WO2021060260A1

WO2021060260A1 - Fastening structure

Info

Publication number: WO2021060260A1
Application number: PCT/JP2020/035761
Authority: WO
Inventors: 本間　伸一; 大雅日比
Original assignee: いすゞ自動車株式会社
Priority date: 2019-09-27
Filing date: 2020-09-23
Publication date: 2021-04-01
Also published as: JP2021055573A; CN114450474A

Abstract

A fastening structure 100 in which a cylinder head 2 is fastened to a cylinder block 1 using a bolt 3. The cylinder block 1 is provided with: a plurality of cylinder bores 10; a water jacket 20; a bore wall 30; a jacket wall 40; a boss section 50 that is formed on the jacket wall 40 at a location between the cylinder bores 10; and an internal thread hole 60 formed in the boss section 50. An inclined surface 22 is provided to a bottom surface 21 of the water jacket 20 within a predetermined angular range β where a reference position A1 is the location between the cylinder bores 10 and the center is set to a center location A2 that is offset by a predetermined angle α about a center X of the internal thread hole 60.

Description

Fastening structure

This disclosure relates to the fastening structure.

In an internal combustion engine, a fastening structure is known in which a cylinder head is fastened to a cylinder block with bolts.

Generally, in this fastening structure, the cylinder block is formed between a bore wall formed between a plurality of cylinder bores and a water jacket, a jacket wall formed on the outside of the water jacket facing the bore wall, and a cylinder bore. It is provided with a boss portion formed on the jacket wall at the position. A female screw hole into which a bolt is screwed is formed in the boss portion.

Japanese Patent Application Laid-Open No. 11-6462

By the way, in the above fastening structure, when the cylinder head is fastened to the cylinder block, the boss portion is pulled toward the cylinder head side centering on the female screw hole. As a result, for example, on the bottom surface of the water jacket, stress may be concentrated in a portion adjacent to the boss portion. Such stress concentration causes fatigue fracture and the like.

Therefore, the present disclosure was devised in view of such circumstances, and an object thereof is to suppress stress concentration in a fastening structure in which a cylinder head is fastened to a cylinder block with bolts.

According to one aspect of the present disclosure, the fastening structure is such that the cylinder head is fastened to the cylinder block with bolts, and the cylinder block includes a plurality of cylinder bores, a water jacket surrounding the plurality of cylinder bores, and the plurality of cylinder blocks. A bore wall formed between the cylinder bore and the water jacket, a jacket wall formed on the outside of the water jacket facing the bore wall, one cylinder bore of the plurality of cylinder bores, and the plurality of cylinder bores. The jacket wall is provided with a boss portion formed on the jacket wall at a position between the cylinder bores, which is a position between the cylinder bores, and a female screw hole formed on the boss portion and into which the bolt is screwed. The bottom surface of the water jacket is provided with an inclined surface within a predetermined angle range centered on a center position deviated by a predetermined angle around the center of the female screw hole with the position between the cylinder bores as a reference position. A fastening structure is provided.

Preferably, the inclined surface is inclined toward the cylinder head side as the angle from the start position on the reference position side increases within the angle range.

Preferably, the passage width of the water jacket is formed to be the first width within the angle range when the angle from the start position is within a predetermined angle, and the angle from the start position is greater than the predetermined angle. At a position larger than the first width, a second width larger than the first width is formed.

According to the present disclosure, stress concentration can be suppressed in a fastening structure in which the cylinder head is fastened to the cylinder block with bolts.

FIG. 1 is a plan sectional view showing a schematic configuration of a cylinder block in a fastening structure. FIG. 2 is a cross-sectional view taken along the line II-II shown in FIG. FIG. 3 is an enlarged cross-sectional view of part III shown in FIG. FIG. 4A is a cross-sectional view taken along the line IV-IV shown in FIG. 3, showing the conventional structure. FIG. 4B is a cross-sectional view taken along the line IV-IV shown in FIG. 3, showing the structure of the present embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to the following embodiments. In addition, each direction of up, down, front, back, left, and right shown in the figure is merely defined for convenience of explanation.

FIG. 1 is a plan sectional view showing a schematic configuration of a cylinder block 1 in the fastening structure 100, and FIG. 2 is a sectional view taken along line II-II shown in FIG. Note that FIG. 1 shows a cross section at the height position of the I-I line shown in FIG.

As shown in FIGS. 1 and 2, the fastening structure 100 is a fastening structure in which the cylinder head 2 (shown only in FIG. 2 in this embodiment) is fastened to the cylinder block 1 with bolts 3.

The cylinder block 1 and the cylinder head 2 are components constituting an internal combustion engine. A crankcase 4 is integrally formed in the lower part of the cylinder block 1. The cylinder head 2 is connected to the upper part of the cylinder block 1 and fastened by bolts 3.

