JPH10184443A - Timing chin case mounting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent oil leakage due to breakage and plastic deformation at a corresponding part to a boundary between the cylinder block of a timing chain case and a cylinder head. SOLUTION: In a boil hoe 10 for a molding bolt to fix the peripheral edge of a timing chain case 3, a pitch distance L at a boundary part between a cylinder block 1 and a cylinder head 2 is made to a value larger than a pitch distance l of other part and by increasing a span at the boundary part, the generation of a high stress due to a thermal expansion difference between the cylinder block 1 and the cylinder head 2 is suppressed. Further, a seal bearing reduced due to the increase of the length of one span is ensured by forming a different bolt hole 12 in an inside position situated at a proper distance from a peripheral edge part. An excessive stress is prevented from generation at the boundary part as a necessary seal bearing is ensured and leakage of oil due to breakage and plastic deformation is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure for a timing chain case, and more particularly to a mounting structure for a timing chain case which is mounted across one end surface of a cylinder block and one end surface of a cylinder head.

[0002]

2. Description of the Related Art Conventionally, many timing chain cases are mounted on the lower surface of a portion of a cylinder head protruding from one end of a cylinder block and on one end surface of the cylinder block. It is common that one end face and one end face of a cylinder head are made the same face and a timing chain case is attached over both of them.

[0003] Referring to FIG. 3, in FIG. 3 (a), reference numeral 1 denotes a cylinder block, 2 denotes a cylinder head, and a straddle extends over both one end of the cylinder block 1 and one end of the cylinder head 2. Thus, the timing chain case 3 is provided, and the peripheral edge thereof is fastened and fixed by the mounting bolts 4. Reference numeral 5 denotes an oil pan provided below the cylinder block 1, and reference numeral 6 denotes a cylinder head cover provided above the cylinder head 2.

As shown in FIG. 3 (b), a peripheral wall 3b is formed on a peripheral edge of the timing chain case 3 and is continuous with a ceiling wall 3a. And a FIPG on its joint end face 3d.
Seal groove 7 in which a liquid filling gasket 8 called
Are formed. 3 (a) and 3 (c)
As shown in FIG. 5, a bolt hole 10 through which the mounting bolt 4 is inserted is formed in a boss 9 protruding from the peripheral wall 3b so as to protrude beyond the seal flange 3c. The mounting bolts 4 are arranged at substantially equal intervals l both in a portion corresponding to the cylinder block 1 and the cylinder head 2 and in a portion straddling both of them.

[0005]

In some cases, the cylinder block 1 is made of cast iron and the cylinder head 2 is made of an aluminum alloy. In this case, the thermal expansion coefficients of the cylinder block 1 and the cylinder head 2 are reduced. Due to the difference, when the engine is hot, as shown in FIG.
One end of the cylinder head 2 protrudes from one end of the cylinder block 1, and conversely, at a low temperature of the engine, one end of the cylinder block 1 protrudes from one end of the cylinder head 2 as shown in FIG. The amount of protrusion is 0.2-0.
As a result, an excessive stress is generated in a portion H of the timing chain case 3 facing the boundary between the cylinder block 1 and the cylinder head 2, and the H portion of the timing chain case 3 is damaged or plastically deformed. In some cases, there is a problem that a gap is generated and oil leaks out.

[0006] Even when both the cylinder block 1 and the cylinder head 2 are made of an aluminum alloy or cast iron, the same problem occurs because the temperature change of the cylinder head 2 is larger than that of the cylinder block 1.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, the present invention prevents the occurrence of excessive stress in a portion corresponding to the boundary between a cylinder block and a cylinder head of a timing chain case, and prevents the portion from being damaged or plastically deformed. It is an object of the present invention to provide a timing chain case mounting structure that prevents oil leakage.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a mounting structure of a timing chain case which is mounted on both ends of a cylinder block and one end of a cylinder head with mounting bolts. The bolt holes for mounting bolts are arranged at an appropriate pitch on the periphery of the cylinder, and the pitch interval of the bolt holes is made larger at the boundary between the cylinder block and the cylinder head than at other parts, so that the timing chain case The relatively high rigidity of the peripheral part causes a large stress to be generated due to displacement.However, by increasing the span, reduce the stress, and from the peripheral part of the timing chain case at the boundary between the cylinder block and the cylinder head. Longer span by arranging another bolt hole inside the appropriate distance Therefore, it is possible to secure the reduced sealing surface pressure, thereby preventing the occurrence of excessive stress in the portion corresponding to the boundary between the cylinder block and the cylinder head of the timing chain case while securing the necessary sealing surface pressure. To prevent oil leakage due to breakage and plastic deformation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The overall arrangement of the engine is the same as that of the conventional example described with reference to FIG.
The description will be referred to and the same components will be denoted by the same reference numerals in the following description.

In FIG. 1, a timing chain cover 3 is provided so as to straddle both one end of a cylinder block 1 and one end of a cylinder head 2. As shown in FIGS. 1 and 2A, a peripheral wall 3b continuous with the ceiling wall 3a is formed at the peripheral edge of the timing chain case 3, and a thick seal flange 3c protrudes from the outer periphery of the distal end thereof. Has been established. Joining end face 3 of seal flange 3c to one end face of cylinder block 1 and one end face of cylinder head 2
A seal groove 7 for disposing a liquid sealing gasket 8 (see FIG. 3B) is formed in d.

