JP2682804B2 - Wheel design method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of designing a wheel having a disk portion whose cross-section has an uneven cross section by reinforcing the inner side.

[0002]

2. Description of the Related Art When a wheel portion consisting of tires and wheels collides obliquely with an obstacle on the shoulder of a road when a passenger car is running, when the air leakage occurs due to cracking or deformation of the wheel, the wheel portion suddenly functions. Is lost, and drivability deteriorates, resulting in an extremely dangerous state. Therefore, the Ministry of Transport's "Technical Standards for Light Alloy Disc Wheels for Passenger Vehicles" and "Light Alloy Disc Wheels" of the Japan Automobile Manufacturers Association stipulate that impact strength must be confirmed for automobile wheels. Has been done.

Therefore, when designing a wheel, it is determined by the design load of the wheel with respect to the rim flange portion of the wheel fixed so that the rotation axis forms an angle of 13 ° ± 1 ° with respect to the vertical direction. Drop the weight of
The impact strength of the wheel is confirmed by conducting an impact test to confirm whether harmful cracks or the like are generated on the wheel (see FIG. 3).

Further, in the above impact test, when bending stress is generated in the wheel due to the drop load (bending load) of the weight, as shown in FIG.
There may be a crack 52 on the outer side of. Since the outer side crack 52 is a typical form of fracture in which the wheel 50 fails the impact test, conventionally, when designing the wheel 50, attention is paid to the outer side bending stress, The strength is improved by increasing the section modulus of the section of the disk portion 51 on the outer side to reduce bending stress.

Therefore, the conventional method of designing the wheel 50 will be described in detail. As shown in FIG.
Wheel 5 for rim diameter, offset, disc design, etc.
After the design condition of 0 is determined (S11), the cross-sectional shape of the disk portion 51 is determined so as to reduce the bending stress on the outer side when the bending load at the time of collision acts to an allowable value or less. (S12). Then, after the wheel 50 is prototyped on the basis of the above decision items (S13), the above-described impact test (JWL evaluation test) is performed (S14). As a result, if the breakage of the wheel 50 is confirmed, the determination of the cross-sectional shape of the disk portion 51, the trial manufacture, and the impact test in S12 to S14 are repeated (S15). On the other hand, if it is not confirmed that the wheel 50 is broken, the design is finished because the impact strength of the wheel 50 is sufficiently obtained (S).
16).

[0006]

By the way, since the outer side of the disk portion 51 is the design surface of the wheel 50, it is difficult to reinforce it by increasing the wall thickness.
Therefore, conventionally, when increasing the section modulus on the outer side, the inner side is increased in thickness or is reinforced by ribs or the like, and the disc portion 51 has a neutral axis of bending on the outer side. It has a biased cross section (see Fig. 2).

In the above-mentioned uneven cross-section, the cross-section modulus on the inner side is often smaller than that on the outer side, and the tensile bending stress generated on the inner side of the disk portion 51 at the time of bending back is increased. I am letting you. Therefore, the conventional wheel 50 has a problem that the inner side surface of the disk portion 51 is apt to be broken at the time of bending back, and in particular, this problem is that the wheel 50 is formed by a cast material having low strength. Has become noticeable. As a result, when designing the wheel 50, the determination of the cross-sectional shape of the disk portion 51, the trial manufacture, and the impact test are to be repeated many times.

Therefore, the present invention is intended to provide a wheel design method capable of reducing the repetition of the determination of the cross-sectional shape of the disk portion 51, trial manufacture and impact test.

[0009]

In order to solve the above-mentioned object, the design method according to claim 1 is such that the cross-sectional shape of the disk portion whose cross-sectional shape is made uneven by reinforcing the inner side is the outer side. The cross-section coefficient Z _O and the cross-section coefficient Z _I on the inner side are set so as to satisfy the relationship of 0.95Z _O > Z _I > 0.8Z _O , and have the following characteristics.

That is, the cross-sectional shape of the disk portion is determined so that the bending stress on the outer side at the time of collision is reduced to the allowable value or less, and the bending stress on the inner side at the time of bending back after the collision is reduced to the allowable value or less. After that, a trial production and an impact test are performed, and the quality of the determined cross-sectional shape is confirmed, whereby the cross-sectional shape is designed to satisfy the relationship of the above-mentioned cross-section coefficients.

[0011]

SUMMARY OF] According to the configuration determined by the above design method, the section modulus Z _I of the section modulus of the outer side Z _O and the inner side satisfy the relation of 0.95Z _O> Z _I> 0.8Z _O Thus, the cross-sectional shape of the disk portion is set.
0.95Z _O> to that the Z _I is to prevent the waste of material due to excessive stiffening. On the other hand, Z _I > 0.8Z _O
The reason is that the strength of the inner side of the disk portion is relatively increased as compared with the outer side, so that the occurrence of breakage from the inner side surface at the time of bending back is prevented.

