JPS6335858B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a three-cylinder internal combustion engine in which three cylinders are arranged in series, while maintaining the balance between the reciprocating motion part and the rotational motion part of each cylinder. , relates to technology that aims to reduce size and weight.

[Conventional technology and its problems]

Japanese Patent Publication No. 51-7242, which is a prior art for balancing an in-line three-cylinder internal combustion engine, sets the phase of each cylinder at an interval of 180 degrees in terms of crank angle, and also sets the reciprocating motion part between the first and third cylinders. The mass of the reciprocating part and the mass of the rotating part in the second cylinder located in the middle are the same as that of the reciprocating part of the other cylinder, that is, the first cylinder or the third cylinder. It is proposed to make the mass approximately twice the mass of the rotating part. If you do this, the second cylinder will be a regular inline 4
This corresponds to combining the second cylinder and third cylinder in a cylinder internal combustion engine into one cylinder, and has substantially the same balance state as an in-line four-cylinder internal combustion engine.

However, in order to make the mass of the reciprocating motion part and the mass of the rotary motion part in the second cylinder approximately twice the mass of the reciprocating motion part and the rotary motion part in the other cylinders, it is necessary to Since the mass of the large end of the connecting rod must be approximately twice the mass of the large end of the connecting rod in the other cylinders, the large end of the connecting rod in the second cylinder is large and can accommodate this. Not only does the crankcase and therefore the engine become larger, but the connecting rods for each cylinder cannot be made into a common part.

Therefore, Japanese Patent Application Laid-Open No. 56-131852 discloses that in an in-line three-cylinder internal combustion engine in which the phase between adjacent cylinders is 180°, the mass of the reciprocating part in the second cylinder is calculated as the mass of the reciprocating part in the other cylinders. Abbreviation 2
On the other hand, by providing a balance weight for the rotational movement part of the first or third cylinder on the crank arm of the first and third cylinders at a phase position of 180 degrees from the crank pin, the second cylinder It is proposed to avoid increasing the size of the large end of the connecting rod in the engine, to make the connecting rod common to each cylinder, and to downsize the crankcase and eventually the engine.

However, in an in-line three-cylinder internal combustion engine, the crankshaft is located between the first cylinder's crank arm and the second cylinder's crank arm, between the second cylinder's crank arm and the third cylinder's crank arm, and between the first cylinder's crank arm and the third cylinder's crank arm. Journal parts are provided at four locations: the outer end of the crank arm and the outer end of the third cylinder crank arm,
While the cylinder is supported by these four journal parts, the reciprocating motion of the first and third cylinders and the reciprocating motion of the second cylinder are shifted in phase by 180 degrees, so that one is forward. During the stroke, the other moves in opposite directions, so the first
A large shear force is applied to the journal between the cylinder and the second cylinder and the journal between the second and third cylinders due to the reciprocating motion of both cylinders in opposite directions on both sides of the journal. will come into play.

Therefore, these two journal parts must be configured to have a considerably large diameter in order to sufficiently withstand this large shearing force, which not only makes the engine large and heavy, but also causes the bearings of both journal parts to have a large diameter due to the shearing force. There was a problem of reduced durability due to uneven wear.

In an in-line three-cylinder internal combustion engine, the present invention provides a journal portion between a first cylinder crank arm and a second cylinder crank arm, and a third cylinder crank arm in a balanced state. The purpose of this is to reduce the shearing force generated in the journal between the cylinder and the crank arm of the second cylinder.

