JP2015064009A - Bearing structure of crank shaft of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing structure of a crank shaft of an internal combustion engine in which deterioration in lubricity between a crank journal and a journal bearing part can be prevented by preventing an increase in an amount of a lubricant leaking from a clearance between the crank journal and the journal bearing part due to a thermal expansion difference between the crank shaft and a cylinder block.SOLUTION: Outer circumferential surfaces of crank journals 11 provided at an axial one side and the other side with respect to a center part 26 of a cylinder block in an axial line direction of a crank shaft 3 have tapered surfaces 11A, 11B which gradually diametrically enlarged toward the outside of the axial one side and the other side from the center part 26 side of the cylinder block 2. Inner circumferential surfaces of an upper journal bearing part 22 and a lower journal bearing part 23 which oppose the crank journals 11 provided at the axial one side and the other side with respect to the center part 26 of the cylinder block 2 have tapered surfaces 22B, 23B which gradually diametrically enlarged toward the outside of the other side of the axial line direction from the center part 26 side of the cylinder block 2.

Description

  The present invention relates to a bearing structure for a crankshaft of an internal combustion engine mounted on a vehicle.

  In an internal combustion engine mounted on a vehicle, the reciprocating motion of a piston is converted into the rotational motion of a crankshaft via a connecting rod, and the crank journal is connected to the journal via a journal bearing. The cylinder block is rotatably supported.

  Conventionally, as a bearing structure of this type of crankshaft, for example, those described in Patent Documents 1 and 2 are known. In this crankshaft bearing structure, the journal bearing portion is constituted by a semi-cylindrical upper bearing member and a lower bearing member, and the outer peripheral surface of the crank journal of the crankshaft and the inner side of the upper bearing member and the lower bearing member. The peripheral surface is formed on a surface parallel to the axial direction of the crankshaft.

  Further, as shown in Patent Document 2, an oil passage perpendicular to the axial direction of the crankshaft is formed in the upper bearing member, and the sliding portion between the crank journal and the journal bearing portion is lubricated through this oil passage. By supplying the oil, the crank journal and the journal bearing portion are lubricated.

JP 09-242745 A JP 2006-125565 A

  However, in such a conventional crankshaft bearing structure of an internal combustion engine, the outer peripheral surface of the crank journal and the inner peripheral surfaces of the upper bearing member and the lower bearing member are parallel to the axial direction of the crankshaft. Therefore, when the internal combustion engine is at a high temperature, the cylinder block is thermally deformed in the axial direction and the radial direction of the crankshaft starting from the central portion of the cylinder block in the axial direction of the crankshaft.

  Specifically, when the cylinder block is made of an aluminum-based material such as an aluminum alloy and the crankshaft is made of an iron-based material such as cast iron, the thermal expansion coefficient of the cylinder block is higher than that of the crankshaft. Therefore, the cylinder block is thermally deformed in the axial direction and the radial direction of the crankshaft when the internal combustion engine is actually operated at a high temperature.

  For this reason, a gap between the outer peripheral surface of the crank journal and the inner peripheral surfaces of the upper bearing member and the lower bearing member becomes large, and the outer peripheral surface of the crank journal and the inner peripheral surfaces of the upper bearing member and the lower bearing member become larger. The lubricating oil supplied therebetween leaks from between the outer peripheral surface of the crank journal and the inner peripheral surfaces of the upper bearing member and the lower bearing member. Therefore, it is difficult to form a lubricating oil film on the outer peripheral surface of the crank journal and the inner peripheral surfaces of the upper bearing member and the lower bearing member, and the outer peripheral surface of the crank journal and the inner peripheral surfaces of the upper bearing member and the lower bearing member There is a risk that the lubricity of the rubber will deteriorate.

  The present invention has been made paying attention to the above-described problems, and the amount of lubricating oil leaking from between the crank journal and the journal bearing portion increases due to the difference in thermal expansion between the crankshaft and the cylinder block. It is an object of the present invention to provide a crankshaft bearing structure for an internal combustion engine that can prevent the deterioration of lubricity between the crank journal and the journal bearing portion.