Therefore, if the wheel formed by the above-mentioned designing method is designed so as to prevent breakage on the outer side, the tensile bending stress generated on the inner side of the disk portion upon bending back increases. Even so, it is possible to prevent the inner side from being destroyed together with the outer side. Accordingly, by designing the wheel so as to satisfy the above relationship, it is possible to reduce the repetition of the determination of the sectional shape of the disk portion, the trial manufacture, and the impact test.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The wheel according to the present embodiment is formed of a material obtained by casting or forging an aluminum alloy, and as shown in FIG. 1, a rim 1 joined to the inner peripheral portion of the tire.
And a plurality of disc portions 2 formed from the rim 1 toward the hub 3 on the outer side of the rim 1. As shown in FIG. 2, the cross-sectional shape of the disk portion 2 is an eccentric cross section in which the neutral axis of bending is close to the outer side, and the cross-sectional modulus of the outer side and the inner side is Z _O and Z _I , respectively. , (1) are satisfied. It should be noted that the condition of the expression (1) is such that the cast material is inferior in strength and elongation to the forged material, so that it is possible to exert extremely preferable results by applying it to the wheel 5 formed of the cast material. _{0.95Z O> Z I> 0.8Z O} ··· (1)

In the above formula (1), 0.95Z _O >
The reason why Z _I is used is to prevent waste of material due to excessive reinforcement. On the other hand, the reason why Z _I > 0.8Z _O is to prevent the occurrence of damage from the inner surface during bending back by increasing the strength of the inner side of the disc portion 2 relative to the outer side. Is.

The method of determining Z _I > 0.8 Z _O will be described in detail. The bending moment M ₁ generated in the disk portion 2 and the bending moment M ₂ at the time of bending back are measured by the formula (2). And has a maximum value in a portion close to the hub 3. _{M 2 = (0.4~0.8) M 1} ··· (2)

Further, the maximum bending stress σ _O on the outer side,
When the relationship of the equation (3) is established with the maximum bending stress σ _I on the inner side at the time of bending back, the inner side will not be broken. σ _O ＞ σ _I ... (3)

Further, the relationship of the equation (4) exists between the bending stress σ, the bending moment M and the section modulus Z. σ = M / Z (4)

Therefore, the maximum value (0.
Focusing on 8) and finding the relationship between the section modulus Z _I · Z _O on the inner side and the outer side from equations (3) and (4), it is assumed that Z in equation (1) does not cause damage on the inner side. relationship _I> 0.8Z _O will be obtained.

In the above structure, Z _I > of the formula (1)>
By setting the cross-sectional shape of the disc portion 2 so as to satisfy the relationship of 0.8Z _O, it was confirmed that can prevent the occurrence of the inner side fracture.

That is, first, 1 from the center of rotation of the wheel 5.
FIG. 4 shows the sectional shape of the disc portion 2 at the position of 00 mm.
The cross-sectional modulus Z _O on the outer side and the cross-sectional modulus Z _I on the inner side are each 7280 (m
A wheel 5 having a disc portion 2 of m ⁴ ) and 5600 (mm ⁴ ) was prepared as a comparative example. After that, the cross-sectional shape of the disk portion 2 at a position 100 mm from the rotation center of the wheel 5 is set as shown in FIG. 5, and the cross-sectional coefficient Z _O on the outer side and the cross-sectional coefficient Z _I on the inner side are 4530 (mm ⁴ ) And a wheel portion 5 having a disk portion 2 of 3860 (mm ⁴ ) were prepared as an example.

Next, after the tires were mounted on the above-mentioned wheels 5, an impact test was carried out. That is, as shown in FIG. 3, the wheel 5 on which the tire 4 is mounted is placed on the wheel mount 6, and the rotation axis of the wheel 5 is set to 1 with respect to the vertical direction.
It was fixed so as to form an angle of 3 ° ± 1 °. Then, the weight 7 having a weight determined by the design load of the wheel 5 was allowed to fall freely on the rim 1 of the wheel 5, and it was confirmed whether or not there were cracks or significant deformation harmful to the wheel 5, and sudden air leakage. Table 1 shows the test results.

[0022]

[Table 1]

The reason why the rotation axis of the wheel 5 is set at an angle of 13 ° ± 1 ° with respect to the vertical direction is that the collision angle is assumed when a collision with an obstacle existing on the road shoulder is assumed in a normal running state. This is because if θ is too small, the relative speed between the passenger car and the obstacle does not increase, while if the collision angle θ is too large, the relative speed increases, but the wheel 5 does not come into contact with the obstacle.

