JPH0633071B2 - Rear fork mounting structure for motorcycles - Google Patents

Description

The present invention relates to a rear fork mounting structure for a motorcycle.

Recently, various modifications have been attempted and adopted for a rear wheel suspension system using a link type progressive suspension in order to further improve performance and reduce weight.
In the case of a rear fuk (hereinafter referred to as swing arm 1) in the current type progressive suspension as shown in FIG. 1, its front end is pivotally supported on the pivot shaft 2 of the vehicle body, and its rear end is attached to the rear wheel 4 by the axle 3. The pivot shaft 2 swings around the pivot shaft 2 by the vertical stroke of the rear wheel 4.

The assembly relationship between the swing arm 1 and the cushion unit 5 with a built-in oil damper is as follows.
The first link 6 of the two links 6 and 7 is connected to the bracket 8 fixed to the lower part of the swing arm 1 by a pin 9 so as to be pivotable, and the other end To the lower operating end of the cushion unit 5 with pin 1
At 0, it is still pivoted. Then, the other second link 7 is pivotally supported at one end thereof on the vehicle body side by a pin 12, and
The other end is pivotally supported on the first link 6 by a pin 11, and the first link 6 is eventually connected to the swing arm 1, the cushion unit 5, and the second link 7 by the pins 9, 10, 1.
All three of these members are connected by a number 1 for convenience, and the relationship between all these members forms a link mechanism that can rotate with respect to each other.

Therefore, when the swing arm 1 swings by the mechanism, that is, when the rear wheel 4 sinks, the swing arm 1 rotates in the counterclockwise direction in the figure with the pivot shaft 2 as the swing fulcrum. The first link 6 is suitable for pulling up both the second link 7 and the cushion unit 5, and the cushion unit 5 is actuated by the push-up of the first link 6 to function as a so-called shock absorber.

However, in the above structure and function, it is the current situation that the connection between the swing arm 1 and the first link 6 must intervene with the attachment bracket 8 with the peripheral members.

Therefore, the present invention has been made in view of the conventional structure as described above, and an object thereof is to remove the bracket 8 to reduce the weight and size and to achieve a more effective function. Is to provide a rear fork mounting structure for a motorcycle.

Another object of the present invention is to provide a rear fork mounting structure that takes into consideration deterioration of lubrication performance of link sliding parts.

Therefore, the present invention is characterized by the following structure. That is, in the rear fork mounting structure of a motorcycle, in which the swing motion of the left and right rear forks starting from the pivot axis of the vehicle body is transmitted to the cushion unit, one end of which is located on the central axis of the rear fork. Alternatively, a first link member pivotally supported in the vicinity thereof and the other end thereof pivotally supported on a lower operating end of the cushion unit, and one end of the first link member pivotally supported and the other end of the vehicle body A second link member pivotally supported on the side, and a cross member fixedly installed between the left and right rear forks to form a gutter-shaped portion that opens downward and extends in the vehicle body left-right direction, It is characterized in that the one end of the first link member is disposed in the recess of the trough portion and is pivotally supported by a shaft member.

Hereinafter, the structure of an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, the common parts among the additional symbols given in FIG. 1 are the same first members. 2 and 3, reference numeral 13 in the drawings denotes a cushion unit which is a first link member, and the upper end portion of the arm 13 is on the central axis A-A of the swing arm 1 or as shown in the figure. A pivot pin is rotatably supported by a connecting pin 14 near the lower side, and a lower end is pivotally supported by a lower pin 5a of the cushion unit 5 by a connecting pin 15. On the other hand, one end of the cushion connecting rod 16 which is the second link member is fixed to the vehicle body side near the main stand (see FIG. 1) by a fixing pin 17
Is rotatably supported by and the other end is rotatably supported by a connecting pin 18 at a substantially intermediate portion of the cushion arm 13.

