JPS5947547A - Three cylinder type internal-combustion engine - Google Patents

Abstract

PURPOSE:To restrain vibration caused by primary inertia force, by arranging cylinder blocks respectively formed with two and one cylinders, in the horizontal and vertical directions, respectively, at a bank angle of 90 deg., and by providing specific balance weights to a crank shaft. CONSTITUTION:Three pistons 131 through 133 are coupled, respectively through connecting rods 141 through 143 to crank pins 51 through 53 coaxially arranged on a crank shaft 1. Further, cylinder blocks 161, 162 respectively receiving the pistons 131, 132 are arranged in the substantial horizontal direction, and a cylinder block receiving the piston 133 is arranged between the blocks 161, 162 in the substantial vertical direction so that the block 163 is set at a bank angle of 90 deg. with respect to the blocks 161, 162. The total reciprocating mass-weight of first and second piston systems including pistons 51, 52 is made substantially equal to the reciprocating mass-weight of a third piston system including the piston 53, and as well, balance-weights 231 through 233, 23'1 through 23'3 which substantially balance with the inertia force of the first and second piston systems and that of the third piston system, respectively, are arranged to the crank shaft 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-cylinder internal combustion engine that eliminates vibrations caused by secondary force.

Conventionally, in a three-cylinder internal combustion engine, it is known that three crank pins are arranged at an interval of 120° above the crank angle to remove vibrations caused by the primary inertia force. There is a drawback that an unbalanced couple is generated on the crankshaft due to the phase shift of the pins.

An object of the present invention is to provide a simple and effective three-cylinder internal combustion engine that eliminates vibrations caused by -order force without generating such an unbalanced couple.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a three-cylinder internal combustion engine E of the present invention is mounted on a body frame F of a motorcycle, and a crankshaft 1 of this engine E and a transmission driven by the three-cylinder internal combustion engine E are mounted on a body frame F of a motorcycle. The output shaft 2° of the machine is arranged parallel to the axle 3f, >3γ of the front and rear wheels FfjWr, and the output lpH12o is transmitted to the rear wheel IF via the chain transmission device 4.
Drive r.

As shown in Figs. 2 and 3, the three-cylinder internal combustion engine E has two
The crankshaft 1 has three crank pins 5. +52 and +53 are aligned on the same axis, and the crank pins 5. +5
2 are called first and second crank pins, and the crank pin 53 at the center position is called a 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 the crankcase 11 via four bearings 10110. Four bearings 10ν1υ... are three crank pins 5°+52+5.
The interior of the crankcase 11 is arranged so as to sandwich the bearings between the bearings, and the partition walls that support these bearings make the inside of the crankcase 11
The 1st), 2nd and 3rd crank chambers 12. accommodate the 22nd and 3rd crank bins 51, 5□ and 53, respectively. Tsu122
It is divided into A 123.

The 1st, 2nd, and 3rd crank pins 5+ 152253 are connected to the 1ν, 22nd, and 3rd pistons 13++132+133. +14□2143 and 1st. Second. 3rd piston pin 151°152.15
1 through 3. Second. Third piston 131 Tsu 13
2.133 are connected to each other, and these pistons 13□
, 13°, and 133 slide together. A third cylinder block 16+ + 162163 is fixed to the crankcase 11. At that time, the first and second cylinder blocks 16. ．． 162 are arranged so as to face the front of both cylinder blocks, and the third cylinder block 163 is arranged so as to face upward, so that the first and second cylinder blocks 16
, 16□ and the third cylinder block 163 are arranged in a V-shape with a bank angle of 90 degrees.

12th 2nd. Third cylinder block 16. , 16□.

The outer periphery of the tip of 163 has the first. Second. A third cylinder head 17+ + 1-72 + 173 is screwed on, and these cylinder heads 17 + + 172 .
The first pipe forms a water jacket 18□, 182.183 around 1L. Second. Third head cover 19□.

192 and 193 are installed. 1st. Second. Third cylinder head 17z + 172. 173 has the 1st degree and the 2nd degree. Third spark plug 20. ν20□, 203 are screwed to these spark plugs 20. ．． 20□, 203 are the first and second cylinder heads 171 . Combustion chamber 21 in 172
□, 21□ to cause simultaneous explosions, and the timing of these explosions and the third cylinder head 17. Combustion chamber 2 inside
It is controlled by an ignition control device (not shown) to provide a phase difference of 90° in terms of crank angle between the explosion timing at 13 and the explosion timing at 13.

The reciprocating masses of the first and second pistons 13I, 132 are made equal to each other, and the sum of these reciprocating masses and the third piston 13. The reciprocating masses of the system are made approximately equal to each other.

In the illustrated example, in order to satisfy such conditions, the first and second piston pins 151 and 152 are formed hollow, while the third piston pin 153 is formed solid and has a larger diameter than the first and second piston pins 151 and 152. Small end 143a of 3 connecting rod 143
are the small ends 14 of the first and second connecting rods 1'hr14□
It is formed to have a larger diameter than 1a7 142CL.

