JPH0874654A - Cylinder block construction - Google Patents

Abstract

PURPOSE: To fasten a cylinder head to a block main body on each side of the center line of a cylinder bore, while keeping the cylinder bore from deflecting. CONSTITUTION: An exterior wall part 4 is formed on each side of an interior wall part 3 in which a plurality of cylinder bores 6 are provided parallel to each other, and both wall parts 3, 4 are connected together by a deck part 5 to constitute a part of a block main body 2. A first bolt hole 17 into which a first head bolt for fastening a cylinder head is threaded is formed in the side portion of the external wall part 4 between the adjacent cylinder bores 6. A projection 24 is formed on the side portion of the external wall part 4 between the adjacent cylinder bores 6. The side portion has higher rigidity than that portion of the block main body 2 which is on each side of the center line L of the cylinder bore 6 in the external wall part 4. An intermediate member 19 is disposed at the side of the external wall part 4 and connected to the projection 24 by a bolt 26. A second bolt hole 27, into which is threaded a second head bolt 28 for fastening the cylinder head, is formed in the portion of the intermediate member 19 on each side of the center line L.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cylinder block in an engine, and more particularly, to a cylinder having a bolt hole into which a head bolt for fastening a cylinder head is screwed, which is formed on a side of a center line of a cylinder bore. It concerns the block structure.

[0002]

2. Description of the Related Art Conventionally, in a general engine, a cylinder head is fastened on a cylinder block. As one form of this fastening, a structure using six head bolts per cylinder has been proposed in order to cope with the recent increase in engine output (for example, Japanese Utility Model Laid-Open No. 63-19844).
No. 9). As shown in FIGS. 7 and 8A and 8B, the block main body 52 of the cylinder block 51 includes an inner wall portion 54 in which a plurality of cylindrical cylinder bores (cylinders) 53 are arranged side by side and a side portion thereof. An outer wall portion 55 is formed in a state of being separated from the inner wall portion 54, and a deck portion 56 connecting the upper end portions of both wall portions 54, 55. A piston 58 having a piston ring 57 mounted on the outer periphery is housed in the cylinder bore 53 so as to be capable of reciprocating. A space surrounded by the inner wall portion 54, the deck portion 56, and the outer wall portion 55 serves as a water jacket 59 through which cooling water flows.

First bolt holes 61 are formed in both end portions of the outer wall portion 55 in the direction in which the cylinder bores 53 are arranged in parallel, and in the side portions between the adjacent cylinder bores 53 of the outer wall portion 55.
Four bosses 62 each having are formed per cylinder. Further, two bosses 64 each having a second bolt hole 63 are formed in the outer wall portion 55 at a side portion of the center line L of each cylinder bore 53 per cylinder. Thus, both bolt holes 61 and 63 are formed in the outer wall portion 55 of the block body 52.

According to this structure, when the cylinder head 65 is fastened to the block body 52, the cylinder head 6
The first head bolt 66 that is inserted through 5 is the first bolt hole 6
It is screwed into 1. Similarly, the second head bolt 67 inserted into the cylinder head 65 is screwed into the second bolt hole 63.

[0005]

However, in the above-mentioned prior art, the second head bolt 67 is formed in the second bolt hole 63.
When the cylinder head 65 is tightened to the block body 52 by screwing in, the portion of the inner wall portion 54 near the bolt hole 63 is moved to the cylinder bore 5 as shown by the chain double-dashed line in FIG.
It is easy to dent inward of 3.

