JP4648769B2 - Inverted front fork - Google Patents

Description

  The present invention relates to an improvement of an inverted front fork.

A conventional inverted front fork is known in which the cross-sectional shape of the outer tube is different between a position in the vehicle longitudinal direction and a position in the vehicle width direction (see, for example, Patent Document 1).
JP 2000-18303 A

  As shown in FIGS. 2 and 4 of Patent Document 1, the front fork 4 has a pair of left and right outer tubes 40, 40 connected by an upper bracket 50 and a lower bracket 51, and an inner tube is connected to each outer tube 40 from below. 41 is slidably inserted, and a portion in the vehicle width direction of the outer peripheral surface below the lower bracket 51 of each outer tube 40 is cut to form the cutting surfaces 40a and 40b.

  Thus, by forming the cutting surfaces 40a and 40b in the vehicle width direction portion of the outer peripheral surface of the outer tube 40, the bending rigidity is kept high without reducing the cross-sectional shape of the front fork 4 in the vehicle front-rear direction. However, the cross-sectional shape in the vehicle width direction is reduced to reduce the bending rigidity, ensuring a firm feeling against the load in the vehicle front-rear direction acting on the front fork 4 during braking, and the vehicle width direction acting on the front fork 4 during cornering. Improve impact absorption against load.

  In FIG. 1 of Patent Document 1, a load acts on the lower end of the front fork 4 via the front wheel 3. Since the front fork 4 has a predetermined caster angle, the grounding point of the front wheel 3, that is, the point at which a load is applied to the front fork 4, is shifted to the rear of the vehicle with respect to the intersection of the extension line of the front fork 4 and the ground. Therefore, the present inventors have questioned whether or not the rigidity of the outer tube 40 is simply reduced when a load in the vehicle width direction acts on the lower end of the front fork 4, and confirmed by experiments. The experimental method will be described below.

FIGS. 11A to 11C are explanatory views showing a procedure for confirming the rigidity of the front fork.
(A) is a side view of the experimental apparatus 100. The experimental apparatus 100 is attached to an inverted front fork 101, an axle 102 attached to the lower end of the front fork 101, and extending downward on the axle 102. The top bridge 105 and the bottom bridge 106 constituting the front fork 101 are constrained, the stroke of the inner tube 108 with respect to the outer tube 107 is locked, and a predetermined load is applied horizontally to the lower end of the bar 103. . A weighting point 111 provided for applying a load to the bar 103 corresponds to a grounding point of the front wheel 112 supported by the front fork 101.

FIG. 2B is a front view of the experimental apparatus 100. FIG. Reference numeral 115 denotes a steering stem.
(C) is a c arrow view of (b). The direction in which the load is applied to the bar 103 (see (a)) is an angle of 0 ° at the rear of the vehicle and an angle of 90 ° at the side of the vehicle.

FIGS. 12A and 12B are first explanatory views showing a deformed state when a load is applied to the front fork.
In (a), when a load is applied in an angle 0 ° direction (vehicle rear), the lower portion of the outer tube 107 and the inner tube 108 bend toward the vehicle rear (right side in the figure).
(B) is a b arrow view of (a), and the lower part of the left and right outer tubes 107 and the left and right inner tubes 108 are bent rearward by the same amount.

FIGS. 13A and 13B are second explanatory views showing a deformed state when a load is applied to the front fork.
In (a), when a load is applied in the direction of 90 ° angle (vehicle side, direction from the front side to the back side), the outer tube 107 and the inner tube 108 on the front side are rearward of the vehicle from those on the back side. It is bent greatly.

  (B) is a view taken in the direction of arrow b in (a), where the lower portion of the front fork 101 is twisted as indicated by an arrow A, and a large twist as indicated by an arrow B occurs in the outer tube 107 itself on the near side. Yes.

  Thus, the front fork 101 is twisted by the load in the vehicle width direction, and the outer tube 107 not only simply bends in the vehicle width direction, but also the front 107a side outwards of the vehicle body and the back surface 107b side is in the vehicle body. Twist to move toward.

