KR100472323B1 - Rear swing arm of motorcycle - Google Patents

Abstract

By connecting the pivot shaft attachment portions 53 and 53 with the cross member 54 and attaching the reinforcement 57 integrally to the base 51, the suspension attachment portion (from the pivot shaft attachment portion 53) ( By 58), the torsional rigidity and the longitudinal bending rigidity are high, and the arm portion 55 is formed so as to be convex downward from the side by using a square pipe when viewed from the cross-section. The arm portion 55 has a high torsional rigidity and a low longitudinal rigidity.

While maintaining sufficient rigidity for the rear swing arm, it is difficult to be absorbed by the suspension and the shock can be reduced continuously and rapidly.

Description

REAR SWING ARM OF MOTORCYCLE}

The present invention relates to a rear swing arm of a motorcycle.

In a two-wheeled vehicle, the weight balance before and after the vehicle body changes slightly depending on the size of the engine attached to the vehicle body frame, the attachment position, and the like, thereby affecting the maneuverability and the riding comfort. Therefore, the front fork or the rear swing arm which hangs before and after the engine and the body frame becomes an important factor in controlling the maneuverability and the ride comfort. For example, in the rear swing arm, in order to match with the engine or the body frame, a rear swing arm having a rigid rigidity and high rigidity is required on one side, and a rear swing arm having a soft characteristic on the other side may be required.

However, stiffness is a deformation resistance against a load, and generally means torsional rigidity and flexural rigidity.

Torsional stiffness is defined as the integral of the shear modulus of elasticity (G) and the cross-sectional secondary pole moment (l _P ) for straight rods of uniform cross section. It is an indicator. The flexural stiffness is defined as the integral of the longitudinal modulus of elasticity (E) and the cross-sectional secondary moment (1) in the case of straight rods of uniform cross section, and is an indicator in making the rear swing arm soft.

However, the torsional stiffness and the bending stiffness are correlated, and when the torsional rigidity is improved, the bending stiffness is also improved.

As a rear swing arm of a motorcycle in consideration of torsional rigidity and flexural rigidity, for example, ① Japanese Patent Application Laid-Open No. 4-314683, "Motor Swing Arm," and Japanese Utility Model Registration No. 2536050, "Reinforced Hollow Structure for Vehicles." Structure ”is known.

1 is a rear swing in which the arm pipe 5 having a concave curved surface 11 extends backward from the body 4 on which the pivot hole 3 and the shaft hole 1 are formed. It is an arm.

2 is a rear swing arm formed by the letter "K" when viewed from the side according to FIG.

It can be said that a soft characteristic is required in the rear swing arm of the above ①, and in some cases, the rigidity may not be sufficient.

The above-mentioned rear swing arm can be said to be able to obtain a rigid property with high rigidity, and rigidity is required, but for this reason, the rear swing arm may lack soft characteristics.

In other words, there is a demand for a technique capable of having a soft characteristic while maintaining sufficient rigidity for the rear swing arm.

Accordingly, it is an object of the present invention to provide a rear swing arm that combines smooth characteristics while maintaining sufficient rigidity.

In order to achieve the above object, the rear swing arm of the motorcycle according to claim 1 has a pivot shaft attachment portion that is rotatably attached to the vehicle body frame via a pivot shaft, and a suspension attachment portion is provided at the rear of the pivot shaft attachment portion. A rear swing arm having a rear wheel support portion supporting rear wheels at the rear end of an arm portion extending backward from the attachment portion, wherein the structure between the pivot shaft attachment portion and the suspension attachment portion has a high torsional rigidity and longitudinal bending rigidity. At the same time, the arm portion is characterized by having a high torsional rigidity and a low longitudinal stiffness.

By setting the torsional rigidity and the longitudinal bending rigidity high between the pivot shaft attachment portion and the suspension attachment portion, sufficient rigidity is maintained for the rear swing arm. As a result, the maneuverability can be improved.

