JP2003063224A - Suspension arm for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension arm for an automobile considerably reducible in weight, while ensuring strength and rigidity, and reducing generation of cast defects and rough metallic structure by integrally casting a connecting part with a knuckle, a supporting part from a vehicle body and an arm for linking the supporting part by joint parts. SOLUTION: At least one of the connecting part and the supporting part has an axial hole within a boss. At least one of the joint parts is provided with reinforcing ribs. Crossing ribs stretching over the reinforcing ribs are formed by being slightly separated from the outside of the boss.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension arm for an automobile, which is made of a cast material and constitutes a suspension device for an automobile.

[0002]

2. Description of the Related Art A suspension of an automobile reduces vibrations and impacts transmitted from the road surface to the vehicle body to ensure a comfortable ride for an occupant and suppresses the orientation of wheels for stability in running. . Among suspensions of automobiles, for example, an independent suspension type suspension has a merit that riding comfort and running stability can be improved and unsprung load can be reduced because each wheel is individually supported by the vehicle body.

FIG. 6 shows an independent suspension type suspension 60.
An example is shown, (a) is a plan view and (b) is a front view. Incidentally, since the left and right suspensions are generally shaped differently, one suspension will be described below. The suspension 60 has a coil spring 13
And a shock absorber 14 are connected to each other, a spindle 17 for rotatably supporting a tire 16, a knuckle 18 made by casting or forging, and a ball joint having one end fixed to a lower end portion of the knuckle 18. A lower arm 11 which is connected to a vehicle body (not shown) by support portions 11b and 11c into which a rubber bush at the other end is press-fitted, and an upper end portion of a knuckle 18 which are connected to each other (not shown) by a shaft hole 11a. The upper arm 12 is connected to a ball joint (not shown) fixed to the shaft via an axial hole 12a, and the other end is supported on the vehicle body by supporting portions 12b and 12c into which rubber bushes are press-fitted. Such a suspension 60 can freely design the posture control of the vehicle body by controlling the length, shape, and arrangement of the suspension arms such as the lower arm 11 and the upper arm 12, and has high rigidity and excellent riding comfort and running stability. Therefore, it has been used in many automobiles in recent years.

Among the above-mentioned suspensions, the suspension arms such as the lower arm 11 and the upper arm 12 have complicated shapes, and are therefore manufactured by press or casting capable of complex molding. However, since a suspension arm formed by press molding is formed by pressing a thin plate and then welding, it is difficult to form the suspension arm with high strength in a narrow mounting space. Therefore, a suspension arm integrated with casting has been used.

The stress applied to the lower arm 11 and the upper arm 12 is due to the vertical load of the vehicle body during traveling, at the roots of the shaft holes 11a and 12a, which are the connecting portions with the knuckle 18, and the supporting portions 11b and 12b at the rear, When braking, at the base of the support parts 11c, 12c on the front,
Further, when cornering, they concentrate on the bases of the shaft holes 11a and 12a, which are the connecting portions with the knuckle, and the supporting portions 11b and 12b, which are on the rear side. It is said that the largest load is the vertical load of the vehicle body, and the strength is ensured so that the roots of the shaft holes 11a and 12a and the support portions 11b and 12b are not damaged even if an excessive impact load is applied. There is a need. In addition, it is necessary to secure high rigidity in order to obtain steering stability of the automobile. In order to secure this strength and rigidity, the cross section of the arm part of the lower arm and the upper arm is approximately H.
Forming and almost I-shape are performed.

FIG. 4 is a plan view of a lower arm 40 integrally formed by conventional casting. The lower arm 40 includes a connecting portion 1 for connecting a knuckle, and each shaft hole 2 serving as a supporting portion from the vehicle body.
a, 2b and an arm 4a that connects them with the connecting portions 3a to 3c
~ 4c are integrated with casting. In addition, each shaft hole 2a,
2b are formed on the bosses 9a and 9b, respectively. Then, in the arm direction of the arm portions 4a-4c, the reinforcing ribs 6a-
6e is provided and the cross section is substantially H-shaped.

FIG. 5 is a plan view of a conventional upper arm 50 which is integrally formed by casting. Similar to the lower arm 40 described above, the upper arm 50 also has a connecting portion 1 with the knuckle and shaft holes 2a, 2
b and arms 4a to 4c that connect them with the connecting portions 3a to 3d
And are cast together. The shaft holes 2a and 2b are formed in bosses 9a and 9b, respectively. Further, reinforcing ribs 6a to 6e are provided in the arm directions of the arms 4a to 4c to have a substantially H-shaped cross section. In the lower arm 40 shown in FIG. 4 and the upper arm 50 shown in FIG. 5, parts having substantially the same function are denoted by the same reference numerals.

