JPH0874832A - Built-up crankshaft - Google Patents

Abstract

PURPOSE: To provide a built-up crankshaft whose usage life is elongated by enlarging press-fitting length of a crank journal without increasing a pitch between cylinders, improving strength against twisting torque, facilitating processing of a crank case, and reducing a moment of a bearing. CONSTITUTION: A stepped sleeve 26 to which a crank journal 20 is fitted under pressure is formed on a crank web 24 extendingly in an axial direction of a crank shaft 14. One bearing 28 is fitted to the stepped sleeve 26. An outer diameter of the bearing 28 is substantially the same that of the other bearing 30 is provided on the portion other than the stepped sleeve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembly type crankshaft, and in particular, increases the press-fitting length of a crank journal to make it stronger against torsional torque without increasing the pitch between cylinders, and at the same time, to improve the crankcase. The present invention relates to a prefabricated crankshaft that can be easily processed and can have a long service life.

[0002]

2. Description of the Related Art As an engine, there is a two-cycle engine that generates power by performing intake, compression, explosion and exhaust while a crankshaft makes one revolution. This two-cycle engine is often used in, for example, two-wheeled vehicles, outboard motors, snowmobiles, and the like.

Examples of the two-cycle engine include those shown in FIGS.

That is, in FIG. 4, 102 is a multi-cylinder two-cycle engine, 104 is a cylinder wall, 106 is a cylinder, 108 is a cylinder head, 110 is an upper crankcase, 112 is a lower crankcase, 114 is a crankshaft, 116 is a connecting rod, 11
Reference numeral 8 is a piston, and 106c is a cylinder center line.

The crankshaft 114 is pivotally supported by an upper crankcase 110 and a lower crankcase 112.

The crankshaft 114 is an assembly type, and the crank journal 120 is rotatably supported by a plurality of bearings 122 held by the upper crankcase 110 and the lower crankcase 112. It has a crank web 126 to which 124 is connected. Each bearing 12
No. 2 is in direct contact with the crank journal 120. The crank pin 124 has a connecting rod 1
One end side of 16 is pivotally supported. A piston 118 is provided on the other end side of the connecting rod 116.

In the two-cycle engine 102 of FIG. 4, the pitch between cylinders, which is the pitch between adjacent cylinder center lines 106c, is set to a predetermined length P ₁₀ .

In FIG. 5, 202 is a multi-cylinder 2-cycle engine, 204 is a cylinder wall, 206 is a cylinder, 208 is a cylinder head, 210 is an upper crankcase, 212 is a lower crankcase, 214 is a crankshaft, 216 is a crankshaft. A connecting rod, 218 is a piston, and 206c is a cylinder center line.

The crankshaft 214 is axially supported by an upper crankcase 210 and a lower crankcase 212.

The crankshaft 214 is an assembly type, and the crank journal 220 is axially supported by a plurality of bearings 222 held by an upper crankcase 210 and a lower crankcase 212, and the crank journal 220 is press-fitted and a crank pin is inserted. It has a crank web 226 to which 224 is connected. Each bearing 22
No. 2 is in direct contact with the crank journal 220. The crank pin 224 has a connecting rod 2
One end side of 16 is pivotally supported. A piston 218 is provided on the other end side of the connecting rod 216.

In the two-cycle engine 202 of FIG. 5, the crank web 2 of the crank journal 220 is
Crank web 226 to obtain press fit length into
A sleeve 228 having a length L ₁₁ extends in the axial direction of the crankshaft 214. Therefore, the inter-cylinder pitch P ₁₁ between the adjacent cylinder center lines 206c is set to be larger than the inter-cylinder pitch P ₁₀ shown in FIG. 4 by the length L ₁₁ .

In FIG. 6, 302 is a multi-cylinder 2-cycle engine, 304 is a cylinder wall, 306 is a cylinder, 308 is a cylinder head, 310 is an upper crankcase, 312 is a lower crankcase, 314 is a crankshaft, 316 is a crankshaft. A connecting rod, 318 is a piston, and 306c is a cylinder center line.

The crankshaft 314 is pivotally supported by an upper crankcase 310 and a lower crankcase 312.