14 (a) and 14 (b) are operation diagrams for explaining the rigidity of a conventional front fork.
(A) shows the cross section of the outer tube 121 with which the conventional front fork is equipped. The outer tube shown in Patent Document 1 has the same structure.
The outer tube 121 is formed by forming cutting surfaces 121a and 121b at portions of the outer peripheral surface in the vehicle width direction. In the figure, an arrow (FRONT) indicates the front side of the vehicle, and an arrow (IN) indicates the inner side of the vehicle. Since the outer tube 121 has a long section in the vehicle front-rear direction (the direction of the arrow (0 °) in the figure), the section moment in the section is large and the bending rigidity is large.

  In FIG. 13B, when a load in the vehicle width direction (arrow (90 ° direction in the figure)) is applied to the outer tube 121, the outer tube 121 is similar to that described with reference to FIG. Twisted in the direction of arrow C from this state. In this state, the portion in the vehicle width direction of the outer peripheral surface of the outer tube 121 (that is, the portion indicated by the points D and E) includes a portion other than the cutting surfaces 121a and 121b. The bending rigidity in the vehicle width direction at this time does not greatly decrease with respect to the bending rigidity in the vehicle front-rear direction in (a).

  That is, even if the cross-sectional secondary moment of the outer peripheral surface of the outer tube 121 in the vehicle front-rear direction is increased and the cross-sectional secondary moment of the outer peripheral surface of the outer tube 121 in the vehicle width direction is reduced, The decrease in the bending rigidity in the vehicle width direction with respect to the bending rigidity is small.

  In this way, considering that the outer tube 121 is twisted by the load acting in the vehicle width direction, the outer tube 121 has a small sectional moment in the vehicle width direction when the outer tube 121 is twisted. If the cross section is formed, the bending rigidity in the vehicle width direction can be greatly reduced.

  An object of the present invention is to improve the bending rigidity in the vehicle front-rear direction of the front fork and to effectively reduce the bending rigidity in the vehicle width direction by improving the inverted front fork.

According to the first aspect of the present invention, a pair of left and right outer tubes are connected by a top bridge and a bottom bridge, supported by the vehicle body side by these top bridges and bottom bridges, and inserted into the lower portions of the outer tubes movably. In an inverted front fork that supports a front wheel with a pair of inner tubes, on the outer peripheral surface of the outer tube and on the front surface of the outer tube from the vehicle front-rear direction toward the vehicle interior, on the rear surface of the outer tube, the vehicle front-rear direction A reinforcing portion that increases the rigidity of the outer tube is provided at a position close to the outside of the vehicle body , and the reinforcing portion is provided at a position at an angle of 45 ° from the vehicle front-rear direction.

  The reinforcing section increases the sectional moment of inertia of the outer tube in the vehicle longitudinal direction, and the bending rigidity of the outer tube in the vehicle longitudinal direction is increased. In addition, when a load in the vehicle width direction is applied to the front fork from the front wheel side, the front side of the outer tube is twisted so that the front side moves to the outside of the vehicle body and the back side moves to the inside of the vehicle body. On the other hand, since it approaches the direction orthogonal, the sectional secondary moment of the outer tube in the vehicle width direction by the reinforcing portion at this time does not increase, and the bending rigidity does not increase.

Particularly in the present invention, when the load is applied in the vehicle width direction in front-fork reinforcing portion provided from the vehicle front-rear direction at the position of the angle of 45 ° is closer to the longitudinal direction of the vehicle position by twisting of the outer tube.

According to the second aspect of the present invention, a pair of left and right outer tubes are connected by a top bridge and a bottom bridge, supported by the vehicle body side by these top bridges and bottom bridges, and inserted into the lower portions of the outer tubes so as to be movable. In an inverted front fork that supports a front wheel with a pair of inner tubes, on the outer peripheral surface of the outer tube and on the front surface of the outer tube from the vehicle front-rear direction toward the vehicle interior, on the rear surface of the outer tube, the vehicle front-rear direction A reinforcing portion for increasing the rigidity of the outer tube is provided at a position close to the outside of the vehicle body, and the reinforcing portion is provided in a range between the vehicle longitudinal direction and an angle of 45 ° from the vehicle longitudinal direction. To do.
The reinforcing section increases the sectional moment of inertia of the outer tube in the vehicle longitudinal direction, and the bending rigidity of the outer tube in the vehicle longitudinal direction is increased. In addition, when a load in the vehicle width direction is applied to the front fork from the front wheel side, the front side of the outer tube is twisted so that the front side moves to the outside of the vehicle body and the back side moves to the inside of the vehicle body. On the other hand, since it approaches the direction orthogonal, the sectional secondary moment of the outer tube in the vehicle width direction by the reinforcing portion at this time does not increase, and the bending rigidity does not increase.
In particular, in the present invention, since the reinforcing portion is provided in a wide range between the vehicle longitudinal direction and an angle of 45 ° from the vehicle longitudinal direction, bending of the outer tube in the vehicle longitudinal direction is suppressed while suppressing an increase in bending rigidity in the vehicle width direction. Increased rigidity.

