JP3591209B2 - Drill path structure - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a structure of drill paths which intersect each other and are formed between cylinder bores of a cylinder block of an internal combustion engine.
[0002]
[Prior art]
Drill paths 11 and 12 intersecting each other are formed between the cylinder bores of the cylinder block of the internal combustion engine, for example, as disclosed in Japanese Utility Model Laid-Open Publication No. 6-18640, and as shown in FIG. A part of the engine cooling water flowing from the inner water jacket to the cylinder head inner water jacket is passed to cool the portion between the cylinder bores.
The conventional drill paths 11 and 12 intersect each other substantially orthogonally and have the same diameter.
[0003]
[Problems to be solved by the invention]
However, the conventional drill path has the following problem.
(I) Since the drill paths are orthogonal to each other, the drill path is separated from the upper surface of the cylinder block except for the upper end thereof, and a portion close to the upper surface of the cylinder block between the cylinder bores of the cylinder block to be most cooled cannot be efficiently cooled.
(Ii) In order to cool a portion close to the upper surface of the cylinder block, it is only necessary to change the crossing angle of the drill path to bring the portion where the drill path is disposed closer to the upper surface of the cylinder block. In such a case, as shown in FIG. When machining the later drill path 12, the tip of the drill 14 may escape in the direction of the earlier drill path 11 at the intersection 13 at the intersection 13 and bend and break, thereby shortening the life of the drill.
(Iii) Further, since the drill paths having the same diameter intersect, the flow resistance and the pressure loss at the intersection increase, the cooling rate decreases, and the cooling efficiency between the bores deteriorates.
An object of the present invention is to improve cooling of a portion between cylinder bores of a cylinder block.
Another object of the present invention is to improve the cooling of the portion between the cylinder bores of the cylinder block and extend the life of the cutting tool (drill).
[0004]
[Means for Solving the Problems]
The present invention that achieves the above object is as follows.
(1) In a drill path structure having drill paths 1 and 2 intersecting in an X-shape between bores and having an angle of opening of the intersecting drill paths 1 and 2 toward the cylinder block upper surface of 90 ° or more, By making the diameters of the drill passes 1 and 2 different from each other and processing the larger diameter drill pass 1 after the smaller diameter drill pass 2, it is possible to suppress the escape of the drill bit when machining the larger diameter drill pass 1. Drill path structure characterized by the following.
( 2 ) The structure of the drill path according to (1), wherein the upper end of the larger diameter drill path 1 is arranged on the exhaust side.
[0005]
In the structure of the drill path in the above (1), the diameters of the intersecting drill paths are different from each other, so that the smaller diameter drill path is processed first, and then the larger diameter drill path is processed. The drill bit is supported by the surrounding cylinder block during machining of the larger drill path, and does not bend in the direction of the smaller diameter drill path when machining the larger diameter drill path. Thus, the intersection angle of the two drill paths can be freely selected, and the angle of the two drill paths that opens toward the upper surface of the cylinder block can be made larger than 90 ° so that the drill path can be closer to the upper surface of the cylinder block. Thus, the part to be cooled can be cooled more intensively. Further, by making the diameters of the two drill paths different, it is possible to reduce the pressure loss (combination pipe loss) at the intersection, as compared with the case of the same diameter, and to increase the cooling water flow velocity, The cooling efficiency in the region between the cylinder bores can be increased. Furthermore, by selectively arranging the upper end of the drill path having the larger diameter at the portion where the cooling is desired, the portion where the cooling is desired can be strongly cooled .
In the structure of the drill path above SL (2), by placing the larger upper end of the drill path of the diameter to the liquid zone paste side can be cooled strongly around the combustion chamber of the exhaust side, it is possible to suppress the knock it can.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 3 show the structure of a drill path according to an embodiment of the present invention.
1 and 2 show a cross section of a portion 5 between cylinder bores 3 of a cylinder block 4 of a multi-cylinder internal combustion engine. Drill paths 1 and 2 that intersect each other are formed in a portion 5 between the cylinder bores of the cylinder block 4. Drill paths 1 and 2 are cooling water passages formed by drilling, and guide a part of the cooling water passing through the water jacket 6 in the cylinder block 4 to the water jacket in the cylinder head 7.
