JPH0414247Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cast iron torque rod used in a tandem axle suspension system of a vehicle.

[Prior Art] As shown in FIG. 6, a tandem axle suspension system includes a plurality of seat plates (seat brackets) 9 that are stacked on top of each other and are mounted on a seat plate (seat bracket) 9 that is rotatably supported on a trunnion shaft 10 of a vehicle frame 3. The front and rear intermediate parts of the leaf spring 8 are
It is fixed by a pair of U bolts 12 at the front and rear. Both ends of the leaf spring 8 are slidably supported by front and rear axles 7 that support the wheels 2 via pads. An eyepiece 32 of a torque rod 30 is connected by a pin via a known elastic bushing between a knuckle 5 that engages with a bracket 6 on the upper wall of the front and rear axles 7 and a bracket 4 fixed to the vehicle frame 3. Furthermore, the eyeball portions 32 of the torque rods 30 are connected between the lower end portions of the seat plate 9 and the brackets 7a on the lower walls of the front and rear axles 7, respectively.

The torque rod 30 serves to support the torque reaction force against the rotation of the wheel 2, and also to suppress the load transfer between the axles during braking and acceleration. The beam portion 31 hits a stone thrown up from the road surface, and may directly hit a protrusion on the road surface. Therefore, the eye portion 32 requires strength to withstand torque loads, and the beam portion 31 requires strength to withstand impact loads (particularly bending loads).

As disclosed in Utility Model Application Publication No. 56-33706,
The torque rod 30 described above uses a steel tube that is easily bent under bending loads for the beam portion, and forged eye portions 32 are welded to both ends of the beam portion. However, although the torque rod 30 described above is relatively lightweight, it takes time and effort to manufacture the eyepiece 32 and weld the eyepiece 32 and the beam portion 31, making it difficult to reduce costs.

In recent years, high-strength ductile cast iron (spheroidal graphite cast iron) with excellent castability and machinability has come into widespread use as automotive casting parts. Ductile cast iron is hard and has high strength against compressive loads, but has little elongation and is therefore somewhat brittle against tensile loads.

The present applicant has proposed in Utility Model Application No. 59-44271 a torque rod made of cast iron in which ductile cast iron is partially made into a pearlite structure to increase the mechanical strength of necessary parts. However, compared to a beam section made of steel pipes, the beam section cannot be said to be able to bend appropriately against the bending load and cushion the impact sufficiently. Therefore,
The cross-sectional shape of the beam part is made so that the upper half is strong against tensile loads and the lower half is strong against compressive loads. However, if the cross section of the beam portion is configured to be vertically asymmetrical, if the torque rod is assembled upside down by mistake, the action against the bending load will be reversed, and there is a risk of damage.

[Problems to be solved by the invention] In view of the above-mentioned problems, the purpose of the invention is to provide a cast iron torque rod whose beam section has a vertically asymmetric cross section that is strong against bending loads and which prevents incorrect assembly to the car body. It is about providing.

[Means for Solving the Problems] In order to achieve the above object, the structure of the present invention is such that the thickness of the beam portion is almost uniform, and the beam section has a flat horizontal wall portion and a horizontal wall portion extending downward from the horizontal wall portion. In a cast iron torque rod, which has a protruding vertical wall part and integrally has an eye part at both ends of the beam part, there is a bolt on the lower wall of the peripheral wall of the eye part, which protrudes downward and is attached to the lower wall surface of the axle when assembled in reverse. It is integrally provided with a protruding piece that abuts against and prevents incorrect assembly.

[Function] The cast iron torque rod according to the present invention integrally has a wide flat horizontal wall part and a vertical wall part extending downward from the horizontal wall part so that the cross-sectional shape is T-shaped. In response to bending loads that push up from below, the neutral layer in the cross section of the beam section is located above the vertical center, and the elongation of the horizontal wall section that receives tensile stress is small.
Vertical walls subjected to compressive stress will shrink more.
Therefore, for cast iron, which is strong against compressive stress but weak against tensile stress, the elongation of the beam part under bending load is suppressed, so damage to the beam part can be prevented.

By integrally forming protrusions that protrude downward from the surrounding wall on the eyelets at both ends of the beam, if the torque rod is in the opposite direction, the protrusions will hit the bottom wall of the axle, preventing incorrect assembly. do.