The invention according to claim 3 is characterized in that the lower portion of the reinforcing portion is smaller than the upper portion thereof.
The lower part of the cross-sectional area of the reinforcing part is smaller than the upper part, so that, for example, the outer tube can be compared to the upper part and the lower part of the reinforcing part with the same width as the upper part. The bending rigidity in the vehicle longitudinal direction is reduced. If the width of the lower portion is appropriately set with respect to the width of the upper portion of the reinforcing portion, the bending rigidity of the outer tube in the vehicle front-rear direction can be changed.

In the invention according to claim 1, on the outer peripheral surface of the outer tube and on the front surface of the outer tube, the vehicle is moved from the front-rear direction of the vehicle toward the inside of the vehicle body. Since the reinforcing portion that increases the rigidity of the outer tube is provided at the position, and the reinforcing portion is provided at a position at an angle of 45 ° from the vehicle longitudinal direction, the bending rigidity of the outer tube in the vehicle longitudinal direction can be enhanced by the reinforcing portion. When the load in the vehicle width direction acts on the front fork from the front wheel side, the outer tube is twisted and the reinforcing portion approaches the direction orthogonal to the load direction. The bending rigidity of can be effectively suppressed.

In particular, in the present invention, the reinforcing portion is provided at a position at an angle of 45 ° from the vehicle longitudinal direction, so that when a load in the vehicle width direction is applied to the front fork , the reinforcing portion is provided at an angle of 45 ° from the vehicle longitudinal direction. The reinforcing portion can be brought closer to the position in the vehicle front-rear direction by twisting the outer tube, and an increase in bending rigidity of the front fork in the vehicle width direction can be suppressed.

In the invention according to claim 2, on the outer peripheral surface of the outer tube and on the front surface of the outer tube, the vehicle is moved from the front-rear direction of the vehicle toward the inside of the vehicle body. Since the reinforcing portion for increasing the rigidity of the outer tube is provided at the position, and the reinforcing portion is provided in a range between the vehicle front-rear direction and the angle 45 ° from the vehicle front-rear direction, the outer tube of the outer tube is In addition to increasing the bending rigidity, when a load in the vehicle width direction acts on the front fork from the front wheel side, the outer tube is twisted and the reinforcing portion approaches the direction perpendicular to the load direction. it is possible to effectively suppress the bending rigidity in the vehicle width direction of the outer tube when, in particular in the present invention, it is possible to increase the width of the reinforcing portion, the outer While reducing the flexural rigidity in the vehicle width direction of the tube, it is possible to increase the vehicle longitudinal direction bending rigidity of the outer tube.

In the invention according to claim 3, since the cross-sectional area of the reinforcing part is smaller than the upper part, the vehicle of the outer tube is, for example, compared with the case where the upper part and the lower part of the reinforcing part have the same width. The rigidity in the front-rear direction can be reduced, and thus the rigidity of the outer tube in the vehicle front-rear direction by the reinforcing part can be appropriately changed by making the cross-sectional area of the reinforcing part different between the upper part and the lower part.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a side view of a motorcycle equipped with an inverted front fork according to the present invention. The motorcycle 10 is provided with a head pipe at the front end of a body frame 11, and a front fork 13 is attached to the head pipe so as to be steerable. In this vehicle, an axle 14 is attached to the lower end of the front fork 13, and a front wheel 16 is rotatably attached to the axle 14.

  Here, 21 is a bar handle attached to the upper part of the front fork 13, 22 is a swing arm attached to the lower rear part of the body frame 11, 23 is a rear wheel attached to the rear end of the swing arm 22, 24 is a fuel tank, Reference numeral 25 denotes a sheet.

