JPH0242164A - Unit swing engine for motorcycle - Google Patents

Abstract

PURPOSE:To facilitate the assembling of a crank shaft and simplify the structure of a case cover by dividing a unit case integrally formed with an engine into a case and the case cover and cantilever-supporting the crank shaft only on the case. CONSTITUTION:A unit swing engine A suspended with a rear wheel 4 is integrally formed with a unit case 10 storing a power transmission mechanism 9 and an engine 11. In this case, the unit case 10 is formed with a case 12 and a case cover 13 divided on the plane perpendicular to a crank shaft 36. A cylindrical bearing bass 37 extended in the axle direction is formed on the case 12. The crank shaft 36 is inserted from the crank chamber 20 side and rotatably cantilever-supported on the bearing bass 37 via a thrust bearing 38 and a ball bearing 39. The crank shaft 36 is supported only on the case 12, the assembling of the crank shaft 36 is facilitated, the structure of the case cover 13 is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a unit swing engine for a motorcycle, and more particularly to a unit swing engine for a motorcycle whose unit case has a simple structure.

[Prior Art] Some small-sized motorcycles are equipped with a unit swing engine that integrates, for example, a unit case that houses a power transmission mechanism and an engine that is a power source. The unit case of this unit swing engine is divided on a plane perpendicular to the crankshaft, and this pair of divided cases pivotally supports the engine's crankshaft and the shaft of the power transmission mechanism, and the power of the engine is transmitted to the crankshaft. The crankshaft that is removed after changing the reciprocating motion of the piston into a rotating motion) is
One end thereof is pivotally supported by one of the divided cases, and the other end thereof is supported by the other divided case.

[Problems to be Solved by the Invention] Therefore, each of the pair of split cases must be provided with a bearing to support the crankshaft, and the structure of both cases cannot be simplified, and it is difficult to reduce manufacturing costs. This has become an obstacle.

Furthermore, when assembling the crankshafts to the divided cases, it is necessary to assemble bearings and the like to each of the divided cases, and it is troublesome to assemble the crankshafts with their axes aligned.

For this reason, for example, if only one split case is provided with a bearing to support the crankshaft, the other split case will not require a bearing, making the structure simpler and cheaper, and solving the above problem. However, in this case, since the crankshaft is supported by one bearing, it is necessary to particularly devise a structure for the bearing of the crankshaft.

This invention was made in view of this point, and by supporting the crankshaft in a cantilever manner on the case, the support structure is simplified, and assembling performance is improved and manufacturing costs are reduced.
An object of the present invention is to provide a unit swing engine for a motorcycle whose bearing part can simply and reliably support a crankshaft.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a unit swing engine for a motorcycle in which a unit case accommodating a power transmission g1 structure is formed integrally with the engine. It is composed of a case divided by a plane perpendicular to the crankshaft and a case 5, and a substantially cylindrical bearing boss part is formed in this case, and at least two or more bearings are provided in this bearing boss part and on the case side. The crankshaft of the engine is cantilever-supported by a chisel.

[Function] In the unit swing engine for a motorcycle according to the present invention, the unit case is composed of a case and a case lid that are divided perpendicularly to the crankshaft, and the crank is operated only by the bearing boss portion of this case. The shaft is supported on a cantilever.

For this reason, the crankshaft is supported only by the case, and the assembly work is easy because it only needs to be assembled in one place. Also,
Since no support structure for the crankshaft is formed on the case lid, the structure of the case lid can be simplified and manufactured at low cost.

Furthermore, since the bearing structure of the crankshaft is supported by the substantially cylindrical bearing boss part on the case side, the structure of the bearing boss part is simple and can be manufactured at low cost. Since it is supported by more than one bearing, support strength can be ensured with a simple structure.

[Example] Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 shows a motor-type motorcycle to which the present invention is applicable. A front wheel 2 is suspended on a front fork 3 at the front of a body frame 1, while a rear wheel 4 is suspended at the rear via a unit swing engine A. In this unit swing engine A, the front bracket 5 is supported by the vehicle body frame 1 via a stay 6, and the rear bracket 7 is supported by the vehicle body frame 1 via a damper 8, so that it can swing.

