JP5593251B2 - Fastening structure for steering stem of saddle riding type vehicle - Google Patents

Description

  The present invention relates to a fastening structure for a steering stem of a saddle riding type vehicle.

2. Description of the Related Art Conventionally, as a fastening structure for a steering stem of a saddle-ride type vehicle, there is known a structure in which bearings are provided above and below a head pipe and the steering stem is pivotally supported by these bearings (see, for example, Patent Document 1).
Further, as a steering stem fastening structure similar to Patent Document 1, a structure shown in FIG. 10A is known. In this fastening structure, the lower portion of the steering stem 100 is pivotally supported by the inner race 102A of the lower bearing 102 of the head pipe 101, and the upper portion of the steering stem 100 is pivotally supported by the inner race 103A of the upper bearing 103 of the head pipe 101. The top thread 104 is tightened from above the inner race 103 </ b> A so as to preload the inner race 103 </ b> A, and a stem washer 105 is disposed above the top thread 104. A lock nut 106 is attached to the steering stem 100 from above the stem washer 105. By being fastened, the steering stem 100 is provided on the head pipe 101.
Here, the stem washer 105 is a component that prevents the top thread 104 from rotating together due to friction with the lock nut 106 when the lock nut 106 is tightened. As shown in FIG. It has a locking projection 105A that extends radially inward from its inner periphery. Specifically, a key groove 100A extending in the vertical direction is provided in the steering stem 100 by machining, and the locking projection 105A of the stem washer 105 is engaged with the key groove 100A, so that the stem The washer 105 is prevented from rotating with respect to the steering stem 100. As a result, when the lock nut 106 is tightened, the stem washer 105 is not rotated, and the top thread 104 below is not rotated, so that the top thread 104 is prevented from rotating together.

JP-A-5-170163

By the way, in the above-described conventional structure, the key groove 100A of the steering stem 100 is formed from the upper end of the steering stem 100 to the vicinity of the top thread 104, and the key groove has a length required to prevent the stem washer 105 from rotating. The length of 100A is increased. For this reason, the processing part of the steering stem 100 becomes long, and there is a problem that processing takes time.
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to reduce the number of machining portions of the steering stem and facilitate the machining in the fastening structure of the steering stem of the saddle riding type vehicle.

  In order to achieve the above object, the present invention provides a head pipe (11) provided at a front portion of a vehicle body frame (10), left and right fork pipes (16) for supporting a front wheel at a lower portion, 16) and a fork member having a steering stem (30) provided in the middle of the bridge portion (15) and extending upward and pivotally supported by the head pipe (11). (26), and the steering stem (30) is provided with a groove portion (35) or a chamfered portion (235) along the stem axis, and the lower portion of the steering stem (30) is connected to the head pipe (11). The head pipe is pivotally supported by an inner race (42B) of a bearing (42) provided at the lower portion, and the upper portion of the steering stem (30). 11) The inner race (41B) of the bearing (41) provided at the upper part of the bearing (41) is fitted, and the inner race of the bearing (41) provided at the upper part of the head pipe (11) is fitted into the steering stem (30). A top thread (45) for applying a preload to (41B) is fastened, and is locked to the groove (35) or the chamfered section (235) of the steering stem (30) above the top thread (45). A stem washer (50, 250) having a locking protrusion (56) or a locking surface portion (256) is disposed, and a lock nut (50, 250) is provided on the steering stem (30) from above the stem washer (50, 250). 51) in a steering stem fastening structure of a saddle-ride type vehicle, fastened to the lock nut (51). An outer diameter (I) of the steering stem upper part (34) above the threaded part (33B) is provided smaller than an outer diameter (J) of the screw part (33B), and the stem washer (50, 250) The stem washer (50, 250) passes through the center (O) of the stem washer (50, 250) from the front end (56A, 256A) of the locking projection (56) or the locking surface portion (256). ) Is provided such that the diameter (K) of the circle (Q) whose diameter is a line segment (L1, L3) reaching the inner edge of the steering wheel is larger than the outer diameter (I) of the steering stem upper part (34), An inner diameter (M) of the stem washer (50, 250) is provided to be the same as an outer diameter (J) of the threaded portion (33B) of the steering stem (30), and the steering stem (30) The groove portion (35) or the chamfered portion (235) is provided only in the vicinity of the upper portion of the top thread (45) of the steering stem (30).

