JPS6021113B2 - Chain-driven motorcycle with diamond frame - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chain-driven motorcycle equipped with a diamond frame, and particularly to an engine mount structure thereof.

The rear arm that pivotally supports the rear wheel is pivoted to the frame so that it can swing freely, but the pivot portion of the rear arm in the frame is subject to load changes as the rear arm swings, so it is not suitable for large machines. Objective strength is required.

In particular, in so-called monochrome suspension type motorcycles in which a suspension device is bridged between the upper part of the rear arm and the upper front part of the frame, the knee suspension device extends in the front-rear direction above the engine. Not only a vertical load but also a longitudinal force is applied to the pivot. Therefore, if the frame itself were to receive the load from the rear arm, the mounting structure would become complicated and large due to the concentrated load. On the other hand, a so-called diamond-shaped frame uses part of the engine as a frame structure by dividing the frame in front and behind the engine crankcase, and by spanning the front and rear parts of the crankcase between the divided frames. In this case, since the connection position at the rear of the crankcase and the pivot point of the rear arm are very close to each other, the structure of this part becomes complicated and requires even greater rigidity and mechanical strength.

Furthermore, in this case, if a chain is used as the drive method for the rear wheels, the drive splot on the engine side, around which the chain is wound, is located on one side of the rear part of the crankcase, so this drive splot connects with the rear part of the crankcase. The position and the pivot point of the rear arm are extremely close together.

Then, especially when the chain is strongly stretched due to rapid acceleration or deceleration, the reaction force of the chain will be transmitted to the crankcase via the drive splot. Therefore, while the vehicle is running, the crankcase receives both the impact force from the rear arm transmitted through the frame and the reaction force of the chain, which further increases the load burden.

For this reason, there is a risk that the engine may be twisted or a large bending moment may be applied to the attachment portion to the frame, so sufficient consideration must be given to the load. This invention was made based on the above circumstances, and it is possible to distribute the load transmitted from the rear arm to the crankcase during driving and the load associated with the reaction force of the chain over the entire frame, thereby preventing engine twisting and load concentration. Another object of the present invention is to provide a chain-driven motorcycle equipped with a diamond frame that simplifies the vicinity of the point where the rear part of the crankcase is connected to the frame.

That is, in order to achieve the above object, the present invention pivots the front end of the rear arm to the rear part of the crankcase so as to be able to swing freely, and connects the front end of the crankcase to the frame on a substantially extended line passing through the pivot point of the rear arm. It is characterized by providing a mounting portion and a drive side chain sprocket around which the chain is wound.

An embodiment of the present invention will be described below with reference to the drawings.

In the figure, 1 is a steering head pipe, and one main pipe 2 and one down tube 3 are each welded to the rear surface of the steering head pipe.

In addition, these main pipe 2 and down tube 3 are
They are connected and reinforced by a gusset 4 and an auxiliary pipe 5. A pair of left and right seat pillar tubes 6, 6 are welded to the main pipe 2, and seat rails 7, 7 are welded to the seat pillar tubes 6, 6. Backstays 8, 8 are spanned between the rails 7, 7 midway. Note that cross members 9 are bridged between each pair of seat pillar tubes 6, 6 and between seat rails 7, 7. Such a structure constitutes a pipe frame 10, and a rear arm 11 is installed at the rear of this frame 10.
is placed. The rear arm 11 has a pair of left and right rear forks 12, 12, and auxiliary pipes 13, 13 and 14, 1.
4 to form a substantially triangular frame on the side, and a rear wheel 15 is pivotally supported at the rear end. The lower front end of the rear arm 11 is pivotally supported on the frame 10 by a pivot shaft 40 together with the engine, which will be described later. Further, the upper part of the front end of the rear arm 11 forms a connecting portion between the auxiliary pipes 13, 13, and a U-shaped bracket 16 is welded to this connecting portion. A suspension device 17 is installed between the bracket 16 and the main pipe 2. That is, the main pipe 2 is extended to a portion covered by a fuel tank (not shown), and another bracket 18 is welded to the rear end of the main pipe 2. A shock absorber 1 as a suspension device 17 is provided between the bracket 16 and this bracket 18.
9 are connected via pivot shafts 20 and 21, and a coil spring 22 that biases the shock absorber 19 in the expansion direction is spanned between the cylinder and the piston rod of the shock absorber 19. As a result, the suspension system 17 extends in the longitudinal direction along approximately the center line of the vehicle body, and a portion of the suspension system 17 passes through the approximately triangular space 23 surrounded by the seat pillar tube 6, seat rail 7, and backstay 8. ing. Thus, the engine 25 is mounted on the frame 10 having the above configuration.

