JP2001082444A - Internal combustion engine with improved crank shaft supporting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent partial wearing in the journal at a crank end and reduce friction losses and the discharge of an oil pump. SOLUTION: In a crank shaft supporting structure, at least one of the journals at both ends of a crank shaft 3 is supported by roller bearings 15 and the other journals are supported by sliding bearings 17. Concretely, a first journal 1J is provided with the roller bearings 15 and the other journals 2J to 5J are provided with the sliding bearings 17. The fifth journal 5J may also be provided with another roller bearing 15 at the opposite end. The loading direction of a crank end is biased due to a timing belt load, an auxiliary belt load and a flywheel weight. Even under such conditions, partial wearing is prevented by the roller bearings 15. The roller bearings 15 reduce friction losses in a lower rotation area in normal use. In addition, since oil supply is unnecessary or let off a little amount, the discharge of the oil pump can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an internal combustion engine,
In particular, it relates to an improvement in a support structure of a crankshaft.

[0002]

2. Description of the Related Art As is well known, a crankshaft of an internal combustion engine has a plurality of journals, and the plurality of journals are supported on a cylinder block using main bearings. Usually, all the main bearings are constituted by sliding bearings, or all the main bearings are constituted by rolling bearings.

A plain bearing has the advantage of a simple structure. Further, since the oil film pressure is generated by the dynamic action of the lubricating oil film existing in the bearing gap and the load is supported by the oil film pressure, there is an advantage that a large load can be endured.

On the other hand, a rolling bearing has a complicated structure. Further, since the load is supported by using the rolling of the rolling element, there is an advantage that the friction coefficient in a low rotation range is small.
However, since it is not suitable for supporting a large load, it is often applied to a shaft having a relatively small load.

[0005]

A conventional general internal combustion engine often has a sliding bearing as a main bearing. In this type of internal combustion engine, uneven wear tends to occur in bearings at both ends. First, looking at the ends on the side where the timing belt, the accessory belt, and the like are attached, the load on these bearings is heavy because the load of these belts mainly acts upward. Looking at the end on the transmission side, a heavy load is attached to the lower part of the bearing because a heavy flywheel is attached. The effect of these biased loads is large in the low rotation range, and the low rotation range is also the normal rotation range. Therefore, uneven wear tends to occur in the bearings at both ends of the crank.

In order to prevent such uneven wear, conventionally, measures such as setting a wider bearing width and changing a material of a bearing overlay have been taken. However, these measures have the disadvantage of increasing frictional losses and costs.

Further, the rolling bearing type internal combustion engine is different from the above-mentioned plain bearing type internal combustion engine, and is advantageous for friction in a low rotation range. However, the damping effect by the lubricating oil as seen in a plain bearing cannot be expected. Therefore, under the impact load at the time of explosion, which is a feature of the internal combustion engine, the problem of vibration noise is relatively large. Under such circumstances, the application range of the rolling bearing type internal combustion engine is extremely limited.

The present invention has been made in view of the above background, and an object of the present invention is to provide a crank support structure capable of suppressing uneven wear and reducing friction loss.

[0009]

In order to achieve the above object, the present invention relates to an internal combustion engine including a crankshaft having a plurality of journals, wherein at least one of the journals at both ends of the crankshaft is supported by a rolling bearing. In addition, the remaining journals are supported by slide bearings. Specifically, the journal at the end on the belt drive side is supported by a rolling bearing. Further, the journal at the end on the transmission coupling side is supported by a rolling bearing.

According to the present invention, the journal at the end of the crank is supported by the rolling bearing. The rolling bearing can appropriately support a biased load acting on the crank end in a low rotation range. Moreover, the large load acting on the remaining journals is properly supported using the slide bearings. Further, the rolling bearing has low frictional resistance in a practically low rotation speed range. Furthermore, unlike sliding bearings, lubrication is not required or significantly reduced for rolling bearings.

As described above, according to the present invention, by appropriately combining and arranging a plain bearing and a rolling bearing, it is possible to prevent bearing uneven wear while maintaining bearing performance against an explosive load of an internal combustion engine, and to reduce bearing friction loss. In addition, the oil pump discharge amount can be reduced and the pump can be downsized. As a result, it is possible to contribute to extending the life of the engine, improving fuel efficiency, and reducing the size of the engine.