[0008]

In order to reduce the unsprung load and further improve the fuel consumption, it is required to make the suspension arm even lighter in weight. Therefore,
It is conceivable that the arms 4a to 4c and the reinforcing ribs 6a to 6e in the lower arm 40 of FIG. 4 and the upper arm 50 of FIG. On the other hand, torsion mainly acts on the connecting portion 1 with the knuckle and the shaft holes 2a and 2b supported from the vehicle body, so that the connecting portions 3a to 4c of the arms 4a to 4c.
It is necessary to thicken 3d and its vicinity to increase strength and rigidity. However, if the connecting portions 3a to 3d and the vicinity thereof are made thick, the thickness variation of the arms 4a to 4c, the reinforcing ribs 6a to 6e, and the bosses 9a and 9b that are going to be made thin becomes large, and after casting, D1 to D in FIGS. 4 and 5
Casting defects, such as shrinkage cavities, may occur in three parts. Further, if the connecting portions 3a to 3d and the vicinity thereof are made thick, the solidification time becomes long during casting, so that the metal structure may become coarse and the strength may decrease.

Therefore, an object of the present invention is to integrally cast a knuckle connecting part, a support part from the vehicle body, and an arm connecting the knuckle with a connecting part, thereby significantly reducing the weight while ensuring strength and rigidity. It is possible to obtain a suspension arm for an automobile, which is capable of producing a casting defect and a coarse metal structure.

[0010]

DISCLOSURE OF THE INVENTION The present invention is a suspension arm for an automobile, in which a connecting portion with a knuckle, a supporting portion from a vehicle body, and an arm connecting the connecting portion with each other are integrally formed by casting. At least one of the connecting portion and the supporting portion has an axial hole in the boss, and at least one of the connecting portions is provided with a reinforcing rib, and a transverse rib straddling the reinforcing rib is slightly separated from the outside of the boss. It is characterized in that it is formed.

By providing a reinforcing rib on at least one surface of the arm in the arm direction in the vicinity of the support portion, and further by forming a transverse rib extending between the reinforcement ribs slightly apart from the outer diameter of the support portion, the transverse rib is formed. Is in the twisting direction that acts on the support portion, so that the strength and rigidity of the support portion can be secured and the weight can be reduced even if the thickness of the reinforcing rib is thin. Further, the thickness of the support portion can be reduced to reduce the variation in thickness with the reinforcing ribs, and the occurrence of shrinkage cavities after casting can be reduced. Further, the reduced wall thickness shortens the solidification time during casting and prevents the formation of a coarse metallographic structure that causes a decrease in strength.

The term "integrated casting" means that each part of the suspension arm is made of a single material and there is no joint between the parts. In addition, the arm portion includes the above-mentioned connecting portion with the knuckle, the portion connecting the support portion from the vehicle body, and the portion connecting the shock absorber attaching portion when the shock absorber attaching portion is provided. The thickness and height of the transverse ribs can be changed, and the number of transverse ribs is not limited to one, and two or more ribs may be formed at intervals.

Further, the suspension arm of the present invention is
The distance (L) to the center of the transverse rib is L = (0.5 to 2) tb with respect to the average thickness (tb) of the boss. If the separation dimension (L) from the outside of the boss to the center of the transverse rib is less than 0.5 tb, the boss becomes thick when combined with the boss, resulting in casting defects such as shrinkage cavities after casting, and a coarse metal. Tissue may occur. On the other hand, the distance (L) to the center of the transverse rib is 2
When it exceeds tb, the effect of improving the strength and rigidity of the connecting portion with the knuckle or the supporting portion from the vehicle body decreases.

Further, the suspension arm of the present invention is
The thickness (tc) of the transverse rib is tc = (0.5 to 2) tb with respect to the average thickness (tb) of the boss. When the thickness (tc) of the transverse rib is less than 0.5 with respect to the average thickness (tb) of the boss, the effect of improving the strength and rigidity of the supporting portion is small. On the other hand, the thickness of the transverse rib (tc)
Is more than 2 with respect to the average wall thickness (tb) of the boss, the thickness variation becomes large, and casting defects such as shrinkage cavities are likely to occur after casting.

Further, the suspension arm of the present invention is
It is characterized by comprising at least one of an aluminum alloy casting and a spheroidal graphite cast iron casting. As a result, the suspension arm has high toughness even in a complicated shape.