As shown in FIGS. 2 to 4, this unit swing engine A includes a unit case 10 that houses a power transmission mechanism 9 and is integrally formed with an engine 11. This unit case 10 is composed of a case 12 and a case M13, which are divided along a plane perpendicular to the crankshaft. The case 12 is formed, for example, by die-casting, and includes an engine component, a power transmission mechanism housing part, a rear wheel support part, etc., and the case M13 is formed by, for example, sheet metal pressing, synthetic resin, etc. It is joined to the section and fixed with fastening means such as screws.

Engine 11 is a two-stroke engine, case 12
includes the cylinder 14 of the engine 11 and the crankcase 1.
5 are integrally formed, and a combustion chamber 16 of the cylinder 14 is provided with an ignition plug 17. A lid 18 is screwed onto the lower part of the crankcase 15 with bolts 19, and
A crank chamber 20 is formed. This crank chamber 20
is communicated with the combustion chamber 16 via a scavenging passage 21.

The crank chamber 20 is supplied with air-fuel mixture from the carburetor 22,
An air cleaner 23 connected to the carburetor 22 is connected to an air chamber 24 formed at the center inside the case 12. A filter 25 is provided at the opening of the air chamber 24 to introduce air from the unit case 10 into the intake system. Additionally, an exhaust passage 2 communicating with the combustion chamber 16 is provided.
Reference numeral 6 is formed in the case 12, and this exhaust passage 26 communicates with an extreme portion 27 formed with the case M13, and this extreme portion 27 extends rearward as shown in FIG. Expansion chambers 28, 2 of the muffler along the exhaust part 27
9.30 is formed, and the exhaust from the exhaust part 27 passes sequentially from the expansion chamber 28 on the rear wheel side of the muffler, is introduced into the expansion chamber 30 on the front side, and is discharged to the outside from the exhaust hole 31. ing.

Cooling fins 32 and 33 are formed in the vicinity of the exhaust passage 26 and cylinder 14 of this exhaust system to cool them with air.

A piston 34 is provided in the cylinder 14 so as to be able to reciprocate and is connected to a crankshaft 36 via a connecting rod 35, and the crankshaft 36 is rotatably cantilevered by a bearing boss 37 of the case 12. The bearing boss portion 37 of the case 12 is substantially cylindrical and extends long in the axle direction.
6 is inserted therethrough, and is rotatably supported in a cantilever manner via a thrust bearing 38 and a ball bearing 39. This bearing boss portion 37
In this embodiment, two bearings are provided to improve the support strength, but two or more bearings may be provided.

This crankshaft 36 is equipped with a power generation device (flywheel magneto) 40, and this power generation device 40 is installed in the case 1.
The bearing boss portion 37 of No. 2 is provided in close proximity to the bearing boss portion 37 of No. 2 to reduce the size of the device. That is, by using the thrust bearing 38 for the bearing boss portion 37 of the case 12, the length in the axial direction is ensured to provide support strength, and the diameter of the bearing boss portion 37 is prevented from increasing. A charge coil 42 and a balsa fill 43 are arranged on this bearing boss portion 37 via a bracket 41.
, a permanent magnet 44 placed opposite the balsa coil 43
A flywheel 45 having a shape is rotatable together with the crankshaft 36. A gear 46 is formed on the outer periphery of the flywheel 45 to drive an auxiliary machine (not shown) such as an oil pump. Further, 6. the crankshaft 36 is provided with a one-way clutch 47, and this one-way clutch 47 is provided with a starter (not shown).

Further, the crankshaft 36 is provided with pulleys 48 and 49, and the pulley 49 is fixed to the crankshaft 36.
8 is moved in the axial direction on the crankshaft 36 by the operation of the centrifugal weight 5o, and the distance from the pulley 49 is changed.