Crankshaft 1 has three crank bins s, t 52°53
The first . of each pair respectively supports . Second. 3rd crank web 221, 221';222.222'; 22s
+22s, and the first. Second. 3rd crank pin 51.5□, 53
The first . Second. Third balance weight 23. +23. ';232. 232
';233 F23. are arranged in series, and the total centrifugal force of these balance weights when they rotate is the first and second piston 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 mass distribution is symmetrical.

The magnitude of the -order force is expressed by the product of the reciprocating mass of the piston system and its acceleration.

Furthermore, the first. Second. Third balance weight 231.
231'; 232 123□';23. Tsu233
The first thing is. Second. 3rd crank pin5. , 52.53
A mass equal to the rotational mass of the system is added for rotational balance of the crankshaft 1.

Each cylinder block 16. [The same applies to 62, 16, etc.] The intake boat 24 communicates with the crank chamber 121 in the same row, and the crank chamber 12° is connected to the combustion chamber 21□ in the same row.
A pair of left and right scavenging boats 25, 25 are provided, and an exhaust boat 28 is provided that connects the combustion chamber 21□ to the exhaust pipe 26 or 2γ (see Fig. 1) for 1 m. A leak valve 29 is installed to prevent backflow. Each intake boat 24 is provided so as to open into a V-shaped space 30 formed between the first and second cylinder blocks 16,116□ and the third cylinder block 163, and is attached to each intake boat 24. vaporizer 31
and its air cleaner 32 are arranged in the company record space 30.

Therefore, when the engine E is operating, the first cylinder block 1
6. Regarding the side, during the upward stroke of the piston 131, the crank chamber 12. Since the pressure is reduced, the air-fuel mixture generated in the carburetor 31 passes through the intake boat 24 and the reed valve 29 to the crank chamber 12. Since the crank chamber 12□ is pressurized during the downward stroke of the piston 131, the air-fuel mixture pressurized here is filled into the combustion chamber 21□ through the scavenging port 25 + 25, and is then filled into the combustion chamber 21□ of the piston 13□. After being compressed in the upward stroke, the spark plug 20□ is ignited and combusted (exploded) by discharge, applying a downward force f=J to the piston 13□, causing the piston 13. The exhaust bow 1-28 opens in the middle of its descent, and the exhaust gas in the combustion chamber 21□ is then discharged. Second and third cylinder blocks 162.16. A similar action takes place on the side.

During this time, balance weight 23. ．． 23. ';232
F 232'; 23a + 233 groups are the first and second
When the cylinder blocks 16+ and 16□ come on a horizontal plane including their center lines, their centrifugal force is balanced with the total negative force of the first and second pistons 13+1132 system, and the balance weight group is in the third cylinder block. 16.
When the centrifugal forces are on a vertical plane containing the center line of the piston, their centrifugal forces are balanced by the primary inertial force of the third piston 13° system.

In addition, the first and second pistons 13+11 located on both the left and right sides
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 3rd system located at the center also acts on the center of the crankshaft 1, and its point of action is is always stationary, while the balance weight 23. ．．
23. ';23□.

23□'; Since the mass distribution of 23i + 233 is symmetrical, the centrifugal force caused by these is also concentrated at the point of action, and as a result, no force couple is generated on the crankshaft 1. .

1st. Second. Third cylinder block 16. , 16□.

If the stroke volumes of the pistons 13□, 13°, and 133 and the compression ratios of the combustion chambers 21+ and 163 are equal, respectively, then the crank chambers 12. ．． 1
2□ The compression ratio of TS 123 is different (・roto, combustion chamber 2
11 +212 +21s This is not desirable because it causes a difference in the explosive power of the mixture. However, as described above, the first and second pistons 131.

Total reciprocating mass of the 13□ system and the third piston 13. In order to equalize the reciprocating mass of the system, the piston pin 15. of the third piston 133 system. If the connecting rod small end 143a is formed to have a larger diameter than that of the pond type, the third crank chamber 12. The effective volume is the other crank chamber 12. ．． 12
□, the compression ratio of the third crank chamber 123 becomes larger than that of the other crank chambers 128 and 12 □.

In order to correct this difference in compression ratio between the rank chambers, the width (axial length) of the third crank chamber 123 is made longer than the widths of the other crank chambers 121.12□.
3rd balance way)23. .

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

231'; 232 >232', the third crank chamber 121 and the third balance weight 233.23. and the other crank chamber 12. ．． 12□ and other balance weights 231,2
31'; 232 J 23°' is effective. 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,
First and second crank webs 22. , 22t'; 22
□ , 222' at each inner web 22. ', 22□
It is advantageous to make l thinner than each outer web 22++22□. That is, in this way, the inner web 22.
', 222' is made thinner. The distance between the second cylinder blocks 16++162 can be shortened.

