JPH05278666A - Rear wheel suspension device for motorcycle - Google Patents

Abstract

PURPOSE:To provide a space at the center of a vehicle to improve space efficiency and secure a space for positioning a leaf spring by positioning the leaf spring under an engine in the longitudinal direction and also positioning a rotary damper in the vicinity of a pivot part of a rear arm. CONSTITUTION:Two exhaust pipes 18 and 19 are laid out so that they pass through the underside of a crankcase 14 and also a large diameter part 18b of one exhaust pipe 18 is adjacent in the lateral direction of a vehicle to a small diameter part 19a of the other exhaust pipe 19 at the underside of the crankcase 14. In this case, a damper of rotary type 23 in which a damper piston is positioned rotatably in a damper case is used and positioned near a pivot shaft 22 of a rear arm 8. Also a strip shaped leaf spring 25 is used as a buffer spring for a rear wheel 7, located at the underside of an engine and faced in the longitudinal direction, and positioned so that at least the front end of the leaf spring is located between the small diameter part 10a of the other exhaust pipe 19 and the crankcase 14. Then the front end of the leaf spring is pivoted at the bottom of the crankcase 14.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In a motorcycle, a rear wheel suspension provided between a rear arm and a vehicle body frame is provided with a buffer spring for reducing a shock applied to a rear wheel from a road surface and a damper for suppressing irregular vertical vibration of the rear wheel. The device is installed. As this rear wheel suspension device, conventionally, 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 vehicle body frame is adopted. Recently, a structure has been adopted in which the above-mentioned shock absorber is one, the upper end of which is connected near the rear end of the tank rail extending from the head pipe, and the lower end is connected near the pivot portion of the rear arm directly or through a link mechanism. It is generally done (see, for example, JP-A-59-120585).

[0003]

However, in the above-mentioned conventional device, since the upper end of one vertically long shock absorber is connected to the rear end of the tank rail, the arrangement of parts located in the center of the vehicle is adopted. The above-mentioned buffer occupies the space, so that the layout of the intake system is restricted, the capacity of the air cleaner cannot be sufficiently secured, and it is difficult to secure a space for arranging other vehicle-mounted parts such as a battery. There is a problem of inefficiency.

On the other hand, the present inventors are currently investigating the use of a leaf spring in place of the coil spring and a rotary damper in place of the telescopic damper. If a structure is adopted in which the leaf springs are arranged below the engine in the front-rear direction, there is a concern that it may be difficult to secure a space for arrangement due to interference with the exhaust pipe arranged below the engine depending on the arrangement structure. To be done.

The present invention has been made in view of the above-mentioned conventional problems and problems when arranging the leaf springs, and it is possible to improve space efficiency and secure a space for arranging the leaf springs below the engine. It is intended to provide a rear wheel suspension system for a motorcycle.

[0006]

According to the present invention, two exhaust pipes pass under the crankcase, and a large diameter portion of one exhaust pipe and a small diameter portion of the other exhaust pipe are below the crankcase. A rear wheel suspension device that is used in a motorcycle arranged adjacent to each other in the vehicle width direction and has a buffer spring that absorbs a shock applied to the rear wheel from the road surface and a damper that suppresses irregular vertical vibration of the rear wheel. In the above, the damper is a rotary damper in which a damper piston is rotatably arranged in a damper case, and the damper is arranged in the vicinity of a pivot portion of the rear arm, and the buffer spring is used as a strip plate-shaped leaf spring in the lower part of the engine. The front end of the leaf spring of the vehicle body frame or the crankcase is arranged so that at least the front portion thereof is located between the small diameter portion of the other exhaust pipe and the crankcase. It is characterized in that the pivotally supported in parts.

[0007]

According to the rear wheel suspension system for a motorcycle according to the present invention, the conventional coil spring and telescopic damper are replaced with a leaf spring and a rotary damper, respectively, and the leaf spring is arranged below the engine in the front-rear direction. In addition, since the rotary damper is arranged near the pivot part of the rear arm, a space is created in the center of the vehicle where the conventional coil spring and the telescopic damper are arranged, and the space is used to install on-vehicle components such as an air cleaner and a battery. It is possible to arrange them, or to arrange the intake system in a straight line, and the space efficiency is improved accordingly.

Further, according to the present invention, the large diameter portion of one exhaust pipe and the small diameter portion of the other exhaust pipe are arranged so as to be adjacent to each other in the vehicle width direction below the crankcase, and the small diameter portion and the crank are arranged. Utilizing the point that a space is obtained between the exhaust pipe and the crankcase, at least the front part of the leaf spring is arranged in the space and the front end is pivotally supported by the body frame or the bottom part of the crankcase. The dead space between them can be effectively used, and the space for arranging the leaf springs can be secured while avoiding interference with the exhaust pipe.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 4 are views for explaining a rear wheel suspension system of a motorcycle according to an embodiment of the present invention. FIG. 1 is a sectional view taken along the line I-I of FIG. 3, and FIGS. Examples FIG. 1 is a front view, a left side view, and a plan view of a motorcycle.