More specifically, the rigidity of the side portion of the center line L in the inner wall portion 54 is lower than the rigidity of the side portion between the adjacent cylinder bores 53. This means that while the portion between the adjacent cylinder bores 53 in the inner wall portion 54 has a sufficient thickness, the side portion of the center line L in the inner wall portion 54 has the bore 53 and the water jacket 59. It is sandwiched between and has a small wall thickness. Therefore, the six bolt holes 61 around the cylinder bore 53,
When the head bolts 66 and 67 are tightened at 63, the portion near the second bolt hole 63 corresponding to the low rigidity portion is lifted by the stress associated with the tightening. In addition, this stress is transmitted to the inner wall portion 54 via the deck portion 56.
Of the inner wall portion 54, the side portion of the center line L of the inner wall portion 54 is recessed inward of the cylinder bore 53, and the bore 53 is distorted.

When the cylinder bore 53 is thus distorted, the oil scraping performance of the piston ring 57 of the piston 58 is deteriorated and the engine oil consumption is increased. There is also a problem that the amount of wear of the piston ring 57 and the piston 58 increases.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to prevent a cylinder bore from being distorted and to fasten a cylinder head to a block main body by a head bolt at a side of a center line of the cylinder bore. It is to provide a cylinder block structure.

[0009]

In order to achieve the above object, the present invention forms an outer wall portion on a side of an inner wall portion in which a plurality of cylinder bores are juxtaposed in a state of being separated from the inner wall portion, and A part of the block main body is formed by connecting the inner wall portion and the outer wall portion of the above with a deck portion, and a first head bolt for fastening a cylinder head is screwed on a side portion between adjacent cylinder bores in the outer wall portion. A first bolt hole to be inserted is formed, and on the side of the center line of the cylinder bore,
A cylinder block structure having a second bolt hole into which a second head bolt for fastening a cylinder head is formed, wherein an intermediate member is arranged laterally of an outer wall portion of the block body, and the intermediate member is provided with the first member. Two bolt holes are formed, and the intermediate member is connected to a portion of the outer wall portion of the block body having a rigidity higher than a side portion of the center line.

[0010]

When the cylinder head is fastened to the block body, the first head bolt is screwed into the first bolt hole and the second head bolt is screwed into the second bolt hole. The location where the first bolt hole is formed is a lateral portion between the adjacent cylinder bores in the outer wall portion. Since the rigidity between the cylinder bores is especially high among the inner wall portions, the rigidity is also high at the portion connected to this portion via the deck portion (in the vicinity of the first bolt hole). In addition, the second bolt hole is formed in an intermediate member that is arranged on the side of the outer wall portion of the block body and is separate from the block body. The intermediate member is connected to a portion of the block body having a higher rigidity than a side portion of the outer wall portion of the center line. Therefore, the location where the second bolt hole is formed also has high rigidity.

As described above, the rigidity is high at the places where the first bolt holes and the second bolt holes are formed. Therefore, when the cylinder head is fastened to the block body by the first head bolt and the second head bolt,
The vicinity of the second bolt hole in the intermediate member is unlikely to be lifted to the cylinder head side due to the stress associated with tightening. At this time, even if the same portion is slightly lifted, the intermediate member is formed of a member different from the block body, so that the stress is hard to be transmitted to the deck portion or the inner wall portion, and the influence on the cylinder bore is avoided. . as a result,
The cylinder head is fastened to the block body without distorting the cylinder bore.

When the cylinder block having such a structure is incorporated in an engine and the engine is operated, the piston reciprocates in a cylinder bore having a proper shape with less distortion. At the time of this reciprocating movement, a gap due to the strain is not generated between the piston ring mounted on the outer circumference of the piston and the cylinder bore, and unnecessary stress due to the strain is not applied to the piston ring and the cylinder bore.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a cylinder block for a 4-cylinder engine will be described below with reference to FIGS.

As shown in FIGS. 1 and 3, the block main body 2 which constitutes most of the cylinder block 1 is provided with an inner wall portion 3, an outer wall portion 4 and a deck portion 5. On the inner wall portion 3, four cylinder bores (cylinders) 6 having a cylindrical shape are arranged side by side in a state of being separated from each other. A piston 7 is reciprocally housed in each cylinder bore 6. The space inside each cylinder bore 6 is partitioned by each piston 7 into a combustion chamber 8 above the piston 7 and a crank chamber 9 below.

