JPH0746619Y2 - Two-cycle engine crankshaft device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a crankshaft device for a two-cycle engine mounted on a small motorcycle or the like.

[Conventional technology and its problems]

A small motorcycle may be provided with a starting clutch that is a rotational speed-dependent centrifugal clutch in order to facilitate driving operation. In addition, an engine starting device using a starter motor may be provided to facilitate starting. In addition, a tachometer may be provided so that the engine speed can be known. In such a case, the starting clutch and the starter clutch need to be provided on the crankshaft. Also, a tachometer gear for extracting the engine rotation is provided on the crankshaft for accurate measurement. And if these are provided on one of the crankshafts,
There is a problem that the width of the engine becomes large.

It should be noted that the other side of the crankshaft is equipped with a generator for performing ignition and the like and a cooling fan for forced air cooling, so that there is no room for mounting other things. A multi-stage gear transmission is provided on the rear side, and when the number of transmission gears is increased to increase the number of transmission stages, the width of the transmission chamber portion of the engine case becomes larger, and accordingly, the total width of the engine is further increased. Becomes larger,
It is not convenient because it protrudes to the left and right.

Also, since the crankshaft is a large part in itself, it is very troublesome and costly to finish the cylindrical fitting surface precisely in order to improve the accuracy of shaft fitting with each part. Is a well-known matter. Therefore,
Simply fitting each component to the crankshaft cannot avoid the trouble of increasing the fitting accuracy, resulting in an increase in cost.

[Purpose of device]

This invention has been made to solve the above-mentioned conventional problems, and the accuracy control of the fitting surface of the ring gear and the primary pinion may be performed by the accuracy control of the tubular portion. This can be performed more easily than the accuracy control of the outer surface of itself, and the accuracy of the mating surface can be easily improved to improve assembly accuracy, and the crankshaft protrusion length can be shortened. It is an object of the present invention to obtain a crankshaft device for a two-cycle engine that can reduce the width of the engine and can reduce the number of parts and the cost without a single spacer or the like.

[Means for solving problems]

In order to achieve the above object, the present invention rotatably mounts a crankshaft on a crankcase wall of an engine case through a bearing, and provides a crankshaft extension extending from the crankcase to one outside. Are a ring gear and a one-way clutch that transmit the driving force of the starter motor to the crankshaft, a starting clutch that engages when the crankshaft reaches a certain number of revolutions, and a crankshaft drive that is fixed to the output side of the starting clutch. A crankshaft device for a two-cycle engine, comprising a primary pinion for transmitting a force to a speed change gear, and a retainer and a start clutch for a one-way clutch that rotate integrally with the crankshaft. Fixed to both side ends of the crankshaft between the retainer and the starting clutch,
A tachometer gear having a tubular portion formed at both ends is rotatably fitted with a crankshaft, and an inner peripheral surface of the ring gear is rotatably supported by one tubular portion of the tubular portion. The crankshaft device for a two-cycle engine is characterized in that the inner peripheral surface of the primary pinion is rotatably supported by the other side tubular portion, and the tachometer pinion is meshed with the tachometer gear.

[Action]

According to the present invention, the retainer and the starting clutch of the one-way clutch, which rotates integrally with the crankshaft, are fixed to the crankshaft extension extending outward from the crank chamber wall, respectively, at both ends of the crankshaft extension. , A crankshaft between the retainer and the starting clutch is fitted with a tachometer gear having tubular portions formed at both ends in rotation integrally with the crankshaft, and the tachometer gear is used as a spacer instead of a spacer. Since this can be omitted, it is possible to take out the engine rotation while making the disposition member on the crankshaft compact and shortening the crankshaft.

Here, considering that when the ring gear and the primary pinion are axially fitted to the crankshaft, considering that the surface of the crankshaft is made smooth to form a fitting surface, the crankshaft is a large part, so precision control is difficult. It is troublesome, the parallelism between the crankshaft, the ring gear and the primary pinion is difficult to manage, and it takes a lot of cost to obtain accuracy. On the other hand, according to the present invention, the inner peripheral surface of the ring gear is rotatably supported by the one cylindrical portion of the cylindrical portion and the inner peripheral surface of the primary pinion is rotatable by the other cylindrical portion. Since the tachometer pinion is engaged with the tachometer gear, the tubular portions on both sides can be used as a fitting surface for the crankshaft and the ring gear and the primary pinion. In addition, the accuracy control of the cylindrical part, which is a small component, is much easier than the accuracy control of the crankshaft, and the parallelism of the cylindrical part with the ring gear and the primary pinion is easy to control, and the accuracy control is easy. There is no cost to you. Further, since the accuracy of the fitting surface can be easily improved, the assembling accuracy can be improved.

〔Example〕

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

FIG. 1 shows a main part of a crankshaft device for a two-cycle engine according to this embodiment. FIG. 2 is a horizontal sectional view along the crankshaft, FIG. 2 is a horizontal sectional view along the crankshaft showing the entire engine case, and FIG. 3 is a sectional view perpendicular to the crankshaft showing the entire engine case.

As shown in FIGS. 1 to 3, in the crankshaft device of the embodiment, the crankshaft 1 is rotatably mounted on the crank chamber wall 3a of the engine case 3 with the bearing 2 interposed therebetween. Side cases 4 are connected to both sides of the engine case 3. Both ends 1a and 1b of the crankshaft 1 are crank chambers.
A ring gear 12 and a one-way clutch for transmitting the driving force of the starter motor 17 to the crankshaft 1 are provided at an end portion (crankshaft extension portion) 1a of the crankshaft 1 that extends to the outside of the crank chamber 32 and extends outward from the crank chamber 32. (Ring gear boss 12a, one-way roller 15, starter clutch hub 7, retainer 5, etc.) 33, a starting clutch 21 that engages when the crankshaft 1 reaches a certain speed or more, and an output side of the starting clutch 21 (starting A primary pinion 13 that is fixed to the clutch housing 19) and transmits the driving force of the crankshaft 1 to the transmission gear 24 is mounted on the shaft, and the retainer 5 of the one-way clutch 33 that rotates integrally with the crankshaft 1 and the starting clutch. 21 are respectively fixed to both ends of the crankshaft extension 1a in the direction of the crankshaft 1 and the retainer 5
A tachometer gear 10 having tubular portions 11a and 11b formed at both ends thereof is rotatably fitted to the crankshaft 1 between the crankshaft 1 and the start clutch 21 and one side of the tubular portion. The inner peripheral surface 12b of the ring gear 12 is rotatably supported by the tubular portion 11a, and the inner peripheral surface 13a of the primary pinion 13 is rotatably supported by the other tubular portion 11b. The tachometer pinion 14 is meshed with the ten.

That is, the ring gear 12 is rotatable with respect to the crankshaft 1 and is fixed to the motor driving force input side of the one-way clutch 33 (the boss portion 12a of the ring gear) to output the motor driving force of the one-way clutch 33. The side tubular portion 6 is fixed to the crankshaft 1 in the rotational direction.

The clutch retainer 5 is provided with a tubular portion 6 on the inner side, and a starter clutch hub 7 is fastened and coupled to the outer side. The clutch retainer 5 is inserted into the crankshaft 1 and locked with the key 8 so that the inner end of the tubular portion 6 contacts the inner end of the bearing 2.
An oil seal 9 is provided between the engine case 3 and the outer circumference of the tubular portion 6.
To provide.

The tachometer gear 10 is located between the ring gear 12 and the primary pinion 13, and from both ends in the direction of the crankshaft 1 of the tachometer gear 10, cylindrical portions 11a and 11b whose outer surfaces are formed into a cylindrical surface form a ring. The ring extends by being located between the inner peripheral surfaces 12b and 13a of each of the gear 12 and the primary pinion 13 and the outer peripheral surface of the crankshaft 1, and the one side tubular portion 11a of the tubular portions 11a and 11b causes the ring. Gear 1
The inner peripheral surface 12b of the second member 2 is rotatably supported, and the inner peripheral surface 13a of the primary pinion 13 is rotatably supported on the other side tubular portion 11b. In addition, the bush 1 is provided on each of the inner peripheral surface 12b of the boss 12a of the ring gear 12 and the inner peripheral surface 13a of the primary pinion which circumscribes the cylindrical portions 11a and 11b.
2c and 13b are mated.

In addition, the tachometer gear 10 is inserted into the crankshaft 1 so as to rotate integrally with the spline, and the tachometer gear 10
The tachometer pinion 14 is meshed with 10, and is connected to a tachometer (not shown) with a cable.

A one-way roller 15 is provided between the starter clutch hub 7 and the ring gear 12, and the ring gear 12 meshes with a pinion 18 of a starter motor 17 via an idler 16. In the primary pinion 13,
The starting clutch 21 is connected to the starting clutch housing 19 and the shoe 20 is spread at the tip of the crankshaft 1 by the centrifugal force.
Fasten. Starting clutch 21 and starting clutch housing
There is also a one-way 22 between the 19th. The rear portion of the engine case 3 is a transmission chamber 23, and two transmission shafts 25 meshing with a row of transmission gears 24 are mounted on the transmission casing 23. A primary gear 26 is connected to the end of the front speed change shaft 25 and meshes with the primary pinion 13. Inside the primary gear 26, a shut-off clutch for shutting off at the time of shifting is built in. A sprocket 27 for taking out an output is fixed to an end of the rear speed-change shaft 25, and connects a chain. A kick shaft 28 is mounted on the rear side of the speed change shaft 25.
A kick gear 29 of 28 is meshed with one of the speed change gears 24. The kick shaft 28 and the kick gear 29 are one-way clutches that mesh only in one direction. Crankshaft 1 extending to the other side
A generator 30 is attached to the extension portion 1b of, and a cooling fan 31 for forced cooling is attached to the outside of the generator 30.

The operation of the embodiment will be described below.