In the figure, 1 is a motorcycle equipped with the device of this embodiment, and the motorcycle 1 has the following structure. A head pipe 3 of the vehicle body frame 2 pivotally supports a front fork 5 that pivotally supports a front wheel 4 to the left and right, and a rear arm bracket 6 pivotally pivots a rear arm 8 that pivotally supports a rear wheel 7 up and down. .. Further, the engine 10 is suspended and supported by the tank rail 9 and the rear arm bracket 6 of the vehicle body frame 2. In addition, 5a is a steering handle, 11
Is a fuel tank, 12 is a seat rail, and 13 is a backstay.

The engine 10 is a water-cooled two-cycle V
Type two-cylinder engine, which has upper and lower cylinder blocks 15a and 15b and upper and lower cylinder heads 16 at the front of a crankcase 14 integrated with a transmission case.
a, 16b to form a V bank, and the upper block and the like on the left side of the engine (the same applies to the rear side of the vehicle),
The structure is such that the lower block and other parts are laminated and fastened so that they are located on the right side of the engine.

An upper cylinder air cleaner 17a is arranged above the engine 10 so as to be surrounded by the bottom wall of the fuel tank 11, and a lower cylinder air cleaner 17b is arranged on the right side. .. These air cleaners 17a and 17b are connected to the intake port of the crankcase via carburetors 17d and 17e. The intake duct 17c of the lower cylinder air cleaner 17b is extended to the vicinity of the upper cylinder air cleaner 17a.

An upper exhaust device 18 is connected to the upper cylinder block 15a, and a lower exhaust device 19 is connected to the lower cylinder block 15b. These exhaust devices 18 and 19 include exhaust pipe portions 18a and 19a having small diameters connected to the respective cylinder blocks, and exhaust chamber portions 18b and 19b which successively have large diameters and gradually have small diameters. Chamber portion 18b,
Mufflers 18c and 19c connected to the small diameter portion at the rear end of 19b
It consists of and.

The upper exhaust device 18 is arranged so that the exhaust pipe portion 18a having a small diameter is located in front of the engine and the maximum diameter portion of the exhaust chamber portion 18b is located below the crankcase 14. On the other hand, the lower exhaust device 19 includes the exhaust pipe portion 19
a is located below the crankcase 14, and the exhaust chamber portion 19b is located to the right of the rear wheel 7. Therefore, below the crankcase 14, the large-diameter exhaust chamber portion 18b of the upper exhaust device 18 and the small-diameter exhaust pipe portion 19a of the lower exhaust device 19 are adjacent to each other in the vehicle width direction.

The rear arm 8 has a pivot portion 20 at the front end.
The left and right arm bodies 20 having a are connected by a cross member 21, and the pivot portion 20a is pivotally supported by a pivot shaft 22 inserted and fixed between the rear arm brackets 6 and 6.

A rear wheel suspension device 24 of the present embodiment is arranged from below the front part of the rear arm 8 to below the rear part of the crankcase 14. The rear wheel suspension device 24 includes a leaf spring 25 that reduces a shock applied to the rear wheel 7 from the road surface,
A rotary damper 23 that suppresses irregular vertical vibration of the rear wheel 7.
It has and.

The rotary damper 23 is used for the rear arm 8.
Is disposed between the left and right pivot parts 20a, 20a. The damper 23 is configured such that a wing-shaped damper piston 23b is rotatably accommodated in a damper case 23a so as to define two chambers inside the case 23a. The damper case 23a is fixed to the upper and lower cross types of the rear arm bracket 6, and the damper piston 23b is connected to the rear arm 8 via a drive pipe 23c coaxial with the pivot shaft 22. Thereby, the damper piston 23b is configured to swing up and down together with the rear arm 8. The damper case may be fixed to the rear arm and the damper piston may be fixed to the pivot shaft.

The leaf spring 25 is made of a resin strip and is arranged below the front portion of the rear arm 8 in the vehicle front-rear direction and at the right side of the vehicle (FIG. 4).
reference). The rear end of the leaf spring 25 is pivotally supported on the lower surface of the cross member 21 of the rear arm 8. The front half portion of the leaf spring 25 is located between the bottom surface of the crankcase 14 and the exhaust pipe portion 19a of the lower exhaust device 19, and the support bracket portion 25a formed at the front end portion of the leaf spring 25 serves as a crank. A support bolt 26 is pivotally supported on a support boss portion 14 a provided on the bottom of the case 14. The rear end of the leaf spring 25 may be connected to the cross member 21 via a link.

The cross member 6a connecting the lower ends of the left and right rear arm brackets 6 is provided with front and rear pillows 27 and 28 which serve as fulcrums for deforming the leaf spring 25 as the rear arm 8 moves up and down. Each is installed. The pillows 27 and 28 are made of a relatively hard elastic material such as rubber or urethane foam.

The front pillow 27 is dimensioned and mounted so that the front pillow 27 contacts the upper surface of the leaf spring 25 even when the rear arm 8 is at the lowest position. On the other hand, the rear pillow 28 is dimensioned and attached so that it comes into contact with the leaf spring 25 when the rear arm 8 is lifted by a predetermined amount.

