JPH1113526A - Fuel injection engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the blowout of fuel from an exhaust port to the minimum so as to securely maintain a running state and reduce variations in fuel injection quantity before start of running. SOLUTION: In a fuel injection engine 3 mounted on a small-sized ship, a first fuel injection valve 16 for injecting fuel over substantially all regions of engine speeds and a second fuel injection valve 17 for injecting fuel in at least part of the regions of the engine speeds substantially higher than or equal to a running starting engine speed are disposed in each cylinder. Consequently, since the fuel is injected from both the first and second fuel injection valves 16, 17 in the region of the engine speed higher than or equal to the running starting engine speed, a reduced fuel injection quantity is sufficient in each of the first and second fuel injection valves 16, 17 with respect to a required fuel injection quantity, thus suppressing the blowout of the fuel from an exhaust port to the minimum so as to securely maintain a running state. Furthermore, a fuel injection time of the first fuel injection valve 16 is set longer before the start of running, thereby reducing variations in fuel injection quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection engine mounted on a small boat which shifts from a non-sliding state to a sliding state when the engine speed exceeds a sliding start engine speed.

[0002]

2. Description of the Related Art Conventionally, in a fuel injection type engine mounted on a small boat such as a watercraft, one fuel injection valve for injecting fuel into an intake passage or a combustion chamber is provided for each cylinder.

[0003]

However, in a small boat that shifts from the non-skid state to the skid state when the engine speed exceeds the skid start engine speed, the engine speed is higher than the skid start engine speed that requires a high engine output. Also in the range, fuel is injected only from a single fuel injection valve for each cylinder, so that the fuel injection amount at each fuel injection valve is larger than the required fuel injection amount.

Since the fuel injection amount of the fuel injection valve is controlled by the injection time, the fuel injection time becomes longer in an engine rotation speed region equal to or higher than the engine rotation speed at which the fuel injection amount is increased. In a direct injection engine that directly injects fuel into a combustion chamber from a valve, the amount of fuel blow-through from an exhaust port is increased, and the engine output is reduced.

[0005] Further, in the idling state before the start of the run, the required fuel injection amount is small, so that the fuel injection time at the fuel injection valve is shortened, and the variation of the fuel injection amount is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to minimize the flow of fuel from an exhaust port so as to reliably maintain a sliding state, and to improve the condition before starting the sliding. It is an object of the present invention to provide a fuel injection engine capable of minimizing the variation in the fuel injection amount at the time of the above and allowing the small boat to smoothly shift to the sliding state.

[0007]

In order to achieve the above object, the invention according to claim 1 is directed to a fuel mounted on a small boat that shifts from a non-skid state to a skid state when the engine speed exceeds the skid start engine speed. In an injection engine, a first fuel injection valve injects fuel over substantially the entire engine speed range, and a second fuel injection valve injects fuel in at least a part of an engine speed range that is substantially equal to or higher than the engine speed at which the skid starts. Is provided for each cylinder. Here, the fuel is injected from the second fuel injection valve over a part of the engine speed range, as well as when the fuel is injected from the second fuel injection valve over the entire engine speed range equal to or higher than the sliding start engine speed. Is also included. In short, in the engine speed range substantially equal to or lower than the engine start speed, the fuel injected from the first fuel injector covers almost all the fuel required for combustion, and the engine speed range substantially equal to or higher than the engine start speed. In at least a part of the above, the fuel injected from both the first fuel injection valve and the second fuel injection valve may cover the amount of fuel required for combustion.

According to a second aspect of the present invention, in the first aspect of the present invention, the second fuel injection valve has a small amount of fuel that is not used for combustion in an engine speed range equal to or lower than a sliding start engine speed. Is characterized by being injected.

Therefore, according to the first aspect of the present invention, the fuel is injected from both the first and second fuel injection valves in the engine speed range equal to or higher than the engine speed at which the sliding starts. The fuel injection amount of each fuel injection valve with respect to the amount may be small, and in particular, the fuel injection time of the first fuel injection valve is shortened, so that fuel blow-through from the exhaust port can be minimized and fuel efficiency can be improved. At the same time, the sliding state can be reliably maintained. In addition, since the fuel injection time of the first fuel injection valve can be set to be long before the start of the run, the variation in the fuel injection amount can be kept small, and the small boat can be smoothly shifted to the run state.