Three piston rings 11, 12, 13 are mounted on the outer periphery of the upper portion of each piston 7. Of the piston rings 11 to 13, the central portion and the rings 12 and 11 above the central portion prevent the gas (fuel mixture of air and fuel or combustion gas) in the combustion chamber 8 from leaking to the crank chamber 9. It is a compression ring for. Further, the lowermost piston ring 13 is an oil ring for scraping off excess engine oil adhering to the wall surface of the cylinder bore 6 in order to prevent it from entering the combustion chamber 8.

Each outer wall portion 4 is laterally spaced from the inner wall portion 3. The deck portion 5 connects between the upper end portions of the inner wall portion 3 and the outer wall portion 4. A space surrounded by the inner wall portion 3, the outer wall portion 4, and the deck portion 5 serves as a water jacket 14 through which cooling water for cooling the engine flows. Then, the cylinder head 15 is fastened on the inner and outer both wall portions 3 and 4 and the deck portion 5.

As shown in FIGS. 1 and 2, bosses 16 are formed on both end portions of the outer wall portion 4 in the direction in which the cylinder bores 6 are arranged in parallel, and on the side portions between adjacent cylinder bores 6 of the outer wall portion 4, Here is the center line L of the cylinder bore 6.
A first bolt hole 17 is bored along. That is, there are four first bolt holes 17 for each cylinder bore 6.
They are opened one by one. Then, the first head bolt 18 for fastening the cylinder head is screwed into each of the first bolt holes 17 from above.

A pair of intermediate members 19 are connected near the sides of the outer wall portion 4, respectively. More specifically, as shown in FIGS. 2 and 4, each intermediate member 19 has a cylinder bore 6
The main body 21 has an elongated shape extending in the juxtaposed direction, and a plurality of legs 22 hang from the main body 21 at predetermined intervals. Each leg 22 is provided with a bolt insertion hole 23 extending in a direction orthogonal to the center line L (left-right direction in FIG. 2). Protrusions 24 are provided laterally at the portions of the outer wall portion 4 where the bosses 16 are formed, and bolt holes 25 are formed in the protrusions 24. The rigidity of the portion where these protrusions 24 are provided is the rigidity of the side portion of the outer wall portion 4 of the block body 2 that is on the center line L of the cylinder bore 6 (the portion where the second bolt hole 63 is formed in the prior art). Is higher than. Bolt 26 as a connecting member
Is inserted into each bolt insertion hole 23, and the corresponding bolt hole 2
It is screwed into 5. The intermediate member 19 is firmly fastened to the protrusion 24 by this screwing.

As shown in FIG. 3, in each intermediate member 19, a second bolt hole 27 is formed in a side portion of each center line L along the center line L. That is, two second bolt holes 27 are drilled for each cylinder bore 6. Then, the second head bolt 28 for fastening the cylinder head is screwed into each of the second bolt holes 27 from above.

In this embodiment having such a structure, when the cylinder head 15 is fastened to the block body 2, the first head bolts 18 are screwed into the respective first bolt holes 17 and the second bolt holes 27 are inserted into the respective second bolt holes 27. The second head bolt 28 is screwed in. The location where each first bolt hole 17 is opened is the outer wall portion 4
Is a lateral portion between adjacent cylinder bores 6.
Since the rigidity between the cylinder bores 6 is particularly high in the inner wall portion 3, a portion connected to this portion via the deck portion 5 (first
The rigidity is also high in the vicinity of the bolt hole 17). Also,
The second bolt hole 27 is formed in the intermediate member 19 which is arranged near the lateral side of the outer wall portion 4 and is separate from the block body 2. The intermediate member 19 is firmly connected to a portion of the block body 2 having a higher rigidity than the side portion of the outer wall portion 4 of the center line L. Therefore, the rigidity of the intermediate member 19 is also high in the portion where the second bolt hole 27 is formed.