Furthermore, in this case the thin inner web 22. ′, 22□′
and crank pin 5. ．． 52 are each integrally formed,
These crank pins5. ．． If the tips of 52 are press-fitted into the joint holes 331° and 33□ of the thick outer webs 22□ and 22□, sufficient press-fit depth can be obtained, so that a prefabricated crank with good crankpin joint strength can be obtained. This is effective in obtaining axis 1.

Note that the present invention can also be applied to a 4-cycle type three-cylinder internal combustion engine, in which case the J and second cylinder blocks 16. ．． It is better to shift the explosion timing by 360° on the crank angle between 162 and 162 degrees.

As described above, according to the present invention, the first and second crank pins and the third crank pin occupying an intermediate position between these are arranged coaxially on the crankshaft, and the first and second crank pins are aligned on the same axis. First, second and third pistons are connected to second and third crank bins, respectively, and first and second cylinder blocks accommodate the first and second pistons, and a cylinder block accommodates the third piston. are arranged to open at a bank angle of 90°, so that the total reciprocating mass of the first and second piston systems and the reciprocating mass of the third piston system are approximately equal to each other, and Since a balance weight is provided on the crankshaft that approximately balances the primary inertia force of the piston system and the primary inertia force of the third piston system, the primary inertia of the first and second screw systems is reduced by using the common balance weight. It is possible to balance the force and the primary inertia force of the third piston system, respectively, and it is possible to eliminate vibrations of the engine due to the -order force.

In addition, since the point of action of the resultant force of the primary inertia force of the entire piston system is always at one point in the center of the crankshaft and does not change, by concentrating the centrifugal force of the balance weight on the one point, the It is possible to prevent the occurrence of an unbalanced couple, and it is also possible to avoid vibrations of the engine due to the unbalanced couple.

Furthermore, since the first and second cylinder blocks of the first and second piston systems, each of which has a small reciprocating mass, are arranged approximately horizontally, the lateral pressure applied to the first and second pistons due to gravity is extremely small, while the reciprocating mass The third cylinder block of the third piston system, which has a large
There is almost no lateral pressure applied to the third piston due to gravity, so there is no piston that is subjected to large lateral pressure, and power loss and wear due to the lateral pressure can be minimized.

Moreover, the IFH has a special structure compared to conventional three-cylinder internal combustion engines. It doesn't get complicated.

In addition, in the present invention, making the reciprocating mass W1 + '2 of the first and second piston systems substantially equal to the reciprocating mass W of the third piston system means that IF, +'2 This includes the case where and W are close to each other, specifically, -F3 is 117 and 1112
There is no problem in practice as long as it falls within the range of 75 to 110%.

[Brief explanation of drawings]

Fig. 1 is a side view of a motorcycle equipped with a three-cylinder internal combustion engine according to an embodiment of the present invention, Fig. 2 is a vertical sectional plan view of the main part of the engine, and Fig. 3 is a cross section taken along the line II-III in Fig. 2. It is a diagram. L゛... Three-cylinder internal combustion engine, 1... Crankshaft, 51
~53...First to third crank pins, 11...Crank coos, 12. ~12. . . . 1st to 3rd crank chambers, 13, to 13. ...first to third pistons, 14.
~143-@I ~3rd core 0tsudo, 15. ~15. . ...first to third piston pins, 16. ~163...first to third cylinder blocks, 221, 221'; 222
．． 22□'; 223.22. ...First. 2nd゜3rd
Crank web, 23+ 1231'; 23□. 232'; 23. q, +23. i... 1st. Second. ’! 3 Balance weight patent applicant Honda Motor Co., Ltd. Commissioner of the Patent Office 1. Display of the case 1982 Patent Application No. 158278 2 Name of the invention Three-cylinder internal combustion engine 3 Person making the amendment Relationship to the case Patent applicant name (532) Honda Motor Co., Ltd. 4, Representative
Mr. Hito 105 Telephone Tokyo 434-4151 5. Date of amendment order: November 12, 1980 (Shipping date: November 3, 1982)
0 days)・-291-

Claims (1)

[Claims] First and second crank pins and a third crank pin occupying an intermediate position therebetween are arranged coaxially on the crankshaft, and twelfth second and third pistons are respectively disposed on the twelfth second and third crank pins. The first and second cylinder blocks that are connected to each other and accommodate the first and second pistons are disposed substantially horizontally, while the third cylinder block that accommodates the third piston is connected to the first and second cylinder blocks. The first and second piston systems are arranged substantially vertically so as to have a bank angle of 90° between them, and the total reciprocating mass of the first and second piston systems is made substantially equal to the reciprocating mass of the third piston system. A three-cylinder internal combustion engine, wherein the crankshaft is provided with a balance weight that substantially balances the primary inertia force of the two-piston system and the primary inertia force of the third piston system.