JP3699309B2 - Siamese type cylinder block structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the structure of a so-called siamese type cylinder block in which a portion between adjacent cylinder bores is formed in a common cylinder wall among cylinder blocks in a multi-cylinder internal combustion engine.
[0002]
[Prior art]
In general, in this siamese type cylinder block, the internal combustion engine can be reduced in size and weight as much as the space between the cylinder bores can be reduced. However, on the other hand, the cooling performance of the common cylinder wall portion between the cylinder bores is improved. Will be reduced.
[0003]
Therefore, conventionally, the common cylinder wall portion is provided with cooling water passage holes that are inclined diagonally downward to communicate between the cooling water jackets formed on the left and right outer sides of the cylinder bore rows. In this way, the cooling performance of the common cylinder wall is ensured (for example, see Japanese Utility Model Laid-Open Nos. 59-127852 and 7-224716).
[0004]
In this case, the cooling water passage hole for the common cylinder wall portion is a drill for drilling the cooling water passage hole. One of the cooling water jackets is open to the upper surface of the cylinder block. It is drilled by inclining and entering obliquely downward while rotating from the portion to be rotated.
[0005]
[Problems to be solved by the invention]
However, a portion between the cylinder bores outside the cooling water jackets is integrally provided with a boss portion for screwing a head bolt for fastening the cylinder head to the cylinder block. It is necessary for a drill to be drilled with an inclined hole to enter the boss so as to avoid it without contacting the boss. Therefore, since the length of the cooling water passage hole becomes longer, not only the time required to incline and drill the cooling water passage hole becomes longer, but the cooling water passage hole becomes longer. There was a problem that the drill frequently broke during drilling of the water passage hole.
[0006]
When the bosses for the head bolts on both sides are disposed at the positions shifted outward, the internal combustion engine is increased in size accordingly.
[0007]
An object of the present invention is to solve this problem without causing an increase in the size of an internal combustion engine.
[0008]
[Means for Solving the Problems]
In order to achieve this technical problem, the present invention
“A portion of the cylinder block between the cylinder bores is configured as a common cylinder wall, and an opening hole for the cooling water jacket is formed on both the left and right sides of the common cylinder wall on the upper surface of the cylinder block. Further, a head bolt boss portion is disposed on the outer side, and a cooling water passage hole that communicates between the left and right cooling water jackets is formed in the common cylinder wall from one of the opening holes. In the one that is drilled obliquely downward,
In the head bolt boss portion, a portion adjacent to the opening hole is provided with a notch portion in which only a corner portion with respect to the upper surface of the cylinder head is cut out . "
It was configured as follows.
[0009]
[Operation and effect of the invention]
Thus, by providing a notch in the portion adjacent to the opening hole in the boss portion for the head bolt, when the cooling water passage hole is inclined and drilled by the drill, this drill is the boss for the head bolt. Since it can be avoided at the notch, the angle of entry of the drill with respect to the upper surface of the cylinder block can be reduced, and as a result, inclined to the common cylinder wall. The length of the cooling water passage hole to be drilled can be shortened without shifting the head bolt boss portion outward.
[0010]
Further, by providing a notch portion in the head bolt boss portion adjacent to the opening hole, an area where the head bolt boss portion contacts the cooling water in the cooling water jacket is defined as the notch portion. Can be increased.
[0011]
Therefore, according to the present invention, it is possible to shorten the time required for drilling the cooling water passage hole in the common cylinder wall portion without increasing the size of the internal combustion engine, and to reduce the breakage of the drill. In addition, the cooling performance by the cooling water jacket can be improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
[0013]
In this figure, reference numeral 1 denotes a siamese type cylinder block in which a portion between adjacent cylinder bores 2 is formed as a common cylinder wall 3.
[0014]
