JPH10252564A - Parallel multi-cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make possible arranging of a plurality of carburetors, additionally provided in a parallel multi-cylinder engine, by narrowing a width in a parallel direction of a cylinder, so that the engine can be formed into compactness by narrowing a space between the cylinders, and also a degree of freedom arranging accessories, operated in accordance with turn rolling of a throttle shaft, is enhanced. SOLUTION: In a parallel multi-cylinder engine provided with a plurality of carburetors, the carburetors 36 connected to each cylinder are arranged in parallel to a parallel direction of the cylinder, and also each carburetor 36 is provided in a direction its throttle shaft 80 is extended in a direction almost orthogonal to the parallel direction of the cylinder. In this way, a space for connecting in series the fellow throttle shafts 80 is omitted, these carburetors 36 can be arranged by narrowing a width of the space in the parallel direction of the cylinder, since an end part of each throttle shaft 80 is independent of each other, these throttle shafts can be utilized as a location arranging accessories of throttle sensor 92, pressure pump 90, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel multi-cylinder engine in which a plurality of cylinders are arranged in parallel with a crankshaft, and more particularly, to an arrangement structure of a carburetor provided for each cylinder.

[0002]

2. Description of the Related Art There are various types of engines used as power sources for vehicles, ships, and the like. One type is a parallel multi-cylinder having a structure in which a plurality of cylinders are arranged in parallel with a crankshaft. There is an engine. In such a parallel multi-cylinder engine, a carburetor system is provided for each cylinder to supply an air-fuel mixture from the carburetor to each cylinder for the purpose of achieving an intended engine output. Is adopted.

That is, in the conventional multiple carburetor system, the carburetors connected to the cylinders are arranged in such a direction that their throttle shafts extend in a direction parallel to the parallel direction of the cylinders. All the throttle shafts are arranged on the same line by being arranged in parallel with the parallel direction, and these throttle shafts are connected at their ends. Therefore, by connecting the throttle shafts to each other between the carburetors, the throttle shafts rotate integrally based on the throttle operation, and the throttle valve openings of the carburetors are changed synchronously. I have. The throttle shafts are connected to each other with a detachable connecting member interposed therebetween. If there is a deviation in the throttle valve opening between the carburetors, the connecting members are loosened to reduce the rotational angle relationship between the throttle shafts. Can be adjusted and adjusted to the proper state.

[0004]

However, when connecting the throttle shafts of the carburetors arranged on the same line, the ends of the throttle shafts projecting from the carburetor body to the outside are connected. As the number of carburetors to be connected increases, the protrusion amount of the throttle shaft is added, and the carburetor unit composed of the plurality of carburetors becomes wider in the parallel direction of the cylinders. This situation is exacerbated by the fact that a connecting member must be interposed between the ends of the throttle shaft for adjusting the throttle valve opening.

However, since the size of an engine room for mounting a parallel multi-cylinder engine in a vehicle or a ship is limited, the interval between the cylinders is made as small as possible, and the engine is vaporized accordingly. It is also required that the cylinder unit has a narrow width in the parallel direction of the cylinders. Particularly, as described in JP-A-62-59194 and JP-A-5-246385, a boat in which an occupant straddles over a hull and propells the hull by the driving force of an engine housed in the hull. In order to exhibit the inherent kinetic performance of a boat, it is required that a power unit including a parallel multi-cylinder engine, a carburetor unit, and the like be compact and housed in a hull.

[0006] The carburetor unit includes various types of components such as a throttle sensor for detecting the throttle opening from the rotation angle of the throttle shaft, an acceleration pump for increasing the amount of fuel supplied to the carburetor according to the rotation of the throttle shaft, and the like. An accessory is provided, and such an accessory is usually provided at the end of the throttle shaft in order to obtain rotational movement of the throttle shaft.

However, in the conventional multiple carburettor structure, since the throttle shafts of the carburetors are connected in a straight line, the parts where the above-mentioned auxiliary equipment can be disposed are located at both ends of the carburetor unit. This was a major obstacle in designing the power unit. Furthermore, when the auxiliary units are disposed at both ends of the carburetor unit as described above, when the power unit is stored in the engine room, these auxiliary units are disposed at a relatively deep position in the engine room. As a result, only a limited space for maintenance work can be obtained,
There has been a problem that it is difficult to make necessary adjustments and the like to these auxiliary machines.

