JP2836697B2 - Intake device for two-cycle V-type engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for a two-cycle V-type engine suitable for a motorcycle, and more particularly, to an intake port arranged in parallel in a V-bank portion of a crankcase. In particular, the present invention relates to a structure in which the opening area of the intake port can be enlarged by increasing the dimension (opening height) of the intake port in a direction perpendicular to the crankshaft.

[Conventional technology]

As an intake device for a two-cycle V-type engine, there is an intake device in which an intake port communicating with a crank chamber is formed in a portion inside a V bank of a crankcase, and an air-fuel mixture is directly introduced into the crankcase. In such an intake device,
In order to avoid interference between the carburetor and the cylinder head or the like, the carburetor for the upper cylinder may be displaced downward and the carburetor for the lower cylinder may be displaced upward. In this case, for example, as shown in FIG. 11, the upper cylinder intake port 73 has its center line L2 extending upward in the crankshaft direction, and the lower cylinder intake port 74 has its center line L2 upward. It is formed so as to be displaced so as to be located, and a displacement difference D occurs between the two openings. Reference numerals 75 and 76 denote reed valves mounted on the respective intake ports 73 and 74, and their flanges 75a and 76a are attached to the mounting seat surfaces 73a and 73.
It is bolted and fixed to 4a. Reference numerals 71 and 72 are connection openings for upper and lower cylinders.

[Problems to be solved by the invention]

In order to improve engine performance, it is important to introduce a larger amount of air-fuel mixture into the crankcase by increasing the opening area of the intake port. However,
When the upper cylinder intake port 73 and the lower cylinder intake port 74 are displaced downward and upward, respectively, as in the case of FIG. 11 described above, the lower edge and the upper edge position of the intake port are lower, Due to restrictions on the relationship with the upper cylinder, there is a case where the inside of the bank of the crankcase cannot be sufficiently used as an opening, the opening height H of each of the intake ports 73 and 74 becomes low, and eventually the opening area cannot be sufficiently secured. Occurs. In particular, when the bank angle is as small as 90 degrees or less, there is a concern that a necessary opening area cannot be secured because the area itself of the crankcase inside the bank is not sufficient.

The present invention has been made in view of the above conventional problems,
In particular, there is provided an intake device for a crankcase lead type two-stroke V-type engine in which an opening area can be enlarged by effectively utilizing an inner portion of a bank of a crankcase to secure a sufficient opening height of an intake port. It is intended to be.

[Means for solving the problem]

The present invention provides a crankcase in which an intake port communicating with a crank chamber is formed in a portion inside a V-bank of a crankcase, and a reed valve is provided in the intake port to directly introduce an air-fuel mixture into the crankcase. Lead type 2 cycle V
In the intake device of a type engine, the intake ports for the respective cylinders are formed in parallel at the center of the V-bank of the crankcase so that the mounting seat surface for the reed valve is parallel to the crankshaft. It is characterized in that the center lines in the respective crankshaft directions above form the same straight line.

Here, in the present invention, the phrase that each crank axis direction center line is the same straight line means that each mounting seat surface is the same plane, and that each mounting seat surface is in the upper cylinder direction around the crank axis direction center line. , And both cases where the motor rotates by a predetermined angle in the direction of the lower cylinder.

[Action]

According to the intake device of the present invention, since the center line in the crankshaft direction on the mounting seat surface of each intake port forms the same straight line, the lower edge of each intake port, the lower side of the upper edge position, and the upper cylinder , The opening height can be increased by making full use of the inside of the bank of the crankcase, and the opening area can be increased accordingly.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 to 9 are views for explaining an intake system of a two-stroke V-type engine for a motorcycle according to an embodiment of the present invention. FIG. 1 is a front view of an intake port, FIG.
3 is a partial left and right side view, FIGS. 4 to 7 are views showing a reed valve, FIG. 8 is a sectional plan view of a crankshaft portion, and FIG. FIG. 2 is a left side view of the motorcycle.

In the drawing, reference numeral 1 denotes a motorcycle employing the apparatus of this embodiment, and a body frame 2 of the motorcycle is connected to a head pipe 2a by welding the front ends of a pair of left and right main frames 2b having a rectangular cross section in a rectangular shape. The rear arm brackets 2c welded to the rear end of the main frame 2b are connected to each other by a cross pipe (not shown). A radiator 31 is bridged between the lower surfaces of the left and right main frames 2b, and is supported by brackets 2d fixed to both frames 2b. The head pipe 2a supports a front fork 4 that supports the front wheel 3 at the lower end so as to be steerable left and right. The rear arm bracket 2c has a rear wheel 5 at the rear end.
Is pivotally supported up and down freely. In addition, 7 is a fuel tank and 8 is a seat.

The left and right lower portions of the left and right main frames 2b and the front portion of the head pipe 2a are surrounded by a cowling 9, in which a water-cooled two-cycle V-type two-cylinder engine 10 is suspended and supported. ing. This engine 10
Crankcase 11 divided into front and rear cases 11a and 11b
The upper cylinder 12a and the upper head 12b are stacked diagonally upward on the connection opening 11c formed on the upper part of the front case 11a, and connected with the head bolt 14, and the connection opening 11d formed on the lower part. The lower cylinder 13a and the lower head 13b are stacked diagonally downward and connected by a head bolt 14.

Here, the bank angles formed by the axes A1, A2 of the cylinders 12a, 13a are 90 degrees, and when viewed from the front of the vehicle (the same applies hereinafter), the upper cylinder 12a is on the right, and the lower cylinder 13a is on the left. Is located. The head bolts 14 are implanted in screw holes 11h and 11i formed at four corners of the periphery of the connection openings 11c and 11d, respectively. The bolt hole 11h 'located on the side is located closer to the other cylinder than the center line D. Reference numerals 11j and 11k denote bolt holes for tightening crankcases formed inside and outside the connection openings 11c and 11d of the front case 11a.

Pistons 15a, 15b slidably inserted into the cylinders 12a, 13a are connected to the front and rear cases 11a, 11b of the crankcase 11 via connecting rods 16a, 16b in the vehicle width direction. And is connected to a crankshaft 17 that is disposed.

The crankshaft 17 is formed by assembling an upper crankshaft 41 for an upper cylinder and a lower crankshaft 42 for a lower cylinder by press-fitting at the center. The lower crankshaft 44 is assembled by press-fitting the outer and inner shaft portions 45, 46. That is, the crankshaft 17 is a four-piece assembly type crankshaft, and the crank web 4 of the upper and lower crankshafts 41 and 42 is used.
The outer parts of 1b and 42b are roller bearing 52a and ball bearing, respectively.
The portion between the two crank webs is supported by a roller bearing 52c. The upper and lower connecting rods 16a and 16b are connected to crank pins 44a and 46a of upper and lower crankshafts 41 and 42, respectively, and the respective crank webs 41b and 42b are connected to the front and rear cases 11a and 11b, respectively. , 11b are housed in crank chambers 11e, 11f.

On the upper side of the rear case 11b and in the vicinity of the division surface 11l, a balancer chamber 11g is formed so as to protrude so as to extend in parallel with the crankshaft 17, and a balancer shaft 47 is inserted into the balancer chamber 11g. ing. Both ends of the balancer shaft 47 are supported by bearings 50. A balancer weight 51a is attached to a portion of the balancer shaft 47 projecting outward from the bearing 50, and is fixed by a nut 51b. And a driven gear fixed to the balancer shaft 47.
48 meshes with a drive gear 49 of the crankshaft 17.

Upper and lower intake ports 32a and 32b are formed in the inside of the bank of the front case 11a.
2a and 32b communicate with the crank chambers 11e and 11f, respectively. The mounting seat surfaces 32c, 32c of the intake ports 32a, 32b for mounting the reed valves described later have rectangular shapes that are long in the crankshaft direction. The center D 'of the opening on each mounting seat surface is located on the bisector B of the bank angle, and the center line C in the direction of the crankshaft continuously forms the same straight line on both the left and right sides. It is parallel to 17. Further, an inner side portion 32d of the mounting seat surface 32c located on the engine center line D is common to the left and right. In this way, each intake port 32a, 32b is arranged in parallel in the crankshaft direction,
And the same opening area, each mounting seat surface 32c
Are in the same plane.

Here, when the front case 11a is viewed from the side, it is substantially an isosceles triangle. In addition, the mounting seat surface 32c of the intake port and the dividing surface 11l of the front case 11a are parallel to each other. The angle between the division surface 11l and the axes A1 and A2 is 45
Degree.

The upper valve body 18 and the lower valve body 19 of the integrated reed valve 53 are inserted into the intake ports 32a and 32b. This reed valve 53
Of the upper frame portion 54a and the lower frame portion 54b
It is integrated by c. When viewed from the side, the upper and lower frame portions 54a and 54b have their vertices upward and downward, respectively.
It has a triangular shape deviated downward, and a valve plate 21 that opens and closes an opening 54d formed in this portion is provided on the ridge surface of the guide plate 2.
It is fixed together with 2. And the upper and lower valves 18,19
Is mounted horizontally, that is, mounted so that the ridge surface is parallel to the crankshaft, and the vertices are upper and lower cylinders.
It points to 12a, 13a side.

The leading ends of the cab joints (intake pipes) 23 and 24 are inserted into the reed valves 18 and 19, and the respective flange portions 23b and 24b are attached to the mounting seat surface 32c together with the flange portion 54c of the reed valve 53. Fixed. Each of the cab joints 23, 24 is bent left and right outward when viewed from a plane,
When viewed from the side in the crankshaft direction, the bisector B
It extends forward on top. Vaporizers 25 and 26 are attached to the tips of the cab joints 23 and 24, respectively. In each of the carburetors 25 and 26, the axis of the intake passage is slightly lower than the bisector B, and is located at the same height when viewed from the side. Furthermore, an air cleaner 27 disposed inside the cowling 9 is connected to each of the vaporizers 25 and 26.

 Next, the operation and effect of this embodiment will be described.

In the intake device of the present embodiment, when the pressure in the crank chambers 11e, 11f becomes negative with the rise of the pistons 15a, 15b, each valve element 18,
19 is opened, and after the outside air is filtered by the air cleaner 27, it is introduced into the carburetors 25 and 26, where the fuel is mixed to form an air-fuel mixture, and the air-fuel mixture is mixed with the cab joints 23 and 24 and the valve bodies 18 and 19.
Then, it is sucked into the crank chambers 11e and 11f and then introduced into the cylinder from the scavenging passage.

In the intake device according to the present embodiment that performs such an operation, the opening centers D ′ of the intake ports 32a and 32b are located on the bisector B of the bank angle when viewed in the crankshaft direction. 32
Since the center lines C in the crankshaft direction on the mounting seat surface 32c of b are formed so as to form the same straight line, the inside of the bank of the front case 11a is used as an intake opening without waste and each intake port is used.
The opening height H of the openings 32a and 32b can be sufficiently ensured. Also, since the inner side portion 32d of the mounting seat surface 32c is shared by the left and right, the opening width W can be enlarged as compared with the case where the mounting seat surface is individually provided,
As a result, the opening area can be increased.

Since the reed valve 53 is an integral type in which the upper and lower frame portions 54a, 54b are integrated with a flange portion 54c, the inner side portion 32d of the mounting seat surface 32c is shared by a narrower one. Can be If a separate reed valve is attached to each intake port, as shown in FIG. 11, the respective mounting flange portions 75a 'and 76a of the reed valves 75 and 76 are used as inner side portions of the mounting seat surface. ', And the width of the opening cannot be increased so much.

In the above embodiment, the mounting seat surface 32c of each intake port 32a, 32b is provided.
Have been described as having the same plane, but the intake port according to the present invention is not limited to the fact that the center line C in the crankshaft direction on the mounting seat surface may be the same straight line. No need to do. For example, as shown in FIG. 10, the mounting seat surfaces 32c of the upper and lower cylinder intake ports 32a and 32b may be rotated downward and upward by a predetermined angle around the center line C in the crankshaft direction.

In this case, there is an effect that the opening area can be sufficiently secured as in the above-described embodiment, and the carburetor is biased downward and upward according to the rotation angle of the mounting seat surface while using a cab joint having the same shape. And parts can be shared.

〔The invention's effect〕

As described above, according to the intake system for a two-stroke V-type engine according to the present invention, the center lines in the crankshaft direction on the mounting seat surfaces of the upper and lower cylinder intake ports are made to be the same straight line. The opening height of each intake port can be increased by effectively utilizing the portion inside the V bank of the crankcase, and there is an effect that the opening area is sufficiently secured to improve the engine performance.

[Brief description of the drawings]

1 to 9 are views for explaining an intake device of a two-cycle V-type engine according to one embodiment of the present invention,
FIG. 1 is a front view of an intake port portion, FIG. 2 is a partially sectional left side view, FIG. 3 is a partially sectional right side view, and FIGS. 4 to 6 are front views of a reed valve frame. FIG. 7 is a plan view, a right side view, FIG. 7 is a sectional view taken along line VII-VII of FIG. 5, and FIG.
FIG. 9 is a left side view of the motorcycle employing the apparatus of the embodiment, FIG. 10 is a schematic view showing a modified example of the shape of the mounting seat surface of the intake port, and FIG. 11 is a conventional problem. It is a front view of the intake port part for demonstrating a point. In the figure, 10 is a two-cycle V-type engine, 11 is a crankcase, 11e and 11f are crank chambers, 12a and 13a are upper and lower cylinders, 18 and 19 are upper and lower valve bodies (reed valves), 32a and 32b is an intake port, 32c is a reed valve mounting seat surface, and C is a center line in the crankshaft direction.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02B 25/28 F02B 25/14 B62M 7/02 F02B 25/20

Claims (1)

(57) [Claims] A plurality of cylinders are arranged so as to form a V-bank, and an intake port communicating with a crank chamber is formed in a portion of the crankcase inside the V-bank, and an air-fuel mixture flows from the intake port into the crankcase. In the intake device of a crankcase lead type two-cycle V-type engine which is directly introduced, the intake ports for the respective cylinders are arranged in parallel at the center of the V bank of the crankcase such that the mounting seat surface for the reed valve is parallel to the crankshaft. And a center line in the direction of each crankshaft on each of the mounting seat surfaces is formed on the same straight line.