JP3127162B2 - Engine block structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an engine block structure.

[0002]

2. Description of the Related Art Regarding the block structure of an engine,
Japanese Patent Application Laid-Open No. 2-108612 discloses that a scut portion of a cylinder block and a side portion of a bearing cap for supporting a crankshaft housed in the scut portion are fixed by bolts to increase the support rigidity of the crankshaft. There are disclosures of techniques that have been enhanced. Further, this publication discloses that the lower end surfaces of the bearing caps are connected by a beam made of a separate member.

[0003] On the other hand, today, attention has been paid to lightening of the engine, and the so-called short skirt is called the short skirt.
It is known to shorten the length of the girth portion and fasten a lower block made of, for example, aluminum to the lower end of the cylinder block body to form a crank chamber with the lower block. However, the lower block is conventionally
It is positioned as a member supporting the mission,
For this reason, the technology development is being studied from the standpoint of securing rigidity against power plant bending exclusively. To solve the problem of power plant bending, the rear end of the lower block faces the rear end. It is known that the rear end face is used as a transmission mounting surface as a shape gradually bulging outward in accordance with the following.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a block structure of an engine in which a lower block is used to improve the support rigidity of a bearing cap on the premise of an engine having a lower block. It is in.

[0005]

According to the present invention, there is provided a cylinder block having a cylinder bore having a skirt portion and a lower block fastened to a lower end of the skirt portion. A crank chamber for accommodating a crankshaft is formed, and a rear end of the lower block is gradually swelled outward toward the rear end, and a rear end surface formed by a rear end wall of the lower block is a transmission. In the engine block structure having the mounting surface, an oil pan mounting seat is provided at a lower end of the lower block,
The lower block is formed slightly forward of the rear end, and the lower block has a partition wall extending between both side walls of the lower block and partitioning an inner space of the lower block back and forth. A plurality of pans are formed in the front-rear direction so as to be present behind the rear end of the pan mounting seat, and a rear end wall of the lower block and a rear end of the mounting pan of the oil pan are spaced at a predetermined interval. The lower block is connected via a pair of ribs that bulge downward toward the rear end wall of the lower block. A reinforcing rib is formed to be open, and provided on the outer side in the arrangement direction of the pair of ribs for connecting a rear end wall of the lower block and a rear end of a mounting seat of the oil pan, Multiple dividers A partition wall on a rear side of a rear end of the mounting seat of the oil pan, at least one partition wall on a front side of a rear end of the mounting seat of the oil pan, and a rear end wall of the lower block. A bolt insertion hole penetrating in a vertical direction is formed, and a lower portion of a bearing cap supporting a crankshaft is fixed to the lower block by a bolt inserted into each of the bolt insertion holes. The lower end opening position of each bolt insertion hole of the partition wall on the rear side of the rear end of the seat and the rear end wall of the lower block is located in the recess, and the length dimensions of all the bolt insertion holes are the same. Is set as follows.

[0006]

According to the present invention, since the bearing cap is fixed to the partition wall and the rear end wall of the lower block,
The support rigidity of the bearing cap can be improved. The rear end wall of the lower block, to which the heavy transmission is directly attached, is formed by a pair of ribs, the rear end wall of the lower block, and the oil pan mounting seat formed by the oil pan mounting seat. Is linked to
It is possible to effectively increase the rigidity of the rear end wall of the lower block, and from this point, it is possible to further increase the supporting rigidity of the bearing cap.

Further, a pair of ribs are connected to the rear end wall of the lower block and the oil pan mounting seat so as to swell downward toward the rear end wall of the lower block, thereby forming a concave portion. By utilizing the inside of the recess, the height of the lower end opening of each bolt insertion hole of the partition wall and the rear end wall of the lower block behind the rear end of the oil pan mounting seat can be adjusted (opened from the bottom of the recess). Adjust the length of the bolt insertion hole (substantially the length of the bolt used for fastening) in the wall and the rear end wall of the lower block by inserting each of the other partition walls on the front side with respect to the rear end of the oil pan mounting seat. It can be made equal to the length dimension of the hole. For this reason, the length dimensions of all bolts used for each bolt insertion hole of each partition wall and the rear end wall of the lower block are unified under a short length dimension, and each bolt in each support portion of the bearing cap is The support stiffness is increased in a uniform state (equal support), and the bending force acting on the crankshaft can be effectively dealt with.