As described above, the rigidity is high at the places where the first bolt holes 17 and the second bolt holes 27 are formed. Unlike the prior art, there is no part where the rigidity is extremely low. Therefore, when the cylinder head 15 is fastened to the block body 2 by both head bolts 18 and 28, the vicinity of the second bolt hole 27 in the intermediate member 19 moves upward (to the cylinder head 15 side) due to the stress associated with the tightening. It is difficult to lift. At this time, even if the same portion is slightly lifted, since the intermediate member 19 is formed by a member different from the block body 2, the stress is hard to be transmitted to the deck portion 5 and the inner wall portion 3, and the stress is not transmitted to the cylinder bore 6. Impact is avoided. As a result, the cylinder head 15 is fastened to the block body 2 without distorting the cylinder bore 6.

When the cylinder block 1 having such a structure is incorporated in an engine and the engine is operated, the piston 7 reciprocates within the cylinder bore 6 having a proper shape with less distortion. At the time of this reciprocating movement, a gap due to the distortion is generated between the piston rings 11 to 13 mounted on the outer circumference of the piston 7 and the cylinder bore 6, or unnecessary distortion due to the distortion is generated in the piston rings 11 to 13 and the cylinder bore 6. No stress is applied. As a result, it is possible to prevent the oil scraping performance from being deteriorated by the piston ring (oil ring) 13 of the piston 7 and prevent an increase in the amount of engine oil consumed. Also, the piston rings 11 to 1
3. Consequently, unnecessary wear of the piston 7 can be suppressed.

Further, according to this embodiment, the following effects are also obtained. If the intermediate member 19 and the bolts 26 are omitted from the cylinder block structure in the present embodiment, the second bolt holes 27 are eliminated, so that the block main body 2 is cylinderd with four head bolts (first head bolts 18) per cylinder. It can be applied to an engine of a type in which the head 15 is fastened. In other words, this block body 2
For an engine that uses four head bolts per cylinder (only the first head bolt 18), six head bolts per cylinder (four first head bolts 1
It can also be used in engines of the type using eight and two second head bolts 28). When the block body 2 is used in the latter engine, it is only necessary to connect the intermediate member 19 to the block body 2 by the bolt 26.
Therefore, if the block main body 2 of the present embodiment is used, it is possible to deal with two types of engines with a simple work.

Further, the second bolt hole 63 is formed in the block body 5
In the prior art of No. 2, the boss 64 is required for the perforation. If these bosses 64 are provided, there will be a portion that projects laterally beyond a portion that is not provided. When this conventional block body 52 is processed or transported on the same production line as the block body without the second bolt holes 63, the projecting portion causes the block body and other members to collide with each other and interfere with each other. There is a risk. In order to avoid this inconvenience, it may be necessary to significantly improve the production equipment.

On the other hand, in this embodiment, the second bolt hole 2
Since 7 is opened in the intermediate member 19 different from the block main body 2, the outer wall portion 4 is prevented from protruding by the bolt hole 27. Therefore, the interference with other members of the block body 2 is eliminated, and it is only necessary to add equipment for attaching the intermediate member 19 to the block body 2. For this reason,
Both types of engines can be processed and transported on the same production line without major improvements to production equipment.

Further, in this embodiment, a plurality of leg portions 22 are hung from the main body portion 21 and the bolt insertion holes 23 are formed therein. That is, the leg portions 22 are provided only in the necessary portions of the bolt insertion holes 23. Therefore, as compared with the case where the adjacent leg portions 22 are filled with the same material in FIG. 4, the intermediate member 19 is formed of a small amount of material, and the weight increase due to the addition of the intermediate member 19 can be reduced.