When starting the engine, starter motor 17 from pinion 18 through idler 16 to the ring gear
12 is rotated, the starter clutch hub 7 is rotated by the one-way roller 15, the crankshaft 1 is cranked, and the engine is started. The rotation of the crankshaft 1 is
The tachometer gear 10 is transmitted to the tachometer pinion 14, and the number of revolutions is displayed on the tachometer. When the rotation of the engine is increased, the shoe 20 of the starting clutch 21 is expanded by the centrifugal force, the rotation is transmitted to the starting clutch housing 19, and the rotation is transmitted to the primary pinion 13 and the primary gear 26 to be driven. When switching the transmission gear 24, the disconnecting clutch in the primary gear 26 is disengaged. Since the engine start is performed by the starter motor 17, the kick shaft 28 normally does not need to be used. However, in an emergency such as when the battery is exhausted, turning the kick shaft 28
The kick gear 29 is rotated, the primary gear 26 is rotated via the speed change gear 24, the primary pinion 13 is rotated, the start clutch housing 19 and the start clutch 21 are connected by the one-way 22, and the crankshaft 1 can be cranked to start. .

Further, from both ends of the tachometer gear 10 in the direction of the crankshaft 1, tubular portions 11a and 11b are formed between the inner peripheral surface of the ring gear 12 and the primary pinion 13 (via the bushes 12c and 13b) and the outer peripheral surface of the crankshaft 1. The inner peripheral surface 12b of the ring gear 12 is rotatably rotatably supported by the one side tubular portion 11a of the tubular portions 11a, 11b so as to be positioned in the other side tubular portion 11b. Since it is arranged so as to rotatably support the inner peripheral surface 13a of the pinion 13, the ring gear
The quality control of the mating surfaces with the 12 and the primary pinion 13 may be performed by the quality control of the outer surfaces of the cylindrical portions 11a and 11b, so that it is easier than the quality control of the outer surface of the crankshaft 1 itself. It can be carried out. Further, since the accuracy of the fitting surface can be easily improved, the assembling accuracy can be improved. Further, the tubular portion 6 of the clutch retainer 5 receives the oil seal 9, so that the crankshaft 1 can be shortened. In addition, the tachometer gear 10 has the tubular parts 11 on both sides.
Ring gear 12 primary pinion by a, 11b
13 is attached to the shaft and also serves as an axial spacer, and the axial length from the ring gear 12 to the tachometer gear 10 and the primary pinion 13 can be shortened. In this way, the length of the crankshaft 1 can be shortened and the width of the engine can be reduced. Further, since there is no separate spacer, the number of parts can be reduced, the cost can be reduced, and the assembling accuracy can be improved.

[Effect of device]

As described above, according to the present invention, the inner peripheral surface of the ring gear is rotatably rotatably supported by the one side tubular portion of the tubular portions at both ends in the crankshaft direction of the tachometer gear and the other side tubular portion. Since the inner peripheral surface of the primary pinion is rotatably supported by the cylindrical portion, the accuracy control of the fitting surface between the ring gear and the primary pinion may be performed by the accuracy control of the tubular portion. This can be performed more easily than the accuracy control of the outer surface of the. Moreover, since the accuracy of the fitting surface can be easily improved, the assembling accuracy can be improved. Further, since the tachometer gear can be used instead of the spacer and the spacer can be omitted, the extraction length of the crankshaft can be shortened and the lateral width of the engine can be reduced. Further, since there is no single spacer or the like, the number of parts can be reduced and the cost can be reduced.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 shows a crankshaft device of a two-cycle engine according to this embodiment, which is a horizontal sectional view taken along the crankshaft, and FIG. 2 shows the entire engine case. FIG. 3 is a horizontal sectional view taken along the crankshaft, and FIG. 3 is a sectional view perpendicular to the crankshaft showing the entire case of the engine. 1 ... Crankshaft, 1a ... Crankshaft extension, 2 ... Bearing, 3 ... Engine case, 3a ... Crank chamber wall, 6 ... Cylinder, 7 ... Starter clutch hub, 10 ...
… Tachometer gear, 11a, 11b …… Cylindrical part, 12 …… Ring gear, 13 …… Primary pinion, 19 …… Starting clutch housing, 21 …… Starting clutch, 32 …… Crank chamber, 33 …… One-way clutch

Claims (1)

[Scope of utility model registration request] 1. A crankshaft rotatably mounted on a wall of a crankcase of an engine case via a bearing, and a crankshaft extension extending from the crankcase to the outside to one side,
A ring gear and a one-way clutch that transmit the driving force of the starter motor to the crankshaft, a starting clutch that engages when the crankshaft reaches a certain number of revolutions, and a driving force of the crankshaft that is fixed to the output side of the starting clutch. A crankshaft device for a two-cycle engine, comprising a primary pinion for transmitting to a speed change gear and a primary pinion, respectively, wherein a retainer and a starting clutch of a one-way clutch rotating integrally with the crankshaft are provided on both sides of the crankshaft extension. While being fixed to the end, the crankshaft between the retainer and the starting clutch, the tachometer gear having a tubular portion formed at both ends is fitted integrally with the crankshaft in rotation.
Moreover, the inner peripheral surface of the ring gear is rotatably supported on one cylindrical portion of the cylindrical portion, and the inner peripheral surface of the primary pinion is rotatably supported on the other cylindrical portion. A crankshaft device for a two-cycle engine, characterized in that a tachometer pinion is meshed with a meter gear.