Further, according to the present invention, the connecting portion with the knuckle, the supporting portion from the vehicle body, and the arm connecting the connecting portions with each other are integrally formed of at least one of aluminum alloy casting and spheroidal graphite cast iron casting. A suspension arm for an automobile, wherein at least one of the connecting portion and the supporting portion has a shaft hole in a boss, a reinforcing rib is provided on at least one of the connecting portions, and at least the connecting portion and the supporting portion are provided. It is characterized in that the cross section of one and the connecting portion is in a shape in which a substantially + shape or a substantially + shape is directly connected to a substantially o shape. In addition,
The substantially + shape means, for example, a shape having cross ribs on the upper and lower surfaces of the arm, and the substantially “T” shape means, for example, a shape having cross ribs on either one of the upper and lower surfaces of the arm.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. In the description of the embodiment, portions having substantially the same functions as those of the conventional lower arm 40 of FIG. 4 and the conventional upper arm 50 of FIG. 5 described above are denoted by the same reference numerals.

(First Embodiment) FIG. 1 is a plan view of a lower arm 10 according to the first embodiment. Further, FIG. 3 is a perspective view of the vicinity of the support portion of the lower arm 10 from the vehicle body in the first embodiment. Lower arm 10 is (JIS) A
It is made of an aluminum alloy casting corresponding to C4CH, has a connecting portion 1 for connecting with a knuckle, a supporting portion having shaft holes 2a, 2b in each boss 5a, 5b, and connecting portions 3a to 3c.
The arms 4a to 4c which are connected with each other are integrally formed by casting. Further, thin connecting ribs 6a to 6f are provided on the connecting portions 3a to 3c to make the cross section substantially H-shaped (shown by the cross section AA). Further, the reinforcing rib 6a, the reinforcing rib 6b, and the reinforcing rib 6c.
And reinforcing ribs 6d, and thin ribs 7a to 7c that straddle the reinforcing ribs 6e and 6f, respectively, are formed slightly apart from the outside of the stealed bosses 5a to 5c (shown by diagonal lines). . From the shaft hole to the arm, the cross section of the support portion composed of the boss 5b and the shaft hole 2b in the boss 5b and the connecting portion 3b connected to the boss 5b is , And the shape of + is directly connected to the shape of ○.

Reinforcing ribs 6a-6f and transverse ribs 7a-
7c, the strength and rigidity of the lower arm 10 are improved. Further, since the reinforcing ribs 6a to 6f are thin and the bosses 5a to 5c are also stealed to be thin, the weight of the lower arm 10 is reduced. Furthermore, the transverse rib 7
Since a to 7c are formed slightly apart from the outside of the bosses 5a to 5c, respectively, the arms 4a to 4c and the boss 5 are formed.
The thickness variation with the a to 5c and the reinforcing ribs 6a to 6f is small, and the occurrence of casting defects such as shrinkage cavities after casting and the occurrence of a coarse metal structure that causes a decrease in strength are reduced.

(Second Embodiment) FIG. 2 is a plan view of an upper arm 20 according to a second embodiment. The upper arm 20 is made of a spheroidal graphite cast iron casting equivalent to (JIS) FCD450, and has a knuckle connection portion 1 and each boss 5a, 5
a support portion from the vehicle body having shaft holes 2a and 2b in b, and arms 4a and 4b connecting the support portions with connecting portions 3a to 3d.
And are cast together. Further, the connecting portions 3a to 3d are provided with thin reinforcing ribs 6a to 6h so that their cross sections are substantially H-shaped. Further, the reinforcing ribs 6a and 6b, the reinforcing ribs 6c and 6d, the reinforcing ribs 6e and 6f,
Thin cross ribs 7a to 7d extending over the reinforcing rib 6g and the reinforcing rib 6h, respectively, are slightly separated from the outsides of the bosses 5a to 5c (shown by diagonal lines) stolen only on the front surface in FIG. Has been formed. The cross section of the support portion formed of the shaft holes 2a and 2b in each of the bosses 5a and 5b and the connecting portions 3a and 3b that are connected to the support portion are formed by directly connecting a substantially letter "C" to a character "O". There is.

Reinforcing ribs 6a to 6h and thin transverse ribs 7a
At ~ 7d, the strength and rigidity of the upper arm 20 are improved. Also, the reinforcing ribs 6a to 6h are made thin,
Since the bosses 5a to 5c are also stolen and are made thin, the weight of the upper arm 20 is reduced. Further, since the transverse ribs 7a to 7d are formed slightly apart from the outer sides of the bosses 5a to 5c, the arms 4a, 4b,
Variations in wall thickness with the bosses 5a to 5c and the reinforcing ribs 6a to 6h are small, and the occurrence of casting defects such as shrinkage cavities after casting and the occurrence of a coarse metal structure causing a decrease in strength are reduced.

