JPS5947516A - Two-cycle 3-cylindered internal-combustion engine - Google Patents

Abstract

PURPOSE:To restrain vibration due to the primary inertial force by disposing cylinder blocks respectively including two steam cylinders and one steam cylinder in such a manner as to be V-shaped with a bank angle of 90 deg., and improving the shape of a balance weight mounted on the crankshaft. CONSTITUTION:Three crank pins 51-53 mounted on the same axis of a crankshaft 1 are accomodated in respective crank cases 121-123 disposed separately from each other, and pistons 131-133 are respectively connected to the pins 51- 53 through connecting rods 141-143. Cylinder blocks 161, 162 and another block are disposed in such a manner as to be V-shaped with a bank angle of 90 deg.. The outside diameter of the connecting rod 143 is made larger than those of the other connecting rods 141, 142 so that the total reciprocating mass of the first and second piston systems is substantially equal to the reciprocating mass of the third piston system. The axial length of the crank case 123 is made longer than those of the crank cases 121, 122. The thickness of the third balance weights 23, 23'3 is made thicker than those of the other balance weights 23, 23;23'1, 23'2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention eliminates vibrations due to -order inertia force.
Regarding a cycle type three-cylinder internal combustion engine.

Conventionally, a known example of a two-stroke, three-cylinder internal combustion engine in which vibrations due to primary inertia are removed is one in which three crank pins are arranged at an interval of 120 degrees above the crank angle. However, this has the disadvantage that an unbalanced couple is generated on the crankshaft due to the phase shift of the crankpin.

The object of the present invention is to provide a simple and effective engine that removes vibrations due to -order inertia force without generating such an unbalanced couple, and in order to achieve this object, The first
and a third crank pin occupying a position intermediate between the second crank pin and the second crank pin.
The first, second, and third crank pins are arranged coaxially with each other, and the first, second, and third crank pins are arranged in the first, second, and third crank pins spaced apart from each other in the crankcase. The first connecting rod is housed in the second and third crank chambers, respectively, and is connected to the second and third crank pins via the J, second and third connecting rods.
．． The second and third pistons are connected to each other, and the first and second cylinder blocks that accommodate the first and second pistons and the third cylinder block that accommodates the third piston are opened at a bank angle of 90 degrees. The outer diameter of the third connecting rod is set to the outer diameter of the other connecting rods 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. thicker (and the overall -order inertia force of the first and second piston systems and the third
The first one is approximately balanced with the primary inertia force of the piston system. 2nd and 3rd] (a shifter characterized in that a run weight is attached to the crankshaft in the first, second and third crank chambers).

By the way, as mentioned above, if the outer diameter of the small end of the third connecting rod is made larger than the outer diameter of the small end of the other connecting rods,
Since the effective volume of the third crank chamber is smaller than that of the other crank chambers, the primary compression ratio of the air-fuel mixture in the third crank chamber is larger than that of the other crank chambers.
This is undesirable because it causes a difference in the explosive force in the combustion chamber of each cylinder block.

Therefore, the next object of the present invention is to provide the engine in which the primary compression ratios in each of the crank chambers can be easily made equal.
It is also a feature of the present invention that the axial length of the crank chamber is longer than that of the other crank chambers, and that the third balance weight is thicker than the lance weight.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.In FIG.
crankshaft 1 and the output shaft 2 of the transmission driven by it
゜ is arranged parallel to the axles 3f and 3r of i'iil + rear wheel 1/'f, Fr, and the output shaft 20 drives the rear wheel Wr via the chain transmission 4, 3
As shown in the figure, the three-cylinder internal engine E is configured as a two-stroke type, and the three crank pinots of the crankshaft 1 are 5+, 52 . 53 are aligned on the same axis, and the crank pins 51.5□ at both left and right outer positions are aligned on the same axis.
And the second crank pin, the crank pin 53 at the center position is referred to as the third crank pin.

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

The crankshaft 1 is supported by a crankcase 11 via four bearings 1o, io, . The four bearings 10, 10... are connected to the three crank pins 5, . 52.53
The interior of the crankcase 11 is separated by partition walls that support these bearings.
Second. 3rd crank pin5. ．． 52, 53, respectively. 3rd crank chamber 12+, 122
; divided into 123 sections.