[Means for solving problems]

In order to achieve this objective, the present invention has developed a system for adjusting the phase of three cylinders arranged in series with a common crankshaft.
180°, while the masses of the reciprocating parts and the masses of the rotary parts in the first and third cylinders located on both sides of the central second cylinder are made approximately the same for both cylinders, and the second cylinder is The mass of the reciprocating part in the cylinder is approximately twice the mass of the reciprocating part in the first cylinder or the third cylinder, and the crankshaft is arranged between the first cylinder and the second cylinder and between the second cylinder and the second cylinder. In a three-cylinder internal combustion engine, each of which is pivotally supported between a cylinder and a third cylinder, the first
The outer crank arm of each pair of crank arms in the cylinder and the third cylinder has a balance at a phase position of 180° from the crank pin in each cylinder, which balances the rotational movement part in the first cylinder and the third cylinder. While each weight is provided, the crank arm located on the inside of each pair of crank arms in the first cylinder and the third cylinder is provided with a weight from the crank pin in each of the crank arms.
At a phase position of 180°, overbalance weights having an appropriate balance ratio relative to the masses of the reciprocating parts in the first cylinder and the third cylinder are provided, and further,
The pair of crank arms in the second cylinder are each provided with an overbalance weight that balances the overbalance weights in the first and third cylinders at a phase position of 180 degrees from the crank pin.

[Effect]

In this way, by providing the crank arms of the first and third cylinders with balance weights that balance the rotational motion of the first and third cylinders, the rotational motion of the first and third cylinders is reduced. Since the balance can be maintained by the balance weights provided in each of the first and third cylinders, it is possible to balance the rotational motion without increasing the mass of the rotary motion part in the second cylinder. can.

External forces due to the reciprocating motion of the reciprocating portions of the first and third cylinders are applied to both journal portions of the crankshaft between the first and second cylinders and between the second and third cylinders. acts in a direction perpendicular to the crank axis, but overbalance weights are applied to the crank arms of the first and third cylinders at appropriate balance rates relative to the masses of the reciprocating parts of the first and third cylinders. By providing this, the external force caused by the rotation of both overbalance weights is applied to both journal parts.
Since the external force due to the reciprocating motion of the reciprocating portion acts in the opposite direction, the first
It is possible to reduce the shearing force generated by the reciprocating motion of the reciprocating parts in the cylinder and the third cylinder.

Further, by providing the pair of crank arms in the second cylinder with an overbalance weight that balances the overbalance weight in each of the first cylinder and third cylinder, the above-mentioned This makes it possible to eliminate the unbalance of rotational motion caused by providing an overbalance weight.

〔Example〕

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
This shows a three-cylinder engine in which the first and second cylinders are arranged in series at equal intervals in the axial direction of the crankshaft 5.
Outside of cylinder 1, between first cylinder 1 and second cylinder 2,
Between the second cylinder 2 and the third cylinder 3, and the third cylinder 3
There are journal parts 51, 52, 5 at four locations on the outside of the
3 and 54, respectively, and these four journal parts 5
1, 52, 53, and 54 are pivotally supported by a cylinder block (not shown) or a crank case (not shown), etc. via bearings 61, 62, 63, and 64, and each of the above-mentioned Crank arm pairs 11, 11', 21,
21'31, 31' are integrally provided, and the crank arm pair 11, 11' and the third crank arm pair in the first cylinder are integrally provided.
In the crank arm pair 31, 31' in the cylinder,
Crank pins 12, 32 are located at an appropriate radius r ₁ from the axis of the crankshaft 5, and crank pins ₂₂ are installed at an appropriate radius r 2 from the axis of the crankshaft 5 on the crank arm pair 21, 21' in the second cylinder. are each provided integrally.

Also, in each cylinder, the piston pin 14,
Piston 13, 23, 33 with 24, 34
are connected to the respective crank pins 12, 22, 32 via connecting rods 15, 25, 35, respectively. In this case, the crank pin 12 in the first cylinder 1 and the crank pin 32 in the third cylinder 3 are in the same phase position with respect to the rotation angle of the crankshaft 5, but the crank pin 22 in the second cylinder 2 is in the same phase position with respect to the rotation angle of the crankshaft 5. It is arranged at a phase position of 180 degrees with respect to the other cylinders, that is, the crank pin 12 of the first cylinder and the crank pin 32 of the third cylinder. That is, each cylinder is configured such that the phase between adjacent cylinders is 180°.