By setting the torsional rigidity high and the longitudinal bending rigidity low, the arm portion maintains sufficient rigidity for the rear swing arm, for example, is difficult to absorb by the suspension, and facilitates the continuous and rapid repeated shock. As a result, the riding comfort can be improved.

Claim 2 is characterized in that the rear wheel support has a structure with high torsional rigidity and longitudinal bending rigidity.

By increasing the rear wheel support torsional rigidity and the longitudinal bending rigidity, the rear wheel can be firmly supported. As a result, the maneuverability can be improved.

Claim 3 was formed so that an arm part might become convex downward when viewed from the side.

By setting the torsional rigidity from the pivot shaft attachment portion to the suspension attachment portion and the longitudinal bending rigidity high and forming the arm portion convex downward when viewed from the side, for example, the arm portion from the pivot shaft attachment portion to the suspension attachment portion is formed. It can be approximated to the behavior of the cantilever bending beam when fixed. In general, in the cantilever bending beam formed in the lower convex shape, it becomes easy to bend under the load from below, and it becomes difficult to bend under the load from the upper side.

That is, since the load in the longitudinal direction that the rear swing arm receives from the rear wheel is mainly the load from the lower side, the arm swing is formed to be convex downward when viewed from the side, thereby maintaining the torsional rigidity while maintaining the torsional rigidity. Can be set low. As a result, while maintaining sufficient rigidity for the rear swing arm, it is difficult to absorb by the suspension, and the shock that is repeated continuously and rapidly can be achieved.

In addition, by forming the arm portion so as to be convex downward when viewed from the side, interference with other vehicle body parts, for example, when swinging, is prevented, so as to secure a large swing angle of the rear swing arm.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, the figure shall be seen in the direction of the sign.

1 is a side view of a motorcycle equipped with a rear swing arm according to the present invention.

The motorcycle 10 is an example of an off-road bike. The body frame 11 and the head pipe 12 provided at the front of the body frame 11 and the head pipe 12 are rotatable. The front forks 13, 13 and 13 inside are not shown, the handle 14 attached to the top of the front forks 13, 13, and the lower part of the front forks 13, 13 are rotatable. The front wheel 15 attached, the front fender 16 which covers this front wheel 15, the fuel tank 17 attached to the vehicle body frame 11 behind the head pipe 12, and this fuel tank 17 ), A power unit 22 composed of a seat 18 provided at the rear of the engine, an engine 19 and a transmission 21 arranged below the fuel tank 17 and the seat 18, and the power unit 22. Rear swing arm 50 that is swingably attached to the vehicle body frame 11 from the rear of the head), and is rotatably attached to the rear swing arm 50 and driven by the power unit 22. The rear wheel 24 and the rear fender 25 provided in the upper part of this rear wheel 24 are comprised.

Here, 26 is the radiator shroud, 27 is the side cover, 28 is the suspension, 29 is the exhaust pipe, 31 is the silencer, 32 is the caliper, 33 is the pivot shaft, 23 is the drive chain, 35 is the axle of the front wheel 15, 36 Is the axle of the rear wheel 24.

Moreover, the rear swing arm 50 of the motorcycle which concerns on this invention is a rear swing arm which combines the soft characteristic, maintaining sufficient rigidity as mentioned later.

2 is a perspective view of a vehicle body frame to which a rear swing arm of a motorcycle according to the present invention is attached.

The vehicle body frame 11 extends a pair of main frames 41 and 41 from the head pipe 12 to the left and right rearwards, and lowers the front end portions 42 and 42 of the main frames 41 and 41 to form a head pipe ( 12 extends the down tube 43 downward, extends a pair of parallel tubes 44 and 44 from the middle of the down tube 43 to the left and right, and the front end of the parallel tubes 44 and 44, and The front end portions 42 and 42 of the main frames 41 and 41 are connected to form two connecting portions 46 and 46, and the cross tubes 47 are interposed between the connecting portions 46 and 46. In addition, 48 and 48 (48 on one side are not shown) are through-holes of the pivot shaft 33, and 49 are reinforcement pipes extending from the down tube 43 to the main frames 41 and 41. FIG.