The engine 25 is, for example, a four-stroke engine,
It is constructed by connecting a cylinder 27 and a cylinder head 28 on a crankcase (gear case) 26, and the crankcase 26 is divided into left and right parts. In addition, 29
is a carburetor connected to the rear surface of the cylinder 27, and an intake silencer (not shown) is connected to the rear of the carburetor. The front end of the crankcase 26 is connected to the lower end of the down tube 3 via a bracket 30.

In this case, as is clear from FIG. 1, the bracket 30 is such that the rear fork 12 of the rear arm 11 is
It is provided on each extension of the lines x, 1 x, and 0 that pass through 0.
These three brackets are each fastened to the down tube 3 and the crankcase 26 at a plurality of locations via bolts 31, 32, . . . . Further, the cylinder head 28 is fastened to the seat pillar tubes 6, 6 with bolts 34 via another bracket 33, and is supported by another bolt 35. Furthermore, this crankcase 26 has a seat pillar tube 6,
6. In this case, the crankcase 26 is fixed at two locations at the rear end, one of which is secured by passing bolts 38 through brackets 37, 37 (only one shown) provided on the seat pillar tubes 6, 6 and tightening the crankcase 26. ing. Moreover, the other is a pivot shaft 40,
This will be explained below with reference to FIG. That is, 41, 41 are brackets welded to the seat pillar tubes 6, 6, and the pivot shaft 40 is spanned between these brackets 41, 41, and is tightened with a nut 42. The four pivot shafts pass through a bracket portion 43 formed at the rear end of the crankcase 26 of the engine. Note that since the crankcase 26 is divided into left and right parts, the bracket part 43 is also divided, and the pivot shaft 40 passes through these divided bracket parts 43a and 43b while abutting each other. . Curlers 44, 44 are attached to both sides of the pivot shaft 40 on the left and right sides of the bracket portion 43, and these curlers 44,
Pivot tube bodies 46, 46 welded to the front ends of the rear oaks 12, 12 are rotatably attached to the outer periphery of the shaft 44 via bearing metals 45 having dovetail-shaped grooves on the inner peripheral surface. has been done. Therefore, such a pivot shaft 40 connects the rear arm 11 to the crankcase 26, and also connects the rear end of the crankcase 26 to the frame 01. As a result, the front and rear ends and upper part of the engine 25 are connected to the frame 10, and the engine constitutes a part of the frame, forming a so-called diamond frame. Note that 47 is an oil seal, 48 is a pad inserted into the crankcase 26, 49 is a patch, 50 is a chain guide mill, and 54 is a kick arm. Further, 51 is a driving side chain sprocket provided on the crankcase 26, and a chain 53 is spanned between it and a driven side sprocket 52 provided on the rear wheel 15.

As is clear from FIG. 1, the drive-side chain sprocket 51 is also provided substantially on the extension of the lines x and 1x, through which the rear fork 12 passes through the pivot shaft 40. Note that the lower surface of the crankcase 26 is covered by an engine garbo, and the crankcase 26 is protected from road surfaces, stones, etc.
It is designed to protect from mud. engine guard 55
The front end of the bracket 30' is fastened with a bolt 56, and the rear end is fastened with a bolt 57 to the cross member 9. And this engine guard 55 is the engine 2
5 is attached to the frame 0', and does not have enough mechanical strength to function as a substantial frame structure. According to this configuration, the front end of the rear arm 11 is directly pivotally supported via the pivot shaft 40 to the crankcase 26 of the engine 25, which constitutes a part of the frame 10.
The loads generated in the vertical and horizontal directions as the rear arm 11 swings are borne by the crankcase 26, which is inherently rigid. Therefore, the pivoting of the rear arm 11 is performed reliably, and there is no possibility that the pivoting portion will be deformed even if there is an unbalanced load. Moreover, the front part of the crankcase 26 is connected to the line x, 1 x passing through the pivot point 40 of the rear arm 11. Since it is connected to the down tube 3 on the extension of the monochrome suspension, even if a load is transmitted to the crankcase 26 not only in the vertical direction but also in the longitudinal direction due to the effect of the monochrome suspension, this load is not twisted or twisted to the crankcase 26. It can be transmitted to the down tube 3 without generating a moment.

