JP2566696B2 - Casting wheels for motorcycles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spoke portion, a hub portion,
The present invention also relates to a cast wheel integrally cast with a rim portion, and more particularly to an improvement in the cross-sectional shape of the spoke portion, which allows the spoke portion to be lightweight and highly rigid, and is advantageous in terms of air resistance during rotation and appearance.

[0002]

2. Description of the Related Art As a wheel used for a motorcycle or the like, there is a so-called cast wheel in which a spoke portion is integrally cast with a hub portion and a rim portion. In this type of wheel, it is important to secure necessary rigidity and to reduce the weight as much as possible. Since a large load such as a driving force and a braking force acts on the wheels in the rotation direction, it is important to secure the rigidity in the rotation direction. From this point of view, the spoke portion is formed to have a substantially H-shaped cross section, and both lateral ribs of the spoke portion are positioned at the front and rear in the rotational direction, or the spoke portion is formed to have a cross-shaped cross section ( For example, see Japanese Utility Model Publication No. 51-14401). Particularly, in the case of the wheel having the conventional structure having the H cross section, since the spoke portion has a shape having high rigidity in the rotation direction, it is possible to reduce the weight while ensuring the necessary rigidity.

[0003]

By the way, in the case of the wheel having the H-shaped spokes, it is advantageous to increase the width of the lateral ribs in order to improve the rigidity, but the ribs are lengthened. There is a problem that the air resistance during rotation increases. Further, in the case of a structure having an H-shaped or cross-shaped cross section, there is a problem that mud or the like is likely to be clogged between the front and rear lateral ribs or the front surface of the lateral rib, and the appearance is likely to be deteriorated.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to provide a cast wheel which is lightweight and has high rigidity, rotational air resistance, and an advantageous appearance.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a hub portion, a rim portion, and a plurality of spoke portions provided between the hub portion and the rim portion at intervals in the rotational direction. In a cast wheel for a two-wheeled vehicle integrally cast into a hollow structure having a hollow portion inside and a hollow portion inside the hub portion, the cross-sectional shape of the spoke portion is defined by the length in the rotational direction (longitudinal length). a) is longer than the axial length (width b)
It has a substantially elliptical airfoil , and its front-rear length a is close to the rim.
The hollow portion is formed so as to be longer and shorter as it is closer to the hub portion, the outer end opening of the hollow portion is closed by the bottom wall of the rim portion, and the hollow portion and the lightening portion of the hub portion are communicated with each other. A through hole and an opening corresponding to the core holding portion for integrally holding the core and the core for forming the lightening portion in the mold are formed in the spoke portion and the hub portion, respectively. It is characterized in that the side wall of the spoke portion is formed at a portion facing the axial direction and close to the rim portion to have a small diameter for communicating the hollow portion with the outside.

[0006]

According to the cast wheel of the present invention, when the spoke portion is viewed in cross section, the wing shape of a substantially elliptical shape in which the length in the rotation direction (front-rear length a) is longer than the length in the axial direction (width b). Because,
With the same thickness and circumference, the rigidity in the rotational direction can be greatly improved. Therefore, if the required rigidity is the same, the weight can be significantly reduced. In addition, the above-mentioned spokes have a wing shape.
When you do, the front-rear length a becomes longer toward the hub as it gets closer to the rim.
The shorter the distance, the shorter the length of the adjacent outer surface of the hub.
The surface area between the pork portions can be increased and the outer peripheral surface
The degree of freedom of opening position can be increased when forming an opening
With this, the opening can be enlarged, and from this point as well
The weight can be reduced. Also, this opening is
It will be an opening for discharging core sand.
Since the opening can be enlarged like this, the sand can be easily discharged.
Wear. Further, in the present invention, the hollow portion and the lightening portion of the hub portion are communicated with each other, a through hole is formed on the rim portion side of the spoke portion, and an opening for communicating the lightening portion with the outside is formed on the hub portion. Therefore, since the cores for forming the hollow portion and the lightening portion can be integrated with each other, the strength of the entire core can be improved, and by utilizing the through hole, the integral core By utilizing the opening at the tip portion, the core portions for forming the lightening portion of the integral core can be reliably positioned and supported. As a result, deformation and displacement of the core during pouring are prevented and casting accuracy is improved. Further, since the outer end opening of the hollow portion is closed by the rim portion, the connection strength between the hollow portion and the rim portion is improved. Furthermore, in the present invention, since the through hole is formed in a portion of the side wall of the spoke portion facing the axle direction near the rim portion, the rigidity of the wheel in the rotation direction does not decrease, and the dynamic pressure during traveling is reduced. Since it is hard to receive and the centrifugal force acts, the water accumulated inside the spokes is easily discharged.

