JPS6325324Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a motorcycle engine.

BACKGROUND ART In an air-cooled multi-cylinder engine, particularly in an air-cooled multi-cylinder engine for a motorcycle, a passage 2 through which cooling air passes is formed between cylinders 1 arranged in parallel, as shown in FIG. 1, in order to increase cooling efficiency. In general, an engine has cylinder blocks 4 to 6 (here, reference numeral 4) mounted on the crankcase 3, as shown in FIG.
6 to 6 indicate each part of one cylinder block, and the same applies to the following description. ) and cylinder head 7, insert the tightening bolt 8 into the through holes 4a to 7a drilled in these, and screw the threaded part 8a of this bolt 8 into the screw hole 3a of the crankcase 3. Then, a nut 10 is screwed onto the threaded portion 8b via the packing 9, and the nut 10 connects the cylinder blocks 4 to 6 and the cylinder head 7.
is tightened and fixed to the crankcase 3.

In an engine with such a configuration, the tightening bolt 8
The stem portion 8c of the cylinder block 4 is directly exposed to the outside air, and muddy water and the like are exposed to the through hole 4a of the cylinder block 4 and the tightening bolt 8.
Foreign matter 11 such as earth and sand tends to accumulate in the gap between the water and the water, and as the water evaporates, foreign matter 11 such as earth and sand accumulates. Therefore, when the cylinder blocks 4 to 6 are removed from the crankcase 3 as shown in FIG. 3 during engine disassembly, the foreign matter 11 falls out and is removed from the crankcase 3.
There was a fear that I would become depressed.

In addition, if the engine is exposed to water while driving and the cylinder blocks 4 to 6, cylinder head 7, tightening bolt 8, etc. are temporarily cooled and the temperature drops, the cylinder blocks 4 to 6, cylinder head 7, etc.
etc., the original temperature returns immediately, but the temperature of the tightening bolt 8 returns to a steady state later than that of the cylinder blocks 4 to 6 and the cylinder head 7. Therefore, the axial stress of the tightening bolt 8 changes temporarily due to the difference in thermal expansion between the cylinder blocks 4 to 6, the cylinder head 7, and the tightening bolt 8, and the tightening of the threaded portions 8a, 8b or the nut 10 is caused. This can easily lead to a decrease in power.

The present invention has been made in view of the above-mentioned points, and includes a collar which is formed by winding a thin plate member into a substantially cylindrical shape and whose diameter can be expanded elastically, and which is fitted into a through hole of a cylinder head and a cylinder block. A motorcycle in which a tightening bolt is inserted into the through hole and the gap between the through hole and the tightening bolt is closed with a collar to prevent foreign matter such as earth and sand from entering the through hole and the crankcase. It provides engines.

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 4 shows a longitudinal section of a collar, which is a main component of an embodiment of the present invention. The collar 12 is made of a thin plate-like member having elasticity and heat resistance, such as a thin rigid plate, wound into a substantially cylindrical shape. It is formed by turning, and both sides 12a and 12b are formed so as to slightly overlap as shown in FIG. When a pressing force is applied to the outer periphery of this rolled plate-shaped collar 12, the outer diameter is deformed to become smaller, and when the pressing force is released, the collar 12 returns to its original outer diameter due to elastic force. That is,
The collar 12 is designed to be elastically expandable. The outer diameter D of this collar 12 in a steady state is the through hole 4 of the cylinder blocks 4 to 6 (Fig. 6).
The dimensions are set to be slightly larger than the hole diameter d of holes a', 5a, and 6a, and the length L is at least from the step 4d of the cylinder blocks 4 to 6 forming the cooling air passage 2 (Fig. 1) to the upper surface. 6d (FIG. 6).

As shown in FIG. 6, cylinder blocks 4 to 6 placed directly above the crankcase 3 are provided with through holes 4a', 5a, and 6a, and the cylinder head 7 is provided with through holes. 7a is drilled (see Figure 2). The through holes 4a' are formed concentrically with a stepped portion 4d, and the diameter of the upper hole 4b is set to be the same as the diameter of the through holes 5a, 6a, and 7a. Further, the hole diameter of the lower hole 4c is smaller than the hole diameter of the hole 4b, and the difference is approximately the same as the wall thickness of the collar 12.