According to the second aspect of the present invention, a small amount of fuel is injected from the second fuel injection valve so as not to be used for combustion even before the start of the run, so that the second fuel injection valve is cooled by the fuel. Its durability is increased.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a side view of the personal watercraft, FIG. 2 is a sectional view of the engine of the personal watercraft viewed from the rear, and FIG. 3 is a cutaway plan view of a fuel injection engine according to the present invention.

A fuel injection type engine 3 according to the present invention is mounted at a substantially central portion of the hull 2 of the watercraft 1 shown in FIG. 1 in the front-rear direction, and a fuel tank 4 is provided in front of the engine 3. Have been. The upper portion of the fuel tank 4 of the hull 2 is covered by a cowling 5, and a steering handle 6 is provided diagonally outside the cowling 5 above the fuel tank 4, and a seat 7 is provided behind the steering handle 6. Are detachably provided. The hull 2 is constituted by connecting a hull 2a made of FRP (fiber reinforced plastic) and a deck 2b with a gunnel 2c, and the inside of the hull 2 is communicated with the atmosphere through front and rear air ducts 8 and 9.

The fuel injection engine 3 according to the present invention is a water-cooled two-cycle two-cylinder engine 3,
As shown in FIGS. 2 and 3, two cylinders 3 b are arranged in the cylinder body 3 a in the front-rear direction, and the engine 3 is elastically supported on the bottom in the hull 2 via a plurality of engine mounts 10. The crankshaft 11 is arranged in the longitudinal direction of the hull 2.

As shown in FIG. 2, a piston 12 is fitted to each cylinder 3b of the engine 3 so as to be slidable up and down, and each piston 12 is connected to a crank web of the crank shaft 11 via a connecting rod 13. 11a.

A combustion chamber S is formed for each cylinder in the cylinder head 14 attached to the upper surface of the cylinder body 3a. An ignition plug 15 facing the chamber S is screwed substantially vertically, and a first fuel injection valve (injector) 16 opening to each combustion chamber S is screwed obliquely beside each ignition plug 15. Then, on the intake side of the cylinder body 3a (on the right side in the traveling direction indicated by the arrow F in FIG. 3,
A second fuel injection valve (injector) 17 that opens to the cylinder 3b of each cylinder is screwed substantially horizontally on the left side in FIG. 3). Therefore, in the fuel injection engine 3 according to the present embodiment, two first and second fuel injection valves 16 and 17 are attached to each cylinder.

By the way, as shown in FIG.
And a delivery pipe 18 for the second fuel injection valves 16 and 17.
Although fuel Kara predetermined pressure (5 kg / cm ² or so) is supplied, it is the delivery pipe 18 fed from the fuel tank 4 the fuel supply pipe 19 fuel (see FIG. 1) by a fuel pump (not shown), Excess fuel not injected in each of the fuel injection valves 16 and 17 is returned to the fuel tank 4 through the fuel return pipe 20. Note that lubricating oil is supplied in the middle of the fuel supply pipe 19. Also, the fuel return pipe 20
Is provided with a pressure regulator 21 for controlling the fuel injection pressure.

On the other hand, an intake pipe 22 is connected for each cylinder to the intake system on the right side of the fuel injection type engine 3 (on the right side in the traveling direction, and in the upper side in FIG. 3).
A common intake silencer 23 is connected to the intake pipes 22, and a reed valve 24 is provided at a portion of the crankcase 3c where each intake pipe 22 is connected to allow only fresh air to flow in the direction of the crank chamber. Have been. In addition, each intake pipe 2
A throttle valve (not shown) is accommodated in 2.

In the exhaust system on the left side of the cylinder body 3a of the engine 3, exhaust ports (not shown) of the respective cylinders are opened at equal intervals in the front-rear direction. An exhaust manifold 25 is connected to these exhaust ports. ing. The exhaust manifold 25 extends upward and then rises upward. An exhaust pipe 26 is connected to an end of the exhaust manifold 25.

