JP3866377B2 - Body frame of motorcycle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present application relates to a body frame of a motorcycle, and more particularly, to a body frame including a pair of left and right main frames and a cross member that connects them to each other easily.
[0002]
[Prior art]
Japanese Utility Model Laid-Open No. 5-84592 discloses a pair of main frames extending rearward from the head pipe in a pair of left and right directions, a pair of left and right pivot frames extending from the rear end portions thereof, a cross member connecting the left and right main frames, A motorcycle body frame that includes various stays and is assembled by welding at respective connection ends is shown.
[0003]
Japanese Patent Application Laid-Open No. 1-212679 discloses a vehicle body frame in which a head pipe is cast integrally with a frame pipe by casting a front end portion of the frame pipe.
[0004]
[Problems to be solved by the invention]
When assembling the body frame by welding among the above conventional examples, it is necessary to set and temporarily attach the component parts with a welding jig or the like in advance, and the finishing work after welding takes a lot of labor, which increases the cost. .
[0005]
Moreover, in the case of a structure that must be welded on the back side, it becomes difficult to automate with a robot, and handwork welding is unavoidable. At this time, it is necessary to improve some external parts. Advanced skills are required. In addition, it is necessary to work and design in consideration of a decrease in material strength due to the thermal effect of welding and a decrease in dimensional accuracy due to thermal strain.
[0006]
Further, if the front end of the frame pipe is cast with a head pipe as in JP-A-1-212679, at least the welding work between the head pipe and the front end of the frame pipe can be omitted, but the vehicle body frame ensures the vehicle body rigidity. In order to do so, a cross member that connects the middle part of the left and right main frames is indispensable. Since this cross member is formed separately from the frame pipe and joined by welding, the problems associated with welding cannot be solved. .
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a first invention in the present application is a vehicle body frame of a motorcycle having a pair of left and right main frames and a cross member that connects between the middle portions of the left and right main frames. Further, the present invention is characterized in that a cast product is formed by integrally casting the outer periphery of the intermediate portion of the pair of left and right main frames at both ends in the length direction.
[0008]
Further, a through hole is formed in the insert casting of the main frame and the cross member, also characterized in that the caulking member is fixedly attached to the through hole.
[0009]
Furthermore, the second invention is characterized in that, in the first invention, the main frame has a taper with respect to a die-cutting direction of the cast-in mold.
[0010]
【The invention's effect】
According to the first aspect of the invention, the cross member is cast and the outer periphery of the intermediate portion of the main frame is cast at both ends thereof, so that the left and right main frames and the cross member can be integrated and firmly coupled to each other.
[0011]
This eliminates the need for welding after attaching a separate main frame and cross member to the jig, reducing man-hours, shortening work hours, reducing costs, and requiring a high level of skill. In addition, since it is not necessary to consider the thermal effect on the strength, the design becomes easy.
[0012]
Furthermore, in the cast-in part, through holes are made in the main frame and the cross member, and a caulking member is attached and fixed to the main frame and the cast-in part to provide a coupling strengthening part. The bond with the cross member can be strengthened.
[0013]
According to the second invention, since the side surface of the main frame is a tapered surface, the main frame and the mold are brought into close contact with each other by matching the inner surface of the mold with the tapered surface during casting. As a result, the appearance after casting is improved, and finishing work such as deburring is reduced, so that workability is improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
1 is a developed perspective view of a body frame of a motorcycle according to the present invention, FIG. 2 is a side view of a cast-in part, FIG. 3 is a plan view of a left side portion of the body, and FIG. 4 is a cross-sectional view taken along line -4, FIG. 5 is a cross-sectional view showing a mold structure at the time of casting, and FIG.
[0015]
First, the overall structure of the body frame of this motorcycle will be outlined with reference to FIG. The vehicle body frame includes a front portion 1 having a substantially V shape in a plan view, a main portion 2 having a substantially H shape in a plan view, and a pair of left and right pivot frames 3 attached to a rear end portion of the main portion 2.
[0016]
The front portion 1 is integrally formed with a head pipe 4 at the tip portion, and includes a square pipe-shaped arm portion 5 that extends rearward while expanding left and right, and is cast from a light alloy material such as an aluminum alloy.
[0017]
In addition, the front part 1 may be formed by welding the head pipe 4 and the arm part 5 separately from each other without depending on the cast product.
