JPS602235B2 - Motorcycle power unit suspension system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power unit suspension system for a motorcycle in which the lower front surface of the power unit and the vehicle body are pivotably connected to each other by a link to protect the lower surface of the engine.

The power unit swing mechanism integrates a case containing the engine and engine power transmission device, and pivots it to the vehicle body so that it can swing freely, forming part of the suspension system.The power unit swing mechanism is used as a drive and suspension system for motorcycles. It has been adopted.

This type of power unit swing mechanism has the front part on the engine side pivoted to the vehicle body, and the rear part pivoted to the vehicle body via the rear cushion unit. The road reaction force that passes through the rear wheels due to the bump acts on the power unit as a tensile force, etc.
This is transmitted to the vehicle body and impedes ride comfort. In order to improve the above problems, it has been proposed to connect the vehicle body and power unit with a link or to interpose an elastic body between them. It is difficult to obtain one that satisfies both followability.

On the other hand, since the engine of this type of motorcycle does not have a frame under it, it is exposed at the crosspiece, so if the engine runs over a large bump or obstacle on the road surface, the bottom of the engine may collide with the obstacle. , there is a risk of damaging the engine, and protection of the engine is desired.

The present inventors have devised the present invention to solve the above-mentioned problems.The purpose of the present invention is to pivotally connect the front part of the power unit and the vehicle body with a link so that the front part of the power unit can swing freely, and to attach the link to the vehicle body. A support member for pivotal support extends from the vehicle body, and the link and the lower surface of the power unit are exposed on the support member, and the support member has a width in the left-right direction and a length in the front-rear direction of a size necessary to cover the lower surface of the engine. To provide a power unit suspension system for a motorcycle, which is used as a protection member and protects the lower surface of an engine and a mounting portion from obstacles.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a side view of the rear part of the motorcycle, and the front part is omitted because it is already known.

There is a curved inverted L at the rear of the main frame 2 of the motorcycle 1.
A molding frame 3 is curved and extended upward and rearward, a seat 4 is attached thereon, and the frame is surrounded by a body frame 5 and a rear fender 6. Reference numeral 7 denotes a power unit, and the power unit 7 consists of an engine 8 installed upwardly in the front, a crankcase 9 below this, a transmission case 10 extending behind this, etc.
A transmission mechanism and the like are housed inside, and the whole unit constitutes a power unit, and a rear wheel 11 that forms the drive mechanism is supported at the rear of the transmission case 10.

A bracket portion 10a is protruded from the rear of the transmission case 10, to which the lower end of the rear cushion unit 12 is pivotally attached 12b, and the upper end of the rear cushion unit 12 is curved and extended upward and rearward of the rear frame 3. Pivotally attached 12a is attached to the protruding rear portion 3a. The rear cushion unit 12 is arranged so that the upper part faces forward and the lower part faces backward.
The center line N, is facing downwardly and at an angle to the road surface G. The front portion of the power unit 7 described above is pivotally connected to the lower front portion of the rear frame 3 on the vehicle body side via a link 13. The link 13 has left and right side plates 14, 14,
It is composed of a connecting piece 15 that structurally connects the rear parts of the rod, and a stopper rod 16 that is installed between the upper parts of the rear parts, forming a U-shape in plan view, and each part is integrally joined. Collars 17, 17 are fixed concentrically to the lower parts of the left and right side plates 14, 14 of the link 13, and a rubber bush 1 in which rubber is baked between the inner and outer rings 18a, 18b is attached to the inner diameter of the collars 17, 17.
8 outer rings 18b are arranged and held. A support member 26 extends rearward at the lower front part of the rear frame 3.
6 comprises left and right side plates 27, 27, and a bottom plate 28 which structurally connects the lower ends of the side plates 27, 27, and is made of a press-formed steel plate or the like, and is welded to the lower front part of the rear frame 3 so as to extend rearwardly. It has been extended.

The bottom plate 28 of the support member 26 is set to a size necessary and sufficient to cover the front lower surface of the power unit 7, that is, the lower surface of the crankcase 9 at the lower part of the engine. Inner rings 18a, 18a of the rubber bushing 18, in which a bolt forming the lower horizontal shaft 19 is inserted into the structure between the side plates 27, 27 of the support village 26, and the horizontal shaft 19 is iron-bonded to the left and right side plates 14, 14 of the link 13. nut 2 from one side of the side plate 27 through the
0, the lower part of the link is pivotally supported on the rear part of the bottom plate 28 of the support member 26.

