JP2001020937A - Internal combustion engine having irregular journal diameter crankshaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce frictional loss of a journal part while holding strength of a crankshaft by differing each diameter of journals from one another according to a difference of twist torques acted on a plurality of journals. SOLUTION: When a cylinder which is nearest to a timing belt of an in-line four-cylinder type gasoline engine is set as the first, a cylinder which is nearest to an output shaft is set as the fourth, and the maximum value of twist torques acted on journals 1J to 5J are set as T1max to T5max; there is a relation of T2max>T3max>T4max>T5max>T1max. On the basis of the difference of those torques, a second journal diameter D2 is set to the maximum value, a first journal diameter D1 is set to the minimum value, the rest of the journal diameters are set to the intermediate value between the diameters D2 and D1. Preferably, it is set to D2>D3>=D4>=D5>D1. Frictional loss generated at the journal parts can be reduced by contracting the journal diameters, and thereby, the frictional loss of the whole engine is largely reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an internal combustion engine,
In particular, the present invention relates to an internal combustion engine in which the diameters of a plurality of journals of a crankshaft are set to non-uniform diameters.

[0002]

2. Description of the Related Art FIG.
2 shows a crankshaft of a cylinder engine. As shown, five crank journals 1J to 5J are provided such that the crank journals are located on both sides of each cylinder. All journals have the same diameter. This diameter is set to the size required by the heaviest loaded journal.

In addition, the first journal 1J and the first pin 1P
The oil supply hole penetrates between the two. Using this oil supply hole, oil supply to the first pin 1P, that is, oil supply to the connecting rod of the first cylinder is performed. Similarly, from the second journal 2J to the second pin 2P, the fourth journal 4J to the third pin 3P,
An oil supply hole extends from the fifth journal 5J to the fourth pin 4P. No oil hole is provided in the third journal 3J.

In Japanese Patent Application Laid-Open No. 9-269004, the journal diameter of the crankshaft is set to a non-uniform diameter. The journal diameter is set to increase from the first journal to the fifth journal. With this setting, the natural frequency of the crankshaft is increased to increase the dynamic rigidity.

[0005]

By the way, there has been a demand for minimizing the friction loss of the internal combustion engine as much as possible for the purpose of improving fuel efficiency. A factor that largely affects friction loss is a journal diameter of a crankshaft. Therefore, it is desirable to reduce the journal diameter as much as possible to reduce the friction loss. However, when the journal diameter is reduced, there is a problem that the strength of the crankshaft decreases.

[0006] When the internal combustion engine is in a high rotation state, the state of oil supply to the crankpin, that is, the state of oil supply to the connecting rod bearing, deteriorates. One of the causes is a centrifugal force acting on the oil at the crank journal. Under high rotation, the centrifugal force acting on the oil supplied from the cylinder block to the crank journal increases. Therefore, the amount of oil supplied from the crank journal to the crankpin through the oil supply hole is reduced.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an internal combustion engine that can reduce the friction loss of a journal while sufficiently maintaining the strength of a crankshaft.

A further object of the present invention is to provide an internal combustion engine capable of improving the lubrication state of a connecting rod bearing under high rotation.

[0009]

(1) To achieve the above object, the present invention relates to an internal combustion engine having a crankshaft having a plurality of journals, wherein a difference between a combustion explosion torque and a journal torsion torque based on a loss torque is provided. In response to the,
The journal diameters of the plurality of journals are set differently.

According to the present invention, utilizing the fact that the torsional torque acting on the journal differs for each journal,
Set the diameter of the journal according to the torsional torque. That is, the diameter of the journal having a small torsion torque is reduced. Thus, the journal diameter can be reduced while maintaining the strength of the crankshaft, and the friction loss generated in the journal portion can be reduced. And the friction loss of the whole internal combustion engine can be reduced, and the fuel efficiency can be improved. Further, the weight of the internal combustion engine can be reduced by reducing the diameter of the journal.

For example, the internal combustion engine is an in-line n-cylinder type, the journal on the opposite side to the output shaft is the first journal, and the journal closest to the output shaft is the n + 1th journal.
At this time, the torsional torque acting on the crank journal is as follows: No. 2> No. 3> No. 4>. That is, the torsional torque is the largest in the second journal, and decreases as going to the third, fourth,.
The torsion torque of the No. 1 journal is the minimum. Based on such a difference in torque, it is preferable that the diameter of the second journal is maximized and the diameter of the first journal is minimized.

In the present invention, the diameters of all the journals may be set differently. For example, the journal diameter is set so that the stress generated by the torsional torque is substantially constant in all the journals. However, not all journals have different diameters, but some journals may have the same diameter. Specifically, No. 2> No. 3> No. 4
.. It is considered that the setting such as n.gtoreq.n + 1> 1 is appropriate.

