JP2000352412A - Mounting structure of bearing cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a bolt for mounting such as a front cover and a flywheel housing from interfering with a side bolt, and to combine sealing property with rigidity of cranckshaft support. SOLUTION: In this mounting structure, a bearing cap is fastened by a main bolt 17 to the lower side of a journal wall 6 of a cylinder block 1, and the bearing cap is fastened to a skirt part 8 of the cylinder block 1 by a side bolt 20. In this case, the height of a side bolt 20F positioned at a front and a height of a side bolt 20R positioned at a back in a longitudinal direction of the cylinder block 1 are set higher than that of each of side bolts 20M which are positioned between the side bolts 20F and 20R. Accordingly, the side bolt is shifted to an upper side of a mounting bolt thereby preventing the side bolt from interfering with the mounting bolt. Further, since the side bolt is heightened by a node of a vibration of a cranckshaft, reduction of support rigidity can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing cap mounting structure applied to a crankshaft bearing of an engine.

[0002]

2. Description of the Related Art As a structure of a bearing for rotatably supporting a crankshaft of an engine, a half-split bearing cap is attached to a lower portion of a journal wall of a cylinder block, and the bearing surfaces of the journal wall and the bearing cap are joined together. In some cases, the journal portion of the crankshaft is sandwiched and supported from above and below.

[0003] As a mounting structure of the bearing cap, a bolt is generally fastened to the journal wall from below. In addition to this, there is also a structure in which the support stiffness is increased by fastening the side wall to the skirt portion with side bolts (particularly). Kaikai 61-12791
No. 5, etc.). This makes it possible to withstand high torsional and bending forces acting on the crankshaft, and to cope with higher engine output. Further, there is no such thing as the opening and closing vibration of the skirt portion, and the vibration noise is reduced.

In this case, a bolt for fastening the bearing cap to the journal wall is used for main fastening, and is called a main bolt. On the other hand, the side bolts are for auxiliary fastening.

[0005]

When the crankshaft is rotated due to the combustion pressure, a rotational force is applied to the bearing cap so as to rotate around the center of the crankshaft. The fastening from the side with the side bolts is to counter this rotational force. Therefore, the height position of the side bolt is preferably set as far as possible from the center of the crankshaft, that is, as low as possible.

On the other hand, a front cover is connected to the front end of the cylinder block, and a flywheel housing is connected to the rear end. A power transmission mechanism is housed in the front cover to transmit the rotational force of the crankshaft to the camshaft and pump pulley, etc. If this is a gear type or chain type that requires oil lubrication, Oil is circulated and scattered in the cover.
Also, oil is circulated and scattered in the flywheel housing by oil return and the like. Therefore, a sufficient sealing performance is required so that oil leakage does not occur at the joint of each member.

FIG. 5 shows an example of connection between the front end of the cylinder block a and the front cover b. As shown, an oil pan c is also connected to these lower portions. The connection of the front cover b to the cylinder block a
Using a bolt (not shown) from the front (left side in the figure). The connection of the oil pan c to the cylinder block a and the front cover b is also performed from below using bolts (not shown).

[0008] In this case, the seal tends to be sweet at the portion A where the three parts intersect. Therefore, in order to secure the seal, the position of the mounting bolt of the front cover b must be A
It is desirable to set near the part, that is, as low as possible.

However, a journal wall and a bearing cap also exist at the front end of the cylinder block, and side bolts also exist. As described above, it is preferable that the side bolts be as low as possible. At this time, there is a problem of interference between the side bolts and the mounting bolts.

[0010] A similar problem also occurs at the joint between the rear cylinder block and the flywheel housing.

[0011]

SUMMARY OF THE INVENTION The present invention provides a bearing cap mounting structure in which a bearing cap is fastened to a lower portion of a journal wall of a cylinder block by a main bolt, and the bearing cap is fastened to a skirt portion of the cylinder block by a side bolt. In this case, the height position of the front bolt located at the foremost or rearmost position in the front-back direction of the cylinder block is set higher than the height position of the side bolt located therebetween.

In this case, the side bolts escape above the front cover mounting bolts or the flywheel housing mounting bolts, so that mutual interference is prevented.