The mass of the reciprocating part of each cylinder in this three-cylinder engine is the mass _M1 of the reciprocating part of the first cylinder 1 (the smaller end of the mass of the piston 13, the mass of the piston pin 14, and the mass of the connecting rod 15). mass of the reciprocating part in the third cylinder 3 (the mass of the piston ₃₃ , the mass of the piston pin 34, and the mass of the connecting rod 35 that acts on its small end) The mass M ₂ of the reciprocating part in the second cylinder 2 (the sum of the piston 23, the piston pin 24, and the mass of the connecting rod 25) is made equal or approximately equal. Balance is achieved by making the total mass of the reciprocating portion of the first cylinder 1 twice or approximately twice the mass M ₁ of the reciprocating portion of the first cylinder 1 or the mass M ₃ of the reciprocating portion of the third cylinder 3.

In addition, with respect to the mass of the rotational movement part for each cylinder, the outer crank arm 11 of the crank arm pair 11, 11' in the first cylinder 1,
and a crank arm pair 31 in the third cylinder 3,
Balance weights 71, 73 for the mass of the rotary moving part of the first cylinder 1 or the third cylinder 3 are mounted on the outer crank arm 31 of the crank arm 31' at a phase position of 180 degrees with respect to the respective crank pins 12, 32.
Balance is achieved by providing .

That is, the mass of the rotating parts in the first cylinder 1 (the mass of the crank pin 12, the mass of the crank arms 11 and 11' that acts on the 12 crank pins, and the mass of the connecting rod 15 at its large end) ) and the total mass acting on the third cylinder 3
The mass of the rotating part (crank pin 32
m ₁ , m ₃ , The mass of the rotational movement part in the second cylinder 2 (the mass of the crank pin 24,
The sum of the mass of the crank arms 21, 21' that acts on the crank pin 24, and the mass of the connecting rod 25 that acts on its large end)
m ₂ , the masses of the balance weights 71 and 73 are m _w1 and m _w3 respectively, and the radius from the center of the crankshaft 5 to the center of gravity of the balance weights 71 and 73 is
r _w , in order to maintain the balance, m ₁ r ₁ + m ₃ r ₁ = m ₂ r ₂ + 2m _w r _w (however, m _w1 = m _w3 =
m _w ) holds true, and here we set r ₁ = r _w , that is,
The center of gravity of both balance weights 71 and 73 is the first
If it is installed at a radius dimension equal to the crank radius r ₁ of cylinder 1 or third cylinder 3, the mass m _w of both balance weights 71 and 73 is m _w = m ₁ -1/2 m ₂ r ₁ /r ₂ , and the rotating mass is balanced.

The inner crank arm 11' of the crank arm pair 11, 11' in the first cylinder 1,
and a crank arm pair 31 in the third cylinder 3,
The inner crank arm 31' at 31' has a
The two journal parts 52 and 5 are moved to a phase position of 180 degrees from the respective crank pins 12 and 32 by the reciprocating motion of the reciprocating parts of the first cylinder 1 and the third cylinder 3.
Overbalance weights 81 and 83 are provided to reduce the shear force acting on each of 3.
Both crank arms 21, 2 in the second cylinder 2
1', both overbalance weights 81, 8 are placed at a phase position of 180° from the crank pin 22.
an overbalance weight 82 balanced against 3;
82' are provided respectively.

That is, the journal portion 52 of the crankshaft 5 is caused to reciprocate at an angular velocity r ₁ ω ² of the reciprocating parts such as the piston 13 in the first cylinder.
An external force of M ₁ r ₁ ω ² acts as a shearing force in the direction perpendicular to the axis of the crankshaft 5, and similarly, M An external force of ₃ r ₁ ω ² acts on the crankshaft 5 as a shearing force in a direction perpendicular to the axis, but the inner crank arm 11' of the first cylinder 1 and the inner crank arm 31' of the third cylinder 3 When overbalance weights 81 and 83 are respectively provided at a phase position of 180 degrees from the respective crank pins 12 and 32, m ₀ r ₀ is generated in both journal parts 52 and 53 due to the rotation of each overbalance weight 81 and 83. External force of ω ² (however, m ₀₁ and m ₀₃ are each overbalance 81, 83
mass, r ₀ is each overbalance weight 81,8
3) is perpendicular to the axis of the crankshaft 5 and acts in the opposite direction to the external forces of M ₁ r ₁ ω ² and M ₃ r ₁ ω ² , so the M ₁ r ₁ ω ² and M ₃ The shear force due to the external force of r ₁ ω ² is applied to each overbalance weight 8
It can be reduced by 1.83.

In this case, from the center line of the second cylinder 2 to the first cylinder 1
and the distance to the center of the third cylinder are respectively l ₁ ,
l ₃ The distance from the center line of the second cylinder 2 to the center of gravity of each overbalance weight 81, 83 is l ₀₁ and l ₀₃ respectively.
Then, since l ₁ = l ₃ and l ₀₁ = l ₀₃ = l ₀ , M ₁ r ₁ ω ² l ₁ = m ₀ r ₀ l ₀ or M ₃ r ₁ ω ² l ₁ = m ₀ r ₀ The relationship l ₀ is established, and from this, the mass m ₀ of each overbalance weight 81, 83 is m ₀ = M ₁ l ₁ / l ₀ or m ₀ = M ₃ l ₁ / l ₀ (however, M ₁ = M ₃ ).

In this way, overbalance weights 81, 83
Since the shear force acting on both journal parts 52, 53 is reduced by providing both journal parts 52, 53,
The shaft diameter of 53 can be reduced accordingly, and a bearing 62, which pivotally supports both journal parts 52, 53, is provided.
63 is also made smaller, which in turn allows the engine to be made smaller and lighter.Furthermore, the wear on one side of the bearings 62, 63 of both journal parts 52, 53 is reduced, increasing durability.

In addition, overbalance weights 81 are attached to the crank arms of the first cylinder 1 and the third cylinder 3 in this way.
By providing 83, the balance with respect to rotational motion becomes unbalanced. Therefore, the unbalance due to both overbalance weights 81 and 83 is also caused by both crank arms 21 and 21' in the second cylinder 2. From pin 22
Balance is achieved by providing overbalance weights 82, 82 having the same mass as the two overbalance weights 81, 83 at a phase position of 180°.

In the above formula, is called the balance rate, and as is clear from the formula, it is considered that it is sufficient to set the balance rate to 1, but setting the balance rate to 1 means that the first cylinder 1 and the third cylinder 3 both overbalance weights 81, 83, and both overbalance weights 82, which were also provided in the second cylinder 2 to balance the two overbalance weights 81, 83.
A total of 4 overbalance weights with 82',
The mass must be approximately the same as that of the reciprocating parts of the first cylinder or the third cylinder, respectively, which would result in a significant increase in the weight of the engine.
In order to reduce the size and weight of the engine by reducing the shear force at 2 and 53, the balance ratio is preferably 0.5 or less.

