JPS5834691B2 - Leaf spring for vehicle suspension - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to a plate for suspension of a vehicle.

In leaf springs for vehicle suspension, in order to equalize stress distribution and reduce weight, the thickness decreases in the direction of the leaf ends between the central part and the leaf ends, which are connected to the vehicle wheels and body, respectively. A type having a tapered portion is known.

In a stacked leaf spring device formed by stacking a plurality of such leaf springs in the thickness direction, weight reduction can be further promoted by setting a high design stress and reducing the number of stacked leaf springs.

However, for example, large trucks usually use 3 to 4 leaf springs, and further reducing this number not only creates a sense of uneasiness in appearance, but also creates friction between the leaf springs. There is a risk that the steering stability will deteriorate due to a decrease in the number of leaf springs, so reducing the weight by reducing the number of leaf springs is an afterthought.

In addition, for example, in a small truck having one or two leaf springs, it is difficult to further reduce the number of leaf springs even if there is sufficient stress.

On the other hand, if the stress is set high, it is possible to reduce the weight by narrowing the plate width, but if the plate width is narrowed over the entire length of the leaf spring, it becomes necessary to change the structure at the connection with the vehicle. This increases the number of types of related parts, which requires a lot of effort to manage, and also causes problems such as complicated connection work.

The present invention has been made under the above circumstances, and its purpose is to reduce the weight of a vehicle suspension plate without changing the number of leaf springs or the connection structure with the vehicle. The purpose is to provide a spring.

Hereinafter, the present invention will be described with reference to an illustrated embodiment.

In FIG. 1, a leaf spring device 1 includes a single leaf spring or a plurality of leaf springs 2 (in the case of three leaf springs in the figure) stacked in the thickness direction.

The leaf spring 2 has a longitudinal center part 3, plate end parts 4, 4, and tapered parts 5, 5 located between these parts 3 and 4, 4 and whose thickness decreases in the direction of the plate ends, For example, it is made in one piece from spring steel.

The central portion 3... is connected to the axle 7 of the vehicle via a U-bolt 6.6.

The first leaf spring 2 has eye portions 8, 8 integrally formed on both end portions 4, 4.

One of these eyepiece parts 8, 8 is connected to a vehicle body 11 through a bracket 9, and the other through a shackle 10.

The above general configuration may be the same as that of the conventional device.

In the plate spring 2, as illustrated in FIGS. 2A and 2B, the plate width b1 of the tapered portion 5 is equal to the width of each of the central portion 3 and the plate end portions 4.

and b2, and is formed to be substantially constant over the entire length.

In the figure, the thickness of the central portion 3 is t.

On the other hand, the thickness h of the plate end 4 and the thickness tx at a distance X from the load point are determined as follows, for example: ing.

Further, the plate width bx in the region where the distance X from the load point is 1, <x<t2 and L3<x<L4 is, for example, bx-b2+(b,-b2Xx4+)/(t2-,ff
+) bX-, g, +(b2- b+ Xx-mu)/(
23).

Now, as shown in Fig. 3, the thickness of the fixed proximal end is t.
, the length from the base end to the free end is L, the width is b, and the thickness tx at a distance X from the free end is 1x-t (x/
L) Considering the taper spring given by 3A, if the longitudinal elastic modulus is E, then the concentrated load P in the thickness direction on the free end
The deflection δ at the free end and the stress σ at the proximal end when
・・・・・・(1) σ-6PL/bt
It is expressed as (2).

In addition, the weight W is W-rbt beauty L (X/L
Ashi dx=(2/3)γbtu, (3).

Therefore, I=b are bl and b2 (where b+<b2), respectively, and the thickness t of the proximal end is t and 1, respectively.
．． (however, t + > t 2 ), the spring constant (P/δ
) are the same, if we add the suffixes 1 and 2 to the above symbols, then using equation (1) and setting δ to δ2, we get bl t+3""b2 t23
...(4) is obtained.

Also, from equations (2) and (3), σ, /σ2””” b
2 t 22/ b+ t+ 2W, /W22b+ri1
Since /b2t2 is obtained, it is known that σ, /σ22t + /l 2 > 1 Wl/W2=t 22/112<1 using equation (4).

That is, the width is < b2 and the thickness of the proximal end is t + > t
It is known that in the two types of taper springs No. 2, the stress at the base end is σ, >σ2, but the weight is W, <W2.

Figure 4 shows the weight ratio (W, /b2) to the plate width ratio (b, /b2).
'W2), stress ratio (σ, /σ2), thickness ratio (t+/12
).

In addition, Example A in which the dimensions of each part in FIGS.
.

Comparative Example C is thinner than Example A, and Example A has a constant plate width.
Thickness t at the center.

The performance compared to the comparative example, which is thicker and has a smaller number of polymerized sheets n, is compared to the second example.
A comparison is shown in the table.

As is clear from the table, Example A has the same spring constant as Comparative Examples C and D, the stress σ at the center against a load of 1100 kg is approximately 14 times smaller than that of the Comparative Example, and the weight W is lower than that of the Comparative Example. Approximately 16% lighter than Example C.

The stress σ distribution in the longitudinal direction (X direction) is the second
This is illustrated in Figure C.

Furthermore, compared to the main spring M whose dimensions of each part (see Fig. 2) are determined as shown in Table 3, the helper spring H8 has a narrower plate width at the tapered part and the plate end. Embodiment B with the addition of , and Comparative example E with the addition of a helper spring H2 with a constant plate width over the entire length.
The characteristics are shown in Table 4.

That is, by narrowing the plate width of the tapered portion of only the helper spring, the total weight can be reduced by about 4% (about 14% for only the helper spring).

It should be noted that the present invention is not limited to the above-mentioned embodiments. For example, the number of leaf springs constituting the leaf spring device can be appropriately set as necessary, and the present invention can also be applied to parent-child leaf spring devices. In addition, various modifications and applications are possible within the scope of the gist of the present invention.

In the present invention, as described above, the width of the tapered portion is made narrower than the width of each of the central portion and the edge portion of the plate.
The weight can be reduced without reducing the number of leaf springs compared to those with a constant leaf width.

In addition, the weight can be reduced while keeping the width of the center and edge parts constant, making it possible to standardize parts for connection to the vehicle wheels and body, making parts manufacturing and management simple and easy. becomes.

Furthermore, since the plate width can be set wide in the center, stress is low, and even if the tightening force of U-bolts, etc. is loosened, stress can be prevented from increasing at the periphery of the center bolt hole, and flexing can be prevented. This has the effect of suppressing the occurrence of breakage accidents caused by

[Brief explanation of drawings]

Figure 1 is a side view showing one embodiment of the present invention, Figures 2A and B
and C are side views, bottom views, and stress distribution diagrams of the leaf spring portion in the same example, Figures 3A and B are explanatory diagrams illustrating the side and top surfaces of the tapered spring, and Figure 4 is the plate width ratio in the same example. FIG. 3 is a diagram showing the relationship between weight ratio, stress ratio, and thickness ratio. 1... Leaf spring device, 2... Leaf spring, 3
...Central part, 4...Plate end, 5...
...Tapered part, 7...Axle, 11...
...Car body.

Claims (1)

[Claims] 1. Integrally includes a center portion and plate end portions connected to the vehicle wheel side and vehicle body side, respectively, and a tapered portion located between the center portion and plate end portions and decreasing in thickness in the direction of the plate end. A leaf spring for suspending a vehicle, characterized in that the width of the tapered portion is narrower than the widths of the central portion and the end portions of the plate.