As a result of the above-mentioned impact test, as shown in Table 1, it was confirmed that the wheel 5 prepared as a comparative example had a crack on the inner side of the disk portion 2. On the other hand, no crack was confirmed in the wheel 5 produced as an example. The reason for this is that the wheels 5 of the embodiment, although lower than the section modulus of the section modulus of the outer side and inner side Z _O · Z _I is a comparative example Z _O · Z _I, have fallen sectional rigidity Therefore, it is considered that the load acting on the wheel 5 at the time of impact is reduced, and the bending moment at the time of impact and at the time of bending back is reduced.

As a result, in the comparative example, the section modulus Z _O on the outer side and the section modulus Z _I on the inner side are 1: 0.
In the embodiment, the outer side section modulus Z _O and the inner side section modulus Z _I are 1: 0.
Since that is a 85 relationship, if satisfied the relation of Z _I> 0.8Z _O of the cross-sectional shape of the disc portion 2 (1), the generation of the inner side destruction can be prevented with the outer side It was confirmed that

Next, a method of designing the wheel 5 having the above structure will be described. First, as shown in FIG. 6, design conditions of the wheel 5, such as a rim diameter, an offset, and a disc design, are determined (S1). After that, the cross-sectional shape of the disc portion 2 is determined so that the bending stress on the outer side when the bending load at the time of collision acts is reduced to an allowable value or less (S2). Then, the cross-sectional shape of the disc portion 2 is determined so as to reduce the bending stress on the inner side when the bending-back load is applied at the time of bending-back after the collision to be less than or equal to the allowable value (S3).

When the cross-sectional shape of the disk portion 2 is determined by paying attention to the bending stress on the outer side and the inner side by carrying out the above S2 and S3, the wheel 5 is prototyped based on these determination items. (S4).
Then, when the above-described impact test is performed (S5) and the destruction of the wheel 5 is confirmed, the determination of the cross-sectional shape of the disk portion 5 in S2 to S5, the trial manufacture, and the impact test are repeated. . On the other hand, if it is not confirmed that the wheel 5 is broken, the design should be terminated assuming that the cross-sectional shape of the disk portion 2 satisfies the condition of the formula (1) that can sufficiently obtain the impact strength of the wheel 5. Becomes (S
7).

[0028]

As described above, according to the present invention, the bending stress on the outer side at the time of collision is reduced to the allowable value or less, and the bending stress on the inner side at the time of bending back after the collision is reduced to the allowable value or less. After determining the cross-sectional shape of the disk portion as described above, a trial production and an impact test are performed, and by confirming the quality of the determined cross-sectional shape, the cross-sectional coefficient Z _O on the outer side and the cross-sectional coefficient Z _I on the inner side are determined. Is 0.95
Since the cross-sectional shape of the disc is designed so as to satisfy the relationship of Z _O > Z _I > 0.8Z _O , the strength of the inner side of the disc is relatively higher than that of the outer side and the inner side is Since it is possible to prevent the destruction of the disk together with the outer side, it is possible to reduce the repetition of the determination of the sectional shape of the disk portion, the trial manufacture, and the impact test.

[Brief description of the drawings]

FIG. 1 is a front view of a wheel.

FIG. 2 is a cross-sectional view of the disc portion of FIG. 1 taken along the line AA.

FIG. 3 is an explanatory diagram showing a state of performing an impact test.

FIG. 4 is an explanatory diagram showing a cross-sectional shape of a disc portion.

FIG. 5 is an explanatory diagram showing a cross-sectional shape of a disc portion.

FIG. 6 is a flowchart showing a wheel design method.

FIG. 7 shows a conventional example and is a cross-sectional view of a wheel.

FIG. 8 shows a conventional example and is a flowchart showing a wheel design method.

[Explanation of symbols]

 1 rim 2 disk part 3 hub 4 tire 5 wheel 6 wheel mount 7 weight

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-306101 (JP, A) JP-A-5-58105 (JP, A) Actually open 62-78501 (JP, U) Actually open 62- 65301 (JP, U) Actually opened Sho 58-70901 (JP, U) Actually opened 62-58201 (JP, U) Japanese Patent Sho 48-5123 (JP, B1)

Claims (1)

(57) [Claims] 1. The cross-sectional shape of the disk portion whose cross-sectional shape is made uneven by reinforcing the inner side has a cross-sectional coefficient Z _O on the outer side and a cross-sectional coefficient Z _I on the inner side of 0.
95Z _O > Z _I > 0.8Z _O A design method of a wheel that is set to satisfy the relationship, in which the bending stress on the outer side at the time of a collision is reduced to an allowable value or less, and bending back after the collision is performed. After determining the cross-sectional shape of the disk part to reduce the bending stress on the inner side to an allowable value or less at the time, perform trial manufacture and impact test, and confirm the quality of the determined cross-sectional shape A method of designing a wheel, characterized by designing a cross-sectional shape that satisfies the relationship of coefficients.