The present invention has been made in view of the above-mentioned conventional circumstances, and enables a carburetor unit attached to a parallel multi-cylinder engine to have a structure in which the width of a cylinder in a parallel direction is narrowed. It is an object of the present invention to make an engine compact by narrowing the interval between cylinders, and to increase the degree of freedom in arranging an auxiliary device that operates according to the rotation of a throttle shaft.

[0009]

In the parallel multi-cylinder engine according to the present invention, a plurality of carburetors connected to each cylinder are arranged in parallel with the parallel direction of the cylinders, and each carburetor is connected to its throttle shaft (rotating shaft). The support shaft is provided in a direction extending in a direction substantially perpendicular to the direction in which the cylinders are arranged in parallel. That is, unlike the conventional multiple carburetor structure, the throttle shafts of the carburetors are connected in a straight line in parallel with the parallel direction of the cylinders and are arranged in series. The shafts independently extend in a direction substantially orthogonal to the direction in which the cylinders are arranged in parallel, and are arranged in parallel with each other.

For this reason, the space for connecting the throttle shafts in series is omitted, and the carburetors can be arranged with a reduced interval between the cylinders in the parallel direction. In addition, since the ends of the throttle shafts are independent of each other, they can be used as parts for arranging accessories such as a throttle sensor, and these accessories are provided on the side of the engine to perform maintenance work. Can be easily performed.

[0011] In the parallel multi-cylinder engine of the present invention,
The axis of the part where the throttle shaft of the carburetor is located in the part of each intake passage communicating with each cylinder,
It is formed substantially parallel to the cylinder axis of the cylinder. That is, the barrel passage portion of the carburetor is disposed substantially parallel to the cylinder axis. Further, in the parallel multi-cylinder engine of the present invention, the axis of the portion where the throttle shaft of the carburetor is located in the portion of each intake passage communicating with each cylinder is formed so as to be substantially orthogonal to the cylinder axis of the cylinder. ing. That is, a substantially barrel passage portion of the vaporizer extends in a direction substantially perpendicular to the cylinder axis.

As described above, the intake passage can be arranged in various modes. In the former case, the throttle shaft extends in a direction substantially perpendicular to the direction in which the cylinders are arranged in parallel, and extends in parallel with the cylinder axis of the cylinder. In the latter case, the throttle shaft extends in a direction substantially perpendicular to the parallel direction of the cylinders and extends in a direction substantially perpendicular to the cylinder axis of the cylinder. Is done. That is, the end portion of the throttle shaft, in which the intake passage system and the auxiliary equipment can be arranged, can be arranged in various positions and directions according to the layout requirements in the engine room.

Preferably, in a small boat, the parallel multi-cylinder engine of the present invention is mounted such that the parallel direction of the cylinders substantially coincides with the hull advancing direction. The throttle shaft of the carburetor is provided to extend in a direction substantially perpendicular to the direction in which the cylinders are arranged. In addition, in the parallel multi-cylinder engine of the present invention, in addition to forming an intake passage communicating with each cylinder with a plurality of intake manifolds connected to several cylinders divided into a plurality of cylinders, an independent intake passage is provided for each cylinder. It can be formed by an intake pipe.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A parallel multi-cylinder engine according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a three-cylinder 2 mounted on a saddle-ride type jet propulsion boat
This will be described using a cycle engine as an example. FIG. 1 shows a saddle-ride type jet propulsion boat according to the present embodiment, with a part thereof cut away, and FIG. 2 shows a cross-sectional structure taken along line AA of FIG.

As shown in the figure, a hull 1 is provided with a steering wheel 2 at a substantially central portion thereof, and a saddle-shaped seat portion 3 is provided at a rear portion of the steering wheel 2. In other words, the occupant sits on the seat 3 (the occupant is placed on the step 7 as shown in FIG. 2), and the jet propulsion is performed by operating the steering wheel 2. Steer the boat. Hull 1 is reinforced plastic (FRP)
The lower hull panel 4 and the upper hull panel 5 formed from the same are joined together from above and below.
Is formed in the buoyancy body structure. A portion of the upper hull panel 5 corresponding to the side of the seat portion 3 is formed in a step portion 7, and a portion of the space 6 below the step portion 7 is filled with a buoyant float 8.