Inside the cylinder block 1, cooling water jackets 4 a and 4 b are formed on the left and right sides of each cylinder bore 2, and on the left and right sides of the common cylinder wall 3 on the upper surface 1 a of the cylinder block 1. Opening holes 5a and 5b of the cooling water jackets 4a and 4b are opened, and a cylinder head (not shown) with respect to the cylinder block 1 is provided at a portion outside the both opening holes 5a and 5b. Boss portions 8a and 8b having female screw holes 7 into which head bolts 6 for fastening are screwed are provided.
[0015]
Then, a cooling water passage hole 9a communicating between the left and right cooling water jackets 4a, 4b is connected to the common cylinder wall 3 by using a drill A having a small diameter d, and one of the two opening holes 5a, 5b. When drilling in a slanting downward direction from the opening hole 5a, a drill having a diameter D is formed in a portion adjacent to the one opening hole 5a in one boss portion 8a located outside the one opening hole 5a. By cutting out the notch 10a by counterboring using B or an end mill, a portion of the one boss 8a adjacent to the one opening hole 5a is connected to the cylinder head 1 of the portion. A notch 10a is formed so as to cut out only a corner with respect to the upper surface 1a.
[0016]
In the drawing, a cooling water passage hole 9b that crosses the cooling water passage hole 9a in an X-shape is used as a drill A having a small diameter d, and the other opening hole 5b of the two opening holes 5a and 5b. In this case, the portion of the other boss portion 8b located outside the other opening hole 5b is also adjacent to the other opening hole 5b. Similarly, by notching a notch portion 10b by counterboring using a drill B or an end mill having a diameter D, the portion adjacent to the other opening hole 5b in the other boss portion 8b Of these, it is necessary to provide a notch 10b that cuts only the corner of the cylinder head 1 with respect to the upper surface 1a .
[0017]
By the way, when the cooling water passage holes 9a and 9b are drilled in the common cylinder wall 3 so as to be inclined obliquely downward from both the opening holes 5a and 5b using the drill A having a small diameter d, as shown in FIG. Further, when the boss portions 8a, 8b outside the opening holes 5a, 5b are not provided with the notches 10a, 10b, the drill A for drilling the cooling water passage holes 9a, 9b has the boss portion 8a, In order not to come into contact with 8b, the approach angle θ with respect to the upper surface 1a of the cylinder block 1 in the drill A must be increased, and therefore the length of the cooling water passage holes 9a and 9b becomes longer. is there.
[0018]
On the other hand, as described above, when the notches 10a and 10b are provided in the boss portions 8a and 8b adjacent to the opening holes 5a and 5b, the cooling water passage holes 9a and 9b are formed in the drill A. Since the drill A can be prevented from coming into contact with the boss portions 8a and 8b at the notch portions 10a and 10b when drilling at a slant, the cylinder block in the drill A correspondingly. 1 can be reduced, and as a result, the lengths of the cooling water passage holes 9a and 9b that are inclined and drilled in the common cylinder wall 3 can be shortened. By providing the portions 10a and 10b, the area where the boss portions 8a and 8b come into contact with the cooling water in the cooling water jackets 4a and 4b can be increased.
[Brief description of the drawings]
FIG. 1 is an enlarged plan view of a main part showing an embodiment of the present invention.
2 is a cross-sectional view taken along the line II-II of FIG.
FIG. 3 is a sectional view showing a state before reaching the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder bore 3 Common cylinder walls 4a and 4b Cooling water jackets 5a and 5b Cooling water jacket opening holes 8a and 8b Head bolt bosses 9a and 9b Cooling water through holes 10a and 10b Notches

Claims (1)

A portion between the cylinder bores of the cylinder block is configured as a common cylinder wall, and an opening hole of the cooling water jacket is further provided on both the left and right sides of the common cylinder wall on the upper surface of the cylinder block. A head bolt boss portion is provided on the outer side, and a cooling water passage hole communicating with the left and right cooling water jackets on the common cylinder wall is slanted from one of the opening holes. In the one that is drilled in the downward direction,
A siamese type cylinder block characterized in that a notch portion is formed in a portion adjacent to the inside of the opening hole in the boss portion for the head bolt so as to cut out only a corner portion of the portion with respect to the upper surface of the cylinder head. Structure.

Images