When assembling the cylinder, first, as shown in FIG.
Insert in order. In this case, an external force is applied to the collar 12 so as to wrap it around the collar 12 to reduce its outer diameter, and the collar 12 with the reduced diameter is inserted into the through hole 6.
The insertion work becomes easy by inserting it into the holes a, 5a and the hole 4b. The step portion 4d is provided in the through hole 4a'.
are formed, and the upper hole 4b is the through hole 5a,
It has the same dimensions as 6a. Therefore, color 1
The collar 12 is inserted until the end of the collar 12 comes close to the stepped portion 4d. After this insertion, when the external force on the collar 12 is released, the collar 12 elastically expands in diameter, and its outer peripheral surface 12c comes into pressure contact with the inner peripheral surfaces of the through holes 6a, 5a and hole 4b. That is, the collar 12 is fitted into the through holes 6a, 5a and the hole 4b. Further, the length L of the collar 12 is shorter than the dimension l, and when the collar 12 is inserted as described above and the end surface on one side is close to the stepped portion 4d of the through hole 4a', the end surface on the other side is is the same as the upper surface 6b of the cylinder blocks 4 to 6, or is slightly inserted into the through hole 6a. In this way, the through holes 6a, 5a of the cylinder blocks 4 to 6, which are located apart from each other via the cooling air passage 2, are
The holes 4b of the through holes 4a' are connected by a collar 12.

After inserting the collar 12 into the through holes 6a and 5a of the cylinder blocks 4 to 6 and the hole 4b of the through hole 4a' in this way, the stem of the center part is inserted into the collar 12 in comparison with the thread diameter of the end part. Tightening bolt with small diameter 8
(indicated by a dashed line), and screw the threaded portion 8a into the threaded hole 3a of the crankcase 3. Also, a cylinder head 7 (first
(Fig.) is mounted, and as described above, the cylinder blocks 4 to 6 and the cylinder head 7 are tightened and fixed to the crankcase 3 (indicated by the dashed line) using the nuts 10.

In such a configuration, the upper surface 4e of the collar 12 or cylinder block 4, which is partially exposed to the outside air.
Even if muddy water etc. adheres to the outer peripheral surface 1 of the collar 12,
2c is in pressure contact with the inner circumferential surface of each of the through holes 6a, 5a, 4a', thereby preventing muddy water from entering into the hole 4b of the through hole 4a'. Moreover, since the collar 12 is thin, the stepped portion of the collar 12 (the gap created by overlapping both sides 12a and 12b)
The intrusion of muddy water into the hole 4b is extremely small and can be almost ignored, and the intrusion of earth and sand etc. into the hole 4b can be prevented.

When removing the cylinder blocks 4-6 from the crankcase 3, even if the cylinder blocks 4-6 are lifted, the collar 12 remains inserted into the hole 4b and is removed together with the cylinder blocks 4-6.
Foreign matter such as earth and sand does not fall into the crankcase 3.

Furthermore, even if the cylinder 1, collar 12, etc. are splashed with water and temporarily cooled, the outer diameter of the collar 12 can be changed freely, so the cylinder blocks 4 to
Since the outer diameter of the collar 12 changes depending on the diameter of the hole 4b and the through holes 5a and 6a of No. 6, overstress may occur between the collar 12 and the hole 4b and the through holes 5a and 6a, or gaps may occur. This does not occur, and the dustproofing effect remains unchanged. Furthermore, the tightening bolt 8 is protected by the collar 12, and its temperature changes are extremely small and can be almost ignored.Therefore, loosening of the threaded portion or nut due to thermal expansion as described above will not occur. do not have.

As explained above, according to the present invention, the collar fitted into the through holes of the cylinder head and cylinder block elastically expands in diameter and comes into pressure contact with the inner peripheral surface of the through holes. The gap between the bolt and the tightening bolt is closed by the collar, which prevents foreign matter such as earth and sand from entering the through hole, and also prevents these foreign matter from entering the crankcase when the engine is disassembled. In addition, since the tightening bolt is inserted into the collar and protected by the collar, even if the collar or cylinder block is temporarily cooled by water, the temperature change of the tightening bolt can be prevented. is extremely small, and it is possible to prevent a decrease in the tightening force of the threaded portion of the tightening bolt or the nut due to the difference in thermal expansion with the cylinder block.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the cooling air passage of an air-cooled multi-cylinder engine, Fig. 2 is an explanatory sectional view of the main parts of a conventional air-cooled multi-cylinder engine, and Fig. 3 is an explanatory diagram when the engine shown in Fig. 2 is disassembled. , FIG. 4 is a longitudinal sectional view showing the main parts of an embodiment of the present invention, FIG. 5 is an end view of FIG. 4, and FIG. 6 is a main part of the engine of a motorcycle according to an embodiment of the present invention. FIG. 1...Cylinder, 2...Cooling air passage, 3...Crankcase, 4-6...Cylinder block, 7
...Cylinder head, 8...Tightening bolt, 10...
...Natsuto, 12...color.

Claims (1)

[Scope of utility model registration request] In a motorcycle engine in which a tightening bolt is inserted into a through hole drilled in a cylinder head and a cylinder block, and the cylinder head and cylinder block are assembled to a crankcase using the tightening bolt, the thin plate member is formed into a substantially cylindrical body. inserting a resiliently expandable collar wound into a shape into the through hole, and inserting the tightening bolt into the collar;
A motorcycle engine characterized in that a gap between the tightening bolt and the through hole is closed by the collar.