A power unit including an engine 9 and the like are accommodated in a space 6 in the hull 1 and arranged with a center of gravity of the hull for obtaining a good steering feeling and an arrangement with a jet propulsion device 10 provided at the rear end of the hull. For reasons such as the relationship, the engine 9 is disposed in a relatively narrow space 6 formed below the seat portion 3. The jet propulsion device 10 forms a flow path from an intake port 11 opened at the bottom of the ship to a jet nozzle 12 opened at the rear end of the hull, and rotatably accommodates an impeller 13 in the flow path. Drive shaft 14
Is connected to the output shaft 15 of the engine 9 via the. In FIG. 1, reference numeral 16 denotes a seal member that rotatably supports the drive shaft 14 with watertightness. Therefore, when the impeller 13 is rotationally driven by the engine 9, the water taken in from the water intake 11 is jetted vigorously from the jet nozzle 12, whereby the hull 1 is propelled forward.

The engine 9 is a two-cycle engine in which three cylinders are arranged in parallel with the crankshaft.
The cylinder axis of each cylinder is disposed in the space 6 having a substantially inverted conical cross section formed at the lower portion of the cylinder so as to be directed to the top of the inverted conical shape at the center of the ship bottom. That is, since the parallel direction of the cylinders of the parallel multi-cylinder engine substantially matches the central axis of the hull (that is, the traveling direction of the hull), the hull is prevented from swinging left and right due to the piston motion of each cylinder. ,
Particularly in a ship traveling on water, a stable state in which roll vibration is suppressed is achieved. As shown in detail in FIGS. 3 and 4, in the engine 9, the cylinder block 24 and the cylinder head 25 are sequentially overlapped and integrally joined above the crankcase 23, and the crankcase 23 is attached to the engine hanger 26, The engine hanger 26 is attached to the hull 1 by attaching the engine hanger 26 to a boss 28 formed on the lower hull panel 4 via a mounting block 27.

Each of the three cylinder holes 29 formed in the cylinder block 24 of the engine 9 has a piston 30
Are slidably fitted, and each piston 30 is connected to a crankshaft 31 via a connecting rod 32. Therefore, the crankshaft 31 is driven to rotate as the piston 30 moves up and down, and this rotation driving force is output from the output shaft 15 to rotate the impeller 13.

One side of the cylinder block 24 (FIG. 2)
Intake ports 33 are provided for the respective cylinders (left side in the middle), and a reed valve 34 is provided in each of the intake ports 33. A carburetor 36 is connected to each intake port 33 via an intake pipe 35, and an air cleaner 37 is connected upstream of the carburetor 36. The vaporizer 36 has a fuel tank 38
Is supplied. Therefore, the throttle valve opening of the carburetor 36 is adjusted by operating a throttle lever (not shown) attached to the steering handle 2, and the fuel from the carburetor 36 is mixed with the air from the air cleaner 37. The air-fuel mixture is supplied to the crankcase 2 via a reed valve 34 and an intake pipe 35.
3.

The other side surface of the cylinder block 24 (FIG. 2)
Exhaust ports 39 are provided corresponding to the respective cylinders (in the right side inside), and exhaust control valves 40 are provided in the exhaust ports 39, respectively. These exhaust control valves 40 are swingably provided near an exhaust opening facing the cylinder hole 29, and are swingably driven in accordance with a boat speed by a cylinder device described later. That is, the exhaust control valve 40 controls the opening area of the exhaust port 39 so as to obtain an optimal exhaust opening ratio according to the operating condition of the bottom of the ship.
During low-load operation, the exhaust port 39 is closed to perform active hot atmosphere combustion, thereby improving fuel efficiency and purifying exhaust gas.

The active hot atmosphere combustion is also called AR combustion. For example, as described in JP-A-7-71279 and JP-A-7-180556, an inner wall of an exhaust passage near the upper edge of an exhaust port is disclosed. An exhaust control valve that opens and closes the exhaust port is provided. During low-speed, low-load operation of the two-stroke engine, the exhaust control valve closes the exhaust port almost completely, so that the cylinder pressure is properly controlled and The heat energy of the remaining burned gas activates fresh air in the combustion chamber to cause self-ignition combustion, thereby improving engine fuel efficiency and purifying exhaust gas.

