JP2001158391A - Motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To install an air cleaner of a large capacity in front of a rear cushion unit of a motorcycle, while reinforcing the frame of the motorcycle. SOLUTION: The vehicle body frame comprises a main pipe 5 extending backward from a head pipe 4 above an engine, seat pillar tubes 8 and 9 located at the rear end of the main pipe and pivotally supporting against their respective bottoms a rear arm 16 supporting the rear wheel, the rear cushion unit 19 suspending the rear arm vertically placed at the middle of the rear arm, and down tubes 6 and 7. A rear cushion bracket 20 projecting approximately horizontally and backward beyond the pivotally supported part 18 of the rear arm is connected to the rear end of the main pipe and a receiving part 20b to which the upper end of the unit 19 is connected is provided at the rear end of the bracket. The bracket 20 is supported by a reinforcing pipe from below, and backward extending seat rails 10 and 11 are welded at their respective front ends to the right and left side faces of the front of the bracket.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle, and more particularly, to a structure of a portion connected to an upper end portion of a rear cushion unit. An air cleaner is provided in front of the rear cushion unit while reinforcing a frame of the motorcycle. The space for installation can be secured, and thereby the intake efficiency of the engine can be improved.

[0002]

2. Description of the Related Art There is a motorcycle frame constructed by welding steel pipes to each other and connecting an upper end portion of a rear cushion unit to a main pipe extending rearward from a head pipe (for example, Japanese Patent Application No. 63-168969). No.). In this motorcycle frame, a connecting bracket is welded to a rear end of one main pipe extending straight backward from the head pipe and extending rearward, and a seat pillar tube or a seat is attached to the main pipe via the connecting bracket. The rail is connected, and the upper end of the rear cushion unit is pivotally supported by the connection bracket. And, since the rear cushion unit's axis is arranged on the extension of the main pipe so as to incline backward and downward so that the axis of the rear cushion unit is substantially along the axis of the main pipe, the vertical bending load applied to the main pipe during the cushion stroke is reduced. This results in increased frame stiffness.

[0003]

However, in the above-described conventional motorcycle frame, the rear cushion unit is moved forward and rearward during the cushion stroke because the main pipe and the rear cushion unit are positioned substantially on the same axis. The center of gravity of the rear cushion unit vibrates in the front-rear direction with the expansion and contraction, causing the center of gravity of the entire vehicle to vibrate in the front-rear direction. .
In order to solve such a problem, the rear cushion unit may be arranged in the vertical direction, and the vibration direction of the position of the center of gravity due to the expansion and contraction of the rear cushion unit may be set in the vertical direction. However, if the rear cushion unit is arranged vertically, the rear cushion unit will interfere with the engine or the lower end of the rear cushion unit will be located near the pivot axis of the rear arm, so the rear cushion unit can be mounted Will be gone.
On the other hand, in order to avoid the above problem, it is conceivable to extend the rear end of the main pipe rearward and connect the upper end of the rear cushion unit to the rear end. As the length becomes longer, the vertical bending load applied to the main pipe at the time of the cushion stroke increases, so that it becomes difficult to secure sufficient frame rigidity. In addition, when the rear cushion unit is arranged vertically, the installation space of the air cleaner is restricted, and as a result, the air cleaner must be arranged behind the rear cushion unit.
There is a problem in that the distance between the air cleaner and the carburetor is increased, and furthermore, the duct between the air cleaner and the carburetor cannot be linearly arranged, resulting in a decrease in the intake efficiency of the engine. Therefore, the present invention devises the structure of the body frame so that the space for arranging the air cleaner between the rear cushion unit and the engine can be secured while reinforcing the body frame with respect to the vertical arrangement of the rear cushion unit. That is the task.

[0004]

Means taken to solve the above-mentioned problems include one main pipe extending rearward from the steering head pipe above the engine,
A pair of left and right pivots extending obliquely downward and rearward from the rear end of the main pipe, and having a lower end supporting a rear wheel and pivotally supporting the front end of a rear arm extending rearward so as to swing vertically. A rear pillar unit, which is disposed vertically between the pivot portion of the rear arm and the rear wheel, and suspends the rear arm; and left and right down tubes extending downward from the head pipe. The vehicle body frame is constituted by the following (a) and (b) on the assumption that the motorcycle is provided with a vehicle body frame constituted by (B) A rear cushion bracket that projects substantially horizontally rearward from the pivot of the rear arm is connected to the rear end of the main pipe, and the rear end of the bracket is
A lower U-shaped receiving portion to which the upper end of the rear cushion unit is connected is provided, a lower portion of the rear cushion bracket is supported by a reinforcing pipe provided on the vehicle body frame, and a front portion of the rear cushion bracket is provided. The front end of the seat rail extending rearward is welded to both left and right side surfaces. (B) The rear end of the rear cushion bracket extends rearward from the welded portion with the front end of the seat rail.

