JPS5843642Y2 - Die-cast cylinder block for horizontally opposed air-cooled engines - Google Patents

Description

[Detailed description of the invention] This invention relates to improving the cylinder block of a horizontally opposed air-cooled engine, and allows the cylinder and crankcase to be die-cast integrally without waste, thereby reducing manufacturing costs. To facilitate assembly of various parts within a crankcase without making the case too dog-shaped.

Examples of this invention will be described below with reference to the drawings.

FIG. 1 is a vertical cross-sectional rear view of an overhead valve type horizontally opposed forced air-cooled engine, and FIG. 2 is a schematic cross-sectional plan view of the engine.

In the figure, the engine includes a cylinder block 1, a head block 2, an outer shell structure such as a gear cover 3 and a head cover 4 that are covered on the rear surface of the cylinder block 1, and a crankshaft 5 and a camshaft 6 housed therein. , piston 1,
It is composed of interlocking members such as a connecting rod 8 and a valve train 9.

The above cylinder block 1 is made of aluminum alloy and includes a crankcase 10 and left and right side walls 10 of the crankcase 10.
The cylinder 11 protruding from L and 10R is integrally formed by a guicast casting method.

The crankcase 10 is formed into a box shape as a whole by left and right side walls 10L, IOR, front and rear side walls 10F, 10B, and an upper wall 10U, and the entire bottom thereof is open as a joint surface for the oil pan P.

Each of the above-mentioned side walls 10L, IOR, 10F, and IOB is formed so as to slope outward toward the bottom.

This angle of inclination is set to be more uniform than the usual die-cutting slope.

On the outer surface of the front wall 10F of the crankcase 10, as shown in FIGS.
A boss 13 for mounting is provided protrudingly provided, and a boss 14 for a bearing is provided protrudingly provided on its inner surface.

A bearing boss 15 for the crankshaft 5 is formed on the rear wall 10B of the case 10, and a peripheral wall 16 for joining the gear cover 3 is protruded from the periphery of the bearing boss 15.

The crankshaft 5 is supported by both the front and rear bearing bosses 14 and 15 via bearings, and the camshaft 6 is disposed below the crankshaft 5 and is supported by the bearing boss 14 and a bearing boss formed on the gear cover 3. be done.

The cylinder 11 has a litchi sleeve 17 made of cast iron inside.
is cast and fixed, and a large number of cooling fins 18 are formed protrudingly in a circumferential manner on the outer surface of the cooling fin.

The inner end of the cylinder 11 is provided so as to protrude inward from the left and right side walls 10L and 10R of the crankcase 10.

The upper portions of both side walls 10L and 10R continuous to the cylinder 11 are formed along the inner wall of the cylinder 11, as shown by dotted lines in FIGS. 4 and 5.

Reference numeral 19 denotes a tappet supporting boss formed continuously on the lower surface of the inner wall of the cylinder 11.

The cylinder block 1 constructed as described above is molded using the following five molds.

That is, the horizontal plane passing through the center of the left and right cylinders 11 is defined as the mold dividing plane C1, and the first mold that forms the external shape of the cylinder block 1 above this, the dividing plane C1, and the centers of both cylinders 11 are A second mold forms the outer shape of the cylinder block 1 in front of the vertical plane C2, and a second mold forms the rear part of the lower half of the cylinder block 1 facing the second mold. 3, a fourth mold that forms the internal shape of the crankcase 10, and a fifth mold that forms the external shape between the lower rear half of the right cylinder 11 and the peripheral wall 16 of the timing gear chamber. It is a type.

The first mold is above, the second and third molds are in front and behind, and the fourth mold is
, the fifth mold is cut downward.

The internal shape of the timing gear chamber and the boss 13 and recess on the front wall 10F of the crankcase 10 shown in FIG.
and a second mold.

1 and 2, 20 is a combustion pump, 21 is a recoil starter, 22 is a carburetor, 23 is a cooling fan,
24 is a governor unit.

Since the present invention is configured as described above, it has the following effects.

B. Dividing die casting molds tends to be complicated, and the entire inner circumferential surface of the crankcase is formed in a shape that gradually increases in size as it goes downward. It can be formed with a mold and easily cut out of the mold, making it possible to easily, efficiently and accurately die-cast cylinder blocks for horizontally opposed air-cooled engines.

The base end of the cylinder, the tappet boss, and the bearing boss that protrude into the inner surface of the crankcase are located closer to the open bottom surface, which is the die opening, so the smaller they are, the closer they are to the back when viewed from the die opening. There is no need to add extra material for cutting out the mold, and this makes it possible to reduce the weight of the entire crankcase.

Moreover, material costs can be reduced by the weight reduction.

...Since the crankcase is formed in a flat wave shape, the entire engine width, that is, the width between the horizontally opposing cylinder tips and the dirt space, can be made smaller, and the bottom of the crankcase can be made smaller. By increasing the opening area of the crankcase, you can easily and efficiently insert your hand into the crankcase to assemble parts, such as attaching a connecting rod to the crankshaft, with a sufficiently large operating space.

Second, since the bottom area of the crankcase can be made sufficiently large in relation to the overall width of the engine, the stability of the entire engine when installed can be greatly improved.

Incidentally, as shown in the embodiment, the crankcase 10L.

By forming the upper half of the intersection of the cylinder 10R and the cylinder 11 along the inner end of the cylinder 11, the entire circumference of the connection between the cylinder 11 and the left and right side walls 11L and 11R is made more narrow, making it easier to hold the cylinder 11. Not only can it be made with high strength and high rigidity, but it can also eliminate waste.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional rear view of a horizontally opposed forced air-cooled engine according to this invention, Fig. 2 is a cross-sectional plan view of the same engine, and Figs. 3, 4, and 5 are longitudinal cross-sections showing only the cylinder block. They are a rear view, a central vertical side view, and a cross-sectional plan view. 5... Crankshaft, 6... Camshaft, 10-... Crankcase, IOF, 10B, 10L, IOR, 10U
...10 walls, 11... cylinders, 14.15...
・Boss for bearing, 19...Boss for tappet.

Claims (1)

[Scope of claim for utility model registration]
It is integrally formed into a box shape with an open bottom surrounded by 10B, 10L, IOR, and IOU, and the left and right side walls 10L and 10R of this are formed integrally.
The left and right cylinders 11 are integrally extended outward from the upper part, and the base end of each cylinder 10 is connected to the left and right side walls 10L, I.
The tappet boss 19 is inserted into the inner surface of the OR, and the tappet boss 19 is integrally inserted into the inner surface of the left and right side walls 10L below the base end of the cylinder 100, and the tappet boss 19 is integrally inserted into the inner surface of the IOH, and A bearing boss 1 that supports a crankshaft 5 and a camshaft 6 disposed below the same shaft 5 on the inner surfaces of 10F and 10B.
4 and 15, and the cylinder 1'I, tappet boss 19, and bearing boss 14, 15 are connected to each circumferential side wall 10F, IO
In each of B, IOL, and IOR, a cylinder 11 with a large external shape and a bearing boss 14 for the crankshaft 5 are placed on the upper side.
15 are arranged, and these upper projections are provided so as to protrude into the inner surface of the crankcase 10 than the lower projections, and each peripheral side wall 10F, IOB, IOL. 10R is a die-cast cylinder block for a horizontally opposed air-cooled engine that has a tapered bottom with a slope greater than the slope used for punching.