Each exhaust port 39 is connected to an exhaust manifold 41, and is collectively connected to an exhaust chamber 42 via the exhaust manifold 41. Further, the exhaust chamber 42 is connected to a silencer (not shown) provided at the rear end of the hull, and the exhaust from the exhaust port 39 is supplied to the exhaust port 41 via the exhaust manifold 41, the exhaust chamber 42, and the silencer. From the hull 1 to the outside. In this embodiment, the exhaust manifold 4
1 opens toward the front side (left side in FIG. 1) of the hull 1
The exhaust chamber 42 has a tip connected to this opening.
The exhaust chamber 42 is bent upward, extends rearward, and is connected to a silencer.

As shown in FIG. 4, the exhaust control valve 40 has a shape in which the ends of a pair of substantially fan-shaped plate portions 43 are connected by a valve plate portion 44 having an arc-shaped cross section. It is accommodated in a concave portion 45 having a circular arc shape in vertical section formed on the upper edge portion of the exhaust port. An exhaust control valve support bracket 46 is interposed and fixed between the cylinder block 24 and the exhaust manifold 41, and a through hole 47 is formed in the support bracket 46 to allow each exhaust port 39 to communicate with the exhaust manifold 41. ing. Support bracket 4
6 rotatably supports a pivot 48 extending between the cylinders. The pivot 48 has a plate-like portion 4 of each exhaust control valve.
One base end is fixedly attached by a screw 49.
Therefore, by rotating the pivot 48, which supports each of the exhaust control valves 40 in common, about the axis thereof, the exhaust control valves 40 are opened and closed, and the opening ratio of the exhaust port 39 is set between substantially fully closed and fully open. Can be changed.

Incidentally, as shown in FIG.
The exhaust passage extending from the exhaust manifold 41 is bent downward toward the exhaust manifold 41 so as to bypass the upper edge of the exhaust port 39, so that the pivotal axis extends in the direction crossing the extending direction of the exhaust port 39 as described above. 48 can be provided. As a result, the pivot 48 can be shared, and the support structure of the exhaust control valve 40 is simplified, so that the assembling work of the engine 9 is facilitated. As shown in FIG. 4, a water jacket 50 for flowing cooling water is formed in the exhaust manifold 41, and a water jacket for communicating cooling water to the cylinder block 24 via the pipe 51 to the water jacket 50. A jacket 52 is formed.

Further, five scavenging ports 53 are formed in the upper part of each cylinder hole 29, and each of the scavenging ports 53 communicates with the inside of the crankcase 23 through a scavenging passage 54 penetrating the cylinder block 24 in the vertical direction. ing. Therefore, the scavenging operation in the two-stroke engine is performed in which the air-fuel mixture supplied into the crankcase 23 is compressed by the lowering of the piston 30, and is pressure-fed to the combustion chamber in the cylinder via the scavenging passage 54 and the scavenging port 53. .

As shown in FIG.
A cylinder device 55 is attached to the outer wall of
The piston rod 56 of the cylinder device 55 is connected at its tip to the pivot 48 of the exhaust control valve. The cylinder device 55 slidably accommodates a piston 59 in a cylinder body 57 via a diaphragm.
9 shows a piston rod 56 projecting from the cylinder body 57.
Is attached.

The cylinder 5 has a piston 5
Inflow port 6 for supplying fluid to the pressure chamber facing the pressure receiving surface 9
1 and an outflow port 62 for discharging the fluid from the pressure chamber, and a return spring 63 for constantly biasing the piston 59 in a direction against the water pressure from the pressure chamber is provided. Therefore, when a certain level of water pressure is applied to the pressure chamber, the piston 59 returns to the return spring 6.
When the water pressure decreases below a certain level, the piston rod 56 is retracted by the return force of the return spring 63. The tip of the piston rod 56 is connected to a lever 66 attached to the end of the pivot 48,
The movement of the piston rod 56 causes the pivot 48 to rotate together with the lever 64. That is, when the piston rod 56 protrudes due to a certain level of water pressure applied to the pressure chamber, the lever 66 rotates and the exhaust control valve 40
Makes the exhaust port 39 an opening ratio of 100%, while when the water pressure decreases below a certain level and the piston rod 56 retracts, the lever 66 rotates in the opposite direction and the exhaust control valve 40 closes the exhaust port 39. It is almost fully closed.