[0022]

EXAMPLE First, element data for analysis was prepared for the lower arm 10 of FIG. That is, in FIG. 1, the horizontal direction is about 600 mm, the vertical direction is about 500 mm, and the height is about 80 m.
m, the outer diameter of each of the bosses 5a to 5c is about 70 mm, and the shaft hole 2
The inner diameter of a and 2b is about 50 mm, the average thickness of the boss (tb)
Is about 10 mm, the thickness of the arms 4a and 4b is about 7 mm,
The reinforcing ribs 6a to 6f have a wall thickness of about 7 mm near the connecting portions 3a to 3c, and the transverse ribs 7a to 7c have a wall thickness (tc) of (0.
5-2) × tb was 7 mm and the height was 8 mm. Table 1 shows the distance (L) from the outside of the bosses 5a to 5c to the center of the transverse ribs 7a to 7c.

[0023] (Table 1)   Crossing rib Separation dimension L (mm) Ratio with average wall thickness tb of boss     7a 5.5 0.55     7b 10 1.0     7c 18 1.8

Next, using the element data for analysis, a predetermined load was applied to the connecting portion with the knuckle and the supporting portion from the vehicle body, and stress analysis was performed by a computer. as a result,
It was confirmed that the lower arm 10 had sufficient strength. Further, as a result of calculating the mass by the computer based on the data for analysis, the lower arm 10 is about 7% lighter than the conventional lower arm 40.

Next, using the element data for analysis, (JI
S) A molten metal flow solidification simulation was performed in which a molten metal to be an AC4CH aluminum alloy casting was injected. As a result, no shrinkage cavities were found in the joints.

As described above in detail, in the vehicle suspension arm of the present invention, the connecting portion with the knuckle, the supporting portion from the vehicle body, and the arm connecting the connecting portions with each other are integrally formed by casting. In addition, it is possible to significantly reduce the weight while ensuring strength and rigidity, and to reduce casting defects and coarse metal structure.

[Brief description of drawings]

FIG. 1 is a plan view of a lower arm according to a first embodiment.

FIG. 2 is a plan view of an upper arm according to the second embodiment.

FIG. 3 is a perspective view of the vicinity of a support portion of the lower arm from the vehicle body according to the first embodiment.

FIG. 4 is a plan view of a lower arm integrated with a conventional casting.

FIG. 5 is a plan view of a conventional casting integrated upper arm.

FIG. 6 shows an example of an independent suspension type suspension,
(A) is a plan view and (b) is a front view.

[Explanation of symbols]

10, 11, 40: Lower arm 12, 20, 50: Upper arm 1: Connection part 2a, 2b, 11a, 12a: shaft hole 3a to 3d: connecting part 4a-4c: arm 5a-5c: Boss 6a to 6h: Reinforcing rib 7a to 7d: Transverse rib 9a, 9b: boss 11b, 11c, 12b, 12c: support part 13: Coil spring 14: Shock absorber 15: Strut 16: Tire 17: Spindle 18: Knuckle L: Distance to the center of the transverse rib tb: Average thickness of boss tc: Thickness of transverse rib

Claims (5)

[Claims] 1. A suspension arm for an automobile, wherein a connecting portion with a knuckle, a supporting portion from a vehicle body, and an arm connecting the connecting portion with a connecting portion are cast-integrated, and at least the connecting portion and the supporting portion. One has a shaft hole in the boss, and at least one of the connecting portions is provided with a reinforcing rib,
A suspension arm for an automobile, characterized in that a transverse rib straddling the reinforcing rib is formed slightly apart from the outside of the boss. 2. The distance (L) to the center of the transverse rib is L = with respect to the average thickness (tb) of the boss.
The vehicle suspension arm according to claim 1, wherein the suspension arm has a length of (0.5 to 2) tb. 3. The wall thickness (tc) of the transverse rib is tc = (0.5 to 2) t with respect to the average wall thickness (tb) of the boss.
3. The vehicle suspension arm according to claim 1, wherein the suspension arm is b. 4. The vehicle suspension arm according to claim 1, wherein the suspension arm is made of at least one of an aluminum alloy casting and a spheroidal graphite cast iron casting. 5. A suspension for an automobile in which a connecting portion with a knuckle, a supporting portion from a vehicle body, and an arm connecting the connecting portions with each other are at least one of an aluminum alloy casting and a spheroidal graphite cast iron casting. An arm, wherein at least one of the connecting portion and the supporting portion has an axial hole in a boss, a reinforcing rib is provided in at least one of the connecting portions, and at least one of the connecting portion and the supporting portion is connected to the arm. A suspension arm for an automobile, characterized in that a cross section of the portion is formed by directly connecting a substantially O shape, a substantially + shape or a substantially C shape.