Since the spokes are set so that the axial length of the wheel is shorter than the rotational length, that is, the axial thickness is thin, the air resistance during rotation can be reduced. Further, as compared with the H-shaped and cruciform cross-sections described above, mud and the like are less likely to adhere and can be easily washed off, which is advantageous in appearance.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to 6 are views for explaining a cast wheel according to an embodiment of the present invention, FIG. 1 is a side view thereof, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. III arrow view, FIGS. 4 and 5 are IV-IV line sectional views and VV line sectional views of FIG. 1, and FIG. 6 is a side view of the front part of the motorcycle equipped with the embodiment wheels.

In FIG. 6 showing the front part of the motorcycle, 1
Is a vehicle body frame, and a steering shaft 2 of a front fork 3 is supported by a head pipe 1a fixed to the front end of the frame 1 so as to be rotatable left and right. A front wheel 4 is pivotally supported on the lower end of the front fork 3. The front wheel 4 is composed of a cast wheel 5 according to the present embodiment and a tire 6 mounted on the outer circumference thereof.

1 to 5 showing the casting wheel 5, the arrow A indicates the direction of rotation of the casting wheel 5. The cast wheel 5 further includes a hub portion 7 located at the center of rotation, a rim portion 9 located on the outer periphery and serving as a mounting portion for the tire 6, and a radial portion extending from the hub portion 7, and the hub portion 7 and the rim. It is composed of three spoke portions 8 that integrally connect the portion 9 and is integrally formed by casting. The number of spokes 8 is not limited to three, and a plurality of spokes 8 may be provided.

The hub portion 7 has a tubular axle support portion 10 at the center and has a double tubular shape in which the outer side is surrounded by a thin wall portion 7a, and the wheel support portion 10 and the thin wall portion 7 are formed. The enclosed space is the lightening portion 11. An opening 12 as shown in FIG. 3 is formed in each area portion (three places in total) sandwiched by two spoke portions 8, 8 adjacent to each other on the outer peripheral surface of the thin portion 7a.

The spokes 8 are formed so as to have a slight inclination angle on the side opposite to the rotational direction with respect to the radial direction. As a result, the spokes 8 are formed on the thin portion 7a of the hub 7. It is almost tangential to it.

The inside of the spoke portion 8 is a hollow portion 13 surrounded by a thin portion 8a having a substantially uniform thickness. As shown in FIGS. 4 and 5, the cross-sectional shape of the spoke portion 8 is an elliptical shape in which the length in the rotational direction (front-rear length) a is longer than the length in the axial direction (horizontal width) b. The opposite part is flatter, resulting in an airfoil. Moreover, the front-rear length a of this cross-sectional shape is longer as it is closer to the rim portion 9 (see FIG. 4) and shorter as it is closer to the hub portion 7 (see FIG. 5), and conversely, the lateral width b is
The rim portion 9 is narrower (see FIG. 4) and the hub portion 7 is wider (see FIG. 5).

The end portion of the hollow portion 13 on the rim portion 9 side is closed by the bottom wall of the rim portion 9. Further, a through hole 14 penetrating inside and outside the thin portion 8a is provided on a side surface of the spoke portion 8 near the rim portion 9 side. This through hole 1
4 functions as a core holding hole during a casting operation or as a compressed air supply hole for discharging the foundry sand inside, and as a drain hole during traveling. In addition, the hollow portion 13
The end portion on the side of the hub portion 7 is in communication with the lightening portion 11, and the lightening portion 11 is in communication with the outside through the opening 12.

The mold and core used to manufacture the cast wheel 5 will be described. The casting mold of the casting wheel 5 is
As shown by the chain double-dashed line in FIGS. 1 and 2, left and right molds 20 and 21 are divided into left and right halves located on both sides in the axle direction, and upper and lower mold halves 22 and 23 that surround the outer periphery are divided into upper and lower halves. It is composed of a combination of. When casting is performed by using the respective molds 20 to 23, first, the lightening portion 11 of the hub portion 7 is first formed.
And cores 24 and 25 for forming the hollow portions 13 of the spoke portions 8 are set. In this case, the cores 24 and 25 are set in a state where both are integrally assembled and fixed in advance. The cores 24, 25 may be manufactured as an integrated single body from the beginning. Further, the opening 12 of the hub portion 7 is provided with a pressing portion 26 of the core 24 by the molds 20 and 21.
Therefore, the through hole 14 of the spoke portion 8 serves as a pressing portion of the core 25 by the mold 21.

Next, the function and effect of this embodiment will be described. In a wheel of a motorcycle or the like, a large load in the rotational direction acts on the spoke portion due to acceleration or deceleration of the motorcycle or the like. Therefore, in designing the wheel, it is necessary to reduce the weight while ensuring the rigidity against bending and the like in the rotation direction. The spoke portion 8 of the present embodiment has an oval shape whose cross-section is long in the rotation direction, so that the rigidity in this rotation direction can be improved. Therefore,
When the rigidity is the same, the circumference can be shortened or the wall thickness can be reduced, and the weight can be reduced accordingly.

