JPH0241994A - Unit swing engine of motorcycle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 a unit case that houses a power transmission mechanism that transmits power to an axle and an engine that is a power source.

The unit case of this unit swing engine is divided into left and right parts on a plane perpendicular to the crankshaft, and the pair of divided cases pivotally support the engine crankshaft, the intermediate shaft of the power transmission mechanism, etc.

In particular, the intermediate shaft of the power transmission mechanism that transmits the power of the engine to the axle has, for example, one end pivotally supported by one split case and the other end supported by the other split 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 intermediate shaft of the power transmission mechanism, and the structure of both cases cannot be simplified, resulting in a reduction in manufacturing costs. This poses an obstacle to efforts to reduce these emissions.

Furthermore, when assembling the intermediate shaft to the split case, it is troublesome to align the shaft centers and assemble the intermediate shaft, and high accuracy is required for machining the shaft centers.

This invention has been made in view of the above, and is a motorcycle unit that simplifies the support structure, improves assemblability, and reduces manufacturing costs by cantilevering the intermediate shaft of the assist transmission mechanism to the case. The purpose is to provide a swing engine.

[Means for Solving the Problems] In order to solve the above problems, the present invention includes a power transmission mechanism that transmits power from an engine shaft to an axle via an intermediate shaft, and a unit case that houses this power transmission mechanism. In a motorcycle unit swing engine in which the unit case is formed integrally with the engine, the unit case is composed of a case and a case lid that are divided in a plane perpendicular to the intermediate shaft, and a substantially cylindrical bearing is mounted on the case side. It is characterized in that a boss portion is provided, and the intermediate shaft of the power transmission mechanism is cantilever-supported only on the case side.

[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 in a plane orthogonal to the crankshaft, and a bearing boss is provided on this case, and only the case side is provided with a bearing boss. The intermediate shaft of the power transmission mechanism is supported in a cantilever manner. In this way, the crankshaft is supported only on the case side, and the intermediate shaft only needs to be assembled at one location, making the assembly work easy. Furthermore, since no support structure for the intermediate shaft 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 intermediate shaft of the power transmission mechanism is supported by the cylindrical bearing boss portion on the case side, the bearing structure is simple and can be manufactured at low cost.

[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 applied. 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 and an intermediate shaft (described later).The case 12 is, for example, die-cast and has an engine component part and a power transmission mechanism housing part. The case M13 is made of pressed sheet metal, synthetic resin, etc., and the case lid 13 is joined to the opening of the case 12 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 to close it off.
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.
6 is formed in the case 12, and this exhaust passage 26 is connected to an extreme portion 27 formed with the case M13, and this extreme portion 27 extends rearward as shown in FIG. The expansion chamber 2 of the muffler is
8, 29, and 30 are formed so that the exhaust gas from the exhaust part 27 passes sequentially from the expansion chamber 28 on the rear wheel side, is introduced into the expansion chamber 30 on the front side, and is discharged to the outside from the exhaust hole 31. It has become.

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 rod 35, and the crankshaft 36 is rotatably supported by a bearing boss 37 of the case 12 in a cantilevered manner. The bearing boss portion 37 of the case 12 is substantially cylindrical and extends long in the axle direction. The crankshaft 36 is inserted into the bearing boss 11537 from the crank chamber 20 side and rotates via the thrust bearing 38 and the ball bearing 39. Cantilevered.

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 in 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 is connected to this bearing boss portion 37 via a bracket 41.
and a pulser coil 43 are arranged, and this charge coil 4
2. Permanent magnet 4 placed opposite to pulser coil 43
A flywheel 45 having a number 4 is rotatable together with the crank @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, 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, the pulley 49 is fixed to the crankshaft 36, 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 is supported between the case 12 and the case i13, and a fork 53 fixed to the rotating shaft 52 is connected to the tip of the crankshaft 36. opposite·
At this position, the diving member 55 supported by the case M13 via the support shaft 54 is rotated.

The support shaft 54 is threaded, and the plunge member 55 moves by rotation, engages the pulley 49, rotates the crankshaft 36, and starts the engine 11. When the engine 11 starts, the plunge member 55 moves. is returned to its initial position by a spring 56.

A coil spring 5 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 5
1 is always returned to its initial position.