Next, in the mounting structure of the cushion arm 13 to the swing arm 1 by the pin 14, as shown in FIG. 3 in which the portion is viewed from below, the reinforcing cross member 19 that crosses the swing arm 1 is attached to the support bracket. As a substitute, the cross member 19 is rotatably supported by the arm collar 20 and the bearing 21. 1 in the figure
Reference numeral 4 is a bolt shaft as a turning pin. Reference numeral 22 denotes a seal and packing member.

The rotation loci of the connecting pins 14, 15 and 18 that pivotally support the respective members of the link mechanism constructed as described above are shown as in FIG. According to this, the connection point between the cushion arm 13 and the swing arm 1 is the central axis A-.
The meaning of being provided on or in the vicinity of A is that the pivot pin 2 of the swing arm 1 is used as a swing fulcrum and the connecting pin 1
Rotation locus lines (I) and (II), which will be described later, that act on the connecting portion of No. 4.
The separation ratio is reduced as compared with the case of the conventional mechanism, and thus the degree of freedom in design for progressive suspension characteristics is increased. That is, when the swing arm 1 sinks, the distance between the connecting pin 14 and the connecting pin 18 relatively increases, and the turning locus line (I) of the connecting pin 14 and the turning locus line (II) of the connecting pin 18 (II). ) Are gradually separated from each other, and this is the ratio of the stroke amount due to the depression of the axle 3 (see FIG. 1) and the contraction amount of the cushion spring with a constant constant in the cushion unit, that is, the normal suspension characteristic is relatively large. This means that the cushion unit 5 is weak at the so-called beginning of action, and the progressive effect of the spring is increased as a strong external force acts. Therefore, the fact that the separation ratio of the rotation locus lines can be reduced as in the present invention increases the degree of freedom in designing for setting the progressive effect. In addition, the link members 13, 16
Is located higher than the conventional one, and it is possible to reduce projections around the lower part of the vehicle.

As is apparent from the above description, according to the present invention, it is applied to a rear fork mounting structure known as a link type progressive suspension mechanism to exert its effect remarkably, and specifically, a cushion arm such as a conventional type is used. Of the cushion arm is removed and the connecting point of the cushion arm to the rear fork is pulled up to or near the center axis of the rear fork, and the reinforcing cross member is used as a cover for the cushion arm connecting section to remove dust from the connecting section. It is possible to prevent the adhesion of mud, etc., and to secure a good pivotal condition.

As described above, desired lubrication characteristics can be maintained and maintenance is preferable while reducing weight and size by reducing members such as brackets, and the degree of freedom in setting a function called a progressive effect can be increased. is there.

[Brief description of drawings]

FIG. 1 is a partial side view of a motorcycle having a conventional rear fork mounting structure, and FIGS. 2 to 4 are side views of essential parts showing a structure of an embodiment of the present invention and a part viewed from above. FIG. 6 is a cross-sectional view and an action diagram showing a rotation locus of each connection point as a link mechanism. Explanation of symbols of main parts 1 …… Swing arm 2 …… Pivot shaft 3 …… Axle 4 …… Rear wheel 5 …… Cushion unit 6,13 …… Cushion arm as first link member 7,16 …… Second Cushion connecting rod as a link member 8 ... Cushion arm support bracket 14, 15, 18 ... Connecting pin A-A line ... Swing arm center axis 19 ... Cross member 20 ... Cushion arm collar 21 ... Bearing

Claims (1)

[Claims] 1. A rear fork mounting structure for a motorcycle, wherein a swinging motion of left and right rear forks starting from a pivot shaft of a vehicle body is transmitted to a cushion unit, one end of which is mounted on the rear fork. A first link member pivotally supported on or near the central axis and having the other end pivotally connected to the lower operating end of the cushion unit; and one end of the first link member pivotally supported and the other end thereof. A second link member pivotally supported on the vehicle body side, and a gutter-shaped portion that opens downward and extends in the vehicle body left-right direction is formed on a cross member that is fixedly installed between the left and right rear forks. A rear fork mounting structure for a motorcycle, wherein the one end of the first link member is disposed in the recess of the gutter-shaped portion and is pivotally supported by a shaft member.