On the left and right of the lower front part of the crankcase 9, projections ga, 9a having widthwise holes 9b are hung down, and the holes 9M of each projection 9a, 9a are rubber bushes with rubber applied to the inner and outer rings 21a, 21b. 21 is attached via the outer ring 21b, while a collar 24 is constructed between the upper front parts of the side plates 14, 14 of the link 13, and the inner ring 213 of the rubber bushes 21, 21 is attached.
Pass the bolt that forms the upper horizontal shaft 22 between them, and connect the horizontal shaft 22.
passes through the collar 24 between the side plates 14, 14, and is attached with a nut 23 from one protrusion side.

In this way, the link 13 and the front lower surface of the power unit are separated, and the support shafts 22 and 19, which are the upper and lower gutter attachment parts of the link 13, are separated from each other.
The upper part is biased toward the front and the lower part is biased toward the rear, and the center line N2 that connects these is moved downward and rearward, and the center line N2 is located at the rear and faces the road surface G. Nitz 12
parallel to, or less than parallel to, the center line N. Thus, the center line N2 of the link 13, the rear cushion knit 12,
The power unit 7 forms a pseudo-parallelogram link, and the lower surface of the engine of the power unit 7 faces onto the bottom plate 28 of the support member 26 while being pivotally supported by one end of the link.
constitutes a protective member.

In the above, the power unit 7 is easily moved in the front and back direction by the pseudo-parallelogram link composed of the link 13, the power unit 7, and the reaction unit 12, and the front part moves in the vertical direction around the lower horizontal axis 19 of the link 13. The wheels and power unit follow the road surface very smoothly, and the rubber bush 18 around the horizontal axis is preloaded with a preload that resists the rotation direction, so that the spring rate can be adjusted appropriately. The rubber bush can be set to compress and deform in the circumferential direction to absorb and attenuate vibrations caused by the longitudinal movement of the power unit, as well as vibrations caused by the main force in the longitudinal direction indicated by the arrows of the engine. Good followability can be maintained.

Also, when braking the rear wheel 11, the power unit 7 follows the braking and swings in the vertical direction of the link, causing the power unit 7 to follow the movement in the longitudinal direction, and the power unit 7 as a whole does not swing in the vertical direction. Due to the pseudo-parallelogram link structure including 13, the front and rear soft parts of the wheels 11 where the ground load of the tires is not applied also function as cushion rubber with a low spring rate, and the longitudinal movement and vibration of the power unit 7 are absorbed and damped by the tires. , it is possible to enhance the vibration absorption and damping effect as a whole and suppress vibration propagation to the vehicle body side, and furthermore, since the rubber bush 18 is used as a replacement,
While increasing the spring rate and setting the stiffness, sufficient followability and vibration damping effects can be obtained, and the life and durability of the rubber bush can be improved. By the way, the lower surface of the engine 8 is covered with the bottom plate 28 of the support member 26, so even if an obstacle hits this part, it will be protected by the bottom plate 28, and the engine and links will not hit the obstacle. However, the engine does not hit bumps on the road surface and is protected by the bottom plate 28. In addition, 25 in the drawing is the striker rubber, and rubber 2
5 is interposed between the link 13 and the front lower surface of the power unit 7, and compresses vibrations in the direction of the main excitation force of the engine, and stretches 25a.
5b to further improve vibration absorption and damping effects.As is clear from FIG. 3, since the reaction unit 12 is supported on the left side by a cantilever
It is provided under the highly rigid part on the left side of the power unit 7.

As is clear from the above, according to the present invention, the vehicle body and the
The support member of the link that connects the front part of the down tube covers the lower surface of the front of the engine, making it possible to protect the engine, which was often ignored in power unit type motorcycles, and allowing the engine to be mounted on the down tube. Like the type, it protects the engine from road obstacles and wheels falling off, etc., and by using the link support member, this can be achieved with a simple structure and without increasing the number of parts, and as mentioned above, there is less vibration. , it has many advantages such as being able to obtain a power unit suspension system with excellent followability.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view of the rear part of the motorcycle, FIG. 2 is a side view with a major section cut away, and FIG. 3 is a cutaway plan view of the same. In the drawings, 1 is a motorcycle, 2 and 3 are a vehicle body, 7 is a power unit, 8 is an engine, 9 is a crankcase, 10 is a transmission case, 12 is a rear cushion unit, 13 is a link, and 26 is a support member. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. The vehicle body and the front part of the power unit, which integrates the engine, crankcase, transmission case, etc., are pivotally connected by a link, and the rear part of the power unit and the vehicle body are connected by a rear action unit. In motorcycles that are connected together,
A power unit suspension system for a motorcycle, wherein the front lower part of the power unit is covered by a protection member extending from the vehicle body on the lower surface of the link. 2. The power unit suspension system for a motorcycle according to claim 1, wherein the protection member is a member that pivotally supports the link on the vehicle body side.