JPH02106416A - Trailing arm for suspension - Google Patents

Abstract

PURPOSE:To increase freedom of shape design, avoid stress concentration, and improve reliability by integrally casting outer and inner arms extending in two branches and a housing on a main shaft side. CONSTITUTION:The main part 1 of a trailing arm is provided at its one end with an inner arm 2 and an outer arm 3 respectively extending in two branches and at is other end with a bearing housing 5 for supporting a wheel shaft 4. At the joint portion of the two arms 2, 3 and the housing 5, a coil spring mounting seat 6 is formed. At a location between the mounting seat 6 and the housing 5, a through hole 7 is formed. Here, at least both arms 2, 3 and the housing are integrally cast. Thus shape design freedom is increased, stress concentration is avoided, weight is reduced, and reliability is improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a trailing arm (hereinafter simply referred to as a "trailing arm") for a suspension system for vertically swingably connecting an axle to a frame. ), and particularly relates to a trailing arm in which an inner arm and an outer arm are bifurcated on the frame side, and a housing is formed on the main shaft side.

[Conventional technology]

Conventional trailing arms of this type include those that have a structure in which the structures of a shooting sheet metal press are welded together, as well as those that have a welded structure of a cast structure and a sheet metal press structure. was.

[Problem that the invention seeks to solve]

However, such conventional trailing arms have the following problems.

■ Welded structures of sheet metal presses Many structures of sheet metal presses are joined together by welding, and areas with high loads, such as near the housing formed on the axle side of the trailing arm, This has been countered by increasing the thickness of the plate or by overlapping two plates, but stress is concentrated in areas where the plate thickness or wall thickness suddenly changes. In addition to being forced to extend the length, there are many welded parts with low fatigue strength and reliability, making it difficult to reinforce them and requiring a long time to develop.

■ Welded structures made by casting and sheet metal presses Spheroidal graphite cast iron, which has good castability, has poor weldability, so it is possible to cast a metal with good weldability into a casting and then attach a sheet metal press structure to that metal. Welded structure (Japanese Unexamined Patent Publication No. 61-50809)
There are also known structures in which white-core malleable cast iron, which has poor castability but good weldability, is welded to sheet metal press structures, but both require special treatment. Since it is a welded structure, not only does the manufacturing cost increase significantly, but also, as in (2) above, because it is a welded structure, there is a limit to improving the reliability of the trailing arm and shortening the development period.

[Means to solve the problem]

This invention was invented to solve the above-mentioned problems, and provides a trailing arm for a suspension in which an inner arm and an outer arm are bifurcated on the frame side, and a housing is formed on the main shaft side. ,
This trailing arm for a suspension is characterized in that at least its inner arm, outer arm, and housing are integrally cast.

[Action of the invention]

The function of the trailing arm of this invention is that at least the inner arm, outer arm, and housing are integrally cast, so the degree of freedom in designing the shape can be increased, and the wall thickness can be increased where necessary for strength. At the same time, the wall thickness can be temporarily reduced in areas where the load is relatively low, making it possible to create a design that does not cause localized stress concentration, greatly improving reliability and shortening the development period. It is possible.

[Explanation of Examples]

Embodiments of the trailing arm of the present invention will be described based on FIGS. 1 to 8. First, as shown in FIG. 1, its shape is such that an inner arm 2 and an outer arm 3 are bifurcated on one side of a trailing arm body 1, and a bearing for holding an axle 4 is formed on the other side. A coil spring mounting seat 6 is formed at the base of both arms 2.3 and the housing 5, and the cross sections of the inner arm 2 and outer arm 3 are arranged in the third and fourth sections. As shown in the figure, the cross section from the coil spring mounting seat 6 to the bearing housing 5 is formed as a closed cross section in the shape of a mouth as shown in FIG. Communication holes 7 are formed at both ends of both the upper and lower surfaces of the coil spring mounting seat 6, which has a closed cross section, and the bearing housing 5, to communicate between the inside and the outside, and are used to prevent paint from remaining or to drain water. The material is spheroidal graphite cast iron with a ferrite structure as its main component.

Next, a method of manufacturing this monolithic casting trailing arm will be explained.