[0005]

The lower portion of the rear cushion bracket is supported by a reinforcing pipe provided on the vehicle body frame.
Since the front ends of the seat rails extending rearward are welded and fixed to both left and right sides of the front portion of the rear cushion bracket, the seat rails are integrated with the main pipe, thereby reinforcing the body frame. Rigidity can be improved. The rear end of the rear cushion bracket extends rearward from the welded portion with the front end of the seat rail, and the rear cushion unit is connected to the extended rear end. A space for disposing the air cleaner is provided between the cushion unit and the engine, and the air cleaner can be disposed in this space. By arranging the air cleaner in this way, the distance between the air cleaner and the carburetor is shortened, and the duct connecting the air cleaner is straight, and the airflow resistance is significantly reduced. To be improved.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a side view of a motorcycle equipped with a frame according to the present invention, FIG. 2 is a side view of a motorcycle frame according to the present invention, FIG.
2 is a sectional view taken along line IV-IV in FIG. 2, and FIG.
FIG. 5 is a sectional view taken along line V. In these figures, reference numeral 1 denotes an off-road motorcycle, and reference numeral 2 denotes a frame of the motorcycle. As shown in FIG. 2, the frame 2 includes a head pipe 4 that supports the front fork 3 so as to be steerable, one main pipe 5 extending downward from the head pipe 4, and a head pipe 4. Left and right down tubes 6, 7 extending downward, left and right seat pillar tubes 8, 9 connected to the rear end of the main pipe 5,
Left and right seat rails 10, 11 extending rearward from the rear end of the main pipe 5, and left and right back stays 12,
13 and so on. The rear ends of the down tubes 6, 7 and the lower ends of the seat pillar tubes 8, 9 are connected via a rear arm bracket 14. The left and right down tubes 6, 7 are connected by a cross tube 2a, and the left and right rear arm brackets 14 are connected by a cross tube 2b. Each pipe member constituting the frame 2 is a pipe member having a circular cross section except that the main pipe 5 is formed in a rectangular cylindrical shape.

The engine 15 has a front portion supported by the down tubes 6 and 7 and a rear portion having seat pillar tubes 8 and 9.
The rear arm 16 is supported by the rear arm bracket 14 via a pivot shaft 18. A rear cushion unit 19 is interposed between the rear arm 16 and the frame 2. The left and right arm portions 16a of the rear arm 16 are
It is slightly bent at a portion connected to the rear cushion unit 19 and is formed in a U-shape so as to project downward when viewed from the side. The rear cushion unit 19 is mounted so that its axis is directed substantially vertically so as to be substantially parallel to the seat pillar tubes 8 and 9 of the frame 2 when viewed from the side. 5 is pivotally supported by a rear cushion bracket 20 welded to the rear end.

The rear cushion bracket 20 is formed by bending a plate material. A central portion in the longitudinal direction is formed in a substantially rectangular cylindrical shape with a dimension into which the main pipe 5 can be fitted. It is formed in a character shape. Note that a portion formed in the shape of a rectangular tube is denoted by reference numeral 20 in the figure.
A part indicated by a and a rear part formed in a downward U-shape in cross section is shown by a reference numeral 20b. As shown in FIG. 4, the rear cushion bracket 20 is welded to the main pipe 5 in a state where the rear end of the main pipe 5 is fitted into the rectangular tubular portion 20a. As shown in FIG. 5, the upper end of the rear cushion unit 19 is pivotally supported by a rear U-shaped portion 20b with a downward section in cross section.

Further, the rear cushion bracket 2
On the left and right sides of 0, seat pillar tubes 8, 9 and
Seat rails 10 and 11 are respectively welded. That is, the rear cushion bracket 2 is provided between each member connected to the rear end of the main pipe 5 and the main pipe 5.
0 will intervene. The seat rail 10
Is a seat rail extending horizontally rearward from the side surface of the bracket 20, while the other seat rail 11 is a connecting portion at the upper end of the rear cushion unit 19 and is a seat rail bent downward and extending rearward. Therefore, mounting and removing of the mounting bolt of the connecting portion at the upper end of the rear cushion unit 19 can be easily performed by utilizing the space above the lower bent portion of the seat rail 11. In addition, the rectangular cylindrical portion 2 of the rear cushion bracket 20
A pair of left and right tension pipes (reinforcement pipes) 21, 21 are welded to the lower surface of Oa. The tension pipe 21 is disposed between the left and right seat pillar tubes 8 and 9, and has a rear end welded to the lower surface of the rear cushion bracket 20 and a front end welded to the down tubes 6 and 7. The welding position between the tension pipe 21 and the down tubes 6 and 7 is
7, a portion substantially in front of the cylinder head of the engine 15 and a portion to which the cross tube 2a is connected. Reference numeral 22 denotes a reinforcing plate interposed between the tension pipe 21 and the main pipe 5, and reference numeral 23 denotes a reinforcing plate for reinforcing a welded portion between the front end of the tension pipe 21 and the down tubes 6, 7.