  In the first aspect of the present invention, a plurality of journal bearing portions are provided in the lower part of a cylinder block having a plurality of cylinder bores along the arrangement direction of the cylinder bores, and the crank journal of the crankshaft is rotatably supported by the journal bearing portions. A crankshaft bearing structure of an internal combustion engine, wherein an outer peripheral surface of a crank journal provided on one side in the axial direction with respect to the central portion of the cylinder block in the axial direction of the crankshaft is from the central portion side of the cylinder block The outer peripheral surface of the crank journal provided on the other side in the axial direction with respect to the center portion of the cylinder block has a tapered surface that gradually increases in diameter toward the outer side on the one side in the axial direction. Has a tapered surface that gradually increases in diameter toward the outside on the other side in the axial direction. The inner peripheral surface of the journal bearing portion facing the crank journal provided on one side in the axial direction with respect to the portion has a tapered surface that gradually increases in diameter from the central portion side toward the outer side on the one side in the axial direction. And the inner peripheral surface of the journal bearing portion facing the crank journal provided on the other side in the axial direction with respect to the center portion of the cylinder block is directed outward from the center portion side of the cylinder block to the other side in the axial direction. It is comprised from what has the taper surface which expands gradually.

  As a second aspect of the present invention, the journal bearing portion protrudes downward from the partition portion of the cylinder block that partitions the cylinder bores along the arrangement direction, and supports a semicircular inner periphery that supports the outer peripheral surface of the upper half of the crank journal. An upper journal bearing portion having a surface, a semicircular inner peripheral surface supporting the outer peripheral surface of the lower half of the crank journal, and a lower journal bearing portion attached to the upper journal bearing portion, and an inner portion of the upper journal bearing portion A bearing body interposed between the peripheral surface and the inner peripheral surface of the lower journal bearing portion and the outer peripheral surface of the crankshaft, the inner peripheral surface of the upper journal bearing portion and the inner periphery of the lower journal bearing portion A tapered surface is formed on the surface, and the bearing body extends along the inner peripheral surface of the upper journal bearing portion and the inner peripheral surface of the lower journal bearing portion and the outer peripheral surface of the crank journal. Good.

  As described above, according to the first aspect, the outer peripheral surface of the crank journal provided on one side and the other side in the axial direction with respect to the central portion of the cylinder block in the axial direction of the crankshaft is the central portion of the cylinder block. Journal having a tapered surface that gradually increases in diameter from the side toward the outside in one axial direction and the other in the axial direction, and opposed to the crank journal provided on one side and the other side in the axial direction with respect to the central portion of the cylinder block The inner peripheral surface of the bearing portion has a tapered surface that gradually increases in diameter from the center portion side of the cylinder block toward the outer side on one side and the other side in the axial direction.

  For this reason, the cylinder block expands in the radial direction of the crankshaft in addition to the one side and the other side in the axial direction with respect to the center portion of the cylinder block due to a difference in thermal expansion between the cylinder block and the crankshaft during actual operation when the internal combustion engine becomes hot. In this case, the taper surface of the journal bearing portion is displaced along the taper surface of the crank journal in one axial direction of the crankshaft and the radial direction of the crankshaft, or in the other axial direction of the crankshaft and the radial direction of the crankshaft. .

  At this time, since the gap between the taper surface of the journal bearing portion and the taper surface of the crank journal does not increase, it is possible to prevent an increase in the amount of lubricating oil leaking from between the journal bearing portion and the crank journal. it can. For this reason, an oil film for lubricating the journal bearing portion and the crank journal can be formed between the journal bearing portion and the crank journal, thereby preventing the lubricity between the crank journal and the journal bearing portion from deteriorating. be able to. As a result, it is possible to prevent an increase in the sliding resistance of the crankshaft with respect to the journal bearing portion, thereby preventing deterioration in fuel consumption of the internal combustion engine.

  According to said 2nd aspect, a taper surface is formed in the internal peripheral surface of an upper journal bearing part, and the internal peripheral surface of a lower journal bearing part, and a bearing body is the internal peripheral surface of an upper journal bearing part, and a lower journal bearing part. It extends along the inner peripheral surface of.