The cylinder block 1 includes a plurality of cylinder bores 10 in series (four in the present embodiment, but only two are shown in FIG. 1), a water jacket 20 surrounding the plurality of cylinder bores 10, and a cylinder bore 10. And a bore wall 30 formed between the water jackets 20.

Further, the cylinder block 1 is formed on the jacket wall 40 formed on the outside of the water jacket 20 facing the bore wall 30, the boss portion 50 formed on the jacket wall 40 at the position between the cylinder bores 10, and the boss portion 50. A female screw hole 60, which is formed and into which a bolt 3 is screwed, is provided.

The cylinder bores 10 are arranged side by side in a row in the front-rear direction. The cylinder bore 10 is a space for accommodating a piston (not shown) so as to be able to move up and down, and is formed in a circular cross section in a plan view. The vertical direction of the present embodiment coincides with the direction of the central axis C of the cylinder bore 10.

The water jacket 20 is a passage through which engine cooling water flows inside the cylinder block 1. Further, the water jacket 20 has a long cross-sectional shape in the vertical direction, and is formed from a position near and below the upper surface of the cylinder block 1 to a position near and above the lower surface of the cylinder block 1. The water jacket 20 is formed so as to surround the plurality of cylinder bores 10.

The bore wall 30 is a bore spacing wall formed by integrally connecting a plurality of (two in FIG. 1) cylindrical wall portions 31 arranged side by side in the front-rear direction and adjacent wall portions 31 to each other. It has a part 32 and. The cylinder bore 10 is defined by the inner wall surface of the cylindrical wall portion 31.

The jacket wall 40 is formed in a long frame shape in the front-rear direction in a plan view, and is arranged with a gap between the jacket wall 40 and the bore wall 30. The water jacket 20 is defined by a gap between the bore wall 30 and the jacket wall 40.

The boss portion 50 is formed on the jacket wall 40 located between the adjacent cylinder bores 10 in the cylinder bore 10 row direction (front-rear direction). Further, the boss portion 50 is formed on the jacket walls 40 on both the left and right sides, respectively.

Further, the boss portion 50 is formed so as to project inward in the left-right direction from the jacket wall 40 toward the bore spacing wall portion 32.

The boss portion 50 of the present embodiment is formed in a substantially semicircular cross section in a plan view, and has a female screw hole 60 in the central portion. Further, the boss portion 50 has a front-rear symmetrical cross-sectional shape with the position between the cylinder bores 10 in the front-rear direction (the position that bisects the central axis C of the cylinder bore 10) as the reference position A1.

As shown in FIG. 2, the female screw hole 60 extends in the vertical direction from the upper surface to the lower portion of the cylinder block 1. The lower end 61 of the female screw hole 60 is located higher than the bottom surface 21 of the water jacket 20. In FIG. 1, the female screw hole 60 is at an invisible height position, but is described for convenience so that the position can be understood in a plan view.

The cylinder head 2 is formed with a bolt insertion hole 70 arranged coaxially with the female screw hole 60 of the cylinder block 1. The cylinder head 2 is fastened to the cylinder block 1 by inserting the bolt 3 into the bolt insertion hole 70 from above and screwing it into the female screw hole 60. Reference numeral 80 is a water jacket formed inside the cylinder head 2.

By the way, when the cylinder head 2 is fastened to the cylinder block 1, the boss portion 50 is pulled toward the cylinder head 2 side (upper side) by the bolt 3 around the female screw hole 60.

As a result, on the bottom surface 21 of the water jacket 20, a stress that is pulled upward is generated in the portion adjacent to the boss portion 50.

In particular, in the present embodiment, as shown in FIG. 3, the boss portion 50 is within a predetermined angle range β in which a position deviated from the reference position A1 by a predetermined angle α around the center X of the female screw hole 60 is set as the center position A2. The surface 51 of the above has an arcuate cross-sectional shape protruding from the female screw hole 60 side toward the bore wall 30 side. On the bottom surface 21 of the water jacket 20, stress tends to be concentrated in the region D in the angle range β adjacent to the boss portion 50.

Here, FIGS. 4A and 4B are sectional views of the IV-IV line shown in FIG. 3, FIG. 4A represents a conventional structure, and FIG. 4B represents a structure of the present embodiment. In addition, in FIG. 3, FIG. 4A, and FIG. 4B, only the structure in front of the reference position A1 is shown. The structure behind the reference position A1 has a front-rear symmetrical relationship with the structure in front of the reference position A1, and the same effect can be obtained.

As shown in FIG. 4A, in the case of the conventional structure, the bottom surface 21 of the water jacket 20 is a plane perpendicular to the central axis C of the cylinder bore 10 shown in FIG. 1 (referred to as a horizontal plane for convenience) within the above angle range β. ). In this case, in the region D within this angle range β, stress concentration occurs due to the stress P1 pulled upward in parallel with the central axis C of the cylinder bore 10.

