JPH0122929Y2 - - Google Patents

Description

[Detailed explanation of the idea] Technical field The present invention relates to an engine crankcase.

BACKGROUND ART In a crankcase, a cover is provided on a crankshaft end bearing portion in order to prevent lubricating oil from leaking from the bearing portion.

Conventionally, this cover has been attached with bolts or the like while maintaining oil-tightness through a sheet gasket such as an asbestos beater sheet. When trying to obtain oil tightness using such a sheet gasket, since the contact area between the cover and the crankcase body and the gasket is large, it is necessary to reduce the pressure of the cover to the crankcase body and gasket relatively. It has to be bigger. Therefore, the number of bolts for attaching the cover is relatively large, which is a factor in increasing the weight of the engine.

In addition, many crankcases are split along a plane that includes the rotational axis of the crankshaft, but in such split-type crankcases, the split parts tend to become misaligned when the engine is assembled, and the above-mentioned cover It was difficult to maintain the flatness of the mounting surface.

On the other hand, since the gasket mentioned above is made of a relatively hard material and thin, it takes considerable time to deform the gasket to compensate for the low flatness of the cover mounting surface and obtain the desired oil tightness. It requires a high degree of skill, requires a large number of man-hours, and is expensive.

Summary of the invention Therefore, an object of the present invention is to provide a crankcase that enables reduction in engine weight and cost, and also achieves improved oil tightness.

The crankcase according to the present invention has a cover that covers an end bearing of a crankshaft to prevent oil leakage, and has an end facing the side of the bearing and the cover, respectively. Two cylindrical protrusions are formed concentrically, and a housing groove is formed at at least one end of the inner two cylindrical protrusions, and the cover is inserted into the housing groove. The cover is characterized in that an annular elastic member that is oil-tight on the inside and outside is accommodated therein, and that the cover is fixed to the bearing part by a plurality of fixing members provided on the outer cylindrical convex part.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The illustrated engine is a double overhead camshaft four-cylinder engine used in motorcycles.

As shown in the figure, the crankcase 1 is divided into two parts: an upper crankcase 2 and a lower crankcase 3. crank case 1
A cylinder 4, a cylinder head 5, and a cylinder head cover 6 are each fixedly attached to the upper part of the cylinder with stud bolts (not shown) or the like. Four pistons 7 are inserted into the cylinder 4,
The crankshaft 1 is connected to the crankshaft 1 via a connecting rod 8 and a connecting rod bearing 9, respectively.
Connected to 0.

The crankshaft 10 is supported by an upper crankcase 2 and a lower crankcase 3 via a crankshaft bearing 11.

The bearing portion 13 of the crankcase 1 that supports the left end portion 12 of the crankshaft 10 is provided with substantially cylindrical convex portions 14 and 15 having a double structure, and the end surfaces of the cylindrical convex portions 14 and 15 are smooth. Processed. The bearing portion 13 has cylindrical convex portions 14 and 15.
A substantially bowl-shaped cover 18 having double cylindrical convex portions 16 and 17 corresponding to the above and having smoothed end surfaces is preferably attached by three fixing members, that is, hexagon socket head bolts 19, Bearing part 13
Together, they form a space 20.

A housing groove, that is, an annular groove 21 is provided on the end surface of the cylindrical convex portion 16, and an O-ring 22 made of a viscoelastic member is fitted into the annular groove 21.
Since the depth of the annular groove 21 is smaller than the cross-sectional outline of the O-ring 22, the O-ring 22 is compressed and tightly fitted between the annular groove 21 and the end face of the cylindrical convex portion 14, and is inserted into the inside and outside of the cover 18. This provides oil-tightness.

In addition, the O-ring 22 is attached to the protrusion 1 instead of the protrusion 17.
Since the O-ring 22 is provided in the annular groove 21 of the bolt 19, the O-ring 22 can be made small.
It is now possible to equalize the adhesion of the

The bearing part 13 has a space 2 where lubricating oil flows.
A communication hole 23 that communicates the inside of the crankcase 1 with the space 20 and is parallel to the rotation axis of the crankshaft 10 is provided for the purpose of preventing a rise in pressure within the crankcase 1 .

On the other hand, the bearing portion 25 of the crankcase 1 that supports the right end portion 24 of the crankshaft 10 is provided with substantially cylindrical convex portions 26 and 27 having a double structure. A substantially bowl-shaped cover 28 is attached to the cylindrical convex portion 27 by a plurality of hexagon socket head bolts 29 to the bearing portion 25.
It is attached to cover the bearing part 25, and forms a space part 30 together with the bearing part 25. The cylindrical convex portion 26 is provided with an oil seal 31 that fits into the right end portion 24 to maintain oil tightness between the inside of the crankcase 1 and the space 30.

