JPH0111953Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a main body of a multi-cylinder engine in which a cylinder head and a cylinder block in which a plurality of cylinder bores are arranged are fastened together by tightening bolts via a gasket. Regarding structure.

(Prior Art) Generally, for example, a four-cylinder automobile engine as described in the automobile structural manual "Bongo Bondi Structure and Maintenance (Toyo Kogyo Co., Ltd.)"
As illustrated in FIG. 1, a cylinder head 2 is attached to the upper surface of a cylinder block 1 having a plurality of cylinder bores via a gasket 3 with a tightening bolt 4.
(10 pieces), a head cover 5 is attached to the upper part of the cylinder head 2, and a transmission case 6 is attached to one end of the cylinder block 1 to form the main body structure. In this case, each of the tightening bolts is arranged between the cylinder bores in the cylinder bore arrangement direction and at both ends in the cylinder bore arrangement direction, that is, in the cylinder bore arrangement direction.

In such a multi-cylinder engine, it has been widely known that the cylinder block 1 is thermally deformed due to combustion heat, and various countermeasures have been proposed.

(Problem to be solved by the invention) However, in such a cylinder block 1, in addition to thermal deformation, when the cylinder head 2 is tightened using all the tightening bolts 4, the entire cylinder block is tightened. There is a problem that deformation occurs.

In FIGS. 2 and 3, the tightening deformation of the cylinder block 1 is shown in an exaggerated manner. In other words, in the vertical plane, the central part of the cylinder block 1 in the direction in which the cylinder bores 7 are arranged is curved downward, as shown by the chain line in FIG. It rises at both ends in the direction, and is warped into a curved shape as a whole, and partially deforms into a wave shape in each cylinder bore 7. Furthermore, in the horizontal plane, as shown in FIG. 3, each cylinder bore 7 is crushed in the cylinder bore arrangement direction by the warpage of the cylinder block 1 and deformed into an elliptical shape. Such deformation tends to be particularly noticeable when the cylinder block 1 is made of aluminum alloy.

One of the reasons why such tightening deformation occurs in the cylinder block 1 is that the area on which the tightening force of each tightening bolt 4 acts is different, and the surface pressure on the mating surface 1a with the cylinder head 2 is uneven. In other words, at both ends in the cylinder bore arrangement direction, the contact pressure of the mating surface 1a with the cylinder head 2 is lower than that at the center, so that a bending moment corresponding to the degree of compression of the gasket 3 acts. Then, when such tightening deformation occurs in the cylinder block 1,
The parallelism of the mating surfaces of the cylinder block 1 and the cylinder head 2 is lost, gas leakage occurs due to poor sealing, and the roundness of the cylinder bore 7 is lost, causing uneven wear. Gas leakage is particularly noticeable in high compression type engines such as diesel engines, resulting in problems such as reduced fuel efficiency.

The object of the present invention is to provide a means that can suppress the deformation of the entire cylinder block itself that occurs when the cylinder block and cylinder head are tightened using all the tightening bolts as described above. .

Incidentally, as a means to improve the adverse effects caused by the tightening deformation mentioned above, a dummy head having a shape and rigidity similar to the cylinder head was tightened to the cylinder block, and the inner peripheral surface of the cylinder bore was machined while the cylinder block was being tightened and deformed. However, it is necessary to tighten and attach a dummy head to each cylinder block using a large number of fastening bolts (10 for a 4-cylinder cylinder) before machining, which poses the problem of reducing productivity. .

(Means for Solving the Problems) In order to solve such problems, the present invention solves the above-mentioned tightening deformation because the tightening bolts are arranged in the cylinder bore arrangement direction. In particular, in view of the problem caused by insufficient surface pressure at the outer portions of the tightening bolts at both ends in the cylinder bore arrangement direction, the tightening bolts at both ends are attached to at least one of the mating surfaces of the cylinder head and cylinder block. By providing a protrusion so that the outer part of the position protrudes more than the central part in the cylinder bore arrangement direction, the surface pressure at the outer part of the tightening bolt position is increased,
This suppresses deformation of the entire cylinder block itself.

That is, in the present invention, a cylinder head and a cylinder block in which a plurality of cylinder bores are disposed are connected to each other through a gasket by tightening bolts located between the cylinder bores in the cylinder bore arrangement direction and at both ends in the cylinder bore arrangement direction. In a multi-cylinder engine that is fastened by The present invention is characterized in that a protruding portion is provided so that the surface thereof protrudes beyond the mating surface of the central portion in the cylinder bore arrangement direction.