  According to this configuration, the outer diameter of the upper portion of the steering stem is provided smaller than the outer diameter of the threaded portion fastened to the lock nut, and the stem washer is fixed from the distal end of the stem washer or the central portion of the engaging surface portion. The diameter of the circle whose diameter is a line segment that reaches the inner edge of the stem washer through the center of the stem is set to be larger than the outer diameter of the upper portion of the steering stem, and the inner diameter of the stem washer is outside the screw portion of the steering stem. Since it is provided to have the same diameter, when fitting the stem washer to the steering stem, it reaches the inner edge of the stem washer through the center of the stem washer from the tip of the stem washer locking projection or the center of the locking surface. A stem washer can be passed through the top of the steering stem along the diameter of a circle whose diameter is a line segment. Therefore, the stem washer can be passed through the steering stem without providing a groove or chamfer on the top of the steering stem, and the groove or chamfer need only be provided near the top thread of the steering stem. The part can be shortened and the number of machining points can be reduced. This facilitates processing and reduces processing costs.

Further, in the above configuration, the protrusion (H) of the locking protrusion (56) or the locking surface portion (256) depends on the outer diameter (I) of the steering stem upper portion (34) and the screw portion (33B). The depth (D, D2) of the groove (35) or the chamfered portion (235) is larger than the size of the step (G). May be formed deeply.
In this case, the protruding amount of the locking protrusion or the locking surface portion is formed larger than the step between the outer diameter of the upper portion of the steering stem and the outer diameter of the screw portion, and the depth of the groove portion or the chamfered portion is the height of the step. Since it is formed deeper than the size, the locking projection or locking surface can be securely locked by deeply engaging the groove or chamfered portion, and the locking projection or locking surface longer than the step is provided. Even if it has a stem washer, it follows the diameter of a circle whose diameter is a line segment that reaches the inner edge of the stem washer through the center of the stem washer from the center end of the stem washer locking protrusion or locking surface. Thus, it is possible to avoid the locking projection or the locking surface portion from coming into contact with the upper portion of the steering stem. As a result, there is no need to provide a groove or chamfered portion at the top of the steering stem, and the number of machining points can be reduced.

  In the fastening structure of the steering stem of the saddle riding type vehicle according to the present invention, when the stem washer is fitted to the steering stem, the stem passes through the center of the stem washer from the front end of the locking washer or the center of the locking surface. The stem washer can be passed through the upper part of the steering stem along the diameter of a circle whose diameter is the line reaching the inner edge of the washer. Therefore, the stem washer can be passed through the steering stem without providing a groove or chamfer on the top of the steering stem, and the groove or chamfer need only be provided near the top thread of the steering stem. The part can be shortened and the number of machining points can be reduced. This facilitates processing and reduces processing costs.

  Further, the locking protrusion or the locking surface portion can be securely engaged by being deeply engaged with the groove portion or the chamfered portion, and the engagement is longer than the step between the outer diameter of the upper portion of the steering stem and the outer diameter of the screw portion. Even when the stem washer has a stop protrusion or a locking surface portion, when the stem washer is fitted to the steering stem, the stem passes through the center of the stem washer from the center of the locking protrusion or the locking surface portion of the stem washer. The stem washer can be passed through the top of the steering stem along the diameter of a circle whose diameter reaches the inner edge of the washer. Therefore, the stem washer can be passed through the steering stem without providing a groove or chamfer on the top of the steering stem. be able to. For this reason, it is only necessary to provide the groove portion or the chamfered portion only in the vicinity of the upper portion of the top thread of the steering stem. Since the groove portion or the chamfered portion can be shortened, the number of machining points can be reduced. As a result, processing becomes easy and processing costs are reduced.

1 is a left side view showing a body frame of a motorcycle to which a steering stem fastening structure for a saddle riding type vehicle according to a first embodiment of the present invention is applied. It is the figure which looked at the vicinity of a head pipe from the vehicle front side. It is an expanded sectional view which shows the fastening structure of a steering stem. It is a top view of a stem washer. It is sectional drawing of the state in which the stem washer is penetrated by the handle post connection part. It is sectional drawing of the state in which the stem washer is penetrated by the thread part. It is a top view of the stem washer of a 2nd embodiment. It is sectional drawing of the state in which the stem washer is penetrated by the handle post connection part. It is sectional drawing of the state in which the stem washer is penetrated by the thread part. It is a figure which shows the fastening structure of the conventional steering stem.

  Hereinafter, a motorcycle according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the up / down, front / rear, and left / right directions are directions seen from the driver of the vehicle.

[First Embodiment]
FIG. 1 is a left side view showing a body frame of a motorcycle to which a steering stem fastening structure for a saddle-ride type vehicle according to a first embodiment of the present invention is applied.
The motorcycle 1 is a straddle-type motorcycle including a vehicle body between a front wheel (not shown) and a rear wheel (not shown). The vehicle body includes a vehicle body frame 10. The vehicle body frame 10 includes a head pipe 11 provided at the front, a main frame 12 extending rearward and rearward from the head pipe 11, a center frame 13 extending downward from the rear of the main frame 12, and a rear from the rear of the main frame 12. The rear frame 14 extends rearward upward.