[0012]

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. 1 is a diagram showing a four-cylinder internal combustion engine of the present embodiment, and mainly shows only parts related to the configuration of the present invention. The configuration of a portion not shown may be basically the same as the configuration of a conventional general internal combustion engine.

In FIG. 1, a crankshaft 3 is rotatably supported by a cylinder block 1. One end of the crankshaft 3 is on the belt drive side, and the other end is on the transmission coupling side.

On the belt driving side, a timing belt driving pulley and an auxiliary belt driving pulley are mounted, and a toothed belt, a poly V belt and the like are hung on these pulleys. An oil pump rotor is also attached to the belt drive side. On the other hand, the transmission connection side is the output section of the internal combustion engine and also the input section of the transmission. Here, a flywheel or the like is attached. These configurations are generally conventional and are omitted from the drawings.

The internal combustion engine shown in FIG. 1 is, for example, a vertical four-cylinder gasoline engine. In this case, the belt drive side is disposed in front of the vehicle. Therefore, the belt drive side is referred to as “front”, and the transmission side is referred to as “rear”.

Next, the configuration around the crankshaft will be described. The crankshaft 3 has pins 1 to 4 (1P to 4P) at positions corresponding to the centers of the cylinders # 1 to # 4.
Having. A connecting rod 5 is attached to each of the pins 1P to 4P. A sliding bearing is mounted on the connecting rod side. A piston (not shown) is attached to the tip of the connecting rod.

The crankshaft 3 has five journals, ie, No. 1 to No. 5 so as to be alternately arranged with the pins.
No. journals (1J to 5J) are provided. Each journal and each pin are connected by a web with a counterweight. In front of the first journal 1J,
A mounting shaft 7 such as a belt drive pulley follows. Further, a transmission connecting shaft 9 continues to the rear of the fifth journal 5J.

Each of the journals 1J to 5J is supported by the cylinder block 1. More specifically, the cylinder block 1 includes a block body 11 and a bearing cap 13.
The main bearing is inserted into a housing formed by these components, and each journal is supported by the main bearing.

As a feature of the present invention, the first journal 1J, which is the end on the belt drive side, is supported by a rolling bearing 15 (ball bearing or roller bearing), and the remaining second to fifth journals 2J to 5J are sliding bearings. 17 supported. Lubricating oil is supplied to the second to fifth journals 2J to 5J through oil supply holes in the bearing cap.

Hereinafter, the features of the present invention will be described.

As described above, the timing belt and the accessory belt are hung on the belt driving side. Normally, from the viewpoint of the structure of the entire engine, and from the viewpoint of maintainability when mounted on a vehicle, the valve train and the auxiliary equipment are almost arranged at the top of the engine. The bending force by the belt acts upward as a whole, and an upward initial load acts near the forefront of the crankshaft. Under the operating conditions in which the engine speed is not high due to the influence of the initial load, the ratio of the time when the first journal 1J is located on the upper side in the bearing is large.

FIG. 2 shows the first journal 1J in this regard.
3 shows the transition of the load acting on the first journal 1
The axis locus in the gap circle of J is shown, and these are data for the low turning point area. The load always acts upward, and the axis center locus is located exclusively above the bearing division surface. As described above, the load on the upper half is large in the low rotation speed range, and this low rotation speed range is the practical rotation speed range of the internal combustion engine (for example, 3000 rpm).
rpm or less).

Conventionally, a sliding bearing is used for the first journal 1J as well as other journals. Therefore, there is a tendency that uneven wear of the upper half due to the uneven load occurs. This uneven wear may lead to a shortened bearing life. In addition, an increase in the bearing width and a change in the overlay material for the purpose of preventing uneven wear are disadvantageous in that friction loss and cost increase.

In view of such circumstances, in the present invention, the first journal 1J is supported by the rolling bearing 15, and the remaining journals 2J to 5J are supported by the sliding bearing 17. In the rolling bearing 15, the load is dispersed by the rotation and revolution of the rolling elements (balls, rollers, etc.). Therefore, even when the direction of the load by the journal is deviated, the occurrence of uneven wear is suppressed and prevented.

Further, since the sliding journals 17 are used for the remaining journals 2J to 5J, the explosion load in a high rotation range can be appropriately supported by the damping effect of the oil film.

Further, in the present invention, the friction loss is reduced and the fuel efficiency is improved. Practical rotation range of the engine (for example, 3000 rpm
m), the friction coefficient of the rolling bearing is originally smaller than the friction coefficient of the sliding bearing. The difference in the coefficient of friction in this region is, for example, 10 times or more, and when estimated based on this difference, the reduction rate of the friction loss is considered to be about 10 to 15%.

