JP4457239B2 - Cylinder head cooling structure machining method - Google Patents

Description

  The present invention relates to a method for processing a cooling structure in the vicinity of an intake / exhaust hole of a cylinder head of an internal combustion engine.

With the aim of improving transportation efficiency, while the engine output of automobiles is increasing, it is a challenge how to effectively cool the cylinder head in order to keep the engine operating at a high load.

An intake / exhaust port is formed in the cylinder head adjacent to the combustion chamber of the cylinder, and the exhaust port is always exposed to high heat during engine operation.
On the other hand, the intake port draws fresh air into the cylinder, and the fresh air wants to warm around the intake port considering the charging efficiency (the ratio of oxygen per unit volume of the sucked fresh air is proportional to the charging efficiency) Absent.
However, the intake port is adjacent to the exhaust port, and fresh air (intake) supplied into the cylinder is increased by the heat in the vicinity of the exhaust port. Therefore, a water jacket having a water passage (water gallery) through which engine cooling water flows is formed in the cylinder head, and cooling in the water jacket (water gallery) of the water jacket is particularly focused on the vicinity of the exhaust port. ing.

  FIG. 6 is a diagram in which the cylinder head 110 having four valves per cylinder is turned over, and the intake port 101 and the exhaust port 102 are viewed from the combustion chamber side of a cylinder (not shown). FIG. 7 is a sectional view taken along the line XX in FIG. 6, and the lower side of FIG. 7 represents the combustion chamber side.

  In FIG. 7, a cooling water channel (water gallery) 105 is formed in a region between the exhaust port 102 and the exhaust port 102. Here, when the thicknesses T1 and T2 in the direction from the inner wall surface of the water channel 105 toward the center line of the port are compared with the thickness T3 from the inner wall of the water channel C to the end surface 110e of the cylinder head 110, it is clear that T3 is T1. , T2 is formed thicker.

When this ratio of thickness is large, a heat accumulation (overheated part) is partially made, which is not preferable in terms of valve opening / closing motion. Alternatively, thermal stress is generated, which is not preferable in terms of strength.

In order to correct such a problem, as shown in FIGS. 8 and 9, the region between the ports 102 and 102 of the cylinder head 110 is cut with a processing tool having a spherical tip (for example, a drill 103 or an end mill). A reduction in the thickness of the region is performed. (See Patent Document 1)
FIG. 9 shows a state in which a drill 103 having a spherical tip is fed by cutting in the thickness direction (arrow Y direction) without moving the drill shaft.
FIG. 8 is a perspective view three-dimensionally showing a state in which cutting has been completed by the method of FIG.
In FIG. 8, reference numerals 122 and 112 indicate processing marks formed in the region between the ports.

When the non-uniform thickness of the cylinder head 110 is made close to the uniform thickness by such a method, the protrusion E is formed at the boundary portion with the port at the cut portion. Since the protrusion E is still an overheated point and sharply pointed, the stress is concentrated and adversely affects the strength.
Microfilm of No. Sho 63-4766

  The present invention has been proposed in view of the above-described problems of the prior art. In the cylinder head of an engine, there is provided a machining method for a cooling structure of a cylinder head that can eliminate overheating and effectively exhibit cooling by cooling water. The purpose is to provide.

  According to the present invention, partial arcs (R1) are formed in the respective regions between the exhaust ports (2, 2) and between the intake and exhaust ports (1, 2) of the cylinder head (10) of the internal combustion engine having four valves per cylinder. And a cooling structure of a cylinder head (10) for forming a concavely curved cutting surface (22, 12) on the combustion chamber side, and perpendicular to the cylinder head (10) surface to be processed Using an end mill (3) that rotates around an axis and has a cylindrical tip corner portion subjected to R processing, respectively, along virtual lines (L, L1) connecting the centers of two ports (2, 2, and 1, 2). Then, the end mill (3) is sent to process the cutting surfaces (22, 2), and the sharpened portions of the cutting surfaces (22, 12) in the imaginary line (L, L1) direction are sharpened (4 ) R processing unit ( 2) processed, processing the different R processing unit (R3) a pointed portion of the imaginary line (L, L1) and the end face of the right angle of the cutting face (22, 12) with a grinder.

The cooling structure for a cylinder head according to the present invention having such a configuration is a port whose cutting direction is adjacent to the combustion chamber side in the region between any of the intake and exhaust ports (1, 2) of the cylinder head (10) of the internal combustion engine. And the cut surfaces (12, 22) after cutting are concavely curved with respect to the combustion chamber side so as to include the partial arc (R1), and the intake and exhaust ports (1, 1, 2) By reducing the thickness between any of the ports, the thickness of the cylinder head (10) is made uniform, heat is dispersed, and the cooling effect by the cooling water is improved.