A steering stem 30 is pivotally supported on the head pipe 11, and a pair of left and right fork pipes 16 are supported at the lower end of the steering stem 30 via a bridge portion 15 extending in the vehicle width direction. The front wheel is pivotally supported on the lower end of the fork pipe 16. A handle post 17 is connected to the upper portion of the steering stem 30, and a handle bar 18 operated by a driver is connected to the handle post 17. By operating the handle bar 18, the steering stem 30 rotates and the front wheels are steered. The
A swing arm (not shown) that can swing up and down is connected to the center frame 13, and the rear wheel is pivotally supported at the rear end of the swing arm.

FIG. 2 is a view of the vicinity of the head pipe 11 as seen from the front side of the vehicle.
The bridge portion 15 includes a stem coupling portion 21 coupled to the lower end of the steering stem 30 and fork coupling portions 22 and 22 that branch from the stem coupling portion 21 to the left and right and extend in the vehicle width direction. The steering stem 30 is integrated with the bridge portion 15 by fitting and welding the lower end of the steering stem 30 to the stem connecting portion 21. Each fork pipe 16, 16 (FIG. 1) is inserted into the fork connecting portion 22 and fixed by split tightening. The steering stem 30, the bridge portion 15, and the fork pipes 16 and 16 constitute a fork member 26 that supports the front wheel.

FIG. 3 is an enlarged cross-sectional view showing a fastening structure of the steering stem 30.
As shown in FIGS. 2 and 3, the fastening structure of the steering stem 30 includes the steering stem 30, the head pipe 11, the bridge portion 15, the upper bearing 41 and the lower bearing 42 that support the steering stem 30 in the vertical direction, and the upper bearing. An upper nut 45 (top thread) fastened to the steering stem 30 above 41, a stem washer 50 that is non-rotatably fitted to the steering stem 30, and a lock fastened to the steering stem 30 above the stem washer 50 A nut 51 is provided.

  The steering stem 30 is a hollow shaft configured to become narrower from the lower end to the upper end, and is accommodated in the head pipe 11 with a lower diameter connecting portion 31 inserted through the stem connecting portion 21 and a smaller diameter than the lower end connecting portion 31. The extension portion 32, the bearing connection portion 33 connected to the upper bearing 41 with a smaller diameter than the extension portion 32, and the handle post connection portion 34 (smaller than the bearing connection portion 33 and extending to the upper end of the steering stem 30) Top). A handle post 17 (FIG. 1) is connected to the upper portion of the handle post connecting portion 34.

The bearing connecting portion 33 includes a fitting portion 33A into which the upper bearing 41 is fitted, and a screw portion 33B that is formed continuously upward from the fitting portion 33A. The threaded portion 33B is formed by screwing an outer peripheral surface having the same diameter as the fitting portion 33A, and an upper nut 45 and a lock nut 51 are fastened to the threaded portion 33B.
A groove portion 35 extending along the stem axis of the steering stem 30 is formed on the outer peripheral surface of the lower portion of the screw portion 33 </ b> B and the handle post coupling portion 34. The groove part 35 is formed by being cut by machining.

  The stem washer 50 is formed in a ring shape and is interposed between the upper nut 45 and the lock nut 51. The stem washer 50 has a locking projection 56 (see FIGS. 3 and 4) that protrudes radially inward from the inner periphery thereof, and the locking projection 56 engages with the groove 35 of the steering stem 30. Thus, the stem washer 50 is locked to the steering stem 30 and cannot rotate. That is, since the stem washer 50 is not rotatable with respect to the steering stem 30 and the lock washer 51 is tightened, the stem washer 50 does not rotate, so that the upper nut 45 contacting the lower surface of the stem washer 50 rotates together with the lock nut 51. Is prevented. In addition, a ring-shaped dust cover 47 is provided on the lower surface of the upper nut 45 to cover the upper side of the bearing housing portion 24.

  The upper bearing 41 and the lower bearing 42 are ball bearings. The outer races 41A and 42A are press-fitted into the head pipe 11, the inner races 41B and 42B into which the steering stem 30 is fitted, the outer races 41A and 42A, and the inner races. And balls 41C, 42C provided between the races 41B, 42B.

  The head pipe 11 is formed in a vertically extending circular tube shape, and bearing housing portions 24 and 25 formed by expanding the outer diameter and inner diameter of the head pipe 11 are provided at the upper end and the lower end. The upper bearing housing portion 24 has an inner surface portion 24A into which the outer race 41A of the upper bearing 41 is press-fitted, and a bottom portion 24B that receives the outer race 41A in the axial direction. The lower bearing housing portion 25 has an inner surface portion 25A into which the outer race 42A of the lower bearing 42 is press-fitted, and a bottom portion 25B that receives the outer race 42A in the axial direction.