(Function) In the main body structure of the multi-cylinder engine described above, when the cylinder head and cylinder block are fastened together with all the tightening bolts via the gasket, the protrusions will cause the cylinder bores to tighten at both ends in the cylinder bore arrangement direction, especially at this end. The surface pressure at the outer portions of the tightening bolt positions at both ends in the cylinder bore arrangement direction is higher than when there is no protrusion. This suppresses the generation of a bending moment that would cause the aforementioned tightening deformation of the entire cylinder block.

(Effect of the invention) Therefore, according to the invention, the mating surfaces at both ends in the cylinder bore arrangement direction and at least at the outer part of the tightening bolt positions at both ends in the cylinder bore arrangement direction are located at the center in the cylinder bore arrangement direction. Since the protrusion is provided so as to protrude beyond the mating surface of the cylinder head and cylinder block, the generation of bending moments that would cause tightening deformation of the entire cylinder block is suppressed, and when the cylinder head and cylinder block are fastened together, the mating surface of the two is A parallel body structure can be easily obtained.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

<Example 1> As shown in FIG. 4, in the cylinder block 10 of this example, the mating surface 10a at the upper end is formed into a curved surface, and the cylinder bores 7, 7 at both ends in the cylinder bore arrangement direction are tightened outwardly. The protrusions 11, 11 are provided so that the mating surfaces at the outer portions than the bolt positions 10b are higher by a predetermined amount than the mating surfaces at the central portions in the cylinder bore arrangement direction. The rest of the structure is the same as the conventional cylinder block 1 shown in FIG.

<Example 2> As shown in FIG. 5, the mating surface 12a at the upper end of the cylinder block 12 of this example has an outer tightening bolt position 12b of the cylinder bores 7, 7 at both ends in the cylinder bore arrangement direction. A protruding portion 1 that is higher than the center portion in the cylinder bore arrangement direction
3 and 13 are formed.

As in both of the above embodiments, the cylinder block 1 has protrusions 11 and 13 formed such that both ends in the cylinder bore arrangement direction protrude by a predetermined amount from the center.
0 and 12 as shown in FIG.
When all the tightening bolts 4 are tightened through the gasket 3, the surface pressure at both ends increases corresponding to the protrusions 11 and 13, and the tightening deformation of the entire cylinder block as shown in FIG. 2 occurs. The generation of bending moment is suppressed, and the mating surface 10a of the cylinder head 2 and the mating surface 10a of the cylinder blocks 10, 12,
12a, the seatability is improved and the roundness of the cylinder bore 7 is ensured.

Note that the amount of protrusion of the protrusions 11 and 13 is the amount of curvature due to tightening deformation (difference in height between the center and both ends).
is 0.1~0.2mm, whereas 0.2~0.2mm is 0.1~0.2mm.
It is preferable to set it to 0.5 mm.

Further, in the above embodiment, the cylinder block 10,
Projections 11 and 13 are provided on the mating surfaces 10a and 12a of 12.
is formed on the cylinder head 2 side, or may be formed on both sides.

[Brief explanation of the drawing]

1 to 3 are explanatory diagrams showing deformed states of the cylinder block, FIG. 4 is a front view of the cylinder block showing one embodiment of the present invention, and FIG. 5 is a cylinder showing another embodiment of the present invention. FIG. 3 is a front view of the block. 2...Cylinder head, 3...Gasket, 4
...Tightening bolt, 7...Cylinder bore, 10,1
2...Cylinder block, 10a, 12a...Mating surface, 10b, 12b...Tightening bolt position, 1
1, 13... protrusion.

Claims (1)

[Scope of utility model registration request] A multi-cylinder cylinder in which a cylinder head and a cylinder block in which a plurality of cylinder bores are arranged are fastened via a gasket by tightening bolts located between the cylinder bores in the cylinder bore arrangement direction and at both ends in the cylinder bore arrangement direction. In the engine, at least one of a mating surface of the cylinder head and a mating surface of the cylinder block has a mating surface at both ends in the cylinder bore arrangement direction and at least at a portion outward from the tightening bolt position at both ends. A main body structure of a multi-cylinder engine, characterized in that a protruding part is provided so as to protrude beyond a mating surface of a central part in the direction.