The crankshaft 314 is an assembly type, and the crank journal 320 is rotatably supported by a plurality of bearings 322 held by the upper crankcase 310 and the lower crankcase 312, and the crank journal 320 is press-fitted and the crankpin 320 is pressed. It has a crank web 326 to which 324 is connected. Each bearing 32
No. 2 is in direct contact with the crank journal 320. The crank pin 324 has a connecting rod 3
One end side of 16 is pivotally supported. A piston 318 is provided on the other end side of the connecting rod 316.

In the two-cycle engine 302 of FIG. 6, the crank web 3 of the crank journal 320 is
Crank web 326 to obtain press fit length into
Is provided with a sleeve 328 having a length L ₁₂ extending in the axial direction of the crankshaft 314.
An oil seal material 330 is fitted and provided on the. Therefore, the cylinder pitch P ₁₂ between the adjacent cylinder center line 306c is set to be larger by a length L ₁₂ of the cylinder between the pitch P ₁₀ shown in FIG. 4, the oil seal member 3
Since 30 is fitted in the sleeve 328, the inter-cylinder pitch P ₁₂ is as small as possible.

In FIG. 7, reference numeral 402 is a multi-cylinder two-cycle engine, 404 is a cylinder wall, 406 is a cylinder, 408 is a cylinder head, 410 is an upper crankcase, 412 is a lower crankcase, 414 is a crankshaft, 416 is a crankshaft. A connecting rod, 418 is a piston, and 406c is a cylinder center line.

The crankshaft 414 is pivotally supported by an upper crankcase 410 and a lower crankcase 412.

The crankshaft 414 is an assembly type, and the crank journal 420 is rotatably supported by a plurality of bearings 422 held by the upper crankcase 410 and the lower crankcase 412. It has a crank web 426 to which 424 is connected. Each bearing 42
No. 2 is in direct contact with the crank journal 420. The crank pin 424 has a connecting rod 4
One end side of 16 is pivotally supported. A piston 418 is provided on the other end side of the connecting rod 416.

In the two-cycle engine 402 shown in FIG. 7, the crank web 4 of the crank journal 420 is used.
Crank web 426 to obtain a press fit length into
Is provided with a sleeve 428 having a length L ₁₃ extending in the axial direction of the crankshaft 414.
The labyrinth seal material 330 is provided by being fitted therein. Therefore, although the inter-cylinder pitch P ₁₃ between the adjacent cylinder center lines 406c is set larger than the inter-cylinder pitch P ₁₀ shown in FIG. 4 by the length L ₁₃ , the labyrinth seal material 430 is fitted to the sleeve 428. Since it is mounted, the inter-cylinder pitch P ₁₃ is as small as possible.

In FIG. 8, 502 is a multi-cylinder two-cycle engine, 504 is a cylinder wall, 506 is a cylinder, 508 is a cylinder head, 510 is an upper crankcase, 512 is a lower crankcase, 514 is a crankshaft, and 516 is a crankshaft. A connecting rod, 518 is a piston, and 506c is a cylinder center line.

The crankshaft 514 is pivotally supported by an upper crankcase 510 and a lower crankcase 512.

The crankshaft 514 is an assembly type, and the crank journal 520 is rotatably supported by a plurality of bearings 522 held by the upper crankcase 510 and the lower crankcase 512, and the crank journal 520 is press-fitted and the crankpin 520 is pressed. It has a crank web 526 to which 524 is connected. One end of a connecting rod 516 is pivotally supported by the crank pin 524. A piston 518 is provided on the other end side of the connecting rod 516.

In the two-cycle engine 502 of FIG. 8, adjacent crank journals 520 are connected by connecting tubes 528, and
The bearing 522 is fitted in the connecting tube 528.