  FIG. 2 is a front view of a front fork according to the present invention. The front fork 13 includes left and right forks 31 and 32, a top bridge 33 and a bottom bridge 34 that connect the upper portions of the forks 31 and 32, and Each of the top bridge 33 and the bottom bridge 34 includes a steering stem 36 that extends in the vertical direction.

  The fork unit 31 is an inverted type including an outer tube 41 supported by the top bridge 33 and the bottom bridge 33 and an inner tube 42 slidably inserted into the outer tube 41 from below.

The fork unit 32 is an inverted type including an outer tube 44 supported by the top bridge 33 and the bottom bridge 34, and an inner tube 45 slidably inserted into the outer tube 44 from below.
The forks 31 and 32 described above have the same structure, but here, different symbols are used for identification.

The inner tubes 42 and 45 are members that support the axle 14 at the lower end.
The inverted fork units 31 and 32 can be set to have higher bending rigidity than the upright fork unit in which the outer tube is positioned below the inner tube.
The steering stem 36 is a member that is rotatably supported by the head pipe 47.

  FIG. 3 is a front view showing a main part of the front fork (first embodiment) according to the present invention. The outer tubes 41 and 44 are reinforced to improve the bending rigidity of the outer peripheral surfaces 41A and 44A below the bottom bridge 34. This is a member provided with portions 51 and 52, and these reinforcing portions 51 and 52 are portions extending vertically along the respective axes of the outer tubes 41 and 44. The reinforcing part 51 and the reinforcing part 52 have the same shape.

4 is a cross-sectional view taken along line 4-4 of FIG. 3 and shows a cross section of the outer tube 41. FIG. In the figure, FRONT is the front of the vehicle, REAR is the rear of the vehicle, IN is the inner side of the vehicle, and OUT is the outer side of the vehicle (the same applies hereinafter).
The reinforcing portion 51 is formed on the outer circumferential surface 41A of the outer tube 41 on the front-rear direction of the vehicle, that is, the front side and the rear side (that is, the front half constituting the front half of the outer circumferential surface 41A) at an angle of 45 ° from the front-rear direction. 41B and a rear surface 41C constituting the rear half of the outer peripheral surface 41A) are parts provided by welding or bonding a member different from the outer tube 41, and a main body 51a having a constant thickness. This is a portion integrally provided with a peripheral portion 51b provided so that the thickness gradually changes around the main body portion 51a.

  FIG. 5 is a front view showing the main part of the front fork (second embodiment) according to the present invention. The outer tubes 41 and 44 are reinforced to improve the bending rigidity of the outer peripheral surfaces 41A and 44A below the bottom bridge 34. The reinforcing portions 54 and 55 are formed in a substantially right triangle shape so that the circumferential width gradually decreases from the upper part to the lower part, and one side 54a and 55a of the triangle. Are provided along the respective axes of the outer tubes 41 and 44 and at positions in the vehicle front-rear direction, and the other sides 54b and 55b of the triangle are provided so as to extend in the circumferential direction. The reinforcing part 54 and the reinforcing part 55 are symmetrical in shape.

FIG. 6 is a cross-sectional view taken along line 6-6 of FIG.
The reinforcing portion 54 is a range between the position in the vehicle front-rear direction, that is, the front-rear direction and the position at an angle of 45 ° from the vehicle front-rear direction on the outer peripheral surface 41A of the outer tube 41, And the rear side (i.e., the front surface 41B and the back surface 41C), a portion provided by welding or bonding a member different from the outer tube 41, and a body portion 54c having a constant thickness, A peripheral portion 54d provided so as to gradually change the thickness around the main body portion 54c is integrally provided. Specifically, the main body portion 54c is provided in a range from the vehicle front-rear direction on the outer peripheral surface 41A to an angle of 45 °. Part.

FIG. 7 is a graph showing the results of an experiment for confirming the rigidity of the outer tube provided with the reinforcing portion according to the present invention. The vertical axis of the graph represents the rigidity ratio (unit:%), and the horizontal axis represents the direction of the load applied to the front fork (angle, unit: °).
The rigidity ratio is a measurement of the amount of displacement of the load point 111 when a load is applied as shown in FIG. 11 (a), and the amount of displacement of the load point 111 in a standard outer tube without a reinforcing portion is This is expressed as a percentage by dividing by the amount of displacement of the weight point 111 in the measured outer tube.
As a sample of the outer tube, Example 1 (first embodiment shown in FIG. 3), Example 2 (second embodiment shown in FIG. 5), and a reinforcing portion at a position in the vehicle front-rear direction on the outer peripheral surface. It is a comparative example provided.