(2) In a preferred embodiment of the present invention, the journal diameter of the third journal is set smaller than that of the second journal, and the lubrication hole for the second clamp pin between the second journal and the third journal is 3 Numbered journal. Refueling of other crankpins is also performed from the journal reduced in diameter according to the present invention.

As described above, in the present invention, the third journal diameter is set smaller than the second journal diameter based on the difference in the journal torsional torque. And conventionally, 2
Unlike refueling from pin # 2 to pin # 2,
In the present invention, oil is supplied from the third journal to the second pin.

Therefore, according to the present invention, lubrication from the small diameter journal to the crankpin is performed. Since the journal diameter is small, the centrifugal force acting on the oil in the journal portion is small. Especially at high rotation, the centrifugal force is significantly reduced. The decrease in the centrifugal force makes it easier for oil to enter the oil supply hole from the journal to the crankpin. Further, since the journal diameter is small, the amount of oil leaking from the end of the journal gap is reduced. As described above, the amount of lubrication to the crankpin can be increased, and the lubrication state can be improved.

According to the present invention, the load on the connecting rod bearing can be reduced by improving the lubrication condition. further,
It is also possible to increase the rotation speed of the internal combustion engine and reduce the size of the oil supply pump.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings.

FIG. 2 shows the internal combustion engine of the present embodiment. FIG. 2 shows only the crankshaft 1 and its peripheral portion in a simplified manner. An output shaft is attached to one end of the engine, and a timing belt is provided at the other end.

This internal combustion engine is an in-line four-cylinder gasoline engine, in which four cylinders are arranged at equal intervals. The cylinder closest to the timing belt is numbered 1, and the cylinder closest to the output shaft is numbered 4.

The crankshaft 1 has five journals 1J to 5J and four crank pins 1P to 4P, which are arranged alternately. The journal and the crankpin are connected by a web 4 with a counterweight.

The five journals 1J to 5J are arranged between adjacent cylinders and outside the first and fourth cylinders. The journal furthest from the output shaft, that is, the journal on the timing belt side is defined as the first journal 1J.
Thereafter, the journal number increases as approaching the output shaft. That is, the second journal 2J is between the first and second cylinders, and the third journal 3J is between the second and third cylinders.
The fourth journal 4J is arranged between the third and fourth cylinders, and the fifth journal 5J is arranged on the output shaft side of the fourth cylinder. The journal diameters (diameters) of the journals J1 to J5 are D1 to D5.

The five journals 1J to 5J are supported by the cylinder block 3. Specifically, a journal bearing is incorporated into a hole (housing) formed by the block body 3a and the cap 3b of the cylinder block 3, and the journal is supported by this bearing.

The four crank pins 1P to 4P are located at the centers of the first to fourth cylinders, respectively. A connecting rod 5 is attached to each crank pin. Connecting rod bearing 5 attached to the hole on the large end side of connecting rod 5
a is in contact with the crankpin. A piston is attached to the small end of the connecting rod 5 (not shown).

At the end of the first journal 1J, an oil pump mounting portion 7, a timing belt pulley mounting portion 9
And a crank pulley mounting portion 11 are sequentially provided. On the other hand, a flange 13 for attaching an output shaft is provided at the end of the fifth journal 5J. The flange portion 13 is connected to a transmission via a clutch or a torque converter.

[Setting of Journal Diameter] Next, features of the present embodiment will be described. In the present embodiment, the diameters of the five journals are set differently according to the difference in the torsional torque acting on the five journals.

The maximum value of the torsional torque acting on the five journals 1J to 5J is defined as T1max to T5max.
At this time, T2max>T3max>T4max> T5
There is a relation of max> T1max. That is, the largest torque is applied to the second journal, and the torque decreases in the order of the third, fourth, and fifth journals. The torque of the first journal is smaller than that of the fifth journal and is the minimum.

Based on such a difference in torque, the diameter of the journal on which a large torque acts is set large, and the diameter of the journal on which a small torque acts is set small. That is, the second journal diameter D2 is set to the maximum and the first journal diameter D1 is set to the minimum. The remaining journal diameter may be between D2 and D1. Preferably, D2
The fourth journal diameter is set to be equal to or smaller than the third journal diameter such that> D3 ≧ D4 ≧ D5> D1 (D5 = D1 may be used).

In the example of FIG. 2, the diameters of the third, fourth and fifth journals are set to be the same (D2> D3 = D4 = D5).
> D1). By making these journal diameters the same, machining of the crankshaft and cylinder block is facilitated.