In addition, the rear end wall of the lower block has a pair of ribs, a rear end wall of the lower block, and a closed cross-sectional structure formed by a mounting seat of the oil pan. By being connected to the seat, it is possible to further increase the rigidity of the rear end wall of the lower block.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes an engine body. The engine body 1 is a four-cycle reciprocating four-cylinder engine. A piston (not shown) is slidably inserted into a bore 2a of a cylinder block body 2. The reciprocating motion of the piston is transmitted to the crankshaft 4 via the connecting rod 3 and converted into a rotational motion.

The cylinder block body 2 is made of cast iron, and the skirt portion 2b forming the crank chamber 5 is a so-called short skirt, and the height of the lower end of the skirt portion 2b is substantially equal to that of the skirt portion. The height is set at the rotation center 4a of the crankshaft 4. A lower block 6 is disposed at the lower end of the skirt portion 2b. The skirt portion 2b and the lower block 6 cooperate to form a substantial crank chamber 5, and the lower block 6 Oil pan 7 at the bottom
The lower block 6 and the oil pan 7 are fastened together by bolts 8. That is, the bolt 8 is inserted from the oil pan 7 side, and the lower block 6
And is fixed to (the lower end flange of) the cylinder block 2. The size of the oil pan 7 will be described later.

The lower block 6 will be described in detail with reference to FIGS. In this embodiment, the lower block 6 is made of aluminum (Al) to reduce its weight. The rear end 6a of the lower block 6 is gradually swelled downward and laterally toward the rear, so that a transmission (not shown) is attached to the rear end face 6b.

As shown in FIG. 2, the inner space of the lower block 6 has four partition walls 9 spaced from the front side to the rear side (from right to left in FIG. 2).
, The space between the first partition wall 9 and the second partition wall 10 is defined as a crank space NO1 for the most cylinder,
The space between the second partition wall 10 and the third partition wall 11 is a crank space NO2 for the second cylinder, and the space between the third partition wall 11 and the fourth partition wall 12 is the crank space NO2 for the third cylinder. A space NO3 is provided, and a space between the fourth partition wall 12 and the rear end wall 6c of the lower block 6 is a crank space NO4 for the fourth cylinder (the left side in FIG. 2). The partition walls 9 to 12 are connected to each other by a partition wall plate portion 13, and a rib 1 is provided between the first partition wall 9 and the front end wall 6d of the lower block 6.
4, the space between the fourth partition wall 14 and the rear end wall 6c of the lower block 6 is connected by the bottom plate 6f of the lower block 6, and the partition walls 9 to 14 are formed by these elements 13, 14 and the like. 12 are suppressed.

The plate 13 between the partition walls is provided with an oil return hole as shown by reference numeral 13a in FIG. 2, and passes through the oil return hole 13a to be the first to third cylinder. Oil in the cylinder crank spaces NO1 to NO3 is returned to the oil pan 7. An opening 13b is formed in the plate 13, and the opening 13b communicates the crank spaces NO1 to NO3 for the first to third cylinders with the space in the oil pan 7. This opening 13b
Are provided on both sides of the lower block 6 (both sides of the plate 13), and the crank spaces NO1 to NO3 of the first to third cylinders are provided.
The mist-like oil in the NO 3 is returned to the space inside the oil pan 7 through the opening 13b.

That is, as the pistons of the first to third cylinders descend, the air in the crank spaces NO1 to NO3 is pushed out to the space in the oil pan 7, and along with the movement of the air in the crank space, ~ Crank space of the third cylinder
Mist oil in NO1 to NO3 is returned to the space in the oil pan 7. The oil stored in the oil pan 7 is pumped by an oil pump (not shown), and the pumped oil is guided to each sliding portion. In FIG. 2, reference numeral 15 denotes an oil strainer, and the oil purified by the oil strainer 15 is guided to the oil pump through an oil feed pipe 16.

The length of the oil pan 7 in the longitudinal direction is from the front end of the lower block 6 to the third cylinder NO3 in relation to the transmission mounting portion 6b formed at the rear end of the lower block 6. Accordingly, as shown in FIG. 5, the seat 6g for mounting the oil pan of the lower block 6 has its rear end located in front of the third partition wall 11 close to the third partition wall 11. The rear end of the lower block 6 (the above-described downwardly and laterally swelling portion) is a portion where the fourth cylinder is located.

The partition walls 9, 1 excluding the third partition wall 11
As shown in FIGS. 2 to 5, a bolt insertion hole 18 extending in the vertical direction is formed at the center of the rear end wall 6c of the lower block 6 in the longitudinal direction. Two partition walls 9, 10, 12 and two rear end walls 6c are provided at intervals in the longitudinal direction.