[0018]
The main portion 2 is integrated by a pair of left and right main frames 6 extending in a substantially straight line in the front-rear direction, and a cross member 7 that connects between these intermediate portions, and the connecting portion between the main frame 6 and the cross member 7 is a cross. It is a cast-in part 8 that is continuous with the member 7.
[0019]
The upper portion of the cast-in portion 8 is formed with a strengthening portion 9 for coupling with the main frame 6, stays 10 and 11 extending vertically to support a fuel tank (not shown), and a substantially horizontal inside of the vehicle body. A stay 12 is integrally formed, and a stay 13 for an engine hanger is integrally formed at the lower part of the cross member 7 so as to protrude downward.
[0020]
The main frame 6 is formed by extrusion using a light alloy material such as an aluminum alloy, and a rib wall 14 is integrally formed continuously in the length direction so that the cross section has a substantially square shape inside. .
[0021]
The side surface of the main frame 6 has tapered surfaces 16 and 17 that taper upward and downward from the middle in the vertical direction, with the ridgeline 15 being the same, and this structure is the same on both the left and right sides.
[0022]
The front end portions of the left and right main frames 6 are fitted to the end portions of the left and right arm portions 5 and welded at the fitting portions, whereby the front portion 1 and the main portion 2 are coupled.
[0023]
The pivot frame 3 is a cast product that is formed long in the vertical direction by using a light alloy material such as an aluminum alloy, has a bilaterally symmetric shape, and has a coupling protrusion 18 that protrudes forward on the front edge side. The main part 2 and the pivot frame 3 are integrated by fitting with the rear end parts of the left and right main frames 6 and welding at the fitting parts.
[0024]
A boss portion 19 is formed on the lower side surface of the pivot frame 3, and a front end portion of a rear arm constituting a rear wheel suspension device (not shown) is pivotally coupled to be swingable.
[0025]
Next, the structure of the cross member 7 and the cast-in part 8 will be described with reference to FIGS. As shown in these drawings, the cross member 7 is cast into a shape hollowed out by a concave portion that opens downward using a light alloy material such as an aluminum alloy, and a plurality of lateral ribs 20 extending in the left-right direction extending in the left-right direction. And it is reinforced by the vertical rib 21.
[0026]
The stay 13 extends downward continuously from the top 22 of the cross member 7 and forms a part of a vertical rib. Ribs 23 parallel to the lateral ribs 20 are also formed between the left and right sides of the stay 13 and the bottom of the cross member 7.
[0027]
When the cross member 7 is a cast product, the cast hole portion 8 is formed by continuously casting the outer periphery of each intermediate portion of the left and right main frames 6 so as to be integrated integrally with both end portions of the cross member 7 in the left and right direction. The stays 10, 11, and 12 are also integrally formed.
[0028]
FIG. 5 shows a state in which the front part or the rear part of the main frame 6 is set between the upper mold 30 and the lower mold 31 in the cast product with respect to the cast-in part 8 and the upper mold 30 and the lower mold 31 are aligned. The surface 32 coincides with the ridgeline 15 of the main frame 6, and the inner surfaces of the cavities 33 and 34 are tapered surfaces corresponding to the tapered surfaces 16 and 17 of the main frame 6.
[0029]
The left and right main frames 6 have a width in the left-right direction that is maximum at the ridge line portion 15, and the tapered surfaces 16 and 17 that are side surfaces have an angle θ so that both the upper end portion and the lower end portion are narrower than this. As a result, it forms a tapered shape that gradually becomes narrower from the ridge line portion 15 toward the die cutting direction Z.
[0030]
Accordingly, when the main frame 6 is set in the cavities 33 and 34, the inner surfaces of the cavities 33 and 34 correspond to the tapered surfaces 16 and 17, respectively, so that the tapered surfaces 16 and 17 are tapered. Each of the cavities 33 and 34 can be hermetically in close contact with the mold surfaces.
[0031]
In addition, although it is not clear in FIG. 5, naturally the caditi corresponding to these is formed in the part which forms the cross member 7 and the cast-in part 8 of the upper mold | type 30 and the lower mold | type 31.
[0032]
Therefore, if the left and right main frames 6 are set between the upper mold 30 and the lower mold 31 and a molten light alloy material such as an aluminum alloy is injected, the intermediate portions of the cross member 7 and the left and right main frames 6 are cast. The main cast part 8 in which the cast-in part 8 and the stays 10, 11, 12, 13 are integrally formed is obtained.