The present invention can be embodied in another embodiment shown below. (1) As shown in FIG. 5, the protrusion 24 is formed on the lower portion of the boss 16 and the intermediate member 19 is connected to the protrusion 24.
On the outer surface of the block body 2, the water jacket 14
It is also possible to adopt a structure in which the projection 29 is formed in the lower portion of and the intermediate member 19 is connected thereto. The portion where the protrusion 29 is formed has a sufficiently large wall thickness and high rigidity. When changing the connection position in this way, a bolt hole 31 is opened in the protrusion 29, and the bolt 26 inserted into the bolt insertion hole 23 of the intermediate member 19 is screwed into the bolt hole 31.

By doing so, the rigidity in the vicinity of the protrusion 24 is particularly high, so that the intermediate member 19 can be firmly connected to the block body 2. Therefore, it is possible to prevent the intermediate member 19 from being lifted or deformed by the tightening of the second head bolt 28, and to reduce the amount of distortion of the cylinder bore 6.

(2) The intermediate member 19 in the above embodiment may be divided into a plurality of divided pieces, and each divided piece may be connected to the block body 2. (3) The leg portion 22 is omitted, and the intermediate member 19 is formed only by the elongated main body portion 21. Between the second bolt holes 27 adjacent to each other in the main body portion 21 (a portion corresponding to the protrusion 24).
The bolt insertion hole 23 may be formed in the.

(4) In addition to the modification of the above (3), as shown in FIG. 6, in the intermediate member 19, the portion 33 between the adjacent second bolt holes 27 is changed from the portion 32 in which the same bolt hole 27 is formed. Alternatively, the intermediate member 19 may be connected to the block body 2 at this portion 33. By doing so, the amount of protrusion of the bolt 26 from the side surface of the intermediate member 19 can be reduced, and the expansion of the width of the cylinder block 1 due to the addition of the intermediate member 19 and the bolt 26 can be reduced.

(5) In the above-described embodiment, the bolt 26 is applied from the side.
The intermediate member 19 was fastened to the block body 2 by
You may fasten from other directions. For example, in FIGS. 2 and / or 5, the protrusions 24 and 29 are extended to the right, and the intermediate member 19 is placed on the extended portion. Protrusions 24, 29
A bolt insertion hole extending in a substantially vertical direction is provided through the intermediate member 19 and a bolt hole extending in the same direction is formed in the intermediate member 19.
Then, the bolt 26 is inserted into the bolt insertion hole and screwed into the bolt hole, so that the intermediate member 19 is projected onto the projection 24,
Tighten to 29.

Although the respective embodiments of the present invention have been described above, technical ideas other than the claims which can be understood from the respective embodiments will be described below together with their effects. (A) The cylinder block structure according to claim 1, wherein the intermediate member is connected to a lateral portion between adjacent cylinder bores in the outer wall portion. Since this side portion has high rigidity, the intermediate member can be firmly connected to the block body by adopting such a configuration. Therefore, it is possible to prevent the intermediate member from being lifted or deformed by tightening the second head bolt.

(B) In the cylinder block structure according to claim 1, a water jacket which allows passage of cooling water is formed by the inner wall portion, the outer wall portion and the deck portion, and the intermediate member is a water jacket in the block body. Cylinder block structure connected to a position away from the jacket. Since this portion has high rigidity, the intermediate member can be firmly connected to the block body by adopting such a configuration. Therefore, it is possible to prevent the intermediate member from being lifted or deformed by tightening the second head bolt.

(C) In the cylinder block structure according to claim 1, the above (a) or (b), the intermediate member includes a main body portion extending along a direction in which the cylinder bores are arranged in parallel.
A cylinder block structure comprising: a leg portion protruding from the main body portion along the center line of the cylinder bore, and an intermediate member is connected to the block main body at the leg portion. With this configuration, the intermediate member can be formed of a small amount of material, and an increase in weight due to the addition of the intermediate member can be reduced, as compared with the case where adjacent leg portions are filled with the same material.