In the cutting surface (12, 22), chamfering or rounding (R2, R3) is formed at the ridge line portion between the region between any of the intake / exhaust ports (1, 2) before cutting and the cutting surface after cutting. As a result, there are no protrusions after cutting, and therefore no stress concentration points.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, a first embodiment will be described with reference to FIGS.

FIG. 1 is a view of the intake port 1 and the exhaust port 2 viewed from the combustion chamber side of a cylinder (not shown) with the cylinder head 10 having four valves per cylinder turned over according to the first embodiment. FIG. 2 corresponds to the cross-sectional view taken along the line XX in FIG. 1 (upside down from FIG. 1), and is immediately before performing a thinning (cutting) process for improving cooling. It is the figure which showed the state prepared in the start position. FIG. 3 is a view showing a cross-sectional view taken along the line XX of FIG.

In FIG. 1, there is a thinning (cutting) mark 22 in a region between the two exhaust ports 2 and 2 on the end surface of the cylinder head 10 on the combustion chamber side. Further, in the region between the exhaust port 2 and the intake port 1 (two locations) on the end surface of the cylinder head 10 on the combustion chamber side, there is a thinning (cutting) mark 12.

4 is a partially enlarged view taken along the line YY in FIG. 1, and FIG. 5 is an enlarged view of a part A in FIG. 3 (XX sectional view in FIG. 1) (upside down from FIG. 3). Is).

As shown in FIGS. 2 and 4, the processing tool 3 is, for example, an end mill in which a cylindrical tip corner portion is R-processed (chamfered).
In FIG. 1, the machining direction (feed) of a machining tool (for example, an end mill) is reciprocating or unidirectional along the direction of arrow B, that is, along a virtual line L connecting the centers of two exhaust ports 2 and 2.

If the corner portion at the front end is cut with a processing tool (for example, an end mill) subjected to R processing, the processing trace on the end face of the cylinder head 10 is in a sharp state (in FIG. 4, R2 is formed by R processing). In this state, the sharp point is likely to become a heat pool. For example, after machining with an end mill, the sharp point is, for example, R1 cut with the end mill by a small grinder 4. By applying a convex R process (R2) to the opposite side, the heat accumulation location can be removed.

In the cross section shown in FIG. 5 (enlarged view of FIG. 3 and the XX cross section of FIG. 1), the interphase line formed by the exhaust port 2 and the cutting trace 22 (the boundary line between the cutting trace and the inner peripheral surface of the exhaust port) Since the sharp point, in fact, 2 is R-processed and R3 is formed in FIG. 5, the sharp point is not shown), so that the R-process (R3) is performed with, for example, a small grinder as described above. It is desirable to apply. FIG. 5 shows a state where the R processing (R3) is performed.

It should be noted that the illustrated embodiment is merely an example, and is not a description of the purpose of limiting the technical scope of the present invention.

The perspective view explaining the thinning (cutting) process of the cylinder head which concerns on 1st Embodiment of this invention. The figure which responded to the XX cross-sectional arrow view of FIG. 1, and was the state just before performing the thinning process for cooling improvement, and showed the state which prepared the processing tool in the process start position. The XX cross-section arrow figure of FIG. 1 is a partially enlarged view taken along the line Y-Y in FIG. The A section enlarged view of FIG. 3 (XX sectional drawing of FIG. 1). The perspective view which looked at the cylinder head in a prior art from the combustion chamber side. XX sectional view of FIG. The perspective view which showed the state which performed the thinning (cutting) process for cooling improvement in the prior art. XX sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Intake port 2 ... Exhaust port 3 ... Processing tool 4 ... Grinder 5 ... Cooling water channel (water gallery)
10 ... Cylinder head 12, 22 ... Processing trace (cut surface)

Claims (1)

A partial arc (R1) is included in each region between the exhaust ports (2, 2) and between the intake and exhaust ports (1, 2) of the cylinder head (10) of the internal combustion engine having four valves per cylinder, and the combustion chamber In the processing method of the cooling structure of the cylinder head (10) for forming the cutting surfaces (22, 12) curved concavely on the side, the cylinder rotates around an axis perpendicular to the cylinder head (10) surface to be processed. End mill (3) having a rounded tip corner is used, and the end mill (3) is taken along imaginary lines (L, L1) connecting the centers of two ports (2, 2, and 1, 2), respectively. To cut the cutting surfaces (22, 12), and the sharpened portions of the cutting surfaces (22, 12) in the direction of the imaginary lines (L, L1) are sharpened with an R processing section ( R2) Cylinder head cooling structure characterized in that another R processing section (R3) is machined by a grinder at a pointed end of the cutting surface (22, 12) perpendicular to the virtual line (L, L1). Processing method.

Images