JP3279886B2 - Motorcycle cast wheel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle cast wheel in which a hub, a spoke, and a rim are integrally cast.

[0002]

2. Description of the Related Art Conventionally, as a wheel of a motorcycle, there is a cast wheel in which a hub portion, a spoke portion, and a rim portion are integrally cast such that the spoke portion is hollow. In such a cast wheel, it is desired that the cleaning liquid in the pre-coating process can be quickly drained, and that shot balls used in deburring can be quickly discharged.

[0003] In order to ensure the above drainage and the like, there is a spoke formed with a through hole communicating between the inside of the hollow and the outside (see, for example, JP-A-62-74701).

[0004]

By the way, as shown in FIG. 10, the spoke portion 31 is required to improve the drainage performance and the like.
The through hole 32 is formed in the rim-side bottom portion 31a constituting the outer peripheral wall of the hollow b. In such a case, the through hole 32 is connected to the rim portion 33 and the spoke portion 31 by the connecting portion ( Since it is formed on the bottom wall a of the rim, the corner R of the connecting portion a is cut off, and there is a problem that the appearance is deteriorated.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a motorcycle cast wheel that can improve drainage while avoiding deterioration in appearance.

[0006]

According to the first aspect of the present invention, there is provided a hub for inserting an axle, a rim for mounting a tire,
In a cast wheel of a motorcycle, a plurality of spokes extending from the hub and connecting the rim and the hub so as to form a concentric circle are integrally cast so that the spokes are hollow. The rim portion side is closed at the rim side bottom portion, and the inner surface of the rim side bottom portion is located closer to the wheel center than the inner peripheral surface of the bottom wall of the rim portion, and axially penetrates into the hollow from the outside. And the through-hole which is a trace of the core support is located at the corner portion of the rim-side bottommost portion and in contact with the inner surface, and the spoke-portion side wall inner surface has a portion extending from near the outer periphery of the hub portion to near the rim-side bottommost portion. A plurality of grooves extending in the direction in which the spoke portions extend are provided side by side.

According to a second aspect of the present invention, in the first aspect, the lowermost portion on the rim side is deviated from the bottom wall of the rim toward the wheel center, and the inner surface of the lowermost portion on the rim side is the inner peripheral surface of the bottom wall of the rim. The invention is characterized in that it is located closer to the center of the wheel, and the invention according to claim 3 is characterized in that, in claim 2, the lowermost portion on the rim side of the hollow portion has a curved surface convex toward the hub. And

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 are views for explaining a cast wheel of a motorcycle according to an embodiment of the present invention. FIG. 1 is a right side view of a front wheel portion of the motorcycle equipped with the cast wheel of the embodiment, FIG. 2 is a left side view of the cast wheel, and FIG. 3 is a sectional front view (II in FIG. 2).
4 and 5 are enlarged sectional front views of the rim portion, and FIG. 6 is a sectional view of the spoke portion (a sectional view taken along line VI-VI of FIG. 2).

In FIG. 1, reference numeral 1 denotes a front fork rotatably supported left and right by a head pipe 2a at the front end of a vehicle body frame 2. A steering handle 3 is fixed to an upper end of the front fork 1, and is attached to a lower end. Has a front wheel 4 that is rotatably supported. The front wheel 4 includes a cast wheel 5 having the features of the present invention, and a tire 6 mounted on an outer peripheral portion of the wheel 5. The arrow A indicates the direction of rotation during forward movement.

The cast wheel 5 has a hub portion 7 through which an axle is inserted through a bearing, a rim portion 8 on which the tire 6 is mounted, and a concentric circle of the rim portion 8 and the hub portion 7. And three spoke portions 9 connected to the first portion are integrally cast such that the inside of the spoke portions 9 becomes hollow.

The hub portion 7 has an axle support portion 7a at the center, and the axle support portion 7a is surrounded by a thin-walled drum portion 7b. Between the drum portion 7b and the axle support portion 7a, A lightening space a is formed.