The exhaust pipe 26 extends substantially horizontally toward the rear of the engine 3 and then bends downward to extend substantially horizontally rearward. The end of the exhaust pipe 26 is disposed at the rear of the engine 3. 27 is connected to the front. An exhaust pipe 28 extends upward from the rear upper surface of the water lock 27. The exhaust pipe 28 extends rearward of the hull 2 and has a rear end opening into water.

On the other hand, as shown in FIG. 1, a propulsion unit 30 is provided at a rear portion of the hull 2, and the propulsion unit 30 has a housing 31 that opens to the bottom and rear of the hull. Inside the crankshaft 1
An impeller shaft 32 arranged coaxially with 1 faces. The impeller shaft 32 is connected to the crankshaft 11 by a coupling 33, and an impeller 34 housed in the housing 31 is connected to a rear end of the impeller shaft 32.

The rear end of the housing 31 is open rearward, and the opening is provided with a deflector 3.
5 is attached to be able to swing right and left. The deflector 35 is linked to the steering handle 6 via an operation cable (not shown), and the watercraft 1 is steered by changing the direction of the deflector 35 by the steering operation of the steering handle 6. .

Next, the operation of the watercraft 1 according to the present embodiment will be outlined.

When the fuel injection engine 3 is driven in the watercraft 1, the rotation of the crankshaft 11 is transmitted to the impeller shaft 32 via the coupling 33, and is connected to the impeller shaft 32. The impeller 34 is integrally rotated at a predetermined speed.

When the impeller 34 is driven to rotate as described above, the impeller 34 raises the pressure of the water sucked from the bottom opening in the housing 31 and injects the water backward from the deflector 35. Therefore, the required thrust is generated by this water injection, but the thrust generated by the rotation of the impeller 34 is small while the engine speed does not reach the start engine speed, and the watercraft 1 separates the water. So-called displacement-type sailing.

After that, when the engine speed increases and the hull speed increases, the hull resistance that the hull 2 receives from the water surface increases accordingly. Transition to the state.

When the engine speed further increases, the bow of the personal watercraft 1 lowers, and the personal watercraft 1 performs a planing type sailing so as to slide on the water surface.

Here, the sliding state includes both the transition state and the sliding type running state, and the non-sliding state refers to a displacement type running state. Then, the engine speed at the time of transition to the transition state which is a part of the gliding state is the gliding start speed.

Next, the fuel injection control in the fuel injection type engine 3 according to the present invention will be described with reference to FIGS. FIG. 4 shows the fuel injection time of the first and second fuel injection valves and the change over time of the engine speed and the throttle opening, and FIGS. 5, 6, and 7 show the time at low speed, at high speed, and at high speed, respectively. It is a figure which shows the fuel injection timing at the time of acceleration, and a fuel injection time with respect to a crank angle.

The fuel injection type engine 3 according to the present embodiment
The fuel injection pressure in each of the first and second fuel injection valves 16 and 17 is maintained substantially constant by the pressure regulator 21 (see FIG. 3). Is controlled by the fuel injection time (period).

When the throttle opening increases after the start of the engine 3 as shown in FIG. 4, the engine speed also increases as shown in FIG. The gliding start engine speed, which is the engine speed when the boat 1 transitions to the transition state, is about 2000
rpm, and a gliding type cruise starts at about 3000 rpm.

Each of the first fuel injection valves 16 supplies fuel over substantially the entire engine speed range to the combustion chamber S of each cylinder (see FIG. 2).
On the other hand, the second fuel injection valve 17 supplies a small amount of fuel that is not used for combustion in an engine rotation speed range including the idling and substantially less than the engine rotation speed (2000 rpm) at which the engine starts sliding (see FIG. 2). Spray
A predetermined amount of fuel is injected into each of the cylinders 3b in an engine speed range substantially equal to or higher than the engine rotation speed at which the gliding starts (specifically, an engine speed range equal to or higher than the engine speed (3000 rpm) at which the gliding type sailing starts). That is, in the engine speed range substantially equal to or lower than the engine start speed, the fuel injected from the first fuel injection valve 16 covers substantially all of the fuel required for combustion, and the engine speed substantially equal to or higher than the engine start speed. In at least a part of the range, the fuel injected from both the first fuel injection valve 16 and the second fuel injection valve 17 covers the required fuel amount. In the engine speed range equal to or higher than the engine speed at which the skid starts, both the fuel injection amounts (fuel injection times) from the first and second fuel injection valves 16 and 17 increase as the engine speed increases.