The stem connecting portion 21 of the bridge portion 15 has a flat surface portion 21A radially inward of the inner surface portion 25A of the bearing housing portion 25, and the flat surface portion 21A contacts the lower surface of the inner race 42B.
The upper bearing 41 is accommodated in the bearing accommodating portion 24 with the upper portion of the inner race 41B protruding from the upper end of the head pipe 11, and in this state, the upper nut 45 is fastened to the screw portion 33B of the steering stem 30, The upper surface of the inner race 41B is pressed. Further, a lock nut 51 is fastened above the upper nut 45, and a stem washer 50 is interposed between the upper nut 45 and the lock nut 51.
Specifically, due to the fastening force of the upper nut 45, the inner race 41 </ b> B is pressed toward the outer race 41 </ b> A on the upper side of the head pipe 11, and the stem connecting portion 21 is pulled upward on the lower side, so The inner race 42B is pressed toward the outer race 42A by the portion 21A. That is, the steering stem 30 is rotatably supported by the head pipe 11 by sandwiching the upper bearing 41 and the lower bearing 42 from above and below by the upper nut 45 and the bridge portion 15.

Further, when the upper nut 45 is tightened, in the upper bearing 41 and the lower bearing 42, pressure is generated that the inner races 41B and 42B press the balls 41C and 42C toward the outer races 41A and 42A. Then, this pressure is called preload. Since this preload varies depending on the tightening torque of the upper nut 45 and affects the operability of the upper bearing 41 and the lower bearing 42, the upper nut 45 needs to be fastened with an appropriate tightening torque.
In the first embodiment, the stem washer 50 is provided to prevent the upper nut 45 from rotating together by fastening the lock nut 51, and the tightening torque of the upper nut 45 once properly tightened can be reduced. Therefore, the operability of the upper bearing 41 and the lower bearing 42 can be improved.

FIG. 4 is a plan view of the stem washer 50.
The stem washer 50 is a plate formed in a circular ring shape, and has a ring-shaped washer main body 52. The washer main body 52 has an outer diameter portion 52A, an inner diameter portion 52B, and a locking protrusion. Part 56. The inner diameter part 52 </ b> B has a perfect circle part 62 occupying most of the inner diameter part 52 </ b> B, and a curved surface part 63 having a different curvature radius from the perfect circle part 62.
The locking protrusion 56 is a substantially rectangular protrusion in plan view, and protrudes from the perfect circle part 62 of the inner diameter part 52B toward the center O of the outer diameter part 52A. An extension line L obtained by extending the center line in the width direction of the locking projection 56 passes through the center O. Further, a curved corner 57 that is recessed toward the outer diameter portion 52 </ b> A is formed on the side of the base end of the locking protrusion 56.
In FIG. 4, the reference circle P of the perfect circle portion 62 of the inner diameter portion 52B is indicated by a one-dot chain line, and the reference circle Q of the curved surface portion 63 is indicated by a two-dot chain line. The reference circle P and the reference circle Q are true circles.

  The outer diameter portion 52A and the reference circle P of the perfect circle portion 62 are in a coaxial positional relationship, and the outer diameter portion 52A and the center O of the reference circle P coincide. The inner diameter portion 52B is a portion through which the screw portion 33B of the steering stem 30 is inserted, and the diameter M (FIG. 4) of the reference circle P (true circle portion 62) is a screw so that the screw portion 33B can be inserted. It is formed substantially the same as the diameter J (FIG. 5) of the outer diameter portion 36 of the portion 33B.

The diameter K (FIG. 4) of the reference circle Q of the curved surface portion 63 is the diameter I (FIG. 5) of the outer diameter portion 37 of the handle post connecting portion 34 so that the handle post connecting portion 34 can pass through the reference circle Q. It is formed slightly larger than. The diameter K of the reference circle Q is smaller than the diameter M of the reference circle P.
The reference circle Q is arranged such that the center O1 of the reference circle Q is located on the extension line L and the center tip 56A of the locking projection 56 is circumscribed by the reference circle Q. When the reference circle Q is arranged in this way, a part of the reference circle Q is located on the outer diameter portion 52A side of the reference circle P in the portion facing the locking projection 56 in the inner diameter portion 52B, and two intersection points X, X will intersect. In the first embodiment, the portion of the reference circle Q located outside the intersections X and X is the curved surface portion 63. That is, the inner diameter portion 52B is configured by the reference circle P corresponding to the diameter J of the screw portion 33B at the portion closer to the locking projection 56 than the intersections X and X, and the remaining portion is the diameter of the handle post connecting portion 34. It consists of a reference circle Q corresponding to I.