The rim portion 8 is formed by integrally forming upright ear portions 8b and 8c on both the left and right sides of a bottom wall 8a having a dish-shaped cross section, into which the tire 6 is fitted. An annular rib 8d for reinforcement is integrally formed on the inner peripheral surface c of the first embodiment.

The spoke portion 9 is inclined in such a manner that an outer peripheral portion thereof is located rearward in the rotational direction in a side view, is slightly arcuate, and has a hollow b inside. The hollow b communicates with the lightening space a of the hub 7, and the rim 8 side is located at the connecting portion between the rim 8 and the spoke 9 of the wall constituting the hollow b. Rim bottom bottom 9
a.

The rim-side bottom portion 9a is offset from the bottom wall 8a of the rim portion 8 toward the wheel center. Thus, the inner surface d of the rim-side bottom portion 9a is located closer to the wheel center than the inner peripheral surface c of the bottom wall 8a of the rim portion 8. Further, the rim-side bottom portion 9a is formed in a slightly arc shape so as to protrude toward the center of the wheel. Further, through holes 9b and 9c are formed in the front corner portion of the rim side bottom portion 9a on the front side in FIG. 2 and on the rear side of the rear corner portion in FIG. These through holes 9b and 9c are formed by traces of a core support piece for forming the hollow b and the lightening space a.

As shown in FIG. 6, each of the three spoke portions 9 has a wing shape when viewed in a cross section, and any of the spoke portions 9 is provided on the inner surface of the side wall 10 constituting the hollow b. 9 also has upper and lower grooves 10a and 10b for reducing the weight by making it thinner than the basic part.
The depth of these grooves is the lower groove 1 located at the bottom during casting.
0b is set deeper than the upper groove 10a located on the upper side. The reason why such a depth is set is as follows.

That is, in order to further reduce the weight, it is only necessary to make the groove deeper and make it thinner. However, if the groove is made too thin, the flow of the molten metal at the time of casting deteriorates, so there is a limit. On the other hand, the pressure of the hot water at the time of casting is higher in the lower portion than in the upper portion due to the weight of the hot water, so that the hot water easily flows to the lower portion. Therefore, in the present embodiment, the lower groove 10b located on the lower side during casting is set deeper to make the lower side thinner, thereby promoting the reduction in weight while ensuring the supply of hot water.

The casting mold for the cast wheel 5 of the present embodiment has a lower portion forming the periphery of the hub portion 7 and the spoke portion 9 and the inner peripheral surface portion of the rim portion 8 as shown by a two-dot chain line in FIG. The mold 21, the upper mold 22, and the left,
It is composed of right dies 23 and 24. In addition, lower mold 2
The upper mold 22 is divided into upper and lower parts by a plane A perpendicular to the axis, and the left mold 23 and the right mold 24 are divided into two parts by a plane B including the axis.

Here, the rim-side bottom portion 9 constituting the hollow b
a is deviated from the bottom wall 8a of the rim portion 8 toward the wheel center, so that the left and right dies 23, 24 for forming the outer peripheral surface of the rim portion may be divided depending on the arrangement position. A so-called undercut occurs, which makes it impossible. In the present embodiment, as shown in FIG. 2, when viewed in the split direction (see arrow C), the parting line B is formed so that a portion that is not caught on the rim-side bottom portion 9 a does not occur, that is, is opened. Since it is set, the rim-side bottom portion 9a does not hinder the mold division.

Next, the operation and effect of the cast wheel 5 will be described. In the present embodiment, the rim-side bottom portion 9a constituting the hollow b is formed into a curved surface slightly convex toward the center of the wheel, and through holes 9b, 9c are formed in the front corner portion and the rear corner portion of the bottom portion 9a. Is formed so as to be in contact with the inner surface d, so that drainage of the cleaning liquid in the hollow b and discharge of shot balls can be secured, and the cleaning liquid or shot balls can be discharged quickly. In addition, since the core support pieces are positioned at the front and rear corners, the through holes 9b and 9c are formed with the traces of the support pieces, so that separate hole processing is not required.

