JPH086606B2 - Structure of inline engine - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the structure of an in-line engine.

[0002]

2. Description of the Related Art As a conventional in-line engine structure, for example, there is one shown in FIG. That is, the main bearing of the crankshaft 50 has a pair of half bearings 51a and 51b, and the pair of half bearings 51a and 51b have split surfaces 51c and 51b.
The central axis A of the cylinder 52 with respect to the line B connecting 51d
Is given an inclination angle θ of less than 90 degrees. Such an inclination angle θ of the cylinder 52 tends to be set gradually smaller under the request of downsizing the engine room,
The number of design cases in which the inclination angle θ is about 10 to 60 degrees is increasing.

[0003]

However, in the structure of such a conventional in-line engine, the direction of rotation of the crankshaft 50 on the left side is indicated by the arrow X with the tilted cylinder 52 on the right side. It is set clockwise as shown. Then, the pair of half bearings 51a, 5
There is a technical problem that abnormal friction, seizure, tapping, etc. are likely to occur on the sliding friction surface 1b.

That is, in the design stage of the conventional in-line engine, the axial center locus of the main bearing portion of the crankshaft 50 is calculated to be about 180 with respect to the inclination angle θ during the explosion stroke.
The crankshaft 50 stagnates in the opposite direction, that is, in the half bearing 51b near the extension of the central axis A of the cylinder 52.

However, the present inventor has found that the peak of the explosion pressure has a delay of about 10 degrees with respect to the dead point of the explosion, so that the axial center locus of the portion where the crankshaft 50 is stagnant and a large load acts, Actually, the rotation direction X of the crankshaft 50
It was learned that it was shifted by the same angle as the delay of the peak of the explosion pressure. This shift direction is a direction further approaching the one split surface 51c of the pair of half bearings 51a and 51b which are inevitably close to each other based on the inclination angle θ of the cylinder 52. Thus, since the lubricating oil easily escapes from the split surface 51c, an oil film having a predetermined thickness is not retained at the portion where the crankshaft 50 is stagnant, and metal contact between the crankshaft 50 and one half bearing 51b occurs. However, the half bearing 51b will suffer from abnormal wear, seizure, and tapping noise.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional technical problems, and has a structure in which a main bearing of a crankshaft has a pair of half bearings. In the structure of an in-line engine in which the center axis of the cylinder forms an inclination angle of less than 90 degrees with respect to the line connecting the split surfaces of the half bearing, the left side crankshaft shifts with the inclined cylinder on the right side. It is the structure of an in-line engine that sets the rotation direction counterclockwise.

[0007]

In general, the peak of the explosion pressure in the cylinder has a delay of about 10 degrees with respect to the dead point of the explosion, so that the portion of the main bearing where the crankshaft is stagnant is oriented in the direction of rotation of the crankshaft. It is displaced from the position corresponding to the explosion dead center by the same angle as the delay of the explosion pressure peak.

Since the rotation direction of the crankshaft shaft is set counterclockwise with the inclined cylinder on the right side, this displacement direction moves away from the split surface of the half bearing in which the oil film is not well formed. Direction. In other words, it is a direction away from one of the split surfaces of the pair of half bearings that will inevitably come close to each other based on the inclination angle of the cylinder.

Thus, the lubricating oil escapes from the split surface, the oil film having the predetermined thickness is not retained, and the metal contact between the crankshaft and one of the half bearings is well suppressed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show an embodiment of the present invention. In FIG. 1 showing an outline of an in-line engine, reference numeral 1 is a cylinder, and a piston 2 is fitted in the cylinder 1 so as to freely move in the direction of the central axis A. A small end portion of the connecting rod 4 is swingably connected to the piston 2 by a piston pin 3, and a large end portion of the connecting rod 4 is divided into a pair of semi-cylindrical shapes. Half bearing 5
The crankpin 6a of the crankshaft 6 is rotatably supported by interposing a and 5b.

The journal 6b of the crankshaft 6 is
As shown in FIGS. 2 and 3, the pair of semi-cylindrical half bearings 7a and 7b, which are main bearings, are rotatably supported in the main bearing housing 8. The main bearing housing 8 is divided into a main housing 8a and a sub housing 8b, and half bearings 7a and 7b shown in FIG. 4 are fitted to the main housing 8a and the sub housing 8b so that the journal 6b of the crankshaft 6 is rotatably supported. The sub-housing 8b is fixed to the main housing 8a with bolts 9a and 9b. B indicates a line connecting the split surfaces 7c and 7d of the pair of half bearings 7a and 7b, and 7e is a claw for positioning the half bearings 7a and 7b.