  In Comparative Example 1, the bending stiffness is slightly higher than that of the standard product when the load direction is 0 °, and the bending stiffness gradually increases substantially linearly as the load direction becomes 30 °, 60 °, and 90 °. It becomes a little lower than the standard product at an angle of 90 °.

  In Example 1, when the load direction is 0 °, the bending stiffness is slightly higher than that of the standard product, and as the load direction approaches 90 °, the decrease rate of the bending stiffness gradually increases, and the bending stiffness at 90 ° is obtained. Is significantly lower than the standard product. That is, the bending rigidity difference between the vehicle front-rear direction and the vehicle width direction is large.

  In Example 2, when the load direction is 0 °, the bending rigidity is slightly higher than that of the standard product, and the bending rigidity in the direction of angle 30 ° to 90 ° is also reduced in substantially the same manner as in Example 1. The bending rigidity at an angle of 90 ° is higher than that in the first embodiment, and the bending rigidity difference between the vehicle longitudinal direction and the vehicle width direction is large as in the first embodiment.

The principle that the rigidity of the outer tube of the outer tube increases in the vehicle front-rear direction and the rigidity in the vehicle width direction decreases due to the reinforcing portion described above will be described in detail with reference to FIGS.
FIGS. 8A and 8B are operation diagrams illustrating the principle of stiffness change depending on the direction of the outer tube of the comparative example.
The outer tube 131 of the comparative example shown in (a) is provided with reinforcing portions 133 and 133 at positions on the outer peripheral surface 132 in the vehicle front-rear direction.
In the outer tube 131, the secondary moments in the direction of the angle 0 ° are increased by the reinforcing portions 133 and 133, and the bending rigidity in the direction of the angle 0 ° is increased.

  In (b), when a load is applied to the front fork from the direction of 90 °, the outer tube 131 is twisted in the direction of the arrow. At this time, since the reinforcing portions 133 and 133 approach the positions in the 90 ° angle direction (points G and H in the figure), the sectional moment in the 90 ° direction increases, and the rigidity in the 90 ° direction is increased. Will grow. Therefore, the difference in bending stiffness between the direction of the angle 0 ° in (a) and the direction of the angle 90 ° in (b) is small.

FIGS. 9A and 9B are operation diagrams illustrating the principle of change in rigidity depending on the direction of the outer tube according to the first embodiment of the present invention.
In (a), in the outer tube 41 of Example 1, since the reinforcement parts 51 and 51 are in the position of 45 degrees from the angle 0 degree direction, the cross-sectional secondary moment of an angle 0 degree direction is the reinforcement parts 51 and 51. Compared to those without, the bending rigidity is also increased.

  In (b), when a load is applied to the front fork from the direction of 90 °, the outer tube 41 is twisted, and the reinforcing portions 51 and 51 move in the direction of 0 °. At this time, since the reinforcing portions 51, 51 are not present in the direction of 90 °, the cross-sectional secondary moment is reduced, and the bending rigidity in the direction of 90 ° is reduced. That is, the difference in bending stiffness between the outer tube 41 at an angle of 0 ° and an angle of 90 ° increases.

FIGS. 10A to 10D are operation diagrams illustrating the principle of change in rigidity depending on the direction of the outer tube according to the second embodiment of the present invention.
In (a), in the outer tube 41 of Example 2, since the upper part of the reinforcement parts 54 and 54 exists in the range between the position of the angle 0 degree direction, and the position of the angle 45 degree from the 0 degree direction, the angle 0 The cross-sectional secondary moment in the ° direction increases, and the bending rigidity also increases.

  In (b), when a load is applied to the front fork from an angle of 90 °, the outer tube 41 is twisted. Since the upper portions of the reinforcing portions 54 and 54 have a large width in the circumferential direction, the twisting angle is smaller than that in the case of FIG. 9B, and the reinforcing portions 54 and 54 move only to the vicinity of the angle 0 ° direction. At this time, since the reinforcing portions 54 and 54 do not exist in the direction of the angle 90 °, the secondary moment of the cross section becomes small, and the bending rigidity in the direction of the angle 90 ° becomes small. That is, the difference in bending stiffness between the outer tube 41 at an angle of 0 ° and an angle of 90 ° increases.