[Embodiment of the invention] Fig. 1 is a side view of a cast iron torque rod according to the invention. The present invention is to cast a torque rod using a material equivalent to cast iron, such as XFCD50 (ductile cast iron). The cross-sectional shape of the torque rod 30 includes a horizontal wall portion 21 that is wide and horizontal, and a vertical wall portion 22 that extends downward from the horizontal wall portion 21.

As shown in FIG. 2, the beam section 31 has a T-shaped cross section with a substantially uniform wall thickness, and as shown in FIG. be done.

When casting the torque rod 30 according to the present invention, the structure of the beam portion 31 may be a ferrite structure that is relatively soft and has impact resistance, and the structure of the eye portion 32 may be a pearlite structure that has high hardness and mechanical strength. preferable.

As described above, in the present invention, since the cross-sectional shape of the beam portion 31 is T-shaped, the neutral layer n against the bending load is deviated upward from the vertical center. Therefore, with respect to the bending load, the deflection (elongation δ _A ) of the horizontal wall portion 21 against the tensile stress is small, and the vertical wall portion 22
The deflection (shrinkage δ _B ) against the compressive load is large.
The T-shaped cross section of the beam portion 31 is compatible with the characteristics of cast iron, which is strong against compressive loads but weak against tensile loads, and can avoid damage to the horizontal wall portions 21 due to tensile stress.

According to the present invention, when assembling the torque rod 30, in order to prevent the horizontal wall portion 21 from being assembled with the horizontal wall portion 21 facing downward (upside down), as shown in FIG. , vertical wall part 2
A projecting piece 3 that is partially continuous with 2 and projects downward.
5 is provided. Therefore, even if the torque rod 30 is assembled upside down as shown in FIG. It cannot be inserted into the bracket 7a.

In the embodiment shown in FIGS. 4 and 5, the torque rod 30
The beam portion 31 has an inverted L-shape or an inverted U-shape in cross section. The flatness of the beam part 31 is integrally connected to the horizontal wall part 21 and the vertical wall part 22 extending downward. Since the neutral layer n of the cross-sectional shape of the beam section 31 is closer to the horizontal wall section 21 than the vertical center, the elongation due to the tensile stress of the horizontal wall section 21 is minimized in response to a bending load that pushes up the beam section 31 from below. can be suppressed.

[Effects of the invention] As described above, the present invention has a beam part with a substantially uniform wall thickness, a flat cross-section, and an integrated horizontal wall part and a vertical wall part protruding downward from the horizontal wall part. However, in a cast iron torque rod that integrally has eye parts at both ends of the beam part, a protrusion is provided on the lower wall of the peripheral wall of the eye part that protrudes downward and comes into contact with the lower wall surface of the axle during reverse assembly to prevent incorrect assembly. The cross-sectional shape of the beam part of the torque rod is made up of a flat horizontal wall part and a vertical wall part extending downward from the horizontal wall part, so that the neutral layer against bending load is at the vertical center. deviates upwards. Therefore, it is possible to minimize elongation due to tensile stress, which is a strength problem for cast iron, and to provide a cast iron torque rod that fully performs the function of a suspension system.

The torque rod according to the present invention is easy to manufacture, and by making the cross section of the beam part vertically asymmetrical, the tensile strength of the upper half is strengthened, and by providing a downward protruding piece on the eye, the torque rod can be easily manufactured. can be prevented from being assembled upside down on the axle.

[Brief explanation of the drawing]

Fig. 1 is a side view of a cast iron torque rod according to the first embodiment of the present invention, Fig. 2 is a front sectional view of the central portion of the torque rod, and Fig. 3 is a side view illustrating the assembly of the torque rod to an axle. Figures 4 and 5 are front sectional views of the central portion of torque rods according to the second and third embodiments of the present invention, and Figure 6 is a side view showing an outline of a general suspension system in which the torque rods are used. It is. 21...Horizontal wall part, 22...Vertical wall part, 30...
...torque rod, 31...beam section, 32...eyeball section, 35...protrusion piece.

Claims (1)

[Scope of utility model registration request] The thickness of the beam part is almost uniform, the cross section of the beam part integrally includes a flat horizontal wall part and a vertical wall part protruding downward from the horizontal wall part, and eye parts are integrally provided at both ends of the beam part. In cast iron torque rods,
A cast iron torque rod characterized in that a protruding piece is integrally provided on the lower wall of the peripheral wall of the centerpiece and projects downward and comes into contact with the lower wall of the axle during reverse assembly to prevent incorrect assembly.