An example of an assembly type crankshaft for such a two-cycle engine is, for example, Japanese Patent Laid-Open No. 58-58.
-28009, JP-A-2-42207, JP-A-58-16421, JP-A-59-43715.
No. 6,086,045. In the one disclosed in Japanese Patent Laid-Open No. 58-28009, the large end of the connecting rod, into which the plain bearing is inserted, is connected to the crank pin assembled to the crank web. It is intended to reduce the weight of the part. In the one described in JP-A-2-42207, a plain bearing is inserted into the large end of the connecting rod, the large end is connected to the crank pin of the crankshaft, and the plain bearing is made into an integral type. The inner diameter of the inner peripheral part is maximized in the part orthogonal to the axis connecting the small end and the large end to reduce the weight of the large end of the connecting rod and the finished mass, and prevent seizure. To do. In the one disclosed in Japanese Utility Model Laid-Open No. 58-16421, the crankshaft is rotatably supported in the crankcase through a plurality of ball bearings, and the outer race is fixed to the journal portion of the ball bearing by press fitting. A biasing member such as a spring that fits in the bearing hole of the crankcase and biases the outer race to one side in the axial direction is provided on at least one side surface of the ball bearing, and the biasing member is biased on the outer race outer surface of the remaining ball bearing. A stopper piece that opposes the force is provided. 59-437
The one described in Japanese Patent No. 15 has a deep counterbore hole in one half member that constitutes the outer ring, and the half members that constitute the outer ring are tightening holes having a polygonal cross section on the upper surface of the head. The bolt head is connected from the deep facing hole and the head portion of the bolt is housed in the deep facing hole.

[0025]

However, in the conventional assembly type crankshaft, in the case of the crankshaft 114 shown in FIG. 4, when the torsion torque at the press-fitting portion of the crank journal is insufficient, the thickness of the crank web is increased. It is necessary or necessary to configure the crankshaft 214 as shown in FIG.

In the case of the crankshaft 214 of FIG. 5, the inter-cylinder pitch P ₁₁ is the inter-cylinder pitch P _{10 of} FIG. 4 by the length L ₁₁ of the stepped sleeve of the crank web.
There was a problem that it became larger than.

The problem of the crankshaft 214 of FIG. 5 can be solved by the structure of the crankshafts 314 and 414 shown in FIGS. 6 and 7. However, in the case of the crankshafts 314 and 414 of FIGS. If the press-fitting length of the journal is required to be larger, it is difficult to deal with it.

Further, in the case of the structure of the crankshaft 514 of FIG. 8, there are two places where the torsion torque is received, which is inconvenient in that the whole structure becomes weaker than that of the crankshaft 114 of FIG.

Further, the crankshaft 3 shown in FIGS.
In Nos. 14 and 414, since the bearing is sealed from the crank chamber, lubrication by the air-fuel mixture cannot be expected, and there is a disadvantage that it is necessary to supply oil to this portion by an oil pump.

[0030]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention is rotatably supported between an upper crankcase and a lower crankcase of an engine to press fit a crank journal and connect a crank pin. In an assembled crankshaft provided with a crank web, a step sleeve into which the crank journal is press-fitted is provided in the crank web by extending in the axial direction of the crank shaft, and one bearing is fitted to the step sleeve. The outer diameter of the one bearing is substantially the same as the outer diameter of the other bearings other than the step sleeve.

[0031]

According to the structure of the present invention, since the bearing is fitted in the stepped sleeve, the press fit length of the crank journal is increased without increasing the pitch between the cylinders. In addition, since the outer peripheral surface of each bearing is located at the same level, machining of the crankcase is facilitated, and the bearings are arranged close to the cylinder center line side. The bearing moment is reduced and the service life can be extended.

[0032]

Embodiments of the present invention will be described in detail and specifically with reference to the drawings. 1 to 3 show an embodiment of the present invention. 1 and 3, 2 is a multi-cylinder 2-cycle engine, 4 is a cylinder wall, 6 is a cylinder,
8 is a cylinder head, 10 is an upper crankcase, 1
2 is a lower crankcase, 14 is a crankshaft, 1
6 is a connecting rod, 18 is a piston, and 6c is a cylinder center line.

The crankshaft 14 is pivotally supported by the upper crankcase 10 and the lower crankcase 12.

The crankshaft 14 is of an assembly type and has a crank web 24 into which the crank journal 20 is press-fitted and the crank pin 22 is connected. The crank pin 22 has a connecting rod 1
One end side of 6 is pivotally supported. A piston 18 is provided on the other end side of the connecting rod 16.

As shown in FIGS. 1 and 2, a step sleeve 26 into which the crank journal 20 is press-fitted is inserted into the two central crank webs 24 of the two-cycle engine 2 by a length L in the axial direction of the crankshaft 14. It is extended and provided respectively. This step sleeve 26, as shown in FIG.
It has an inner diameter D ₁ , an outer diameter D ₂ , and a thickness T, and is formed into an annular body.