  For this reason, the cylinder block has a diameter of the crankshaft in addition to one side and the other side in the axial direction of the crankshaft with respect to the central portion of the cylinder block due to a difference in thermal expansion between the cylinder block and the crankshaft during actual operation when the internal combustion engine is at a high temperature. In the case of expansion in the direction, the taper surfaces of the upper journal bearing portion and the lower journal bearing portion are displaced in the radial direction of the crankshaft in addition to the one axial side and the other axial direction of the crankshaft along the tapered surface of the crank journal. .

At this time, the gap between the taper surface of the upper journal bearing portion and the taper surface of the lower journal bearing portion and the taper surface of the crank journal does not increase, so that there is no gap between the inner peripheral surface of the bearing body and the outer peripheral surface of the crank journal. It is possible to prevent an increase in the amount of lubricating oil leaking from the vehicle.
Therefore, an oil film for lubricating the bearing body and the crank journal can be formed between the bearing body and the crank journal, and deterioration of the lubricity between the crank journal and the journal bearing portion can be prevented. .

FIG. 1 is a view showing an embodiment of a bearing structure for a crankshaft of an internal combustion engine according to the present invention, and is a cross-sectional view of a cylinder block of the internal combustion engine. FIG. 2 is a view showing an embodiment of a bearing structure for a crankshaft of an internal combustion engine according to the present invention, and is an enlarged sectional view of a cylinder block around the crankshaft. FIG. 3 is a diagram showing an embodiment of a bearing structure for a crankshaft of an internal combustion engine according to the present invention, in which a journal block and a crank journal of a journal block when a cylinder block thermally expands in one axial direction with respect to the central portion. It is a figure which shows a state. FIG. 4 is a diagram showing an embodiment of a bearing structure for a crankshaft of an internal combustion engine according to the present invention, in which a journal block and a crank journal of a journal block when the cylinder block thermally expands to the other side in the axial direction with respect to the central part. It is a figure which shows a state.

Embodiments of a bearing structure for a crankshaft of an internal combustion engine according to the present invention will be described below with reference to the drawings.
1 to 4 are views showing a bearing structure of a crankshaft of an internal combustion engine according to an embodiment of the present invention.
First, the configuration will be described. In FIG. 1, an in-line three-cylinder engine 1 as an internal combustion engine provided in a vehicle includes a crankcase integrated cylinder block 2. A cylinder head (not shown) is attached to the upper part of the cylinder block 2, and an oil pan (not shown) is attached to the lower part of the cylinder block 2. The engine 1 is a crank that rotates through the combustion pressure caused by the explosion of the air-fuel mixture. A shaft 3 is provided. In addition, the engine 1 of FIG. 1 is the figure seen from the front side of the vehicle.

  A flywheel 4 is provided at one axial end of the crankshaft 3 (right end of the vehicle), and a timing belt (not shown) is provided at the other axial end of the crankshaft 3 (left end of the vehicle). A pulley 5 for driving an auxiliary machine (not shown) is provided. Hereinafter, the axial direction when simply expressed as the axial direction is the axial direction of the crankshaft 3.

  The cylinder block 2 is provided with three cylinder bores 6, and pistons 7 are accommodated in the respective cylinder bores 6 so as to be reciprocally movable. The piston 7 is connected to the crankshaft 3 via a connecting rod 8.

  1 and 2, the crankshaft 3 includes a crankpin 10 to which a connecting rod 8 is connected via a slide bearing 9, a crank journal 11 that is rotatably supported by a journal bearing portion 21, and a crankpin 10. A crankpin 10 that connects the crank journal 11 and a counterweight 12 for balancing the rotation of the crankshaft 3 are included.

  The journal bearing portion 21 includes an upper journal bearing portion 22. The upper journal bearing portion 22 projects downward from the partition portion 2A of the cylinder block 2 that partitions the cylinder bores 6 along the arrangement direction. Therefore, the upper journal bearing portion 22 is provided integrally with the cylinder block 2. A semicircular inner peripheral surface that supports the outer peripheral surface of the upper half of the crank journal 11 is formed on the inner peripheral surface of the upper journal bearing portion 22.