A bolt 19 is inserted into the bolt insertion hole 18 from below, and the tip of the bolt 19 is screwed into a screw hole (not shown) formed in the lower surface of the bearing cap 20. The lower block 6 and the bearing cap 20 are integrated by the bolt 19 on the inner side of the bolt 20b for fastening the bearing cap 20 and a bearing (not shown) of the cylinder block body 2. As is known, the bearing cap 20 constitutes a part (lower half) of the bearing portion of the crankshaft 4.
Is usually made of cast iron.

The first of the bearing caps 20 is
The bearing cap 20A disposed on the partition wall 9, the third partition wall 11, and the rear end wall 6c of the lower block 6
Its side is integrated with the lower block 6.

That is, the first partition wall 9 and the third partition wall 11
As shown in FIG. 3, a lateral through hole 21 is formed in the rear end wall 6c and opens in the side wall 6e of the lower block 6 and extends in the left-right direction. A slide bush 22 is fitted into the lateral through hole 21. Has been inserted. On the other hand, the bearing cap 20A (the bearing cap 20 provided on the first and third partition walls 9, 11 and the rear end wall 6c of the lower block 6) has a boss portion projecting outward on a side portion thereof. 20
a, and a screw hole (not shown) is formed in the boss portion 20a.
Are formed. Then, the slide bush 22
The tip of the bolt 23 inserted in the boss portion 20a
The side wall 6e of the lower block 6 and the side of the bearing cap 20 are integrated with each other.

In other words, the bearing cap 20 disposed corresponding to the first and third partition walls 9 and 11 and the rear end wall 6c has a side portion integrated with the lower block 6, and The lower part of the bearing cap 20 disposed on the first partition wall 9 and the rear end wall 6c is also fixed to the lower block 6). On the other hand, the second and fourth
As shown in FIG. 4, the bearing cap 20A provided corresponding to the partition walls 10 and 12 does not have the boss portion 20a formed on its side, and only the lower portion is It is integrated.

With the above configuration, the bearing cap 2
Since the reference numeral 0 is fixed to the lower block 6, the support rigidity of the bearing cap 20 can be improved without using a separate beam as in the prior art. In particular, in the bearing cap 20 with a boss,
Since the side portion is fixed to the lower block 6 and is pressed from the side by the lower block 6, it is possible to prevent the bearing cap 20 from cracking. In particular, the lower part of the bearing cap 20 provided on the first partition wall 9 and the rear end wall 6c is also integrated with the lower block 6, and the lower block 20 presses down from below. As a result, the occurrence of cracks in the bearing cap 20 can be more effectively prevented.

Since the slide bush 22 is interposed for fixing the side portion of the bearing cap 20, the slide bush 22 can absorb a dimensional error of the bearing cap 20 and the like. There is no loss of sex.

A space 25 formed between the bossed bearing cap 20 and the partition wall 9 and the like (hereinafter referred to as a bossed space; see FIG. 3) and a space between the bossless bearing cap 20A and the partition wall 10 and the like. The space 26 formed by
(Hereinafter referred to as a boss-free space; see FIG. 4), the boss-free space 26 is at least the boss portion 2.
Since the space 0a does not exist, the space is larger than the space 25 with the boss.

The difference in size between the bossed space 25 and the bossless space 26 means the following. As described above, the second partition wall 10 on which the bossless bearing cap 20A is disposed partitions between the crank space NO1 for the first cylinder and the crank space NO2 for the second cylinder. Therefore, the boss-free space 26 constitutes a communicating portion that communicates between the crank spaces NO1 and NO2. Similarly, the bossless space 2 of the fourth partition wall 12
Numeral 6 constitutes a communicating part which communicates between the third cylinder crank space NO3 and the fourth cylinder crank space NO4. On the other hand, the space 2 with the boss of the third partition 11
Reference numeral 5 designates a communicating portion which communicates between the crank space NO2 for the second cylinder and the crank space NO3 for the third cylinder. The NO2-NO3 communicating portion 25 includes the NO1-NO2 and NO3- The passage effective area is smaller than that of the NO4 communication portion 26.

By the way, when the ignition order of the engine body 1 is indicated by the cylinder number, NO1 (first cylinder) -NO3 (third cylinder) -NO4 (fourth cylinder) -NO2 (second cylinder) Cylinder). Therefore, the piston of the first cylinder NO1 and the piston of the fourth cylinder are in the same direction (for example, ascending).
, The piston of the second cylinder NO2 and the piston of the third cylinder NO3 move in the same direction (for example, descend). In other words, the pistons of the first cylinder NO1 and the second cylinder NO2, and the third cylinder NO3 and the fourth cylinder NO4 sandwiching the bossless communication portion 26 having the large passage effective area have the pistons move in opposite directions. On the other hand, the pistons of the second cylinder NO2 and the third cylinder NO3 sandwiching the communication portion 25 with the boss having a small effective passage area move in the same direction.