Reference numeral 10 is an oil hole formed in the main housing 8a, and lubricating oil supplied from the outside to the oil hole 10 is an annular oil groove 11 formed on the fitting surfaces of the pair of half bearings 7a, 7b. The oil holes 12a of the half bearings 7a, 7b,
It is supplied from 12b to the sliding friction surface. Half bearing 7
The lubricating oil supplied to the sliding friction surfaces of a and 7b is supplied from the oil hole 13 of the crankshaft 6 to the connecting rod 4.
Is supplied to the sliding friction surfaces of the half bearings 5a and 5b at the large end of the piston, and is further used for lubricating the piston pin 3 and the like.

In the serial engine having such a structure, the split surfaces 7c, 7 of the pair of half bearings 7a, 7b are also provided.
The central axis A of the cylinder 1 is inclined at a predetermined angle with respect to the line B connecting the d and the vertical line C, and the line B connecting the split surfaces 7c and 7d of the pair of half bearings 7a and 7b as shown in FIG. On the other hand, the central axis A of the cylinder 1 has an inclination angle θ.
Here, 0 degree <θ <90 degrees. Further, the rotation direction Y of the crankshaft 6 is set counterclockwise with the inclined cylinder 1 on the right side.

Next, the operation will be described. When the in-line engine having the above structure is operated, each stroke of intake, compression, explosion and exhaust is repeated, and the linear reciprocating motion of the piston 2 in the direction of the central axis A causes the crankshaft 6 to rotate via the connect rod 4. Converted to rotational movement in direction Y.

During the operation of such an in-line engine, the peak of the explosion pressure in the cylinder 1 has a delay of about 10 degrees with respect to the explosion dead center as described above, so that the crankshaft 6 in the main bearing 6 has a delay. The portion where stagnation is displaced from the position corresponding to the explosion dead center by the same angle as the delay of the peak of the explosion pressure in the rotation direction Y of the crankshaft 6. That is, the position b at which the explosion pressure shows a peak and a large load is applied to the one half bearing 7b is about 10 degrees from the position a corresponding to the explosion dead center in FIG.
Will be displaced.

However, since the rotation direction Y of the crankshaft 6 is set counterclockwise with the tilted cylinder 1 on the right side, the displacement direction is the half bearing 7a, in which the oil film is not well formed. The direction is away from the split surface 7c of 7b. That is, the pair of half bearings 7 that will inevitably come close to each other based on the inclination angle θ of the cylinder 1.
It is a direction away from one of the split surfaces 7c of a and 7b.

Thus, the lubricating oil escapes from the split surface 7c, the oil film having a predetermined thickness is not retained, and the metal contact between the crankshaft 6 and the one half bearing 7b is well suppressed. As a result, the pair of half bearings 7a, 7
b, in particular, one half bearing 7b in which the crankshaft 6 is stagnant is prevented from suffering problems such as abnormal wear, seizure, and tapping.

[0018]

As can be understood from the above description,
According to the structure of the serial engine according to the present invention, it is possible to favorably prevent abnormal wear, seizure, hammering, and the like from occurring in the half bearing, so that the inclination angle of the central axis of the cylinder is reduced and the engine is reduced. The room can be made more compact.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an in-line engine according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a bearing portion of the crankshaft.

FIG. 3 is a sectional view showing a main bearing of the crankshaft of the same.

FIG. 4 is a perspective view showing a half bearing of the same.

FIG. 5 is a diagram schematically showing a conventional in-line engine.

[Explanation of symbols]

1: Cylinder, 2: Piston, 3: Piston pin, 4:
Connected blade, 6: crankshaft, 6a:
Crank pin, 6b: Journal, 7a, 7b: Half bearing, 7c, 7d: Split surface, 8: Main bearing housing, 8
a: main housing, 8b: sub housing, 9a, 9b:
Bolts, A: central axis of cylinder, B: line connecting split surfaces, C: vertical line, θ: inclination angle, Y: direction of rotation of crankshaft.

Claims (1)

[Claims] 1. A serial bearing having a pair of half bearings in a main bearing of a crankshaft, and a center axis of a cylinder having an inclination angle of less than 90 degrees with respect to a line connecting split surfaces of the half bearings. In the structure of the engine, the structure of the in-line engine is characterized in that the rotation direction of the crankshaft on the left side is set counterclockwise with the inclined cylinder on the right side.