JPH10288080A - Structure of drill path - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the cooling of a part between cylinder bores of a cylinder block by forming each diameter of drill paths, which cross each other between the bores, different from each other. SOLUTION: Drill paths 1, 2, which are formed in a part 5 between cylinder bores 3 of a cylinder block 4 and which cross each other, are provided so as to lead a part of the cooling water, which passes a water jacket 6 inside of the cylinder block 4, to a water jacket inside of a cylinder head. Angle θ formed by these crossing drill paths 1, 2 and opened to a top surface of the cylinder block 4 is set at 90 degree or more so as to strongly cool the periphery of a combustion engine. Diameter ratio of diameters d1 , d2 of the two drill paths 1, 2 is desirably set at about 1:0.55, and the drill path 1 having a larger diameter d1 is worked after working the drill path 2 having a smaller diameter d2 so as to prolong the lifetime of a drill.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of drill paths intersecting each other formed between cylinder bores of a cylinder block of an internal combustion engine.

[0002]

2. Description of the Related Art Drill paths 11 and 12 which intersect each other are formed between cylinder bores of a cylinder block of an internal combustion engine, for example, as disclosed in Japanese Utility Model Laid-Open Publication No. 6-18640 and as shown in FIG. A portion of the engine cooling water flowing from the water jacket in the cylinder block to the water jacket in the cylinder head passes therethrough to cool the portion between the cylinder bores. The conventional drill paths 11 and 12 cross each other substantially orthogonally and have the same diameter.

[0003]

However, the conventional drill path has the following problems. 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 it is impossible to efficiently cool a portion between the cylinder bores of the cylinder block desired to be cooled most near the upper surface of the cylinder block. In order to cool the portion close to the upper surface of the cylinder block, it is only necessary to change the crossing angle of the drill path so that the portion where the drill path is provided is closer to the upper surface of the cylinder block. In such a case, as shown in FIG. When machining the drill path 12, the tip of the drill 14 at the intersection 13 may escape in the machining direction of the earlier drill path 11 and bend and break, thereby shortening the life of the drill. In addition, 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]

The present invention to achieve the above object is as follows. (1) A drill path structure characterized in that the diameters of the drill paths intersecting between the bores are different from each other. (2) The structure of the drill path according to (1), wherein the angle of the intersecting drill path opening toward the cylinder block upper surface is 90 ° or more. (3) The structure of the drill path according to (1), wherein the diameter of the intersecting drill path is about 1: 0.55. (4) The structure of the drill path according to (1), wherein the upper end of the larger diameter drill path is located on the exhaust side.

In the structure of the drill path of the above (1), since the diameters of the intersecting drill paths are different from each other, 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 diameter drill path, and does not escape in the direction of the smaller diameter drill path when machining the larger diameter drill path. Thus, the intersection angle of the two drill passes can be freely selected, and the angle of the two drill passes that opens toward the upper surface of the cylinder block is 90 °.
°, the drill path can be made closer to the upper surface of the cylinder block, and the portion to be cooled can be cooled more intensively. Also, 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 it is possible to increase the cooling water flow velocity, The cooling efficiency at the portion between the cylinder bores can be increased. Further, 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 of the above (2), two drill paths can be brought closer to the upper surface of the cylinder block. In the structure of the drill path of the above (3), since the merge pipe loss can be reduced as compared with the cross structure of the drill path having the same diameter, the flow rate of the cooling water can be increased, and the cooling efficiency is increased. In the structure of the drill path of the above (4), by arranging the upper end of the larger diameter drill path on the exhaust side, the area around the combustion chamber on the exhaust side can be cooled strongly, and knocking can be suppressed.

[0006]

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, 2 that intersect with each other
Are formed. Drill paths 1 and 2 are cooling water passages formed by drilling. A part of the cooling water passing through the water jacket 6 in the cylinder block 4 is supplied to the cylinder head 7.
Guide to the inner water jacket.

The angle θ of the intersecting drill paths 1 and 2 opening toward the upper surface of the cylinder block is set to 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 smaller diameter drill path 2 is drilled, and then the larger diameter drill path 1 is drilled.

The diameters d ₁ and d ₂ of the _two drill paths 1 and ₂ are different from each other. Preferably, drill path 1,
The ratio of the diameters of 2 is about 1: 0.55. This ratio is a value that minimizes the joint pipe loss coefficient k. Also, the larger diameter drill path 1 is arranged so that the upper end thereof is located on the exhaust side, and the smaller diameter drill path 2 is disposed.
It is arranged so that its upper end is located on the intake side.

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. At a shallow angle (θ ≧ 90 °). That is, when machining the larger diameter drill path 1, the drill 9 is supported by the cylinder block at the intersection 8 at the portion 10 of the periphery of the cutting tool that does not intersect with the smaller diameter drill path 1, thereby forming the drill path 2. 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, θ is 9
Even when the angle is 0 ° or more, the drill path 1 can be processed without bending the drill tip, and the life of the drill can be extended.

By machining the drill paths 1 and 2 at θ ≧ 90 ° as described above, the drill paths 1 and 2 can be brought 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 is raised is raised. It becomes possible to cool strongly. Thereby, efficient cooling between cylinder bores can be performed.

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 junction 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]

According to the structure of the drill path according to the first aspect,
Since the diameters of the two drill paths are different from each other, the crossing angle of the drill paths can be made shallow (θ ≧ 90 °),
As a result, the upper part between the cylinder bores can be cooled strongly, and the life of the drill can be extended. According to the structure of the drill path of the second aspect, by setting θ ≧ 90 °, the upper portion between the cylinder bores can be selectively and strongly cooled. According to the structure of the drill path according to the third aspect, since the diameter ratio of the drill path is set to about 1: 0.55, the loss between the junctions can be minimized, and the flow velocity can be increased to increase the cooling efficiency between the cylinder bores. it can. According to the structure of the drill path of the fourth aspect, in addition to the same effect as the first aspect, there is an effect that the exhaust side can be strongly cooled and occurrence of knocking can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a multi-cylinder internal combustion engine.

2 is a cross-sectional view of a portion between cylinder bores including a structure of a drill path according to an embodiment of the present invention, and is a cross-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 a crossing point 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 where the drill is bent at the time of drill pass processing in FIG. 4;

[Explanation of symbols]

 Reference Signs List 1 Drill path (larger diameter drill path) 2 Drill path (smaller diameter drill path) 5 Section between cylinder bores 8 Drill path intersection 9 Drill

Claims (4)

[Claims] 1. A structure of a drill path, wherein the diameters of the drill paths intersecting between the bores are different from each other. 2. The structure of a drill path according to claim 1, wherein the angle of the intersecting drill path opening toward the upper surface of the cylinder block is 90 ° or more. 3. The diameter of the intersecting drill path is about 1: 0.5.
The structure of the drill path according to claim 1, wherein 4. The drill path structure according to claim 1, wherein the upper end of the larger diameter drill path is located on the exhaust side.