value EXVo by ΔEXV. As a result, an increase in the amount of fresh air introduced into the combustion chamber due to the back pressure being lower than the reference is suppressed by the decrease in the opening degree of the exhaust control valve, and the air-fuel ratio resulting from the increase in the amount of fresh air is reduced. Is suppressed from the target value.

[Brief description of the drawings]

FIG. 1 is a left side view of an outboard motor including an in-cylinder injection two-cycle engine according to a first embodiment of the present invention.

FIG. 2 is a sectional plan view of the outboard motor according to the first embodiment.

FIG. 3 is a sectional rear view of the engine according to the first embodiment.

FIG. 4 is a block diagram of a control device of the engine according to the first embodiment.

FIG. 5 is a schematic diagram of the engine of the first embodiment.

FIG. 6 is a flowchart illustrating a control operation of the engine according to the first embodiment.

FIG. 7 is a diagram conceptually showing control data of the engine of the first embodiment.

FIG. 8 is a diagram conceptually showing control data of the engine of the first embodiment.

FIG. 9 is a flowchart illustrating a control operation of the engine according to the second embodiment of the present invention.

FIG. 10 is a diagram conceptually showing control data of the engine according to the second embodiment.

[Explanation of symbols]

 Reference Signs List 6 in-cylinder injection two-cycle engine for outboard motor 16 muffler (exhaust passage) 21 cylinder 27 spark plug 41 exhaust port 43 exhaust control valve 45 auxiliary exhaust passage 49 fuel injection valve 50 ECU (exhaust control valve opening control means) 55 Exhaust pressure detection sensor EXV Exhaust control valve opening PE Detected exhaust pressure value PEo Standard exhaust pressure value

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 9/04 B63H 21/26 N

Claims (5)

[Claims] A fuel is injected and supplied into a combustion chamber by a fuel injection valve, ignited by a spark plug and burned, and
An in-cylinder injection type two-stroke engine for an outboard motor in which exhaust gas is communicated with an exhaust port opened to a cylinder and discharged into the water through an exhaust passage opened to the water. An in-cylinder injection two-stroke engine for an outboard motor, comprising: an auxiliary exhaust passage connected to the engine; and an exhaust control valve for changing a passage area in the auxiliary exhaust passage. 2. The exhaust system according to claim 1, wherein
Exhaust pressure detecting means for detecting a pressure downstream of the exhaust port and substantially upstream of the exhaust control valve; and a detected exhaust pressure value detected by the exhaust pressure detecting means set in accordance with an operating state. When the detected exhaust pressure value is smaller than the reference exhaust pressure value, the opening degree of the exhaust control valve is increased. An in-cylinder injection two-stroke engine for an outboard motor, comprising a degree control means. 3. The underwater opening of the exhaust passage according to claim 1, wherein the opening located underwater in the exhaust passage is disposed at a position on the rear side of the underwater immersion member that is immersed in the water when the outboard motor travels. An in-cylinder injection two-stroke engine for an outboard motor. 4. The outboard motor cylinder according to claim 1, wherein an exhaust expansion chamber is formed in the exhaust passage, and the auxiliary exhaust passage is connected to the exhaust expansion chamber. Internal injection two-cycle engine. 5. The outboard motor according to claim 4, wherein the outboard motor has an anti-caption plate for preventing air from being caught in a propeller for propulsion, while the auxiliary exhaust passage is above the anti-capitation plate and An in-cylinder injection two-stroke engine for an outboard motor, wherein the exhaust control valve is disposed near a tilt axis, which is a swing axis of the outboard motor when viewed in a vertical direction.