Here, in the present embodiment, the cylinder device 5
The water flow pressurized by the jet propeller 10 is supplied to the pressure chamber 5 and the exhaust control valve 40 is driven in the opening direction by the rotation speed of the impeller 13 and the pressure of the water flow rising. 100% exhaust port 39
Aperture ratio. That is, when the rotation speed of the impeller 13 is not very high (that is, in the low-speed / low-load operation state), the pressure of the water flow guided to the pressure chamber does not become too high, and the exhaust control is performed by the urging force of the return spring 63. The valve 40 is driven in the closing direction, and the exhaust port 39 is almost fully closed to bring about AR combustion.

As shown in detail in FIG. 3, the engine 9 of this embodiment is a two-stroke engine of a separate oil supply system, and an oil pump 70 is provided at the tip of a crankshaft 31. The cylinder block 2 is driven by the rotation of the crankshaft 31.
The lubricating oil tank 7 via an oil passage 71 provided in
The lubricating oil is fed under pressure from 2 to various parts of the engine 9.
2 is an oil lid for replenishing the lubricating oil tank 71 with lubricating oil, and 74 in FIG. 1 is a fuel lid for replenishing the fuel tank 38 with fuel. Reference numeral 75 shown in FIGS. 1 and 3 is an ignition plug provided for each cylinder, and ignites compressed air in the combustion chamber.

A total of three carburetors 36 are provided for each cylinder. As shown in FIG.
These carburetors 36 are arranged in parallel with the parallel direction of the cylinders. Further, as shown in FIG. 5 showing the structure as viewed in the direction of arrow B in FIG. 4 and FIG. 6 showing the structure as viewed in the direction of arrow C in FIG.
Are arranged so that their throttle shafts 80 extend in a direction substantially orthogonal to the parallel direction of the cylinders, and the throttle shafts 80 of the respective carburetors are independently arranged in parallel with each other. Numerals 36 are integral carburetor units arranged at a relatively small distance from each other and fixed to each other by stays 79. Here, in the present embodiment, as shown in FIG. 2, an intake passage system from the air cleaner 37 to the intake port 33 is disposed vertically in a downward direction, and a throttle shaft 80 of the intake passage system is located. The part (barrel part of the carburetor) is disposed substantially parallel to the cylinder axis of the cylinder. For this reason, the horizontal axis of the power unit can be suppressed, and the lateral width of the hull portion (that is, the engine room portion) over which the occupant straddles is suppressed, and the hull shape is easy for the occupant to board.

This situation is the same in a general vehicle or a non-saddle-type ship, and the width of the engine room can be reduced as required in designing the vehicle body and the hull. Sufficient maintenance space can be secured in the engine room. In the present invention, various aspects other than the above-described aspects can be adopted. For example, a portion where the throttle shaft 80 of the intake passage system is located is disposed in a direction substantially orthogonal to the cylinder axis of the cylinder. Then, the intake passage system can be extended to the side of the engine. In this case, the height of the power unit can be reduced in accordance with the shape of the engine room, and the power unit can be sufficiently provided in a limited engine room. Maintenance space can be secured.

As shown in FIG. 7, the throttle shaft 80 is rotatably supported by a carburetor body 81 with its end protruding to the outside.
A throttle valve 83 for adjusting the throttle opening is attached to a portion located inside the carburetor barrel 82. Further, a venturi is provided in the barrel 82 for ejecting and atomizing the fuel.

A lever 85 is attached to the tip of each throttle shaft 80, and adjacent levers 85 are connected to each other by a link 86.
A throttle wire (not shown) is connected to one of these levers 85 via a stop screw 87 for adjusting the tension of the wire. When pulled, each throttle shaft 80 is synchronously rotated and displaced via the lever 85 and the link 86. A return spring 88 is wound around each throttle shaft 80, and when no pulling force is applied from the throttle wire, such as during idling operation, the return spring 88 is used by the return spring 88.
Returns to the rotation position where the throttle opening is minimized.