Reference numeral 24 denotes a carburetor of the engine 15, and 25 denotes an air cleaner. This air cleaner 25 is mounted on the frame 2
Seat pillar tubes 8 and 9 and seat rails 10 and 11
The air cleaner element 25 a is disposed in a portion surrounded by the back stays 12 and 13 and is located forward of the rear cushion unit 19. Therefore, in the frame 2 configured as described above, the main pipe 5, the left and right down tubes 6, 7 and the left and right tension pipes 21, 21 are positioned at the top of the triangular pyramid, and the rear arm 16 swings. The frame 2 from the rear cushion unit 19
Is distributed and transmitted from the rear cushion bracket 20 to each of the pipes.

Further, since the main part of the air cleaner 25 (the air cleaner element 25a) is located in front of the rear cushion unit 19, the duct part for guiding the intake air to the carburetor 24 can be formed linearly and shortly. For this reason, the intake resistance can be reduced as much as possible by arranging the intake system members continuously in a line.

[0012]

As described above, in the motorcycle according to the present invention, the lower portion of the rear cushion bracket is supported by the reinforcing pipe provided in the vehicle body frame, and the left and right sides of the front portion of the rear cushion bracket. When the front end of the seat rail extending rearward is welded and fixed, the seat rail is integrated with the main pipe and the body frame is reinforced, so that the rigidity of the body frame can be improved. Also, the rear end of the rear cushion bracket extends rearward from the welded portion with the front end of the seat rail, and the rear cushion unit is connected to the extended rear end. A space for arranging the air cleaner is secured between the cushion unit and the seat pillar tube, and the air cleaner can be arranged in this space.
By arranging the air cleaner in this way, the distance between the air cleaner and the carburetor is shortened, and the duct connecting the air cleaner is straight and the ventilation resistance is significantly reduced, so that the intake efficiency of the engine is greatly reduced. This produces a unique effect of being improved. More specifically, a rear cushion bracket is connected to the rear end of the main pipe so as to project substantially horizontally toward the rear of the rear arm pivot, and the rear end of the rear cushion unit is connected to the rear end of the rear cushion bracket. Is provided, a single rear cushion unit for suspending the rear arm is disposed substantially vertically between the pivot portion of the rear arm and the rear wheel. Therefore, the space between the engine and the rear cushion unit becomes large. Therefore, it is possible to arrange a large-capacity air cleaner in the space, and since the duct between the air cleaner and the vaporizer is short and straight, the ventilation resistance of the duct is significantly reduced. Is done.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle equipped with a frame according to the present invention.

FIG. 2 is a side view of the frame of the motorcycle according to the present invention.

FIG. 3 is a plan view of a frame of the motorcycle according to the present invention.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view taken along line VV in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Motorcycle 2 ... Frame 4 ... Head pipe 5 ... Main pipe 6, 7 ... Down tube 19 ... Rear cushion unit 20 ... Rear cushion bracket 21 ... Tension Pipe 24: Vaporizer 25: Air cleaner

Claims (1)

[Claims] 1. A main pipe extending rearward from an upper part of an engine from a steering head pipe, extending obliquely downward and rearward from a rear end of the main pipe, and supporting a rear wheel at a lower portion of the main pipe. A pair of left and right seat pillar tubes having a pivot portion for pivotally pivoting a front end portion of a rear arm extending in a vertical direction, and a vertical position between the pivot portion of the rear arm and the rear wheel. A motorcycle having a body frame composed of one rear cushion unit for suspending the rear arm and left and right down tubes extending downward from the head pipe; And a rear cushion bracket projecting substantially horizontally toward the rear of the pivot portion of the rear arm. A lower U-shaped receiving portion to which an upper end of the rear cushion unit is connected, and a lower portion of the rear cushion bracket is supported by a reinforcing pipe provided in the vehicle body frame. Motorcycle, wherein a front end of a seat rail extending rearward is welded to both left and right side surfaces of the portion, and a rear end of the rear cushion bracket is extended rearward from a welded portion with the front end of the seat rail. .