In addition, as described above, the crankshaft 5 is provided with balance weights 71 and 73, and an overbalance weight 8.
1, 83 and 82, 82', the force couple generated on the crankshaft by the rotation of these balance weights is made equal on both the left and right sides of the center line of the second cylinder 2, that is, m _w l _w1 +m ₀₁ l ₀₁ −
m ₀₂ l ₂ = m _w l _w3 + m ₀₃ l ₀₃ −m ₀₂ l ₂ (However, l _w1 and l _w3 are the balance weights 71, 7 from the center of the second cylinder 2.
3, m ₀₂ is the mass of the overbalance weights 82, 82' in the second cylinder 2, l ₂
is the distance from the center of the second cylinder 2 to its overbalance weights 82 and 82').
The weights 82 and 82' must be adjusted so that their masses and distances from the second cylinder are equal to each other. is extremely complex and difficult. In contrast, in the present invention, both balance weights 71 and 73, which are the heaviest of each weight, are connected to the outer crank arms 11 and 73 of the first cylinder 1 and the third cylinder 3.
13, and the distance from the second cylinder 2 is the farthest position, while both balance weights 71,
73 and the mass for an appropriate adjustment allowance, and then shave off both balance weights 71 and 73 by appropriate means such as one or more adjustment holes drilled in each of them to obtain the values on both sides of the above equation. In this case, both balance weights 71 and 73 are farthest from the center line of the second cylinder 2, and both balance weights 71 and 73 are
The amount of removal of 1,73 has a large effect on the values on both sides of the above equation.In other words, the values on both sides of the above equation are smaller than when the overbalance weights 81, 83 and/or 82, 82' are removed. Since the values on both sides change greatly, it is possible to adjust the values on both sides to be equal by only removing a small amount from both balance weights 71 and 73. Correspondence adjustment between 82 and 82' becomes unnecessary.

〔Effect of the invention〕

In summary, the present invention has the structure described in the claims, and the reciprocating motion part and the rotational motion part of each cylinder are balanced, and the crankshaft is able to maintain the balance between the two journal parts between each cylinder. Shearing force can be reduced, and by reducing the diameter of both journal parts, the engine can be made smaller and lighter, and it is possible to reduce uneven wear of the bearings in both journal parts, improving durability. Furthermore, when providing balance weights and overbalance weights to the crank arms of the first and third cylinders, the present invention provides balance weights to the outer crank arms of each pair of crank arms of the first and third cylinders. By separately providing the overbalance weight on the inner crank arm, the balance weight and overbalance weight for one cylinder are integrated, which increases the overall balance weight, and as a result, the crank This makes it possible to avoid having to make the case larger.

[Brief explanation of the drawing]

FIG. 1 is an arrangement diagram of a three-cylinder internal combustion engine according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of FIG. FIG. 1...1st cylinder, 2...2nd cylinder, 3...3rd cylinder
Cylinder, 5... Crankshaft, 11, 11', 21,
21', 31, 31'... crank arm, 12,
22, 32...Crank pin, 51, 52, 5
3, 54... Journal part, 61, 62, 63,
64... Bearing, 71, 73... Balance weight, 81, 83, 82, 82'... Over balance weight.

Claims (1)

[Claims] 1 The phase of three cylinders arranged in series with a common crankshaft is 180°, while the first and third cylinders are located on both sides of the second cylinder in the center.
The mass of the reciprocating part and the mass of the rotary part in the cylinder are made substantially the same for both cylinders, and the second
The mass of the reciprocating part in the cylinder is approximately twice the mass of the reciprocating part in the first cylinder or the third cylinder, and the crankshaft is arranged between the first cylinder and the second cylinder and between the second cylinder and the second cylinder. In a three-cylinder internal combustion engine, each of which is pivotally supported between a cylinder and a third cylinder, the crank arm located on the outside of each pair of crank arms in the first cylinder and the third cylinder has a crank arm in each pair. From the pin
A balance weight is provided at a phase position of 180 degrees to balance the rotational movement portion in the first cylinder and the third cylinder, while a crank arm located inside of each pair of crank arms in the first cylinder and the third cylinder. , an overbalance weight having an appropriate balance ratio relative to the mass of the reciprocating portion in the first cylinder and the third cylinder is provided at a phase position of 180 degrees from the crank pin in each of them, and A three-cylinder internal combustion engine characterized in that each of the pair of crank arms is provided with an overbalance weight that balances the overbalance weight in the first cylinder and the third cylinder at a phase position of 180 degrees from the crank pin. .