1st. Second. 3rd crank pin5. ．． 52.53 has the 1st. Second. Third piston 13. ．． 132.

133 is the first. Second. 3rd stove 14. , 142
゜143 and 1st. Second. 3rd piston pin 151゜1
52.153 via the 1st. Second. 3rd piston 13+
, 132. 133 are connected to each other, and these pistons 13. ．． 13□ and 133 slide together. Second
．． Third cylinder block 16. ．． 162° and 163 are fixed to the crankcase 11. At that time, the first and second
Cylinder blocks 16□, 16□ face the front of the vehicle (
Also, the third cylinder block 16. are arranged so as to face upward, and thus the first and second cylinder blocks 161, 162 and the third cylinder block 16
3 is arranged in a V-shape with a bank angle of 90 degrees.

Maki 1. Second. Third cylinder block 16. ．． 16□.

The outer periphery of the tip of 163 has the first. Second. A third cylinder head 17+, 172-17'3 is screwed onto the cylinder head 17. ．． Water jacket IL around 17□, 173, 182. 1st forming 183
．． Second. Third head cover 19. ．． 192°193 are installed. 1st. Second. Third cylinder head 171.
172. 173 has Uτ1. 2nd ° 3rd spark plug 20+
, 202. 203 are screwed on, and these spark plugs 20
□, 20□, 203 are the combustion chambers 21, . In order to cause simultaneous explosions at 212, an ignition (not shown) is set so as to provide a phase difference of 90 degrees at a crank angle between the timing of these explosions and the timing of explosion in the combustion chamber 213 in the third cylinder head 173. Controlled by a control device.

The reciprocating masses of the 13.degree. In order to satisfy such conditions, the outer diameter of the third connecting rod 143 is set to be the same as that of the first and second connecting rods 14. ．． 14□ small end 1
4. α is made larger than the outer diameter of 142α.

Even with this arrangement, if the reciprocating mass of the third piston 133 system is insufficient, as shown in FIGS. 2 and 3, the first and second piston pins 15. ．． 15□ is formed hollow, while the third piston pin 153 is preferably formed to have a larger diameter than the third piston pin 153 and to be solid.

Crankshaft 1 has three crank pins 5□, 5□.

5, each pair of first . Second. Third crank web 22+, 221'; 222, 22□
'; 223 and 223, and the first. Second. 3rd crank pin 5+
, 52. 53 and each pair of first .
Second. 3rd Balanne weight 23. ．． 23. ';23□
, 232'; 233, 233 are arranged in series, and these balance weights are such that the sum of the centrifugal force during their rotation is the same as that of the first and second pistons 13. ．． The primary inertia force of the 132 system and the primary inertia force of the third piston 133 system are approximately balanced, and the 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+Z23□, 23□'; 233.23° is the 2nd. 3rd crank pin 50,5□.

A mass equal to the rotating mass of the 53 series is added to balance the crankshaft 10 rotations.

Each cylinder block 16+ (the same goes for 16□, 163) has an intake boat 24 that communicates with the crank chamber 12 in the same row, and a combustion chamber 2 in the same row that connects the crank chamber 12°.
A pair of left and right scavenging boats 25.25 communicated with 11,
An exhaust port 28 is provided to communicate the combustion chamber 211 with an exhaust pipe 26 or 27 (see FIG. 1), and each intake port 24 is equipped with a reed valve 29 to prevent backflow of the air-fuel mixture. Each intake port 24 is connected to the first and second cylinder blocks 16 . ．． 162 and third cylinder block 163
The carburetor 31 and its air cleaner 32, which are installed in each intake port 24, are disposed in the space 30 so as to open into a V-shaped space 30 formed between the two.

Lock 16. Regarding the side, since the crank chamber 12□ is depressurized during the upward stroke of the piston 131, the carburetor 31
The air-fuel mixture generated in the intake port 24 and the reed valve 29
Through the crank chamber 12. The piston 131
Since the crank chamber 121 is pressurized during the downward stroke of the piston 13 , the air-fuel mixture pressurized here is filled into the combustion chamber 211 through the scavenging bows 25 , , 25 , and the piston 13 . After being compressed during the upward stroke of the spark plug 20. The piston 13 is ignited by the discharge and burns (explodes). A descending force is applied to the piston 131, and the exhaust boat 2 opens during the downward movement of the piston 131, and then the combustion chamber 21. of exhaust gas will be emitted.