Since the rim-side bottom portion 9a is deflected to the wheel center side from the bottom wall 8a of the rim portion 8, which is a connection point between the rim portion 8 and the spoke portion 9, the through-holes 9b, 9
While c is formed so as to be in contact with the inner surface d of the rim-side bottom portion 9a, the corner R of the connection portion between the rim portion and the spoke portion is not cut off, and it is possible to avoid a reduction in appearance.

Further, since the rim-side bottom portion 9a is deviated toward the center of the wheel, the rim-side bottom portion 9a is separated from the bottom wall 8a of the rim portion 8 when viewed from a casting (material) before machining. The thickness can be reduced, and the weight and cost can be reduced in the material state.

That is, in the case of a cast wheel, as shown in FIGS. 4 and 5, the cast wheel is cast into a shape shown by a two-dot chain line, and the fitting of the rim portion at the portion where the tire is mounted is ensured to reduce air leakage. In order to prevent this and to ensure the thickness of the member required for securing the strength with high accuracy, the workpiece is cut into a shape shown by a solid line. When the conventional bottom portion on the rim side is located at the same position as the bottom wall 8a of the rim portion 8 (see the broken line in FIG. 4), the bottom portion is also machined. Is set to On the other hand, in the case of this embodiment, the rim-side bottom portion 9a is not machined because it is deviated toward the wheel center. Therefore, the rim-side bottom portion 9a is set to a thickness that does not include the processing allowance, and the weight and the useless material are reduced accordingly.

In the casting of the cast wheel 5, it is desirable to cool the spokes 9, the bottom wall 8a, the ears 8b and 8c in order of FIG. However, in the conventional cast wheel, the portion corresponding to the spoke portion of the bottom wall 8a is also thickened by the machining allowance, and has a large heat capacity. Therefore, the ear portions 8b and 8c are placed before the bottom wall 8a. Cooling, after which the bottom wall 8a tends to cool, so that the bottom wall 8a
When hot water is cooled, hot water is not supplied from the surroundings.
a had a problem that sink marks easily occurred. Conventionally, in order to avoid this problem, for example, a feeder for delaying cooling is provided in the ear portion 8c, and this feeder also causes an increase in useless material.

In the case of the present embodiment, as described above, the portion corresponding to the bottom wall 8a of the spoke portion 9, that is, the rim-side bottom portion 9a is as thin as the machining allowance is unnecessary. The bottom 9a cools before the ears 8b, 8c,
The occurrence of sink marks described above is prevented, and as a result, the feeder can be made unnecessary, and in this regard, wasteful materials can be further reduced.

In the above embodiment, the rim-side bottom portion 9
a is formed in a curved surface protruding toward the center of the wheel, but the bottom portion on the rim side does not necessarily have to be formed in a curved surface. For example, as shown in FIG. May be formed.

In the above embodiment, the rim-side bottom portion 9
a is deviated from the bottom wall 8a of the rim portion 8 toward the wheel center, but it is not necessary to deviate, and for example, as shown in FIG. 8, it corresponds to the hollow b of the bottom wall 8a of the rim portion 8. The portion 8a 'to be formed is set to be thick, that is, the lowermost surface f of the hollow b.
May be raised, and a through hole 9e may be formed so as to be in contact with the raised bottom surface 9f.

Further, for example, as shown in FIG.
It is also effective to combine the method of displacing the rim-side lowermost portion and the method of raising the lowermost surface with the position of the spoke portion. In this example, the rim-side bottom surface 4 of the spoke portion 41 located on the split surface B of the left and right dies 23, 24
1a is a bottom-up system, and the rim-side bottom portion 42a of the spoke portion 42 located on a line perpendicular to the split surface B is deviated toward the center of the wheel.

In this case, the spokes 9 are
While having this, there is no trouble in the mold layout,
In any of the spokes, the through hole can be disposed so as to be in contact with the hollow bottom surface and closer to the wheel center than the connection between the spoke portion and the rim portion.

Further, the lowermost rim side bottom surface 41 of the above-mentioned bottom raising system
a, 41a and the rim side bottom 42a, 4 of the offset type
Since the two wheels 2a are located at point-symmetric positions with respect to the wheel center, there is no problem that the weight balance is lost.

[0030]

As described above, according to the motorcycle cast wheel according to the first aspect of the present invention, the innermost surface of the bottom of the spoke hollow rim is closer to the wheel center than the inner peripheral surface of the bottom wall of the rim. And the through hole, which is a trace of the core support, is formed so as to be in contact with the inner surface of the rim-side bottommost portion. Has the effect of improving the drainage properties of the water.

According to the second aspect of the present invention, the portion of the bottom wall of the rim portion corresponding to the bottommost portion on the rim side is deviated from the other portion of the bottom wall toward the wheel center to thereby provide the rim portion. Since the innermost surface of the lowermost portion is located near the center of the wheel, the thickness of the lowermost portion on the rim side at the time of casting can be set to a thin wall that does not require a processing allowance, and weight and cost can be reduced.

According to the third aspect of the present invention, since the lowermost portion of the hollow portion on the rim side is set to a curved surface shape convex toward the hub, there is an effect that the above-described drainage performance can be further improved.

[Brief description of the drawings]

FIG. 1 is a right side view of a motorcycle including a cast wheel according to an embodiment of the present invention.

FIG. 2 is a left side view of the cast wheel of the embodiment.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is an enlarged sectional front view of a rim portion of the cast wheel of the embodiment.

FIG. 5 is an enlarged sectional front view of a rim portion of the cast wheel of the embodiment.

FIG. 6 is a sectional view taken along line VI-VI of FIG. 2;

FIG. 7 is a side view of a modified example of the lowermost portion of the rim portion of the cast wheel of the embodiment.

FIG. 8 is a side view of a modified example of the rim bottom portion of the cast wheel of the embodiment.

FIG. 9 is a side view of a modified example of the cast wheel of the embodiment.

FIG. 10 is a side view of a bottom portion of a rim portion of a conventional cast wheel.

[Explanation of symbols]

 Reference Signs List 5 Cast wheel 6 Tire 7 Hub 8 Rim 8a Bottom wall 9 Spoke 9a Rim side bottom 9b, 9c Through hole b Hollow c Inner peripheral surface d Inner surface

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60B 1/00 B60B 3/00

Claims (3)

(57) [Claims] 1. A hub portion through which an axle is inserted, a rim portion to which a tire is mounted, and a plurality of spoke portions extending from the hub portion and connecting the rim portion and the hub portion so as to form a concentric circle,
In a motorcycle cast wheel in which the spokes are integrally cast so as to form a hollow, the hollow rim portion side is closed at a rim-side lowermost portion, and an inner surface of the rim-side lowermost portion is a rim. position to the wheel center toward the inner circumferential surface of the bottom wall parts
At the same time, a through-hole that is axially penetrated from the outside into the hollow and is a trace of the core support is formed at the bottom of the rim-side corner.
Parts to and is positioned so as to contact the inner surface of the spoke portion
From near the outer periphery of the hub on the inner surface of the side wall to near the bottom of the rim side
A plurality of grooves extending in the extension direction of the spoke part are arranged side by side
Motorcycle casting wheel, characterized in that it has. 2. The rim according to claim 1, wherein the lowermost portion on the rim side is a rim.
A cast wheel for a motorcycle, wherein the inner surface of the rim-side bottommost portion is located closer to the wheel center than the inner peripheral surface of the rim-side bottom wall . 3. The cast wheel according to claim 2, wherein the rim-side bottom portion has a curved surface convex toward the hub.