  (C) shows the state of the lower part of the reinforcement parts 54 and 54 at the time of (a). Since the lower part of the reinforcing portions 54 and 54 has a small width in the circumferential direction, the increase in the cross-sectional secondary moment in the direction of angle 0 ° is small and the increase in bending rigidity is also small.

  (D) shows the state of the lower part of the reinforcement parts 54 and 54 at the time of (b). When a load is applied to the front fork 41 from an angle of 90 °, the outer tube 41 is twisted, and the lower portion of the reinforcing portions 54, 54 has a smaller width in the circumferential direction than the upper portion, so that the twist angle becomes larger. At this time, the reinforcing portions 54 and 54 approach the position in the 90 ° angle direction (that is, the points J and K). However, since the width of the reinforcing portions 54 and 54 is small, the increase in the sectional moment in the 90 ° direction is small. Also, the increase in bending rigidity in the direction of 90 ° is small. Accordingly, the rigidity improvement in the direction of 0 ° angle in (c) and the rigidity improvement in the direction of 90 ° angle in (d) are both small.

  As described above with reference to FIGS. 2, 3 and 4, the present invention firstly connects the pair of left and right outer tubes 41, 44 with the top bridge 33 and the bottom bridge 34, and the top bridge 33 and the bottom bridge. An inverted front fork 13 that is supported on the vehicle body frame 11 (see FIG. 1) side by a bridge 34 and supports the front wheel 16 by a pair of left and right inner tubes 42 and 45 that are movably inserted into the lower portions of the outer tubes 41 and 44, respectively. The outer tubes 41, 44 on the outer peripheral surfaces 41A, 44A, on the front surface 41B of the outer tubes 41, 44, at a position closer to the inside of the vehicle body from the front-rear direction of the vehicle, and on the rear surface 41C of the outer tubes 41, 44 The bending rigidity of the outer tubes 41 and 44 is increased at a position close to the outside of the vehicle body from the direction. Characterized in that that the reinforcing portion 51 and 52 respectively.

  The reinforcing portions 51 and 52 can increase the bending rigidity of the outer tubes 41 and 44 in the vehicle front-rear direction, and when a load in the vehicle width direction acts on the front forks 41 and 44 from the front wheel 16 side, the outer tube 41 44 are twisted and the reinforcing portions 51 and 52 approach a direction orthogonal to the load direction, so that the bending rigidity in the vehicle width direction of the outer tubes 41 and 44 at this time can be effectively suppressed.

Secondly, the present invention is characterized in that the reinforcing portions 51 and 52 are provided at a position of an angle of 45 ° from the vehicle longitudinal direction.
When a load in the vehicle width direction is applied to the front forks 41, 44, the reinforcing portions 51, 52 provided at an angle of 45 ° from the vehicle front-rear direction are moved to the vehicle front-rear direction position by twisting the outer tubes 41, 44. Accordingly, it is possible to suppress an increase in bending rigidity of the front forks 41 and 44 in the vehicle width direction.

Thirdly, according to the present invention, as shown in FIGS. 5 and 6, the reinforcing portions 54 and 55 are provided in a range between a position in the vehicle front-rear direction and a position at an angle of 45 ° from the vehicle front-rear direction. It is characterized by.
Since the reinforcing portions 54 and 55 are provided in a range between the position in the vehicle longitudinal direction and the position at an angle of 45 ° from the vehicle longitudinal direction, the circumferential width of the reinforcing portions 54 and 55 can be increased. The bending rigidity of the outer tubes 41, 44 in the vehicle front-rear direction can be further increased while suppressing the increase in bending rigidity of the outer tubes 41, 44 in the vehicle width direction.

Fourthly, the present invention is characterized in that the reinforcing portions 54 and 55 have a cross-sectional area that is smaller at the lower portion than at the upper portion.
Since the cross-sectional area of the reinforcing portions 54 and 55 is made smaller at the lower portion than at the upper portion, for example, the outer tubes 41 and 44 have a smaller width than the upper portion and the lower portion of the reinforcing portions 54 and 55 having the same width. The bending rigidity in the vehicle front-rear direction can be lowered, and thus the cross-sectional areas of the reinforcing portions 54, 55 are made different between the upper portion and the lower portion, so that the outer tubes 41, 42 by the reinforcing portions 54, 55 are front-rear. The direction rigidity can be changed as appropriate.