3 is a plan view of a rear swing arm of a motorcycle according to the present invention.

The rear swing arm 50 forms a pair of right and left protrusions 52 and 52 forward from the base 51, and pivot pivot attachment portions 53 and 53 are formed at the ends of these protrusions 52 and 52. And between these pivot axis attachment parts 53 and 53 is connected by the cross member 54, the left and right pair of arm parts 55 and 55 are extended back from the base 51, and the arm part 55 , The rear wheel support portions 56 and 56 formed thick at the front end of each of the upper and lower ends of the base 51, and the reinforcing material 57 is integrally attached to the upper surface of the base 51, and the suspension attachment portion (below the base 51). 58, 58).

Fig. 4 is a side view of the rear swing arm of the motorcycle according to the present invention, and the arm portion 55 is formed so as to be convex in a downward shape when viewed from the side in a square pipe in cross section, and from the base 51 to the rear wheel support portion ( Tapered towards 56). As will be described later, the load in the longitudinal direction that the rear swing arm 50 receives from the rear wheel 24 (see FIG. 1) is mainly convex downward when the arm portion 55 is viewed from the side because the load from the lower side is mainly applied. By forming so that the torsional rigidity is high, the bending rigidity in the longitudinal direction can be set low. Moreover, the bending part R2 of the lower surface was set smaller than the bending radius R1 of the upper surface, and the arm part 55 was made into a thin shape.

The rear swing arm 50 has a pivot shaft attachment portion 53, 53 (inside 53 not shown) that rotatably attaches to the vehicle body frame 11 (see FIG. 2) via the pivot shaft 33. Suspension attachment portions 58, 58 (inner 58 not shown) are provided behind the pivot shaft attachment portions 53, 53, and arm portions 55 extending rearward from the suspension attachment portions 58, 58. 55, the inner 55 is not shown) in the rear swing arm having rear wheel supports 56, 56 (inner 56 is not shown) supporting the rear wheels 24 (see FIG. 1) at the rear end. Between the parts 53 and 53 with the cross member 54, and by attaching the reinforcing material 57 integrally to the base 51, between the pivot axis attachment part 53 and the suspension attachment part 58 Is a structure with high torsional rigidity and longitudinal bending rigidity, and when the arm part 55 is viewed from the cross section, a square pipe is used, and By looking formed so as to be convex downwardly from, one to the arm 55 to lower bending rigidity in the vertical direction with high torsional rigidity structure.

Between the pivot shaft attachment portion 53 and the suspension attachment portion 58, the torsional rigidity and the longitudinal bending rigidity are set high, thereby maintaining sufficient rigidity for the rear swing arm 50. As a result, the maneuverability can be improved.

By setting the torsional rigidity high and the longitudinal bending rigidity low, the arm portion 55 maintains sufficient rigidity for the rear swing arm 50, for example, is difficult to absorb in the suspension 28, and repeats continuously and rapidly. We plan to alleviate shock that we become. As a result, the riding comfort can be improved. That is, the rear swing arm 50 which has a soft characteristic while maintaining sufficient rigidity can be realized.

That is, in order to set the torsional rigidity of the arm part 55 high and to make the bending rigidity of a longitudinal direction low, the arm part 55 was formed so that it might become convex downward when viewed from the side. As described later, the torsional rigidity from the pivot axis attachment portion 53 to the suspension attachment portion 58 and the longitudinal bending rigidity are set high, and the arm portion 55 is formed to be convex downward when viewed from the side. The rear swing arm 50 can approximate the behavior of the cantilever bending beam when the pivot shaft attachment portion 53 is fixed to the suspension attachment portion 58. Generally, in the cantilever bending beam formed in the downward convex shape, it becomes easy to bend under the load from below, and becomes difficult to bend under the load from above.