  In other words, the reference circle Q having a diameter of a line segment L1 that reaches the inner edge of the stem washer 50 from the center tip 56A of the locking projection 56 of the stem washer 50 through the center O of the stem washer 50. The diameter K is provided to be larger than the diameter I of the handle post coupling portion 34 of the steering stem 30. The center O1 of the reference circle Q is arranged offset to the opposite side of the locking projection 56 with respect to the center O of the outer diameter portion 52A.

FIG. 5 is a cross-sectional view of the state in which the stem washer 50 is inserted through the handle post connecting portion 34.
When the stem washer 50 is attached to the steering stem 30, the stem washer 50 is inserted from the handle post connecting portion 34 side and moves downward. In the middle stage of attachment, the curved portion 63 of the inner diameter portion 52B is attached to the handle portion as shown in FIG. It moves along the post connecting part 34.
As shown in FIG. 5, the outer diameter portion 36 of the bearing coupling portion 33 including the screw portion 33B and the outer diameter portion 37 of the handle post coupling portion 34 are provided in a coaxial positional relationship. A step G is formed between the diameter portion 37 and the entire circumference. Further, the depth D of the groove 35 with respect to the outer diameter portion 36 of the bearing coupling portion 33 is formed to be larger than the size of the step G. That is, the groove part 35 is also formed in the outer diameter part 37 of the handle post coupling part 34, and the bottom part of the groove part 35 is located on the inner side in the radial direction than the outer diameter part 37.

  The protrusion H in the radial direction of the locking projection 56 when the reference circle P is used as a reference is formed to be larger than the step G of the steering stem 30, and the locking projection 56 corresponds to the handle post connecting portion 34. It is possible to enter the groove portion 35 to the inside in the radial direction from the outer diameter portion 37.

FIG. 6 is a cross-sectional view of the state in which the stem washer 50 is inserted through the threaded portion 33B.
As shown in FIG. 6, in a state where the stem washer 50 is set on the upper surface of the upper nut 45 (FIG. 3), the perfect circle portion 62 of the inner diameter portion 52 </ b> B fits into the screw portion 33 </ b> B of the steering stem 30. And the center of the threaded portion 33B substantially coincide with each other. In this state, there is a gap between the curved surface portion 63 and the outer diameter portion 36 of the screw portion 33B. However, the screw portion 33B is in contact with the perfect circle portion 62 on the intersection X and X side of the center O and guides. And is positioned at an appropriate position. For this reason, the locking protrusion 56 engaged with the groove 35 does not come off from the groove 35 and can be reliably prevented from rotating. Further, since the locking projection 56 engages in the groove 35 deeper than the step G of the steering stem 30, the stem washer 50 can be firmly locked to the steering stem 30 and can be reliably prevented from rotating.

Next, a procedure for assembling the steering stem 30 to the head pipe 11 will be described.
First, as shown in FIG. 2, a lower bearing 42 is provided in the head pipe 11, and a steering stem 30 provided integrally with the bridge portion 15 is inserted into the head pipe 11 from below the head pipe 11, thereby 41 is provided on the head pipe 11, and the upper nut 45 is temporarily fastened to the threaded portion 33 </ b> B of the steering stem 30. Grease is applied to the upper bearing 41 and the lower bearing 42.

Next, while supporting the bridge portion 15, the upper nut 45 is tightened with a predetermined torque, and then the steering stem 30 is rotated several times to allow the upper bearing 41 and the lower bearing 42 to become familiar. Next, the upper nut 45 is once loosened until the tightening torque becomes zero, and then the upper nut 45 is fastened with a predetermined torque.
Then, the stem washer 50 is set so that the locking projection 56 fits into the groove portion 35 and placed on the upper nut 45, and then the lock nut 51 is fastened to the screw portion 33B. Assembly is complete.

Here, the assembly of the stem washer 50 to the steering stem 30 will be described in detail.
The stem washer 50 is passed from the upper end of the steering stem 30 to the handle post connecting portion 34 and is inserted downward to the upper nut 45 side. As shown in FIG. 5, the stem washer 50 has an orientation in which the locking projection 56 is positioned above the groove portion 35 of the steering stem 30, and the curved surface portion 63 of the inner diameter portion 52 </ b> B is the outer diameter of the handle post coupling portion 34. It is moved to the upper nut 45 side in contact with the portion 37. In this state, when the curved surface portion 63 abuts on the outer diameter portion 37, the stem washer 50 is offset entirely from the center O of the handle post coupling portion 34, and on the opposite side of the curved surface portion 63. The stop projection 56 is separated from the outer diameter portion 37.

