JPH01289791A - Intake device for on-vehicle longitudinal v type multiple cylinder engine - Google Patents

Abstract

PURPOSE:To enable a spatial margin to be formed behind an engine by laterally arranging the carburetor for the rear cylinder at the rear part of the rear cylinder, on the other hand, by laterally arranging the carburetor for the front cylinder in the neighborhood of the carburetor for the rear cylinder, and in the side view, by arranging it so as to overlap the rear cylinder. CONSTITUTION:When the titled intake device is applied to a longitudinal V type two-cylinder engine 1 (not shown) to be mounted on a snowmobile or the like, the front cylinder 2a on the far side to the sheave which has been fixed to the rear part of a crankshaft 3 is arranged in such a position as to be forwardly inclined nearly in the horizontal direction, while the rear cylinder 2b on the near side to the sheave is arranged in such a position as to be tilted slightly forward to the vertical direction. The respective cylinders 2a, 2b are connected to respective carburetors 15a, 15b having been connected to a common intake silencer, through separate intake air passages. Further, the respective carburetors 15a, 15b are laterally arranged, and the intake air passage 16a of the carburetor 16a is faced to the side surface of the rear cylinder 2b, and, in the side view, is arranged in such a positional relationship as to overlap the rear cylinder 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an intake system for a front and rear V-type multi-cylinder engine mounted on a vehicle such as a snowmobile.

[Prior art]

When installing a front and rear ■ type multi-cylinder engine in a vehicle such as a snowmobile, the multiple cylinders are distributed in the front and rear, so if a carburetor is connected to each cylinder, the carburetors are also distributed in the front and rear. As a result, the intake passage becomes complicated, and as a result, the intake resistance for each cylinder varies, resulting in variation in the output of each cylinder. Additionally, for this reason, it was sometimes necessary to install multiple stages of intake silencers and air cleaners for each cylinder.

To take such measures, in the case of a V-type multi-cylinder engine installed in a motorcycle, the opening of the intake passage of the front cylinder is closed to the intake passage of the rear cylinder, as disclosed in Japanese Patent Laid-Open No. 60-56123. It has been proposed that the carburetors are arranged side by side at the same position as the openings, and the carburetors are connected to each side in a front-to-back direction.

However, this device does not solve the problem of the overall length of the intake system from front to back, so it is necessary to move the engine mounting position further to the rear for stability, or to increase the volume of the air cleaner or intake silencer. It is not possible to obtain effects such as improving the intake noise muffling function. In addition, in the above device, the distance of the intake passage from the front cylinder's front-rank chamber entrance to the piston is longer than that of the rear cylinder, so this difference causes a difference in intake resistance, resulting in output variation between cylinders. It is unavoidable to do so.

[Purpose of the invention]

An object of the present invention is to make it possible to provide more space behind the engine when a front and rear type multi-cylinder engine is mounted on a vehicle as described above, thereby allowing the engine mounting position to be moved to the rear, Another object of the present invention is to provide an intake device that can increase the volume of an intake silencer or air cleaner, and that can prevent variations in output between cylinders.

[Structure of the invention]

In an intake system for a front and rear V-type multi-cylinder engine according to the present invention, which achieves the above object, among the front and rear V-type multi-cylinder engines, the carburetor of the rear cylinder is disposed laterally at the rear of the cylinder, while the carburetor of the front cylinder is disposed laterally at the rear of the cylinder. It is characterized in that it is disposed horizontally near the rear cylinder carburetor and overlaps with the rear cylinder in side view.

The present invention will be explained below with reference to embodiments shown in the figures.

FIG. 6 shows a snowmobile equipped with a front and rear type multi-cylinder engine according to the present invention. A running track 41 consisting of an endless strip is provided at the lower part of the rear half of the vehicle body, and is driven by a drive wheel 42 provided at the front end of the track 41 for running. Power is input to the drive wheels 42 from an engine, which will be described later, and the engine is connected to the shroud 4 that covers the front of the vehicle body.
It is located within 3. Further, steering skis 44, 44 are provided on the left and right sides of the lower part of the front part of the vehicle body, and are adapted to be steered by a handle 45 on the driver's seat. 46 is a sheet.

FIG. 1 shows the inside of the front part of the snowmobile,
2 to 5 show the engine in detail.

In these figures, 1 indicates two cylinders 2a forming a V-shape in the front and rear;
2b, and is placed horizontally so that its crankshaft 3 is in the width direction of the vehicle body. A sheave 4 is fixed to the end of the crank 3, and power is transmitted to the driving wheels 42 of the truck 41 described above through a belt 5 wound around the sheave 4. Reference numeral 49 denotes a steering shaft, the above-mentioned handle 45 is provided at the upper end, and left and right skis 44, 44 are connected to the lower end so as to be interlocked.

In this embodiment, the engine 1 is a two-stroke engine, and the front cylinder 2a located on the far side from the sheave 4 is tilted forward and extends in the front-rear direction, and is slightly tilted from the horizontal direction.
The rear cylinder 2b, which faces upward and is located closer to the sheave 4, stands upright in the vertical direction and is tilted slightly forward from the vertical direction.

By taking this posture, the true cylinders 2a and 2b
It has a ■-shape or an L-shape with an included angle slightly smaller than 90''.In this way, exhaust pipes 6a and 6b are connected to the sides where the true cylinders 2a and 2b face each other, respectively. An intake siren surf is provided in the rear upper region of the engine 1, and a starter motor 8 is provided at the lower rear end.

Further, the true cylinders 2a and 2b are surrounded by hoods, and a cooling fan 9 is installed in the space between these true cylinders, and this cooling fan 9 communicates with the outside of the shroud 43 via a hood (not shown). There is. Therefore, as the cooling fan 9 rotates, outside air is actively introduced, and the true cylinders 2a, 2b are cooled.