A sleeve side bearing 28, which is one bearing, is fitted and provided on the step sleeve 26. The sleeve-side bearing 28 has a width substantially equal to the length L of the step sleeve 26, and has an inner diameter D ₃ sized to fit the outer peripheral surface of the step sleeve 26.

The crankshaft 14 is rotatably supported by a direct support bearing 30, which is another bearing that is in direct contact with the crankshaft 14. The direct support bearing 30 is formed such that the inner diameter D ₅ is fitted to the outer peripheral surface of the crank journal 20, and the outer diameter D ₆ is fitted to the inner peripheral surfaces of the upper and lower crankcases 10, 12. Is formed in.

In this embodiment, the outer diameter D ₄ of the sleeve side bearing 28 is formed to be substantially the same as the outer diameter D ₆ of the direct support bearing 30, that is, inside the upper and lower crankcases 10 and 12. The size is such that it fits on the peripheral surface and both outer peripheral surfaces are at the same level.

Next, the operation of this embodiment will be described.

In the two-cycle engine 2, the reciprocating motion of the piston 18 is converted into the rotary motion of the crankshaft 14 by the connecting rod 16 to extract the driving force.

By the way, in this embodiment, since the step sleeve 28 is provided on the crank web 24 and the sleeve side bearing 28 is provided on the step sleeve 26, the press fitting length of the crank journal 20 is sufficiently secured. As compared with the conventional crankshafts shown in FIGS. 6 and 7, the press-fitting length can be made sufficiently large, which makes it possible to make it stronger against torsional torque.

Further, in this way, the crank journal 2
Even if the length of 0 is increased, the adjacent cylinder center line 6c
The inter-cylinder pitch P which is the pitch between
It can be shortened compared to a crankshaft of 7.

Further, since the outer peripheral surfaces of the bearings 28 and 30 are located at the same level, the upper and lower crankcases 10 and 12 may be machined in the same cylinder. Therefore, the upper and lower crankcases 10 and 12 are processed. Processing becomes easy.

Furthermore, since the sleeve side bearing 28 is closest to the cylinder center line 6c, the bearing moment is reduced and the service life can be extended.

Further, since the sleeve side bearing 28 is structured to be lubricated with oil cyst, there is no need to separately supply oil by the oil pump for the sleeve side bearing 28,
The configuration can be simplified.

[0046]

As is apparent from the above detailed description, according to the present invention, the step sleeve into which the crank journal is press-fitted is provided in the crank web so as to extend in the axial direction of the crankshaft, and the step sleeve has one step sleeve. The bearings are fitted and the outer diameter of one bearing is made to be almost the same as the outer diameter of other bearings other than the stepped sleeve, so that the press fit length of the crank journal can be increased without increasing the pitch between cylinders. This makes it possible to make it stronger against torsional torque, and because the outer peripheral surfaces of each bearing are located at the same level, machining of the crankcase is easy, and further, the bearing is located on the cylinder center line side. The bearing moment is reduced, and the service life can be extended.

[Brief description of drawings]

FIG. 1 is a sectional view of a two-cycle engine.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a configuration diagram of a two-cycle engine.

FIG. 4 is a sectional view of a conventional two-cycle engine.

FIG. 5 is a cross-sectional view of a conventional two-cycle engine.

FIG. 6 is a sectional view of a conventional two-cycle engine.

FIG. 7 is a sectional view of a conventional two-cycle engine.

FIG. 8 is a sectional view of a conventional two-cycle engine.

[Explanation of symbols]

 2 2-cycle engine 10 upper crankcase 12 lower crankcase 14 crankshaft 20 crank journal 22 crankpin 24 crankweb 26 step sleeve 28 sleeve side bearing 30 direct support bearing

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[Procedure amendment]

[Submission date] November 8, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

FIG.

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

[Figure 7]

[Figure 8]

Claims (1)

[Claims] 1. A prefabricated crankshaft axially supported between an engine upper crankcase and a lower crankcase, comprising a crank web for press-fitting a crank journal and connecting a crank pin, wherein the crank web is provided with the crank. A step sleeve into which the journal is press-fitted is provided extending in the axial direction of the crankshaft, and one bearing is fitted into the step sleeve, and the outer diameter of the one bearing is provided other than the step sleeve. An assembled crankshaft, which is formed to have substantially the same outer diameter as other bearings.