Further, in this embodiment, since the spoke portions 8 are formed in an oval shape and the lateral width b in the axle direction is narrowed, the projected area when viewed in the rotation direction as compared with the spoke portions having the above-mentioned H section and cross section. Can be made smaller. Therefore, air resistance during rotation can be reduced, which is advantageous in suppressing resistance during traveling. Moreover, since the lateral width b of the spoke portion 8 of the present embodiment is narrower toward the outer peripheral side where the rotation speed is faster, the air resistance can be reduced also from this point.

Furthermore, since the spokes 8 are oval in shape, mud and the like are less likely to adhere to the spokes 8 during running, and can be easily washed off by car washing. In comparison, the appearance can be kept good.

Further, in this embodiment, since the front-rear length a of the spoke portion 8 is made smaller toward the hub portion 7 side, the opening 12 formed on the outer peripheral surface of the hub portion 7 can be made larger, which is also lightweight. Can be realized. Also this opening 12
Serves as an opening for discharging core sand during casting, but since the opening 12 can be made large as described above, discharging of the sand can be facilitated. In this embodiment, since the hollow portion 13 of the spoke portion 8 and the lightening portion 11 of the hub portion 7 are communicated with each other, the cores 25 and 24 for forming the hollow portion 13 and the lightening portion 11 are connected to each other. Since it can be integrated, the strength of the entire core can be improved. Further, by utilizing the through hole 14, the tip of the integral core can be supported, and by utilizing the opening 12, the integral core can be supported.
Ru can be used to support the lightening portion of the child. Therefore, it is possible to improve the casting accuracy by preventing the core from being deformed and displaced during pouring during the casting operation. As a result, the spoke portion 8 and the hub portion 7 can be formed more uniformly and thinly, which contributes to weight reduction. Further, the through hole 14 and the axle is parallel to the surface of the side wall of the spoke portion 8 and sets the smaller diameter, and the rim portion
Since it is formed in a close portion, the rigidity of the wheel in the rotation direction is not reduced, and it is difficult to receive dynamic pressure during traveling and centrifugal force acts, so that the spoke portion 8 is provided.
The water accumulated inside can be easily discharged.

In the above embodiments, the front wheels of the motorcycle have been described, but the present invention can be applied not only to the rear wheels of the motorcycle but also to the front wheels and rear wheels of other vehicles.

[0021]

As described above, according to the cast wheel for a two-wheeled vehicle of the present invention, since the cross-sectional shape of the spoke portion is a substantially elliptical wing whose front-rear length is longer than its lateral width, necessary rigidity is secured. However, the weight can be reduced, the air resistance during rotation can be reduced, and the appearance can be prevented from deteriorating. The front-rear length is closer to the rim portion and is closer to the hub portion.
Since it is made short, the opening formed on the outer peripheral surface of the hub part
The degree of freedom of position can be expanded and the opening can be enlarged.
It is also possible to reduce the weight from this point,
It also has the effect of facilitating the discharge of core sand. In addition, the outer end opening of the hollow portion is closed by a rim portion, the hollow portion and the lightening portion of the hub portion are communicated with each other, and a through hole is formed in a side surface of the spoke portion in the vicinity of the rim portion. Since the opening is formed, it is possible to improve the strength of the core itself by integrating the core for hollow portion and the core for lightening portion, and it is possible to support both the tip portion and the hub portion of the integral core, This has the effects of preventing deformation and displacement of the core during casting and improving casting accuracy, and further ensuring rigidity in the rotational direction and facilitating drainage.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a view taken along the line III-III in FIG.

4 is a sectional view taken along line IV-IV in FIG.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a side view showing the front portion of the motorcycle equipped with the casting wheel of the above embodiment.

[Explanation of symbols]

 5 Casting wheel 7 Hub part 8 Spoke part 9 Rim part 11 Lightening part 13 Hollow part

Claims (1)

(57) [Claims] 1. A hub portion, a rim portion, and a plurality of spoke portions erected at intervals between the hub portion and the rim portion in the rotational direction, the spoke portion having a hollow portion therein. In a casting wheel for a two-transmission vehicle integrally cast to have a hollow structure in which the hub portion has a lightening portion inside, in the transverse cross-sectional shape of the spoke portion, the length in the rotational direction (longitudinal length) is the length in the axial direction. (Width) Almost oblong wing shape longer than (width) and above
The front-rear length is longer as it is closer to the rim and shorter as it is closer to the hub.
Then , while closing the outer end opening of the hollow portion with the bottom wall of the rim portion, the hollow portion and the lightening portion of the hub portion are communicated with each other,
Through holes and openings corresponding to the core holding portion for integrally holding the hollow portion forming core and the lightening portion forming core in the mold are formed in the spoke portion and the hub portion, respectively. A cast wheel for a motorcycle, wherein the through hole is formed in a portion of a side wall of the spoke portion facing the axle direction and close to the rim portion and having a small diameter for communicating the hollow portion with the outside.