As a result, even when the protrusion amount H of the locking projection 56 is larger than the step G of the steering stem 30, the locking projection 56 is brought into contact with the outer diameter portion 37 of the handle post connecting portion 34 when the stem washer 50 is inserted. Since contact can be avoided, there is no need to form the groove 35 in the handle post connecting portion 34, and the processing length of the groove 35 can be shortened. In the first embodiment, as shown in FIG. 3, the groove 35 is formed in a section from the vicinity of the upper surface of the upper bearing 41 to the upper portion of the lock nut 51, and is formed only in the vicinity of the upper portion of the upper nut 45. Therefore, compared with the case where the key groove 100A is formed up to the upper end of the steering stem 100 as shown in FIG.
Further, in a state where the stem washer 50 is inserted through the threaded portion 33B, the stem washer 50 is guided by being brought into contact with the perfect circle portion 62 on the intersection X and X side from the center O, and is positioned at an appropriate position. Even if the curved surface portion 63 is provided, the stem washer 50 can be positioned at an appropriate position.

Moreover, since the groove part 35 should just be provided in the upper vicinity of the upper nut 45, the freedom degree of the position which arrange | positions the groove part 35 improves.
Furthermore, since the groove portion 35 is not formed at the upper end of the steering stem 30, water or the like can hardly enter the upper nut 45 side along the groove portion 35 from the upper end of the steering stem 30.

  As described above, according to the first embodiment to which the present invention is applied, the diameter I of the outer diameter portion 37 of the handle post coupling portion 34 at the upper portion of the steering stem 30 is the screw fastened to the lock nut 51. It is provided smaller than the diameter J of the outer diameter portion 36 of the portion 33B, and reaches the inner diameter portion 52B of the stem washer 50 from the center end 56A of the locking projection 56 of the stem washer 50 through the center O of the stem washer 50. The diameter K of the reference circle Q whose diameter is the line segment L1 is provided so as to be larger than the diameter I of the outer diameter portion 37 of the handle post coupling portion 34, and the round portion 62 of the inner diameter portion 52B of the stem washer 50 is provided. Since the diameter M is provided so as to be the same as the diameter J of the screw portion 33B of the steering stem 30, when the stem washer 50 is fitted to the steering stem 30, the center end of the locking projection 56 is provided. The stem washer 50 is passed through the handle post connecting portion 34 along the curved surface portion 63 of the reference circle Q whose diameter is a line segment L1 reaching the inner diameter portion 52B of the stem washer 50 from the center 56A through the center O of the stem washer 50. Can do. For this reason, the stem washer 50 can be passed through the handle post connecting portion 34 without providing the groove portion 35 in the handle post connecting portion 34, and the groove portion 35 of the steering stem 30 may be provided only in the vicinity of the upper portion of the upper nut 45. Therefore, the groove part 35 can be shortened and a processing part can be decreased. For this reason, processing becomes easy and processing costs can be reduced.

  Further, the protrusion amount H of the locking protrusion 56 is formed larger than the step G between the outer diameter portion 37 of the handle post coupling portion 34 and the outer diameter portion 36 of the screw portion 33B, and the depth D of the groove portion 35 is formed. Is formed deeper than the size of the step G, so that the locking projection 56 can be securely engaged by deeply engaging the groove 35 and the stem washer 50 having the locking projection 56 longer than the step G can be secured. Even so, along the curved surface portion 63 of the reference circle Q whose diameter is a line segment L1 that reaches the inner diameter portion 52B of the stem washer 50 from the center tip 56A of the locking projection 56 through the center O of the stem washer 50. By making it, it can avoid that the latching protrusion 56 contacts the outer diameter part 37 of the handle post coupling part 34. As a result, it is not necessary to form the groove 35 in the entire axial direction of the handle post connecting portion 34, so that the processing portion of the groove 35 can be shortened.

[Second Embodiment]
Hereinafter, a second embodiment to which the present invention is applied will be described with reference to FIGS. In the second embodiment, parts that are configured in the same manner as in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.
In the first embodiment, the locking projection 56 of the stem washer 50 is described as engaging with the groove 35. However, in the second embodiment, the locking surface portion 256 of the stem washer 250 is the steering stem. The point which is engaged with 30 chamfered portions 235 is different from the first embodiment.

FIG. 7 is a plan view of the stem washer 250 according to the second embodiment.
The stem washer 250 is a plate material formed in a circular ring shape, and has a washer body 52. The washer body 52 has an outer diameter portion 52A and an inner diameter portion 252B. The inner diameter portion 252B has a perfect circle portion 62, a curved surface portion 63, and a locking surface portion 256 formed linearly in plan view. ing.

In FIG. 7, the reference circle P of the perfect circle portion 62 of the inner diameter portion 252B is indicated by a one-dot chain line, and the reference circle Q of the curved surface portion 63 is indicated by a two-dot chain line. The reference circle P and the reference circle Q are true circles.
The locking surface portion 256 is a flat surface portion formed so as to linearly chamfer a part of the outer periphery of the reference circle P in plan view. An extension line L2 obtained by extending a straight line orthogonal to the central portion in the longitudinal direction of the locking surface portion 256 passes through the center O of the outer diameter portion 52A.

  The reference circle Q is arranged at a position where the center O1 of the reference circle Q is located on the extension line L2 and the center end 256A of the locking surface portion 256 circumscribes the reference circle Q. When the reference circle Q is arranged in this manner, a part of the reference circle Q is located on the outer diameter portion 52A side of the reference circle P in the portion facing the locking surface portion 256 in the inner diameter portion 252B, and the two intersections X , X. In the second embodiment, the portion of the reference circle Q located outside the intersections X and X is the curved surface portion 63. That is, the inner diameter portion 252B is configured by a reference circle P corresponding to the diameter J of the screw portion 33B at the portion closer to the locking surface portion 256 than the intersections X and X, and the remaining portion is the diameter I of the handle post connecting portion 34. The reference circle Q and the locking surface portion 256 are provided.

  In other words, the diameter of the reference circle Q whose diameter is the size of the line segment L3 that reaches the inner edge of the stem washer 250 from the center end 256A of the locking face portion 256 of the stem washer 250 through the center O of the stem washer 250. K is provided to be larger than the diameter I of the handle post connecting portion 34 of the steering stem 30.

FIG. 8 is a cross-sectional view showing a state where the stem washer 250 is inserted through the handle post connecting portion 34.
As shown in FIG. 8, a flat chamfered portion 235 formed by chamfering the outer diameter portion 36 and the lower portion of the outer diameter portion 37 by machining is provided below the screw portion 33B and the handle post connecting portion 34. ing. The chamfered portion 235 is formed in a shape corresponding to the locking surface portion 256 of the stem washer 250, and the stem washer 250 is prevented from rotating by locking the locking surface portion 256 to the chamfered portion 235.
A radial depth D2 of the chamfered portion 235 with respect to the outer diameter portion 36 of the bearing coupling portion 33 is formed larger than the size of the step G. That is, the chamfered portion 235 is also formed on the outer diameter portion 37 of the handle post coupling portion 34, and the bottom portion of the chamfered portion 235 is located on the inner side in the radial direction than the outer diameter portion 37.

  When the reference circle P is used as a reference, the protruding amount H2 in the radial direction of the locking surface portion 256 is formed larger than the step G, and the locking surface portion 256 is larger than the outer diameter portion 37 of the handle post connecting portion 34. It is possible to enter the chamfered portion 235 to the inside in the radial direction.

FIG. 9 is a cross-sectional view of the state in which the stem washer 250 is inserted through the threaded portion 33B.
As shown in FIG. 9, in the state where the stem washer 250 is set on the upper surface of the upper nut 45 (FIG. 3), there is a gap between the curved surface portion 63 and the outer diameter portion 36 of the screw portion 33B. The portion 33B is guided in contact with the perfect circle portion 62 on the side of the intersection X and X with respect to the center O, and is positioned at an appropriate position. For this reason, the locking surface portion 256 engaged with the chamfered portion 235 does not come off from the chamfered portion 235 and can be reliably prevented from rotating. Further, since the locking surface portion 256 engages in the chamfered portion 235 deeper than the step G of the steering stem 30, the stem washer 250 can be firmly locked to the steering stem 30 and can be reliably prevented from rotating.

  According to the second embodiment to which the present invention is applied, the diameter I of the outer diameter portion 37 of the handle post coupling portion 34 at the upper portion of the steering stem 30 is the outer diameter portion of the screw portion 33B fastened to the lock nut 51. 36, the line segment L3 reaching the inner diameter portion 252B of the stem washer 250 from the center end 256A of the locking surface portion 256 of the stem washer 250 through the center O of the stem washer 250 is defined as the diameter. The diameter K of the reference circle Q is provided so as to be larger than the diameter I of the outer diameter portion 37 of the handle post coupling portion 34, and the diameter M of the perfect circle portion 62 of the inner diameter portion 252 </ b> B of the stem washer 250 is Since it is provided so as to be the same as the diameter J of the threaded portion 33B, when the stem washer 250 is fitted to the steering stem 30, the line segment L3 is a reference. Along a curved surface portion 63 of the Q can be passed through the stem washer 250 to the handle post connecting section 34. Therefore, the stem washer 250 can be passed through the handle post connecting portion 34 without providing the handle post connecting portion 34 with the chamfered portion 235, and the chamfered portion 235 of the steering stem 30 is provided only near the upper portion of the upper nut 45. Therefore, the chamfered portion 235 can be shortened, and the number of machining points can be reduced. For this reason, processing becomes easy and processing costs can be reduced.