Next, the function and effect of this embodiment will be described. In the apparatus of this embodiment, when the rear wheel 7 rides on, for example, a convex portion of the road surface, the rear arm 8 is lifted by the impact force, and the rear end portion of the leaf spring 25 is pulled up accordingly, and the leaf spring 25 is pulled up.
Bends around the front pillow 27 as a fulcrum, and the impact force is alleviated according to the spring constant of the leaf spring 25 in this bending direction. Further, when the rear arm 8 further rises, the leaf spring 25 is further bent around the rear pillow 28 as a fulcrum, whereby the spring constant increases and the spring characteristic rises, so that a so-called progressive effect is obtained.

Further, as the rear arm 8 moves up and down, the damper piston in the damper 23 swings up and down, whereby the working oil in one chamber of the damper 23 passes through the throttle mechanism of the oil passage and enters the other chamber. A damping force is generated when flowing in, and irregular vertical vibration of the rear wheel 7 is suppressed.

According to the motorcycle 1 of this embodiment which performs such an operation, the buffer spring is changed from the conventional coil spring to the strip-shaped plate spring 25, and the plate spring 25 is arranged below the engine in the front-rear direction. Since the damper is changed from the conventional telescopic type to the rotary type damper 23 and the damper 23 is arranged rearward between the pivot parts 20a, 20a of the rear arm 8, the conventional coil spring and the like are arranged. A space is created in the center of the vehicle. Therefore, it is possible to arrange in-vehicle parts such as a battery using the space, and if necessary, it is also possible to arrange the intake system consisting of an air cleaner and a carburetor in a straight line in the space, which improves space efficiency. To be done.

In the apparatus of this embodiment, when the leaf spring 25 is arranged below the engine, the upper side exhaust device 18 is used.
By utilizing the fact that the large-diameter exhaust chamber portion 18b and the small-diameter exhaust pipe portion 19a of the lower exhaust device 19 are adjacent to each other below the crankcase 14, the exhaust pipe portion 19a and the crankcase 14 are connected to each other. The front portion of the leaf spring 25 was positioned in the space between them, and the front end of the leaf spring 25 was pivotally supported by the support boss portion 14a of the crankcase 14. As a result, a space for disposing the leaf spring can be secured below the crankcase while avoiding interference with the exhaust pipe.

Further, in this embodiment, the lower part and the left part of the leaf spring 25 are surrounded by the exhaust pipe, so that it is possible to suppress the stepping stones or the like from hitting the leaf spring 25 and to extend the life of the leaf spring 25.

[0026]

As described above, according to the rear wheel suspension system for a motorcycle according to the present invention, since the leaf spring and the rotary damper are adopted, a space can be obtained at the center of the vehicle body, so that the space efficiency can be improved. Utilizing the fact that the small diameter portion and the large diameter portion of the exhaust pipe are adjacent to each other below the crankcase is effective, and at least the front portion of the leaf spring is positioned between the small diameter portion and the crankcase bottom surface. Since the front end of the leaf spring is pivotally supported by the body frame or the bottom portion of the crankcase, there is an effect that a space for arranging the leaf spring can be secured below the crankcase while avoiding interference with the exhaust pipe.

[Brief description of drawings]

1 is a view showing a front end support portion of a leaf spring of a rear wheel suspension system of a motorcycle according to an embodiment of the present invention, and FIG.
2 is a cross-sectional view taken along line I-I of FIG.

FIG. 2 is a front view of the motorcycle.

FIG. 3 is a left side view of the motorcycle.

FIG. 4 is a plan view of the motorcycle.

[Explanation of symbols]

1 Motorcycle 7 Rear Wheel 8 Rear Arm 14 Crankcase 14a Support Boss (Crankcase Bottom) 18, 19 Upper and Lower Exhaust Device (Exhaust Pipe) 18b Exhaust Chamber Part (Large Diameter Part of One Exhaust Pipe) 19a Exhaust Pipe part (small diameter part of the other exhaust pipe) 20a Pivot part 23 Damper 24 Rear wheel suspension device 25 Leaf spring 25a Support bracket part (front end of leaf spring)

Claims (1)

[Claims] 1. The two exhaust pipes pass below the crankcase, and the large diameter portion of one exhaust pipe and the small diameter portion of the other exhaust pipe are adjacent to each other in the vehicle width direction below the crankcase. In a rear wheel suspension device that is used in a motorcycle that has been installed, and that includes a buffer spring that cushions a shock applied to the rear wheel from the road surface and a damper that suppresses irregular vertical vibration of the rear wheel, the damper is provided in a damper case. The damper piston is rotatably arranged in the rear arm and is arranged near the pivot part of the rear arm. The front portion is disposed so as to be located between the small diameter portion of the other exhaust pipe and the crankcase, and the front end portion of the leaf spring is pivotally supported by the vehicle body frame or the bottom portion of the crankcase. Rear wheel suspension system for motorcycles.