[0007]
The angle θ of the intersecting drill paths 1 and 2 that opens toward the upper surface of the cylinder block is 90 ° or more. As a result, the two drill paths approach the upper surface of the cylinder block over the entire length of the drill path as compared with the case where they are orthogonal to each other, and cool the periphery of the combustion chamber to be strongly cooled.
The processing order of the drill paths 1 and 2 is as follows. First, the drill path 2 with the smaller diameter is drilled, and then the drill path 1 with the larger diameter is drilled.
[0008]
The diameters d ₁ and d ₂ of the _two drill passes 1 and ₂ are different from each other. Desirably, the ratio of the diameters of the drill passes 1 and 2 is about 1: 0.55. This ratio is a value that minimizes the joint pipe loss coefficient k.
Further, the larger diameter drill path 1 is arranged so that its upper end is located on the exhaust side, and the smaller diameter drill path 2 is arranged such that its upper end is located on the intake side.
[0009]
Next, the operation will be described.
Since the diameters of the two drill paths 1 and 2 are different from each other, the crossing angle of the drill paths 1 and 2 is not made to be a right angle by machining the larger diameter drill path 1 after the smaller diameter drill path 2. Can also be processed at a shallow angle (θ ≧ 90 °). That is, when machining the larger diameter drill path 1, at the intersection 8, the drill 9 is supported by the cylinder block at a portion 10 of the periphery of the cutting tool that does not intersect with the smaller diameter drill path 1, so that the drill path 2 is formed. The tip of the drill 9 does not bend toward the drill path 2 even when the drill 9 hits at a shallow angle. That is, even when θ is 90 ° or more, the drill path 1 can be processed without bending the drill tip, and the life of the drill can be extended.
[0010]
By machining the drill paths 1 and 2 at θ ≧ 90 ° as described above, the drill paths 1 and 2 can be made closer to the upper surface of the cylinder block, and the area around the combustion chamber at the position where the piston to be cooled has risen is strongly cooled. Will be able to do it. Thereby, efficient cooling between the cylinder bores can be performed.
[0011]
It is known that the joint pipe loss coefficient k is minimized when the diameter ratio of the drill path is set to about 1: 0.55. Therefore, when the pressure difference ΔP between the water jacket in the cylinder block and the water jacket in the cylinder head is constant, the flow velocity V becomes maximum when the joining pipe loss k is minimum, heat exchange is promoted, and cooling efficiency is improved. . This also improves the cooling between the cylinder bores.
Further, since the upper end side of the larger diameter drill path 1 is disposed on the exhaust side, the exhaust side of the periphery of the combustion chamber can be cooled more strongly than the intake side, and knocking can be suppressed.
[0012]
【The invention's effect】
According to the structure of the drill path of the first aspect, since the diameters of the two drill paths are different from each other, the crossing angle of the drill path can be made shallow (θ ≧ 90 °), whereby the upper portion between the cylinder bores is strongly cooled. And the life of the drill can be extended .
According to the structure of the drill path of 請 Motomeko 2, except that the same as the effect of the first aspect is obtained, it can be cooled strongly equi zone paste side, there is an effect that it is possible to suppress the occurrence of knocking.
[Brief description of the drawings]
FIG. 1 is a schematic plan view of a multi-cylinder internal combustion engine.
FIG. 2 is a sectional view of a portion between cylinder bores including a structure of a drill path according to one embodiment of the present invention, and is a sectional view taken along line 2-2 of FIG. 1;
FIG. 3 is a cross-sectional view showing a state in which a drill bit is supported at an intersection of a drill path.
FIG. 4 is a cross-sectional view of a portion between cylinder bores including the structure of a conventional drill path.
FIG. 5 is a cross-sectional view showing a state in which the drill is bent at the time of drill pass processing in FIG. 4;
[Explanation of symbols]
1 Drill path (larger diameter drill path)
2 drill path (the smaller diameter path)
5 Cylinder bore section 8 Drill path intersection 9 Drill

Claims (2)

In a drill path structure having drill paths 1 and 2 intersecting in an X-shape between bores and having an angle of opening of the intersecting drill paths 1 and 2 toward the cylinder block upper surface of 90 ° or more, the intersecting drill path 1 2, the diameter of the drill path 2 is made different from each other, and the larger diameter drill path 1 is processed after the smaller diameter drill path 2 so that the escape of the drill bit at the time of processing the larger diameter drill path 1 can be suppressed. Drill path structure characterized by: The drill path structure according to claim 1, wherein the upper end of the larger diameter drill path (1) is arranged on the exhaust side.

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