As shown in FIGS. 1 and 2 (b),
A boss 9 protrudes from the peripheral wall 3b beyond the seal flange 3c, and a bolt hole 10 through which the mounting bolt 4 (see FIG. 3C) is inserted is drilled. This boss 9
And the arrangement interval of the bolt holes 10 is the arrangement interval L at a portion straddling both the cylinder block 1 and the cylinder head 2.
Is set to l <L with respect to the arrangement interval l in other parts.

Further, as shown in FIGS. 1 and 2 (c),
Appropriate distance D from peripheral wall 3b of timing chain case 3
Only at the inner position and in the vicinity of the boundary between the cylinder block 1 and the cylinder head 2, a bolt seat 11a for a mounting bolt is formed on the outer surface of the ceiling wall 3a, and the boss portion 11 reaching one end surface of the cylinder block 1 from the inner surface is formed. Another bolt hole 12 is provided which is protruded and through which the mounting bolt 4 is inserted. Then, the timing chain case 3 is fixed by the mounting bolts 4 inserted through the bolts 10 and 12.
Are mounted over one end surface of the cylinder block 1 and one end surface of the cylinder head 2.

Further, at the T-shaped boundary where one end face of the cylinder block 1 and the cylinder head 2 intersects with the joining end face 3d of the timing chain case 3, as shown in FIG. End face 3d
A very shallow, substantially arc-shaped concave groove 13 is formed to prevent concentration of stress on the timing chain case 3 due to the corners of the cylinder block 1 and the cylinder head 2 during relative expansion and contraction.

The depth δ of the groove 13 is 0.2 corresponding to the relative expansion and contraction difference between the cylinder block 1 and the cylinder head 2.
It is set to about 0.3 mm.

According to the above configuration, the peripheral portion of the timing chain case 3 is laid over both the one end surface of the cylinder block 1 and the one end surface of the cylinder head 2 by the mounting bolts 4 arranged at an appropriate pitch. When the cylinder block 1 and the cylinder head 2 have a difference in thermal expansion and contraction when the engine is cold and hot, the peripheral portion of the timing chain case 3 has relatively high rigidity due to the peripheral wall 3b and the seal flange 3c. As a result, a large stress is generated due to the displacement due to the difference in thermal expansion and contraction between the cylinder block 1 and the cylinder head 2.
The pitch L between the mounting bolts 4 is larger than the pitch l between the other parts at the boundary between the cylinder head 2 and the cylinder head 2, so that the span between the fixing positions by the mounting bolts 4 becomes longer and the stress is reduced. Can be. Further, since the concave grooves 13 are formed, stress concentration due to corners can be eliminated. On the other hand, it is conceivable that the sealing surface pressure decreases as the span becomes longer. However, since the inner position at an appropriate distance from the peripheral portion is fixed by the mounting bolt 4 inserted into another bolt hole 12, the sealing surface pressure is reduced. Can also be secured. As a result, the cylinder block 1 of the timing chain case 3 is secured while securing the necessary sealing surface pressure.
Excessive stress is prevented from being generated at a portion corresponding to the boundary between the cylinder head 2 and the cylinder head 2, and oil leakage due to breakage or plastic deformation of the portion can be prevented.

[0016]

According to the present invention, as described above, bolt holes for mounting bolts are provided at appropriate pitch intervals on the peripheral edge of the timing chain case, and the bolt holes are provided at the boundary between the cylinder block and the cylinder head. The spacing between the fixing points of the mounting bolts is longer because the pitch interval of the cylinder is larger than the other parts, reducing the stress generated at the peripheral edge of the timing chain case due to the difference in expansion and contraction between the cylinder block and the cylinder head. And another bolt hole is located at an appropriate distance from the periphery of the timing chain case at the boundary between the cylinder block and the cylinder head, so that the sealing surface pressure that decreases as the span becomes longer is secured. Can be
Therefore, while maintaining the necessary sealing surface pressure, excessive stress is prevented from being generated at the part corresponding to the boundary between the cylinder block and cylinder head of the timing chain case, and oil leakage due to breakage and plastic deformation of that part is prevented. can do.

[Brief description of the drawings]

1A and 1B show an embodiment of a mounting structure of a timing chain case of the present invention, wherein FIG. 1A is a front view, FIG. 1B is a side view, and FIG.

FIGS. 2A and 2B are partial cross-sectional views of FIG. 1, wherein FIG. 2A is a cross-sectional view taken along the line AA, FIG. 2B is a cross-sectional view taken along the line BB, and FIG. .

3A and 3B show a mounting structure of a conventional timing chain case, wherein FIG. 3A is an overall side view, and FIG. 3B is FF of FIG.
FIG. 3C is a cross-sectional view taken along a line GG in FIG.

FIG. 4 is an explanatory view of a state at a high temperature and a low temperature in the mounting structure of the timing chain case of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder head 3 Timing chain case 4 Mounting bolt 10 Bolt hole 12 Another bolt hole

Claims (1)

[Claims] 1. A timing chain case mounting structure which is mounted with mounting bolts across both one end surface of a cylinder block and one end surface of a cylinder head. In addition to providing bolt holes for mounting bolts, make the pitch interval between the bolt holes larger at the boundary between the cylinder block and the cylinder head than at other parts, and at the timing chain case at the boundary between the cylinder block and the cylinder head. A timing chain case mounting structure, wherein another bolt hole is disposed at a position inside a proper distance from a peripheral portion.