The chemical composition of the spheroidal graphite cast iron in this example is C: 3°63
Weight %, S i ; 2.85 weight %, M n : 0.
29% by weight, S; 0.009% by weight, Mg20.04
1% by weight and the balance iron. The range of chemical components of this spheroidal graphite cast iron is not particularly limited, but C: 3.0 to 4.0% by weight, Si: 1.80 to 4.0% by weight.
The chemical composition range of 0% by weight, Mn: 0.5% by weight or less, S: 0.02% by weight or less, Mg: o, 035 on the top of the background and the balance iron is important for castability, spheroidization of graphite, mechanical It has better effects due to its physical properties. In addition to the spheroidal graphite cast iron used in this embodiment, aluminum alloy castings, magnesium alloy castings, malleable cast irons, etc. can also be used as the material for the castings of the present invention. Next, the casting method will be explained.

As shown in FIGS. 6 to 8, since the inner arm 2 and outer arm 3 from the vicinity of the coil spring attachment part 6 to the frame side form an open cross section, a cavity 9 is formed only by the main mold 8, and the strength is required. In order to form a closed cross section from the vicinity of the coil spring attachment part 6 to the axle attachment part 5, a core 10 is placed between the main molds 8, and the core 10 is placed between the upper and lower parts of both ends. A baseboard 11 protruding from each side is inserted into the recess of the main mold 8 and held therein, and the core 10 is made of a shell core or a call box core with good collapsibility. .

Further, as shown in FIG. 7, a weir 12 is provided at the branching part of the inner arm 2 and the outer arm 3, and a weir 13 is placed on the top of the weir 12, and an outlet 14 at the bottom of the weir 13 is placed.
A stopper 15 is inserted into the weir 1, and the molten metal is poured into the weir 1.
3, and the stopper 15 is raised to inject in a short time. In addition, this bottom outlet 14 is located directly above the core lO, which is placed from the vicinity of the coil spring attachment part 6 to the axle attachment part 5, and the core is always kept at a high temperature during pouring. Since it comes into contact with the molten metal, it is possible to improve the collapsibility of the core 10, making it easier to take out the core sand, and by providing the weir 12 at this branching part, the thin-walled both sides can be removed. Arm 2.
3 can be solidified almost simultaneously, so deformation of both arms 2.3 can be prevented. Also, 7th.
As shown in FIG. 8, a hot water pool 16 is provided at the tip of the inner arm 2 or outer arm 3 (inner arm 2 in this embodiment). This means that the molten metal flowing from the weir generally passes through the long arm section to the tip section. At this time, the molten metal carries impurities such as dust between the molten metal and is forced to lower the temperature of the molten metal. However, this hot water pool 1
By having 6 at the tip, the impurities and the molten metal whose temperature has decreased can enter the molten metal pool 16, and the thin casting space 9, which will become the product part, can be made into a sound casting.

As shown in FIG. 1, the moldable trailing arm having an integral structure formed in this way has the tips of the inner arm 2 and outer arm 3 connected to the body bracket 17 so as to be able to swing in the vertical direction, respectively. A bearing (not shown) and an axle 4 are inserted into the housing 5, and a drum hub 18. The wheel 19 and tire 20 are connected in sequence.

〔Effect of the invention〕

As described above, in the trailing arm of the present invention, at least the inner arm, outer arm, and housing are integrally cast, so the degree of freedom in designing the shape can be increased, and where necessary for strength, the In addition to increasing the thickness, it is also possible to temporarily reduce the wall thickness in areas where the load is relatively low, making it possible to design a design that does not cause localized stress concentration and minimizing the increase in weight. It is something.

[Brief explanation of drawings]

Fig. 1 is a plan view of an embodiment of the present invention, Fig. 2 is a side view of the same, Fig. 3 is an enlarged sectional view taken along line mm in Fig. 1, and Fig. 4 is an enlarged view of the IV-IV cotton in Fig. 1. 5 is an enlarged sectional view taken along the line V-V in FIG. 1, FIG. 6 is a plan view of a lower mold for manufacturing the trailing arm of the present invention, and FIG. 7 is a cross-sectional view of FIG. ■ Cross-sectional view taken along the line, FIG. 8 is a cross-sectional view taken along the ■-■ line in FIG. 6.

Claims (1)

[Claims] (1) In a suspension trailing arm in which an inner arm and an outer arm are bifurcated on the frame side and a housing is formed on the main shaft side, at least the inner arm, outer arm, and housing are integrally cast and molded. A trailing arm for suspension that is characterized by: