JPS5946359A - V-type 2-cycle internal-combustion engine for autobicycle - Google Patents

Abstract

PURPOSE:To prevent an interference between an intake system and a body of autobicycle by a method wherein the intake ports are opened in V-shaped space formed between both cylinder blocks and a reed valve is installed at each of the intake ports. CONSTITUTION:An intake port 24 is arranged such that it may be opened at V- shaped space 30 defined between the first and second cylinder blocks 161, 162 and the third cylinder block 162, and then a reed valve 29 is installed at the end of the port. The reed valve 29 is fixed to the cylinder block 161 by a bolt 35 along with an intake pipe 34, and a carburettor 31 is connected to the intake pipe 34 at the V-shaped space 30. The intake port of each of the cylinder blocks is opened at the V-shaped space formed between both cylinder blocks, and a reed valve preventing a back-flow of intake mixture is installed at each of the intake ports at the V-shaped space, so that it becomes possible to install each of the cylinder blocks at the V-shaped space of the intake system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a V-type two-cycle internal combustion engine for motorcycles, which has at least two printer blocks arranged in a V-shape.

Generally, the intake system of a two-stroke internal combustion engine is equipped with a carburetor and a valve that prevents the backflow of the air-fuel mixture supplied from the carburetor to the crank chamber. It is inevitable that it will be longer than that of the Seikle engine. For this reason, especially when a V-type two-cycle internal combustion engine as described above is mounted on a motorcycle, it is difficult to arrange an intake system with long cylinder blocks without interfering with the vehicle body.

Therefore, the present invention provides the V-type internal combustion engine, which enables the intake system of each cylinder block to be disposed in the V-shaped space between both cylinder blocks, thereby easily avoiding interference between the intake system and the vehicle body. The purpose of this system is to open the intake port of each cylinder block in the V-shaped space formed between both cylinder blocks. The boat is equipped with a valve that prevents the intake air-fuel mixture from flowing backwards.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG.
crankshaft 1 and the output shaft 2 of the transmission driven by the crankshaft 1
The output shaft 2° is arranged parallel to the axles 3f and 31- of the front and rear wheels If/f and IFγ, and the output shaft 2° drives the rear wheel 1/'7 via the chain transmission 4.

As shown in FIGS. 2 and 3, the illustrated example internal combustion engine E is configured as a three-cylinder type, and its crankshaft 1 has three crank pins 5. ．． 52.5. are aligned on the same axis, and the crank pins 5. ．． 52 as the first and second crank pins, and the crank pin 5 in the center position.
3 is called the third crank pin.

A generator 6 is attached to the left end of the crankshaft 1, and a drive gear 7 is attached to the right end, and the drive gear 7 meshes with a driven gear 8 of a clutch 9 provided on the input shaft 2i of the transmission.

The crankshaft 1 is supported by a crankcase 11 via four bearings 10, 10, . . . . Four bearings io, io... are three crank pins 5+, 52
．． The interior of the crankcase 11 is partitioned between the first and second bearings by partition walls that support these bearings. Second. 3rd crank bin 5+, 52. 53
1st and 2nd respectively. 3rd crank chamber 12□
, 122.12. It is divided into

1st. Second. The third crank bins 5□, 5□, 53 have the first. Second. Third piston 13. ．． 13□.

133 is the first. Second. Third connecting rod 14. ．． 142°143 and 1st. Second. Third piston pin 151.

152.153 via 1st. Second. 3rd piston 13
+, 132. 133 are connected to each other, and these pistons 1.3+, 132 . 133 slides together. Second. Third cylinder block 16. ．． 162°16
3 is fixed to the crankcase 11. At that time, the first and second cylinder blocks 16. ．． 1lli2 is placed horizontally so as to face the front of the vehicle, and the 37th ring block 16.
are each vertically arranged to face upward, thus the first and second cylinder blocks 16. ．． 162 and the third cylinder block 16° are V with a bank angle of 90°.
arranged in a letter shape.

1st. Second. Third cylinder block 16+, 16t.

The outer periphery of the tip of 163 has the first. Second. 37th ring head 171.172. 173 is screwed on, and further these cylinder heads 1L, 172.1γ.

Water jacket around 18+, 182, 18
7z forming a, 2nd. Third head cover 191.

19,. 193 is attached to P 1st. Second. Third cylinder head 1γ,, 172.173. There are 1st and 2nd. Third spark plug 20. ．． 20□, 203 are screwed, and these spark plugs 20I, 202, 203 are connected to the first and second cylinder heads 17. ．． Combustion chamber 21 in 17□. ,'21□
An ignition control device (not shown) is configured to cause simultaneous explosions at the combustion chamber 213 in the third cylinder head 173 and to provide a phase difference of 900 degrees in crank angle between these explosion timings and the explosion timing in the combustion chamber 213 in the third cylinder head 173. controlled by

First and second pistons 13. ．． The reciprocating masses of the 13□ systems are made equal to each other, and the sum of these reciprocating masses and the reciprocating mass of the third piston 133 system are made substantially equal to each other. In the illustrated example, in order to satisfy such conditions, the first and second
While the piston pins 151 and 152 are formed hollow,
The third piston pin 153 is formed to be larger in diameter and solid than those, and the singing part 143cL of the third connecting rod 143 is
are the first and second connecting rods 14. ．． Small end 14 of 142
, a, and is formed to have a larger diameter than 142a.

The crankshaft 1 has a pair of first, second, and third crank webs 22+, 221'; 222, 222' supporting three crank pins "l+52+53," respectively.
22,. 223, with the rotation center of the crankshaft 1 sandwiched between them. Second. 3rd crank pin 15, . 52.
5. The first . Second. Third
Balance way l-23,,23,';232. 23
2'; 233, '233 are arranged in series, and these balance weights are such that the sum of the centrifugal force during their rotation is the first and second biston weights 13. ．． 132 system primary inertia force and third piston 13. They are formed so that they are approximately balanced with the primary inertial force of the system, and the overall mass distribution is symmetrical.

Note that the magnitude of the -th order inertial force is expressed by the product of the reciprocating mass of the piston system and its acceleration.

Furthermore, the first. Second. 3rd balance weight 23+
, 23+'; 232. 232';233.23'
3 has the 1st. Second. A mass equal to 50 to 100% of the rotating mass of the third crank pin J+52$53 system is added to balance the crankshaft 10 rotations.

Each cylinder block 161 (the same goes for 162, 16a) has an intake boat 24 that communicates with the crank chamber 121 of the same type, and a combustion chamber 21 of the same type that connects the crank chamber 12°. A pair of left and right scavenging ports 25.25 communicate with the combustion chamber 21. An exhaust boat 24 is provided which connects the first and second cylinder blocks 16. to the exhaust pipe 26 or 27 (see FIG. 1).
．． The cylinder block 162 and the third cylinder block 163 are provided so as to open into the V-shaped space 30 defined between the cylinder block 162 and the third cylinder block 163, and a gate valve 29 is attached to the open end thereof. This reed valve 29
Valve surface 29. Z is connected to the cylinder block 16 by bolts 35 together with the intake pipe 34. Further, a carburetor 31 is connected to the intake pipe 34 in the V-shaped space 30.

The air cleaner 32 connected to the intake port of the carburetor 31 is
As shown in Figures 1 and 1α, it is arranged between the pair of left and right main tubes Fa in the vehicle body frame F, and is placed on the pair of cross members Fd, and is attached to the front end of the air leak 32. The piece 32a is fixed to the patch 36 at the front end of the main tube Pa with a screw 37.

The pair of cross members Fd connects the pair of stays Fc that connect the left and right main tubes Fa and the left and right down tubes Fb, respectively. The air population 32b of the air cleaner 32 opens toward the rear of the vehicle.

Therefore, during operation in mode E, the first cylinder block 1
6. Speaking of the side, the piston? During the 3° upward stroke, the crank chamber 12. Since the pressure is reduced, the air-fuel mixture generated in the carburetor 31 passes through the reed valve 29 and the intake boat 24 to the crank chamber 12. The piston 13. Since the crank chamber 12 is pressurized during the descending stroke, the air-fuel mixture pressurized here passes through the scavenging bow) 25.
Filled to 1. At this time, since the reed valve 29 closes in response to the pressure of the pressurized air-fuel mixture, it is possible to prevent the air-fuel mixture from flowing back toward the carburetor 31 side. Combustion chamber 211
The air-fuel mixture filled in the piston 131 is compressed in the next upward stroke of the piston 131, and then ignited by the discharge from the spark plug 2, resulting in combustion (
Explosion) to apply a downward force to the piston 131, the exhaust boat 28 opens during the downward movement of the piston 131, and the exhaust gas from the combustion chamber 21 is then discharged. 2nd and 3rd
Cylinder block 162-16s ff1ll The same action is performed.

During this time, balance weight 231.231'; 232
．． 232';233. 231 group is the first and second cylinder block 16. ．． 162, their centrifugal force is applied to the first and second pistons 131.
．． The overall -order inertia force of the 132 system is balanced 1, and the above balance weight group is the third cylinder block 16. When the centrifugal force reaches the vertical plane I-, which includes the center line of

Also, first and second pistons 13, . 1
The resultant force of the primary inertial force of the 3□ system acts on the center of the crankshaft 1, and the primary inertial force of the third piston 133 system at the center also acts on the center of the crankshaft 1, and its point of action is always stationary. On the other hand, the balance weight is 2.3+
, 23+'; 232 -23□'; 233.233
Since the overall mass distribution is symmetrical, the centrifugal force caused by these forces is also concentrated at the point of action on the crankshaft 1.
No couple occurs in .

1st. Second. Third cylinder block 16. ．． 162゜1
63 (・piston 13+, 132 2.13
If the stroke volumes of the crank chambers 12.3 and the compression ratios of the combustion chambers 211, 212, and 213 are equal, respectively, then ．．
If the compression ratios of 12□ and 123 are different, the combustion chamber 2
1+, 212. This is not desirable because it causes a difference in the explosive power of the mixture at 21s. However, as mentioned above, the first and second pistons 13□.

In order to equalize the total reciprocating mass of the 132 series and the reciprocating mass of the third piston 133 series, the piston pin 153 and connecting rod small end 143a of the third piston 133 series are formed to have a larger diameter than those of the other systems. Accordingly, the effective volume of the third crank chamber 123 is larger than that of the other crank chambers 121 . 1
22, so the third crank chamber 12. The compression ratio of the crank chambers 121 and 122 is larger than that of the other crank chambers 121 and 122.

In order to correct this difference in compression ratio between the rank chambers, the third crank chamber 12. The width (axial length) of the third balance weight 23. is made longer than each of the other crank chambers 12□, 122, and +.

23, the total thickness of other balance weights 23. .

23+'; 232 and 232', the third crank chamber 123 and the third balance weight 23. ．． 233 and the other crank chambers 12+, 122 and other balance ways) 23. ．． 23
1';232. It is effective to make the space larger than the respective gap volumes with 23□'. This is advantageous in processing since the radial gap between each crank chamber and the balance weight may be constant.

In this case, in order to make the width of engine E as short as possible,
] and second crank web 22. ．． 22. ';22
2. At 22□' each inner web 22□i, '222
It is advantageous to make t thinner than each outer web 221,222. That is, by doing this, the inner web 22+
1st by thinning '-22□'. Second cylinder block 16. ．． The distance between 16* can be reduced.

Furthermore, in this case the thin inner web 22. ', 2 “2
2' and crank bins 58, 5□ are each integrally formed, and the tips of these crank bins 51, 52 are connected to thick outer webs 22.2'. ．． By press-fitting into the coupling holes 33 and 33□ of 222, a sufficient press-fit depth can be obtained.
This is effective in obtaining a prefabricated crankshaft 1 with high coupling strength of the crankbin.

As described above, according to the present invention, in a V-type two-stroke internal combustion engine having at least two cylinder blocks arranged in a V-shape, the V
Open the intake boat of each cylinder block in the letter-shaped space,
Since each intake boat in the L/shaped space is equipped with a reed valve that prevents the intake air-fuel mixture from flowing back, the intake system of each cylinder block, including the reed valve, is not allowed to flow into the V-shaped space. Interference between the intake system and the vehicle body can be easily avoided, and by extension, the vehicle body can be made smaller.

[Brief explanation of the drawing]

Figure 1 is a side view of a motorcycle equipped with a 1/2 cycle internal combustion engine based on an embodiment of the present invention, Figure 1a is a plan view of its main parts, and Figure 2 is a longitudinal cross-section of the main parts of the engine. The plan view and Fig. 3 are cross-sectional views taken along the line of Fig. 2. E...V-type two cycle internal combustion engine, 1... Crankshaft,
11... crankcase, 12. ~12. ...First
~3rd crank chamber, 131-133...1st-3rd piston/, 16. ~163...First to third cylinder block, 24...Intake boat, 29...Reed valve, 3
0...V-shaped space, 31...Carburizer, 32...Air tank 17- Patent applicant Honda Motor Co., Ltd.

Claims (1)

[Claims] In a V-type two-cycle internal combustion engine having at least two cylinder blocks arranged in a V-shape, an intake boat of each cylinder block is placed in an I-shaped space formed between the two cylinder tabs and one cock. A V-type two-cycle internal combustion engine for a motorcycle, characterized in that each intake boat in the V-shaped space is equipped with a one-stop valve for preventing backflow of the intake air-fuel mixture.