Further, in this embodiment, the discharge amount of the oil pump can be reduced as described below. Rolling bearings
Works well with grease and mist air lubrication and does not inherently require large amounts of lubricating oil. As is well known, the inside of the crankcase is filled with oil mist.
Therefore, as shown in FIG. 1, the bearing cap of the first journal 1J has no oil supply passage.

Since the bearing lubrication amount can be reduced in this way,
The amount of lubricating oil in the entire engine can also be reduced. And the discharge amount of the oil pump can also be reduced. Approximately, the reduction rate of the discharge amount of the oil pump is about 10%. Since the discharge amount may be small, the oil pump can be downsized,
The size of the internal combustion engine can be reduced. Further, the reduction in energy consumption of the oil pump also contributes to an improvement in fuel efficiency.

If the amount of oil in the rolling bearing is insufficient, it is preferable to adopt a structure as shown in FIG. Here, the bearing cap 21 of the first journal 1J has a branch oil hole 23 inside.
The branch oil hole 23 is provided in the main hole 2 for lubricating the sliding bearing.
It branches from 4. The branch oil hole 23 is significantly thinner than the oil supply hole 25 of another journal. The bearing outer ring 27 of the rolling bearing 15 has a shallow oil supply groove 28 on the outer peripheral surface.
The lubrication groove 28 is provided at the center in the bearing width direction, and extends around the bearing. Further, the bearing outer ring 27 is provided with a small-diameter oil supply hole 29.
Having. A plurality of oil supply holes 29 are provided at equal intervals in the circumferential direction. The oil is supplied from the main hole 24 to the oil supply groove 28 through the branch oil hole 23, reaches the inside of the bearing through the oil supply hole 29, and is further discharged from the side surface of the bearing.

By providing such an oil supply structure, necessary oil supply to the rolling bearing 15 is performed. Further, the amount of oil required for the rolling bearing 15 is originally small, and the branch oil hole 23 and the oil supply hole 29 are thin. Therefore, even with this structure, the discharge amount reduction effect of the present invention can be sufficiently obtained.

As described above, generally, a rolling bearing cannot be expected to have an effect of damping an oil film. Therefore, the rolling bearing is originally disadvantageous in terms of vibration and noise under special use conditions of the internal combustion engine in which an explosion and an impact load are repeatedly applied.

However, in the present invention, the rolling bearing is used for the first journal at the crank end. 1
As described above, in No. Journal, the load direction is biased due to the belt tension, and the load fluctuation due to the explosion is small.
Quasi-static load> is acting. Therefore, the problem of vibration and noise is small even if a rolling bearing is used. Although other journals have large load fluctuations, those journals are appropriately supported by the oil film damping effect of the slide bearing. Further, the load fluctuation of the first journal may be large in the high rotation region, but in this region, the vibration due to other conditions is intense. As described above, according to the arrangement of the rolling bearing in an appropriate position according to the present invention, the advantageous effects such as the prevention of uneven wear described above can be obtained without increasing the problem of vibration and noise.

In addition, in the embodiment of FIG. 1, lubrication from the first journal 1J to the first pin 1P cannot be performed. Therefore, it is preferable to refuel each pin from the journal on the rear side.

Next, another preferred embodiment of the present invention will be described with reference to FIG. In this embodiment, the fifth journal 5J, that is, the journal at the end on the transmission coupling side is supported by the rolling bearing 31 (ball bearing or roller bearing). The first journal 1J is also supported by the rolling bearing 15 as in the previous embodiment. The remaining journals 2J to 4J are supported by slide bearings 17. The lubrication hole for the 5th journal 5J has been abolished.

A feature of this embodiment is that the rolling bearing 31 is provided on the fifth journal in addition to the first journal as described above. This feature will be described below.

Since a heavy flywheel is attached to the fifth journal, a large load acts downward. Therefore, a downward initial load acts on the opposite of the first journal. In the low rotation speed range, which is the normal rotation range, the load direction is biased, and the time for which the journal is positioned downward is long. Therefore, when the sliding bearing is used for the fifth journal, uneven wear tends to occur as in the case of the first journal.

On the other hand, according to the present invention, since the rolling bearing is provided on the fifth journal, the load is dispersed by the rotation and revolution of the rolling element. Therefore, even under the condition that the load acts unevenly, the occurrence of uneven wear is suppressed and prevented.