  The journal bearing portion 21 includes a lower journal bearing portion 23. The lower journal bearing portion 23 has a semicircular inner peripheral surface that supports the outer peripheral surface of the lower half of the crank journal 11, and a bolt. 24 is attached to the upper journal bearing portion 22.

The journal bearing portion 21 is provided with a sliding bearing 25 as a bearing body. The sliding bearing 25 includes an inner peripheral surface of the upper journal bearing portion 22, an inner peripheral surface of the lower journal bearing portion 23, and the crankshaft 3. It is interposed between the outer peripheral surfaces of. Specifically, the sliding bearing 25 includes a halved bearing portion 25 </ b> A interposed between the inner peripheral surface of the upper journal bearing portion 22 and the outer peripheral surface of the crank journal 11, and an inner portion of the lower journal bearing portion 23. It is composed of a half-shaped bearing portion 25 </ b> B interposed between the peripheral surface and the outer peripheral surface of the crank journal 11.
Here, in the engine 1 of the present embodiment, the crankshaft 3 is made of an iron-based material such as cast iron, and the cylinder block 2 including the journal bearing portion 21 is made of an aluminum-based material such as an aluminum alloy. . The sliding bearing 25 is made of an aluminum-based material such as an aluminum alloy that is the same material as the cylinder block 2.

On the other hand, as shown in FIG. 2, the outer peripheral surface of the crank journal 11 provided on one side in the axial direction with respect to the central portion 26 of the cylinder block in the axial direction of the crankshaft 3 is from the central portion 26 side of the cylinder block 2. It has a tapered surface 11A that gradually increases in diameter toward the outside on one side in the axial direction (right side of the vehicle).
The outer peripheral surface of the crank journal 11 provided on the other side in the axial direction (the left side of the vehicle) with respect to the central portion 26 of the cylinder block 2 is outward from the central portion 26 side of the cylinder block 2 to the other side in the axial direction. It has a tapered surface 11B that gradually increases in diameter.

  The inner peripheral surfaces of the upper journal bearing portion 22 and the lower journal bearing portion 23 facing the crank journal 11 provided on one side in the axial direction with respect to the central portion 26 of the cylinder block 2 are from the central portion 26 side of the cylinder block 2. Tapered surfaces 22A and 23A that gradually increase in diameter toward the outside on one side in the axial direction are provided.

  The inner peripheral surfaces of the upper journal bearing portion 22 and the lower journal bearing portion 23 facing the crank journal 11 provided on the other axial side with respect to the central portion 26 of the cylinder block 2 are from the central portion 26 side of the cylinder block 2. Tapered surfaces 22B and 23B that gradually increase in diameter toward the outside on the other side in the axial direction are provided.

  Further, each of the bearing portions 25A and 25B constituting the slide bearing 25 includes tapered surfaces 22A, 22B, 23A and 23B which are inner peripheral surfaces of the upper journal bearing portion 22 and the lower journal bearing portion 23, and an outer peripheral surface of the crank journal 11. It extends along the tapered surfaces 11A and 11B. That is, the sliding bearing 25 is formed in a hollow conical shape. The tapered surfaces 22A, 22B, 23A, and 23B of the present embodiment correspond to the tapered surfaces of the journal bearing portion 21.

  Each upper journal bearing portion 22 is provided with a lubricating oil supply passage 27, and the lubricating oil supply passage 27 passes through a lubricating oil main supply passage formed in the cylinder block 2 from an oil pump (not shown). Is to be supplied.

  The lubricating oil supply passage 27 supplies the lubricating oil supplied through the lubricating oil main supply passage between the sliding bearing 25 and the crank journal 11 through the oil hole 25a formed in the bearing portion 25A. The sliding bearing 25 and the crank journal 11 are lubricated with lubricating oil.

Next, the operation will be described.
When the engine 1 is at a high temperature, the cylinder block 2 is cranked in addition to the right and left sides of the vehicle with respect to the central portion 26 in the axial direction due to the difference in thermal expansion between the cylinder block 2 and the crankshaft 3. The shaft 3 expands in the radial direction.

