JPS6337490Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in the coupling structure between a piston and a connecting rod in an internal combustion engine.

Conventionally, the piston and connecting rod of an internal combustion engine are connected by connecting the small end of the connecting rod to the piston in advance via a piston pin, and the large end of the connecting rod is formed into two halves, upper and lower, and connected to the crankshaft pin. The large end halves were set in such a way that they were sandwiched together, and the halves were connected via bolts.

Such a conventional structure has a large number of parts, requires a large number of assembly steps, and is not necessarily advantageous in terms of strength because the connecting rod and crankshaft are separated and combined, so the rigidity of the joints and connecting members is There is room for improvement, such as the need to increase strength.

The present invention has been made to improve the above-mentioned problems, and its purpose is to open the crankcase of an internal combustion engine at least in the axial direction of the crankshaft, including one surface of the end of the cylinder block on the bottom dead center side of the piston. The crankshaft is inserted into the crankcase through this opening, and the piston is installed into the inner diameter of the cylinder of the cylinder block. A hole is formed, and the piston pin is inserted into the piston with the small end of the conrod positioned approximately at the bottom dead center of the inner diameter of the cylinder with the hole of the large end fitted into the crank pin of the crankshaft. In the structure in which the pistons are connected through the cylinder block, a pin hole formed in the piston that is continuous with the opening and located approximately at the bottom dead center of the cylinder inner diameter can be exposed at the end of the cylinder block on the piston bottom dead center side. By forming a concave notch and inserting the piston pin from this concave notch into the pin hole of the piston and the hole in the small end of the connecting rod, it is possible to improve assembly efficiency, improve strength, and reduce the number of parts. The purpose of the present invention is to provide a coupling structure that reduces the number of connections.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows the first embodiment of the present invention, which is a cantilever crankshaft type, and the embodiment shows an overhead valve type, but it can also be used with a side valve type. Although the shaft is shown horizontally, it can also be used vertically.

In the internal combustion engine 1, the cylinder block part 3 and the crankcase part 4 are integrally cast as the main block part 2, and the cylinder head 5 is separately joined to the cylinder block part 3; however, the cylinder head 5 is integrally cast with the block part 3. It's okay. An opening 6 is formed parallel to the cylinder axis and in the axial direction of the crankshaft from the lower part 3a of the cylinder block part 3 to the same end of the bottom 4a of the crankcase part 4. Obstructed. If the cylinder head is integrally cast with the cylinder block and crankcase, the opening shall be provided obliquely to the cylinder axis and crankshaft axis so that the bottom reaches the outside of the cylinder inner diameter at the bottom of the crankcase. This makes it easy to process the cylinder and its ceiling, crankcase bearings, etc. from the inner diameter side.

Bearing portions 4c, 4 are located directly under the end wall 4b of the crankcase portion 4 and a portion of the inner diameter portion of the cylinder.
d, and on the other hand, a spark plug 8 is provided in the cylinder head 5.
and a valve 9 (only one shown in the figure) forming an intake and exhaust valve, one end of a valve rocker arm 10 provided on the cylinder head 5 and the end of the stem 9a are engaged, and the other end of the rocker arm 10 is engaged with the end of the stem 9a. The push rod 11 is engaged with one end of a push rod 11 extending in the cylinder axis direction, and the push rod 11 passes through passages 12a and 13a of housings 12 and 13 integrally provided on one side of the cylinder head and cylinder block portion 3, respectively, and the other end is Facing the part closer to one side of the crankcase part 4.

The crankshaft 15 is of a cantilever type having a shaft portion 15b only on one side of the web 15a.
The first journal portion 1 is connected to the first journal portion 1 through the bearing 16 at a portion outside of b and close to this and close to the extension of the cylinder inner diameter.
5c, a second journal part 15d near the outer end of the shaft part 15b is supported via a bearing 17, and a gear 15e is provided on the shaft part between the bearing parts, and the gears are provided so as to be perpendicular to each other. 18 gears 18
a, and the cam portion 18b was engaged with the lifter 11a at the end of the push rod 11 to form a valve mechanism.

In the above, a part of the lower part of the upper end of the opening 6 of the cylinder block part 3 has a recess 19 recessed upward in the cylinder axis direction that opens at the lower end 3b of the cylinder block part 3 so as to pass through the wall in the front-rear direction. establish. This is shown from the front in Figure 2. The piston 20 is inserted into the cylinder inner diameter part 3c in advance,
On the other hand, a pin portion 15f is formed in advance at an eccentric position on the end surface of the web of the crankshaft 15, and the hole portion 21b of the large end portion 21a of the connecting rod 21 is fitted into this pin portion 15f.
The axial direction is restricted by a stopper 22 and a bolt 24.
The large end 21a is not divided into upper and lower sections as in the conventional case, but is integrated into a single piece with a hole 21b formed therein. piston 20
A pin hole 20a is concentrically formed in the peripheral wall of the piston 20, and the piston 20 is set at the bottom dead center so that the small end 21c of the connecting rod 21 faces the inner diameter part.
d with the pin hole 20a, one of the pin holes 20a faces the recess 19, and the pin 23 is passed from the outside through one pin hole 20a, the small end hole 21d, and the other pin hole to connect the conrod. The small end and the piston are connected, and then the cover 7 is closed.

FIG. 3 shows an embodiment of a dual-supported crankshaft type internal combustion engine, in which the crankshaft 115 is formed of two axially divided members 115A and 115B,
15f, and the large end 121a of the connecting rod 121 is fitted into the pin portion 115f, and the aforementioned recess 119 is formed in the cylinder block portion 103, and the connecting rod is connected inside the piston 120 at the bottom dead center. The small end 121c was exposed, and a pin 123 was inserted from the outside through the recess 119 to connect the piston and the connecting rod small end. In this way, a dual-supported crankshaft type can also be implemented.

As is clear from the above, according to the present invention, the large and small ends of the connecting rod connecting the crankshaft and the piston can be assembled without breaking one of them, and in particular, the large end can be assembled without breaking unlike conventional methods, and the crankshaft pin The fitting of the large end to the piston, the fitting of the piston pin to the piston, and the small end of the connecting rod can be done at the bottom dead center of the piston.Therefore, there is no need for bolting, etc., reducing assembly man-hours. It is easy to assemble, and it is possible to improve ease of assembly and mass production.The number of parts can be reduced by eliminating the need for connecting members and half bodies, and in conjunction with the above, it is possible to reduce costs. It is advantageous in obtaining a simple and compact internal combustion engine, and it is possible to reduce the weight by reducing the number of parts, and it is extremely advantageous in terms of strength because the large end of the connecting rod can be integrated instead of being divided and joined. It is not necessary to form the end portions thickly as in the conventional case, and there are many advantages in this respect as well, such as weight reduction.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; Fig. 1 is a longitudinal sectional view of the first embodiment, Fig. 2 is a front view of the same essential parts, and Fig. 3 is a longitudinal sectional view of the second embodiment. be. In the drawings, 1 is the internal combustion engine, 3 is the cylinder block, 15 is the crankshaft, 19 is the recessed part, and 2
0 is a piston, 21 is a connecting rod, 21c is a large end, and 23 is a piston pin.

Claims (1)

[Scope of Claim for Utility Model Registration] An opening is formed in the crankcase of an internal combustion engine, including one surface of the end of the piston bottom dead center of the cylinder block, and is open at least in the axial direction of the crankshaft into which the crankshaft can be inserted. The crankshaft is assembled into the crankcase through this opening, and the piston is assembled into the inner diameter of the cylinder of the cylinder block, while holes are formed at both the large and small ends of the connecting rod, and the crank pin of the crankshaft is inserted into the crankshaft. The small end of the connecting rod is connected via a piston pin to the piston, which is positioned approximately at the bottom dead center of the inner diameter of the cylinder, with the hole of the large end fitted into the hole of the cylinder block. A concave notch is formed at the end of the piston on the bottom dead center side and is continuous with the opening and is capable of exposing a pin hole formed in the piston that is approximately located at the bottom dead center of the cylinder inner diameter. A connecting structure for a piston and connecting rod for an internal combustion engine, characterized in that the connecting rod is connected to the piston by inserting a piston pin into the pin hole of the piston and the hole at the small end of the connecting rod.