(D) In the cylinder block structure according to claim 1, the above (a) or (b), the portion between the adjacent second bolt holes of the intermediate member is the second bolt hole. A cylinder block structure that is formed thinner than the opened portion, and the intermediate member is connected to the block main body by a connecting member in the thin portion. With such a configuration, the amount of protrusion of the connecting member from the intermediate member can be reduced, and the expansion of the width of the cylinder block accompanying the addition of the intermediate member and the connecting member can be reduced.

In the present specification, members relating to the constitution of the invention are defined as follows. (A) The structure for connecting the intermediate member 19 to the block main body 2 is not limited to the structure in which the intermediate member 19 is tightened by the bolt 26, but also a structure in which a hole is formed in the intermediate member 19 and the projection 24 is press-fitted therein, The structure includes a structure in which a recess is formed in the block body 2 and a protrusion is formed in the intermediate member 19, and the protrusion is press-fitted into the recess, a structure in which a dedicated fastener is used for connection, and further caulking.

[0037]

As described above in detail, according to the present invention, the intermediate member is arranged on the side of the outer wall portion of the block body, and is more rigid than the side portion of the outer wall portion of the block body on the center line of the cylinder bore. The intermediate member is connected to the high part of. Then, in the intermediate member, a second bolt hole into which a second head bolt for fastening the cylinder head is screwed is formed in a side portion of the center line of the cylinder bore.

Therefore, even in a cylinder block of the type in which the cylinder head is fastened at the side portions between the adjacent cylinder bores and the side portions of the center line of the cylinder bore, the block body is deformed due to the tightening of the head bolt. Therefore, it is possible to suppress the distortion of the cylinder bore.

If the cylinder block having the above-mentioned structure is incorporated in an engine and the piston is reciprocated in the cylinder bore, a problem caused by the distortion of the cylinder bore, for example, deterioration of oil scraping performance by the piston ring, or piston ring. It is possible to eliminate unnecessary wear of the piston and the like.

[Brief description of drawings]

FIG. 1 is a plan view of a cylinder block structure in an embodiment embodying the present invention.

FIG. 2 is an enlarged sectional view taken along line AA of FIG.

FIG. 3 is an enlarged sectional view taken along line BB of FIG.

FIG. 4 is a side view of the intermediate member.

FIG. 5 is a partial cross-sectional view showing another example in which an intermediate member is connected to a portion below the water jacket on the outer surface of the block body.

FIG. 6 is a plan view showing another example in which each intermediate member is formed with a small-thickness portion and the intermediate member is connected to the block main body at this portion.

FIG. 7 is a plan view showing a conventional cylinder block structure.

8 (a) is an enlarged cross-sectional view taken along line CC of FIG.
7B is an enlarged cross-sectional view taken along the line DD of FIG. 7.

[Explanation of symbols]

1 ... Cylinder block, 2 ... Block body, 3 ... Inner wall part, 4 ... Outer wall part, 5 ... Deck part, 6 ... Cylinder bore, 1
7 ... 1st bolt hole, 18 ... 1st head bolt, 19 ... Intermediate member, 27 ... 2nd bolt hole, 28 ... 2nd head bolt, L ... Center line.

Claims (1)

[Claims] 1. An outer wall portion is formed on a side of an inner wall portion in which a plurality of cylinder bores are juxtaposed in a state of being separated from the inner wall portion,
A part of the block main body is formed by connecting the inner wall portion and the outer wall portion with a deck portion, and a first head bolt for fastening a cylinder head is provided on a side portion between adjacent cylinder bores in the outer wall portion. Is a cylinder block structure in which a second bolt hole into which a second head bolt for fastening a cylinder head is screwed is formed on the side of the center line of the cylinder bore. Then, an intermediate member is arranged on the side of the outer wall portion of the block body,
While forming the second bolt hole in this intermediate member,
A cylinder block structure in which the intermediate member is connected to a portion of the block body having a rigidity higher than a side portion of the outer wall portion of the center line.