In addition, the drive side chain sprocket 51 also follows the above line
Since it is provided on the extension of
Even when the load is applied to the down tube 3, this load can be transmitted to the down tube 3 without causing twisting or bending moment in the crankcase 26. Therefore, the unevenness of the load applied to the crankcase 26 can be suppressed.
There is an advantage that the support rigidity of the engine 25 is increased, and there is no possibility that the engine 25 will swing undesirably. In addition, at the rear of the crankcase 26, the rear arm 11 is pivotally supported by the crankcase 26 itself, so the rear arm 11 is supported by the frame 10, that is, the seat pillar tubes 6, 6.
There is no need for a special structure for supporting the crankcase 26, and the structure for simply attaching the crankcase 26 to the seat pillar tubes 6, 6 becomes simple. In particular, in the case of this embodiment, the rear arm 11 is supported on the rear part of the crankcase 26 by the pivot bracket 40, and the crankcase 26 is connected to the frame by using the pivot bracket 40, which reduces the number of parts. This not only simplifies the structure but also saves assembly time. Furthermore, this pivot shaft 4 is the point of action of the load along the front and rear direction transmitted from the rear arm 11, and since the crankcase 26 is connected to the frame 10 at this point of action, the front part of the crankcase 26 and Coupled with crank case 2
This eliminates the occurrence of twisting in 6. Note that when the rear arm 11 is pivotally supported on the crankcase 26, the position of the rear arm 11 is set with the crankcase 26 as a reference, making it easier to define the spacing accuracy between the chain sprockets 51 and 52.

According to the present invention described in detail above, even if a load in the longitudinal direction due to the swinging of the rear arm or a load due to the reaction force of the chain is applied to the engine crankcase, these loads are transferred through the front and rear portions of the crankcase. Since the load is distributed and transmitted to the frame in a substantially linear manner, the unevenness of the load is suppressed, and twisting of the engine and moment generation at the mounting portion can be reliably prevented.

Moreover, since the rear arm is pivoted directly to the crankcase, there is no need for a special structure for pivoting the rear arm on the frame side, and the connection point between the rear of the engine and the frame is simply a structure where the engine is attached to the frame. This has the advantage of simplicity.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view of the frame, FIG. 2 is a view along the Rolo line in FIG. 1, and FIG.
The figures are a cross-sectional view taken along the line mm in Fig. 1, Fig. 4 is an enlarged side view showing the mount portion at the rear of the crankcase, and Fig. 5 is an enlarged side view showing the mount portion at the rear of the crankcase.
The figure is a sectional view taken along the line V-V in FIG. 4, and FIG. 6 is a view taken along the Nakamachi line in FIG. 1. 10... Frame, 11... Rear arm, 15... Rear wheel, 25
...engine, 26...crankcase, 51...driving side chain sprocket, 52...driven side chain sprocket, 53...chain. Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 Mountain boat

Claims (1)

[Claims] 1. A frame is divided at the front and rear of the crankcase of the engine, and the front and rear parts of the crankcase are installed by spanning between the divided frames. In a chain-driven motorcycle in which a chain is wound between a driving side chain sprocket and a driven side chain sprocket of a rear wheel that is pivotally supported on the rear end of the rear arm, the front end of the rear arm is attached to the rear of the crankcase. The diamond frame is pivotably supported and is characterized in that a mounting portion for attaching the front part of the crankcase to the frame and the drive-side chain sprocket are respectively provided on a substantially extended line passing through the pivot point of the rear arm. A chain-driven motorcycle equipped with 2. A chain drive type with a diamond frame according to claim 1, characterized in that a suspension device is installed between the upper front part of the frame and the upper part of the rear arm through above the engine. Motorcycle. 3. Claim 1 or 2, characterized in that the pivot shaft for pivotally supporting the rear arm to the crankcase is connected to the frame and also has the function of connecting the crankcase to the frame. A chain-driven motorcycle with a diamond frame.