A similar operation is performed on the second and third cylinder blocks 162 and 163.

During this time, Balance Way 1-23. ．． 23. ';2
3□, 232'; 23s - 233 group is the first and second cylinder block 16. ．． 16□, their centrifugal force is applied to the first and second pistons 13. , 13□ system, and when the balance weight group is on the vertical plane including the center line of the third cylinder block 163, their centrifugal force is the first-order inertia force of the third piston 13° system. Balance the inertial force.

Also, first and second pistons 13, . 1
The resultant force of the primary inertial force of system 32 acts on the center of the crankshaft 1, and the primary inertial force of the third piston 133 located at the center also acts on the center of crankshaft 1, and the point of action is always stationary. Yes, on the other hand, balance weight 23□,
23. ';23□.

232'; 233. Since the mass distribution of the crankshafts 233 is symmetrical, the centrifugal force caused by them is also concentrated at the point of action, and as a result, no force couple is generated on the crankshaft 1.

1st. the second cylinder block 16. ．． 162゜1
At 63, the pistons 13+, 132, 13
3 stroke volume and combustion chamber 21. ．． If the compression ratios of 212 and 213 are equal, then the crank chamber 12+
, 122. 12a have different compression ratios, the combustion chamber 21. ．． 212. This is not desirable as it causes a difference in the explosive power of the mixture at 213. However, as mentioned above, the first
and a second piston 131.

In order to equalize the total reciprocating mass of the 13□ system and the reciprocating mass of the third piston 133 system, the piston pin 153 and connecting rod small end 143a of the third piston 133 system 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 12. ．． 12
Since the primary compression ratio of the air-fuel mixture in the third crank chamber 123 is smaller than that of the other crank chambers 12. ．． It will be larger than that of 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 and 122 (and the third crank chamber 123 is The overall thickness of balance weight 233゜233 is that of other balance weights 231゜23,';23□,23
□' is thicker than each total thickness (and thereby the third crank chamber 12. and the third balance way) 233. 233
Which interstitial volume is the other crank chamber 12. ．． 12. and other balance weights23. ．． 23゜';232.232'
It is thicker than each gap volume.

In this case, in order to make the width of engine E as short as possible,
and second crank web 22+-2L'; 22□, 2
22' at each inner web 22. ．． 222' on each outer web 22. , 22□ is effective. That is, in this way, the inner webs 221', 22
□′ is thinner. Second cylinder block 16
The distance between 1,162 and 1,162 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. ．． 52 is attached to the thick outer web 22. ．． Press-fitting into the 22□ coupling holes 331 and 332 provides a sufficient press-fitting depth, and is effective in obtaining an assembled crankshaft 1 with a high crankpin coupling strength.

As described above, according to the present invention, the first and second crank pins and the third crank pin occupying an intermediate position are provided on the crankshaft supported by the crankcase so as to be coaxially aligned, and the first and second crank pins are arranged coaxially. The second and third crank pins are separated from each other in the crankcase.
are housed in the second and third crank chambers respectively, and these first
．． 1st to 2nd and 3rd crank pins. The first through the second and third connecting rods. The second and third pistons are connected to each other, and the first and second cylinder blocks that accommodate the first and second pistons and the third cylinder block that accommodates the third piston are opened at a bank angle of 90 degrees. TeV
The first and second piston systems are arranged in a shape such that the total reciprocating mass of the first and second piston systems is approximately equal to the reciprocating mass of the third piston system, and the total -order inertia of the first and second piston systems is equal to the total reciprocating mass of the third piston system. A balance weight that approximately balances the primary inertia force of the three-piston system is provided in the first. Since it is provided on the crankshaft in the second and third crank chambers, the primary inertial force of the first and second piston systems and the primary inertial force of the third piston system can be respectively balanced using a common balance weight, It is possible to eliminate engine vibrations caused by -order inertial force.

Further, in order to make the total reciprocating mass of the first and second piston systems substantially equal to the reciprocating mass of the third piston system,
The outer diameter of the small end of the third connecting rod is made thicker than the outer diameter of the small ends of the other connecting rods, so it is easy to balance the desired reciprocating mass by simply changing the shape of the small end of the third connecting rod. You can get it.