At one end of the throttle shaft 80 opposite to the end connected by the link 86, one of the throttle shafts 80 is connected.
A cam 89 is attached to each of them, and an acceleration pump 9 attached to the carburetor body 81 is provided near the cam 89.
0 is provided. Piston rod 9 of acceleration pump 90
1 is in contact with each 89 at its tip, and when each 89 rotates together with the throttle shaft 80, the piston rod 9
When 1 is pushed in, the acceleration pump operates. That is, a certain amount of fuel is supplied into the acceleration pump 90, and when the throttle opening is rapidly opened at the time of engine start or rapid acceleration, the fuel is also supplied from the acceleration pump 90 to the venturi 84. The concentration of the air-fuel mixture generated by the vaporizer 36 is set to an optimum value.

A throttle sensor 92 is attached to one of the other throttle shafts 80 at the end opposite to the connection end by the link 86, and the throttle sensor 92 rotates the throttle shaft (rotation of the throttle shaft 92). That is, the throttle opening) is detected to control the operation of the engine. As described above, in the present invention, since the throttle shafts 80 of the respective carburetors are independently arranged in parallel with each other, it is easy to obtain a portion where the acceleration pump 90 and the throttle sensor 92 can be arranged. Can be. Further, these carburetors 36 are attached to the engine 9 and are accommodated in the relatively narrow space 6.
6, and auxiliary equipment such as an acceleration pump and a throttle sensor 92 are arranged on the side of the carburetor unit, so that maintenance work can be easily performed.

In this embodiment, as shown in FIGS. 6 and 7, lubricating oil is supplied to the bearing portion of the throttle shaft 80, and since the engine is a two-cycle engine, the lubricating oil is added to the air-fuel mixture. Adopt a structure to mix. That is, the throttle shaft 80 is attached to the flange portion 94 of the carburetor 36 joined to the intake pipe 35.
Are formed with a pair of oil holes 95 communicating with the respective bearing portions, and a dovetail groove 96 connecting the oil holes 95 is formed. A lubrication plug 97 is provided on a flange portion 93 of the intake pipe joined to the flange portion 94 of the vaporizer, and the vaporizer 36 is attached to the intake pipe 35 by joining these flange portions 93 and 94 in a liquid-tight manner. In this state, an oil path from the lubrication plug 97 to the two bearings of the throttle shaft 80 via the dovetail groove 96 and the oil hole 95 is defined. The throttle shaft 80
A peripheral groove 80a is formed at a position facing the oil hole 95 in the bearing portion of the throttle shaft 80, and contributes to supply of oil to the entire bearing portion of the throttle shaft 80.

Then, lubricating oil is supplied under pressure from the oil pump 70 to the lubrication plug 97 via a pipe (not shown), and this lubricating oil is forcibly supplied to both bearings of the throttle shaft 80 through the above oil passage. Is done. An oil seal 98 is provided at a position outside the oil holes 95 of the bearings, so that the oil lubricating the bearings drops into the barrel 82 without leaking to the outside. Especially in ships where bilge water may enter the engine room, the end of the throttle shaft must be exposed to the outside for mounting auxiliary equipment, etc. This is effective in preventing bilge water from entering the engine from the throttle shaft bearing.

The jet propulsion boat having the above-described structure is steered by an occupant sitting on the step portion 7 with the foot on the seat portion 3 and operating the steering wheel 2. And since the vaporizers are made compact units by narrowing the space between each other, the power unit housed in the space 6 of a limited size in the hull 1 can be made compact, and the jet propulsion boat is expected. Mobility etc. can be exhibited.

Here, in a normal operation state except at low speed and low load, the exhaust control valve 40 has the exhaust port 39 fully opened, and the exhaust port
The air-fuel mixture supplied into the cylinder 3 is supplied into the combustion chamber from the scavenging port 54 as the piston 30 descends, and the air-fuel mixture is compressed by the rise of the piston 30 to be ignited and burned by the spark plug 75, and the piston 30 descends again. A normal two-cycle process of exhausting burned gas from the exhaust port 39 and performing scavenging is repeated by the impeller 1.
3 is rotated at high speed. On the other hand, in the low-speed / low-load operation state in which the rotation speed of the impeller 13 is low or the rotation of the impeller 13 is stopped in the idling operation state, the exhaust control valve 40 closes the exhaust port 39 substantially. , Make the engine 9 keep the operation by AR combustion,
It improves fuel efficiency and purifies exhaust gas during low-load operation.

