JPS5837332A - Leaf spring for vehicle suspension - Google Patents

Abstract

PURPOSE:To lighten the weight of components without reduction in a number of laminated leaf springs or any modification of connecting mechanisms to a vehicle chassis or wheels by a method wherein width of the tapered pant of the leaf spring whose thickness is reduced toward the end of the leaf spring is designed to be narrower than widths of the center section and of the end section of the leaf spring. CONSTITUTION:A leaf spring 2 includes the center section of a entire length 3, end sections 4 and tapered pants 5 which are located between the center 3 and respective ends 4. Thickness of each tapered pant 5 is continously reduced toward the end section. The eaf spring is of a solid plate of spring steel and, for example, the width b1 of the tapered pant 5 is designed to be narrower than the width b0 of the center section 3 and the width b2 of the end section 4 and to be of approximately constant width over the whole length. Therefore, this permits light-weight construction withoug reduction in a number of leaf springs as compared with those laminated leaf springs consisting of an identical width of leaves. In addition, there is no need for requirement for modification of connecting mechanisms to wheels or vehicle chassis.

Description

[Detailed description of the invention] The present invention relates to a vehicle suspension leaf.

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. It is known that there are 4 parts. 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, in large trucks, etc., normally three to four leaf springs are used, and further reducing this number not only creates a sense of uneasiness in appearance, but also creates friction between the leaf springs. It is common knowledge that steering stability deteriorates 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, rig, etc. that has one or two plate ribs, it is difficult to further reduce the number of plates 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. tI
In Fig. c1, the 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) superimposed 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 an axle 7 of the vehicle via Uyf bolts 6', 6. The first leaf spring 2 is integrally formed at both end portions 4.4 and is provided with nine-eye portions 8,8. One of these eyepiece parts 8, 8 is connected to the vehicle body 11 through a bracket 9, and the other is connected to a vehicle body 11 through a shaft and a wheel 10, respectively. The above general configuration may be the same as that of the conventional device.

As illustrated in FIGS. 2(A) and 2(B), the leaf spring 2 has a plate width bl of the Teno base portion 5 which is narrower than each plate width bl of the center portion 3 and the plate end portions 4, and It is formed to be approximately constant over the entire length. In the same figure, the thickness tl of the plate end portion 4 with respect to the thickness to of the central portion 3 and the thickness tx at a position of distance X from the load point are, for example, t
1=to(ts/l)1'' tx=to(x/l) The plate width bX in the region is, for example, bx=bz+(bl −bsXx−tl)/(tm
tl)bz=ts+(bs-bxXx-ts)
/(ta-ts).

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 51 widths, and the thickness tx at the distance X from the free end is tx=t If the coefficient is E, then the deflection δ at the free end and the stress σ at the base end when the collector load P in the thickness direction acts on the free end are as follows: δ=8PL'/Ebi3... ...(
1) σ=6PL/bt (2
). Also, the weight W is W=γ where the specific gravity is γ.
bt/”(x/L)”dx=(2/3)rbtL”・
= (3). However, each width is bl.
and bx (where bl<bx), the thickness t of the proximal end is tl and tz (however, 11>1), and the spring constant (P/δ) is the same. If expressed with suffixes 1 and 2, using equation (1) and setting δl=δ2, bl tt =
bx tt song...(4) is obtained. Also, from equations (2) and (3), σt /6* = b s t
s2/bs t12W1/W goose=bt tt /b*
Since h is obtained, it is known that using equation (4), σ1/σ鵞−tt/ls>1 Wl/W鵞=t7/112(1. In other words, the width is bl<bl and the proximal end In the two types of Teno arm springs where the thickness of the part is ta>ts, the stress at the base end is σ1>σ3, but the weight is W
, is known to be <w weight.

Figure 4 shows the weight ratio (W
*/W), stress ratio (σ凰/σ3), and -s ratio (excluding t1/).

In addition, a comparison is made between the example plate in which the dimensions of each part in Fig. 2 (4) and (B) are determined as shown in Table 1, and the plate width is constant and the thickness t at the center part is thinner than that of the example plate. Table 2 shows the performance of Example C in comparison with Comparative Example C, which has a constant plate width, has a thicker thickness at the center than Example M, and has a smaller number of overlapping sheets n. 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 for a load of 1100 and # is approximately 14% smaller than that of the comparative example, and the weight W is about 16 inches lighter than Comparative Example C. The stress distribution in the longitudinal direction (X direction) is illustrated in FIG.

Furthermore, for the main spring M whose dimensions of each part (see Fig. 2) are determined as shown in Table 3, the plate widths b1 and b of the taper 4 part and the plate end! Table 4 shows the characteristics of Example B in which a helper spring jH1 having a narrow width was added, and Comparative Example E in which a helper spring H2 having a constant plate width over the entire length was added. In other words, by narrowing the plate width of the cheek part for only the Hertz 4 spring, the total weight can be reduced to about 4 inches (for the Hertz 4 spring only, the total weight is about 1 inch).
4%) can be made lighter.

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

Table 2 Table 3 Table 4 In the present invention, as described above, the plate width of the tapered portion is formed to be narrower than each of the plate widths of the center portion and the plate end portions.
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, even if the tightening force of the C1ty bolt, etc., which has low stress, loosens, the increase in stress at the periphery of the center bolt hole can be prevented. This has the effect of suppressing the occurrence of damage accidents caused by fretting.

[Brief explanation of drawings]

Figure 1 is a side view showing one embodiment of the present invention, Figure 2 (4)
, (B) and (Q are the side view, bottom view and stress distribution diagram of the leaf spring part in the same example, Fig. 3 (8) and (B)
is an explanatory diagram illustrating the side and top surfaces of the tapered spring;
The figure is a diagram showing the relationship between the plate width ratio, weight ratio, stress ratio, and thickness ratio in the same example. DESCRIPTION OF SYMBOLS 1..." Leaf spring device, 2... Leaf spring, 3... Center part, 4... Plate end part, 5... Taper 4 part, 7... Axle, 11... Vehicle body .Applicant's representative Patent attorney Suzue Takehiko Procedural amendment Showa ¥56.1F3.30th Japan Patent Office Commissioner Shima 1) Haruki Tono1, Indication of case Patent application No. 1983-1362642, Title of invention Vehicle suspension Relationship with the supplementary IE case for leaf springs 3 Patent applicant (464) NHK Spring Co., Ltd. 4, agent 5, voluntary amendment

Claims (1)

[Claims] One that integrally has a central portion and plate end portions connected to the wheel side and body side of the vehicle, respectively, and a tapered portion located between the central portion and the plate end portions and whose thickness decreases in the direction of the plate end. A leaf spring for suspending a vehicle, characterized in that the plate width of the fourth part is narrower than each of the plate widths of the central part and the plate end parts.