The housing diameter of the cylinder block 3 is set differently in accordance with the journal diameter. Each housing diameter is the diameter of the corresponding journal, 2 times the bearing thickness.
It is a value obtained by adding double.

The setting of the journal diameter will be described in more detail. Let the transmission torque of the journal be Ti (i
Is the journal number). The torque generated by the combustion explosion is Tbj, and the loss torque of each cylinder is Tlj
(J is the cylinder number). The loss torque is a torque resulting from friction, inertia, gas compression, intake / exhaust work, and the like. The transmission torque of the i-th journal at the time of combustion explosion of the j-th cylinder is expressed as follows. From this equation, it is derived that the transmission torque T2 of the second journal is maximum and the transmission torque T1 of the first journal is minimum.

[0031]

(Equation 1) FIG. 3 shows an example of the calculation result of the torsional moment of each journal in a four-cylinder engine. The horizontal axis is the crank rotation angle, and the vertical axis is the moment. From FIG.
It can be seen that the maximum value of the torque decreases in the order of the second, third, fourth and fifth journals. Although the first journal is not shown in the drawing, a relatively small torque acts on the first journal for driving the accessory belt and the like, so the torque value is appropriately set. The torque acting on the journal may be determined by experiment or simulation.

Here, the maximum shear stress τmax acting on the journal is expressed as follows using the torsional moment Mz. r is the journal radius, Iz is the second moment of area pole, and D is the journal diameter.

[0033]

Τmax = Mz · r / Iz = 2Mz / πr3 =
16Mz / πD3 Mz is Mz2>Mz3>Mz4>Mz5> Mz as described above.
1 (subscript is the journal number). Therefore, when τmax is fixed, the relationship between the diameters D1 to D5 of the first to fifth journals is D2>D3>D4>D5> D1. Based on this relationship, in the present invention, the diameter of the second journal is set to the maximum and the diameter of the first journal is set to the minimum (D2> D3 ≧ D4 ≧ D5> D1). Therefore, the journal diameter can be set to an appropriate small value according to the torsional torque of each journal while maintaining the required strength.

By substituting the allowable stress for τmax in the above equation,
By substituting the maximum value of the torsional moment (see FIG. 3) into Mz, the minimum value (lower limit) of the journal diameter can be obtained. It is preferred to set all journal diameters to their respective minimum values, thereby maximizing the advantages of the present invention. However, even if the journal diameter is not set to the minimum value, the advantages of the present invention can be sufficiently obtained.

As described above, according to the present invention,
In consideration of the shear stress, the diameter of the journal is set differently based on the torsional torque. Thus, the journal diameter can be reduced while maintaining the strength of the crankshaft.

By reducing the diameter of the journal, the friction loss generated in the journal can be reduced. The friction shear force τ in lubrication of the journal portion is expressed by the following equation.

[0037]

Τ = μ · U / h = μ · (D · ω / 2) / h μ is the oil viscosity, h is the bearing clearance, U (= Dω / 2) is the relative speed of the journal bearing, and D is The journal diameter, ω, is the journal angular velocity. From this equation, it can be seen that reducing the journal diameter reduces the friction loss. In fact, reducing the diameter of the journal contributes significantly to reducing the friction loss of the entire engine.

Therefore, according to the present invention, since the friction loss is reduced, the fuel efficiency of the engine can be improved. Further, according to the present invention, the weight of the crankshaft and the entire engine can be reduced by reducing the diameter of the journal.

In this embodiment, a four-cylinder engine has been described, but the same applies to a case where the number of cylinders is different. In the in-line n-cylinder internal combustion engine, the torsional torque is maximum at the second journal and minimum at the first journal. Therefore, the diameter of the second journal D2 is set to the maximum, the diameter of the first journal D1 is set to the minimum, and the middle is set between the remaining journals J3 to J (n + 1). Each journal diameter is appropriately set based on the shear stress obtained from the torsional torque.

Next, a crank lubrication structure which is another characteristic of the present embodiment will be described.

Referring to FIG. 2, a journal oil supply hole 15 is provided through the cap 3b of the cylinder block 3. The journal oil holes 15 are provided in all five caps 3b corresponding to the five journals. Oil is supplied to the gap between the journal and the journal bearing through the oil supply hole 15.

The oil supply hole 15 can be provided in the block body on the 3a side instead of 3b.

Oil is supplied to the gap between the crankpin and the connecting rod bearing as follows. Four pin oil supply holes 17 to 23 are provided through the crankshaft. The pin lubrication hole 17 reaches from the first journal to the first pin, the pin lubrication hole 19 reaches from the third journal to the second pin, the pin lubrication hole 21 reaches from the fourth journal to the third pin, and the pin lubrication hole 17 is It reaches from the 5th journal to the 4th pin.