Since the load in the longitudinal direction that the rear swing arm 50 receives from the rear wheel 24 (refer to FIG. 1) is mainly a load from the bottom, the torsional force is formed by forming the arm portion 55 so as to be convex downward when viewed from the side. The stiffness in the vertical direction can be set low while maintaining the stiffness high. As a result, while maintaining sufficient rigidity for the rear swing arm 50, it is difficult to absorb in the suspension 28 (refer to FIG. 1), and it is possible to alleviate the impact which is repeated continuously and rapidly.

The rear swing arm 50 has a rear wheel support portion 56 formed thick at the distal end of the arm portion 55, so that the rear wheel support portion 56 has a high torsional rigidity and longitudinal bending rigidity. Can be.

The torsional rigidity and the longitudinal bending rigidity are made high by the rear wheel support part 56, so that the rear wheel can be firmly supported. As a result, the maneuverability can be improved.

The operation of the rear swing arm 50 described above will be described next.

5 (a) and 5 (b) are comparative explanatory views of the rear swing arms of the motorcycle according to the present invention, (a) shows the rear swing arm 100 of the comparative example, and (b) is the embodiment The rear swing arm 50 is shown.

However, since the torsional stiffness and the bending stiffness are generally correlated, increasing the torsional stiffness also increases the bending stiffness. Torsional stiffness is indispensable for the stability of the vehicle body. When the torsional rigidity of the rear swing arm is improved, the bending stiffness is also improved. However, when the rear swing arm (especially the longitudinal bending rigidity of the arm portion) is high, the rear swing arm is affected by the damper of the suspension in the region where the operation of the rear swing arm is accelerated (that is, the road surface where the irregularities are repeated). Followability of the arm may be slowed down. As a result, it causes a deterioration of ride comfort and maneuverability.

Therefore, it is preferable if the torsional rigidity can be improved while maintaining the longitudinal bending rigidity as in the prior art.

In (a), the rear swing arm 100 of the comparative example forms a pair of left and right protrusions 102 and 102 forward from the base 101, and pivot axis attachment portions are formed at the ends of these protrusions 102 and 102. Rear wheel support portions (103, 103) formed, extending from the base portion (101) to the rear left and right arm portions (105, 105), and thickly formed at the ends of these arm portions (105, 105), respectively. 106 and 106 are rear swing arms of a general shape.

In (b), the rear swing arm 50 of the embodiment connects between the pivot shaft attachment portions 53, 53 to the rear swing arm 100 shown in (a) with a cross member 54, and By forming the arm parts 55 and 55 convex downward, forming the rear wheel support parts 56 and 56 thickly, and improving so that the reinforcing material 57 may be integrally attached to the upper surface of the base 51, It is a rear swing arm which improves only torsional rigidity, maintaining the longitudinal bending rigidity substantially the same as the rear swing arm 100 of a comparative example.

Moreover, as described in the following figure, it is a rear swing arm which can ensure the swing angle of the rear swing arm 50.

6 (a) to 6 (c) are first explanatory diagrams of the rear swing arm of the motorcycle according to the present invention, (a) shows the rear swing arm 110 of Comparative Example 1, and (b ) Shows the rear swing arm 120 of Comparative Example 2, and (c) shows the rear swing arm 50 of the embodiment.

In (a), the rear swing arm 110 is a rear swing arm formed in a straight line when the arm portion 115 is viewed from the side.

In (b), the rear swing arm 120 is a rear swing arm formed so as to be convex upward when the arm portion 125 is viewed from the side, and the height H from the horizontal level of the center of the pivot shaft attachment portion 123 is high. ), And the swing angle when the rear swing arm 120 is swinged as shown by the arrow b is? 2.

In (c), the rear swing arm 50 is a rear swing arm formed so that the arm part 55 becomes convex downward when viewed from the side, and from the horizontal level of the center of the pivot axis attachment part 53, (b) It is assumed that there is a member on the side of the vehicle body at the same height H as the swing angle, and the swing angle when the rear swing arm 50 is swinged as shown by the arrow b is θ.