Here, the fuel injection timing and the fuel injection time (fuel injection amount) at the time of low rotation when the engine rotation speed is less than the engine rotation speed at the start of sliding will be described with reference to FIG.
5 to 7, TDC is top dead center, BDC is bottom dead center, Eo is an exhaust port open, Ec is an exhaust port closed, Sc
o indicates the scavenging port open, and Sc indicates the scavenging port closed.

In the two-cycle engine 3, when the piston 12 descends in the cylinder 3b and the exhaust port is opened by the piston 12, high temperature and high pressure combustion gas generated by the combustion of the air-fuel mixture in the previous cycle is exhausted. When the scavenging port is opened by further lowering the piston 12 after being discharged from the port, fresh air that has been primarily compressed in the crank chamber flows into the cylinder 3b from the scavenging port.

At the time of low rotation, as shown in FIG. 5, after the scavenging port is opened, the piston 12 reaches the vicinity of the bottom dead center (BDC) (about 200 ° before the top dead center of the crank angle). , Fuel injection from the first fuel injection valve 16 into the combustion chamber S is started, and this fuel injection is performed until the exhaust port is closed (about 80 ° before the top dead center of the crank angle). still,
In this case, the fuel injection end time is delayed as the engine speed increases, so that the fuel injection time (ie, the fuel injection amount) increases.

The fuel injected into the combustion chamber S is mixed with fresh air flowing from the scavenging port to form an air-fuel mixture having a predetermined air-fuel ratio. 3b, and is ignited and burned by the spark plug 15 (see FIGS. 2 and 3) immediately before the piston 12 reaches the top dead center (TDC).

As described above, at the time of the low rotation before the start of the sliding, each combustion chamber S
The fuel is injected into the first fuel injection valve 16 so that the fuel injection time at the first fuel injection valve 16 can be set longer than the required fuel injection amount at the time of low rotation. As a result, the variation in the fuel injection amount can be reduced. Thus, the watercraft 1 can be smoothly shifted to the planing state.

By the way, as described above, even when the engine is running at a low speed less than the engine rotation speed at which the sliding starts, a small amount of fuel that cannot be used for combustion from the second fuel injection valve 17 is supplied to each cylinder 3b.
Is injected into the second fuel injection valve 17 by the fuel.
Is cooled and the sliding surface between the piston 12 and the cylinder 3b is effectively lubricated by the lubricating oil contained in the fuel. If the second fuel injection valve 17 is arranged upstream of the throttle valve of the intake pipe 22 and a small amount of fuel is injected from this, the lubricating oil contained in the fuel will lubricate the throttle valve and the reed valve 24 (not shown). Are ensured to ensure these smooth operations.

Next, the fuel injection timing and the fuel injection time (fuel injection amount) at the time of high rotation when the engine speed is equal to or more than the engine speed at which the gliding starts will be described with reference to FIG.

When the engine speed is higher than the sliding start engine speed at high engine speed, first, after the exhaust port is opened and before the scavenging port is opened as shown in FIG. The injection of fuel into the combustion chamber S is started, and subsequently the cylinder 3 of each cylinder is supplied from the second fuel injection valve 17.
The injection of fuel into b is started. The fuel injection from the first fuel injection valve 16 to the combustion chamber S is performed until immediately before the exhaust port closes, and the fuel injection from the second fuel injection valve 17 to the cylinder 3b is performed.
Fuel injection continues until immediately after the exhaust port closes,
The fuel injected from the first and second fuel injection valves 16 and 17 is mixed with fresh air flowing into the cylinder 3b from the scavenging port to form an air-fuel mixture having a predetermined air-fuel ratio. Similarly, after the exhaust port is closed by the piston 12, it is compressed in the cylinder 3b and the piston 1
2 is ignited and burned by the spark plug 15 immediately before reaching the top dead center (TDC).