A part of the oil supplied to the journal is
The oil is supplied to the crank pin through these pin oil supply holes. Further, the piston, the piston ring, the cylinder and the piston pin are lubricated by a part of the oil supplied to the crank pin.

Here, attention is paid to the oil supply hole 19 to the second pin. In a conventional general crankshaft, as shown in FIG. 1, lubrication to a No. 2 pin is performed from a No. 2 journal. However, in this embodiment, refueling is performed from the third journal to the second pin. As described above, in the present invention, the third journal diameter is set small in consideration of the torsional torque. Since lubrication is performed from this small-diameter journal, the lubrication state of the second pin can be improved.

The reason why the refueling condition is improved is considered as follows.

A centrifugal force acts on the journal due to the rotation of the crankshaft, and a centrifugal force also acts on the oil supplied to the journal. To enter the oil hole to the crankpin, the oil must move in a direction opposite to the centrifugal force.

In the case of this embodiment, refueling is performed from the third journal having a small diameter. Therefore, since the centrifugal force acting on the oil is small, more oil can enter the oil supply hole and reach the crankpin.

In the journal, oil leaks from the bearing end and returns to the oil pan. Since the third journal has a small diameter, the amount of oil leakage is small. Also in this respect, the amount of lubrication to the second pin can be increased.

As described above, according to the present invention, the amount of lubrication to the crankpin can be increased, so that the lubrication state of the connecting rod bearing can be improved.

Particularly, in a high rotation state, the lubrication state of the crankpin becomes severe, and the load on the connecting rod bearing increases. On the other hand, the reduction of the centrifugal force and the reduction of the amount of oil leakage by reducing the diameter of the journal are remarkable at high rotation. Therefore, according to the present invention, it is possible to effectively improve a refueling state at a high rotation speed under severe conditions.

According to the present invention, the load on the connecting rod bearing can be reduced by improving the lubrication condition. Further, it is possible to increase the rotation speed of the internal combustion engine and reduce the size of the oil supply pump.

Here, the advantages of the present invention have been described by taking up the lubrication from the third journal to the second pin. However, lubrication to other crankpins is also performed from the journal whose diameter is reduced by applying the present invention, that is, the first, fourth, and fifth journals, and therefore, the lubrication condition is improved similarly to the second pin.

Although a four-cylinder engine has been described here, the same applies to engines with other numbers of cylinders. That is, the first pin is refueled from the first journal. For the remaining pins, lubricate pin n by n + 1
From the number journal. Thereby, a similar effect can be obtained. In a V-type engine or an engine having a larger number of crankpins than the main bearing such as a 3rd journal in a 4-cylinder engine, lubrication is performed from each journal, but the diameter of the 2nd journal is the maximum and the diameter of the 1st journal is the minimum.

[Brief description of the drawings]

FIG. 1 is a diagram showing a crankshaft of a conventional general internal combustion engine.

FIG. 2 is a diagram showing an internal combustion engine according to an embodiment of the present invention.

FIG. 3 is a diagram showing a torsional torque acting on a journal of a crankshaft.

[Explanation of symbols]

1 crankshaft, 1J 1st journal, 2J
2nd journal, 3J3rd journal, 4J 4th journal, 5J 5th journal, 1P 1st pin, 2P
2nd pin, 3P 3rd pin, 4P 4th pin, 3 cylinder block, 3a block body, 3b cap, 5 connecting rod, 9 timing belt pulley mounting part, 13 flange part, 15 journal oil hole, 1
7,19,21,23 Pin oil hole.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shigeo Suzuki 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. (72) Inventor Takanori Abekura Nagakute-machi, Aichi-gun, Aichi No. 41, No. 41, Changchun-ji, F-term in Toyota Central R & D Laboratories Co., Ltd. (reference) 3J033 AA02 BA06 BA13 BB10

Claims (3)

[Claims] 1. An internal combustion engine including a crankshaft having a plurality of journals, wherein journal diameters of the plurality of journals are set differently according to a difference in torsional torque acting on the journals. Internal combustion engine. 2. The internal combustion engine according to claim 1, wherein the internal combustion engine is an in-line n-cylinder type, the journal on the side opposite to the output shaft is the first journal, and the journal number increases as approaching the output shaft. The internal combustion engine wherein the second journal has a maximum journal diameter and the first journal has a minimum journal diameter. 3. The internal combustion engine according to claim 2, wherein the journal diameter of the third journal is set smaller than that of the second journal, and an oil supply hole for the second crank pin between the second journal and the third journal is provided. An internal combustion engine provided in a third journal.