  Further, the protrusion amount H2 of the locking surface portion 256 is formed larger than the step G between the outer diameter portion 37 of the handle post coupling portion 34 and the outer diameter portion 36 of the screw portion 33B, and the depth D2 of the chamfered portion 235 is formed. Is formed deeper than the size of the step G, so that the locking face portion 256 can be securely engaged by deeply engaging the chamfered portion 235 and the stem washer 250 having the locking surface portion 256 longer than the step G. Even so, it follows the curved surface portion 63 of the reference circle Q whose diameter is a line segment L3 that reaches the inner diameter portion 252B of the stem washer 250 from the center tip 256A of the locking surface portion 256A through the center O of the stem washer 250. Thus, it is possible to avoid the locking surface portion 256 from coming into contact with the outer diameter portion 37 of the handle post connecting portion 34. As a result, it is not necessary to form the chamfered portion 235 in the entire axial direction of the handle post connecting portion 34, so that the machining portion of the chamfered portion 235 can be shortened.

1 Motorcycle (saddle-ride type vehicle)
DESCRIPTION OF SYMBOLS 10 Body frame 11 Head pipe 15 Bridge part 16 Fork pipe 26 Fork member 30 Steering stem 33A Fitting part 33B Screw part 34 Handle post connection part (steering stem upper part)
35 Groove 41 Upper bearing (bearing provided at the top)
41B Inner race (Bearing inner race provided on top)
42 Lower bearing (bearing provided at the bottom)
42B Inner race (Bearing inner race provided at the bottom)
45 Upper nut (Top thread)
50, 250 Stem washer 51 Lock nut 56 Locking projection 56A, 256A Center end 235 Chamfered portion 256 Locking surface D, D2 Depth G Step H Projecting amount I Diameter (outer diameter of steering stem upper part)
J diameter (external diameter of thread)
K diameter (diameter of a circle with the diameter reaching the inner edge of the stem washer)
L1, L3 line segment (line segment reaching the inner edge of the stem washer)
M diameter (inner diameter of stem washer)
O center (center of stem washer)
Q reference circle (circle with diameter reaching the inner edge of the stem washer)

Claims (2)

A head pipe (11) provided at a front portion of the vehicle body frame (10), left and right fork pipes (16) pivotally supporting a front wheel at a lower portion, a bridge portion (15) connecting the left and right fork pipes (16), And a fork member (26) provided in the middle of the bridge portion (15) and extending upward and pivotally supported by the head pipe (11). 30) is provided with a groove (35) or a chamfered portion (235) along the stem axis, and the lower portion of the steering stem (30) is an inner race of a bearing (42) provided at the lower portion of the head pipe (11). (42B) is supported on the steering stem (30) at the top of the head pipe (11). The inner race (41B) of (41) is fitted, and the top that preloads the inner race (41B) of the bearing (41) provided on the upper portion of the head pipe (11) on the steering stem (30). A locking protrusion (56) or a locking protrusion (56) that is locked to the groove (35) or the chamfered portion (235) of the steering stem (30) above the top thread (45). A stem washer (50, 250) having a locking surface portion (256) is arranged, and the steering stem (30) is a straddle to which a lock nut (51) is fastened from above the stem washer (50, 250). In the fastening structure of the steering stem of a type vehicle,
The outer diameter (I) of the steering stem upper part (34) above the screw part (33B) fastened to the lock nut (51) is provided smaller than the outer diameter (J) of the screw part (33B). ,
The center (O) of the stem washer (50, 250) is formed from the front end (56A, 256A) of the locking projection (56) or the locking surface portion (256) of the stem washer (50, 250). The diameter (K) of a circle (Q) whose diameter is a line segment (L1, L3) that passes through and reaches the inner edge of the stem washer (50, 250) is the outer diameter (I) of the steering stem upper part (34). Is provided to be larger than
An inner diameter (M) of the stem washer (50, 250) is provided to be the same as an outer diameter (J) of the screw portion (33B) of the steering stem (30), and the steering stem (30) A fastening structure for a steering stem of a straddle-type vehicle, wherein the groove portion (35) or the chamfered portion (235) is provided only near the upper portion of the top thread (45) of the steering stem (30).   The protrusion amount (H) of the locking protrusion (56) or the locking surface portion (256) is determined by the outer diameter (I) of the steering stem upper portion (34) and the outer diameter (J) of the screw portion (33B). The depth (D, D2) of the groove (35) or the chamfered portion (235) is formed deeper than the size of the step (G). The fastening structure of the steering stem of the saddle riding type vehicle according to claim 1.

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