Generally, the bending and torsional forces acting on the crankshaft are maximized in the middle portion in the longitudinal direction of the crankshaft. In other words, if the crankshaft is a vibrating body, the middle part of the crankshaft is an antinode of vibration, and both ends are nodes of vibration. Therefore, the support rigidity at both ends can be slightly reduced as compared with the support rigidity at the intermediate portion. Therefore, even if the foremost or rearmost side bolt is higher than the middle side bolt as in the present invention, there is no problem in rigidity. This makes it possible to achieve both support rigidity and sealing performance.

[0014]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIGS. 1 to 4 show a cylinder block 1 of an engine to which the present invention is applied. For example, in FIG. 1, the left side is the front, and the right side is the back. Such a cylinder block 1 is for a V8 engine,
3, three cylinder bores 4 are formed in series. As shown in FIG. 2, at substantially the same position in the block front-back direction, one cylinder bore 4 is formed on each of the left and right sides, and a total of four cylinder bore sets 5 made up of two left and right parts are arranged in the block front-back direction. Are in series. A journal wall 6 is formed integrally with the cylinder block 1 so as to partition the cylinder bore set 5. The journal wall 6 is also provided in front of the frontmost cylinder bore set 5 and behind the rearmost cylinder bore set 5. That is, as shown in FIG. 3 and FIG. 4, the frontmost and rearmost journal walls 6F and 6R are a part of the front end wall 7F and the rear end wall 7R of the cylinder block 1. In this way, the journal walls 6 are provided adjacent to the four cylinder bore sets 5 before and after the cylinder bore set 5, so that there are a total of five journal walls 6. A skirt portion 8 is integrally formed on both sides of a lower portion of the cylinder block 1.

A bearing cap 9 is attached to a lower portion of each journal wall 6. As shown in detail in FIG. 2, the journal wall 6 and the bearing cap 9 are provided with semi-circular bearing surfaces 10 and 11 which are combined with each other to form a circle. ) Is rotatably supported by being sandwiched.

The upper surface 9a of the bearing cap 9 is joined to the lower surface 12 of the journal wall 6, and upper left and right side surfaces 13 are fitted to an upper fitting surface 14 formed inside the skirt portion 8. The lower boss portions 15 on the left and right sides are joined to a boss portion 16 formed to protrude inward near the lower end position of the skirt portion 8. On both left and right outer sides of the bearing surfaces 10 and 11, main bolts 17 for main fastening are vertically inserted into the bolt insertion holes 18 of the bearing cap 9 from below to above, and are screwed into the female screw holes 19 of the journal wall 6. After being fastened together, the main mounting of the bearing cap 9 is performed.

On the other hand, the side bolt 20 for auxiliary fastening is
It is inserted laterally from the left and right outer sides into the bolt insertion holes 21 of the skirt portion 8 and screwed and fastened to the female screw holes 19 of the bearing cap 9, whereby the bearing cap 9 is attached in an auxiliary manner. The bolt insertion hole 21 is provided at the center of the boss 16 and the female screw hole 19 is provided at the center of the lower boss 15.

As described above, since the bearing cap 9 receives a rotational force around the center of the crankshaft during rotation of the crankshaft, the height position of the side bolt 20 is set near the lower end of the bearing cap 9 to counter this. Is set.

By the way, as shown in FIG. 1, the height positions of the frontmost and rearmost side bolts 20F and 20R are set slightly higher than the height position of the side bolt 20M located therebetween. I have. That is, although the heights of the three intermediate bolts 20M are equal, the front and rear side bolts 20F and 20R are the same.
The height position of the height position than H _F thereof intermediate the side bolts 20M, only H _R high. Incidentally, the positions of the frontmost and rearmost boss portions 16, the lower boss portion 15, the bolt insertion holes 21 and the female screw holes 19 are also raised correspondingly. This has the following advantages.

FIG. 4 is a view of the cylinder block 1 as viewed from the rear. As can be seen, the rear end wall 7R of the cylinder block 1 has a rear connecting surface 21 for connecting a flywheel housing (not shown). Are formed. The rear connecting surface 21 is provided with a plurality of bolt holes 22. A female screw is provided on the inner periphery of the bolt hole 22.