In (b) and (c), when the swingable angle θ2 of the rear swing arm 120 and the swing angle θ of the rear swing arm 50 are compared, it is clear that θ> θ2, and the rear swing arm ( Since the arm portion 55 is formed to be convex downward when viewed from the side, interference with other vehicle body parts can be prevented when swinging, and the swing angle of the rear swing arm 50 can be increased. . In other words, the rear swing arm 50 may be referred to as a swing arm suitable for off-road bikes that require a large swing angle. As a result, the design of the motorcycle 10 (refer FIG. 1) and the freedom of design can be expanded.

In addition, the cross-sectional shape of the same distance from each base 111, 121, 51 has the same cross section, and the influence by the process of the arm parts 115, 125, 55, for example, work hardening and thermal deformation, etc. It shall not be.

Further, in (a) to (c), the rear swing arms 110 and 120 are integrally attached to the base 111 and 121 with the reinforcing material 57 and equivalents to the pivot shaft attachment portions 113 and 123. It is a product equivalent to the cross member 54, and the rear wheel support part 56 and the same product which were formed thick were attached to the front-end | tip of the arm part 115,125.

Here, since the influence of the damper of the suspension is considered in the region where the followability of the rear swing arms 110, 120, 50 is slowed down, the rear swing arms 110, 120, 50 are approximately (a) to ( The bases 111, 121, 51 shown in c) are fixed, and can be seen as a cantilever beam when a predetermined load W is applied from the lower end portion of the arm portions 115, 125, 55 to the rear swing arm ( The deformation resistance (vertical bending stiffness) of 110, 120, and 50 is discussed in the following figure.

In addition, L represents the distance from the support point A in the case where the arm parts 115, 125, 55 are regarded as a cantilever beam and the point B to which the predetermined load W is applied.

7 (a) to 7 (c) are explanatory views of the second action of the rear swing arm of the motorcycle according to the present invention, (a) shows the rear swing arm 100 of Comparative Example 1, and (b ) Shows the rear swing arm 120 of Comparative Example 2, and (c) shows the rear swing arm 50 of the embodiment.

In (a), when the arm part 115 is a general simple column (straight beam), when the predetermined load W from below is applied, the deformation amount (delta) 1 arises. For example, the same deformation amount δ1 is generated even when a predetermined load W is applied from above.

In (b), the arm portion 115 generates a deformation amount δ2 smaller than the deformation amount δ1 shown in (a) with respect to the predetermined load W from the lower side in the convex bending beam.

In (c), the deformation amount δ2 greater than the deformation amount δ1 shown in (a) occurs with respect to the predetermined load W when the arm portion 55 is convex downwardly. That is, the relationship between the deformation amounts shown in (a) to (c) is δ2 <δ1 <δ3.

As described above, since the bending stiffness is a deformation resistance, the smaller the deformation amount, the smaller the bending stiffness.

The load received by the rear swing arm is a load from below which is received when the rear wheel is grounded to the ground, and the load from above is not a problem.

Therefore, as shown in (c), the arm 55 is formed as a convex bent beam downward to have a directional stiffness in the longitudinal direction, so that the bending stiffness of the arm 55 is increased even when the arm 55 is increased. Flexural rigidity can be reduced. As a result, the rear swing arm 50 having smooth characteristics can be realized while maintaining sufficient rigidity.

Moreover, in embodiment, as shown in FIG. 4, although the bending radius R2 of the lower surface was set smaller than the bending radius R1 of the upper surface, the arm part was made into a thin shape, but it does not restrict to this, In the case where the bending radius of the upper surface is included in the bending radius of the upper surface, the tip may be formed by changing the center of the bending radius of the lower surface to the center of the bending radius of the upper surface.