In the above-described embodiment, a saddle-ride type small boat is shown, but the present invention can be widely applied to a parallel multi-cylinder engine mounted on a vehicle or the like. Further, the present invention can be applied not only to a two-cycle engine but also to a four-cycle engine as long as it is a multiple carburetor type engine having a plurality of cylinders. is not. Further, in the above-described embodiment, the independent intake pipe 35 is provided for each cylinder, and the carburetor 36 is provided for each intake pipe 35. For example, two cylinders for four cylinders are collected by the intake manifold. Then, a multiple carburetor system in which a carburetor is provided for each intake manifold may be used.

[0041]

As described above, according to the present invention,
A carburetor attached to the parallel multi-cylinder engine and connected to each cylinder is arranged in parallel with the parallel direction of the cylinders, and each carburetor is oriented so that its throttle shaft extends in a direction substantially orthogonal to the parallel direction of the cylinders. Therefore, it is possible to easily obtain a portion where an auxiliary machine such as an acceleration pump is provided, increase the degree of freedom in design, and facilitate maintenance work of the auxiliary machine. Further, the interval between the carburetors can be reduced as compared with the conventional case, and the engine can be reduced in size by reducing the interval between the cylinders. As a result, the capacity of the engine room for mounting the engine can be reduced, and the original performance can be exhibited particularly in a small boat or the like that requires agile kinetic performance.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view showing a jet propulsion boat according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a longitudinal sectional view showing a two-cycle engine according to one embodiment of the present invention.

FIG. 4 is a plan view showing a two-stroke engine according to an embodiment of the present invention in a cross-sectional view along with an arrangement of a carburetor.

FIG. 5 shows a vaporizer according to one embodiment of the present invention as B in FIG.
It is a side view shown by an arrow.

FIG. 6 shows a carburetor according to an embodiment of the present invention.
It is a bottom view shown by arrow.

FIG. 7 is a longitudinal sectional view showing a vaporizer mounting structure according to an embodiment of the present invention.

[Explanation of symbols]

6 ... space (engine room), 9 ... engine, 35 ... intake pipe, 36 ... carburetor, 80
... Throttle shaft, 86 ... Link, 90
... Acceleration pump, 92 ... Throttle sensor,

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 9/02 361 F02D 9/02 361J 9/10 9/10 H F02M 17/34 F02M 17/34 D

Claims (5)

[Claims] In a parallel multi-cylinder engine provided with respective intake passages communicating with respective cylinders, a plurality of carburetors connected to the respective cylinders are arranged in parallel with the parallel direction of the cylinders, and provided in each carburetor. A parallel multi-cylinder engine, wherein a rotary shaft of a throttle valve for opening and closing the intake passage is arranged in a direction extending in a direction substantially perpendicular to a direction in which the cylinders are arranged in parallel. 2. The parallel multi-cylinder engine according to claim 1, wherein an axis of a portion of the intake passage where a throttle valve rotation support shaft of the carburetor is located is substantially parallel to a cylinder axis of the cylinder. Parallel multi-cylinder engine. 3. The parallel multi-cylinder engine according to claim 1, wherein an axis of a portion of the intake passage where a throttle valve rotation support shaft of the carburetor is located is substantially orthogonal to a cylinder axis of the cylinder. Parallel multi-cylinder engine. 4. A parallel multi-cylinder engine for small boats having respective intake passages communicating with respective cylinders, wherein the parallel multi-cylinder engine is mounted such that the parallel direction of the cylinders substantially matches the hull advancing direction, A plurality of carburetors connected to each cylinder are arranged in parallel with the parallel direction of the cylinders, and a rotation support shaft of a throttle valve that opens and closes an intake passage arranged substantially in parallel with the cylinder axis of the cylinder is aligned with the parallel direction of the cylinders. A parallel multi-cylinder engine characterized by being provided side by side in a direction extending substantially orthogonally. 5. The parallel multi-cylinder engine according to claim 1, wherein the intake passages are provided independently for each cylinder, and the carburetors are also provided for the respective intake passages. A parallel multi-cylinder engine characterized by being installed.