The fuel injection timings from the first and second fuel injection valves 16 and 17 immediately after the engine speed exceeds the start of the run are near points a and b shown in FIG. The fuel injection start timing gradually advances, and the fuel injection time (that is, the fuel injection amount) increases.

Since the fuel is injected from both the first and second fuel injection valves 16 and 17 at the time of the high engine rotation speed equal to or higher than the engine rotation speed at which the sliding starts, each fuel injection valve with respect to the required fuel injection amount is provided. The fuel injection amount at the fuel injection valves 16 and 17 can be reduced. In particular, the fuel injection time of the first fuel injection valve 16 can be shortened to minimize fuel blow-through from the exhaust port, thereby improving fuel efficiency. It is possible to reliably maintain the watercraft 1 in the running state.

Here, the fuel injection timing and fuel injection time (fuel injection amount) during acceleration are shown in FIG. 7. During acceleration, the fuel injection from the first and second fuel injection valves 16 and 17 is advanced. The fuel injection is started immediately before the exhaust port is opened, and the fuel injection from both the fuel injection valves 16 and 17 is terminated immediately after the scavenging port is closed and immediately before the exhaust port is closed.

The above description has been made of the embodiment in which the present invention is applied to a fuel-injection type water-cooled two-cycle two-cylinder engine mounted on a watercraft, in particular. It is needless to say that the present invention is similarly applicable to a fuel injection type engine.

[0045]

As is apparent from the above description, claim 1
According to the invention described above, fuel is injected from both the first and second fuel injection valves in an engine rotation speed range equal to or higher than the engine rotation speed at which the sliding starts. A small fuel injection amount is required, and in particular, the fuel injection time of the first fuel injection valve is shortened to minimize fuel blow-through from the exhaust port, thereby improving fuel efficiency and reliably maintaining a sliding state. can do. Further, since the fuel injection time of the first fuel injection valve can be set long before the start of the gliding, the effect that the variation in the fuel injection amount can be suppressed small and the small boat can be smoothly shifted to the gliding state. can get.

According to the second aspect of the present invention, a small amount of fuel that is not used for combustion even before the start of skiing is injected from the second fuel injection valve, so that the second fuel injection valve is cooled by the fuel. Its durability is increased.

[Brief description of the drawings]

FIG. 1 is a side view of a watercraft.

FIG. 2 is a sectional view of an engine portion of the watercraft as viewed from the rear.

FIG. 3 is a cutaway plan view of the fuel injection engine according to the present invention.

FIG. 4 is a first view of the fuel injection engine according to the present invention;
FIG. 6 is a diagram showing changes over time of a fuel injection time of a second fuel injection valve, an engine speed, and a throttle opening.

FIG. 5 is a view showing a fuel injection timing and a fuel injection time at a low rotation speed of the fuel injection engine according to the present invention with respect to a crank angle.

FIG. 6 is a diagram showing a fuel injection timing and a fuel injection time with respect to a crank angle at the time of high rotation of the fuel injection engine according to the present invention.

FIG. 7 is a diagram showing a fuel injection timing and a fuel injection time at the time of acceleration of the fuel injection engine according to the present invention with respect to a crank angle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Watercraft (small boat) 3 Fuel injection type engine 16 1st fuel injection valve 17 2nd fuel injection valve

Claims (2)

[Claims] 1. A fuel injection engine mounted on a small boat that shifts from a non-skid state to a skid state when the engine speed exceeds a skid start engine speed, wherein a first fuel is injected over substantially the entire engine speed range.
A fuel injection engine comprising: a fuel injection valve; and a second fuel injection valve for injecting fuel in at least a part of an engine speed range substantially equal to or higher than a sliding start engine speed for each cylinder. 2. The fuel injection type fuel injection system according to claim 1, wherein the second fuel injection valve injects a small amount of fuel that is not used for combustion in an engine speed range equal to or lower than a sliding start engine speed. engine.