In addition, in the embodiment, as shown in FIG. 4, in order to improve the torsional rigidity, the cross member 54, the reinforcing material 58, and the rear wheel support portions 56 and 56 having increased thickness are used, but the torsional rigidity is improved. The means for making it is not limited to this, but also the cross member 54, the reinforcement material 58, and the rear wheel support parts 56 and 56 which increased the thickness are arbitrarily combined, and the thickness of the rear swing arm increases, and It may be due to a change of material or the like.

This invention exhibits the following effects by the said structure.

In Claim 1, since the torsional rigidity and the longitudinal bending rigidity were set high between the pivot axis attachment part and the suspension attachment part, sufficient rigidity can be maintained for a rear swing arm. As a result, the maneuverability can be improved. Moreover, since the arm part has set the torsional rigidity high and the longitudinal bending rigidity low, for example, while maintaining sufficient rigidity for a rear swing arm, it is hard to absorb by a suspension, and it aims at alleviating the impact which repeats rapidly and continuously. As a result, the riding comfort can be improved. In other words, it is possible to realize a rear swing arm having a smooth characteristic while maintaining sufficient rigidity.

In Claim 2, since the torsional rigidity and the longitudinal bending rigidity were made high, the rear wheel support part can firmly support a rear wheel. As a result, the maneuverability can be improved.

In Claim 3, since the arm part was formed so that it might become convex downward from the side, for example, it can approximate the behavior of a cantilever bending beam when the arm part is fixed from a pivot shaft attachment part to a suspension attachment part. In general, in the cantilever bending beam formed in the lower convex shape, it becomes easy to bend under the load from below, and becomes difficult to bend under the load from the upper side.

That is, since the load in the longitudinal direction that the rear swing arm receives from the rear wheel is mainly the load from the lower side, the arm swing is formed to be convex downward when viewed from the side, thereby maintaining the torsional rigidity while maintaining the torsional rigidity. Can be set low. As a result, while maintaining sufficient rigidity for the rear swing arm, it is difficult to absorb by the suspension, and the shock that is repeated continuously and rapidly can be achieved.

In addition, since the arm portion is formed to be convex downward when viewed from the side, interference with other vehicle body parts can be prevented, for example, when swinging, and the swing angle of the rear swing arm can be largely secured. As a result, the design of a motorcycle and the degree of freedom of design can be expanded.

1 is a side view of a motorcycle equipped with a rear swing arm according to the present invention;

2 is a perspective view of a vehicle body frame to which a rear swing arm of a motorcycle according to the present invention is attached;

3 is a plan view of a rear swing arm of a motorcycle according to the present invention;

4 is a side view of a rear swing arm of a motorcycle according to the present invention;

5 is a comparative explanatory diagram of a rear swing arm of a motorcycle according to the present invention;

6 is a first operation explanatory diagram of a rear swing arm of a motorcycle according to the present invention;

7 is an explanatory view of a second action of the rear swing arm of the motorcycle according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: two-wheeled vehicle 11: the body frame

33: pivot axis 50: rear swing arm

53: pivot shaft attachment portion 55: arm portion

56: rear wheel support 58: suspension attachment portion

Claims (3)

A pivot shaft attachment portion that rotatably attaches to the vehicle body frame through a pivot shaft, and a suspension attachment portion is provided on the base of the rear of the pivot shaft attachment portion, and the rear wheel is supported on the rear end of the arm portion extending rearward from the suspension attachment portion. In the rear swing arm having a rear wheel support, The pivot shaft attachment portion is connected by a cross member, a reinforcing material is attached to the base on the opposite side of the suspension attachment portion, and the arm portion is formed to be convexly shaped downward from the side. Swing arm. The method of claim 1, A rear swing arm for a motorcycle, characterized in that the arm is a rectangular pipe when viewed from a cross section and has a shape that the end thereof is thinner from the base toward the rear wheel support. The method of claim 2, A rear swing arm of a motorcycle, characterized in that the radius of curvature of the lower surface is set smaller than the radius of curvature of the upper surface of the arm portion formed in a convex shape.