As described above, since the bolt connection position of the flywheel housing is preferably as low as possible, a bolt hole 22D is provided at the lowest position of the rear connection surface 21. In this case, interference with the rear side bolt 20R is a problem. However, since the side bolt 20R is at a high position as described above, the side bolt 20R is inserted into the bolt hole 2R.
2D and thus can be released above the mounting bolt to be screwed thereto, so that interference can be avoided. That is, the bolt hole 22
The side bolt 20R passes vertically above D or the mounting bolt. Thus, the cylinder block 1,
Flywheel housing and oil pan (not shown)
At the intersection of the three, sealing performance is ensured and oil leakage can be reliably prevented.

The same can be said for the front front cover mounting portion. FIG. 3 is a view when the cylinder block 1 is viewed from the front. As can be seen, a front cover (not shown) is provided on the front end wall 7F of the cylinder block 1.
Is formed on the front surface 23 for coupling the two. The front connection surface 23 is also provided with a plurality of bolt holes 24 each having an internal thread on the inner periphery.

A bolt hole 24D is provided at the lowermost position of the front coupling surface 23. As described above, the side bolt 20F is provided.
Is located at a high position, the side bolt 20F can be released above the bolt hole 24D or the mounting bolt screwed into the bolt hole 24D, and interference between the side bolt 20F and the mounting bolt can be prevented. Also at the intersection of the cylinder block 1, the front cover, and the oil pan, the sealing performance is ensured, and oil leakage is reliably prevented.

On the other hand, even in this case, there is no problem in rigidity. That is, the bending force acting on the crankshaft,
The maximum torsional force is at the intermediate portion in the longitudinal direction of the crankshaft. Conversely, the forces are minimal at the ends, or at least smaller than at the middle. If the crankshaft is a vibrating body, the middle part of the crankshaft will be the antinode of vibration,
Both ends are nodes of vibration. Therefore, the support rigidity at both ends can be slightly reduced as compared with the support rigidity at the intermediate portion. Therefore, the most forward or rearmost side bolt 20
Even if F and 20R are higher than the intermediate side bolt 20M, there is no problem in rigidity. That is, since the side bolt is raised at the node of the vibration of the crankshaft, the supporting rigidity is not reduced to the extent that it is regarded as a problem. This makes it possible to achieve both support rigidity and sealability.

As described above, the embodiments of the present invention are not limited to those described above. For example, only one of the foremost or rearmost side bolts may be raised. In the above embodiment, the main bolts are inserted from below, and the main fastening is performed. However, a long main bolt may be vertically penetrated from above into the journal wall, and the main fastening may be performed using the main bolts. The auxiliary fastening method between the bearing cap and the skirt portion is not limited to the above-described method. If necessary, side bolts may be provided only on one of the left and right sides. In the above embodiment, the problem of bolt interference when the front cover and the flywheel housing are attached is a problem. However, these members are not limited to the front cover and the flywheel housing, and may be other members. The height positions of the intermediate side bolts are not necessarily equal,
The front bolt and the rearmost side bolt may be the same height or different heights. In short, it is sufficient that at least one of the foremost or rearmost side bolts is higher than any one of the intermediate side bolts.

[0027]

The present invention exhibits the following excellent effects.

(1) Interference between the mounting bolts of the front cover, the flywheel housing and the like and the side bolts can be prevented, and the sealing performance can be ensured.

(2) The support rigidity of the crankshaft can still be secured.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a left vertical sectional side view of FIG. 1 and is a cross-sectional view of an intermediate portion in a front-rear direction of a cylinder block.

FIG. 3 is a left side view of FIG.

FIG. 4 is a right side view of FIG.

FIG. 5 is a partial front view showing a connection state of a cylinder block, a front cover, and an oil pan.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 6 Journal wall 6F Foremost journal wall 6R Last journal wall 8 Skirt part 9 Bearing cap 17 Main bolt 20 Side bolt 20F Foremost side bolt 20R Last side bolt 20M Middle side bolt

Claims (1)

[Claims] In a bearing cap mounting structure in which a bearing cap is fastened to a lower portion of a journal wall of a cylinder block with a main bolt and the bearing cap is fastened to a skirt portion of the cylinder block with a side bolt, a bearing cap in a longitudinal direction of the cylinder block is provided. A mounting structure for a bearing cap, wherein the height position of a front bolt or a rearmost side bolt is set higher than the height position of a side bolt located therebetween.