  In the engine 1 of the present embodiment, the outer peripheral surface of the crank journal 11 provided on one side in the axial direction with respect to the central portion 26 of the cylinder block in the axial direction of the crankshaft 3 extends from the central portion 26 side of the cylinder block 2 to the axial line. 11A has a tapered surface 11A that gradually increases in diameter toward the outer side on the one side (right side of the vehicle) and faces the crank journal 11 provided on the other side in the axial direction with respect to the central portion 26 of the cylinder block 2 The inner peripheral surfaces of the upper journal bearing portion 22 and the lower journal bearing portion 23 are tapered surfaces 22A, 23A that gradually increase in diameter from the central portion 26 side of the cylinder block 2 toward the outside in the other axial direction.

  In addition, each of the bearing portions 25 </ b> A and 25 </ b> B extends along the tapered surfaces 22 </ b> A and 23 </ b> A of the upper journal bearing portion 22 and the lower journal bearing portion 23 and the tapered surface 11 </ b> A of the crank journal 11.

  For this reason, as shown in FIG. 3, when the engine 1 is at a high temperature, the tapered surface 22A of the upper journal bearing portion 22 and the tapered surface 23A of the lower journal bearing portion 23 are The journal 11 is displaced along the tapered surface 11A by displacement amounts L1 and L2 in the right side of the vehicle, which is one side in the axial direction of the crankshaft 3, and in the radial direction of the crankshaft 3. The sliding bearing 25 is also displaced in the right side of the vehicle, which is one side in the axial direction of the crankshaft 3, and in the radial direction of the crankshaft 3.

  At this time, the gap between the taper surface 22A of the upper journal bearing portion 22 and the taper surface 23A of the lower journal bearing portion 23 and the taper surface 11A of the crank journal 11 does not increase, so the gap between the slide bearing 25 and the crank journal 11 Will not grow. For this reason, when lubricating oil O is supplied between the sliding bearing 25 and the crank journal 11, it can prevent that the amount of lubricating oil leaking from between the sliding bearing 25 and the crank journal 11 increases. . Therefore, an oil film for lubricating the sliding bearing 25 and the crank journal 11 can be formed between the sliding bearing 25 and the crank journal 11, and the lubricity between the sliding bearing 25 and the crank journal 11 is deteriorated. Can be prevented.

  On the other hand, in the engine 1 of the present embodiment, the inner peripheral surfaces of the upper journal bearing portion 22 and the lower journal bearing portion 23 facing the crank journal 11 provided on the other side in the axial direction with respect to the central portion 26 of the cylinder block 2 are provided. The crank block 23A has a tapered surface 23A that gradually increases in diameter from the central portion 26 side of the cylinder block 2 toward the outer side of the one axial direction, and is provided on the other axial side with respect to the central portion 26 of the cylinder block 2 Inner peripheral surfaces of the upper journal bearing portion 22 and the lower journal bearing portion 23 facing the journal 11 have a tapered surface 23B that gradually increases in diameter from the central portion 26 side of the cylinder block 2 toward the outer side in the axial direction. .

  In addition to this, each of the bearing portions 25A and 25B extends along the tapered surfaces 22B and 23B of the upper journal bearing portion 22 and the lower journal bearing portion 23 and the tapered surfaces 11A and 11B of the crank journal 11. .

  For this reason, as shown in FIG. 4, when the engine 1 is at a high temperature, the tapered surface 22B of the upper journal bearing 22 and the tapered surface 23B of the lower journal bearing 23 are The journal 11 is displaced along the taper surface 11B by displacements L1 and L2 on the left side of the vehicle, which is one side in the axial direction of the crankshaft 3, and in the radial direction of the crankshaft 3. The sliding bearing 25 is also displaced in the left side of the vehicle, which is one side in the axial direction of the crankshaft 3, and in the radial direction of the crankshaft 3.