Therefore, for example, the air in the second and third crank spaces NO2 and NO3 passes through the communicating portion 26 having a large effective passage area as the pistons of the corresponding cylinders descend, and the air in the second and third crank spaces NO2 and NO3 passes through. The air in the third space NO2 (air for the stroke of the piston) smoothly moves to the first space NO1 (the piston moves up), and the air in the third space NO3 moves to the fourth space NO4 (the piston (Ascending movement). Therefore, the upward movement or the downward movement of the piston is not hindered by the air in the crank space, and the negative work (pumping loss) caused by the air in the crank space hindering the movement of the piston is reduced. can do.

In particular, the crank space NO4 for the fourth cylinder is
As described above, since the opening is defined by the bottom plate portion 6f of the lower block 6 and is not directly communicated with the space inside the oil pan 7 (like the other crank space NO3, the opening communicating with the oil pan 7). Since the portion 13b does not exist), the fourth cylinder crank space NO4 is communicated with the third cylinder crank space NO3 through the large communication portion 26, thereby forming the fourth cylinder NO4. Pumping loss can be reduced.

FIG. 6 shows the lower block 6 viewed from the side. The side wall 6e of the lower block 6
It is formed of pillars 31 and ribs 32 arranged side by side at intervals. Then, bolts 8 for fastening the lower block 6 and the cylinder block body 2 to the column 31 are provided.
Insertion holes are formed. The ribs 32 are arranged in a cross shape to increase the torsional rigidity of the lower block 6. In the thin plate portion 30, the thin plate portion 30 is not provided in the portion 33 facing the crank space NO3 of the third cylinder and the portion 34 facing the crank space NO4 of the fourth cylinder. That is, the portions 33 and 34 are open portions opened to the side of the lower block 6.

The open portions 33 and 34 are
In order not to impair the communication relationship between the lower block 3 and the lower block 6, the lower block 6 is covered by a plate member 35, for example. That is, the plate member 35 is fixed to the side wall 6e of the lower block 6 using a bolt (not shown). The bolt is screwed into a screw hole (formed on the side wall 6e of the lower block 6) indicated by reference numeral 36 in FIG.

With the above configuration, the third cylinder crank space NO3 and the fourth cylinder crank space NO4 are formed on the sides of the lower block 6 by the plate members 35 passing through the open portions 33 and 34. Are communicated with each other through the passage. Thereby, regarding the fourth cylinder NO4, it is possible to further reduce the pumping loss of the fourth cylinder together with the communication part 26.

The open portions 33, 34 and the plate member 35 may be provided only on one side wall 6e of the lower block 6, or may be provided on both sides 6e of the lower block 6,
6e. Further, the plate member 35 also functions as a reinforcing member for the lower block 6 (improving the bending rigidity of the lower block 6). Such a reinforcing function can be easily adjusted by changing the material or plate thickness of the plate member 35, or can be adjusted by forming a bead on the plate member 35. It is.

Referring to FIGS. 5 and 7, lower block 6 will be described.
The rear end 6a will be described. As described above, the rear end 6a of the lower block 6 has a shape that bulges laterally and downward from the fourth partition wall 12 toward the rear end 6b of the lower block 6. The swelling shape at the rear end 6a of the lower block 6 ensures the rigidity of the lower block 6 (cylinder block 2) including the transmission with respect to power plant bending.

The rear end 6a of the lower block 6
In each of the lower portions, a plurality of ribs 40 are formed on both sides of the lower portion to connect between the oil pan mounting seat 6g and the rear end wall 6c of the lower block 6. Further, a concave portion 41 opening downward is formed in a central portion sandwiched between the portions (the above both side portions) where the ribs 40 are formed, and the concave portion 41 and the side where the ribs 40 are formed are formed. The portion is partitioned by a second rib 42 extending between the oil pan mounting seat 6g and the rear end wall 6c of the lower block 6. The length of the bolt insertion hole 18 formed in the fourth partition wall 12 and the rear end wall 6c of the lower block 6 is reduced by the recess 41 so that the bolt insertion hole 18 formed in the other partition wall 11 or the like is inserted. The length of the hole 18 is the same as that of the hole 18.