[0033]
After the casting, as shown in FIG. 6, the connection between the main frame 6 and the cast-in part 8 is reinforced. That is, a through hole 25 is first drilled (B) with respect to A in the figure immediately after casting (B), and then a commercially available caulking nut 26 is attached to this hole (C), and the caulking nut 26 is caulked. As a result, the cast-in part 8 and the main frame 6 are firmly coupled, and relative displacement in the axial direction of the cast-in part 8 and the main frame 6 is prevented.
[0034]
In addition, if necessary, another joint strengthening part used in place of or in combination with the top joint strengthening part 9 can be provided and strengthened at an arbitrary place such as a side surface as shown by a virtual line in FIG. .
[0035]
In addition, when not so high bond strength is required, it can be replaced with a commercially available cashmere bed.
[0036]
Next, the function and effect of this embodiment will be described. First, the cross member 7 is formed by casting, and the outer periphery of the intermediate portion of the main frame 6 is cast at both ends thereof, so that the left and right main frames 6 and the cross member 7 can be integrated and firmly coupled to each other.
[0037]
For this reason, since it is not necessary to weld the main frame 6 and the cross member 7 separately attached to the jig, the man-hours are reduced, the working time is shortened, the cost is reduced, and the skill level is increased. It is not required, and it is not necessary to consider the thermal effect on the strength so that the design is facilitated.
[0038]
Furthermore, since the side surfaces of the main frame 6 are tapered surfaces 16 and 17, the inner surfaces of the cavities 33 and 34 provided in the mold are made to correspond to the tapered surfaces, so that the tapered surfaces 16 and 17 of the main frame 6 are formed. Since the molds are in close contact with the inner surfaces of the cavities 33 and 34 by taper matching, it is difficult for casting burrs to occur during casting. As a result, appearance after casting is improved and finishing work such as deburring is reduced. Therefore, workability is improved.
[0039]
In addition, in the cast-in part 8, a through-hole 25 is formed in the main frame 6 and the cross member 7, and a coupling strengthening part 9 is formed by caulking the main frame 6 and the cast-in part 8 with a caulking nut 26 that is a caulking member. Thus, the coupling with the cross member 7 in the axial direction of the main frame 6 can be strengthened.
[0040]
In addition, since the various stays 10, 11, 12, and 13 can be formed integrally when the cross member 7 and the cast-in part 8 are cast, the labor of welding after forming these separately is also eliminated.
[0041]
In addition, the cross member 7 has a light and rigid structure by integrally forming the hollow recess, the horizontal rib 20 and the vertical rib 21 in a portion that is difficult to be seen, and the rib 23 is formed between the stay 13 and the cross member 7. The stay 13 is sufficiently strengthened by being formed integrally therewith.
[0042]
The present invention is not limited to the above-described embodiments, and can be variously modified. For example, the main frame 6 can be a pipe member such as iron, each stay can be a separate press product, and a pipette frame can be used. 3 can also be a press product.
[0043]
Further, if the cross member 7 and the cast-in part 8 are formed in the connection part of the front part 1 and the main part 2 or the connection part of the main part 2 and the pivot frame 3 or all of them, the front part 1, the main part 2 and the pivot frame The welding between 3 can be omitted.
[Brief description of the drawings]
FIG. 1 is a developed perspective view of a body frame of a motorcycle according to the present invention. FIG. 2 is a side view of a cast-in part. FIG. 3 is a plan view of a left side portion of the body. Cross-sectional view along line 4 [Fig. 5] Cross-sectional view showing the mold structure during casting [Fig. 6] Diagram showing the step of strengthening the cast-in part [Explanation of symbols]
6: main frame, 7: cross member, 8: cast-in part, 9: joint strengthening part, 10, 11, 12, 13: stay

Claims (2)

In a body frame of a motorcycle having a pair of left and right main frames and a cross member connecting between the middle portions of the left and right main frames,
The cross member, Ri castings der I insert casting integrally intermediate portion outer periphery of the pair of left and right main frames both longitudinal ends,
A body frame of a motorcycle , wherein a through hole is formed in a cast hole portion of the main frame and the cross member, and a caulking member is attached and fixed to the through hole .   2. The body frame of a motorcycle according to claim 1, wherein the main frame has a taper with respect to a die-cutting direction of a casting mold.

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