In the present invention, the reinforcing portion is provided at a position at an angle of 45 ° from the vehicle front-rear direction, or the reinforcing portion is provided in a range between the vehicle front-rear direction and the angle from the vehicle front-rear direction of 45 °. Not limited to this, the angle 45 ° may be appropriately increased or decreased according to the outer diameter, thickness, vehicle weight, and vehicle cornering speed of the outer tube.
In the present embodiment, as shown in FIG. 4, the outer tube 41 and the reinforcing portion 51 are separated from each other. However, the present invention is not limited to this, and the reinforcing portion 51 may be formed integrally with the outer tube 41. .

  The inverted front fork of the present invention is suitable for a two-wheeled vehicle.

1 is a side view of a motorcycle including an inverted front fork according to the present invention. It is a front view of the front fork concerning the present invention. It is a front view which shows the principal part of the front fork (1st Embodiment) which concerns on this invention. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. It is a front view which shows the principal part of the front fork (2nd Embodiment) which concerns on this invention. FIG. 6 is a sectional view taken along line 6-6 of FIG. It is a graph which shows the result of the rigidity confirmation experiment of an outer tube provided with the reinforcement part which concerns on this invention. It is an effect | action figure which shows the principle of the rigidity change by the direction of the outer tube of a comparative example. It is an effect | action figure which shows the principle of the rigidity change by the direction of the outer tube of Example 1 of this invention. It is an effect | action figure which shows the principle of the rigidity change by the direction of the outer tube of Example 2 of this invention. It is explanatory drawing which shows the point which confirms the rigidity of a front fork. It is a 1st explanatory view showing a deformation state when a load is applied to a front fork. It is the 2nd explanatory view showing a deformation state when applying a load to a front fork. It is an effect | action figure explaining the rigidity of the conventional front fork.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Motorcycle, 11 ... Car body (body frame), 13 ... Front fork, 16 ... Front wheel, 33 ... Top bridge, 34 ... Bottom bridge, 41, 44 ... Outer tube, 41A, 44A ... Outer surface of outer tube, 41B ... front surface of outer tube, 41C ... back surface of outer tube, 42, 45 ... inner tube, 51, 52, 54, 55 ... reinforcing portion.

Claims (3)

These top bridge (33) and the bottom bridge with connecting the top bridge a pair of left and right outer tubes (41, 44) (33) and the bottom bridge (34) (34) is supported on the vehicle body (11) side, wherein In an inverted front fork that supports the front wheel (16) with a pair of left and right inner tubes (42, 45) movably inserted in the lower portions of the outer tubes (41, 44) ,
On the outer peripheral surface of the outer tube (41, 44), and wherein the position close to the vehicle body inward from the vehicle longitudinal direction in front of the outer tube (41, 44), at the rear of the outer tube (41, 44) is Reinforcing portions (51, 52) for increasing the rigidity of the outer tubes (41, 44 ) are provided at positions closer to the outside of the vehicle body from the vehicle longitudinal direction,
The reinforcing part (51, 52) is provided at a position at an angle of 45 ° from the vehicle longitudinal direction.
An inverted front fork characterized by that. A pair of left and right outer tubes (41, 44) are connected by a top bridge (33) and a bottom bridge (34) and supported on the vehicle body (11) side by the top bridge (33) and the bottom bridge (34). In an inverted front fork that supports the front wheel (16) with a pair of left and right inner tubes (42, 45) movably inserted in the lower portions of the outer tubes (41, 44),
On the outer peripheral surface of the outer tube (41, 44) and on the front surface of the outer tube (41, 44) at a position close to the vehicle interior from the vehicle front-rear direction, on the rear surface of the outer tube (41, 44). Reinforcing portions (54, 55) for increasing the rigidity of the outer tubes (41, 44) are provided at positions closer to the outside of the vehicle body from the vehicle longitudinal direction,
The reinforcing portion (54, 55) is provided in a range between the vehicle longitudinal direction and an angle of 45 ° from the vehicle longitudinal direction.
  An inverted front fork characterized by that. The inverted front fork according to claim 2, wherein the reinforcing portion (54, 55) has a lower sectional area than an upper portion.

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