An intermediate case 58 is fastened and fixed to the rear wheel side of the case 12 with screws 59, and a substantially cylindrical bearing boss portion 60 is integrally formed in the intermediate case 58 by die casting, for example. An intermediate shaft 61 is cantilever-supported by the bearing boss portion 60 with its central portion rotatable, and the case 1 is supported only by the bearing boss portion 60.
An intermediate shaft 61 is pivotally supported on the second side.

Pulleys 62 and 63 are provided in this intermediate @61, and the pulley 62 rotates together with the intermediate shaft 61, and this pulley 63 moves in the axial direction on the intermediate shaft 61, and is always supported by a spring 64. It is biased in the pulley 62 direction.

Furthermore, the pulleys 62 and 63 of the intermediate shaft 61 and the crankshaft 3
A V-belt 65 is stretched between the pulleys 48 and 49 of No. 6, and smoothly transmits the rotational force from the crankshaft 36 to the intermediate shaft 61 without any steps, and then decelerates it to a predetermined gear ratio. is now available.

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.

In this way, the intermediate shaft 61 has its central portion rotatably supported in a cantilever manner by the bearing boss portion 60, power is input from the engine 11 side to one end thereof, and the rotating body 67 is connected to the other end. Since the power is output to the axle 68 side, and the input and output of power are performed by one intermediate shaft 61, it is only necessary to form the bearing boss portion 60 at one location on the intermediate case 58. is simple and improves machining accuracy.

Furthermore, for assembly, it is only necessary to assemble the intermediate shaft 61 to the intermediate case 58 fixed to the case, and there is no need to support it on the case M13 side, so there is no need to form a bearing boss when forming the case M13, and the case It becomes possible to form li3 by, for example, press processing, and processing costs can be reduced.

The power transmission mechanism at the input end of the intermediate shaft 61 may be configured, for example, by a gear mechanism, and the output side may also be configured by a gear mechanism, a belt mechanism, etc., and these power transmission means are not particularly limited.

Further, in this embodiment, the intermediate shaft 61 is provided in the intermediate case 58, but a bearing boss portion is provided in the case 12, and the case 1
2, the rotary body 67 is integrated with the axle 68 of the rear wheel 4 by metal flow formation, and this axle 68 is rotatably supported by the bearing boss portion 69 of the case 12. ing. A ball 7o is attached to the inner end of this axle 68.
It is supported by the intermediate case 58 via the ball 7o, and receives thrust force from the ball 7o. Further, the rear wheel 4 is provided at the outer end of the axle 68 so as to be rotatable therewith. Further, a drum brake 7 is provided on the bearing boss portion 69 of the axle 68.
1 is provided, and by operating the camshaft 72, the brake surer 3 is expanded using the anchor bin 74 as a fulcrum, and comes into sliding contact with a drum 75 that rotates together with the rear wheel 4 to perform braking. .

Note that the case of this invention is not limited to a completely integrally molded product;
Of course, it also includes a structure formed of a plurality of members and connected by a tightening means such as a bolt as in this embodiment.

[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 intermediate shaft, and a substantially sketch-shaped bearing on the case side. Since the intermediate shaft of the power transmission mechanism is cantilever-supported on the boss portion, the intermediate shaft is supported only by the case side, and the assembly work is easy because it only needs to be assembled at one location on the case side. Furthermore, since no support structure for the intermediate shaft is formed on the case lid, the structure of the case lid can be made PJJL, and it can be manufactured at low cost.

Further, since the bearing structure of the intermediate shaft of the power transmission mechanism is supported by the cylindrical bearing boss portion on the case side, the bearing structure is simple and can be manufactured at low cost.

[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.
′! Figure J4 is a rear view of the unit swing engine with a part cut away. In the figure, reference numeral A indicates a unit swing engine, 10 a unit case, 11 an engine, 12 a case, 13 a case lid, 58 an intermediate case, 60 a bearing boss, and 61 an intermediate shaft.

Claims (1)

[Claims] In a unit swing engine for a motorcycle, the unit case is equipped with a power transmission mechanism that transmits power from the engine shaft to the axle via an intermediate shaft, and the unit case housing this power transmission mechanism is formed integrally with the engine. Consisting of a case and a case lid that are divided along a plane perpendicular to the intermediate shaft, a substantially cylindrical bearing boss is provided on the case side, and the intermediate shaft of the power transmission mechanism is cantilever supported only on the case side. A unit swing engine for motorcycles that is characterized by: