JP3249563B2 - Buffer spring arrangement structure for rear wheel suspension system for motorcycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel suspension system for a motorcycle, and more particularly, to an improvement in the arrangement of a leaf spring when a leaf spring is employed as a buffer spring.

[0002]

2. Description of the Related Art Conventionally, a rear wheel suspension system for a motorcycle employs a structure in which a shock absorber composed of a coil spring and a telescopic tubular damper is interposed between a rear arm and a body frame. And recently, the above-mentioned shock absorber is one,
In general, this is disposed directly or via a link mechanism between the vicinity of the pivot portion of the rear arm and the lower portion of the fuel tank of the vehicle body frame or the lower portion of the seat (see, for example, Japanese Unexamined Patent Application Publication No. -120585).

However, in the above-mentioned conventional apparatus, the space for arranging the parts located in the center of the vehicle is occupied by the shock absorber, which makes it difficult to secure a space for arranging other in-vehicle parts such as an air cleaner and a battery. There is a problem that space efficiency is poor.

[0004]

On the other hand, the present inventors are currently studying the use of a leaf spring instead of the coil spring. However, even if a leaf spring is used, the space efficiency is not so much improved depending on the arrangement structure, or the space efficiency can be improved, but the maintainability of the leaf spring is reduced, or the leaf spring is stepped off a road surface or the like. There are concerns about various problems, such as easy damage.

[0005] The present invention has been made in view of the above-mentioned problems of the conventional structure and the problem of employing a leaf spring.
An object of the present invention is to provide a buffer spring arrangement structure of a rear wheel suspension device for a motorcycle that can improve space efficiency, secure maintainability, and suppress damage caused by flying stones and the like.

[0006]

SUMMARY OF THE INVENTION The present invention comprises a shock absorbing spring for alleviating a shock applied to a rear wheel from a road surface, and a damper for suppressing irregular vertical vibration of the rear wheel. In the arrangement of the buffer spring of the motorcycle rear wheel suspension device interposed in the vehicle, the buffer spring is a resin leaf spring, and the leaf spring is directed downward in the vehicle front-rear direction below the engine, and The plate spring is arranged to be offset from the line on the side opposite to the side stand, and the leaf spring is a long strip-shaped plate extending from below the front part of the crankcase of the engine to below the front part of the rear arm. The front end of the leaf spring is connected to the vehicle body side, the rear end is connected to the front side of the rear arm, and the contact between the leaf spring and the leaf spring is changed as the rear arm is raised. Flexed spring That the fulcrum is disposed in the longitudinal direction midway portion of the leaf spring, together to face the road surface without being also covered with the engine lower part of the plate spring and the exhaust pipe anything,
When viewed from the side of the vehicle, at least a front half of the leaf spring is overlapped with the exhaust pipe.

[0007]

According to the buffer spring arrangement structure of the rear wheel suspension device according to the present invention, the fulcrum for bending the leaf spring while changing the contact point with the leaf spring as the rear arm is raised is moved in the longitudinal direction of the leaf spring. Since the spring is disposed in the middle part, the spring characteristic can be changed to a so-called progressive characteristic in which the spring constant increases in a quadratic curve as the rear arm rises, while avoiding a concentrated load from acting on the leaf spring. In addition, the leaf spring and the lower portion of the exhaust pipe are opposed to the road surface without being covered with anything, and at least the front portion thereof is arranged so as to overlap with the exhaust pipe when viewed from the side of the vehicle. The dead space, which has been rarely used in the past, between the right and left exhaust pipes can be effectively used, so that the space efficiency can be improved, and maintainability and cooling performance can be secured.

Further, since the leaf spring is disposed below the engine, the leaf spring can be directly handled from below the engine, so that maintenance work such as attaching and detaching the leaf spring or adjusting the initial load can be ensured.

Further, since the leaf spring is disposed below the engine and wraps with the exhaust pipe, the exhaust pipe functions as a protection member against, for example, flying stones from the road surface, and damage to the leaf spring can be suppressed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 5 are views for explaining a leaf spring arrangement structure of a motorcycle rear wheel suspension device according to one embodiment of the present invention. FIG. 1 is a side view, FIG. 2 is a plan view, FIG. 4 is a cross-sectional development view of a link mechanism, and FIG. 5 is a side view of a motorcycle employing the suspension device.

In FIG. 1, reference numeral 1 denotes a motorcycle employing the apparatus of the embodiment. Body frame 2 of the motorcycle 1
Is a so-called double cradle type, in which the front ends of a pair of left and right diagonally downwardly extending tank rails 4, 4 are connected to the head pipe 3, and a rear arm bracket 5 is connected to the rear ends of the tank rails 4, 4. And the lower end of each rear arm bracket 5 and the head pipe 3 are connected by a pair of left and right down tubes 6, 6. The left and right rear arm brackets 5, 5 are connected by an upper cross pipe 5b and a lower cross pipe 5c. Reference numeral 7 denotes a reinforcing tension pipe for connecting the tank rail 4 to the down tube 6, reference numeral 8 denotes a seat rail, and reference numeral 9 denotes a back stay for supporting a rear end of the seat rail 8.

A fuel tank 10 is provided on a tank rail 4 of the vehicle body frame 2, an air cleaner 10a is provided inside the tank 10, a seat 11 is provided on a seat rail 8, and a tank rail 4, a rear arm bracket 5, The engine 12 is mounted in the cradle constituted by the down tube 6. In addition, 10b is a battery.

The engine 12 is of an air-cooled 4-cycle parallel 4-cylinder type. A cylinder block 14 and a cylinder head 15 are stacked in a forwardly inclined state at the front of a crankcase 13 integrated with a transmission case. The head cover 16 is put on the upper mating surface of the cylinder head 15. 28 is the crankcase 1
3 is an oil pan attached to the bottom surface.

In the engine 12, the front boss 13a of the crankcase 13 is bolted and fixed to a front bracket 6a fixed to the down tube 6, and the rear boss 13b is fixed to the rear arm bracket 5. It is mounted and fixed to the vehicle body frame 2 by being bolted and fixed to the rear suspension pipe 5d.

Each exhaust port opening to the front wall of the cylinder head 15 has four exhaust pipes 18a-
18d is connected. Of the exhaust pipes, the exhaust pipes 18a and 18d at the left and right ends are arranged on the left side of the vehicle, and the two central exhaust pipes 18b and 18c are arranged on the right side of the vehicle and pass under the oil pan 28, respectively. And are connected to the left and right merging pipes 19a, 19b, respectively.

Here, the left exhaust pipes 18a, 18
(d) The merging pipe 19a is arranged so as to be deviated in the vehicle width direction toward the vehicle center line A side as compared with the right exhaust pipe or the like because it is necessary to secure a space for disposing the side stand 55 on the left side of the vehicle. Have been.

The left and right merging pipes 19a, 19b extend to the left and right near the rear end of the oil pan 28. The left and right silencers 20a are provided at each of the laterally expanded ends.
20b are connected to each other, and the silencers 20a,
Reference numeral 20b extends obliquely upward on the left and right sides of the rear arm 21 described in detail below.

The rear arm 21 includes a pair of left and right rectangular cylindrical arm bodies 22a and 22b, each having a front end portion formed by a circular cylindrical pivot pipe 23, and a portion rearward of the pipe 23 formed by a rectangular cylindrical cross body. The rear wheel 26 is rotatably supported by an axle 25 fixedly inserted between the rear ends of the left and right arm bodies 22a and 22b. The pivot pipe 23 is supported by a pivot shaft 27 inserted therethrough via a bearing 23a, and the pivot shaft 27 is fixedly fastened to the left and right rear arm brackets 5 with nuts 27a.

A rear wheel suspension device 29 is provided from below the front portion of the rear arm 21 to below the engine. The rear wheel suspension device 29 is disposed between the rear arm 21 and the rear arm bracket 5 to suppress irregular vertical vibration of the rear wheel 26, and a bottom surface of the rear arm 21 and the engine 12 And a link mechanism 56 connecting the leaf spring 31, the damper 30, and the rear arm 21 to alleviate the shock applied to the rear wheel 26 from the road surface.

The rotary damper 30 includes a case body 32
a and a lid 32b, a substantially plate-shaped wing-shaped piston 33 that defines the interior of the case into two chambers is housed and arranged in a substantially fan-shaped damper case 32 in side view, and an upper end 33 of the piston 33 is provided.
The drive shaft 34 is inserted into the drive shaft 34a and spline-fitted, and the drive shaft 34 is rotatably supported by the damper case 32. In addition, in the lid 32b,
A plurality of passages 32c for communicating the two chambers defined by the airfoil piston 33 are formed, and a throttle mechanism (not shown) is provided in the passage 32c. When the airfoil piston 33 is swung by the drive shaft 34, the hydraulic oil moves from one chamber to the other chamber through the throttle mechanism, thereby generating a damping force.

Here, the drive shaft 34 of the damper 30 is located between the pivot pipe 23 and the cross member 24 and is oriented in the vehicle width direction.
Numeral 2 is vertically elongated from the drive shaft 34. The center line B of the damper 30 is deviated from the vehicle center line A to the right side of the vehicle by a dimension a.

Upper and lower bosses 32d and 32e are formed integrally with the case body 32a of the damper 30.
The two bosses 32d, 32e are fixed with bolts 35a, 35b.
To the support bracket 36. The support bracket 36 is shaped like a letter F when viewed from the side.
a and 36b are welded and fixed to the rear suspension pipe 5d and the lower cross pipe 5c, respectively.

The link mechanism 56 includes a damper arm 37 for driving the damper 30, an intermediate link 38 for connecting the arm 37 and the rear arm 21, and a left and right link for connecting the intermediate link 38 and the leaf spring 31. And a pair of right spring arms 39. Above damper arm 37
Is spline-fitted to the outwardly protruding end of the drive shaft 34, and is fixedly fastened with a nut. The damper arm 37 extends near the lower part of the cross pipe 24, and its lower end 37 b is connected to the lower end 38 a of the intermediate link 38 by the upper end 3 of the pair of left and right spring arms 39.
9a. The connecting portions are provided between the left and right spring arms 39 and outwardly, respectively, with collars 39c, 3c.
9d, the connecting bolt 40a is inserted, and the nut 4
0b, the intermediate link 38 is connected to the collar 39c, and the damper arm 37 is connected to the collar 39d via a needle bearing.

The intermediate link 38 is connected to the rear arm 21 by connecting the upper end 38b of the intermediate link 38 to a U-shaped support bracket 24a welded and fixed to the lower surface of the cross member 24 with support bolts 41a and nuts 41b. Are linked.

The lower end 39b of the spring arm 39
A rear spring bracket 43 via a rubber bush 42
Are fixed with bolts and nuts 44a and 44b. The rubber bush 42 is formed by inserting a rubber ring 42c between the inner pipe 42a and the outer pipe 42b and fixing the outer ring 42c by baking. I have.

As shown in FIG. 4, the support portion 43b of the rear spring bracket 43 is deviated to the right from the vehicle center line A by a dimension b. The rear end portion 31a of the leaf spring 31 is fixed on the support portion 43b by a pressing plate 43c and a fixing bolt 45.
Also deviates to the right from the vehicle center line A by the dimension b (see FIG. 3). The leaf spring 31 is connected to the oil pan 28.
Is formed of a band-shaped resin extending in the front-rear direction of the vehicle, and gradually becomes thinner from the center toward the front and rear ends.

The exhaust pipes 18a and 18d and the left junction pipe 19a are located on the left side of the leaf spring 31, and the exhaust pipes 18b and 18c and the right junction pipe 19b are located on the right side. The front half of the leaf spring 31 overlaps the exhaust pipes 18a to 18d when viewed from the side of the vehicle. The upper surface and the left and right side surfaces of the leaf spring 31 are covered with a heat insulating film 46 to block heat from the exhaust pipe and the like.

The front end 31b of the leaf spring 31 has a support portion 47b having the same width as the leaf spring 31 of the front spring bracket 47.
Are fixed by a support plate 48a and a bolt 48b having the same width.
Is supported by a support boss 13c formed at the front end of the bottom surface of the crankcase 13 by a support bolt 49a so as to be swingable. The front end 31b and the rear end 31a of the leaf spring 31 are sandwiched by brackets 47 and 43, respectively, with a pair of upper and lower rubber plates interposed therebetween. The rubber plate is used to relieve stress when a resin leaf spring is tightened by the metal bracket.

Further, an adjustment lever 50 for adjusting the initial load of the leaf spring 31 is disposed above the substantially center of the leaf spring 31 in the longitudinal direction. This adjustment lever 5
Reference numeral 0 denotes a metal plate having a lower surface formed in an arc shape, and a rubber sheet 51 is attached to the lower surface. Since the lower surface of the adjusting lever 50 has an arc shape, the leaf spring 31
The contact point changes with the vibration of the rear arm 21 so that the spring characteristics can be made progressive and the concentrated load can be prevented from acting on the spring. A support boss 50a formed at the front end of the adjusting lever 50 is supported via a support shaft 52 by a support boss 28a integrally formed on the lower surface of the oil pan 28. An adjusting bolt 53 is screwed into the center of the adjusting lever 50, and the head of the adjusting bolt 53 is in contact with an adjusting seat surface 28 b formed integrally with the oil pan 28. In addition, 53a is a lock nut.

A bump stopper 54 for restricting the amount of deformation of the leaf spring 31 is provided above the rear part of the leaf spring 31. The stopper 53 is in the form of a rubber block and is bolted and fixed to a mounting boss 32f integrally formed on the bottom surface of the damper case 32.

Next, the operation and effect of this embodiment will be described. In the present embodiment, when the rear wheel 26 rides on, for example, a convex portion of the road surface, the rear arm 21 is raised by the impact force, and accordingly, the rear end 31 a of the leaf spring 31 is moved via the intermediate link 38 and the spring arm 39. The leaf spring 31 is bent with the adjustment lever 50 as a fulcrum, and the impact force is reduced by the spring force at this time. In addition, the wing-shaped piston 33 in the damper 30 rotates as the rear arm 21 is raised and lowered, and the hydraulic oil in each chamber passes through the throttle mechanism of the oil passage 32c, thereby generating a damping force. In this case, since the drive shaft 34 of the damper 30 is located closer to the intermediate link 38 than the pivot shaft 27, the swing angle θ of the damper arm 37 is smaller than the swing angle θ1 of the rear arm.
2 is larger.

In the rear wheel suspension device performing such an operation, a leaf spring 31 is employed as a buffer spring.
Is disposed below the engine 12 in the vehicle front-rear direction and the front portion thereof is overlapped with the exhaust pipes 18a to 18d when viewed from the side of the vehicle. The dead space that has not been used can be effectively used, and the space efficiency can be improved.

Further, since the leaf spring 31 is disposed below the engine 12, the leaf spring 31 is exposed toward the lower side of the engine. Therefore, the leaf spring 31 can be directly operated from below the engine. It is possible to ensure the maintainability in the work of attaching and detaching the spring 31 or the work of adjusting the initial load.

Further, the leaf spring 31 is connected to the lower part of the engine 12 and the left exhaust pipes 18a, 18d.
b, 18c, the exhaust pipes 18a-18
For example, d functions as a protection member against flying stones from the road surface, and damage to the leaf spring 31 can be suppressed. Further, it is possible to prevent the leaf spring 31 from contacting the road surface during banking, and in this respect, it is possible to prevent the leaf spring 31 from being damaged.

Further, since the heat insulating film 46 is formed on the upper and side surfaces of the leaf spring 31, heat from the exhaust pipes 18a to 18d can be cut off. Can be arranged without any trouble.

In this embodiment, since the rotation center of the damper 30 is set closer to the pivot of the intermediate link 38 than the pivot shaft 27, the swing angle θ2 of the damper arm 37, that is, the swing angle of the piston valve 33 is reduced. The swing angle becomes larger than the swing angle θ1 of the rear arm 21. As a result, the degree of freedom in setting the damping characteristic of the damper 30 can be increased.

In the above embodiment, the exhaust pipe is shown on the left and right sides of the leaf spring 31. However, in the present invention, the exhaust pipe may be arranged only on one side of the leaf spring. It can be applied to the case.

[0038]

As described above, according to the buffer spring arrangement of the rear wheel suspension system of the motorcycle according to the present invention, the leaf springs are arranged in the front-rear direction below the engine, and the leaf springs are raised as the rear arm rises. Since the fulcrum for bending the leaf spring while changing the contact point with the spring is disposed at an intermediate portion in the longitudinal direction of the leaf spring, it is possible to prevent the concentrated load from acting on the leaf spring and to reduce the spring characteristic to a so-called progressive characteristic. There is an effect that can be. In addition, the leaf spring and the lower portion of the exhaust pipe below the engine are opposed to the road surface without being covered with anything, and at least the first half of the leaf spring is arranged so as to wrap with the exhaust pipe when viewed from the side of the vehicle. In addition, there is an effect that the cooling can be ensured, and that the leaf spring can be protected from flying stones, road surface contact and the like by the exhaust pipe.

[Brief description of the drawings]

FIG. 1 is a side view showing a leaf spring arrangement structure of a motorcycle rear wheel suspension device according to an embodiment of the present invention.

FIG. 2 is a plan view of the structure of the embodiment.

FIG. 3 is an expanded sectional view of the structure of the embodiment.

FIG. 4 is an exploded cross-sectional view of a link portion of a link and an arm in the structure of the embodiment.

FIG. 5 is a side view of a motorcycle having the structure of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motorcycle 12 Engine 18a-18d Exhaust pipe 21 Rear arm 26 Rear wheel 29 Rear wheel suspension device 30 Damper 31 Leaf spring

Claims (1)

(57) [Claims] 1. A motorcycle provided with a buffer spring for reducing shock applied to a rear wheel from a road surface and a damper for suppressing irregular vertical vibration of the rear wheel, the motorcycle being interposed between a rear arm and a vehicle body fixing portion. in the arrangement structure of the buffer spring of the rear wheel suspension device, toward the buffer spring resin plate Banetoshi, in the vehicle longitudinal direction plate spring by the engine downward, and the vehicle
The leaf spring is arranged to be offset from the center line to the side stand side, and the leaf spring is a long strip-shaped plate extending from below the front part of the crankcase of the engine to below the front part of the rear arm. The front end of the leaf spring is connected to the vehicle body side, the rear end is connected to the front side of the rear arm, and the contact point with the leaf spring is changed as the rear arm rises. A fulcrum for bending the leaf spring is provided at an intermediate portion in the longitudinal direction of the leaf spring, so that the leaf spring and the exhaust pipe below the engine are not covered with anything.
Ku causes face the road surface, buffer spring arrangement of wheel suspension after a motorcycle as viewed from the side of the vehicle, characterized in that was wrapped with the exhaust pipe at least half portion of the plate spring.