Further, the crankshaft 10 is provided with a lubricating oil supply hole 32 for supplying lubricating oil to the sliding surfaces of the connecting rod bearing 9 and the crankshaft bearing 11 with respect to the crankshaft 10.

Furthermore, as shown in FIG.
A may be provided.

Further, in the illustrated engine, as usual, the exhaust side camshaft 34 that drives the exhaust valve 33 is connected to the crankshaft 10 by a cam chain 35, and the intake valve (see the figure) is connected in parallel to the exhaust side camshaft 34. An intake side camshaft (not shown) is provided to drive the camshaft (not shown).

Further, inside the lower crankcase 3, a hydraulic multi-disc clutch 36, a transmission 37, and an output shaft 38 are mounted on various bearings 39 such as ball bearings.
It is rotatably supported by.

Effects of the Invention As detailed above, in the crankcase according to the present invention, the cover that covers the end bearing of the crankshaft is attached via an annular viscoelastic member that has a small contact area with the cover and the crankcase. Therefore, the pressure required to press the cover onto the crankcase is small. Therefore, the number of cover mounting bolts can be reduced, and since there are fewer bolt mounting holes, the strength of the crankcase bearing part is increased accordingly, and the wall thickness of the crankcase near the bearing part can be made thinner, reducing the overall weight of the engine. It also contributes to

In addition, by reducing the number of cover mounting bolts, the strength of the entire bearing is increased, and
This increases the degree of freedom in selecting the installation position of the communication hole shown in .

Furthermore, in the crankcase according to the present invention, even if the flatness of the mounting surface of the cover is slightly distorted due to misalignment between the divided parts of the crankcase during engine assembly, the annular viscoelastic member The cover elastically deforms according to the rotation, ensuring oil tightness inside and outside the cover.

Therefore, the work that requires skill to improve the flatness is unnecessary, and the number of man-hours and costs can be reduced.

Furthermore, in the crankcase according to the present invention, two parts are provided on the side part of the bearing part that pivotally supports the end part of the crankshaft and the cover placed over the bearing part, so that the respective ends thereof face each other. Two cylindrical protrusions are formed concentrically, and an accommodation groove is formed at at least one end of the two inner cylindrical protrusions, and the accommodation groove is provided with an inner and outer part of the cover. An annular elastic member is housed therein to maintain oil-tightness of the cover, and the cover is fixed to the bearing portion by a plurality of fixing members provided on the outer cylindrical convex portion.

In this way, the inner and outer double-structured cylindrical protrusions are provided, the annular elastic member is interposed between the inner cylindrical protrusions, and the fastening force is applied to the outer cylindrical protrusion by the fixing member. Due to this additional structure, the surface pressure is constant over the entire circumference of the annular elastic member, and high oil tightness is ensured. Moreover, because of this double structure, the shape of the end of the inner cylindrical convex portion separated from the fixing member can be made to be close to a perfect circle without considering the shape of the fixing member and its placement position. As a result, the overall shape of the annular elastic member can be made into a perfect circle or a very simple shape close to this, and the surface pressure on the entire pressure-receiving surface of the annular elastic member can be made uniform. In other words, it contributes to improving oil tightness.

[Brief explanation of the drawing]

Figure 1 is a partial sectional view of the engine according to the present invention.
FIGS. 2 and 3 are cross-sectional views showing a part of the engine. Explanation of symbols of main parts 1...Crankcase, 2...Atsupa crankcase, 3...Lower crankcase, 4...Cylinder, 5...Cylinder head, 6...Cylinder head cover, 7...Piston, 8 ... Connecting rod, 10 ... Crankshaft, 11
... Crankshaft bearing, 13 ... Bearing portion, 14, 15, 16, 17 ... Cylindrical convex portion, 1
8...Cover, 19...Hexagon socket head bolt, 20
... Space, 21 ... Annular groove, 22 ... O-ring, 23 ... Communication hole, 33 ... Exhaust valve, 34
...Exhaust side camshaft, 35...Cam chain,
36...Hydraulic multi-disc clutch, 37...Transmission, 38...Output shaft.

Claims (1)

[Scope of utility model registration request] A crankcase having a cover that covers an end bearing part of a crankshaft to prevent oil leakage, the side part of the bearing part and the cover each having two cylindrical protrusions with their ends facing each other. The inner two portions of the cylindrical convex portion are formed concentrically.
An accommodating groove is formed in at least one end of the two cylindrical protrusions, and an annular elastic member that makes the inside and outside of the cover oil-tight is accommodated in the accommodating groove. A crankcase characterized in that the crankcase is fixed to the bearing portion by a plurality of fixing members provided.