In addition, since the point of action of the resultant force of the primary inertial force of the entire piston system is always at one point in the center of the crankshaft and does not change, the centrifugal force of the balance weight can be concentrated on the one point, which It is possible to prevent the occurrence of an unbalanced couple, and also to avoid engine vibration caused by an unbalanced couple, and the structure is not particularly complicated compared to a conventional three-cylinder internal combustion engine. .

Furthermore, since the axial length of the third crank chamber is made longer than that of the other crank chambers, and the thickness of the third balance weight is made thicker than the thickness of the other balance weights, each crank chamber and the balance weight are While keeping any radial clearance constant, the gap between the third crank chamber and the third balance weight can be made larger than the gap volume between the other crank chambers and the other balance weights, thereby increasing the volume of the third connecting rod. It is possible to correct the difference in the primary compression ratio of the air-fuel mixture in each crank chamber due to the enlargement of the outer diameter of the small end, and the radial gap between each crank chamber and the balance weight can be kept constant. This is very advantageous in terms of processing and dimensional control.

In addition, in the present invention, the reciprocating mass '++Irl of the first and second piston systems, and the reciprocating mass 1173 of the third piston system
Making them substantially equal includes the case where -4-l112 and lV3 are close to each other within an allowable range for vibration prevention. Specifically, Ir3 is F, -4 -V12(7')75~I] As long as it falls within the range of 0%, there is actually no difference.

[Brief explanation of drawings]

Fig. 1 is a side view of a motorcycle equipped with a two-stroke, three-cylinder internal combustion engine according to an embodiment of the present invention, Fig. 2 is a longitudinal sectional plan view of the main parts of the engine, and Fig. 3 is II of Fig. 2. -I
It is a sectional view taken along line II. E... Three-cylinder internal combustion engine, 1... Crankshaft, 5. ~
53... First to third crank pins, 11... Crank case, 12. ~123...first to third crank chambers, 13,~133...first to third pistons, 14. ~
143...1st to 3rd conrod, 14□a, 14□
a. 143α...small end portion, 15, to 153... first to third piston pin, 161 to 163... first to third cylinder block, 22. ．． 22. ';222.222';
223, '223... 1st. Second. Third crank web, 23+, 23+'; 232. 23□';2
33,233...1st. Second. 3rd Balance Weight Patent Applicant Honda Motor Co., Ltd. Representative Patent Attorney Renichi Ochiai Tomoe! ” Procedural Amendment (Method) 1982 (V, April-5L) 1. Indication of the case 1983 Patent Application No. 183839 2. Name of the invention 2-cycle three-cylinder internal combustion engine 3. Case of the person making the amendment Relationship with Patent applicant name (532) Honda Motor Co., Ltd. 4th generation
Mr. Hito 105 Telephone Tokyo 434-4151 5. Date of amendment order: March 9, 1982 (Shipping date: March 29, 1988)
6 All drawings subject to correction

Claims (1)

[Claims] The first and second
The crank pin and the third crank pin occupying an intermediate position between these should be aligned on the same axis, and these first crank pins should be aligned on the same axis.
．． Second and third crank bins are housed in third, second and third crank chambers separated from each other within the crankcase, respectively, and these first and third crank bins are housed in third, second and third crank chambers separated from each other within the crankcase. The first and second crankshafts are connected to the second and third crankbins via the second and third connecting rods. The second and third pistons are connected to each other, and the first and second cylinder blocks that accommodate the first and second pistons and the third cylinder block that accommodates the third piston are opened to a bank angle of 9 degrees. arranged in a V-shape, the first and second
The outer diameter of the third connecting rod is made larger than the outer diameter of the other connecting rods so that the total reciprocating mass of the piston system and the reciprocating mass of the third piston system are approximately equal. First, second and third balance weights are attached to the crankshaft in the first, second and third crank chambers to substantially balance the total inertial force of the first order inertia and the first order inertia of the third piston system, respectively. and a two-cycle type three-cycle engine, in which the axial length of the third crank chamber is equal to the length of the other crank chambers (and the thickness of the third balance weight is thicker than that of the other balance weights). Cylinder internal combustion engine.