Further, by providing a rolling bearing on the fifth journal, the same advantages as those described above for the first journal can be obtained. That is, due to the friction reducing effect of the rolling bearing, the friction loss is reduced, and the fuel efficiency is improved. Further, the discharge amount of the oil pump can be reduced, and advantages such as downsizing of the pump can be obtained. If necessary, a structure for supplying a small amount of oil may be provided similarly to the structure shown in FIG. Furthermore, since a quasi-static load acts on the journal at the crank end in the low rotation range, there is little problem of vibration and noise associated with the rolling bearing. The friction loss and the reduction rate of the pump discharge amount of this configuration are roughly estimated to be 1.5 times or more as compared with the configuration of FIG.
It is considered to be twice.

In addition, in this embodiment, lubrication from the fifth journal 5J to the fourth pin 4P cannot be performed. So 4
It is preferable to refuel the number pin 4P from the number 4 journal 4J. Refueling of the remaining pins 1P to 3P is performed from journals 2J to 4J. However, in one of these, it is necessary to simultaneously refuel one pin from two journals on both sides. Therefore, it is preferable to make the diameter of the oil hole of the corresponding journal portion and the diameter of the oil hole 25 of the bearing cap portion larger than usual so that the oil supply amount to the pin does not decrease. As a specific configuration example, the pins 1P and 2P
Refuel from journals 2J and 3J, respectively. The pins 3P and 4P are refueled from the journal 4J. At this time, for the journal 4J, the oil hole diameters of the journal portion and the bearing cap portion are changed to the other journals 2J, 3J.
Set larger than J.

Next, a modified example of this embodiment will be described. This embodiment does not limit the present invention, and it is needless to say that the present invention can be freely modified within the scope of the present invention.
For example, the type of the internal combustion engine is arbitrary, and even if the engine is not a four-cylinder engine, the engine is not an in-line engine (V type, horizontally opposed, etc.)
However, an engine other than a vertical one or an engine other than gasoline (such as diesel) may be used. Further, the internal combustion engine may be used for a vehicle or may be used for other purposes. The rolling bearing may be provided only on the transmission connection side, not on the belt drive side.

[0042]

As described above, according to the present invention, since the journal at the crank end is supported by the rolling bearing, bearing uneven wear can be prevented, and a large load can be appropriately applied by the sliding bearings of the remaining journals. Can be supported. Further, the friction loss can be reduced, and the required oil supply amount of the oil pump can be reduced.

Therefore, by appropriately combining and arranging the sliding bearing and the rolling bearing, while maintaining the bearing performance against the explosive load of the internal combustion engine, uneven wear is prevented, the friction loss is reduced, and the oil pump discharge is reduced. It is also possible to reduce the volume and the size of the pump accordingly. As a result, it is possible to contribute to extending the life of the engine, improving fuel efficiency, and reducing the size of the engine.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a view showing a load acting on a first journal.

FIG. 3 is a view showing an axis locus of a first journal.

FIG. 4 is a view showing a modification of the oil supply structure of FIG.

FIG. 5 is a diagram showing a main part of an internal combustion engine according to another embodiment of the present invention.

[Explanation of symbols]

1 cylinder block, 3 crankshafts, 15
Rolling bearings, 17 plain bearings.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takanori Abekura 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside of Toyota Central R & D Laboratories Co., Ltd. (1) Inside Toyota Toyota Central Research Institute, Inc. (72) Inventor Toshihiro Ozasa Toshihiro Ozasa 41, Nagakute-machi, Nagakute-cho, Aichi Prefecture, Japan Inside Toyota Central Research Institute Inc. (72) Inventor Yoshihiko Masuda Aichi 1 Toyota Town, Toyota Prefecture F-term in Toyota Motor Corporation (reference) 3J033 AA02 AA05 GA05 GA08 GA20

Claims (3)

[Claims] 1. An internal combustion engine including a crankshaft having a plurality of journals, wherein at least one of journals at both ends of the crankshaft is supported by a rolling bearing, and the remaining journals are supported by a sliding bearing. Internal combustion engine. 2. The internal combustion engine according to claim 1, wherein the journal at the end on the belt drive side is supported by a rolling bearing. 3. The internal combustion engine according to claim 1, wherein a journal at an end on a transmission coupling side is supported by a rolling bearing.