With the above configuration at the rear end 6a of the lower block 6, first, the ribs 40 and 41
Rear end wall 6 of lower block 6 to which the mission is attached
c is connected to the fourth partition wall 12 in a rigid relationship. Accordingly, the rigidity of the rear end wall 6c of the lower block 6, which is directly affected by the power plant, is increased, and the suppression of the power plant bending or the generation of abnormal noise due to the power plant bending is suppressed. Can be.

Further, the bolt insertion hole 1 formed in the fourth partition wall 12 and the rear end wall 6c of the lower block 6 is formed.
8 is the same as the length of the bolt insertion hole 18 formed in the other partition wall 11 and the like, the fourth partition wall 12 and the rear end wall 6c of the lower block 6 are formed.
, The support rigidity of the bearing cap 20 disposed at the bottom can be improved.

That is, when the lower portion of the bearing cap 20 is to be bolted without forming the concave portion 41, the bolt 19 having a large shaft length is reduced by the amount by which the rear end 6a of the lower block 6 bulges downward. Must be used. On the other hand, in the present embodiment, the formation of the recess 41 makes it possible to use the bolt 19 having a short shaft length, and shortening the bolt 19 increases the support rigidity of the bearing cap 20. can do.

[0037]

As is clear from the above description, according to the present invention, the rigidity of the rear end wall of the lower block is effectively increased by the closed cross-sectional structure formed by the pair of ribs and the like, and the reinforcing ribs and the like. Not only can the support rigidity of the bearing cap be further increased, but also the lengths of all bolts used for each bolt insertion hole in each partition wall and the rear end wall of the lower block are unified under short length dimensions. As a result, the respective support stiffnesses of the respective support portions of the bearing cap can be increased in a uniform state (equal support), and the bending force acting on the crankshaft can be effectively dealt with.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a lower half of an engine body.

FIG. 2 is a plan view of the lower block as viewed from above.

FIG. 3 is a sectional view taken along the line III-III shown in FIG. 2;

FIG. 4 is a sectional view taken along the line IV-IV shown in FIG. 2;

FIG. 5 is a bottom view of the lower block as viewed from below.

FIG. 6 is a side view of the lower block as viewed from the side.

FIG. 7 is a sectional view taken along the line VII-VII shown in FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine main body 2 Cylinder block main body 2a Cylinder bore 4 Crankshaft 5 Crank chamber 6 Lower block 6c Rear end wall of lower block 6e Side wall of lower block 6f Transmission mounting surface 6g Oil pan mounting seat part 7 Oil pan 9-12 Partition wall 18 Partition 18 Bolt insertion hole formed in the rear end wall of the wall and the lower block 19 Bolt 20 Bearing cap 40 Rib 41 Depression 42 Second rib (rib defining a depression)

Claims (1)

(57) [Claims] A crank chamber for accommodating a crankshaft is formed by a skirt portion of a cylinder block main body having a cylinder bore and a lower block fastened to a lower end of the skirt portion, and a rear end of the lower block is A rear end wall formed by a rear end wall of the lower block serving as a transmission mounting surface, wherein an oil pan is provided at a lower end of the lower block. The mounting seat is
It is formed slightly forward of the rear end of the lower block. The lower block extends between both side walls of the lower block and partitions the inner space of the lower block back and forth.
The partition wall is behind the rear end of the mounting seat of the oil pan.
Are also formed in the front-rear direction
Between the rear end wall of the lower block and the mounting seat of the oil pan.
The rear end of the lower block is spaced from the rear end by a certain distance.
Through a pair of ribs that bulge downwards toward the wall
The lower block is connected to the mounting pan of the oil pan.
The recess opens below the rear end of the
The lower block is formed on the outer side in the arrangement direction of the pair of ribs.
The rear end wall of the oil pan and the rear end of the oil pan mounting seat.
Reinforcing ribs are provided, of the plurality of partition walls, after the oil pan mounting seat.
After the partition wall behind the end and the mounting seat of the oil pan
At least one partition wall further forward than the end, and furthermore
Insert a bolt through the rear end wall of the lower block
Each of the holes is formed and inserted into each of the bolt insertion holes.
Bearings that support the crankshaft with bolts
The lower part of the cap is fixed to the lower block respectively
Is, the oil pan is behind the rear end of the mounting seat of the partition Kabe及
And the lower end opening of each bolt insertion hole in the rear end wall of the lower block
The position is located in the recess, and all bolt insertion holes
A block structure of an engine , wherein length dimensions of the engine are set to be the same .