That is, the "predetermined angle range β" referred to in the present embodiment means an angle range in which stress concentration is recognized by a simulation test or the like when the bottom surface 21 is a horizontal plane. Such stress concentration causes fatigue fracture or the like on the bottom surface 21 of the water jacket 20 or the surface 51 of the boss portion 50.

On the other hand, as shown in FIG. 4B, in the present embodiment, the inclined surface 22 is provided on the bottom surface 21 of the water jacket 20 within the above angle range β. Specifically, the inclined surface 22 is formed over the entire region D within the angle range β. Further, the inclined surface 22 is inclined toward the cylinder head 2 side (upper side) as the angle from the start position B on the reference position A1 side increases within the angle range β. The inclined surface 22 is formed on the entire bottom surface 21 within the angle range β, but may be formed only on a part of the bottom surface 21 including the region D.

According to the present embodiment, the stress P1 pulled upward in parallel with the central axis C of the cylinder bore 10 on the surface of the region D located in the angle range β is the stress P2 parallel to the inclined surface 22 and the inclined surface. It is decomposed into the stress P3 perpendicular to 22. As a result, the stress generated in the region D is dispersed, and the stress concentration can be suppressed. Then, fatigue fracture due to stress concentration can be suppressed. Further, this makes it possible to improve the structural strength of the cylinder block 1 and provide an internal combustion engine suitable for a higher compression ratio or the like.

Further, as shown in FIG. 3, in the angle range β, the passage width W1 of the water jacket 20 is formed small at a position where the angle from the start position B is small, and this is formed at a position where the angle from the start position B is large. The passage width W2 is formed large (W2> W1).

As can be seen by comparing FIGS. 3 and 4B, the height position of the bottom surface 21 is formed higher at the position of the large passage width W2 than at the position of the small passage width W1, so that the bottom of the water jacket 20 is formed. The wall portion 23 becomes thick. As a result, the strength of the bottom surface 21 can be secured even at the position of the large passage width W2, and fatigue fracture and the like can be effectively suppressed.

On the other hand, the above-mentioned basic embodiment can be appropriately modified and implemented without departing from the gist of the present disclosure.

For example, as shown in FIG. 2, in the basic embodiment, the height position of the lower end 61 of the female screw hole 60 is higher than the bottom surface 21 of the water jacket 20, but the same height position as the bottom surface 21. , Or it may be lower than that. Further, even if the female screw hole 60 penetrates from the upper surface to the lower surface of the cylinder block 1, the same effect can be obtained.

Although the embodiments of the present disclosure have been described in detail above, the embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications and applications included in the idea of the present disclosure defined by the claims. Examples, equivalents are included in this disclosure. Therefore, this disclosure should not be construed in a limited way and may be applied to any other technique that falls within the scope of the ideas of this disclosure.

This application is based on a Japanese patent application (Japanese Patent Application No. 2019-177390) filed on September 27, 2019, the contents of which are incorporated herein by reference.

The present invention has an effect that stress concentration can be suppressed in a fastening structure in which a cylinder head is fastened to a cylinder block with bolts, and is useful for a fastening structure or the like.

1 Cylinder block 2 Cylinder head 3 Bolt 10 Cylinder bore 20 Water jacket 21 Bottom surface 22 Inclined surface 30 Bore wall 40 Jacket wall 50 Boss part 60 Female screw hole 100 Fastening structure A1 Reference position A2 Center position B Start position α Predetermined angle β Predetermined angle range

Claims

It has a fastening structure in which the cylinder head is fastened to the cylinder block with bolts.
The cylinder block is
With multiple cylinder bores
A water jacket that surrounds the plurality of cylinder bores,
A bore wall formed between the plurality of cylinder bores and the water jacket,
A jacket wall formed on the outside of the water jacket facing the bore wall,
A boss portion formed on the jacket wall at a position between the cylinder bores, which is a position between one cylinder bore of the plurality of cylinder bores and the other cylinder bore of the plurality of cylinder bores.
A female screw hole formed in the boss portion and into which the bolt is screwed is provided.
In a plan view, the bottom surface of the water jacket is provided with an inclined surface within a predetermined angle range centered on a center position deviated by a predetermined angle around the center of the female screw hole with the position between the cylinder bores as a reference position. Fastening structure.
The fastening structure according to claim 1, wherein the inclined surface is inclined toward the cylinder head side as the angle from the start position on the reference position side increases within the angle range.
The passage width of the water jacket is formed in the first width at a position where the angle from the start position is within the predetermined angle within the angle range, and the angle from the start position is larger than the predetermined angle. The fastening structure according to claim 2, wherein the fastening structure is formed in a second width larger than the first width.