A rotating shaft 52 that is rotated by a kick pedal 51 of a kick starter used in an emergency, for example, is supported between the case 12 and the case lid 13, and a fork 53 fixed to this rotating shaft 52 is attached to the tip of the crankshaft 36. A diving member 55 supported by the case i13 via a support shaft 54 is rotated at a position facing the case i13. A thread is formed on the support shaft 54, and this diving member 5
S moves by rotation, engages pulley 49, rotates crankshaft 36, and engine 1! When the engine 11 is started, the diving member 55 is returned to the initial position by the spring 56.

A coil spring 57 is attached to the rotating shaft 52, one end 57a of which is engaged with the case 12, the other end 57b of which is engaged with the fork 53, and the kick pedal 57 is engaged with the case 12.
1 is always returned to its initial position.

An intermediate case 58 is tightened and fixed to the rear wheel side of the case 12 with screws 59. A bearing boss portion 60 is formed on this intermediate case 58, and an intermediate shaft 61 is rotatably supported on this bearing boss portion 6o. has been done. This intermediate shaft 61 has a pulley 62.6.
3, the pulley 62 rotates together with the intermediate shaft 61, and this pulley 63 moves in the axial direction on the intermediate glaze 61, and is always urged in the direction of the pulley 62 by a spring 64. .

A belt 65 is stretched between the pulleys 62, 53 of the intermediate shaft 61 and the pulleys 48, 49 of the crank@36, and the rotational force from the crankshaft 36 is transferred to the intermediate shaft 61 steplessly and smoothly. transmission, and then deceleration is performed to obtain a predetermined gear ratio.

A gear 66 is formed at the end of this intermediate shaft 61,
This gear 66 is a gear 6 formed on the inner circumference of the rotating body 67.
7a to achieve secondary deceleration.

This rotating body 67 is integrated with an axle 68 of the rear wheel 4 by metal flow molding, and this axle 68 is rotatably supported by a bearing boss portion 69 of the case 12. The inner end of the axle 68 is supported by the intermediate case 58 via a ball 70, and receives thrust force from the ball 70. Further, the rear wheel 4 is provided at the outer end of the axle 68 so as to be rotatable therewith. Furthermore, the bearing boss portion 69 of the axle 68
is provided with a drum brake 71, and by operating a camshaft 72, the brake surer 3 expands using an anchor pin 74 as a fulcrum and slides into contact with a drum 75 that rotates together with the rear wheel 4 to perform braking. It has become.

[Effects of the Invention] As described above, the unit swing engine of the present invention includes a unit case that is divided into a case and a case lid in a plane orthogonal to the crankshaft, and a bearing boss portion formed on the case. Since the crankshaft is cantilever-supported, the crankshaft is supported only by the case, and the crankshaft can be assembled in just 1 wjl, making the assembly work easy. Also,
Since no support structure for the crankshaft is formed on the case lid, the structure of the case lid can be simplified and manufactured at low cost.

Further, since the bearing structure of the crankshaft is supported by the substantially cylindrical bearing boss portion on the case side, the structure of the bearing boss portion is simple and can be manufactured at low cost. Furthermore, since the bearing boss portion is supported by at least two bearings, support strength can be ensured even with a simple structure.

[Brief explanation of the drawing]

Figure 1 is a side view of the motorcycle, Figure 2 is a sectional view of the unit swing engine of this motorcycle, and Figure 3 is a side view of the unit swing engine with the case lid removed.
FIG. 4 is a partially cutaway rear view of the unit swing engine. In the drawing, reference numeral A indicates a unit swing engine, 10 a unit case, 11 an engine, 12 a case, 13 a case lid, 36 a crankshaft, and 37 a bearing boss.

Claims (1)

[Claims] In a unit swing engine for a motorcycle in which a unit case housing a power transmission mechanism is formed integrally with the engine, the unit case is composed of a case and a case lid that are divided in a plane orthogonal to the crankshaft, and A unit for a motorcycle, characterized in that a substantially cylindrical bearing boss is formed in the case, and the crankshaft of the engine is cantilever-supported within the bearing boss by at least two bearings and only by the case side. swing engine.