At this time, the gap between the taper surface 22B of the upper journal bearing portion 22 and the taper surface 23B of the lower journal bearing portion 23 and the taper surface 11B of the crank journal 11 does not increase, so the gap between the slide bearing 25 and the crank journal 11 Will not grow. For this reason, when lubricating oil O is supplied between the sliding bearing 25 and the crank journal 11, it can prevent that the amount of lubricating oil leaking from between the sliding bearing 25 and the crank journal 11 increases. . Therefore, an oil film for lubricating the sliding bearing 25 and the crank journal 11 can be formed between the sliding bearing 25 and the crank journal 11, and the lubricity between the sliding bearing 25 and the crank journal 11 is deteriorated. Can be prevented.
As a result, the sliding resistance of the crankshaft 3 with respect to the journal bearing portion 21 can be prevented from increasing, and the fuel consumption of the engine 1 can be prevented from deteriorating.
3 and 4, the relative displacement amount between the journal bearing portion 21 and the crank journal 11 is shown to be large for easy understanding of the relative displacement amounts L1 and L2 between the journal bearing portion 21 and the crank journal 11. However, the actual relative displacement amounts L1 and L2 are smaller than shown.

In the engine 1 of the present embodiment, the lubricant supply passage 27 is formed in the upper journal bearing portion 22. However, the present invention is not limited to this. For example, an axial oil passage that is formed in the axial direction of the crankshaft 3 and is supplied with lubricating oil from an oil pump, and extends in a radial direction from the axial oil passage, is connected to the journal bearing portion 21 and the crank journal 11. You may comprise a lubricating oil supply path from the radial direction oil path connected between.
While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 2 ... Cylinder block, 2A ... Partition part, 3 ... Crankshaft, 6 ... Cylinder bore, 11 ... Crank journal, 11A, 11B ... Tapered surface, 21 ... Journal bearing part, 22 ... Upper journal bearing , 22A, 22B, 23A, 23B ... tapered surface (tapered surface of journal bearing portion), 23 ... lower journal bearing portion, 25 ... slide bearing (bearing body), 26 ... center portion (center portion of cylinder block)

Claims (2)

A crankshaft of an internal combustion engine in which a plurality of journal bearing portions are provided at a lower portion of a cylinder block having a plurality of cylinder bores along an arrangement direction of the cylinder bores, and a crank journal of a crankshaft is rotatably supported by the journal bearing portions. The bearing structure of
The outer peripheral surface of the crank journal provided on one side in the axial direction with respect to the central portion of the cylinder block in the axial direction of the crankshaft is outward from the central portion side of the cylinder block to the one side in the axial direction. Having a tapered surface that gradually expands toward the
A taper in which an outer peripheral surface of the crank journal provided on the other side in the axial direction with respect to the center portion of the cylinder block gradually increases in diameter from the center portion side of the cylinder block toward the outside on the other side in the axial direction. Has a surface,
An inner peripheral surface of the journal bearing portion facing the crank journal provided on one side in the axial direction with respect to the central portion of the cylinder block is an outer side on the one side in the axial direction from the central portion side of the cylinder block. Having a tapered surface that gradually expands toward
The inner peripheral surface of the journal bearing portion facing the crank journal provided on the other axial side with respect to the central portion of the cylinder block is outward from the central portion side of the cylinder block to the other axial direction side. A bearing structure for a crankshaft of an internal combustion engine, characterized by having a tapered surface that gradually increases in diameter toward the center. The upper journal bearing having a semicircular inner peripheral surface that protrudes downward from a partition portion of the cylinder block that partitions the cylinder bores along the arrangement direction and supports the outer peripheral surface of the upper half of the crank journal. And a lower journal bearing portion attached to the upper journal bearing portion, an inner circumferential surface of the upper journal bearing portion, and a semicircular inner circumferential surface supporting a lower half outer circumferential surface of the crank journal A bearing body interposed between the inner peripheral surface of the lower journal bearing portion and the outer peripheral surface of the crankshaft,
The tapered surface is formed on the inner peripheral surface of the upper journal bearing portion and the inner peripheral surface of the lower journal bearing portion, and the bearing body is an inner peripheral surface of the upper journal bearing portion and an inner peripheral surface of the lower journal bearing portion. The crankshaft bearing structure for an internal combustion engine according to claim 1, wherein the bearing extends along the outer peripheral surface of the crank journal.

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