The true cylinders 2a and 2b have pistons 10a and 10l, respectively.
Qb is inserted into these pistons 10a.

The small ends of connecting rods 11a and 11b are connected to 10b, respectively, and the large ends of connecting rods 11a and 11b are connected to crankshaft 3 passing through crank case 12. One crankcase 12 is provided so as to be shared by the true cylinders 2a and 2b, but inside thereof there are two crank chambers 12 corresponding to the true cylinders 2a and 2b.
It is divided into a and 12b.

These two crank chambers 12a, 12b have intake passages 16a, 1 at the boundary where they connect with the cylinders 2a, 2b, respectively.
The connection end of 6b is open, and check valves (reed valves) 13a and 13b are connected to the connection portion. A manifold 14a is provided upstream of these check valves 13a and 13b.

The carburetors 15a, 15b are connected via the carburetor 14b, and these carburetors 15a, 15b are further connected to one intake siren surf common to both carburetors.

In forming the intake passages 16a and 16b as described above, the carburetor 15b of one of the rear cylinders 2b is connected laterally, with the intake passage 16b facing in the left-right direction. For such attachment, the manifold 14b is bent to approximately 90 degrees so that its upstream opening faces sideways. Similarly, the carburetor 15a of the front cylinder 2a is also connected laterally, and its intake passage 16a faces in the left-right direction. Similarly, the manifold 14a is bent by about 90 degrees, and its upstream opening is oriented laterally. In particular, the latter carburetor 15a on the side of the front cylinder 2a has its intake passage facing the side surface of the rear cylinder 2b, and is positioned so as to overlap with the rear cylinder 2b when viewed from the side. That is, as a result, the carburetor 15 on the rear cylinder 2b side
It is positioned further forward than b.

As mentioned above, in the intake system of the front and rear type multi-cylinder engine, the carburetor 15b of the rear cylinder 2b is installed laterally at the rear of the rear cylinder 2b, compared to the conventional one installed front and rear. The length in the front-back direction is shortened. on the other hand,
The carburetor 15a of the front cylinder 2a is also the same as the carburetor 1 of the rear cylinder 2b.
Since the carburetor 15b is installed horizontally near the rear cylinder 5b and is positioned so as to overlap with the rear cylinder 2b when viewed from the side, the carburetor 15b does not protrude further rearward than the carburetor 15b on the rear cylinder 2b side. . Therefore, compared to the conventional intake system for front and rear type multi-cylinder engines, there is much more space available at the rear of the engine. By increasing the volume of the noise reduction function, it becomes possible to increase the noise reduction function.

Furthermore, by arranging the revaporizers 15a and 15b as described above, the intake passages 16a and 16b are connected to the crank chamber 12.
piston 10a from the position opening to a, 12b,
It becomes possible to make the distance up to 10b the same for both cylinders, and thereby it becomes possible to eliminate variations in output between both cylinders.

Further, in the above-mentioned intake system, the carburetor 1 of both cylinders 2a and 2b is
Since 5a and 15b are arranged centrally, it is advantageous in terms of layout, and the intake silencer or air cleaner can be shared.

In addition, although the above-mentioned embodiment explained the case of an engine mounted on a snowmobile, the present invention can also be applied to an engine mounted on other vehicles such as a motorcycle. Also, I explained the case of a two-cylinder engine, but
If the engine is a front and rear V-type engine, the present invention can be similarly applied to three or more cylinders.

〔Effect of the invention〕

As described above, in the intake system of the vehicle-mounted front and rear V-type multi-cylinder engine according to the present invention, among the front and rear V-type multi-cylinders, the carburetor of the rear cylinder is disposed laterally at the rear of the cylinder,
The front cylinder carburetor is placed horizontally near the rear cylinder carburetor,
In addition, since it is arranged so as to overlap with the rear cylinder in side view, it becomes possible to provide further space at the rear of the engine.

Therefore, the extra space allows the engine mounting position to be moved to the rear, or the capacity of the intake silencer or air cleaner to be expanded. Furthermore, it is possible to eliminate variations in output between cylinders.

[Brief explanation of the drawing]

Fig. 1 is a side view showing the inside of the vehicle body of a snowmobile according to an embodiment of the present invention, Fig. 2 is a longitudinal sectional view showing the mounted L tank engine in cross section along the crankshaft direction, and Fig. 3 is a side view showing the inside of the vehicle body of a snowmobile according to an embodiment of the present invention. FIG. 4 is a vertical cross-sectional view showing the engine's crank chamber exhaust section along the crankshaft direction; FIG. FIG. 5 is a longitudinal sectional view of the same engine in a section perpendicular to the crankshaft at the rear cylinder portion, and FIG. 6 is a side view of a snowmobile equipped with the same engine. 1... Engine, 2a... Front cylinder, 2b... Rear cylinder, 3... Crankshaft, 7... Intake silencer,
12...Crank case, 12a, 12b...Crank chamber, 14a, l4b...Manifold,
15a, 15b...carburizer, 16a, 16b...intake passage. Agent Patent Attorney Nobuo Ogawa −

Claims (1)

[Claims] Among the front and rear V-type multi-cylinder cylinders, the carburetor of the rear cylinder is disposed laterally at the rear of the rear cylinder, while the carburetor of the front cylinder is disposed laterally near the rear cylinder carburetor, and in side view, the carburetor of the rear cylinder is arranged horizontally in the rear of the rear cylinder. An intake system for a front and rear V-type multi-cylinder engine mounted on a vehicle, characterized by being arranged in an overlapping manner.